FreeBSD/Linux Kernel Cross Reference
sys/isa/sio.c

     /*-
      * Copyright (c) 1991 The Regents of the University of California.
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     *      from: @(#)com.c 7.5 (Berkeley) 5/16/91
     *      from: i386/isa sio.c,v 1.215
     */
    
    #include "opt_comconsole.h"
    #include "opt_compat.h"
    #include "opt_ddb.h"
    #include "opt_devfs.h"
    /* #include "opt_sio.h" */
    #include "sio.h"
    /* #include "pnp.h" */
    #define NPNP 0
    
    /*
     * Serial driver, based on 386BSD-0.1 com driver.
     * Mostly rewritten to use pseudo-DMA.
     * Works for National Semiconductor NS8250-NS16550AF UARTs.
     * COM driver, based on HP dca driver.
     *
     * Changes for PC-Card integration:
     *      - Added PC-Card driver table and handlers
     */
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/reboot.h>
    #include <sys/malloc.h>
    #include <sys/tty.h>
    #include <sys/proc.h>
    #include <sys/module.h>
    #include <sys/conf.h>
    #include <sys/dkstat.h>
    #include <sys/fcntl.h>
    #include <sys/interrupt.h>
    #include <sys/kernel.h>
    #include <sys/syslog.h>
    #include <sys/sysctl.h>
    #include <sys/bus.h>
    #include <sys/rman.h>
    #ifdef DEVFS
    #include <sys/devfsext.h>
    #endif
    
    #include <isa/isareg.h>
    #include <isa/isavar.h>
    #include <machine/lock.h>
    
    #include <machine/clock.h>
    #include <machine/ipl.h>
    #include <machine/resource.h>
    
    #include <isa/sioreg.h>
    
    #ifdef COM_ESP
    #include <isa/ic/esp.h>
    #endif
    #include <isa/ic/ns16550.h>
    
    #if 0
    
    #include "card.h"
    #if NCARD > 0
    #include <sys/module.h>
    #include <pccard/cardinfo.h>
    #include <pccard/slot.h>
    #endif
    
   #if NPNP > 0
   #include <i386/isa/pnp.h>
   #endif
   
   #endif
   
   #define disable_intr()  0
   #define enable_intr()   0
   
   #ifdef SMP
   #define disable_intr()  COM_DISABLE_INTR()
   #define enable_intr()   COM_ENABLE_INTR()
   #endif /* SMP */
   
   #ifndef EXTRA_SIO
   #if NPNP > 0
   #define EXTRA_SIO MAX_PNP_CARDS
   #else
   #define EXTRA_SIO 0
   #endif
   #endif
   
   #define NSIOTOT (NSIO + EXTRA_SIO)
   
   #define LOTS_OF_EVENTS  64      /* helps separate urgent events from input */
   #define RS_IBUFSIZE     256
   
   #define CALLOUT_MASK            0x80
   #define CONTROL_MASK            0x60
   #define CONTROL_INIT_STATE      0x20
   #define CONTROL_LOCK_STATE      0x40
   #define DEV_TO_UNIT(dev)        (MINOR_TO_UNIT(minor(dev)))
   #define MINOR_MAGIC_MASK        (CALLOUT_MASK | CONTROL_MASK)
   #define MINOR_TO_UNIT(mynor)    ((mynor) & ~MINOR_MAGIC_MASK)
   
   #ifdef COM_MULTIPORT
   /* checks in flags for multiport and which is multiport "master chip"
    * for a given card
    */
   #define COM_ISMULTIPORT(flags)  ((flags) & 0x01)
   #define COM_MPMASTER(flags)     (((flags) >> 8) & 0x0ff)
   #define COM_NOTAST4(flags)      ((flags) & 0x04)
   #endif /* COM_MULTIPORT */
   
   #define COM_CONSOLE(flags)      ((flags) & 0x10)
   #define COM_FORCECONSOLE(flags) ((flags) & 0x20)
   #define COM_LLCONSOLE(flags)    ((flags) & 0x40)
   #define COM_LOSESOUTINTS(flags) ((flags) & 0x08)
   #define COM_NOFIFO(flags)               ((flags) & 0x02)
   #define COM_ST16650A(flags)     ((flags) & 0x20000)
   #define COM_C_NOPROBE           (0x40000)
   #define COM_NOPROBE(flags)      ((flags) & COM_C_NOPROBE)
   #define COM_C_IIR_TXRDYBUG      (0x80000)
   #define COM_IIR_TXRDYBUG(flags) ((flags) & COM_C_IIR_TXRDYBUG)
   #define COM_FIFOSIZE(flags)     (((flags) & 0xff000000) >> 24)
   
   #define com_scr         7       /* scratch register for 16450-16550 (R/W) */
   
   /*
    * Input buffer watermarks.
    * The external device is asked to stop sending when the buffer exactly reaches
    * high water, or when the high level requests it.
    * The high level is notified immediately (rather than at a later clock tick)
    * when this watermark is reached.
    * The buffer size is chosen so the watermark should almost never be reached.
    * The low watermark is invisibly 0 since the buffer is always emptied all at
    * once.
    */
   #define RS_IHIGHWATER (3 * RS_IBUFSIZE / 4)
   
   /*
    * com state bits.
    * (CS_BUSY | CS_TTGO) and (CS_BUSY | CS_TTGO | CS_ODEVREADY) must be higher
    * than the other bits so that they can be tested as a group without masking
    * off the low bits.
    *
    * The following com and tty flags correspond closely:
    *      CS_BUSY         = TS_BUSY (maintained by comstart(), siopoll() and
    *                                 siostop())
    *      CS_TTGO         = ~TS_TTSTOP (maintained by comparam() and comstart())
    *      CS_CTS_OFLOW    = CCTS_OFLOW (maintained by comparam())
    *      CS_RTS_IFLOW    = CRTS_IFLOW (maintained by comparam())
    * TS_FLUSH is not used.
    * XXX I think TIOCSETA doesn't clear TS_TTSTOP when it clears IXON.
    * XXX CS_*FLOW should be CF_*FLOW in com->flags (control flags not state).
    */
   #define CS_BUSY         0x80    /* output in progress */
   #define CS_TTGO         0x40    /* output not stopped by XOFF */
   #define CS_ODEVREADY    0x20    /* external device h/w ready (CTS) */
   #define CS_CHECKMSR     1       /* check of MSR scheduled */
   #define CS_CTS_OFLOW    2       /* use CTS output flow control */
   #define CS_DTR_OFF      0x10    /* DTR held off */
   #define CS_ODONE        4       /* output completed */
   #define CS_RTS_IFLOW    8       /* use RTS input flow control */
   #define CSE_BUSYCHECK   1       /* siobusycheck() scheduled */
   
   static  char const * const      error_desc[] = {
   #define CE_OVERRUN                      0
           "silo overflow",
   #define CE_INTERRUPT_BUF_OVERFLOW       1
           "interrupt-level buffer overflow",
   #define CE_TTY_BUF_OVERFLOW             2
           "tty-level buffer overflow",
   };
   
   #define CE_NTYPES                       3
   #define CE_RECORD(com, errnum)          (++(com)->delta_error_counts[errnum])
   
   /* types.  XXX - should be elsewhere */
   typedef u_int   Port_t;         /* hardware port */
   typedef u_char  bool_t;         /* boolean */
   
   /* queue of linear buffers */
   struct lbq {
           u_char  *l_head;        /* next char to process */
           u_char  *l_tail;        /* one past the last char to process */
           struct lbq *l_next;     /* next in queue */
           bool_t  l_queued;       /* nonzero if queued */
   };
   
   /* com device structure */
   struct com_s {
           u_int   flags;          /* Copy isa device flags */
           u_char  state;          /* miscellaneous flag bits */
           bool_t  active_out;     /* nonzero if the callout device is open */
           u_char  cfcr_image;     /* copy of value written to CFCR */
   #ifdef COM_ESP
           bool_t  esp;            /* is this unit a hayes esp board? */
   #endif
           u_char  extra_state;    /* more flag bits, separate for order trick */
           u_char  fifo_image;     /* copy of value written to FIFO */
           bool_t  hasfifo;        /* nonzero for 16550 UARTs */
           bool_t  st16650a;       /* Is a Startech 16650A or RTS/CTS compat */
           bool_t  loses_outints;  /* nonzero if device loses output interrupts */
           u_char  mcr_image;      /* copy of value written to MCR */
   #ifdef COM_MULTIPORT
           bool_t  multiport;      /* is this unit part of a multiport device? */
   #endif /* COM_MULTIPORT */
           bool_t  no_irq;         /* nonzero if irq is not attached */
           bool_t  gone;           /* hardware disappeared */
           bool_t  poll;           /* nonzero if polling is required */
           bool_t  poll_output;    /* nonzero if polling for output is required */
           int     unit;           /* unit number */
           int     dtr_wait;       /* time to hold DTR down on close (* 1/hz) */
           u_int   tx_fifo_size;
           u_int   wopeners;       /* # processes waiting for DCD in open() */
   
           /*
            * The high level of the driver never reads status registers directly
            * because there would be too many side effects to handle conveniently.
            * Instead, it reads copies of the registers stored here by the
            * interrupt handler.
            */
           u_char  last_modem_status;      /* last MSR read by intr handler */
           u_char  prev_modem_status;      /* last MSR handled by high level */
   
           u_char  hotchar;        /* ldisc-specific char to be handled ASAP */
           u_char  *ibuf;          /* start of input buffer */
           u_char  *ibufend;       /* end of input buffer */
           u_char  *ihighwater;    /* threshold in input buffer */
           u_char  *iptr;          /* next free spot in input buffer */
   
           struct lbq      obufq;  /* head of queue of output buffers */
           struct lbq      obufs[2];       /* output buffers */
   
           Port_t  data_port;      /* i/o ports */
   #ifdef COM_ESP
           Port_t  esp_port;
   #endif
           Port_t  int_id_port;
           Port_t  iobase;
           Port_t  modem_ctl_port;
           Port_t  line_status_port;
           Port_t  modem_status_port;
           Port_t  intr_ctl_port;  /* Ports of IIR register */
   
           struct tty      *tp;    /* cross reference */
   
           /* Initial state. */
           struct termios  it_in;  /* should be in struct tty */
           struct termios  it_out;
   
           /* Lock state. */
           struct termios  lt_in;  /* should be in struct tty */
           struct termios  lt_out;
   
           bool_t  do_timestamp;
           bool_t  do_dcd_timestamp;
           struct timeval  timestamp;
           struct timeval  dcd_timestamp;
   
           u_long  bytes_in;       /* statistics */
           u_long  bytes_out;
           u_int   delta_error_counts[CE_NTYPES];
           u_long  error_counts[CE_NTYPES];
   
           /*
            * Ping-pong input buffers.  The extra factor of 2 in the sizes is
            * to allow for an error byte for each input byte.
            */
   #define CE_INPUT_OFFSET         RS_IBUFSIZE
           u_char  ibuf1[2 * RS_IBUFSIZE];
           u_char  ibuf2[2 * RS_IBUFSIZE];
   
           /*
            * Data area for output buffers.  Someday we should build the output
            * buffer queue without copying data.
            */
           u_char  obuf1[256];
           u_char  obuf2[256];
   #ifdef DEVFS
           void    *devfs_token_ttyd;
           void    *devfs_token_ttyl;
           void    *devfs_token_ttyi;
           void    *devfs_token_cuaa;
           void    *devfs_token_cual;
           void    *devfs_token_cuai;
   #endif
   };
   
   #ifdef COM_ESP
   static  int     espattach       __P((struct isa_device *isdp, struct com_s *com,
                                        Port_t esp_port));
   #endif
   static  int     sioattach       __P((device_t dev));
   
   static  timeout_t siobusycheck;
   static  timeout_t siodtrwakeup;
   static  void    comhardclose    __P((struct com_s *com));
   static  void    siointr1        __P((struct com_s *com));
   static  void    siointr         __P((void *arg));
   static  int     commctl         __P((struct com_s *com, int bits, int how));
   static  int     comparam        __P((struct tty *tp, struct termios *t));
   static  swihand_t siopoll;
   static  int     sioprobe        __P((device_t dev));
   static  void    siosettimeout   __P((void));
   static  void    comstart        __P((struct tty *tp));
   static  timeout_t comwakeup;
   static  void    disc_optim      __P((struct tty *tp, struct termios *t,
                                        struct com_s *com));
   
   #ifdef DSI_SOFT_MODEM
   static  int     LoadSoftModem   __P((int unit,int base_io, u_long size, u_char *ptr));
   #endif /* DSI_SOFT_MODEM */
   
   static char driver_name[] = "sio";
   
   /* table and macro for fast conversion from a unit number to its com struct */
   static  devclass_t      sio_devclass;
   #define com_addr(unit)  ((struct com_s *) \
                            devclass_get_softc(sio_devclass, unit))
   
   static device_method_t sio_methods[] = {
           /* Device interface */
           DEVMETHOD(device_probe,         sioprobe),
           DEVMETHOD(device_attach,        sioattach),
   
           { 0, 0 }
   };
   
   static driver_t sio_driver = {
           driver_name,
           sio_methods,
           DRIVER_TYPE_TTY,
           sizeof(struct com_s),
   };
   
   static  d_open_t        sioopen;
   static  d_close_t       sioclose;
   static  d_read_t        sioread;
   static  d_write_t       siowrite;
   static  d_ioctl_t       sioioctl;
   static  d_stop_t        siostop;
   static  d_devtotty_t    siodevtotty;
   
