FreeBSD/Linux Kernel Cross Reference
sys/dev/ata/ata-queue.c

     /*-
      * Copyright (c) 1998 - 2008 Søren Schmidt <sos@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,
     *    without modification, immediately at the beginning of the file.
     * 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 ``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 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.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/8.4/sys/dev/ata/ata-queue.c 233718 2012-03-30 23:56:19Z marius $");
    
    #include "opt_ata.h"
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/ata.h>
    #include <sys/kernel.h>
    #include <sys/bio.h>
    #include <sys/bus.h>
    #include <sys/conf.h>
    #include <sys/sema.h>
    #include <sys/taskqueue.h>
    #include <vm/uma.h>
    #include <machine/bus.h>
    #include <sys/rman.h>
    #include <dev/ata/ata-all.h>
    #include <ata_if.h>
    
    #ifndef ATA_CAM
    /* prototypes */
    static void ata_completed(void *, int);
    static void ata_sort_queue(struct ata_channel *ch, struct ata_request *request);
    static const char *ata_skey2str(u_int8_t);
    #endif
    
    #ifndef ATA_CAM
    void
    ata_queue_request(struct ata_request *request)
    {
        struct ata_channel *ch;
        struct ata_device *atadev = device_get_softc(request->dev);
    
        /* treat request as virgin (this might be an ATA_R_REQUEUE) */
        request->result = request->status = request->error = 0;
    
        /* Prepare paramers required by low-level code. */
        request->unit = atadev->unit;
        if (!(request->parent = device_get_parent(request->dev))) {
            request->result = ENXIO;
            if (request->callback)
                (request->callback)(request);
            return;
        }
        if ((atadev->param.config & ATA_PROTO_MASK) == ATA_PROTO_ATAPI_16)
            request->flags |= ATA_R_ATAPI16;
        if ((atadev->param.config & ATA_DRQ_MASK) == ATA_DRQ_INTR)
            request->flags |= ATA_R_ATAPI_INTR;
        if ((request->flags & ATA_R_ATAPI) == 0)
            ata_modify_if_48bit(request);
        ch = device_get_softc(request->parent);
        callout_init_mtx(&request->callout, &ch->state_mtx, CALLOUT_RETURNUNLOCKED);
        if (!request->callback && !(request->flags & ATA_R_REQUEUE))
            sema_init(&request->done, 0, "ATA request done");
    
        /* in ATA_STALL_QUEUE state we call HW directly */
        if ((ch->state & ATA_STALL_QUEUE) && (request->flags & ATA_R_CONTROL)) {
            mtx_lock(&ch->state_mtx);
            ch->running = request;
            if (ch->hw.begin_transaction(request) == ATA_OP_FINISHED) {
                ch->running = NULL;
                if (!request->callback) 
                    sema_destroy(&request->done);
                mtx_unlock(&ch->state_mtx);
                return;
            }
            mtx_unlock(&ch->state_mtx);
        }
        /* otherwise put request on the locked queue at the specified location */
        else  {
            mtx_lock(&ch->queue_mtx);
            if (request->flags & ATA_R_AT_HEAD)
                TAILQ_INSERT_HEAD(&ch->ata_queue, request, chain);
           else if (request->flags & ATA_R_ORDERED)
               ata_sort_queue(ch, request);
           else
               TAILQ_INSERT_TAIL(&ch->ata_queue, request, chain);
           mtx_unlock(&ch->queue_mtx);
           ATA_DEBUG_RQ(request, "queued");
           ata_start(ch->dev);
       }
   
       /* if this is a requeued request callback/sleep we're done */
       if (request->flags & ATA_R_REQUEUE)
           return;
   
       /* if this is not a callback wait until request is completed */
       if (!request->callback) {
           ATA_DEBUG_RQ(request, "wait for completion");
           if (!dumping &&
               sema_timedwait(&request->done, request->timeout * hz * 4)) {
               callout_drain(&request->callout);
               device_printf(request->dev,
                             "WARNING - %s taskqueue timeout "
                             "- completing request directly\n",
                             ata_cmd2str(request));
               request->flags |= ATA_R_DANGER1;
               ata_completed(request, 0);
           }
           sema_destroy(&request->done);
       }
   }
   #endif
   
