FreeBSD/Linux Kernel Cross Reference
sys/dev/raid/twe/twe_freebsd.c

     /*-
      * Copyright (c) 2000 Michael Smith
      * Copyright (c) 2003 Paul Saab
      * Copyright (c) 2003 Vinod Kashyap
      * Copyright (c) 2000 BSDi
      * 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: src/sys/dev/twe/twe_freebsd.c,v 1.54 2012/11/17 01:52:19 svnexp Exp $
     */
    
    /*
     * FreeBSD-specific code.
     */
    
    #include <dev/raid/twe/twe_compat.h>
    #include <dev/raid/twe/twereg.h>
    #include <dev/raid/twe/tweio.h>
    #include <dev/raid/twe/twevar.h>
    #include <dev/raid/twe/twe_tables.h>
    #include <sys/dtype.h>
    #include <sys/mplock2.h>
    
    #include <vm/vm.h>
    
    static devclass_t       twe_devclass;
    
    #ifdef TWE_DEBUG
    static u_int32_t        twed_bio_in;
    #define TWED_BIO_IN     twed_bio_in++
    static u_int32_t        twed_bio_out;
    #define TWED_BIO_OUT    twed_bio_out++
    #else
    #define TWED_BIO_IN
    #define TWED_BIO_OUT
    #endif
    
    static void     twe_setup_data_dmamap(void *arg, bus_dma_segment_t *segs, int nsegments, int error);
    static void     twe_setup_request_dmamap(void *arg, bus_dma_segment_t *segs, int nsegments, int error);
    
    /********************************************************************************
     ********************************************************************************
                                                             Control device interface
     ********************************************************************************
     ********************************************************************************/
    
    static  d_open_t                twe_open;
    static  d_close_t               twe_close;
    static  d_ioctl_t               twe_ioctl_wrapper;
    
    static struct dev_ops twe_ops = {
            { "twe", 0, D_MPSAFE },
            .d_open =       twe_open,
            .d_close =      twe_close,
            .d_ioctl =      twe_ioctl_wrapper,
    };
    
    /********************************************************************************
     * Accept an open operation on the control device.
     */
    static int
    twe_open(struct dev_open_args *ap)
    {
        cdev_t                      dev = ap->a_head.a_dev;
        struct twe_softc            *sc = (struct twe_softc *)dev->si_drv1;
    
        TWE_IO_LOCK(sc);
        if (sc->twe_state & TWE_STATE_DETACHING) {
            TWE_IO_UNLOCK(sc);
            return (ENXIO);
        }
        sc->twe_state |= TWE_STATE_OPEN;
        TWE_IO_UNLOCK(sc);
        return(0);
    }
    
    /********************************************************************************
     * Accept the last close on the control device.
     */
   static int
   twe_close(struct dev_close_args *ap)
   {
       cdev_t                      dev = ap->a_head.a_dev;
       struct twe_softc            *sc = (struct twe_softc *)dev->si_drv1;
   
       TWE_IO_LOCK(sc);
       sc->twe_state &= ~TWE_STATE_OPEN;
       TWE_IO_UNLOCK(sc);
       return (0);
   }
   
   /********************************************************************************
    * Handle controller-specific control operations.
    */
   static int
   twe_ioctl_wrapper(struct dev_ioctl_args *ap)
   {
       cdev_t dev = ap->a_head.a_dev;
       u_long cmd = ap->a_cmd;
       caddr_t addr = ap->a_data;
       struct twe_softc *sc = (struct twe_softc *)dev->si_drv1;
       
       return(twe_ioctl(sc, cmd, addr));
   }
   
   /********************************************************************************
    ********************************************************************************
                                                                PCI device interface
    ********************************************************************************
    ********************************************************************************/
   
   static int      twe_probe(device_t dev);
   static int      twe_attach(device_t dev);
   static void     twe_free(struct twe_softc *sc);
   static int      twe_detach(device_t dev);
   static int      twe_shutdown(device_t dev);
   static int      twe_suspend(device_t dev);
   static int      twe_resume(device_t dev);
   static void     twe_pci_intr(void *arg);
   static void     twe_intrhook(void *arg);
   
   static device_method_t twe_methods[] = {
       /* Device interface */
       DEVMETHOD(device_probe,     twe_probe),
       DEVMETHOD(device_attach,    twe_attach),
       DEVMETHOD(device_detach,    twe_detach),
       DEVMETHOD(device_shutdown,  twe_shutdown),
       DEVMETHOD(device_suspend,   twe_suspend),
       DEVMETHOD(device_resume,    twe_resume),
   
       DEVMETHOD_END
   };
   
   static driver_t twe_pci_driver = {
           "twe",
           twe_methods,
           sizeof(struct twe_softc)
   };
   
   DRIVER_MODULE(twe, pci, twe_pci_driver, twe_devclass, NULL, NULL);
   
   /********************************************************************************
    * Match a 3ware Escalade ATA RAID controller.
    */
   static int
   twe_probe(device_t dev)
   {
   
       debug_called(4);
   
       if ((pci_get_vendor(dev) == TWE_VENDOR_ID) &&
           ((pci_get_device(dev) == TWE_DEVICE_ID) || 
            (pci_get_device(dev) == TWE_DEVICE_ID_ASIC))) {
           device_set_desc_copy(dev, TWE_DEVICE_NAME ". Driver version " TWE_DRIVER_VERSION_STRING);
           return(BUS_PROBE_DEFAULT);
       }
       return(ENXIO);
   }
   