   #define CDEV_MAJOR      28
   static  struct cdevsw   sio_cdevsw = {
           sioopen,        sioclose,       sioread,        siowrite,
           sioioctl,       siostop,        noreset,        siodevtotty,
           ttpoll,         nommap,         NULL,           driver_name,
           NULL,           -1,             nodump,         nopsize,
           D_TTY,
   };
   
   int     comconsole = -1;
   static  volatile speed_t        comdefaultrate = CONSPEED;
   static  volatile speed_t        gdbdefaultrate = CONSPEED;
   static  u_int   com_events;     /* input chars + weighted output completions */
   static  Port_t  siocniobase;
   static  Port_t  siogdbiobase;
   static  bool_t  sio_registered;
   static  int     sio_timeout;
   static  int     sio_timeouts_until_log;
   static  struct  callout_handle sio_timeout_handle
       = CALLOUT_HANDLE_INITIALIZER(&sio_timeout_handle);
   #if 0 /* XXX */
   static struct tty       *sio_tty[NSIOTOT];
   #else
   static struct tty       sio_tty[NSIOTOT];
   #endif
   static  const int       nsio_tty = NSIOTOT;
   
   static  struct speedtab comspeedtab[] = {
           { 0,            0 },
           { 50,           COMBRD(50) },
           { 75,           COMBRD(75) },
           { 110,          COMBRD(110) },
           { 134,          COMBRD(134) },
           { 150,          COMBRD(150) },
           { 200,          COMBRD(200) },
           { 300,          COMBRD(300) },
           { 600,          COMBRD(600) },
           { 1200,         COMBRD(1200) },
           { 1800,         COMBRD(1800) },
           { 2400,         COMBRD(2400) },
           { 4800,         COMBRD(4800) },
           { 9600,         COMBRD(9600) },
           { 19200,        COMBRD(19200) },
           { 38400,        COMBRD(38400) },
           { 57600,        COMBRD(57600) },
           { 115200,       COMBRD(115200) },
           { -1,           -1 }
   };
   
   #ifdef COM_ESP
   /* XXX configure this properly. */
   static  Port_t  likely_com_ports[] = { 0x3f8, 0x2f8, 0x3e8, 0x2e8, };
   static  Port_t  likely_esp_ports[] = { 0x140, 0x180, 0x280, 0 };
   #endif
   
   /*
    * handle sysctl read/write requests for console speed
    * 
    * In addition to setting comdefaultrate for I/O through /dev/console,
    * also set the initial and lock values for the /dev/ttyXX device
    * if there is one associated with the console.  Finally, if the /dev/tty
    * device has already been open, change the speed on the open running port
    * itself.
    */
   
   static int
   sysctl_machdep_comdefaultrate SYSCTL_HANDLER_ARGS
   {
           int error, s;
           speed_t newspeed;
           struct com_s *com;
           struct tty *tp;
   
           newspeed = comdefaultrate;
   
           error = sysctl_handle_opaque(oidp, &newspeed, sizeof newspeed, req);
           if (error || !req->newptr)
                   return (error);
   
           comdefaultrate = newspeed;
   
           if (comconsole < 0)             /* serial console not selected? */
                   return (0);
   
           com = com_addr(comconsole);
           if (!com)
                   return (ENXIO);
   
           /*
            * set the initial and lock rates for /dev/ttydXX and /dev/cuaXX
            * (note, the lock rates really are boolean -- if non-zero, disallow
            *  speed changes)
            */
           com->it_in.c_ispeed  = com->it_in.c_ospeed =
           com->lt_in.c_ispeed  = com->lt_in.c_ospeed =
           com->it_out.c_ispeed = com->it_out.c_ospeed =
           com->lt_out.c_ispeed = com->lt_out.c_ospeed = comdefaultrate;
   
           /*
            * if we're open, change the running rate too
            */
           tp = com->tp;
           if (tp && (tp->t_state & TS_ISOPEN)) {
                   tp->t_termios.c_ispeed =
                   tp->t_termios.c_ospeed = comdefaultrate;
                   s = spltty();
                   error = comparam(tp, &tp->t_termios);
                   splx(s);
           }
           return error;
   }
   
   SYSCTL_PROC(_machdep, OID_AUTO, conspeed, CTLTYPE_INT | CTLFLAG_RW,
               0, 0, sysctl_machdep_comdefaultrate, "I", "");
   
   #if NCARD > 0
   /*
    *      PC-Card (PCMCIA) specific code.
    */
   static int      sioinit         __P((struct pccard_devinfo *));
   static void     siounload       __P((struct pccard_devinfo *));
   static int      card_intr       __P((struct pccard_devinfo *));
   
   PCCARD_MODULE(sio, sioinit, siounload, card_intr, 0, tty_imask);
   
   /*
    *      Initialize the device - called from Slot manager.
    */
   int
   sioinit(struct pccard_devinfo *devi)
   {
   
           /* validate unit number. */
           if (devi->isahd.id_unit >= (NSIOTOT))
                   return(ENODEV);
           /* Make sure it isn't already probed. */
           if (com_addr(devi->isahd.id_unit))
                   return(EBUSY);
   
           /* It's already probed as serial by Upper */
           devi->isahd.id_flags |= COM_C_NOPROBE; 
   
           /*
            * Probe the device. If a value is returned, the
            * device was found at the location.
            */
           if (sioprobe(&devi->isahd) == 0)
                   return(ENXIO);
           if (sioattach(&devi->isahd) == 0)
                   return(ENXIO);
   
           return(0);
   }
   
   /*
    *      siounload - unload the driver and clear the table.
    *      XXX TODO:
    *      This is usually called when the card is ejected, but
    *      can be caused by a modunload of a controller driver.
    *      The idea is to reset the driver's view of the device
    *      and ensure that any driver entry points such as
    *      read and write do not hang.
    */
   static void
   siounload(struct pccard_devinfo *devi)
   {
           struct com_s    *com;
   
           if (!devi) {
                   printf("NULL devi in siounload\n");
                   return;
           }
           com = com_addr(devi->isahd.id_unit);
           if (!com) {
                   printf("NULL com in siounload\n");
                   return;
           }
           if (!com->iobase) {
                   printf("sio%d already unloaded!\n",devi->isahd.id_unit);
                   return;
           }
           if (com->tp && (com->tp->t_state & TS_ISOPEN)) {
                   com->gone = 1;
                   printf("sio%d: unload\n", devi->isahd.id_unit);
                   com->tp->t_gen++;
                   ttyclose(com->tp);
                   ttwakeup(com->tp);
                   ttwwakeup(com->tp);
           } else {
                   com_addr(com->unit) = NULL;
                   bzero(com, sizeof *com);
                   free(com,M_TTYS);
                   printf("sio%d: unload,gone\n", devi->isahd.id_unit);
           }
   }
   
   /*
    *      card_intr - Shared interrupt called from
    *      front end of PC-Card handler.
    */
   static int
   card_intr(struct pccard_devinfo *devi)
   {
           struct com_s    *com;
   
           COM_LOCK();
           com = com_addr(devi->isahd.id_unit);
           if (com && !com->gone)
                   siointr1(com_addr(devi->isahd.id_unit));
           COM_UNLOCK();
           return(1);
   }
   #endif /* NCARD > 0 */
   
   #define SET_FLAG(dev, bit)      isa_set_flags(dev, isa_get_flags(dev) | (bit))
   #define CLR_FLAG(dev, bit)      isa_set_flags(dev, isa_get_flags(dev) & ~(bit))
   
   static int
   sioprobe(dev)
           device_t        dev;
   {
           static bool_t   already_init;
           bool_t          failures[10];
           int             fn;
           device_t        idev;
           Port_t          iobase;
           intrmask_t      irqmap[4];
           intrmask_t      irqs;
           u_char          mcr_image;
           int             result;
           device_t        xdev;
           u_int           flags = isa_get_flags(dev);
   
           if (!already_init) {
                   /*
                    * Turn off MCR_IENABLE for all likely serial ports.  An unused
                    * port with its MCR_IENABLE gate open will inhibit interrupts
                    * from any used port that shares the interrupt vector.
                    * XXX the gate enable is elsewhere for some multiports.
                    */
                   device_t *devs;
                   int count, i;
   
                   devclass_get_devices(sio_devclass, &devs, &count);
                   for (i = 0; i < count; i++) {
                           xdev = devs[i];
                           outb(isa_get_port(xdev) + com_mcr, 0);
                   }
                   free(devs, M_TEMP);
                   already_init = TRUE;
           }
   
           if (COM_LLCONSOLE(flags)) {
                   printf("sio%d: reserved for low-level i/o\n",
                          device_get_unit(dev));
                   return (ENXIO);
           }
   
           /*
            * If the device is on a multiport card and has an AST/4
            * compatible interrupt control register, initialize this
            * register and prepare to leave MCR_IENABLE clear in the mcr.
            * Otherwise, prepare to set MCR_IENABLE in the mcr.
            * Point idev to the device struct giving the correct id_irq.
            * This is the struct for the master device if there is one.
            */
           idev = dev;
           mcr_image = MCR_IENABLE;
   #ifdef COM_MULTIPORT
           if (COM_ISMULTIPORT(flags)) {
                   idev = devclass_get_device(sio_devclass, COM_MPMASTER(flags));
                   if (idev == NULL) {
                           printf("sio%d: master device %d not configured\n",
                                  device_get_unit(dev), COM_MPMASTER(flags));
                           isa_set_irq(dev, 0);
                           idev = dev;
                   }
                   if (!COM_NOTAST4(flags)) {
                           outb(isa_get_port(idev) + com_scr,
                                isa_get_irq(idev) >= 0 ? 0x80 : 0);
                           mcr_image = 0;
                   }
           }
   #endif /* COM_MULTIPORT */
           if (isa_get_irq(idev) < 0)
                   mcr_image = 0;
   
           bzero(failures, sizeof failures);
           iobase = isa_get_port(dev);
   
           /*
            * We don't want to get actual interrupts, just masked ones.
            * Interrupts from this line should already be masked in the ICU,
            * but mask them in the processor as well in case there are some
            * (misconfigured) shared interrupts.
            */
           disable_intr();
   /* EXTRA DELAY? */
   
           /*
            * Initialize the speed and the word size and wait long enough to
            * drain the maximum of 16 bytes of junk in device output queues.
            * The speed is undefined after a master reset and must be set
            * before relying on anything related to output.  There may be
            * junk after a (very fast) soft reboot and (apparently) after
            * master reset.
            * XXX what about the UART bug avoided by waiting in comparam()?
            * We don't want to to wait long enough to drain at 2 bps.
            */
           if (iobase == siocniobase)
                   DELAY((16 + 1) * 1000000 / (comdefaultrate / 10));
           else {
                   outb(iobase + com_cfcr, CFCR_DLAB | CFCR_8BITS);
                   outb(iobase + com_dlbl, COMBRD(SIO_TEST_SPEED) & 0xff);
                   outb(iobase + com_dlbh, (u_int) COMBRD(SIO_TEST_SPEED) >> 8);
                   outb(iobase + com_cfcr, CFCR_8BITS);
                   DELAY((16 + 1) * 1000000 / (SIO_TEST_SPEED / 10));
           }
   
           /*
            * Enable the interrupt gate and disable device interupts.  This
            * should leave the device driving the interrupt line low and
            * guarantee an edge trigger if an interrupt can be generated.
            */
   /* EXTRA DELAY? */
           outb(iobase + com_mcr, mcr_image);
           outb(iobase + com_ier, 0);
           DELAY(1000);            /* XXX */
           irqmap[0] = isa_irq_pending();
   
           /*
            * Attempt to set loopback mode so that we can send a null byte
            * without annoying any external device.
            */
   /* EXTRA DELAY? */
           outb(iobase + com_mcr, mcr_image | MCR_LOOPBACK);
   
           /*
            * Attempt to generate an output interrupt.  On 8250's, setting
            * IER_ETXRDY generates an interrupt independent of the current
            * setting and independent of whether the THR is empty.  On 16450's,
            * setting IER_ETXRDY generates an interrupt independent of the
            * current setting.  On 16550A's, setting IER_ETXRDY only
            * generates an interrupt when IER_ETXRDY is not already set.
            */
           outb(iobase + com_ier, IER_ETXRDY);
   
           /*
            * On some 16x50 incompatibles, setting IER_ETXRDY doesn't generate
            * an interrupt.  They'd better generate one for actually doing
            * output.  Loopback may be broken on the same incompatibles but
            * it's unlikely to do more than allow the null byte out.
            */
           outb(iobase + com_data, 0);
           DELAY((1 + 2) * 1000000 / (SIO_TEST_SPEED / 10));
   
           /*
            * Turn off loopback mode so that the interrupt gate works again
            * (MCR_IENABLE was hidden).  This should leave the device driving
            * an interrupt line high.  It doesn't matter if the interrupt
            * line oscillates while we are not looking at it, since interrupts
            * are disabled.
            */
   /* EXTRA DELAY? */
           outb(iobase + com_mcr, mcr_image);
   
       /*
            * It's a definitly Serial PCMCIA(16550A), but still be required
            * for IIR_TXRDY implementation ( Palido 321s, DC-1S... )
            */
           if ( COM_NOPROBE(flags) ) {
                   /* Reading IIR register twice */
                   for ( fn = 0; fn < 2; fn ++ ) {
                           DELAY(10000);
                           failures[6] = inb(iobase + com_iir);
                   }
                   /* Check IIR_TXRDY clear ? */
                   isa_set_portsize(dev, IO_COMSIZE);
                   result = 0;
                   if ( failures[6] & IIR_TXRDY ) {
                           /* Nop, Double check with clearing IER */
                           outb(iobase + com_ier, 0);
                           if ( inb(iobase + com_iir) & IIR_NOPEND ) {
                                   /* Ok. we're familia this gang */
                                   SET_FLAG(dev, COM_C_IIR_TXRDYBUG); /* Set IIR_TXRDYBUG */
                           } else {
                                   /* Unknow, Just omit this chip.. XXX*/
                                   result = ENXIO;
                           }
                   } else {
                           /* OK. this is well-known guys */
                           CLR_FLAG(dev, COM_C_IIR_TXRDYBUG); /*Clear IIR_TXRDYBUG*/
                   }
                   outb(iobase + com_cfcr, CFCR_8BITS);
                   enable_intr();
                   return (iobase == siocniobase ? 0 : result);
           }
   
