ide-atapi: start DMA after issuing a packet command
[safe/jmp/linux-2.6] / drivers / ide / ide-atapi.c
1 /*
2  * ATAPI support.
3  */
4
5 #include <linux/kernel.h>
6 #include <linux/cdrom.h>
7 #include <linux/delay.h>
8 #include <linux/ide.h>
9 #include <linux/scatterlist.h>
10
11 #include <scsi/scsi.h>
12
13 #ifdef DEBUG
14 #define debug_log(fmt, args...) \
15         printk(KERN_INFO "ide: " fmt, ## args)
16 #else
17 #define debug_log(fmt, args...) do {} while (0)
18 #endif
19
20 #define ATAPI_MIN_CDB_BYTES     12
21
22 static inline int dev_is_idecd(ide_drive_t *drive)
23 {
24         return drive->media == ide_cdrom || drive->media == ide_optical;
25 }
26
27 /*
28  * Check whether we can support a device,
29  * based on the ATAPI IDENTIFY command results.
30  */
31 int ide_check_atapi_device(ide_drive_t *drive, const char *s)
32 {
33         u16 *id = drive->id;
34         u8 gcw[2], protocol, device_type, removable, drq_type, packet_size;
35
36         *((u16 *)&gcw) = id[ATA_ID_CONFIG];
37
38         protocol    = (gcw[1] & 0xC0) >> 6;
39         device_type =  gcw[1] & 0x1F;
40         removable   = (gcw[0] & 0x80) >> 7;
41         drq_type    = (gcw[0] & 0x60) >> 5;
42         packet_size =  gcw[0] & 0x03;
43
44 #ifdef CONFIG_PPC
45         /* kludge for Apple PowerBook internal zip */
46         if (drive->media == ide_floppy && device_type == 5 &&
47             !strstr((char *)&id[ATA_ID_PROD], "CD-ROM") &&
48             strstr((char *)&id[ATA_ID_PROD], "ZIP"))
49                 device_type = 0;
50 #endif
51
52         if (protocol != 2)
53                 printk(KERN_ERR "%s: %s: protocol (0x%02x) is not ATAPI\n",
54                         s, drive->name, protocol);
55         else if ((drive->media == ide_floppy && device_type != 0) ||
56                  (drive->media == ide_tape && device_type != 1))
57                 printk(KERN_ERR "%s: %s: invalid device type (0x%02x)\n",
58                         s, drive->name, device_type);
59         else if (removable == 0)
60                 printk(KERN_ERR "%s: %s: the removable flag is not set\n",
61                         s, drive->name);
62         else if (drive->media == ide_floppy && drq_type == 3)
63                 printk(KERN_ERR "%s: %s: sorry, DRQ type (0x%02x) not "
64                         "supported\n", s, drive->name, drq_type);
65         else if (packet_size != 0)
66                 printk(KERN_ERR "%s: %s: packet size (0x%02x) is not 12 "
67                         "bytes\n", s, drive->name, packet_size);
68         else
69                 return 1;
70         return 0;
71 }
72 EXPORT_SYMBOL_GPL(ide_check_atapi_device);
73
74 /* PIO data transfer routine using the scatter gather table. */
75 int ide_io_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
76                     unsigned int bcount, int write)
77 {
78         ide_hwif_t *hwif = drive->hwif;
79         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
80         xfer_func_t *xf = write ? tp_ops->output_data : tp_ops->input_data;
81         struct scatterlist *sg = pc->sg;
82         char *buf;
83         int count, done = 0;
84
85         while (bcount) {
86                 count = min(sg->length - pc->b_count, bcount);
87
88                 if (PageHighMem(sg_page(sg))) {
89                         unsigned long flags;
90
91                         local_irq_save(flags);
92                         buf = kmap_atomic(sg_page(sg), KM_IRQ0) + sg->offset;
93                         xf(drive, NULL, buf + pc->b_count, count);
94                         kunmap_atomic(buf - sg->offset, KM_IRQ0);
95                         local_irq_restore(flags);
96                 } else {
97                         buf = sg_virt(sg);
98                         xf(drive, NULL, buf + pc->b_count, count);
99                 }
100
101                 bcount -= count;
102                 pc->b_count += count;
103                 done += count;
104
105                 if (pc->b_count == sg->length) {
106                         if (!--pc->sg_cnt)
107                                 break;
108                         pc->sg = sg = sg_next(sg);
109                         pc->b_count = 0;
110                 }
111         }
112
113         if (bcount) {
114                 printk(KERN_ERR "%s: %d leftover bytes, %s\n", drive->name,
115                         bcount, write ? "padding with zeros"
116                                       : "discarding data");
117                 ide_pad_transfer(drive, write, bcount);
118         }
119
120         return done;
121 }
122 EXPORT_SYMBOL_GPL(ide_io_buffers);
123
124 void ide_init_pc(struct ide_atapi_pc *pc)
125 {
126         memset(pc, 0, sizeof(*pc));
127         pc->buf = pc->pc_buf;
128         pc->buf_size = IDE_PC_BUFFER_SIZE;
129 }
130 EXPORT_SYMBOL_GPL(ide_init_pc);
131
132 /*
133  * Generate a new packet command request in front of the request queue, before
134  * the current request, so that it will be processed immediately, on the next
135  * pass through the driver.