   /********************************************************************************
    * Allocate resources, initialise the controller.
    */
   static int
   twe_attach(device_t dev)
   {
       struct twe_softc    *sc;
       int                 rid, error;
   
       debug_called(4);
   
       /*
        * Initialise the softc structure.
        */
       sc = device_get_softc(dev);
       sc->twe_dev = dev;
       lockinit(&sc->twe_io_lock, "twe I/O", 0, LK_CANRECURSE);
       lockinit(&sc->twe_config_lock, "twe config", 0, LK_CANRECURSE);
   
       sysctl_ctx_init(&sc->sysctl_ctx);
       sc->sysctl_tree = SYSCTL_ADD_NODE(&sc->sysctl_ctx,
           SYSCTL_STATIC_CHILDREN(_hw), OID_AUTO,
           device_get_nameunit(dev), CTLFLAG_RD, 0, "");
       if (sc->sysctl_tree == NULL) {
           twe_printf(sc, "cannot add sysctl tree node\n");
           return (ENXIO);
       }
       SYSCTL_ADD_STRING(&sc->sysctl_ctx, SYSCTL_CHILDREN(sc->sysctl_tree),
           OID_AUTO, "driver_version", CTLFLAG_RD, TWE_DRIVER_VERSION_STRING, 0,
           "TWE driver version");
   
       /*
        * Force the busmaster enable bit on, in case the BIOS forgot.
        */
       pci_enable_busmaster(dev);
   
       /*
        * Allocate the PCI register window.
        */
       rid = TWE_IO_CONFIG_REG;
       if ((sc->twe_io = bus_alloc_resource_any(dev, SYS_RES_IOPORT, &rid,
           RF_ACTIVE)) == NULL) {
           twe_printf(sc, "can't allocate register window\n");
           twe_free(sc);
           return(ENXIO);
       }
   
       /*
        * Allocate the parent bus DMA tag appropriate for PCI.
        */
       if (bus_dma_tag_create(NULL,                                /* parent */
                              1, 0,                                /* alignment, boundary */
                              BUS_SPACE_MAXADDR_32BIT,             /* lowaddr */
                              BUS_SPACE_MAXADDR,                   /* highaddr */
                              NULL, NULL,                          /* filter, filterarg */
                              MAXBSIZE, TWE_MAX_SGL_LENGTH,        /* maxsize, nsegments */
                              BUS_SPACE_MAXSIZE_32BIT,             /* maxsegsize */
                              0,                                   /* flags */
                              &sc->twe_parent_dmat)) {
           twe_printf(sc, "can't allocate parent DMA tag\n");
           twe_free(sc);
           return(ENOMEM);
       }
   
       /* 
        * Allocate and connect our interrupt.
        */
       rid = 0;
       if ((sc->twe_irq = bus_alloc_resource_any(sc->twe_dev, SYS_RES_IRQ,
           &rid, RF_SHAREABLE | RF_ACTIVE)) == NULL) {
           twe_printf(sc, "can't allocate interrupt\n");
           twe_free(sc);
           return(ENXIO);
       }
       if (bus_setup_intr(sc->twe_dev, sc->twe_irq, INTR_MPSAFE,
                           twe_pci_intr, sc, &sc->twe_intr, NULL)) {
           twe_printf(sc, "can't set up interrupt\n");
           twe_free(sc);
           return(ENXIO);
       }
   
       /*
        * Create DMA tag for mapping command's into controller-addressable space.
        */
       if (bus_dma_tag_create(sc->twe_parent_dmat,         /* parent */
                              1, 0,                        /* alignment, boundary */
                              BUS_SPACE_MAXADDR_32BIT,     /* lowaddr */
                              BUS_SPACE_MAXADDR,           /* highaddr */
                              NULL, NULL,                  /* filter, filterarg */
                              sizeof(TWE_Command) *
                              TWE_Q_LENGTH, 1,             /* maxsize, nsegments */
                              BUS_SPACE_MAXSIZE_32BIT,     /* maxsegsize */
                              0,                           /* flags */
                              &sc->twe_cmd_dmat)) {
           twe_printf(sc, "can't allocate data buffer DMA tag\n");
           twe_free(sc);
           return(ENOMEM);
       }
       /*
        * Allocate memory and make it available for DMA.
        */
       if (bus_dmamem_alloc(sc->twe_cmd_dmat, (void **)&sc->twe_cmd,
                            BUS_DMA_NOWAIT, &sc->twe_cmdmap)) {
           twe_printf(sc, "can't allocate command memory\n");
           return(ENOMEM);
       }
       bus_dmamap_load(sc->twe_cmd_dmat, sc->twe_cmdmap, sc->twe_cmd,
                       sizeof(TWE_Command) * TWE_Q_LENGTH,
                       twe_setup_request_dmamap, sc, 0);
       bzero(sc->twe_cmd, sizeof(TWE_Command) * TWE_Q_LENGTH);
   