   #ifndef ATA_CAM
   int
   ata_controlcmd(device_t dev, u_int8_t command, u_int16_t feature,
                  u_int64_t lba, u_int16_t count)
   {
       struct ata_device *atadev = device_get_softc(dev);
       struct ata_request *request = ata_alloc_request();
       int error = ENOMEM;
   
       if (request) {
           request->dev = dev;
           request->u.ata.command = command;
           request->u.ata.lba = lba;
           request->u.ata.count = count;
           request->u.ata.feature = feature;
           request->flags = ATA_R_CONTROL;
           if (atadev->spindown_state) {
               device_printf(dev, "request while spun down, starting.\n");
               atadev->spindown_state = 0;
               request->timeout = MAX(ATA_REQUEST_TIMEOUT, 31);
           } else {
               request->timeout = ATA_REQUEST_TIMEOUT;
           }
           request->retries = 0;
           ata_queue_request(request);
           error = request->result;
           ata_free_request(request);
       }
       return error;
   }
   #endif
   
   #ifndef ATA_CAM
   int
   ata_atapicmd(device_t dev, u_int8_t *ccb, caddr_t data,
                int count, int flags, int timeout)
   {
       struct ata_request *request = ata_alloc_request();
       int error = ENOMEM;
   
       if (request) {
           request->dev = dev;
           bcopy(ccb, request->u.atapi.ccb, 16);
           request->data = data;
           request->bytecount = count;
           request->transfersize = min(request->bytecount, 65534);
           request->flags = flags | ATA_R_ATAPI;
           request->timeout = timeout;
           request->retries = 0;
           ata_queue_request(request);
           error = request->result;
           ata_free_request(request);
       }
       return error;
   }
   #endif
   
   #ifndef ATA_CAM
   void
   ata_start(device_t dev)
   {
       struct ata_channel *ch = device_get_softc(dev);
       struct ata_request *request;
       struct ata_composite *cptr;
       int dependencies = 0;
   
       /* if we have a request on the queue try to get it running */
       mtx_lock(&ch->queue_mtx);
       if ((request = TAILQ_FIRST(&ch->ata_queue))) {
   
           /* we need the locking function to get the lock for this channel */
           if (ATA_LOCKING(dev, ATA_LF_LOCK) == ch->unit) {
   
               /* check for composite dependencies */
               if ((cptr = request->composite)) {
                   mtx_lock(&cptr->lock);
                   if ((request->flags & ATA_R_WRITE) &&
                       (cptr->wr_depend & cptr->rd_done) != cptr->wr_depend) {
                       dependencies = 1;
                   }
                   mtx_unlock(&cptr->lock);
               }
   
               /* check we are in the right state and has no dependencies */
               mtx_lock(&ch->state_mtx);
               if (ch->state == ATA_IDLE && !dependencies) {
                   ATA_DEBUG_RQ(request, "starting");
                   TAILQ_REMOVE(&ch->ata_queue, request, chain);
                   ch->running = request;
                   ch->state = ATA_ACTIVE;
   
                   /* if we are the freezing point release it */
                   if (ch->freezepoint == request)
                       ch->freezepoint = NULL;
   
                   if (ch->hw.begin_transaction(request) == ATA_OP_FINISHED) {
                       ch->running = NULL;
                       ch->state = ATA_IDLE;
                       mtx_unlock(&ch->state_mtx);
                       mtx_unlock(&ch->queue_mtx);
                       ATA_LOCKING(dev, ATA_LF_UNLOCK);
                       ata_finish(request);
                       return;
                   }
               }
               mtx_unlock(&ch->state_mtx);
           }
       }
       mtx_unlock(&ch->queue_mtx);
       if (dumping) {
           while (ch->running) {
               ata_interrupt(ch);
               DELAY(10);
           }
       }
   }
   #endif
   
   #ifndef ATA_CAM
   void
   ata_finish(struct ata_request *request)
   {
       struct ata_channel *ch = device_get_softc(request->parent);
   
       /*
        * if in ATA_STALL_QUEUE state or request has ATA_R_DIRECT flags set
        * we need to call ata_complete() directly here (no taskqueue involvement)
        */
       if (dumping ||
           (ch->state & ATA_STALL_QUEUE) || (request->flags & ATA_R_DIRECT)) {
           ATA_DEBUG_RQ(request, "finish directly");
           ata_completed(request, 0);
       }
       else {
           /* put request on the proper taskqueue for completion */
           if (request->bio && !(request->flags & (ATA_R_THREAD | ATA_R_TIMEOUT))){
               ATA_DEBUG_RQ(request, "finish bio_taskqueue");
               bio_taskqueue(request->bio, (bio_task_t *)ata_completed, request);
           }
           else {
               TASK_INIT(&request->task, 0, ata_completed, request);
               ATA_DEBUG_RQ(request, "finish taskqueue_swi");
               taskqueue_enqueue(taskqueue_swi, &request->task);
           }
       }
   }
   #endif
   