136  */
137 static void ide_queue_pc_head(ide_drive_t *drive, struct gendisk *disk,
138                               struct ide_atapi_pc *pc, struct request *rq)
139 {
140         blk_rq_init(NULL, rq);
141         rq->cmd_type = REQ_TYPE_SPECIAL;
142         rq->cmd_flags |= REQ_PREEMPT;
143         rq->buffer = (char *)pc;
144         rq->rq_disk = disk;
145
146         if (pc->req_xfer) {
147                 rq->data = pc->buf;
148                 rq->data_len = pc->req_xfer;
149         }
150
151         memcpy(rq->cmd, pc->c, 12);
152         if (drive->media == ide_tape)
153                 rq->cmd[13] = REQ_IDETAPE_PC1;
154
155         drive->hwif->rq = NULL;
156
157         elv_add_request(drive->queue, rq, ELEVATOR_INSERT_FRONT, 0);
158 }
159
160 /*
161  * Add a special packet command request to the tail of the request queue,
162  * and wait for it to be serviced.
163  */
164 int ide_queue_pc_tail(ide_drive_t *drive, struct gendisk *disk,
165                       struct ide_atapi_pc *pc)
166 {
167         struct request *rq;
168         int error;
169
170         rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
171         rq->cmd_type = REQ_TYPE_SPECIAL;
172         rq->buffer = (char *)pc;
173
174         if (pc->req_xfer) {
175                 rq->data = pc->buf;
176                 rq->data_len = pc->req_xfer;
177         }
178
179         memcpy(rq->cmd, pc->c, 12);
180         if (drive->media == ide_tape)
181                 rq->cmd[13] = REQ_IDETAPE_PC1;
182         error = blk_execute_rq(drive->queue, disk, rq, 0);
183         blk_put_request(rq);
184
185         return error;
186 }
187 EXPORT_SYMBOL_GPL(ide_queue_pc_tail);
188
189 int ide_do_test_unit_ready(ide_drive_t *drive, struct gendisk *disk)
190 {
191         struct ide_atapi_pc pc;
192
193         ide_init_pc(&pc);
194         pc.c[0] = TEST_UNIT_READY;
195
196         return ide_queue_pc_tail(drive, disk, &pc);
197 }
198 EXPORT_SYMBOL_GPL(ide_do_test_unit_ready);
199
200 int ide_do_start_stop(ide_drive_t *drive, struct gendisk *disk, int start)
201 {
202         struct ide_atapi_pc pc;
203
204         ide_init_pc(&pc);
205         pc.c[0] = START_STOP;
206         pc.c[4] = start;
207
208         if (drive->media == ide_tape)
209                 pc.flags |= PC_FLAG_WAIT_FOR_DSC;
210
211         return ide_queue_pc_tail(drive, disk, &pc);
212 }
213 EXPORT_SYMBOL_GPL(ide_do_start_stop);
214
215 int ide_set_media_lock(ide_drive_t *drive, struct gendisk *disk, int on)
216 {
217         struct ide_atapi_pc pc;
218
219         if ((drive->dev_flags & IDE_DFLAG_DOORLOCKING) == 0)
220                 return 0;
221
222         ide_init_pc(&pc);
223         pc.c[0] = ALLOW_MEDIUM_REMOVAL;
224         pc.c[4] = on;
225
226         return ide_queue_pc_tail(drive, disk, &pc);
227 }
228 EXPORT_SYMBOL_GPL(ide_set_media_lock);
229
230 void ide_create_request_sense_cmd(ide_drive_t *drive, struct ide_atapi_pc *pc)
231 {
232         ide_init_pc(pc);
233         pc->c[0] = REQUEST_SENSE;
234         if (drive->media == ide_floppy) {
235                 pc->c[4] = 255;
236                 pc->req_xfer = 18;
237         } else {
238                 pc->c[4] = 20;
239                 pc->req_xfer = 20;
240         }
241 }
242 EXPORT_SYMBOL_GPL(ide_create_request_sense_cmd);
243
244 /*
245  * Called when an error was detected during the last packet command.