       /*
        * Create DMA tag for mapping objects into controller-addressable space.
        */
       if (bus_dma_tag_create(sc->twe_parent_dmat,         /* parent */
                              1, 0,                        /* alignment, boundary */
                              BUS_SPACE_MAXADDR_32BIT,     /* lowaddr */
                              BUS_SPACE_MAXADDR,           /* highaddr */
                              NULL, NULL,                  /* filter, filterarg */
                              MAXBSIZE, TWE_MAX_SGL_LENGTH,/* maxsize, nsegments */
                              BUS_SPACE_MAXSIZE_32BIT,     /* maxsegsize */
                              BUS_DMA_ALLOCNOW,            /* flags */
                              &sc->twe_buffer_dmat)) {
           twe_printf(sc, "can't allocate data buffer DMA tag\n");
           twe_free(sc);
           return(ENOMEM);
       }
   
       /*
        * Create DMA tag for mapping objects into controller-addressable space.
        */
       if (bus_dma_tag_create(sc->twe_parent_dmat,         /* parent */
                              1, 0,                        /* alignment, boundary */
                              BUS_SPACE_MAXADDR_32BIT,     /* lowaddr */
                              BUS_SPACE_MAXADDR,           /* highaddr */
                              NULL, NULL,                  /* filter, filterarg */
                              MAXBSIZE, 1,                 /* maxsize, nsegments */
                              BUS_SPACE_MAXSIZE_32BIT,     /* maxsegsize */
                              0,                           /* flags */
                              &sc->twe_immediate_dmat)) {
           twe_printf(sc, "can't allocate data buffer DMA tag\n");
           twe_free(sc);
           return(ENOMEM);
       }
       /*
        * Allocate memory for requests which cannot sleep or support continuation.
        */
        if (bus_dmamem_alloc(sc->twe_immediate_dmat, (void **)&sc->twe_immediate,
                             BUS_DMA_NOWAIT, &sc->twe_immediate_map)) {
           twe_printf(sc, "can't allocate memory for immediate requests\n");
           return(ENOMEM);
        }
   
       /*
        * Initialise the controller and driver core.
        */
       if ((error = twe_setup(sc))) {
           twe_free(sc);
           return(error);
       }
   
       /*
        * Print some information about the controller and configuration.
        */
       twe_describe_controller(sc);
   
       /*
        * Create the control device.
        */
       sc->twe_dev_t = make_dev(&twe_ops, device_get_unit(sc->twe_dev),
                                UID_ROOT, GID_OPERATOR,
                                S_IRUSR | S_IWUSR, "twe%d",
                                device_get_unit(sc->twe_dev));
       sc->twe_dev_t->si_drv1 = sc;
   
       /*
        * Schedule ourselves to bring the controller up once interrupts are
        * available.  This isn't strictly necessary, since we disable
        * interrupts while probing the controller, but it is more in keeping
        * with common practice for other disk devices.
        */
       sc->twe_ich.ich_func = twe_intrhook;
       sc->twe_ich.ich_arg = sc;
       sc->twe_ich.ich_desc = "twe";
       if (config_intrhook_establish(&sc->twe_ich) != 0) {
           twe_printf(sc, "can't establish configuration hook\n");
           twe_free(sc);
           return(ENXIO);
       }
   
       return(0);
   }
   
   /********************************************************************************
    * Free all of the resources associated with (sc).
    *
    * Should not be called if the controller is active.
    */
   static void
   twe_free(struct twe_softc *sc)
   {
       struct twe_request  *tr;
   
       debug_called(4);
   
       /* throw away any command buffers */
       while ((tr = twe_dequeue_free(sc)) != NULL)
           twe_free_request(tr);
   
       if (sc->twe_cmd != NULL) {
           bus_dmamap_unload(sc->twe_cmd_dmat, sc->twe_cmdmap);
           bus_dmamem_free(sc->twe_cmd_dmat, sc->twe_cmd, sc->twe_cmdmap);
       }
   
       if (sc->twe_immediate != NULL) {
           bus_dmamap_unload(sc->twe_immediate_dmat, sc->twe_immediate_map);
           bus_dmamem_free(sc->twe_immediate_dmat, sc->twe_immediate,
                           sc->twe_immediate_map);
       }
   
       if (sc->twe_immediate_dmat)
           bus_dma_tag_destroy(sc->twe_immediate_dmat);
   
       /* destroy the data-transfer DMA tag */
       if (sc->twe_buffer_dmat)
           bus_dma_tag_destroy(sc->twe_buffer_dmat);
   
       /* disconnect the interrupt handler */
       if (sc->twe_intr)
           bus_teardown_intr(sc->twe_dev, sc->twe_irq, sc->twe_intr);
       if (sc->twe_irq != NULL)
           bus_release_resource(sc->twe_dev, SYS_RES_IRQ, 0, sc->twe_irq);
   
       /* destroy the parent DMA tag */
       if (sc->twe_parent_dmat)
           bus_dma_tag_destroy(sc->twe_parent_dmat);
   
       /* release the register window mapping */
       if (sc->twe_io != NULL)
           bus_release_resource(sc->twe_dev, SYS_RES_IOPORT, TWE_IO_CONFIG_REG, sc->twe_io);
   
       /* destroy control device */
       if (sc->twe_dev_t != NULL)
           destroy_dev(sc->twe_dev_t);
       dev_ops_remove_minor(&twe_ops, device_get_unit(sc->twe_dev));
   
       sysctl_ctx_free(&sc->sysctl_ctx);
       lockuninit(&sc->twe_config_lock);
       lockuninit(&sc->twe_io_lock);
   }
   
   /********************************************************************************
    * Disconnect from the controller completely, in preparation for unload.
    */
   static int
   twe_detach(device_t dev)
   {
       struct twe_softc    *sc = device_get_softc(dev);
   
       debug_called(4);
   