           /*
            * Check that
            *      o the CFCR, IER and MCR in UART hold the values written to them
            *        (the values happen to be all distinct - this is good for
            *        avoiding false positive tests from bus echoes).
            *      o an output interrupt is generated and its vector is correct.
            *      o the interrupt goes away when the IIR in the UART is read.
            */
   /* EXTRA DELAY? */
           failures[0] = inb(iobase + com_cfcr) - CFCR_8BITS;
           failures[1] = inb(iobase + com_ier) - IER_ETXRDY;
           failures[2] = inb(iobase + com_mcr) - mcr_image;
           DELAY(10000);           /* Some internal modems need this time */
           irqmap[1] = isa_irq_pending();
           failures[4] = (inb(iobase + com_iir) & IIR_IMASK) - IIR_TXRDY;
           DELAY(1000);            /* XXX */
           irqmap[2] = isa_irq_pending();
           failures[6] = (inb(iobase + com_iir) & IIR_IMASK) - IIR_NOPEND;
   
           /*
            * Turn off all device interrupts and check that they go off properly.
            * Leave MCR_IENABLE alone.  For ports without a master port, it gates
            * the OUT2 output of the UART to
            * the ICU input.  Closing the gate would give a floating ICU input
            * (unless there is another device driving at) and spurious interrupts.
            * (On the system that this was first tested on, the input floats high
            * and gives a (masked) interrupt as soon as the gate is closed.)
            */
           outb(iobase + com_ier, 0);
           outb(iobase + com_cfcr, CFCR_8BITS);    /* dummy to avoid bus echo */
           failures[7] = inb(iobase + com_ier);
           DELAY(1000);            /* XXX */
           irqmap[3] = isa_irq_pending();
           failures[9] = (inb(iobase + com_iir) & IIR_IMASK) - IIR_NOPEND;
   
           enable_intr();
   
           irqs = irqmap[1] & ~irqmap[0];
           if (isa_get_irq(idev) >= 0 && ((1 << isa_get_irq(idev)) & irqs) == 0)
                   printf(
                   "sio%d: configured irq %d not in bitmap of probed irqs %#x\n",
                       device_get_unit(dev), isa_get_irq(idev), irqs);
           if (bootverbose)
                   printf("sio%d: irq maps: %#x %#x %#x %#x\n",
                       device_get_unit(dev),
                       irqmap[0], irqmap[1], irqmap[2], irqmap[3]);
   
           isa_set_portsize(dev, IO_COMSIZE);
           result = 0;
           for (fn = 0; fn < sizeof failures; ++fn)
                   if (failures[fn]) {
                           outb(iobase + com_mcr, 0);
                           result = ENXIO;
                           if (bootverbose) {
                                   printf("sio%d: probe failed test(s):",
                                       device_get_unit(dev));
                                   for (fn = 0; fn < sizeof failures; ++fn)
                                           if (failures[fn])
                                                   printf(" %d", fn);
                                   printf("\n");
                           }
                           break;
                   }
           return (iobase == siocniobase ? 0 : result);
   }
   
   #ifdef COM_ESP
   static int
   espattach(isdp, com, esp_port)
           struct isa_device       *isdp;
           struct com_s            *com;
           Port_t                  esp_port;
   {
           u_char  dips;
           u_char  val;
   
           /*
            * Check the ESP-specific I/O port to see if we're an ESP
            * card.  If not, return failure immediately.
            */
           if ((inb(esp_port) & 0xf3) == 0) {
                   printf(" port 0x%x is not an ESP board?\n", esp_port);
                   return (0);
           }
   
           /*
            * We've got something that claims to be a Hayes ESP card.
            * Let's hope so.
            */
   
           /* Get the dip-switch configuration */
           outb(esp_port + ESP_CMD1, ESP_GETDIPS);
           dips = inb(esp_port + ESP_STATUS1);
   
           /*
            * Bits 0,1 of dips say which COM port we are.
            */
           if (com->iobase == likely_com_ports[dips & 0x03])
                   printf(" : ESP");
           else {
                   printf(" esp_port has com %d\n", dips & 0x03);
                   return (0);
           }
   
           /*
            * Check for ESP version 2.0 or later:  bits 4,5,6 = 010.
            */
           outb(esp_port + ESP_CMD1, ESP_GETTEST);
           val = inb(esp_port + ESP_STATUS1);      /* clear reg 1 */
           val = inb(esp_port + ESP_STATUS2);
           if ((val & 0x70) < 0x20) {
                   printf("-old (%o)", val & 0x70);
                   return (0);
           }
   
           /*
            * Check for ability to emulate 16550:  bit 7 == 1
            */
           if ((dips & 0x80) == 0) {
                   printf(" slave");
                   return (0);
           }
   
           /*
            * Okay, we seem to be a Hayes ESP card.  Whee.
            */
           com->esp = TRUE;
           com->esp_port = esp_port;
           return (1);
   }
   #endif /* COM_ESP */
   
   static int
   sioattach(dev)
           device_t        dev;
   {
           struct com_s    *com;
   #ifdef COM_ESP
           Port_t          *espp;
   #endif
           Port_t          iobase;
           int             s;
           int             unit;
           void            *ih;
           struct resource *res;
           int             zero = 0;
           u_int           flags = isa_get_flags(dev);
   
   #if 0
           isdp->id_ri_flags |= RI_FAST;
   #endif
           iobase = isa_get_port(dev);
           unit = device_get_unit(dev);
           com = device_get_softc(dev);
   
           /*
            * sioprobe() has initialized the device registers as follows:
            *      o cfcr = CFCR_8BITS.
            *        It is most important that CFCR_DLAB is off, so that the
            *        data port is not hidden when we enable interrupts.
            *      o ier = 0.
            *        Interrupts are only enabled when the line is open.
            *      o mcr = MCR_IENABLE, or 0 if the port has AST/4 compatible
            *        interrupt control register or the config specifies no irq.
            *        Keeping MCR_DTR and MCR_RTS off might stop the external
            *        device from sending before we are ready.
            */
           bzero(com, sizeof *com);
           com->unit = unit;
           com->cfcr_image = CFCR_8BITS;
           com->dtr_wait = 3 * hz;
           com->loses_outints = COM_LOSESOUTINTS(flags) != 0;
           com->no_irq = isa_get_irq(dev) < 0;
           com->tx_fifo_size = 1;
           com->iptr = com->ibuf = com->ibuf1;
           com->ibufend = com->ibuf1 + RS_IBUFSIZE;
           com->ihighwater = com->ibuf1 + RS_IHIGHWATER;
           com->obufs[0].l_head = com->obuf1;
           com->obufs[1].l_head = com->obuf2;
   
           com->iobase = iobase;
           com->data_port = iobase + com_data;
           com->int_id_port = iobase + com_iir;
           com->modem_ctl_port = iobase + com_mcr;
           com->mcr_image = inb(com->modem_ctl_port);
           com->line_status_port = iobase + com_lsr;
           com->modem_status_port = iobase + com_msr;
           com->intr_ctl_port = iobase + com_ier;
   
           /*
            * We don't use all the flags from <sys/ttydefaults.h> since they
            * are only relevant for logins.  It's important to have echo off
            * initially so that the line doesn't start blathering before the
            * echo flag can be turned off.
            */
           com->it_in.c_iflag = 0;
           com->it_in.c_oflag = 0;
           com->it_in.c_cflag = TTYDEF_CFLAG;
           com->it_in.c_lflag = 0;
           if (unit == comconsole) {
                   com->it_in.c_iflag = TTYDEF_IFLAG;
                   com->it_in.c_oflag = TTYDEF_OFLAG;
                   com->it_in.c_cflag = TTYDEF_CFLAG | CLOCAL;
                   com->it_in.c_lflag = TTYDEF_LFLAG;
                   com->lt_out.c_cflag = com->lt_in.c_cflag = CLOCAL;
                   com->lt_out.c_ispeed = com->lt_out.c_ospeed =
                   com->lt_in.c_ispeed = com->lt_in.c_ospeed =
                   com->it_in.c_ispeed = com->it_in.c_ospeed = comdefaultrate;
           } else
                   com->it_in.c_ispeed = com->it_in.c_ospeed = TTYDEF_SPEED;
           termioschars(&com->it_in);
           com->it_out = com->it_in;
   
           /* attempt to determine UART type */
           printf("sio%d: type", unit);
   
   #ifdef DSI_SOFT_MODEM
           if((inb(iobase+7) ^ inb(iobase+7)) & 0x80) {
               printf(" Digicom Systems, Inc. SoftModem");
           goto determined_type;
           }
   #endif /* DSI_SOFT_MODEM */
   
   #ifdef COM_MULTIPORT
           if (!COM_ISMULTIPORT(flags) && !COM_IIR_TXRDYBUG(flags))
   #else
           if (!COM_IIR_TXRDYBUG(flags))
  #endif
          {
                  u_char  scr;
                  u_char  scr1;
                  u_char  scr2;
  
                  scr = inb(iobase + com_scr);
                  outb(iobase + com_scr, 0xa5);
                  scr1 = inb(iobase + com_scr);
                  outb(iobase + com_scr, 0x5a);
                  scr2 = inb(iobase + com_scr);
                  outb(iobase + com_scr, scr);
                  if (scr1 != 0xa5 || scr2 != 0x5a) {
                          printf(" 8250");
                          goto determined_type;
                  }
          }
          outb(iobase + com_fifo, FIFO_ENABLE | FIFO_RX_HIGH);
          DELAY(100);
          com->st16650a = 0;
          switch (inb(com->int_id_port) & IIR_FIFO_MASK) {
          case FIFO_RX_LOW:
                  printf(" 16450");
                  break;
          case FIFO_RX_MEDL:
                  printf(" 16450?");
                  break;
          case FIFO_RX_MEDH:
                  printf(" 16550?");
                  break;
          case FIFO_RX_HIGH:
                  if (COM_NOFIFO(flags)) {
                          printf(" 16550A fifo disabled");
                  } else {
                          com->hasfifo = TRUE;
                          if (COM_ST16650A(flags)) {
                                  com->st16650a = 1;
                                  com->tx_fifo_size = 32;
                                  printf(" ST16650A");
                          } else {
                                  com->tx_fifo_size = COM_FIFOSIZE(flags);
                                  printf(" 16550A");
                          }
                  }
  #ifdef COM_ESP
                  for (espp = likely_esp_ports; *espp != 0; espp++)
                          if (espattach(dev, com, *espp)) {
                                  com->tx_fifo_size = 1024;
                                  break;
                          }
  #endif
                  if (!com->st16650a) {
                          if (!com->tx_fifo_size)
                                  com->tx_fifo_size = 16;
                          else
                                  printf(" lookalike with %d bytes FIFO",
                                      com->tx_fifo_size);
                  }
  
                  break;
          }
          
  #ifdef COM_ESP
          if (com->esp) {
                  /*
                   * Set 16550 compatibility mode.
                   * We don't use the ESP_MODE_SCALE bit to increase the
                   * fifo trigger levels because we can't handle large
                   * bursts of input.
                   * XXX flow control should be set in comparam(), not here.
                   */
                  outb(com->esp_port + ESP_CMD1, ESP_SETMODE);
                  outb(com->esp_port + ESP_CMD2, ESP_MODE_RTS | ESP_MODE_FIFO);
  
                  /* Set RTS/CTS flow control. */
                  outb(com->esp_port + ESP_CMD1, ESP_SETFLOWTYPE);
                  outb(com->esp_port + ESP_CMD2, ESP_FLOW_RTS);
                  outb(com->esp_port + ESP_CMD2, ESP_FLOW_CTS);
  
                  /* Set flow-control levels. */
                  outb(com->esp_port + ESP_CMD1, ESP_SETRXFLOW);
                  outb(com->esp_port + ESP_CMD2, HIBYTE(768));
                  outb(com->esp_port + ESP_CMD2, LOBYTE(768));
                  outb(com->esp_port + ESP_CMD2, HIBYTE(512));
                  outb(com->esp_port + ESP_CMD2, LOBYTE(512));
          }
  #endif /* COM_ESP */
          outb(iobase + com_fifo, 0);
  determined_type: ;
  