246  * We queue a request sense packet command in the head of the request list.
247  */
248 void ide_retry_pc(ide_drive_t *drive, struct gendisk *disk)
249 {
250         struct request *rq = &drive->request_sense_rq;
251         struct ide_atapi_pc *pc = &drive->request_sense_pc;
252
253         (void)ide_read_error(drive);
254         ide_create_request_sense_cmd(drive, pc);
255         if (drive->media == ide_tape)
256                 set_bit(IDE_AFLAG_IGNORE_DSC, &drive->atapi_flags);
257         ide_queue_pc_head(drive, disk, pc, rq);
258 }
259 EXPORT_SYMBOL_GPL(ide_retry_pc);
260
261 int ide_cd_expiry(ide_drive_t *drive)
262 {
263         struct request *rq = drive->hwif->rq;
264         unsigned long wait = 0;
265
266         debug_log("%s: rq->cmd[0]: 0x%x\n", __func__, rq->cmd[0]);
267
268         /*
269          * Some commands are *slow* and normally take a long time to complete.
270          * Usually we can use the ATAPI "disconnect" to bypass this, but not all
271          * commands/drives support that. Let ide_timer_expiry keep polling us
272          * for these.
273          */
274         switch (rq->cmd[0]) {
275         case GPCMD_BLANK:
276         case GPCMD_FORMAT_UNIT:
277         case GPCMD_RESERVE_RZONE_TRACK:
278         case GPCMD_CLOSE_TRACK:
279         case GPCMD_FLUSH_CACHE:
280                 wait = ATAPI_WAIT_PC;
281                 break;
282         default:
283                 if (!(rq->cmd_flags & REQ_QUIET))
284                         printk(KERN_INFO "cmd 0x%x timed out\n",
285                                          rq->cmd[0]);
286                 wait = 0;
287                 break;
288         }
289         return wait;
290 }
291 EXPORT_SYMBOL_GPL(ide_cd_expiry);
292
293 int ide_cd_get_xferlen(struct request *rq)
294 {
295         if (blk_fs_request(rq))
296                 return 32768;
297         else if (blk_sense_request(rq) || blk_pc_request(rq) ||
298                          rq->cmd_type == REQ_TYPE_ATA_PC)
299                 return rq->data_len;
300         else
301                 return 0;
302 }
303 EXPORT_SYMBOL_GPL(ide_cd_get_xferlen);
304
305 void ide_read_bcount_and_ireason(ide_drive_t *drive, u16 *bcount, u8 *ireason)
306 {
307         struct ide_cmd cmd;
308
309         memset(&cmd, 0, sizeof(cmd));
310         cmd.tf_flags = IDE_TFLAG_IN_LBAH | IDE_TFLAG_IN_LBAM |
311                        IDE_TFLAG_IN_NSECT;
312
313         drive->hwif->tp_ops->tf_read(drive, &cmd);
314
315         *bcount = (cmd.tf.lbah << 8) | cmd.tf.lbam;
316         *ireason = cmd.tf.nsect & 3;
317 }
318 EXPORT_SYMBOL_GPL(ide_read_bcount_and_ireason);
319
320 /*
321  * This is the usual interrupt handler which will be called during a packet
322  * command.  We will transfer some of the data (as requested by the drive)
323  * and will re-point interrupt handler to us.