       TWE_IO_LOCK(sc);
       if (sc->twe_state & TWE_STATE_OPEN) {
           TWE_IO_UNLOCK(sc);
           return (EBUSY);
       }
       sc->twe_state |= TWE_STATE_DETACHING;
       TWE_IO_UNLOCK(sc);
   
       /*  
        * Shut the controller down.
        */
       if (twe_shutdown(dev)) {
           TWE_IO_LOCK(sc);
           sc->twe_state &= ~TWE_STATE_DETACHING;
           TWE_IO_UNLOCK(sc);
           return (EBUSY);
       }
   
       twe_free(sc);
   
       return(0);
   }
   
   /********************************************************************************
    * Bring the controller down to a dormant state and detach all child devices.
    *
    * Note that we can assume that the bioq on the controller is empty, as we won't
    * allow shutdown if any device is open.
    */
   static int
   twe_shutdown(device_t dev)
   {
       struct twe_softc    *sc = device_get_softc(dev);
       int                 i, error = 0;
   
       debug_called(4);
   
       /* 
        * Delete all our child devices.
        */
       TWE_CONFIG_LOCK(sc);
       for (i = 0; i < TWE_MAX_UNITS; i++) {
           if (sc->twe_drive[i].td_disk != 0) {
               if ((error = twe_detach_drive(sc, i)) != 0) {
                   TWE_CONFIG_UNLOCK(sc);
                   return (error);
               }
           }
       }
       TWE_CONFIG_UNLOCK(sc);
   
       /*
        * Bring the controller down.
        */
       TWE_IO_LOCK(sc);
       twe_deinit(sc);
       TWE_IO_UNLOCK(sc);
   
       return(0);
   }
   
   /********************************************************************************
    * Bring the controller to a quiescent state, ready for system suspend.
    */
   static int
   twe_suspend(device_t dev)
   {
       struct twe_softc    *sc = device_get_softc(dev);
   
       debug_called(4);
   
       TWE_IO_LOCK(sc);
       sc->twe_state |= TWE_STATE_SUSPEND;
       TWE_IO_UNLOCK(sc);
       
       twe_disable_interrupts(sc);
       crit_exit();
   
       return(0);
   }
   
   /********************************************************************************
    * Bring the controller back to a state ready for operation.
    */
   static int
   twe_resume(device_t dev)
   {
       struct twe_softc    *sc = device_get_softc(dev);
   
       debug_called(4);
   
       TWE_IO_LOCK(sc);
       sc->twe_state &= ~TWE_STATE_SUSPEND;
       twe_enable_interrupts(sc);
       TWE_IO_UNLOCK(sc);
   
       return(0);
   }
   
   /*******************************************************************************
    * Take an interrupt, or be poked by other code to look for interrupt-worthy
    * status.
    */
   static void
   twe_pci_intr(void *arg)
   {
       struct twe_softc *sc = arg;
   
       TWE_IO_LOCK(sc);
       twe_intr(sc);
       TWE_IO_UNLOCK(sc);
   }
   
   /********************************************************************************
    * Delayed-startup hook
    */
   static void
   twe_intrhook(void *arg)
   {
       struct twe_softc            *sc = (struct twe_softc *)arg;
   
       /* pull ourselves off the intrhook chain */
       config_intrhook_disestablish(&sc->twe_ich);
   
       /* call core startup routine */
       twe_init(sc);
   }
   
   /********************************************************************************
    * Given a detected drive, attach it to the bio interface.
    *
    * This is called from twe_add_unit.
    */
   int
   twe_attach_drive(struct twe_softc *sc, struct twe_drive *dr)
   {
       char        buf[80];
       int         error;
   
       get_mplock();
       dr->td_disk =  device_add_child(sc->twe_dev, NULL, -1);
       if (dr->td_disk == NULL) {
           rel_mplock();
           twe_printf(sc, "Cannot add unit\n");
           return (EIO);
       }
       device_set_ivars(dr->td_disk, dr);
   
       /* 
        * XXX It would make sense to test the online/initialising bits, but they seem to be
        * always set...
        */
       ksprintf(buf, "Unit %d, %s, %s",
               dr->td_twe_unit,
               twe_describe_code(twe_table_unittype, dr->td_type),
               twe_describe_code(twe_table_unitstate, dr->td_state & TWE_PARAM_UNITSTATUS_MASK));
       device_set_desc_copy(dr->td_disk, buf);
   
       error = device_probe_and_attach(dr->td_disk);
       rel_mplock();
       if (error != 0) {
           twe_printf(sc, "Cannot attach unit to controller. error = %d\n", error);
           return (EIO);
       }
       return (0);
   }
   
   /********************************************************************************
    * Detach the specified unit if it exsists
    *
    * This is called from twe_del_unit.
    */
   int
   twe_detach_drive(struct twe_softc *sc, int unit)
   {
       int error = 0;
   
       TWE_CONFIG_ASSERT_LOCKED(sc);
       get_mplock();
       error = device_delete_child(sc->twe_dev, sc->twe_drive[unit].td_disk);
       rel_mplock();
       if (error != 0) {
           twe_printf(sc, "failed to delete unit %d\n", unit);
           return(error);
       }
       bzero(&sc->twe_drive[unit], sizeof(sc->twe_drive[unit]));
       return(error);
   }
   
