FreeBSD/Linux Kernel Cross Reference
sys/x86/isa/atrtc.c

     /*-
      * Copyright (c) 2008 Poul-Henning Kamp
      * Copyright (c) 2010 Alexander Motin <mav@FreeBSD.org>
      * 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.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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: releng/10.2/sys/x86/isa/atrtc.c 285446 2015-07-13 11:58:08Z brueffer $
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/10.2/sys/x86/isa/atrtc.c 285446 2015-07-13 11:58:08Z brueffer $");
    
    #include "opt_isa.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bus.h>
    #include <sys/clock.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/kdb.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/proc.h>
    #include <sys/rman.h>
    #include <sys/timeet.h>
    
    #include <isa/rtc.h>
    #ifdef DEV_ISA
    #include <isa/isareg.h>
    #include <isa/isavar.h>
    #endif
    #include <machine/intr_machdep.h>
    #include "clock_if.h"
    
    #define RTC_LOCK        do { if (!kdb_active) mtx_lock_spin(&clock_lock); } while (0)
    #define RTC_UNLOCK      do { if (!kdb_active) mtx_unlock_spin(&clock_lock); } while (0)
    
    int     atrtcclock_disable = 0;
    
    static  int     rtc_reg = -1;
    static  u_char  rtc_statusa = RTCSA_DIVIDER | RTCSA_NOPROF;
    static  u_char  rtc_statusb = RTCSB_24HR;
    
    /*
     * RTC support routines
     */
    
    int
    rtcin(int reg)
    {
            u_char val;
    
            RTC_LOCK;
            if (rtc_reg != reg) {
                    inb(0x84);
                    outb(IO_RTC, reg);
                    rtc_reg = reg;
                    inb(0x84);
            }
            val = inb(IO_RTC + 1);
            RTC_UNLOCK;
            return (val);
    }
    
    void
    writertc(int reg, u_char val)
    {
    
            RTC_LOCK;
            if (rtc_reg != reg) {
                    inb(0x84);
                    outb(IO_RTC, reg);
                    rtc_reg = reg;
                    inb(0x84);
            }
            outb(IO_RTC + 1, val);
            inb(0x84);
            RTC_UNLOCK;
   }
   
   static __inline int
   readrtc(int port)
   {
           return(bcd2bin(rtcin(port)));
   }
   
   static void
   atrtc_start(void)
   {
   
           writertc(RTC_STATUSA, rtc_statusa);
           writertc(RTC_STATUSB, RTCSB_24HR);
   }
   
   static void
   atrtc_rate(unsigned rate)
   {
   
           rtc_statusa = RTCSA_DIVIDER | rate;
           writertc(RTC_STATUSA, rtc_statusa);
   }
   
   static void
   atrtc_enable_intr(void)
   {
   
           rtc_statusb |= RTCSB_PINTR;
           writertc(RTC_STATUSB, rtc_statusb);
           rtcin(RTC_INTR);
   }
   
   static void
   atrtc_disable_intr(void)
   {
   
           rtc_statusb &= ~RTCSB_PINTR;
           writertc(RTC_STATUSB, rtc_statusb);
           rtcin(RTC_INTR);
   }
   
   void
   atrtc_restore(void)
   {
   
           /* Restore all of the RTC's "status" (actually, control) registers. */
           rtcin(RTC_STATUSA);     /* dummy to get rtc_reg set */
           writertc(RTC_STATUSB, RTCSB_24HR);
           writertc(RTC_STATUSA, rtc_statusa);
           writertc(RTC_STATUSB, rtc_statusb);
           rtcin(RTC_INTR);
   }
   
   /**********************************************************************
    * RTC driver for subr_rtc
    */
   
   struct atrtc_softc {
           int port_rid, intr_rid;
           struct resource *port_res;
           struct resource *intr_res;
           void *intr_handler;
           struct eventtimer et;
   };
   
   static int
   rtc_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
   {
   
           atrtc_rate(max(fls(period + (period >> 1)) - 17, 1));
           atrtc_enable_intr();
           return (0);
   }
   