324  */
325 static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
326 {
327         struct ide_atapi_pc *pc = drive->pc;
328         ide_hwif_t *hwif = drive->hwif;
329         struct request *rq = hwif->rq;
330         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
331         xfer_func_t *xferfunc;
332         unsigned int timeout, temp;
333         u16 bcount;
334         u8 stat, ireason, dsc = 0;
335
336         debug_log("Enter %s - interrupt handler\n", __func__);
337
338         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
339                                                : WAIT_TAPE_CMD;
340
341         /* Clear the interrupt */
342         stat = tp_ops->read_status(hwif);
343
344         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
345                 if (hwif->dma_ops->dma_end(drive) ||
346                     (drive->media == ide_tape && (stat & ATA_ERR))) {
347                         if (drive->media == ide_floppy)
348                                 printk(KERN_ERR "%s: DMA %s error\n",
349                                         drive->name, rq_data_dir(pc->rq)
350                                                      ? "write" : "read");
351                         pc->flags |= PC_FLAG_DMA_ERROR;
352                 } else {
353                         pc->xferred = pc->req_xfer;
354                         if (drive->pc_update_buffers)
355                                 drive->pc_update_buffers(drive, pc);
356                 }
357                 debug_log("%s: DMA finished\n", drive->name);
358         }
359
360         /* No more interrupts */
361         if ((stat & ATA_DRQ) == 0) {
362                 int uptodate;
363
364                 debug_log("Packet command completed, %d bytes transferred\n",
365                           pc->xferred);
366
367                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
368
369                 local_irq_enable_in_hardirq();
370
371                 if (drive->media == ide_tape &&
372                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
373                         stat &= ~ATA_ERR;
374
375                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
376                         /* Error detected */
377                         debug_log("%s: I/O error\n", drive->name);
378
379                         if (drive->media != ide_tape)
380                                 pc->rq->errors++;
381
382                         if (rq->cmd[0] == REQUEST_SENSE) {
383                                 printk(KERN_ERR "%s: I/O error in request sense"
384                                                 " command\n", drive->name);
385                                 return ide_do_reset(drive);
386                         }
387
388                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
389
390                         /* Retry operation */
391                         ide_retry_pc(drive, rq->rq_disk);
392
393                         /* queued, but not started */
394                         return ide_stopped;
395                 }
396                 pc->error = 0;
397
398                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
399                         dsc = 1;
400
401                 /* Command finished - Call the callback function */
402                 uptodate = drive->pc_callback(drive, dsc);
403
404                 if (uptodate == 0)
405                         drive->failed_pc = NULL;
406
407                 if (blk_special_request(rq)) {
408                         rq->errors = 0;
409                         ide_complete_rq(drive, 0, blk_rq_bytes(rq));
410                 } else {
411                         if (blk_fs_request(rq) == 0 && uptodate <= 0) {
412                                 if (rq->errors == 0)
413                                         rq->errors = -EIO;
414                         }
415                         ide_complete_rq(drive, uptodate ? 0 : -EIO,
416                                         ide_rq_bytes(rq));
417                 }
418
419                 return ide_stopped;
420         }
421
422         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
423                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
424                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
425                                 "in DMA mode\n", drive->name);
426                 ide_dma_off(drive);
427                 return ide_do_reset(drive);
428         }
429
430         /* Get the number of bytes to transfer on this interrupt. */
431         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
432
433         if (ireason & ATAPI_COD) {
434                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
435                 return ide_do_reset(drive);
436         }
437
438         if (((ireason & ATAPI_IO) == ATAPI_IO) ==
439                 !!(pc->flags & PC_FLAG_WRITING)) {
440                 /* Hopefully, we will never get here */
441                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
442                                 "to %s!\n", drive->name,
443                                 (ireason & ATAPI_IO) ? "Write" : "Read",
444                                 (ireason & ATAPI_IO) ? "Read" : "Write");
445                 return ide_do_reset(drive);
446         }
447
448         if (!(pc->flags & PC_FLAG_WRITING)) {
449                 /* Reading - Check that we have enough space */