   /********************************************************************************
    * Clear a PCI parity error.
    */
   void
   twe_clear_pci_parity_error(struct twe_softc *sc)
   {
       TWE_CONTROL(sc, TWE_CONTROL_CLEAR_PARITY_ERROR);
       pci_write_config(sc->twe_dev, PCIR_STATUS, TWE_PCI_CLEAR_PARITY_ERROR, 2);
   }
   
   /********************************************************************************
    * Clear a PCI abort.
    */
   void
   twe_clear_pci_abort(struct twe_softc *sc)
   {
       TWE_CONTROL(sc, TWE_CONTROL_CLEAR_PCI_ABORT);
       pci_write_config(sc->twe_dev, PCIR_STATUS, TWE_PCI_CLEAR_PCI_ABORT, 2);
   }
   
   /********************************************************************************
    ********************************************************************************
                                                                         Disk device
    ********************************************************************************
    ********************************************************************************/
   
   /*
    * Disk device bus interface
    */
   static int twed_probe(device_t dev);
   static int twed_attach(device_t dev);
   static int twed_detach(device_t dev);
   
   static device_method_t twed_methods[] = {
       DEVMETHOD(device_probe,     twed_probe),
       DEVMETHOD(device_attach,    twed_attach),
       DEVMETHOD(device_detach,    twed_detach),
       DEVMETHOD_END
   };
   
   static driver_t twed_driver = {
       "twed",
       twed_methods,
       sizeof(struct twed_softc)
   };
   
   static devclass_t       twed_devclass;
   DRIVER_MODULE(twed, twe, twed_driver, twed_devclass, NULL, NULL);
   
   /*
    * Disk device control interface.
    */
   static  d_open_t        twed_open;
   static  d_close_t       twed_close;
   static  d_strategy_t    twed_strategy;
   static  d_dump_t        twed_dump;
   
   static struct dev_ops twed_ops = {
           { "twed", 0, D_DISK | D_MPSAFE},
           .d_open =       twed_open,
           .d_close =      twed_close,
           .d_read =       physread,
           .d_write =      physwrite,
           .d_strategy =   twed_strategy,
           .d_dump =       twed_dump,
   };
   
   /********************************************************************************
    * Handle open from generic layer.
    *
    * Note that this is typically only called by the diskslice code, and not
    * for opens on subdevices (eg. slices, partitions).
    */
   static int
   twed_open(struct dev_open_args *ap)
   {
       cdev_t dev = ap->a_head.a_dev;
       struct twed_softc   *sc = (struct twed_softc *)dev->si_drv1;
   
       debug_called(4);
           
       if (sc == NULL)
           return (ENXIO);
   
       /* check that the controller is up and running */
       if (sc->twed_controller->twe_state & TWE_STATE_SHUTDOWN)
           return(ENXIO);
   
       sc->twed_flags |= TWED_OPEN;
       return (0);
   }
   
   /********************************************************************************
    * Handle last close of the disk device.
    */
   static int
   twed_close(struct dev_close_args *ap)
   {
       cdev_t dev = ap->a_head.a_dev;
       struct twed_softc   *sc = (struct twed_softc *)dev->si_drv1;
   
       debug_called(4);
           
       if (sc == NULL)
           return (ENXIO);
   
       sc->twed_flags &= ~TWED_OPEN;
       return (0);
   }
   
   /********************************************************************************
    * Handle an I/O request.
    */
   static int
   twed_strategy(struct dev_strategy_args *ap)
   {
       cdev_t dev = ap->a_head.a_dev;
       struct bio *bio = ap->a_bio;
       struct twed_softc *sc = dev->si_drv1;
       struct buf *bp = bio->bio_buf;
   
       bio->bio_driver_info = sc;
   
       debug_called(4);
   
       TWED_BIO_IN;
   
       /* bogus disk? */
       if (sc == NULL || sc->twed_drive->td_disk == NULL) {
           bp->b_error = EINVAL;
           bp->b_flags |= B_ERROR;
           kprintf("twe: bio for invalid disk!\n");
           biodone(bio);
           TWED_BIO_OUT;
           return(0);
       }
   
       /* perform accounting */
       devstat_start_transaction(&sc->twed_stats);
   
       /* queue the bio on the controller */
       TWE_IO_LOCK(sc->twed_controller);
       twe_enqueue_bio(sc->twed_controller, bio);
   
       /* poke the controller to start I/O */
       twe_startio(sc->twed_controller);
       TWE_IO_UNLOCK(sc->twed_controller);
       return(0);
   }
   
   /********************************************************************************
    * System crashdump support
    */
   static int
   twed_dump(struct dev_dump_args *ap)
   {
       cdev_t dev = ap->a_head.a_dev;
       size_t length = ap->a_length;
       off_t offset = ap->a_offset;
       void *virtual = ap->a_virtual;
       struct twed_softc   *twed_sc;
       struct twe_softc    *twe_sc;
       int                 error;
   
       twed_sc = dev->si_drv1;
       if (twed_sc == NULL)
           return(ENXIO);
       twe_sc  = (struct twe_softc *)twed_sc->twed_controller;
   
       if (length > 0) {
           if ((error = twe_dump_blocks(twe_sc, twed_sc->twed_drive->td_twe_unit, offset / TWE_BLOCK_SIZE, virtual, length / TWE_BLOCK_SIZE)) != 0)
               return(error);
       }
       return(0);
   }
   