  #ifdef COM_MULTIPORT
          if (COM_ISMULTIPORT(flags)) {
                  com->multiport = TRUE;
                  printf(" (multiport");
                  if (unit == COM_MPMASTER(flags))
                          printf(" master");
                  printf(")");
                  com->no_irq =
                          isa_get_irq(devclass_get_device
                                      (sio_devclass, COM_MPMASTER(flags))) < 0;
           }
  #endif /* COM_MULTIPORT */
          if (unit == comconsole)
                  printf(", console");
          if ( COM_IIR_TXRDYBUG(flags) )
                  printf(" with a bogus IIR_TXRDY register");
          printf("\n");
  
          if (!sio_registered) {
                  register_swi(SWI_TTY, siopoll);
                  sio_registered = TRUE;
          }
  #ifdef DEVFS
          com->devfs_token_ttyd = devfs_add_devswf(&sio_cdevsw,
                  unit, DV_CHR,
                  UID_ROOT, GID_WHEEL, 0600, "ttyd%r", unit);
          com->devfs_token_ttyi = devfs_add_devswf(&sio_cdevsw,
                  unit | CONTROL_INIT_STATE, DV_CHR,
                  UID_ROOT, GID_WHEEL, 0600, "ttyid%r", unit);
          com->devfs_token_ttyl = devfs_add_devswf(&sio_cdevsw,
                  unit | CONTROL_LOCK_STATE, DV_CHR,
                  UID_ROOT, GID_WHEEL, 0600, "ttyld%r", unit);
          com->devfs_token_cuaa = devfs_add_devswf(&sio_cdevsw,
                  unit | CALLOUT_MASK, DV_CHR,
                  UID_UUCP, GID_DIALER, 0660, "cuaa%r", unit);
          com->devfs_token_cuai = devfs_add_devswf(&sio_cdevsw,
                  unit | CALLOUT_MASK | CONTROL_INIT_STATE, DV_CHR,
                  UID_UUCP, GID_DIALER, 0660, "cuaia%r", unit);
          com->devfs_token_cual = devfs_add_devswf(&sio_cdevsw,
                  unit | CALLOUT_MASK | CONTROL_LOCK_STATE, DV_CHR,
                  UID_UUCP, GID_DIALER, 0660, "cuala%r", unit);
  #endif
          com->flags = isa_get_flags(dev); /* Heritate id_flags for later */
  
          res = bus_alloc_resource(dev, SYS_RES_IRQ, &zero, 0ul, ~0ul, 1,
                                   RF_SHAREABLE | RF_ACTIVE);
          BUS_SETUP_INTR(device_get_parent(dev), dev, res, siointr, com,
                         &ih);
  
          return (0);
  }
  
  static int
  sioopen(dev, flag, mode, p)
          dev_t           dev;
          int             flag;
          int             mode;
          struct proc     *p;
  {
          struct com_s    *com;
          int             error;
          Port_t          iobase;
          int             mynor;
          int             s;
          struct tty      *tp;
          int             unit;
  
          mynor = minor(dev);
          unit = MINOR_TO_UNIT(mynor);
          if ((u_int) unit >= NSIOTOT || (com = com_addr(unit)) == NULL)
                  return (ENXIO);
          if (com->gone)
                  return (ENXIO);
          if (mynor & CONTROL_MASK)
                  return (0);
  #if 0 /* XXX */
          tp = com->tp = sio_tty[unit] = ttymalloc(sio_tty[unit]);
  #else
          tp = com->tp = &sio_tty[unit];
  #endif
          s = spltty();
          /*
           * We jump to this label after all non-interrupted sleeps to pick
           * up any changes of the device state.
           */
  open_top:
          while (com->state & CS_DTR_OFF) {
                  error = tsleep(&com->dtr_wait, TTIPRI | PCATCH, "siodtr", 0);
                  if (com_addr(unit) == NULL)
                          return (ENXIO);
                  if (error != 0 || com->gone)
                          goto out;
          }
          if (tp->t_state & TS_ISOPEN) {
                  /*
                   * The device is open, so everything has been initialized.
                   * Handle conflicts.
                   */
                  if (mynor & CALLOUT_MASK) {
                          if (!com->active_out) {
                                  error = EBUSY;
                                  goto out;
                          }
                  } else {
                          if (com->active_out) {
                                  if (flag & O_NONBLOCK) {
                                          error = EBUSY;
                                          goto out;
                                  }
                                  error = tsleep(&com->active_out,
                                                 TTIPRI | PCATCH, "siobi", 0);
                                  if (com_addr(unit) == NULL)
                                          return (ENXIO);
                                  if (error != 0 || com->gone)
                                          goto out;
                                  goto open_top;
                          }
                  }
                  if (tp->t_state & TS_XCLUDE &&
                      suser(p->p_ucred, &p->p_acflag)) {
                          error = EBUSY;
                          goto out;
                  }
          } else {
                  /*
                   * The device isn't open, so there are no conflicts.
                   * Initialize it.  Initialization is done twice in many
                   * cases: to preempt sleeping callin opens if we are
                   * callout, and to complete a callin open after DCD rises.
                   */
                  tp->t_oproc = comstart;
                  tp->t_param = comparam;
                  tp->t_dev = dev;
                  tp->t_termios = mynor & CALLOUT_MASK
                                  ? com->it_out : com->it_in;
                  tp->t_ififosize = 2 * RS_IBUFSIZE;
                  tp->t_ispeedwat = (speed_t)-1;
                  tp->t_ospeedwat = (speed_t)-1;
                  (void)commctl(com, TIOCM_DTR | TIOCM_RTS, DMSET);
                  com->poll = com->no_irq;
                  com->poll_output = com->loses_outints;
                  ++com->wopeners;
                  error = comparam(tp, &tp->t_termios);
                  --com->wopeners;
                  if (error != 0)
                          goto out;
                  /*
                   * XXX we should goto open_top if comparam() slept.
                   */
                  iobase = com->iobase;
                  if (com->hasfifo) {
                          /*
                           * (Re)enable and drain fifos.
                           *
                           * Certain SMC chips cause problems if the fifos
                           * are enabled while input is ready.  Turn off the
                           * fifo if necessary to clear the input.  We test
                           * the input ready bit after enabling the fifos
                           * since we've already enabled them in comparam()
                           * and to handle races between enabling and fresh
                           * input.
                           */
                          while (TRUE) {
                                  outb(iobase + com_fifo,
                                       FIFO_RCV_RST | FIFO_XMT_RST
                                       | com->fifo_image);
                                  /*
                                   * XXX the delays are for superstitious
                                   * historical reasons.  It must be less than
                                   * the character time at the maximum
                                   * supported speed (87 usec at 115200 bps
                                   * 8N1).  Otherwise we might loop endlessly
                                   * if data is streaming in.  We used to use
                                   * delays of 100.  That usually worked
                                   * because DELAY(100) used to usually delay
                                   * for about 85 usec instead of 100.
                                   */
                                  DELAY(50);
                                  if (!(inb(com->line_status_port) & LSR_RXRDY))
                                          break;
                                  outb(iobase + com_fifo, 0);
                                  DELAY(50);
                                  (void) inb(com->data_port);
                          }
                  }
  
                  disable_intr();
                  (void) inb(com->line_status_port);
                  (void) inb(com->data_port);
                  com->prev_modem_status = com->last_modem_status
                      = inb(com->modem_status_port);
                  if (COM_IIR_TXRDYBUG(com->flags)) {
                          outb(com->intr_ctl_port, IER_ERXRDY | IER_ERLS
                                                  | IER_EMSC);
                  } else {
                          outb(com->intr_ctl_port, IER_ERXRDY | IER_ETXRDY
                                                  | IER_ERLS | IER_EMSC);
                  }
                  enable_intr();
                  /*
                   * Handle initial DCD.  Callout devices get a fake initial
                   * DCD (trapdoor DCD).  If we are callout, then any sleeping
                   * callin opens get woken up and resume sleeping on "siobi"
                   * instead of "siodcd".
                   */
                  /*
                   * XXX `mynor & CALLOUT_MASK' should be
                   * `tp->t_cflag & (SOFT_CARRIER | TRAPDOOR_CARRIER) where
                   * TRAPDOOR_CARRIER is the default initial state for callout
                   * devices and SOFT_CARRIER is like CLOCAL except it hides
                   * the true carrier.
                   */
                  if (com->prev_modem_status & MSR_DCD || mynor & CALLOUT_MASK)
                          (*linesw[tp->t_line].l_modem)(tp, 1);
          }
          /*
           * Wait for DCD if necessary.
           */
          if (!(tp->t_state & TS_CARR_ON) && !(mynor & CALLOUT_MASK)
              && !(tp->t_cflag & CLOCAL) && !(flag & O_NONBLOCK)) {
                  ++com->wopeners;
                  error = tsleep(TSA_CARR_ON(tp), TTIPRI | PCATCH, "siodcd", 0);
                  if (com_addr(unit) == NULL)
                          return (ENXIO);
                  --com->wopeners;
                  if (error != 0 || com->gone)
                          goto out;
                  goto open_top;
          }
          error = (*linesw[tp->t_line].l_open)(dev, tp);
          disc_optim(tp, &tp->t_termios, com);
          if (tp->t_state & TS_ISOPEN && mynor & CALLOUT_MASK)
                  com->active_out = TRUE;
          siosettimeout();
  out:
          splx(s);
          if (!(tp->t_state & TS_ISOPEN) && com->wopeners == 0)
                  comhardclose(com);
          return (error);
  }
  
  static int
  sioclose(dev, flag, mode, p)
          dev_t           dev;
          int             flag;
          int             mode;
          struct proc     *p;
  {
          struct com_s    *com;
          int             mynor;
          int             s;
          struct tty      *tp;
  
          mynor = minor(dev);
          if (mynor & CONTROL_MASK)
                  return (0);
          com = com_addr(MINOR_TO_UNIT(mynor));
          tp = com->tp;
          s = spltty();
          (*linesw[tp->t_line].l_close)(tp, flag);
          disc_optim(tp, &tp->t_termios, com);
          siostop(tp, FREAD | FWRITE);
          comhardclose(com);
          ttyclose(tp);
          siosettimeout();
          splx(s);
          if (com->gone) {
                  printf("sio%d: gone\n", com->unit);
                  s = spltty();
                  bzero(tp,sizeof *tp);
                  bzero(com,sizeof *com);
                  splx(s);
          }
          return (0);
  }
  
  static void
  comhardclose(com)
          struct com_s    *com;
  {
          Port_t          iobase;
          int             s;
          struct tty      *tp;
          int             unit;
  
          unit = com->unit;
          iobase = com->iobase;
          s = spltty();
          com->poll = FALSE;
          com->poll_output = FALSE;
          com->do_timestamp = FALSE;
          com->do_dcd_timestamp = FALSE;
          outb(iobase + com_cfcr, com->cfcr_image &= ~CFCR_SBREAK);
          {
                  outb(iobase + com_ier, 0);
                  tp = com->tp;
                  if (tp->t_cflag & HUPCL
                      /*
                       * XXX we will miss any carrier drop between here and the
                       * next open.  Perhaps we should watch DCD even when the
                       * port is closed; it is not sufficient to check it at
                       * the next open because it might go up and down while
                       * we're not watching.
                       */
                      || !com->active_out
                         && !(com->prev_modem_status & MSR_DCD)
                         && !(com->it_in.c_cflag & CLOCAL)
                      || !(tp->t_state & TS_ISOPEN)) {
                          (void)commctl(com, TIOCM_DTR, DMBIC);
                          if (com->dtr_wait != 0 && !(com->state & CS_DTR_OFF)) {
                                  timeout(siodtrwakeup, com, com->dtr_wait);
                                  com->state |= CS_DTR_OFF;
                          }
                  }
          }
          if (com->hasfifo) {
                  /*
                   * Disable fifos so that they are off after controlled
                   * reboots.  Some BIOSes fail to detect 16550s when the
                   * fifos are enabled.
                   */
                  outb(iobase + com_fifo, 0);
          }
          com->active_out = FALSE;
          wakeup(&com->active_out);
          wakeup(TSA_CARR_ON(tp));        /* restart any wopeners */
          splx(s);
  }
  
  static int
  sioread(dev, uio, flag)
          dev_t           dev;
          struct uio      *uio;
          int             flag;
  {
          int             mynor;
          int             unit;
          struct tty      *tp;
  
          mynor = minor(dev);
          if (mynor & CONTROL_MASK)
                  return (ENODEV);
          unit = MINOR_TO_UNIT(mynor);
          if (com_addr(unit)->gone)
                  return (ENODEV);
          tp = com_addr(unit)->tp;
          return ((*linesw[tp->t_line].l_read)(tp, uio, flag));
  }
  
  static int
  siowrite(dev, uio, flag)
          dev_t           dev;
          struct uio      *uio;
          int             flag;
  {
          int             mynor;
          struct tty      *tp;
          int             unit;
  
          mynor = minor(dev);
          if (mynor & CONTROL_MASK)
                  return (ENODEV);
  
          unit = MINOR_TO_UNIT(mynor);
          if (com_addr(unit)->gone)
                  return (ENODEV);
          tp = com_addr(unit)->tp;
          /*
           * (XXX) We disallow virtual consoles if the physical console is
           * a serial port.  This is in case there is a display attached that
           * is not the console.  In that situation we don't need/want the X
           * server taking over the console.
           */
          if (constty != NULL && unit == comconsole)
                  constty = NULL;
          return ((*linesw[tp->t_line].l_write)(tp, uio, flag));
  }
  
  static void
  siobusycheck(chan)
          void    *chan;
  {
          struct com_s    *com;
          int             s;
  
          com = (struct com_s *)chan;
  
          /*
           * Clear TS_BUSY if low-level output is complete.
           * spl locking is sufficient because siointr1() does not set CS_BUSY.
           * If siointr1() clears CS_BUSY after we look at it, then we'll get
           * called again.  Reading the line status port outside of siointr1()
           * is safe because CS_BUSY is clear so there are no output interrupts
           * to lose.
           */
          s = spltty();
          if (com->state & CS_BUSY)
                  com->extra_state &= ~CSE_BUSYCHECK;     /* False alarm. */
          else if ((inb(com->line_status_port) & (LSR_TSRE | LSR_TXRDY))
              == (LSR_TSRE | LSR_TXRDY)) {
                  com->tp->t_state &= ~TS_BUSY;
                  ttwwakeup(com->tp);
                  com->extra_state &= ~CSE_BUSYCHECK;
          } else
                  timeout(siobusycheck, com, hz / 100);
          splx(s);
  }
  
  static void
  siodtrwakeup(chan)
          void    *chan;
  {
          struct com_s    *com;
  
          com = (struct com_s *)chan;
          com->state &= ~CS_DTR_OFF;
          wakeup(&com->dtr_wait);
  }
  
  void
  siointr(arg)
          void            *arg;
  {
  #ifndef COM_MULTIPORT
          COM_LOCK();
          siointr1((struct com_s *) arg);
          COM_UNLOCK();
  #else /* COM_MULTIPORT */
          bool_t          possibly_more_intrs;
  