   #ifndef ATA_CAM
   static void
   ata_completed(void *context, int dummy)
   {
       struct ata_request *request = (struct ata_request *)context;
       struct ata_channel *ch = device_get_softc(request->parent);
       struct ata_device *atadev = device_get_softc(request->dev);
       struct ata_composite *composite;
   
       if (request->flags & ATA_R_DANGER2) {
           device_printf(request->dev,
                         "WARNING - %s freeing taskqueue zombie request\n",
                         ata_cmd2str(request));
           request->flags &= ~(ATA_R_DANGER1 | ATA_R_DANGER2);
           ata_free_request(request);
           return;
       }
       if (request->flags & ATA_R_DANGER1)
           request->flags |= ATA_R_DANGER2;
   
       ATA_DEBUG_RQ(request, "completed entered");
   
       /* if we had a timeout, reinit channel and deal with the falldown */
       if (request->flags & ATA_R_TIMEOUT) {
           /*
            * if the channel is still present and
            * reinit succeeds and
            * the device doesn't get detached and
            * there are retries left we reinject this request
            */
           if (ch && !ata_reinit(ch->dev) && !request->result &&
               (request->retries-- > 0)) {
               if (!(request->flags & ATA_R_QUIET)) {
                   device_printf(request->dev,
                                 "TIMEOUT - %s retrying (%d retr%s left)",
                                 ata_cmd2str(request), request->retries,
                                 request->retries == 1 ? "y" : "ies");
                   if (!(request->flags & (ATA_R_ATAPI | ATA_R_CONTROL)))
                       printf(" LBA=%ju", request->u.ata.lba);
                   printf("\n");
               }
               request->flags &= ~(ATA_R_TIMEOUT | ATA_R_DEBUG);
               request->flags |= (ATA_R_AT_HEAD | ATA_R_REQUEUE);
               ATA_DEBUG_RQ(request, "completed reinject");
               ata_queue_request(request);
               return;
           }
   
           /* ran out of good intentions so finish with error */
           if (!request->result) {
               if (!(request->flags & ATA_R_QUIET)) {
                   if (request->dev) {
                       device_printf(request->dev, "FAILURE - %s timed out",
                                     ata_cmd2str(request));
                       if (!(request->flags & (ATA_R_ATAPI | ATA_R_CONTROL)))
                           printf(" LBA=%ju", request->u.ata.lba);
                       printf("\n");
                   }
               }
               request->result = EIO;
           }
       }
       else if (!(request->flags & ATA_R_ATAPI) ){
           /* if this is a soft ECC error warn about it */
           /* XXX SOS we could do WARF here */
           if ((request->status & (ATA_S_CORR | ATA_S_ERROR)) == ATA_S_CORR) {
               device_printf(request->dev,
                             "WARNING - %s soft error (ECC corrected)",
                             ata_cmd2str(request));
               if (!(request->flags & (ATA_R_ATAPI | ATA_R_CONTROL)))
                   printf(" LBA=%ju", request->u.ata.lba);
               printf("\n");
           }
   
           /* if this is a UDMA CRC error we reinject if there are retries left */
           if (request->flags & ATA_R_DMA && request->error & ATA_E_ICRC) {
               if (request->retries-- > 0) {
                   device_printf(request->dev,
                                 "WARNING - %s UDMA ICRC error (retrying request)",
                                 ata_cmd2str(request));
                   if (!(request->flags & (ATA_R_ATAPI | ATA_R_CONTROL)))
                       printf(" LBA=%ju", request->u.ata.lba);
                   printf("\n");
                   request->flags |= (ATA_R_AT_HEAD | ATA_R_REQUEUE);
                   ata_queue_request(request);
                   return;
               }
           }
       }
   