   /********************************************************************************
    * Handle completion of an I/O request.
    */
   void
   twed_intr(struct bio *bio)
   {
       struct buf *bp = bio->bio_buf;
       struct twed_softc *sc = bio->bio_driver_info;
   
       debug_called(4);
   
       /* if no error, transfer completed */
       if (!(bp->b_flags & B_ERROR))
           bp->b_resid = 0;
       devstat_end_transaction_buf(&sc->twed_stats, bp);
       biodone(bio);
       TWED_BIO_OUT;
   }
   
   /********************************************************************************
    * Default probe stub.
    */
   static int
   twed_probe(device_t dev)
   {
       return (0);
   }
   
   /********************************************************************************
    * Attach a unit to the controller.
    */
   static int
   twed_attach(device_t dev)
   {
       struct twed_softc   *sc;
       struct disk_info    info;
       device_t            parent;
       cdev_t              dsk;
       
       debug_called(4);
   
       /* initialise our softc */
       sc = device_get_softc(dev);
       parent = device_get_parent(dev);
       sc->twed_controller = (struct twe_softc *)device_get_softc(parent);
       sc->twed_drive = device_get_ivars(dev);
       sc->twed_dev = dev;
   
       /* report the drive */
       twed_printf(sc, "%uMB (%u sectors)\n",
                   sc->twed_drive->td_size / ((1024 * 1024) / TWE_BLOCK_SIZE),
                   sc->twed_drive->td_size);
       
       /* attach a generic disk device to ourselves */
   
       sc->twed_drive->td_sys_unit = device_get_unit(dev);
   
       devstat_add_entry(&sc->twed_stats, "twed", sc->twed_drive->td_sys_unit,
                           TWE_BLOCK_SIZE,
                           DEVSTAT_NO_ORDERED_TAGS,
                           DEVSTAT_TYPE_STORARRAY | DEVSTAT_TYPE_IF_OTHER, 
                           DEVSTAT_PRIORITY_ARRAY);
   
       dsk = disk_create(sc->twed_drive->td_sys_unit, &sc->twed_disk, &twed_ops);
       dsk->si_drv1 = sc;
       sc->twed_dev_t = dsk;
   
       /* set the maximum I/O size to the theoretical maximum allowed by the S/G list size */
       dsk->si_iosize_max = (TWE_MAX_SGL_LENGTH - 1) * PAGE_SIZE;
   
       /*
        * Set disk info, as it appears that all needed data is available already.
        * Setting the disk info will also cause the probing to start.
        */
       bzero(&info, sizeof(info));
       info.d_media_blksize    = TWE_BLOCK_SIZE;   /* mandatory */
       info.d_media_blocks     = sc->twed_drive->td_size;
   
       info.d_type         = DTYPE_ESDI;           /* optional */
       info.d_secpertrack  = sc->twed_drive->td_sectors;
       info.d_nheads       = sc->twed_drive->td_heads;
       info.d_ncylinders   = sc->twed_drive->td_cylinders;
       info.d_secpercyl    = sc->twed_drive->td_sectors * sc->twed_drive->td_heads;
   
       disk_setdiskinfo(&sc->twed_disk, &info);
   
       return (0);
   }
   
   /********************************************************************************
    * Disconnect ourselves from the system.
    */
   static int
   twed_detach(device_t dev)
   {
       struct twed_softc *sc = (struct twed_softc *)device_get_softc(dev);
   
       debug_called(4);
   
       if (sc->twed_flags & TWED_OPEN)
           return(EBUSY);
   
       devstat_remove_entry(&sc->twed_stats);
       disk_destroy(&sc->twed_disk);
   
       return(0);
   }
   
   /********************************************************************************
    ********************************************************************************
                                                                                Misc
    ********************************************************************************
    ********************************************************************************/
   
   /********************************************************************************
    * Allocate a command buffer
    */
   static MALLOC_DEFINE(TWE_MALLOC_CLASS, "twe_commands", "twe commands");
   
   struct twe_request *
   twe_allocate_request(struct twe_softc *sc, int tag)
   {
       struct twe_request  *tr;
       int aligned_size;
   
       /*
        * TWE requires requests to be 512-byte aligned.  Depend on malloc()
        * guarenteeing alignment for power-of-2 requests.  Note that the old
        * (FreeBSD-4.x) malloc code aligned all requests, but the new slab
        * allocator only guarentees same-size alignment for power-of-2 requests.
        */
       aligned_size = (sizeof(struct twe_request) + TWE_ALIGNMASK) &
           ~TWE_ALIGNMASK;
       tr = kmalloc(aligned_size, TWE_MALLOC_CLASS, M_INTWAIT | M_ZERO);
       tr->tr_sc = sc;
       tr->tr_tag = tag;
       if (bus_dmamap_create(sc->twe_buffer_dmat, 0, &tr->tr_dmamap)) {
           twe_free_request(tr);
           twe_printf(sc, "unable to allocate dmamap for tag %d\n", tag);
           return(NULL);
       }    
       return(tr);
   }
   
   /********************************************************************************
    * Permanently discard a command buffer.
    */
   void
   twe_free_request(struct twe_request *tr) 
   {
       struct twe_softc    *sc = tr->tr_sc;
       
       debug_called(4);
   
       bus_dmamap_destroy(sc->twe_buffer_dmat, tr->tr_dmamap);
       kfree(tr, TWE_MALLOC_CLASS);
   }
   