          /*
           * Loop until there is no activity on any port.  This is necessary
           * to get an interrupt edge more than to avoid another interrupt.
           * If the IRQ signal is just an OR of the IRQ signals from several
           * devices, then the edge from one may be lost because another is
           * on.
           */
          COM_LOCK();
          do {
                  possibly_more_intrs = FALSE;
                  for (unit = 0; unit < NSIOTOT; ++unit) {
                          com = com_addr(unit);
                          /*
                           * XXX COM_LOCK();
                           * would it work here, or be counter-productive?
                           */
                          if (com != NULL 
                              && !com->gone
                              && (inb(com->int_id_port) & IIR_IMASK)
                                 != IIR_NOPEND) {
                                  siointr1(com);
                                  possibly_more_intrs = TRUE;
                          }
                          /* XXX COM_UNLOCK(); */
                  }
          } while (possibly_more_intrs);
          COM_UNLOCK();
  #endif /* COM_MULTIPORT */
  }
  
  static void
  siointr1(com)
          struct com_s    *com;
  {
          u_char  line_status;
          u_char  modem_status;
          u_char  *ioptr;
          u_char  recv_data;
          u_char  int_ident;
          u_char  int_ctl;
          u_char  int_ctl_new;
  
          int_ctl = inb(com->intr_ctl_port);
          int_ctl_new = int_ctl;
  
          while (!com->gone) {
                  line_status = inb(com->line_status_port);
  
                  /* input event? (check first to help avoid overruns) */
                  while (line_status & LSR_RCV_MASK) {
                          /* break/unnattached error bits or real input? */
                          if (!(line_status & LSR_RXRDY))
                                  recv_data = 0;
                          else
                                  recv_data = inb(com->data_port);
                          if (line_status & (LSR_BI | LSR_FE | LSR_PE)) {
                                  /*
                                   * Don't store BI if IGNBRK or FE/PE if IGNPAR.
                                   * Otherwise, push the work to a higher level
                                   * (to handle PARMRK) if we're bypassing.
                                   * Otherwise, convert BI/FE and PE+INPCK to 0.
                                   *
                                   * This makes bypassing work right in the
                                   * usual "raw" case (IGNBRK set, and IGNPAR
                                   * and INPCK clear).
                                   *
                                   * Note: BI together with FE/PE means just BI.
                                   */
                                  if (line_status & LSR_BI) {
  #if defined(DDB) && defined(BREAK_TO_DEBUGGER)
                                          if (com->unit == comconsole) {
                                                  breakpoint();
                                                  goto cont;
                                          }
  #endif
                                          if (com->tp == NULL
                                              || com->tp->t_iflag & IGNBRK)
                                                  goto cont;
                                  } else {
                                          if (com->tp == NULL
                                              || com->tp->t_iflag & IGNPAR)
                                                  goto cont;
                                  }
                                  if (com->tp->t_state & TS_CAN_BYPASS_L_RINT
                                      && (line_status & (LSR_BI | LSR_FE)
                                          || com->tp->t_iflag & INPCK))
                                          recv_data = 0;
                          }
                          ++com->bytes_in;
                          if (com->hotchar != 0 && recv_data == com->hotchar)
                                  setsofttty();
                          ioptr = com->iptr;
                          if (ioptr >= com->ibufend)
                                  CE_RECORD(com, CE_INTERRUPT_BUF_OVERFLOW);
                          else {
                                  if (com->do_timestamp)
                                          microtime(&com->timestamp);
                                  ++com_events;
                                  schedsofttty();
  #if 0 /* for testing input latency vs efficiency */
  if (com->iptr - com->ibuf == 8)
          setsofttty();
  #endif
                                  ioptr[0] = recv_data;
                                  ioptr[CE_INPUT_OFFSET] = line_status;
                                  com->iptr = ++ioptr;
                                  if (ioptr == com->ihighwater
                                      && com->state & CS_RTS_IFLOW)
                                          outb(com->modem_ctl_port,
                                               com->mcr_image &= ~MCR_RTS);
                                  if (line_status & LSR_OE)
                                          CE_RECORD(com, CE_OVERRUN);
                          }
  cont:
                          /*
                           * "& 0x7F" is to avoid the gcc-1.40 generating a slow
                           * jump from the top of the loop to here
                           */
                          line_status = inb(com->line_status_port) & 0x7F;
                  }
  
                  /* modem status change? (always check before doing output) */
                  modem_status = inb(com->modem_status_port);
                  if (modem_status != com->last_modem_status) {
                          if (com->do_dcd_timestamp
                              && !(com->last_modem_status & MSR_DCD)
                              && modem_status & MSR_DCD)
                                  microtime(&com->dcd_timestamp);
  
                          /*
                           * Schedule high level to handle DCD changes.  Note
                           * that we don't use the delta bits anywhere.  Some
                           * UARTs mess them up, and it's easy to remember the
                           * previous bits and calculate the delta.
                           */
                          com->last_modem_status = modem_status;
                          if (!(com->state & CS_CHECKMSR)) {
                                  com_events += LOTS_OF_EVENTS;
                                  com->state |= CS_CHECKMSR;
                                  setsofttty();
                          }
  
                          /* handle CTS change immediately for crisp flow ctl */
                          if (com->state & CS_CTS_OFLOW) {
                                  if (modem_status & MSR_CTS)
                                          com->state |= CS_ODEVREADY;
                                  else
                                          com->state &= ~CS_ODEVREADY;
                          }
                  }
  
                  /* output queued and everything ready? */
                  if (line_status & LSR_TXRDY
                      && com->state >= (CS_BUSY | CS_TTGO | CS_ODEVREADY)) {
                          ioptr = com->obufq.l_head;
                          if (com->tx_fifo_size > 1) {
                                  u_int   ocount;
  
                                  ocount = com->obufq.l_tail - ioptr;
                                  if (ocount > com->tx_fifo_size)
                                          ocount = com->tx_fifo_size;
                                  com->bytes_out += ocount;
                                  do
                                          outb(com->data_port, *ioptr++);
                                  while (--ocount != 0);
                          } else {
                                  outb(com->data_port, *ioptr++);
                                  ++com->bytes_out;
                          }
                          com->obufq.l_head = ioptr;
                          if (COM_IIR_TXRDYBUG(com->flags)) {
                                  int_ctl_new = int_ctl | IER_ETXRDY;
                          }
                          if (ioptr >= com->obufq.l_tail) {
                                  struct lbq      *qp;
  
                                  qp = com->obufq.l_next;
                                  qp->l_queued = FALSE;
                                  qp = qp->l_next;
                                  if (qp != NULL) {
                                          com->obufq.l_head = qp->l_head;
                                          com->obufq.l_tail = qp->l_tail;
                                          com->obufq.l_next = qp;
                                  } else {
                                          /* output just completed */
                                          if ( COM_IIR_TXRDYBUG(com->flags) ) {
                                                  int_ctl_new = int_ctl & ~IER_ETXRDY;
                                          }
                                          com->state &= ~CS_BUSY;
                                  }
                                  if (!(com->state & CS_ODONE)) {
                                          com_events += LOTS_OF_EVENTS;
                                          com->state |= CS_ODONE;
                                          setsofttty();   /* handle at high level ASAP */
                                  }
                          }
                          if ( COM_IIR_TXRDYBUG(com->flags) && (int_ctl != int_ctl_new)) {
                                  outb(com->intr_ctl_port, int_ctl_new);
                          }
                  }
  
                  /* finished? */
  #ifndef COM_MULTIPORT
                  if ((inb(com->int_id_port) & IIR_IMASK) == IIR_NOPEND)
  #endif /* COM_MULTIPORT */
                          return;
          }
  }
  
  static int
  sioioctl(dev, cmd, data, flag, p)
          dev_t           dev;
          u_long          cmd;
          caddr_t         data;
          int             flag;
          struct proc     *p;
  {
          struct com_s    *com;
          int             error;
          Port_t          iobase;
          int             mynor;
          int             s;
          struct tty      *tp;
  #if defined(COMPAT_43) || defined(COMPAT_SUNOS)
          u_long          oldcmd;
          struct termios  term;
  #endif
  
          mynor = minor(dev);
          com = com_addr(MINOR_TO_UNIT(mynor));
          if (com->gone)
                  return (ENODEV);
          iobase = com->iobase;
          if (mynor & CONTROL_MASK) {
                  struct termios  *ct;
  
                  switch (mynor & CONTROL_MASK) {
                  case CONTROL_INIT_STATE:
                          ct = mynor & CALLOUT_MASK ? &com->it_out : &com->it_in;
                          break;
                  case CONTROL_LOCK_STATE:
                          ct = mynor & CALLOUT_MASK ? &com->lt_out : &com->lt_in;
                          break;
                  default:
                          return (ENODEV);        /* /dev/nodev */
                  }
                  switch (cmd) {
                  case TIOCSETA:
                          error = suser(p->p_ucred, &p->p_acflag);
                          if (error != 0)
                                  return (error);
                          *ct = *(struct termios *)data;
                          return (0);
                  case TIOCGETA:
                          *(struct termios *)data = *ct;
                          return (0);
                  case TIOCGETD:
                          *(int *)data = TTYDISC;
                          return (0);
                  case TIOCGWINSZ:
                          bzero(data, sizeof(struct winsize));
                          return (0);
  #ifdef DSI_SOFT_MODEM
                  /*
                   * Download micro-code to Digicom modem.
                   */
                  case TIOCDSIMICROCODE:
                          {
                          u_long l;
                          u_char *p,*pi;
  
                          pi = (u_char*)(*(caddr_t*)data);
                          error = copyin(pi,&l,sizeof l);
                          if(error)
                                  {return error;};
                          pi += sizeof l;
  
                          p = malloc(l,M_TEMP,M_NOWAIT);
                          if(!p)
                                  {return ENOBUFS;}
                          error = copyin(pi,p,l);
                          if(error)
                                  {free(p,M_TEMP); return error;};
                          if(error = LoadSoftModem(
                              MINOR_TO_UNIT(mynor),iobase,l,p))
                                  {free(p,M_TEMP); return error;}
                          free(p,M_TEMP);
                          return(0);
                          }
  #endif /* DSI_SOFT_MODEM */
                  default:
                          return (ENOTTY);
                  }
          }
          tp = com->tp;
  #if defined(COMPAT_43) || defined(COMPAT_SUNOS)
          term = tp->t_termios;
          oldcmd = cmd;
          error = ttsetcompat(tp, &cmd, data, &term);
          if (error != 0)
                  return (error);
          if (cmd != oldcmd)
                  data = (caddr_t)&term;
  #endif
          if (cmd == TIOCSETA || cmd == TIOCSETAW || cmd == TIOCSETAF) {
                  int     cc;
                  struct termios *dt = (struct termios *)data;
                  struct termios *lt = mynor & CALLOUT_MASK
                                       ? &com->lt_out : &com->lt_in;
  
                  dt->c_iflag = (tp->t_iflag & lt->c_iflag)
                                | (dt->c_iflag & ~lt->c_iflag);
                  dt->c_oflag = (tp->t_oflag & lt->c_oflag)
                                | (dt->c_oflag & ~lt->c_oflag);
                  dt->c_cflag = (tp->t_cflag & lt->c_cflag)
                                | (dt->c_cflag & ~lt->c_cflag);
                  dt->c_lflag = (tp->t_lflag & lt->c_lflag)
                                | (dt->c_lflag & ~lt->c_lflag);
                  for (cc = 0; cc < NCCS; ++cc)
                          if (lt->c_cc[cc] != 0)
                                  dt->c_cc[cc] = tp->t_cc[cc];
                  if (lt->c_ispeed != 0)
                          dt->c_ispeed = tp->t_ispeed;
                  if (lt->c_ospeed != 0)
                          dt->c_ospeed = tp->t_ospeed;
          }
          error = (*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag, p);
          if (error != ENOIOCTL)
                  return (error);
          s = spltty();
          error = ttioctl(tp, cmd, data, flag);
          disc_optim(tp, &tp->t_termios, com);
          if (error != ENOIOCTL) {
                  splx(s);
                  return (error);
          }
          switch (cmd) {
          case TIOCSBRK:
                  outb(iobase + com_cfcr, com->cfcr_image |= CFCR_SBREAK);
                  break;
          case TIOCCBRK:
                  outb(iobase + com_cfcr, com->cfcr_image &= ~CFCR_SBREAK);
                  break;
          case TIOCSDTR:
                  (void)commctl(com, TIOCM_DTR, DMBIS);
                  break;
          case TIOCCDTR:
                  (void)commctl(com, TIOCM_DTR, DMBIC);
                  break;
          /*
           * XXX should disallow changing MCR_RTS if CS_RTS_IFLOW is set.  The
           * changes get undone on the next call to comparam().
           */
          case TIOCMSET:
                  (void)commctl(com, *(int *)data, DMSET);
                  break;
          case TIOCMBIS:
                  (void)commctl(com, *(int *)data, DMBIS);
                  break;
          case TIOCMBIC:
                  (void)commctl(com, *(int *)data, DMBIC);
                  break;
          case TIOCMGET:
                  *(int *)data = commctl(com, 0, DMGET);
                  break;
          case TIOCMSDTRWAIT:
                  /* must be root since the wait applies to following logins */
                  error = suser(p->p_ucred, &p->p_acflag);
                  if (error != 0) {
                          splx(s);
                          return (error);
                  }
                  com->dtr_wait = *(int *)data * hz / 100;
                  break;
          case TIOCMGDTRWAIT:
                  *(int *)data = com->dtr_wait * 100 / hz;
                  break;
          case TIOCTIMESTAMP:
                  com->do_timestamp = TRUE;
                  *(struct timeval *)data = com->timestamp;
                  break;
          case TIOCDCDTIMESTAMP:
                  com->do_dcd_timestamp = TRUE;
                  *(struct timeval *)data = com->dcd_timestamp;
                  break;
          default:
                  splx(s);
                  return (ENOTTY);
          }
          splx(s);
          return (0);
  }
  
  static void
  siopoll()
  {
          int             unit;
  
          if (com_events == 0)
                  return;
  repeat:
          for (unit = 0; unit < NSIOTOT; ++unit) {
                  u_char          *buf;
                  struct com_s    *com;
                  u_char          *ibuf;
                  int             incc;
                  struct tty      *tp;
  
                  com = com_addr(unit);
                  if (com == NULL)
                          continue;
                  tp = com->tp;
                  if (tp == NULL || com->gone) {
                          /*
                           * Discard any events related to never-opened or
                           * going-away devices.
                           */
                          disable_intr();
                          incc = com->iptr - com->ibuf;
                          com->iptr = com->ibuf;
                          if (com->state & CS_CHECKMSR) {
                                  incc += LOTS_OF_EVENTS;
                                  com->state &= ~CS_CHECKMSR;
                          }
                          com_events -= incc;
                          enable_intr();
                          continue;
                  }
  