450                 temp = pc->xferred + bcount;
451                 if (temp > pc->req_xfer) {
452                         if (temp > pc->buf_size) {
453                                 printk(KERN_ERR "%s: The device wants to send "
454                                                 "us more data than expected - "
455                                                 "discarding data\n",
456                                                 drive->name);
457
458                                 ide_pad_transfer(drive, 0, bcount);
459                                 goto next_irq;
460                         }
461                         debug_log("The device wants to send us more data than "
462                                   "expected - allowing transfer\n");
463                 }
464                 xferfunc = tp_ops->input_data;
465         } else
466                 xferfunc = tp_ops->output_data;
467
468         if ((drive->media == ide_floppy && !pc->buf) ||
469             (drive->media == ide_tape && pc->bh)) {
470                 int done = drive->pc_io_buffers(drive, pc, bcount,
471                                   !!(pc->flags & PC_FLAG_WRITING));
472
473                 /* FIXME: don't do partial completions */
474                 if (drive->media == ide_floppy)
475                         ide_complete_rq(drive, 0,
476                                         done ? done : ide_rq_bytes(rq));
477         } else
478                 xferfunc(drive, NULL, pc->cur_pos, bcount);
479
480         /* Update the current position */
481         pc->xferred += bcount;
482         pc->cur_pos += bcount;
483
484         debug_log("[cmd %x] transferred %d bytes on that intr.\n",
485                   rq->cmd[0], bcount);
486 next_irq:
487         /* And set the interrupt handler again */
488         ide_set_handler(drive, ide_pc_intr, timeout);
489         return ide_started;
490 }
491
492 static void ide_init_packet_cmd(struct ide_cmd *cmd, u32 tf_flags,
493                                 u16 bcount, u8 dma)
494 {
495         cmd->protocol  = dma ? ATAPI_PROT_DMA : ATAPI_PROT_PIO;
496         cmd->tf_flags |= IDE_TFLAG_OUT_LBAH | IDE_TFLAG_OUT_LBAM |
497                          IDE_TFLAG_OUT_FEATURE | tf_flags;
498         cmd->tf.command = ATA_CMD_PACKET;
499         cmd->tf.feature = dma;          /* Use PIO/DMA */
500         cmd->tf.lbam    = bcount & 0xff;
501         cmd->tf.lbah    = (bcount >> 8) & 0xff;
502 }
503
504 static u8 ide_read_ireason(ide_drive_t *drive)
505 {
506         struct ide_cmd cmd;
507
508         memset(&cmd, 0, sizeof(cmd));
509         cmd.tf_flags = IDE_TFLAG_IN_NSECT;
510
511         drive->hwif->tp_ops->tf_read(drive, &cmd);
512
513         return cmd.tf.nsect & 3;
514 }
515
516 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
517 {
518         int retries = 100;
519
520         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
521                 (ireason & ATAPI_IO))) {
522                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
523                                 "a packet command, retrying\n", drive->name);
524                 udelay(100);
525                 ireason = ide_read_ireason(drive);
526                 if (retries == 0) {
527                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
528                                         "a packet command, ignoring\n",
529                                         drive->name);
530                         ireason |= ATAPI_COD;
531                         ireason &= ~ATAPI_IO;
532                 }
533         }
534
535         return ireason;
536 }
537
538 static int ide_delayed_transfer_pc(ide_drive_t *drive)
539 {
540         /* Send the actual packet */
541         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
542
543         /* Timeout for the packet command */
544         return WAIT_FLOPPY_CMD;
545 }
546
547 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
548 {
549         struct ide_atapi_pc *uninitialized_var(pc);
550         ide_hwif_t *hwif = drive->hwif;
551         struct request *rq = hwif->rq;
552         ide_expiry_t *expiry;
553         unsigned int timeout;
554         int cmd_len;
555         ide_startstop_t startstop;
556         u8 ireason;
557
558         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
559                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
560                                 "DRQ isn't asserted\n", drive->name);
561                 return startstop;
562         }
563
564         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
565                 if (drive->dma)
566                         drive->waiting_for_dma = 1;
567         }
568
569         if (dev_is_idecd(drive)) {
570                 /* ATAPI commands get padded out to 12 bytes minimum */
571                 cmd_len = COMMAND_SIZE(rq->cmd[0]);
572                 if (cmd_len < ATAPI_MIN_CDB_BYTES)
573                         cmd_len = ATAPI_MIN_CDB_BYTES;
574
575                 timeout = rq->timeout;
576                 expiry  = ide_cd_expiry;
577         } else {
578                 pc = drive->pc;
579
580                 cmd_len = ATAPI_MIN_CDB_BYTES;
581
582                 /*
583                  * If necessary schedule the packet transfer to occur 'timeout'
584                  * miliseconds later in ide_delayed_transfer_pc() after the
585                  * device says it's ready for a packet.