       switch (request->flags & ATA_R_ATAPI) {
   
       /* ATA errors */
       default:
           if (!request->result && request->status & ATA_S_ERROR) {
               if (!(request->flags & ATA_R_QUIET)) {
                   device_printf(request->dev,
                                 "FAILURE - %s status=%b error=%b", 
                                 ata_cmd2str(request),
                                 request->status, "\2\10BUSY\7READY\6DMA_READY"
                                 "\5DSC\4DRQ\3CORRECTABLE\2INDEX\1ERROR",
                                 request->error, "\2\10ICRC\7UNCORRECTABLE"
                                 "\6MEDIA_CHANGED\5NID_NOT_FOUND"
                                 "\4MEDIA_CHANGE_REQEST"
                                 "\3ABORTED\2NO_MEDIA\1ILLEGAL_LENGTH");
                   if ((request->flags & ATA_R_DMA) && request->dma &&
                       (request->dma->status & ATA_BMSTAT_ERROR))
                       printf(" dma=0x%02x", request->dma->status);
                   if (!(request->flags & (ATA_R_ATAPI | ATA_R_CONTROL)))
                       printf(" LBA=%ju", request->u.ata.lba);
                   printf("\n");
               }
               request->result = EIO;
           }
           break;
   
       /* ATAPI errors */
       case ATA_R_ATAPI:
           /* skip if result already set */
           if (request->result)
               break;
   
           /* if we have a sensekey -> request sense from device */
           if ((request->error & ATA_E_ATAPI_SENSE_MASK) &&
               (request->u.atapi.ccb[0] != ATAPI_REQUEST_SENSE)) {
               static u_int8_t ccb[16] = { ATAPI_REQUEST_SENSE, 0, 0, 0,
                                           sizeof(struct atapi_sense),
                                           0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
   
               request->u.atapi.saved_cmd = request->u.atapi.ccb[0];
               bcopy(ccb, request->u.atapi.ccb, 16);
               request->data = (caddr_t)&request->u.atapi.sense;
               request->bytecount = sizeof(struct atapi_sense);
               request->donecount = 0;
               request->transfersize = sizeof(struct atapi_sense);
               request->timeout = ATA_REQUEST_TIMEOUT;
               request->flags &= (ATA_R_ATAPI | ATA_R_QUIET | ATA_R_DEBUG);
               request->flags |= (ATA_R_READ | ATA_R_AT_HEAD | ATA_R_REQUEUE);
               ATA_DEBUG_RQ(request, "autoissue request sense");
               ata_queue_request(request);
               return;
           }
   
           switch (request->u.atapi.sense.key & ATA_SENSE_KEY_MASK) {
           case ATA_SENSE_RECOVERED_ERROR:
               device_printf(request->dev, "WARNING - %s recovered error\n",
                             ata_cmd2str(request));
               /* FALLTHROUGH */
   
           case ATA_SENSE_NO_SENSE:
               request->result = 0;
               break;
   
           case ATA_SENSE_NOT_READY: 
               request->result = EBUSY;
               break;
   
           case ATA_SENSE_UNIT_ATTENTION:
               atadev->flags |= ATA_D_MEDIA_CHANGED;
               request->result = EIO;
               break;
   
           default:
               request->result = EIO;
               if (request->flags & ATA_R_QUIET)
                   break;
   
               device_printf(request->dev,
                             "FAILURE - %s %s asc=0x%02x ascq=0x%02x ",
                             ata_cmd2str(request), ata_skey2str(
                             (request->u.atapi.sense.key & ATA_SENSE_KEY_MASK)),
                             request->u.atapi.sense.asc,
                             request->u.atapi.sense.ascq);
               if (request->u.atapi.sense.specific & ATA_SENSE_SPEC_VALID)
                   printf("sks=0x%02x 0x%02x 0x%02x\n",
                          request->u.atapi.sense.specific & ATA_SENSE_SPEC_MASK,
                          request->u.atapi.sense.specific1,
                          request->u.atapi.sense.specific2);
               else
                   printf("\n");
           }
   
           if (!request->result &&
                (request->u.atapi.sense.key & ATA_SENSE_KEY_MASK ||
                request->error))
               request->result = EIO;
       }
   
       ATA_DEBUG_RQ(request, "completed callback/wakeup");
   
       /* if we are part of a composite operation we need to maintain progress */
       if ((composite = request->composite)) {
           int index = 0;
   
           mtx_lock(&composite->lock);
   
           /* update whats done */
           if (request->flags & ATA_R_READ)
               composite->rd_done |= (1 << request->this);
           if (request->flags & ATA_R_WRITE)
               composite->wr_done |= (1 << request->this);
   