                  /* switch the role of the low-level input buffers */
                  if (com->iptr == (ibuf = com->ibuf)) {
                          buf = NULL;     /* not used, but compiler can't tell */
                          incc = 0;
                  } else {
                          buf = ibuf;
                          disable_intr();
                          incc = com->iptr - buf;
                          com_events -= incc;
                          if (ibuf == com->ibuf1)
                                  ibuf = com->ibuf2;
                          else
                                  ibuf = com->ibuf1;
                          com->ibufend = ibuf + RS_IBUFSIZE;
                          com->ihighwater = ibuf + RS_IHIGHWATER;
                          com->iptr = ibuf;
  
                          /*
                           * There is now room for another low-level buffer full
                           * of input, so enable RTS if it is now disabled and
                           * there is room in the high-level buffer.
                           */
                          if ((com->state & CS_RTS_IFLOW)
                              && !(com->mcr_image & MCR_RTS)
                              && !(tp->t_state & TS_TBLOCK))
                                  outb(com->modem_ctl_port,
                                       com->mcr_image |= MCR_RTS);
                          enable_intr();
                          com->ibuf = ibuf;
                  }
  
                  if (com->state & CS_CHECKMSR) {
                          u_char  delta_modem_status;
  
                          disable_intr();
                          delta_modem_status = com->last_modem_status
                                               ^ com->prev_modem_status;
                          com->prev_modem_status = com->last_modem_status;
                          com_events -= LOTS_OF_EVENTS;
                          com->state &= ~CS_CHECKMSR;
                          enable_intr();
                          if (delta_modem_status & MSR_DCD)
                                  (*linesw[tp->t_line].l_modem)
                                          (tp, com->prev_modem_status & MSR_DCD);
                  }
                  if (com->state & CS_ODONE) {
                          disable_intr();
                          com_events -= LOTS_OF_EVENTS;
                          com->state &= ~CS_ODONE;
                          enable_intr();
                          if (!(com->state & CS_BUSY)
                              && !(com->extra_state & CSE_BUSYCHECK)) {
                                  timeout(siobusycheck, com, hz / 100);
                                  com->extra_state |= CSE_BUSYCHECK;
                          }
                          (*linesw[tp->t_line].l_start)(tp);
                  }
                  if (incc <= 0 || !(tp->t_state & TS_ISOPEN) ||
                      !(tp->t_cflag & CREAD))
                          continue;
                  /*
                   * Avoid the grotesquely inefficient lineswitch routine
                   * (ttyinput) in "raw" mode.  It usually takes about 450
                   * instructions (that's without canonical processing or echo!).
                   * slinput is reasonably fast (usually 40 instructions plus
                   * call overhead).
                   */
                  if (tp->t_state & TS_CAN_BYPASS_L_RINT) {
                          if (tp->t_rawq.c_cc + incc > tp->t_ihiwat
                              && (com->state & CS_RTS_IFLOW
                                  || tp->t_iflag & IXOFF)
                              && !(tp->t_state & TS_TBLOCK))
                                  ttyblock(tp);
                          tk_nin += incc;
                          tk_rawcc += incc;
                          tp->t_rawcc += incc;
                          com->delta_error_counts[CE_TTY_BUF_OVERFLOW]
                                  += b_to_q((char *)buf, incc, &tp->t_rawq);
                          ttwakeup(tp);
                          if (tp->t_state & TS_TTSTOP
                              && (tp->t_iflag & IXANY
                                  || tp->t_cc[VSTART] == tp->t_cc[VSTOP])) {
                                  tp->t_state &= ~TS_TTSTOP;
                                  tp->t_lflag &= ~FLUSHO;
                                  comstart(tp);
                          }
                  } else {
                          do {
                                  u_char  line_status;
                                  int     recv_data;
  
                                  line_status = (u_char) buf[CE_INPUT_OFFSET];
                                  recv_data = (u_char) *buf++;
                                  if (line_status
                                      & (LSR_BI | LSR_FE | LSR_OE | LSR_PE)) {
                                          if (line_status & LSR_BI)
                                                  recv_data |= TTY_BI;
                                          if (line_status & LSR_FE)
                                                  recv_data |= TTY_FE;
                                          if (line_status & LSR_OE)
                                                  recv_data |= TTY_OE;
                                          if (line_status & LSR_PE)
                                                  recv_data |= TTY_PE;
                                  }
                                  (*linesw[tp->t_line].l_rint)(recv_data, tp);
                          } while (--incc > 0);
                  }
                  if (com_events == 0)
                          break;
          }
          if (com_events >= LOTS_OF_EVENTS)
                  goto repeat;
  }
  
  static int
  comparam(tp, t)
          struct tty      *tp;
          struct termios  *t;
  {
          u_int           cfcr;
          int             cflag;
          struct com_s    *com;
          int             divisor;
          u_char          dlbh;
          u_char          dlbl;
          int             error;
          Port_t          iobase;
          int             s;
          int             unit;
          int             txtimeout;
  
          /* do historical conversions */
          if (t->c_ispeed == 0)
                  t->c_ispeed = t->c_ospeed;
  
          /* check requested parameters */
          divisor = ttspeedtab(t->c_ospeed, comspeedtab);
          if (divisor < 0 || divisor > 0 && t->c_ispeed != t->c_ospeed)
                  return (EINVAL);
  
          /* parameters are OK, convert them to the com struct and the device */
          unit = DEV_TO_UNIT(tp->t_dev);
          com = com_addr(unit);
          iobase = com->iobase;
          s = spltty();
          if (divisor == 0)
                  (void)commctl(com, TIOCM_DTR, DMBIC);   /* hang up line */
          else
                  (void)commctl(com, TIOCM_DTR, DMBIS);
          cflag = t->c_cflag;
          switch (cflag & CSIZE) {
          case CS5:
                  cfcr = CFCR_5BITS;
                  break;
          case CS6:
                  cfcr = CFCR_6BITS;
                  break;
          case CS7:
                  cfcr = CFCR_7BITS;
                  break;
          default:
                  cfcr = CFCR_8BITS;
                  break;
          }
          if (cflag & PARENB) {
                  cfcr |= CFCR_PENAB;
                  if (!(cflag & PARODD))
                          cfcr |= CFCR_PEVEN;
          }
          if (cflag & CSTOPB)
                  cfcr |= CFCR_STOPB;
  
          if (com->hasfifo && divisor != 0) {
                  /*
                   * Use a fifo trigger level low enough so that the input
                   * latency from the fifo is less than about 16 msec and
                   * the total latency is less than about 30 msec.  These
                   * latencies are reasonable for humans.  Serial comms
                   * protocols shouldn't expect anything better since modem
                   * latencies are larger.
                   */
                  com->fifo_image = t->c_ospeed <= 4800
                                    ? FIFO_ENABLE : FIFO_ENABLE | FIFO_RX_HIGH;
  #ifdef COM_ESP
                  /*
                   * The Hayes ESP card needs the fifo DMA mode bit set
                   * in compatibility mode.  If not, it will interrupt
                   * for each character received.
                   */
                  if (com->esp)
                          com->fifo_image |= FIFO_DMA_MODE;
  #endif
                  outb(iobase + com_fifo, com->fifo_image);
          }
  
          /*
           * Some UARTs lock up if the divisor latch registers are selected
           * while the UART is doing output (they refuse to transmit anything
           * more until given a hard reset).  Fix this by stopping filling
           * the device buffers and waiting for them to drain.  Reading the
           * line status port outside of siointr1() might lose some receiver
           * error bits, but that is acceptable here.
           */
          disable_intr();
  retry:
          com->state &= ~CS_TTGO;
          txtimeout = tp->t_timeout;
          enable_intr();
          while ((inb(com->line_status_port) & (LSR_TSRE | LSR_TXRDY))
                 != (LSR_TSRE | LSR_TXRDY)) {
                  tp->t_state |= TS_SO_OCOMPLETE;
                  error = ttysleep(tp, TSA_OCOMPLETE(tp), TTIPRI | PCATCH,
                                   "siotx", hz / 100);
                  if (   txtimeout != 0
                      && (!error || error == EAGAIN)
                      && (txtimeout -= hz / 100) <= 0
                     )
                          error = EIO;
                  if (com->gone)
                          error = ENODEV;
                  if (error != 0 && error != EAGAIN) {
                          if (!(tp->t_state & TS_TTSTOP)) {
                                  disable_intr();
                                  com->state |= CS_TTGO;
                                  enable_intr();
                          }
                          splx(s);
                          return (error);
                  }
          }
  
          disable_intr();         /* very important while com_data is hidden */
  
          /*
           * XXX - clearing CS_TTGO is not sufficient to stop further output,
           * because siopoll() calls comstart() which usually sets it again
           * because TS_TTSTOP is clear.  Setting TS_TTSTOP would not be
           * sufficient, for similar reasons.
           */
          if ((inb(com->line_status_port) & (LSR_TSRE | LSR_TXRDY))
              != (LSR_TSRE | LSR_TXRDY))
                  goto retry;
  
          if (divisor != 0) {
                  outb(iobase + com_cfcr, cfcr | CFCR_DLAB);
                  /*
                   * Only set the divisor registers if they would change,
                   * since on some 16550 incompatibles (UMC8669F), setting
                   * them while input is arriving them loses sync until
                   * data stops arriving.
                   */
                  dlbl = divisor & 0xFF;
                  if (inb(iobase + com_dlbl) != dlbl)
                          outb(iobase + com_dlbl, dlbl);
                  dlbh = (u_int) divisor >> 8;
                  if (inb(iobase + com_dlbh) != dlbh)
                          outb(iobase + com_dlbh, dlbh);
          }
  
  
          outb(iobase + com_cfcr, com->cfcr_image = cfcr);
  
          if (!(tp->t_state & TS_TTSTOP))
                  com->state |= CS_TTGO;
  
          if (cflag & CRTS_IFLOW) {
                  if (com->st16650a) {
                          outb(iobase + com_cfcr, 0xbf);
                          outb(iobase + com_fifo, inb(iobase + com_fifo) | 0x40);
                  }
                  com->state |= CS_RTS_IFLOW;
                  /*
                   * If CS_RTS_IFLOW just changed from off to on, the change
                   * needs to be propagated to MCR_RTS.  This isn't urgent,
                   * so do it later by calling comstart() instead of repeating
                   * a lot of code from comstart() here.
                   */
          } else if (com->state & CS_RTS_IFLOW) {
                  com->state &= ~CS_RTS_IFLOW;
                  /*
                   * CS_RTS_IFLOW just changed from on to off.  Force MCR_RTS
                   * on here, since comstart() won't do it later.
                   */
                  outb(com->modem_ctl_port, com->mcr_image |= MCR_RTS);
                  if (com->st16650a) {
                          outb(iobase + com_cfcr, 0xbf);
                          outb(iobase + com_fifo, inb(iobase + com_fifo) & ~0x40);
                  }
          }
  
  
          /*
           * Set up state to handle output flow control.
           * XXX - worth handling MDMBUF (DCD) flow control at the lowest level?
           * Now has 10+ msec latency, while CTS flow has 50- usec latency.
           */
          com->state |= CS_ODEVREADY;
          com->state &= ~CS_CTS_OFLOW;
          if (cflag & CCTS_OFLOW) {
                  com->state |= CS_CTS_OFLOW;
                  if (!(com->last_modem_status & MSR_CTS))
                          com->state &= ~CS_ODEVREADY;
                  if (com->st16650a) {
                          outb(iobase + com_cfcr, 0xbf);
                          outb(iobase + com_fifo, inb(iobase + com_fifo) | 0x80);
                  }
          } else {
                  if (com->st16650a) {
                          outb(iobase + com_cfcr, 0xbf);
                          outb(iobase + com_fifo, inb(iobase + com_fifo) & ~0x80);
                  }
          }
  
  
          outb(iobase + com_cfcr, com->cfcr_image);
  
