ide: add ide_dma_prepare() helper
[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                 int rc = hwif->dma_ops->dma_end(drive);
346
347                 ide_destroy_dmatable(drive);
348
349                 if (rc || (drive->media == ide_tape && (stat & ATA_ERR))) {
350                         if (drive->media == ide_floppy)
351                                 printk(KERN_ERR "%s: DMA %s error\n",
352                                         drive->name, rq_data_dir(pc->rq)
353                                                      ? "write" : "read");
354                         pc->flags |= PC_FLAG_DMA_ERROR;
355                 } else {
356                         pc->xferred = pc->req_xfer;
357                         if (drive->pc_update_buffers)
358                                 drive->pc_update_buffers(drive, pc);
359                 }
360                 debug_log("%s: DMA finished\n", drive->name);
361         }
362
363         /* No more interrupts */
364         if ((stat & ATA_DRQ) == 0) {
365                 int uptodate;
366
367                 debug_log("Packet command completed, %d bytes transferred\n",
368                           pc->xferred);
369
370                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
371
372                 local_irq_enable_in_hardirq();
373
374                 if (drive->media == ide_tape &&
375                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
376                         stat &= ~ATA_ERR;
377
378                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
379                         /* Error detected */
380                         debug_log("%s: I/O error\n", drive->name);
381
382                         if (drive->media != ide_tape)
383                                 pc->rq->errors++;
384
385                         if (rq->cmd[0] == REQUEST_SENSE) {
386                                 printk(KERN_ERR "%s: I/O error in request sense"
387                                                 " command\n", drive->name);
388                                 return ide_do_reset(drive);
389                         }
390
391                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
392
393                         /* Retry operation */
394                         ide_retry_pc(drive, rq->rq_disk);
395
396                         /* queued, but not started */
397                         return ide_stopped;
398                 }
399                 pc->error = 0;
400
401                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
402                         dsc = 1;
403
404                 /* Command finished - Call the callback function */
405                 uptodate = drive->pc_callback(drive, dsc);
406
407                 if (uptodate == 0)
408                         drive->failed_pc = NULL;
409
410                 if (blk_special_request(rq)) {
411                         rq->errors = 0;
412                         ide_complete_rq(drive, 0, blk_rq_bytes(rq));
413                 } else {
414                         if (blk_fs_request(rq) == 0 && uptodate <= 0) {
415                                 if (rq->errors == 0)
416                                         rq->errors = -EIO;
417                         }
418                         ide_complete_rq(drive, uptodate ? 0 : -EIO,
419                                         ide_rq_bytes(rq));
420                 }
421
422                 return ide_stopped;
423         }
424
425         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
426                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
427                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
428                                 "in DMA mode\n", drive->name);
429                 ide_dma_off(drive);
430                 return ide_do_reset(drive);
431         }
432
433         /* Get the number of bytes to transfer on this interrupt. */
434         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
435
436         if (ireason & ATAPI_COD) {
437                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
438                 return ide_do_reset(drive);
439         }
440
441         if (((ireason & ATAPI_IO) == ATAPI_IO) ==
442                 !!(pc->flags & PC_FLAG_WRITING)) {
443                 /* Hopefully, we will never get here */
444                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
445                                 "to %s!\n", drive->name,
446                                 (ireason & ATAPI_IO) ? "Write" : "Read",
447                                 (ireason & ATAPI_IO) ? "Read" : "Write");
448                 return ide_do_reset(drive);
449         }
450
451         if (!(pc->flags & PC_FLAG_WRITING)) {
452                 /* Reading - Check that we have enough space */
453                 temp = pc->xferred + bcount;
454                 if (temp > pc->req_xfer) {
455                         if (temp > pc->buf_size) {
456                                 printk(KERN_ERR "%s: The device wants to send "
457                                                 "us more data than expected - "
458                                                 "discarding data\n",
459                                                 drive->name);
460
461                                 ide_pad_transfer(drive, 0, bcount);
462                                 goto next_irq;
463                         }
464                         debug_log("The device wants to send us more data than "
465                                   "expected - allowing transfer\n");