   /********************************************************************************
    * Map/unmap (tr)'s command and data in the controller's addressable space.
    *
    * These routines ensure that the data which the controller is going to try to
    * access is actually visible to the controller, in a machine-independant 
    * fashion.  Due to a hardware limitation, I/O buffers must be 512-byte aligned
    * and we take care of that here as well.
    */
   static void
   twe_fillin_sgl(TWE_SG_Entry *sgl, bus_dma_segment_t *segs, int nsegments, int max_sgl)
   {
       int i;
   
       for (i = 0; i < nsegments; i++) {
           sgl[i].address = segs[i].ds_addr;
           sgl[i].length = segs[i].ds_len;
       }
       for (; i < max_sgl; i++) {                          /* XXX necessary? */
           sgl[i].address = 0;
           sgl[i].length = 0;
       }
   }
                   
   static void
   twe_setup_data_dmamap(void *arg, bus_dma_segment_t *segs, int nsegments, int error)
   {
       struct twe_request  *tr = (struct twe_request *)arg;
       struct twe_softc    *sc = tr->tr_sc;
       TWE_Command         *cmd = TWE_FIND_COMMAND(tr);
   
       debug_called(4);
   
       if (tr->tr_flags & TWE_CMD_MAPPED)
           panic("already mapped command");
   
       tr->tr_flags |= TWE_CMD_MAPPED;
  
      if (tr->tr_flags & TWE_CMD_IN_PROGRESS)
          sc->twe_state &= ~TWE_STATE_FRZN;
      /* save base of first segment in command (applicable if there only one segment) */
      tr->tr_dataphys = segs[0].ds_addr;
  
      /* correct command size for s/g list size */
      cmd->generic.size += 2 * nsegments;
  
      /*
       * Due to the fact that parameter and I/O commands have the scatter/gather list in
       * different places, we need to determine which sort of command this actually is
       * before we can populate it correctly.
       */
      switch(cmd->generic.opcode) {
      case TWE_OP_GET_PARAM:
      case TWE_OP_SET_PARAM:
          cmd->generic.sgl_offset = 2;
          twe_fillin_sgl(&cmd->param.sgl[0], segs, nsegments, TWE_MAX_SGL_LENGTH);
          break;
      case TWE_OP_READ:
      case TWE_OP_WRITE:
          cmd->generic.sgl_offset = 3;
          twe_fillin_sgl(&cmd->io.sgl[0], segs, nsegments, TWE_MAX_SGL_LENGTH);
          break;
      case TWE_OP_ATA_PASSTHROUGH:
          cmd->generic.sgl_offset = 5;
          twe_fillin_sgl(&cmd->ata.sgl[0], segs, nsegments, TWE_MAX_ATA_SGL_LENGTH);
          break;
      default:
          /*
           * Fall back to what the linux driver does.
           * Do this because the API may send an opcode
           * the driver knows nothing about and this will
           * at least stop PCIABRT's from hosing us.
           */
          switch (cmd->generic.sgl_offset) {
          case 2:
              twe_fillin_sgl(&cmd->param.sgl[0], segs, nsegments, TWE_MAX_SGL_LENGTH);
              break;
          case 3:
              twe_fillin_sgl(&cmd->io.sgl[0], segs, nsegments, TWE_MAX_SGL_LENGTH);
              break;
          case 5:
              twe_fillin_sgl(&cmd->ata.sgl[0], segs, nsegments, TWE_MAX_ATA_SGL_LENGTH);
              break;
          }
      }
  
      if (tr->tr_flags & TWE_CMD_DATAIN) {
          if (tr->tr_flags & TWE_CMD_IMMEDIATE) {
              bus_dmamap_sync(sc->twe_immediate_dmat, sc->twe_immediate_map,
                              BUS_DMASYNC_PREREAD);
          } else {
              bus_dmamap_sync(sc->twe_buffer_dmat, tr->tr_dmamap,
                              BUS_DMASYNC_PREREAD);
          }
      }
  
      if (tr->tr_flags & TWE_CMD_DATAOUT) {
          /*
           * if we're using an alignment buffer, and we're writing data
           * copy the real data out
           */
          if (tr->tr_flags & TWE_CMD_ALIGNBUF)
              bcopy(tr->tr_realdata, tr->tr_data, tr->tr_length);
  
          if (tr->tr_flags & TWE_CMD_IMMEDIATE) {
              bus_dmamap_sync(sc->twe_immediate_dmat, sc->twe_immediate_map,
                              BUS_DMASYNC_PREWRITE);
          } else {
              bus_dmamap_sync(sc->twe_buffer_dmat, tr->tr_dmamap,
                              BUS_DMASYNC_PREWRITE);
          }
      }
  
      if (twe_start(tr) == EBUSY) {
          tr->tr_sc->twe_state |= TWE_STATE_CTLR_BUSY;
          twe_requeue_ready(tr);
      }
  }
  
  static void
  twe_setup_request_dmamap(void *arg, bus_dma_segment_t *segs, int nsegments, int error)
  {
      struct twe_softc    *sc = (struct twe_softc *)arg;
  
      debug_called(4);
  