  
          /* XXX shouldn't call functions while intrs are disabled. */
          disc_optim(tp, t, com);
          /*
           * Recover from fiddling with CS_TTGO.  We used to call siointr1()
           * unconditionally, but that defeated the careful discarding of
           * stale input in sioopen().
           */
          if (com->state >= (CS_BUSY | CS_TTGO))
                  siointr1(com);
  
          enable_intr();
          splx(s);
          comstart(tp);
          return (0);
  }
  
  static void
  comstart(tp)
          struct tty      *tp;
  {
          struct com_s    *com;
          int             s;
          int             unit;
  
          unit = DEV_TO_UNIT(tp->t_dev);
          com = com_addr(unit);
          s = spltty();
          disable_intr();
          if (tp->t_state & TS_TTSTOP)
                  com->state &= ~CS_TTGO;
          else
                  com->state |= CS_TTGO;
          if (tp->t_state & TS_TBLOCK) {
                  if (com->mcr_image & MCR_RTS && com->state & CS_RTS_IFLOW)
                          outb(com->modem_ctl_port, com->mcr_image &= ~MCR_RTS);
          } else {
                  if (!(com->mcr_image & MCR_RTS) && com->iptr < com->ihighwater
                      && com->state & CS_RTS_IFLOW)
                          outb(com->modem_ctl_port, com->mcr_image |= MCR_RTS);
          }
          enable_intr();
          if (tp->t_state & (TS_TIMEOUT | TS_TTSTOP)) {
                  ttwwakeup(tp);
                  splx(s);
                  return;
          }
          if (tp->t_outq.c_cc != 0) {
                  struct lbq      *qp;
                  struct lbq      *next;
  
                  if (!com->obufs[0].l_queued) {
                          com->obufs[0].l_tail
                              = com->obuf1 + q_to_b(&tp->t_outq, com->obuf1,
                                                    sizeof com->obuf1);
                          com->obufs[0].l_next = NULL;
                          com->obufs[0].l_queued = TRUE;
                          disable_intr();
                          if (com->state & CS_BUSY) {
                                  qp = com->obufq.l_next;
                                  while ((next = qp->l_next) != NULL)
                                          qp = next;
                                  qp->l_next = &com->obufs[0];
                          } else {
                                  com->obufq.l_head = com->obufs[0].l_head;
                                  com->obufq.l_tail = com->obufs[0].l_tail;
                                  com->obufq.l_next = &com->obufs[0];
                                  com->state |= CS_BUSY;
                          }
                          enable_intr();
                  }
                  if (tp->t_outq.c_cc != 0 && !com->obufs[1].l_queued) {
                          com->obufs[1].l_tail
                              = com->obuf2 + q_to_b(&tp->t_outq, com->obuf2,
                                                    sizeof com->obuf2);
                          com->obufs[1].l_next = NULL;
                          com->obufs[1].l_queued = TRUE;
                          disable_intr();
                          if (com->state & CS_BUSY) {
                                  qp = com->obufq.l_next;
                                  while ((next = qp->l_next) != NULL)
                                          qp = next;
                                  qp->l_next = &com->obufs[1];
                          } else {
                                  com->obufq.l_head = com->obufs[1].l_head;
                                  com->obufq.l_tail = com->obufs[1].l_tail;
                                  com->obufq.l_next = &com->obufs[1];
                                  com->state |= CS_BUSY;
                          }
                          enable_intr();
                  }
                  tp->t_state |= TS_BUSY;
          }
          disable_intr();
          if (com->state >= (CS_BUSY | CS_TTGO))
                  siointr1(com);  /* fake interrupt to start output */
          enable_intr();
          ttwwakeup(tp);
          splx(s);
  }
  
  static void
  siostop(tp, rw)
          struct tty      *tp;
          int             rw;
  {
          struct com_s    *com;
  
          com = com_addr(DEV_TO_UNIT(tp->t_dev));
          if (com->gone)
                  return;
          disable_intr();
          if (rw & FWRITE) {
                  if (com->hasfifo)
  #ifdef COM_ESP
                      /* XXX avoid h/w bug. */
                      if (!com->esp)
  #endif
                          /* XXX does this flush everything? */
                          outb(com->iobase + com_fifo,
                               FIFO_XMT_RST | com->fifo_image);
                  com->obufs[0].l_queued = FALSE;
                  com->obufs[1].l_queued = FALSE;
                  if (com->state & CS_ODONE)
                          com_events -= LOTS_OF_EVENTS;
                  com->state &= ~(CS_ODONE | CS_BUSY);
                  com->tp->t_state &= ~TS_BUSY;
          }
          if (rw & FREAD) {
                  if (com->hasfifo)
  #ifdef COM_ESP
                      /* XXX avoid h/w bug. */
                      if (!com->esp)
  #endif
                          /* XXX does this flush everything? */
                          outb(com->iobase + com_fifo,
                               FIFO_RCV_RST | com->fifo_image);
                  com_events -= (com->iptr - com->ibuf);
                  com->iptr = com->ibuf;
          }
          enable_intr();
          comstart(tp);
  }
  
  static struct tty *
  siodevtotty(dev)
          dev_t   dev;
  {
          int     mynor;
          int     unit;
  
          mynor = minor(dev);
          if (mynor & CONTROL_MASK)
                  return (NULL);
          unit = MINOR_TO_UNIT(mynor);
          if ((u_int) unit >= NSIOTOT)
                  return (NULL);
          return (&sio_tty[unit]);
  }
  
  static int
  commctl(com, bits, how)
          struct com_s    *com;
          int             bits;
          int             how;
  {
          int     mcr;
          int     msr;
  
          if (how == DMGET) {
                  bits = TIOCM_LE;        /* XXX - always enabled while open */
                  mcr = com->mcr_image;
                  if (mcr & MCR_DTR)
                          bits |= TIOCM_DTR;
                  if (mcr & MCR_RTS)
                          bits |= TIOCM_RTS;
                  msr = com->prev_modem_status;
                  if (msr & MSR_CTS)
                          bits |= TIOCM_CTS;
                  if (msr & MSR_DCD)
                          bits |= TIOCM_CD;
                  if (msr & MSR_DSR)
                          bits |= TIOCM_DSR;
                  /*
                   * XXX - MSR_RI is naturally volatile, and we make MSR_TERI
                   * more volatile by reading the modem status a lot.  Perhaps
                   * we should latch both bits until the status is read here.
                   */
                  if (msr & (MSR_RI | MSR_TERI))
                          bits |= TIOCM_RI;
                  return (bits);
          }
          mcr = 0;
          if (bits & TIOCM_DTR)
                  mcr |= MCR_DTR;
          if (bits & TIOCM_RTS)
                  mcr |= MCR_RTS;
          if (com->gone)
                  return(0);
          disable_intr();
          switch (how) {
          case DMSET:
                  outb(com->modem_ctl_port,
                       com->mcr_image = mcr | (com->mcr_image & MCR_IENABLE));
                  break;
          case DMBIS:
                  outb(com->modem_ctl_port, com->mcr_image |= mcr);
                  break;
          case DMBIC:
                  outb(com->modem_ctl_port, com->mcr_image &= ~mcr);
                  break;
          }
          enable_intr();
          return (0);
  }
  
  static void
  siosettimeout()
  {
          struct com_s    *com;
          bool_t          someopen;
          int             unit;
  
          /*
           * Set our timeout period to 1 second if no polled devices are open.
           * Otherwise set it to max(1/200, 1/hz).
           * Enable timeouts iff some device is open.
           */
          untimeout(comwakeup, (void *)NULL, sio_timeout_handle);
          sio_timeout = hz;
          someopen = FALSE;
          for (unit = 0; unit < NSIOTOT; ++unit) {
                  com = com_addr(unit);
                  if (com != NULL && com->tp != NULL
                      && com->tp->t_state & TS_ISOPEN && !com->gone) {
                          someopen = TRUE;
                          if (com->poll || com->poll_output) {
                                  sio_timeout = hz > 200 ? hz / 200 : 1;
                                  break;
                          }
                  }
          }
          if (someopen) {
                  sio_timeouts_until_log = hz / sio_timeout;
                  sio_timeout_handle = timeout(comwakeup, (void *)NULL,
                                               sio_timeout);
          } else {
                  /* Flush error messages, if any. */
                  sio_timeouts_until_log = 1;
                  comwakeup((void *)NULL);
                  untimeout(comwakeup, (void *)NULL, sio_timeout_handle);
          }
  }
  
  static void
  comwakeup(chan)
          void    *chan;
  {
          struct com_s    *com;
          int             unit;
  
          sio_timeout_handle = timeout(comwakeup, (void *)NULL, sio_timeout);
  
          /*
           * Recover from lost output interrupts.
           * Poll any lines that don't use interrupts.
           */
          for (unit = 0; unit < NSIOTOT; ++unit) {
                  com = com_addr(unit);
                  if (com != NULL && !com->gone
                      && (com->state >= (CS_BUSY | CS_TTGO) || com->poll)) {
                          disable_intr();
                          siointr1(com);
                          enable_intr();
                  }
          }
  
          /*
           * Check for and log errors, but not too often.
           */
          if (--sio_timeouts_until_log > 0)
                  return;
          sio_timeouts_until_log = hz / sio_timeout;
          for (unit = 0; unit < NSIOTOT; ++unit) {
                  int     errnum;
  
                  com = com_addr(unit);
                  if (com == NULL)
                          continue;
                  if (com->gone)
                          continue;
                  for (errnum = 0; errnum < CE_NTYPES; ++errnum) {
                          u_int   delta;
                          u_long  total;
  
                          disable_intr();
                          delta = com->delta_error_counts[errnum];
                          com->delta_error_counts[errnum] = 0;
                          enable_intr();
                          if (delta == 0)
                                  continue;
                          total = com->error_counts[errnum] += delta;
                          log(LOG_ERR, "sio%d: %u more %s%s (total %lu)\n",
                              unit, delta, error_desc[errnum],
                              delta == 1 ? "" : "s", total);
                  }
          }
  }
  
  static void
  disc_optim(tp, t, com)
          struct tty      *tp;
          struct termios  *t;
          struct com_s    *com;
  {
          if (!(t->c_iflag & (ICRNL | IGNCR | IMAXBEL | INLCR | ISTRIP | IXON))
              && (!(t->c_iflag & BRKINT) || (t->c_iflag & IGNBRK))
              && (!(t->c_iflag & PARMRK)
                  || (t->c_iflag & (IGNPAR | IGNBRK)) == (IGNPAR | IGNBRK))
              && !(t->c_lflag & (ECHO | ICANON | IEXTEN | ISIG | PENDIN))
              && linesw[tp->t_line].l_rint == ttyinput)
                  tp->t_state |= TS_CAN_BYPASS_L_RINT;
          else
                  tp->t_state &= ~TS_CAN_BYPASS_L_RINT;
          com->hotchar = linesw[tp->t_line].l_hotchar;
  }
  
  /*
   * Following are all routines needed for SIO to act as console
   */
  #include <machine/cons.h>
  
  struct siocnstate {
          u_char  dlbl;
          u_char  dlbh;
          u_char  ier;
          u_char  cfcr;
          u_char  mcr;
  };
  
  static speed_t siocngetspeed __P((Port_t, struct speedtab *));
  static void siocnclose  __P((struct siocnstate *sp, Port_t iobase));
  static void siocnopen   __P((struct siocnstate *sp, Port_t iobase, int speed));
  static void siocntxwait __P((Port_t iobase));
  
  static void
  siocntxwait(iobase)
          Port_t  iobase;
  {
          int     timo;
  
          /*
           * Wait for any pending transmission to finish.  Required to avoid
           * the UART lockup bug when the speed is changed, and for normal
           * transmits.
           */
          timo = 100000;
          while ((inb(iobase + com_lsr) & (LSR_TSRE | LSR_TXRDY))
                 != (LSR_TSRE | LSR_TXRDY) && --timo != 0)
                  ;
  }
  
  /*
   * Read the serial port specified and try to figure out what speed
   * it's currently running at.  We're assuming the serial port has
   * been initialized and is basicly idle.  This routine is only intended
   * to be run at system startup.
   *
   * If the value read from the serial port doesn't make sense, return 0.
   */
  
  static speed_t
  siocngetspeed(iobase, table)
          Port_t iobase;
          struct speedtab *table;
  {
          int     code;
          u_char  dlbh;
          u_char  dlbl;
          u_char  cfcr;
  
          cfcr = inb(iobase + com_cfcr);
          outb(iobase + com_cfcr, CFCR_DLAB | cfcr);
  
          dlbl = inb(iobase + com_dlbl);
          dlbh = inb(iobase + com_dlbh);
  
          outb(iobase + com_cfcr, cfcr);
  
          code = dlbh << 8 | dlbl;
  
          for ( ; table->sp_speed != -1; table++)
                  if (table->sp_code == code)
                          return (table->sp_speed);
  
          return 0;       /* didn't match anything sane */
  }
  
  static void
  siocnopen(sp, iobase, speed)
          struct siocnstate       *sp;
          Port_t                  iobase;
          int                     speed;
  {
          int     divisor;
          u_char  dlbh;
          u_char  dlbl;
  
          /*
           * Save all the device control registers except the fifo register
           * and set our default ones (cs8 -parenb speed=comdefaultrate).
           * We can't save the fifo register since it is read-only.
           */
          sp->ier = inb(iobase + com_ier);
          outb(iobase + com_ier, 0);      /* spltty() doesn't stop siointr() */
          siocntxwait(iobase);
          sp->cfcr = inb(iobase + com_cfcr);
          outb(iobase + com_cfcr, CFCR_DLAB | CFCR_8BITS);
          sp->dlbl = inb(iobase + com_dlbl);
          sp->dlbh = inb(iobase + com_dlbh);
          /*
           * Only set the divisor registers if they would change, since on
           * some 16550 incompatibles (Startech), setting them clears the
           * data input register.  This also reduces the effects of the
           * UMC8669F bug.
           */
          divisor = ttspeedtab(speed, comspeedtab);
          dlbl = divisor & 0xFF;
          if (sp->dlbl != dlbl)
                  outb(iobase + com_dlbl, dlbl);
          dlbh = (u_int) divisor >> 8;
          if (sp->dlbh != dlbh)
                  outb(iobase + com_dlbh, dlbh);
          outb(iobase + com_cfcr, CFCR_8BITS);
          sp->mcr = inb(iobase + com_mcr);
          /*
           * We don't want interrupts, but must be careful not to "disable"
           * them by clearing the MCR_IENABLE bit, since that might cause
           * an interrupt by floating the IRQ line.
           */
          outb(iobase + com_mcr, (sp->mcr & MCR_IENABLE) | MCR_DTR | MCR_RTS);
  }
  
  static void
  siocnclose(sp, iobase)
          struct siocnstate       *sp;
          Port_t                  iobase;
  {
          /*
           * Restore the device control registers.
           */
          siocntxwait(iobase);
          outb(iobase + com_cfcr, CFCR_DLAB | CFCR_8BITS);
          if (sp->dlbl != inb(iobase + com_dlbl))
                  outb(iobase + com_dlbl, sp->dlbl);
          if (sp->dlbh != inb(iobase + com_dlbh))
                  outb(iobase + com_dlbh, sp->dlbh);
          outb(iobase + com_cfcr, sp->cfcr);
          /*
           * XXX damp oscillations of MCR_DTR and MCR_RTS by not restoring them.
           */
          outb(iobase + com_mcr, sp->mcr | MCR_DTR | MCR_RTS);
          outb(iobase + com_ier, sp->ier);
  }
  
  void
  siocnprobe(cp)
          struct consdev  *cp;
  {
  #if 0
          speed_t                 boot_speed;
          u_char                  cfcr;
          struct isa_device       *dvp;
          int                     s;
          struct siocnstate       sp;
  