586                  */
587                 if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
588                         timeout = drive->pc_delay;
589                         expiry = &ide_delayed_transfer_pc;
590                 } else {
591                         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
592                                                                : WAIT_TAPE_CMD;
593                         expiry = NULL;
594                 }
595
596                 ireason = ide_read_ireason(drive);
597                 if (drive->media == ide_tape)
598                         ireason = ide_wait_ireason(drive, ireason);
599
600                 if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
601                         printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
602                                         "a packet command\n", drive->name);
603
604                         return ide_do_reset(drive);
605                 }
606         }
607
608         hwif->expiry = expiry;
609
610         /* Set the interrupt routine */
611         ide_set_handler(drive,
612                         (dev_is_idecd(drive) ? drive->irq_handler
613                                              : ide_pc_intr),
614                         timeout);
615
616         /* Send the actual packet */
617         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
618                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
619
620         /* Begin DMA, if necessary */
621         if (dev_is_idecd(drive)) {
622                 if (drive->dma)
623                         hwif->dma_ops->dma_start(drive);
624         } else {
625                 if (pc->flags & PC_FLAG_DMA_OK) {
626                         pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
627                         hwif->dma_ops->dma_start(drive);
628                 }
629         }
630
631         return ide_started;
632 }
633
634 ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
635 {
636         struct ide_atapi_pc *pc;
637         ide_hwif_t *hwif = drive->hwif;
638         const struct ide_dma_ops *dma_ops = hwif->dma_ops;
639         ide_expiry_t *expiry = NULL;
640         struct request *rq = hwif->rq;
641         unsigned int timeout;
642         u32 tf_flags;
643         u16 bcount;
644         u8 drq_int = !!(drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT);
645
646         if (dev_is_idecd(drive)) {
647                 tf_flags = IDE_TFLAG_OUT_NSECT | IDE_TFLAG_OUT_LBAL;
648                 bcount = ide_cd_get_xferlen(rq);
649                 expiry = ide_cd_expiry;
650                 timeout = ATAPI_WAIT_PC;
651
652                 if (drive->dma) {
653                         if (ide_build_sglist(drive, cmd))
654                                 drive->dma = !dma_ops->dma_setup(drive, cmd);
655                         else
656                                 drive->dma = 0;
657                 }
658         } else {
659                 pc = drive->pc;
660
661                 /* We haven't transferred any data yet */
662                 pc->xferred = 0;
663                 pc->cur_pos = pc->buf;
664
665                 tf_flags = IDE_TFLAG_OUT_DEVICE;
666                 bcount = ((drive->media == ide_tape) ?
667                                 pc->req_xfer :
668                                 min(pc->req_xfer, 63 * 1024));
669
670                 if (pc->flags & PC_FLAG_DMA_ERROR) {
671                         pc->flags &= ~PC_FLAG_DMA_ERROR;
672                         ide_dma_off(drive);
673                 }
674
675                 if ((pc->flags & PC_FLAG_DMA_OK) &&
676                      (drive->dev_flags & IDE_DFLAG_USING_DMA)) {
677                         if (ide_build_sglist(drive, cmd))
678                                 drive->dma = !dma_ops->dma_setup(drive, cmd);
679                         else
680                                 drive->dma = 0;
681                 }
682
683                 if (!drive->dma)
684                         pc->flags &= ~PC_FLAG_DMA_OK;
685
686                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
687                                                        : WAIT_TAPE_CMD;
688         }
689
690         ide_init_packet_cmd(cmd, tf_flags, bcount, drive->dma);
691
692         (void)do_rw_taskfile(drive, cmd);
693
694         if (drq_int) {
695                 if (drive->dma)
696                         drive->waiting_for_dma = 0;
697                 hwif->expiry = expiry;
698         }
699
700         ide_execute_command(drive, cmd, ide_transfer_pc, timeout);
701
702         return drq_int ? ide_started : ide_transfer_pc(drive);
703 }
704 EXPORT_SYMBOL_GPL(ide_issue_pc);