      /* command can't cross a page boundary */
      sc->twe_cmdphys = segs[0].ds_addr;
  }
  
  int
  twe_map_request(struct twe_request *tr)
  {
      struct twe_softc    *sc = tr->tr_sc;
      int                 error = 0;
  
      debug_called(4);
  
      twe_lockassert(&sc->twe_io_lock);
      if (sc->twe_state & (TWE_STATE_CTLR_BUSY | TWE_STATE_FRZN)) {
          twe_requeue_ready(tr);
          return (EBUSY);
      }
  
      bus_dmamap_sync(sc->twe_cmd_dmat, sc->twe_cmdmap, BUS_DMASYNC_PREWRITE);
  
      /*
       * If the command involves data, map that too.
       */
      if (tr->tr_data != NULL && ((tr->tr_flags & TWE_CMD_MAPPED) == 0)) {
  
          /* 
           * Data must be 512-byte aligned; allocate a fixup buffer if it's not.
           *
           * DragonFly's malloc only guarentees alignment for requests which
           * are power-of-2 sized.
           */
          if (((vm_offset_t)tr->tr_data % TWE_ALIGNMENT) != 0) {
              int aligned_size;
  
              tr->tr_realdata = tr->tr_data;      /* save pointer to 'real' data */
              aligned_size = TWE_ALIGNMENT;
              while (aligned_size < tr->tr_length)
                  aligned_size <<= 1;
              tr->tr_flags |= TWE_CMD_ALIGNBUF;
              tr->tr_data = kmalloc(aligned_size, TWE_MALLOC_CLASS, M_INTWAIT);
              if (tr->tr_data == NULL) {
                  twe_printf(sc, "%s: malloc failed\n", __func__);
                  tr->tr_data = tr->tr_realdata; /* restore original data pointer */
                  return(ENOMEM);
              }
          }
          
          /*
           * Map the data buffer into bus space and build the s/g list.
           */
          if (tr->tr_flags & TWE_CMD_IMMEDIATE) {
              error = bus_dmamap_load(sc->twe_immediate_dmat, sc->twe_immediate_map, sc->twe_immediate,
                              tr->tr_length, twe_setup_data_dmamap, tr, BUS_DMA_NOWAIT);
          } else {
              error = bus_dmamap_load(sc->twe_buffer_dmat, tr->tr_dmamap, tr->tr_data, tr->tr_length,
                                      twe_setup_data_dmamap, tr, 0);
          }
          if (error == EINPROGRESS) {
              tr->tr_flags |= TWE_CMD_IN_PROGRESS;
              sc->twe_state |= TWE_STATE_FRZN;
              error = 0;
          }
      } else
          if ((error = twe_start(tr)) == EBUSY) {
              sc->twe_state |= TWE_STATE_CTLR_BUSY;
              twe_requeue_ready(tr);
          }
  
      return(error);
  }
  
  void
  twe_unmap_request(struct twe_request *tr)
  {
      struct twe_softc    *sc = tr->tr_sc;
  
      debug_called(4);
  
      bus_dmamap_sync(sc->twe_cmd_dmat, sc->twe_cmdmap, BUS_DMASYNC_POSTWRITE);
  
      /*
       * If the command involved data, unmap that too.
       */
      if (tr->tr_data != NULL) {
          if (tr->tr_flags & TWE_CMD_DATAIN) {
              if (tr->tr_flags & TWE_CMD_IMMEDIATE) {
                  bus_dmamap_sync(sc->twe_immediate_dmat, sc->twe_immediate_map,
                                  BUS_DMASYNC_POSTREAD);
              } else {
                  bus_dmamap_sync(sc->twe_buffer_dmat, tr->tr_dmamap,
                                  BUS_DMASYNC_POSTREAD);
              }
  
              /* if we're using an alignment buffer, and we're reading data, copy the real data in */
              if (tr->tr_flags & TWE_CMD_ALIGNBUF)
                  bcopy(tr->tr_data, tr->tr_realdata, tr->tr_length);
          }
          if (tr->tr_flags & TWE_CMD_DATAOUT) {
              if (tr->tr_flags & TWE_CMD_IMMEDIATE) {
                  bus_dmamap_sync(sc->twe_immediate_dmat, sc->twe_immediate_map,
                                  BUS_DMASYNC_POSTWRITE);
              } else {
                  bus_dmamap_sync(sc->twe_buffer_dmat, tr->tr_dmamap,
                                  BUS_DMASYNC_POSTWRITE);
              }
          }
  
          if (tr->tr_flags & TWE_CMD_IMMEDIATE) {
              bus_dmamap_unload(sc->twe_immediate_dmat, sc->twe_immediate_map);
          } else {
              bus_dmamap_unload(sc->twe_buffer_dmat, tr->tr_dmamap);
          }
      }
  
      /* free alignment buffer if it was used */
      if (tr->tr_flags & TWE_CMD_ALIGNBUF) {
          kfree(tr->tr_data, TWE_MALLOC_CLASS);
          tr->tr_data = tr->tr_realdata;          /* restore 'real' data pointer */
      }
  }
  
  #ifdef TWE_DEBUG
  void twe_report(void);
  /********************************************************************************
   * Print current controller status, call from DDB.
   */
  void
  twe_report(void)
  {
      struct twe_softc    *sc;
      int                 i;
  
      for (i = 0; (sc = devclass_get_softc(twe_devclass, i)) != NULL; i++)
          twe_print_controller(sc);
      kprintf("twed: total bio count in %u  out %u\n", twed_bio_in, twed_bio_out);
  }
  #endif

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