          /*
           * Find our first enabled console, if any.  If it is a high-level
           * console device, then initialize it and return successfully.
           * If it is a low-level console device, then initialize it and
           * return unsuccessfully.  It must be initialized in both cases
           * for early use by console drivers and debuggers.  Initializing
           * the hardware is not necessary in all cases, since the i/o
           * routines initialize it on the fly, but it is necessary if
           * input might arrive while the hardware is switched back to an
           * uninitialized state.  We can't handle multiple console devices
           * yet because our low-level routines don't take a device arg.
           * We trust the user to set the console flags properly so that we
           * don't need to probe.
           */
          cp->cn_pri = CN_DEAD;
          for (dvp = isa_devtab_tty; dvp->id_driver != NULL; dvp++)
                  if (dvp->id_driver == &siodriver && dvp->id_enabled
                      && COM_CONSOLE(dvp)) {
                          siocniobase = dvp->id_iobase;
                          s = spltty();
                          if (boothowto & RB_SERIAL) {
                                  boot_speed = siocngetspeed(siocniobase,
                                                             comspeedtab);
                                  if (boot_speed)
                                          comdefaultrate = boot_speed;
                          }
  
                          /*
                           * Initialize the divisor latch.  We can't rely on
                           * siocnopen() to do this the first time, since it 
                           * avoids writing to the latch if the latch appears
                           * to have the correct value.  Also, if we didn't
                           * just read the speed from the hardware, then we
                           * need to set the speed in hardware so that
                           * switching it later is null.
                           */
                          cfcr = inb(siocniobase + com_cfcr);
                          outb(siocniobase + com_cfcr, CFCR_DLAB | cfcr);
                          outb(siocniobase + com_dlbl,
                               COMBRD(comdefaultrate) & 0xff);
                          outb(siocniobase + com_dlbh,
                               (u_int) COMBRD(comdefaultrate) >> 8);
                          outb(siocniobase + com_cfcr, cfcr);
  
                          siocnopen(&sp, siocniobase, comdefaultrate);
                          splx(s);
                          if (!COM_LLCONSOLE(dvp)) {
                                  cp->cn_dev = makedev(CDEV_MAJOR, dvp->id_unit);
                                  cp->cn_pri = COM_FORCECONSOLE(dvp)
                                               || boothowto & RB_SERIAL
                                               ? CN_REMOTE : CN_NORMAL;
                          }
                          break;
                  }
  #endif
  }
  
  struct consdev siocons = {
          NULL, NULL, siocngetc, siocncheckc, siocnputc,
          NULL, makedev(CDEV_MAJOR, 0), CN_NORMAL,
  };
  
  extern struct consdev *cn_tab;
  
  int
  siocnattach(port, speed)
          int port;
          int speed;
  {
          int                     s;
          u_char                  cfcr;
          struct siocnstate       sp;
  
          siocniobase = port;
          comdefaultrate = speed;
  
          s = spltty();
  
          /*
           * Initialize the divisor latch.  We can't rely on
           * siocnopen() to do this the first time, since it 
           * avoids writing to the latch if the latch appears
           * to have the correct value.  Also, if we didn't
           * just read the speed from the hardware, then we
           * need to set the speed in hardware so that
           * switching it later is null.
           */
          cfcr = inb(siocniobase + com_cfcr);
          outb(siocniobase + com_cfcr, CFCR_DLAB | cfcr);
          outb(siocniobase + com_dlbl,
               COMBRD(comdefaultrate) & 0xff);
          outb(siocniobase + com_dlbh,
               (u_int) COMBRD(comdefaultrate) >> 8);
          outb(siocniobase + com_cfcr, cfcr);
  
          siocnopen(&sp, siocniobase, comdefaultrate);
          splx(s);
  
          cn_tab = &siocons;
          return 0;
  }
  
  int
  siogdbattach(port, speed)
          int port;
          int speed;
  {
          int                     s;
          u_char                  cfcr;
          struct siocnstate       sp;
  
          siogdbiobase = port;
          gdbdefaultrate = speed;
  
          s = spltty();
  
          /*
           * Initialize the divisor latch.  We can't rely on
           * siocnopen() to do this the first time, since it 
           * avoids writing to the latch if the latch appears
           * to have the correct value.  Also, if we didn't
           * just read the speed from the hardware, then we
           * need to set the speed in hardware so that
           * switching it later is null.
           */
          cfcr = inb(siogdbiobase + com_cfcr);
          outb(siogdbiobase + com_cfcr, CFCR_DLAB | cfcr);
          outb(siogdbiobase + com_dlbl,
               COMBRD(gdbdefaultrate) & 0xff);
          outb(siogdbiobase + com_dlbh,
               (u_int) COMBRD(gdbdefaultrate) >> 8);
          outb(siogdbiobase + com_cfcr, cfcr);
  
          siocnopen(&sp, siogdbiobase, gdbdefaultrate);
          splx(s);
  
          return 0;
  }
  
  void
  siocninit(cp)
          struct consdev  *cp;
  {
          comconsole = DEV_TO_UNIT(cp->cn_dev);
  }
  
  int
  siocncheckc(dev)
          dev_t   dev;
  {
          int     c;
          Port_t  iobase;
          int     s;
          struct siocnstate       sp;
  
          iobase = siocniobase;
          s = spltty();
          siocnopen(&sp, iobase, comdefaultrate);
          if (inb(iobase + com_lsr) & LSR_RXRDY)
                  c = inb(iobase + com_data);
          else
                  c = -1;
          siocnclose(&sp, iobase);
          splx(s);
          return (c);
  }
  
  
  int
  siocngetc(dev)
          dev_t   dev;
  {
          int     c;
          Port_t  iobase;
          int     s;
          struct siocnstate       sp;
  
          iobase = siocniobase;
          s = spltty();
          siocnopen(&sp, iobase, comdefaultrate);
          while (!(inb(iobase + com_lsr) & LSR_RXRDY))
                  ;
          c = inb(iobase + com_data);
          siocnclose(&sp, iobase);
          splx(s);
          return (c);
  }
  
  void
  siocnputc(dev, c)
          dev_t   dev;
          int     c;
  {
          int     s;
          struct siocnstate       sp;
  
          s = spltty();
          siocnopen(&sp, siocniobase, comdefaultrate);
          siocntxwait(siocniobase);
          outb(siocniobase + com_data, c);
          siocnclose(&sp, siocniobase);
          splx(s);
  }
  
  int
  siogdbgetc()
  {
          int     c;
          Port_t  iobase;
          int     s;
          struct siocnstate       sp;
  
          iobase = siogdbiobase;
          s = spltty();
          siocnopen(&sp, iobase, gdbdefaultrate);
          while (!(inb(iobase + com_lsr) & LSR_RXRDY))
                  ;
          c = inb(iobase + com_data);
          siocnclose(&sp, iobase);
          splx(s);
          return (c);
  }
  
  void
  siogdbputc(c)
          int     c;
  {
          int     s;
          struct siocnstate       sp;
  
          s = spltty();
          siocnopen(&sp, siogdbiobase, gdbdefaultrate);
          siocntxwait(siogdbiobase);
          outb(siogdbiobase + com_data, c);
          siocnclose(&sp, siogdbiobase);
          splx(s);
  }
  
  #ifdef DSI_SOFT_MODEM
  /*
   * The magic code to download microcode to a "Connection 14.4+Fax"
   * modem from Digicom Systems Inc.  Very magic.
   */
  
  #define DSI_ERROR(str) { ptr = str; goto error; }
  static int
  LoadSoftModem(int unit, int base_io, u_long size, u_char *ptr)
  {
      int int_c,int_k;
      int data_0188, data_0187;
  
      /*
       * First see if it is a DSI SoftModem
       */
      if(!((inb(base_io+7) ^ inb(base_io+7)) & 0x80))
          return ENODEV;
  
      data_0188 = inb(base_io+4);
      data_0187 = inb(base_io+3);
      outb(base_io+3,0x80);
      outb(base_io+4,0x0C);
      outb(base_io+0,0x31);
      outb(base_io+1,0x8C);
      outb(base_io+7,0x10);
      outb(base_io+7,0x19);
  
      if(0x18 != (inb(base_io+7) & 0x1A))
          DSI_ERROR("dsp bus not granted");
  
      if(0x01 != (inb(base_io+7) & 0x01)) {
          outb(base_io+7,0x18);
          outb(base_io+7,0x19);
          if(0x01 != (inb(base_io+7) & 0x01))
              DSI_ERROR("program mem not granted");
      }
  
      int_c = 0;
  
      while(1) {
          if(int_c >= 7 || size <= 0x1800)
              break;
  
          for(int_k = 0 ; int_k < 0x800; int_k++) {
              outb(base_io+0,*ptr++);
              outb(base_io+1,*ptr++);
              outb(base_io+2,*ptr++);
          }
  
          size -= 0x1800;
          int_c++;
      }
  
      if(size > 0x1800) {
          outb(base_io+7,0x18);
          outb(base_io+7,0x19);
          if(0x00 != (inb(base_io+7) & 0x01))
              DSI_ERROR("program data not granted");
  
          for(int_k = 0 ; int_k < 0x800; int_k++) {
              outb(base_io+1,*ptr++);
              outb(base_io+2,0);
              outb(base_io+1,*ptr++);
              outb(base_io+2,*ptr++);
          }
  
          size -= 0x1800;
  
          while(size > 0x1800) {
              for(int_k = 0 ; int_k < 0xC00; int_k++) {
                  outb(base_io+1,*ptr++);
                  outb(base_io+2,*ptr++);
              }
              size -= 0x1800;
          }
  
          if(size < 0x1800) {
              for(int_k=0;int_k<size/2;int_k++) {
                  outb(base_io+1,*ptr++);
                  outb(base_io+2,*ptr++);
              }
          }
  
      } else if (size > 0) {
          if(int_c == 7) {
              outb(base_io+7,0x18);
              outb(base_io+7,0x19);
              if(0x00 != (inb(base_io+7) & 0x01))
                  DSI_ERROR("program data not granted");
              for(int_k = 0 ; int_k < size/3; int_k++) {
                  outb(base_io+1,*ptr++);
                  outb(base_io+2,0);
                  outb(base_io+1,*ptr++);
                  outb(base_io+2,*ptr++);
              }
          } else {
              for(int_k = 0 ; int_k < size/3; int_k++) {
                  outb(base_io+0,*ptr++);
                  outb(base_io+1,*ptr++);
                  outb(base_io+2,*ptr++);
              }
          }
      }
      outb(base_io+7,0x11);
      outb(base_io+7,3);
  
      outb(base_io+4,data_0188 & 0xfb);
  
      outb(base_io+3,data_0187);
  
      return 0;
  error:
      printf("sio%d: DSI SoftModem microcode load failed: <%s>\n",unit,ptr);
      outb(base_io+7,0x00); \
      outb(base_io+3,data_0187); \
      outb(base_io+4,data_0188);  \
      return EIO;
  }
  #endif /* DSI_SOFT_MODEM */
  
  /*
   * support PnP cards if we are using 'em
   */
  
  #if NPNP > 0
  
  static pnpid_t siopnp_ids[] = {
          { 0x5015f435, "MOT1550"},
          { 0x8113b04e, "Supra1381"},
          { 0x9012b04e, "Supra1290"},
          { 0x7121b04e, "SupraExpress 56i Sp"},
          { 0x11007256, "USR0011"},
          { 0x01017256, "USR0101"},
          { 0x30207256, "USR2030"},
          { 0x31307256, "USR3031"},
          { 0 }
  };
  
  static char *siopnp_probe(u_long csn, u_long vend_id);
  static void siopnp_attach(u_long csn, u_long vend_id, char *name,
          struct isa_device *dev);
  static u_long nsiopnp = NSIO;
  
  static struct pnp_device siopnp = {
          "siopnp",
          siopnp_probe,
          siopnp_attach,
          &nsiopnp,
          &tty_imask
  };
  DATA_SET (pnpdevice_set, siopnp);
  
  static char *
  siopnp_probe(u_long csn, u_long vend_id)
  {
          pnpid_t *id;
          char *s = NULL;
  
          for(id = siopnp_ids; id->vend_id != 0; id++) {
                  if (vend_id == id->vend_id) {
                          s = id->id_str;
                          break;
                  }
          }
  
          if (s) {
                  struct pnp_cinfo d;
                  read_pnp_parms(&d, 0);
                  if (d.enable == 0 || d.flags & 1) {
                          printf("CSN %lu is disabled.\n", csn);
                          return (NULL);
                  }
  
          }
  
          return (s);
  }
  
  static void
  siopnp_attach(u_long csn, u_long vend_id, char *name, struct isa_device *dev)
  {
          struct pnp_cinfo d;
          struct isa_device *dvp;
  
          if (dev->id_unit >= NSIOTOT)
                  return;
  
          if (read_pnp_parms(&d, 0) == 0) {
                  printf("failed to read pnp parms\n");
                  return;
          }
  
          write_pnp_parms(&d, 0);
  
          enable_pnp_card();
  
          dev->id_iobase = d.port[0];
          dev->id_irq = (1 << d.irq[0]);
          dev->id_intr = siointr;
          dev->id_ri_flags = RI_FAST;
          dev->id_drq = -1;
  
          if (dev->id_driver == NULL) {
                  dev->id_driver = &siodriver;
                  dvp = find_isadev(isa_devtab_tty, &siodriver, 0);
                  if (dvp != NULL)
                          dev->id_id = dvp->id_id;
          }
  
          if ((dev->id_alive = sioprobe(dev)) != 0)
                  sioattach(dev);
          else
                  printf("sio%d: probe failed\n", dev->id_unit);
  }
  #endif
  
  CDEV_DRIVER_MODULE(sio, isa, sio_driver, sio_devclass,
                     CDEV_MAJOR, sio_cdevsw, 0, 0);