   static int
   rtc_stop(struct eventtimer *et)
   {
   
           atrtc_disable_intr();
           return (0);
   }
   
   /*
    * This routine receives statistical clock interrupts from the RTC.
    * As explained above, these occur at 128 interrupts per second.
    * When profiling, we receive interrupts at a rate of 1024 Hz.
    *
    * This does not actually add as much overhead as it sounds, because
    * when the statistical clock is active, the hardclock driver no longer
    * needs to keep (inaccurate) statistics on its own.  This decouples
    * statistics gathering from scheduling interrupts.
    *
    * The RTC chip requires that we read status register C (RTC_INTR)
    * to acknowledge an interrupt, before it will generate the next one.
    * Under high interrupt load, rtcintr() can be indefinitely delayed and
    * the clock can tick immediately after the read from RTC_INTR.  In this
    * case, the mc146818A interrupt signal will not drop for long enough
    * to register with the 8259 PIC.  If an interrupt is missed, the stat
    * clock will halt, considerably degrading system performance.  This is
    * why we use 'while' rather than a more straightforward 'if' below.
    * Stat clock ticks can still be lost, causing minor loss of accuracy
    * in the statistics, but the stat clock will no longer stop.
    */
   static int
   rtc_intr(void *arg)
   {
           struct atrtc_softc *sc = (struct atrtc_softc *)arg;
           int flag = 0;
   
           while (rtcin(RTC_INTR) & RTCIR_PERIOD) {
                   flag = 1;
                   if (sc->et.et_active)
                           sc->et.et_event_cb(&sc->et, sc->et.et_arg);
           }
           return(flag ? FILTER_HANDLED : FILTER_STRAY);
   }
   
   /*
    * Attach to the ISA PnP descriptors for the timer and realtime clock.
    */
   static struct isa_pnp_id atrtc_ids[] = {
           { 0x000bd041 /* PNP0B00 */, "AT realtime clock" },
           { 0 }
   };
   
   static int
   atrtc_probe(device_t dev)
   {
           int result;
           
           result = ISA_PNP_PROBE(device_get_parent(dev), dev, atrtc_ids);
           /* ENOENT means no PnP-ID, device is hinted. */
           if (result == ENOENT) {
                   device_set_desc(dev, "AT realtime clock");
                   return (BUS_PROBE_LOW_PRIORITY);
           }
           return (result);
   }
   
   static int
   atrtc_attach(device_t dev)
   {
           struct atrtc_softc *sc;
           u_long s;
           int i;
   
           sc = device_get_softc(dev);
           sc->port_res = bus_alloc_resource(dev, SYS_RES_IOPORT, &sc->port_rid,
               IO_RTC, IO_RTC + 1, 2, RF_ACTIVE);
           if (sc->port_res == NULL)
                   device_printf(dev, "Warning: Couldn't map I/O.\n");
           atrtc_start();
           clock_register(dev, 1000000);
           bzero(&sc->et, sizeof(struct eventtimer));
           if (!atrtcclock_disable &&
               (resource_int_value(device_get_name(dev), device_get_unit(dev),
                "clock", &i) != 0 || i != 0)) {
                   sc->intr_rid = 0;
                   while (bus_get_resource(dev, SYS_RES_IRQ, sc->intr_rid,
                       &s, NULL) == 0 && s != 8)
                           sc->intr_rid++;
                   sc->intr_res = bus_alloc_resource(dev, SYS_RES_IRQ,
                       &sc->intr_rid, 8, 8, 1, RF_ACTIVE);
                   if (sc->intr_res == NULL) {
                           device_printf(dev, "Can't map interrupt.\n");
                           return (0);
                   } else if ((bus_setup_intr(dev, sc->intr_res, INTR_TYPE_CLK,
                       rtc_intr, NULL, sc, &sc->intr_handler))) {
                           device_printf(dev, "Can't setup interrupt.\n");
                           return (0);
                   } else { 
                           /* Bind IRQ to BSP to avoid live migration. */
                           bus_bind_intr(dev, sc->intr_res, 0);
                   }
                   sc->et.et_name = "RTC";
                   sc->et.et_flags = ET_FLAGS_PERIODIC | ET_FLAGS_POW2DIV;
                   sc->et.et_quality = 0;
                   sc->et.et_frequency = 32768;
                   sc->et.et_min_period = 0x00080000;
                   sc->et.et_max_period = 0x80000000;
                   sc->et.et_start = rtc_start;
                   sc->et.et_stop = rtc_stop;
                   sc->et.et_priv = dev;
                   et_register(&sc->et);
           }
           return(0);
   }
   
   static int
   atrtc_resume(device_t dev)
   {
   
           atrtc_restore();
           return(0);
   }
   
   static int
   atrtc_settime(device_t dev __unused, struct timespec *ts)
   {
           struct clocktime ct;
   
           clock_ts_to_ct(ts, &ct);
   