           /* find ready to go dependencies */
           if (composite->wr_depend &&
               (composite->rd_done & composite->wr_depend)==composite->wr_depend &&
               (composite->wr_needed & (~composite->wr_done))) {
               index = composite->wr_needed & ~composite->wr_done;
           }
   
           mtx_unlock(&composite->lock);
   
           /* if we have any ready candidates kick them off */
           if (index) {
               int bit;
               
               for (bit = 0; bit < MAX_COMPOSITES; bit++) {
                   if (index & (1 << bit))
                       ata_start(device_get_parent(composite->request[bit]->dev));
               }
           }
       }
   
       /* get results back to the initiator for this request */
       if (request->callback)
           (request->callback)(request);
       else
           sema_post(&request->done);
   
       /* only call ata_start if channel is present */
       if (ch)
           ata_start(ch->dev);
   }
   #endif
   
   void
   ata_timeout(struct ata_request *request)
   {
       struct ata_channel *ch = device_get_softc(request->parent);
   
       //request->flags |= ATA_R_DEBUG;
       ATA_DEBUG_RQ(request, "timeout");
   
       /*
        * if we have an ATA_ACTIVE request running, we flag the request 
        * ATA_R_TIMEOUT so ata_finish will handle it correctly
        * also NULL out the running request so we wont loose 
        * the race with an eventual interrupt arriving late
        */
       if (ch->state == ATA_ACTIVE) {
           request->flags |= ATA_R_TIMEOUT;
           if (ch->dma.unload)
               ch->dma.unload(request);
           ch->running = NULL;
           ch->state = ATA_IDLE;
   #ifdef ATA_CAM
           ata_cam_end_transaction(ch->dev, request);
   #endif
           mtx_unlock(&ch->state_mtx);
   #ifndef ATA_CAM
           ATA_LOCKING(ch->dev, ATA_LF_UNLOCK);
           ata_finish(request);
   #endif
       }
       else {
           mtx_unlock(&ch->state_mtx);
       }
   }
   
   #ifndef ATA_CAM
   void
   ata_fail_requests(device_t dev)
   {
       struct ata_channel *ch = device_get_softc(device_get_parent(dev));
       struct ata_request *request, *tmp;
       TAILQ_HEAD(, ata_request) fail_requests;
       TAILQ_INIT(&fail_requests);
   
       /* grap all channel locks to avoid races */
       mtx_lock(&ch->queue_mtx);
       mtx_lock(&ch->state_mtx);
   
       /* do we have any running request to care about ? */
       if ((request = ch->running) && (!dev || request->dev == dev)) {
           callout_stop(&request->callout);
           ch->running = NULL;
           request->result = ENXIO;
           TAILQ_INSERT_TAIL(&fail_requests, request, chain);
       }
   
       /* fail all requests queued on this channel for device dev if !NULL */
       TAILQ_FOREACH_SAFE(request, &ch->ata_queue, chain, tmp) {
           if (!dev || request->dev == dev) {
               TAILQ_REMOVE(&ch->ata_queue, request, chain);
               request->result = ENXIO;
               TAILQ_INSERT_TAIL(&fail_requests, request, chain);
           }
       }
   
       mtx_unlock(&ch->state_mtx);
       mtx_unlock(&ch->queue_mtx);
      
       /* finish up all requests collected above */
       TAILQ_FOREACH_SAFE(request, &fail_requests, chain, tmp) {
           TAILQ_REMOVE(&fail_requests, request, chain);
           ata_finish(request);
       }
   }
   #endif
   
   #ifndef ATA_CAM
   /*
    * Rudely drop all requests queued to the channel of specified device.
    * XXX: The requests are leaked, use only in fatal case.
    */
   void
   ata_drop_requests(device_t dev)
   {
       struct ata_channel *ch = device_get_softc(device_get_parent(dev));
       struct ata_request *request, *tmp;
   
       mtx_lock(&ch->queue_mtx);
       TAILQ_FOREACH_SAFE(request, &ch->ata_queue, chain, tmp) {
           TAILQ_REMOVE(&ch->ata_queue, request, chain);
           request->result = ENXIO;
       }
       mtx_unlock(&ch->queue_mtx);
   }
   #endif
   
   #ifndef ATA_CAM
   static u_int64_t
   ata_get_lba(struct ata_request *request)
   {
       if (request->flags & ATA_R_ATAPI) {
           switch (request->u.atapi.ccb[0]) {
           case ATAPI_READ_BIG:
           case ATAPI_WRITE_BIG:
           case ATAPI_READ_CD:
               return (request->u.atapi.ccb[5]) | (request->u.atapi.ccb[4]<<8) |
                      (request->u.atapi.ccb[3]<<16)|(request->u.atapi.ccb[2]<<24);
           case ATAPI_READ:
           case ATAPI_WRITE:
               return (request->u.atapi.ccb[4]) | (request->u.atapi.ccb[3]<<8) |
                      (request->u.atapi.ccb[2]<<16);
           default:
               return 0;
           }
       }
       else
           return request->u.ata.lba;
   }
   #endif
   
   #ifndef ATA_CAM
   static void
   ata_sort_queue(struct ata_channel *ch, struct ata_request *request)
   {
       struct ata_request *this, *next;
   
       this = TAILQ_FIRST(&ch->ata_queue);
   
       /* if the queue is empty just insert */
       if (!this) {
           if (request->composite)
               ch->freezepoint = request;
           TAILQ_INSERT_TAIL(&ch->ata_queue, request, chain);
           return;
       }
   
       /* dont sort frozen parts of the queue */
       if (ch->freezepoint)
           this = ch->freezepoint;
           
       /* if position is less than head we add after tipping point */
       if (ata_get_lba(request) < ata_get_lba(this)) {
           while ((next = TAILQ_NEXT(this, chain))) {
   
               /* have we reached the tipping point */
               if (ata_get_lba(next) < ata_get_lba(this)) {
   
                   /* sort the insert */
                   do {
                       if (ata_get_lba(request) < ata_get_lba(next))
                           break;
                       this = next;
                   } while ((next = TAILQ_NEXT(this, chain)));
                   break;
               }
               this = next;
           }
       }
   
       /* we are after head so sort the insert before tipping point */
       else {
           while ((next = TAILQ_NEXT(this, chain))) {
               if (ata_get_lba(next) < ata_get_lba(this) ||
                   ata_get_lba(request) < ata_get_lba(next))
                   break;
               this = next;
           }
       }
   
       if (request->composite)
           ch->freezepoint = request;
       TAILQ_INSERT_AFTER(&ch->ata_queue, this, request, chain);
   }
   #endif
   
   const char *
   ata_cmd2str(struct ata_request *request)
   {
       static char buffer[20];
   