           /* Disable RTC updates and interrupts. */
           writertc(RTC_STATUSB, RTCSB_HALT | RTCSB_24HR);
   
           writertc(RTC_SEC, bin2bcd(ct.sec));             /* Write back Seconds */
           writertc(RTC_MIN, bin2bcd(ct.min));             /* Write back Minutes */
           writertc(RTC_HRS, bin2bcd(ct.hour));            /* Write back Hours   */
   
           writertc(RTC_WDAY, ct.dow + 1);                 /* Write back Weekday */
           writertc(RTC_DAY, bin2bcd(ct.day));             /* Write back Day */
           writertc(RTC_MONTH, bin2bcd(ct.mon));           /* Write back Month   */
           writertc(RTC_YEAR, bin2bcd(ct.year % 100));     /* Write back Year    */
   #ifdef USE_RTC_CENTURY
           writertc(RTC_CENTURY, bin2bcd(ct.year / 100));  /* ... and Century    */
   #endif
   
           /* Reenable RTC updates and interrupts. */
           writertc(RTC_STATUSB, rtc_statusb);
           rtcin(RTC_INTR);
           return (0);
   }
   
   static int
   atrtc_gettime(device_t dev, struct timespec *ts)
   {
           struct clocktime ct;
   
           /* Look if we have a RTC present and the time is valid */
           if (!(rtcin(RTC_STATUSD) & RTCSD_PWR)) {
                   device_printf(dev, "WARNING: Battery failure indication\n");
                   return (EINVAL);
           }
   
           /*
            * wait for time update to complete
            * If RTCSA_TUP is zero, we have at least 244us before next update.
            * This is fast enough on most hardware, but a refinement would be
            * to make sure that no more than 240us pass after we start reading,
            * and try again if so.
            */
           while (rtcin(RTC_STATUSA) & RTCSA_TUP)
                   continue;
           critical_enter();
           ct.nsec = 0;
           ct.sec = readrtc(RTC_SEC);
           ct.min = readrtc(RTC_MIN);
           ct.hour = readrtc(RTC_HRS);
           ct.day = readrtc(RTC_DAY);
           ct.dow = readrtc(RTC_WDAY) - 1;
           ct.mon = readrtc(RTC_MONTH);
           ct.year = readrtc(RTC_YEAR);
   #ifdef USE_RTC_CENTURY
           ct.year += readrtc(RTC_CENTURY) * 100;
   #else
           ct.year += (ct.year < 80 ? 2000 : 1900);
   #endif
           critical_exit();
           /* Set dow = -1 because some clocks don't set it correctly. */
           ct.dow = -1;
           return (clock_ct_to_ts(&ct, ts));
   }
   
   static device_method_t atrtc_methods[] = {
           /* Device interface */
           DEVMETHOD(device_probe,         atrtc_probe),
           DEVMETHOD(device_attach,        atrtc_attach),
           DEVMETHOD(device_detach,        bus_generic_detach),
           DEVMETHOD(device_shutdown,      bus_generic_shutdown),
           DEVMETHOD(device_suspend,       bus_generic_suspend),
                   /* XXX stop statclock? */
           DEVMETHOD(device_resume,        atrtc_resume),
   
           /* clock interface */
           DEVMETHOD(clock_gettime,        atrtc_gettime),
           DEVMETHOD(clock_settime,        atrtc_settime),
   
           { 0, 0 }
   };
   
   static driver_t atrtc_driver = {
           "atrtc",
           atrtc_methods,
           sizeof(struct atrtc_softc),
   };
   
   static devclass_t atrtc_devclass;
   
   DRIVER_MODULE(atrtc, isa, atrtc_driver, atrtc_devclass, 0, 0);
   DRIVER_MODULE(atrtc, acpi, atrtc_driver, atrtc_devclass, 0, 0);
   
   #include "opt_ddb.h"
   #ifdef DDB
   #include <ddb/ddb.h>
   
   DB_SHOW_COMMAND(rtc, rtc)
   {
           printf("%02x/%02x/%02x %02x:%02x:%02x, A = %02x, B = %02x, C = %02x\n",
                   rtcin(RTC_YEAR), rtcin(RTC_MONTH), rtcin(RTC_DAY),
                   rtcin(RTC_HRS), rtcin(RTC_MIN), rtcin(RTC_SEC),
                   rtcin(RTC_STATUSA), rtcin(RTC_STATUSB), rtcin(RTC_INTR));
   }
   #endif /* DDB */

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