       if (request->flags & ATA_R_ATAPI) {
           switch (request->u.atapi.sense.key ?
                   request->u.atapi.saved_cmd : request->u.atapi.ccb[0]) {
           case 0x00: return ("TEST_UNIT_READY");
           case 0x01: return ("REZERO");
           case 0x03: return ("REQUEST_SENSE");
           case 0x04: return ("FORMAT");
           case 0x08: return ("READ");
           case 0x0a: return ("WRITE");
           case 0x10: return ("WEOF");
           case 0x11: return ("SPACE");
           case 0x12: return ("INQUIRY");
           case 0x15: return ("MODE_SELECT");
           case 0x19: return ("ERASE");
           case 0x1a: return ("MODE_SENSE");
           case 0x1b: return ("START_STOP");
           case 0x1e: return ("PREVENT_ALLOW");
           case 0x23: return ("ATAPI_READ_FORMAT_CAPACITIES");
           case 0x25: return ("READ_CAPACITY");
           case 0x28: return ("READ_BIG");
           case 0x2a: return ("WRITE_BIG");
           case 0x2b: return ("LOCATE");
           case 0x34: return ("READ_POSITION");
           case 0x35: return ("SYNCHRONIZE_CACHE");
           case 0x3b: return ("WRITE_BUFFER");
           case 0x3c: return ("READ_BUFFER");
           case 0x42: return ("READ_SUBCHANNEL");
           case 0x43: return ("READ_TOC");
           case 0x45: return ("PLAY_10");
           case 0x47: return ("PLAY_MSF");
           case 0x48: return ("PLAY_TRACK");
           case 0x4b: return ("PAUSE");
           case 0x51: return ("READ_DISK_INFO");
           case 0x52: return ("READ_TRACK_INFO");
           case 0x53: return ("RESERVE_TRACK");
           case 0x54: return ("SEND_OPC_INFO");
           case 0x55: return ("MODE_SELECT_BIG");
           case 0x58: return ("REPAIR_TRACK");
           case 0x59: return ("READ_MASTER_CUE");
           case 0x5a: return ("MODE_SENSE_BIG");
           case 0x5b: return ("CLOSE_TRACK/SESSION");
           case 0x5c: return ("READ_BUFFER_CAPACITY");
           case 0x5d: return ("SEND_CUE_SHEET");
           case 0x96: return ("SERVICE_ACTION_IN");
           case 0xa1: return ("BLANK_CMD");
           case 0xa3: return ("SEND_KEY");
           case 0xa4: return ("REPORT_KEY");
           case 0xa5: return ("PLAY_12");
           case 0xa6: return ("LOAD_UNLOAD");
           case 0xad: return ("READ_DVD_STRUCTURE");
           case 0xb4: return ("PLAY_CD");
           case 0xbb: return ("SET_SPEED");
           case 0xbd: return ("MECH_STATUS");
           case 0xbe: return ("READ_CD");
           case 0xff: return ("POLL_DSC");
           }
       }
       else {
           switch (request->u.ata.command) {
           case 0x00: return ("NOP");
           case 0x08: return ("DEVICE_RESET");
           case 0x20: return ("READ");
           case 0x24: return ("READ48");
           case 0x25: return ("READ_DMA48");
           case 0x26: return ("READ_DMA_QUEUED48");
           case 0x27: return ("READ_NATIVE_MAX_ADDRESS48");
           case 0x29: return ("READ_MUL48");
           case 0x30: return ("WRITE");
           case 0x34: return ("WRITE48");
           case 0x35: return ("WRITE_DMA48");
           case 0x36: return ("WRITE_DMA_QUEUED48");
           case 0x37: return ("SET_MAX_ADDRESS48");
           case 0x39: return ("WRITE_MUL48");
           case 0x70: return ("SEEK");
           case 0xa0: return ("PACKET_CMD");
           case 0xa1: return ("ATAPI_IDENTIFY");
           case 0xa2: return ("SERVICE");
           case 0xb0: return ("SMART");
           case 0xc0: return ("CFA ERASE");
           case 0xc4: return ("READ_MUL");
           case 0xc5: return ("WRITE_MUL");
           case 0xc6: return ("SET_MULTI");
           case 0xc7: return ("READ_DMA_QUEUED");
           case 0xc8: return ("READ_DMA");
           case 0xca: return ("WRITE_DMA");
           case 0xcc: return ("WRITE_DMA_QUEUED");
           case 0xe6: return ("SLEEP");
           case 0xe7: return ("FLUSHCACHE");
           case 0xea: return ("FLUSHCACHE48");
           case 0xec: return ("ATA_IDENTIFY");
           case 0xef:
               switch (request->u.ata.feature) {
               case 0x03: return ("SETFEATURES SET TRANSFER MODE");
               case 0x02: return ("SETFEATURES ENABLE WCACHE");
               case 0x82: return ("SETFEATURES DISABLE WCACHE");
               case 0xaa: return ("SETFEATURES ENABLE RCACHE");
               case 0x55: return ("SETFEATURES DISABLE RCACHE");
               }
               sprintf(buffer, "SETFEATURES 0x%02x", request->u.ata.feature);
               return buffer;
           case 0xf5: return ("SECURITY_FREE_LOCK");
           case 0xf8: return ("READ_NATIVE_MAX_ADDRESS");
           case 0xf9: return ("SET_MAX_ADDRESS");
           }
       }
       sprintf(buffer, "unknown CMD (0x%02x)", request->u.ata.command);
       return buffer;
   }
   
   #ifndef ATA_CAM
   static const char *
   ata_skey2str(u_int8_t skey)
   {
       switch (skey) {
       case 0x00: return ("NO SENSE");
       case 0x01: return ("RECOVERED ERROR");
       case 0x02: return ("NOT READY");
       case 0x03: return ("MEDIUM ERROR");
       case 0x04: return ("HARDWARE ERROR");
       case 0x05: return ("ILLEGAL REQUEST");
       case 0x06: return ("UNIT ATTENTION");
       case 0x07: return ("DATA PROTECT");
       case 0x08: return ("BLANK CHECK");
       case 0x09: return ("VENDOR SPECIFIC");
       case 0x0a: return ("COPY ABORTED");
       case 0x0b: return ("ABORTED COMMAND");
       case 0x0c: return ("EQUAL");
       case 0x0d: return ("VOLUME OVERFLOW");
       case 0x0e: return ("MISCOMPARE");
       case 0x0f: return ("RESERVED");
       default: return("UNKNOWN");
       }
   }
   #endif

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