466                 }
467                 xferfunc = tp_ops->input_data;
468         } else
469                 xferfunc = tp_ops->output_data;
470
471         if ((drive->media == ide_floppy && !pc->buf) ||
472             (drive->media == ide_tape && pc->bh)) {
473                 int done = drive->pc_io_buffers(drive, pc, bcount,
474                                   !!(pc->flags & PC_FLAG_WRITING));
475
476                 /* FIXME: don't do partial completions */
477                 if (drive->media == ide_floppy)
478                         ide_complete_rq(drive, 0,
479                                         done ? done : ide_rq_bytes(rq));
480         } else
481                 xferfunc(drive, NULL, pc->cur_pos, bcount);
482
483         /* Update the current position */
484         pc->xferred += bcount;
485         pc->cur_pos += bcount;
486
487         debug_log("[cmd %x] transferred %d bytes on that intr.\n",
488                   rq->cmd[0], bcount);
489 next_irq:
490         /* And set the interrupt handler again */
491         ide_set_handler(drive, ide_pc_intr, timeout);
492         return ide_started;
493 }
494
495 static void ide_init_packet_cmd(struct ide_cmd *cmd, u32 tf_flags,
496                                 u16 bcount, u8 dma)
497 {
498         cmd->protocol  = dma ? ATAPI_PROT_DMA : ATAPI_PROT_PIO;
499         cmd->tf_flags |= IDE_TFLAG_OUT_LBAH | IDE_TFLAG_OUT_LBAM |
500                          IDE_TFLAG_OUT_FEATURE | tf_flags;
501         cmd->tf.command = ATA_CMD_PACKET;
502         cmd->tf.feature = dma;          /* Use PIO/DMA */
503         cmd->tf.lbam    = bcount & 0xff;
504         cmd->tf.lbah    = (bcount >> 8) & 0xff;
505 }
506
507 static u8 ide_read_ireason(ide_drive_t *drive)
508 {
509         struct ide_cmd cmd;
510
511         memset(&cmd, 0, sizeof(cmd));
512         cmd.tf_flags = IDE_TFLAG_IN_NSECT;
513
514         drive->hwif->tp_ops->tf_read(drive, &cmd);
515
516         return cmd.tf.nsect & 3;
517 }
518
519 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
520 {
521         int retries = 100;
522
523         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
524                 (ireason & ATAPI_IO))) {
525                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
526                                 "a packet command, retrying\n", drive->name);
527                 udelay(100);
528                 ireason = ide_read_ireason(drive);
529                 if (retries == 0) {
530                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
531                                         "a packet command, ignoring\n",
532                                         drive->name);
533                         ireason |= ATAPI_COD;
534                         ireason &= ~ATAPI_IO;
535                 }
536         }
537
538         return ireason;
539 }
540
541 static int ide_delayed_transfer_pc(ide_drive_t *drive)
542 {
543         /* Send the actual packet */
544         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
545
546         /* Timeout for the packet command */
547         return WAIT_FLOPPY_CMD;
548 }
549
550 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
551 {
552         struct ide_atapi_pc *uninitialized_var(pc);
553         ide_hwif_t *hwif = drive->hwif;
554         struct request *rq = hwif->rq;
555         ide_expiry_t *expiry;
556         unsigned int timeout;
557         int cmd_len;
558         ide_startstop_t startstop;
559         u8 ireason;
560
561         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
562                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
563                                 "DRQ isn't asserted\n", drive->name);
564                 return startstop;
565         }
566
567         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
568                 if (drive->dma)
569                         drive->waiting_for_dma = 1;
570         }
571
572         if (dev_is_idecd(drive)) {
573                 /* ATAPI commands get padded out to 12 bytes minimum */
574                 cmd_len = COMMAND_SIZE(rq->cmd[0]);
575                 if (cmd_len < ATAPI_MIN_CDB_BYTES)
576                         cmd_len = ATAPI_MIN_CDB_BYTES;
577
578                 timeout = rq->timeout;
579                 expiry  = ide_cd_expiry;
580         } else {
581                 pc = drive->pc;
582
583                 cmd_len = ATAPI_MIN_CDB_BYTES;
584
585                 /*
586                  * If necessary schedule the packet transfer to occur 'timeout'
587                  * miliseconds later in ide_delayed_transfer_pc() after the
588                  * device says it's ready for a packet.
589                  */
590                 if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
591                         timeout = drive->pc_delay;
592                         expiry = &ide_delayed_transfer_pc;
593                 } else {
594                         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
595                                                                : WAIT_TAPE_CMD;
596                         expiry = NULL;
597                 }
598
599                 ireason = ide_read_ireason(drive);
600                 if (drive->media == ide_tape)
601                         ireason = ide_wait_ireason(drive, ireason);
602
603                 if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
604                         printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
605                                         "a packet command\n", drive->name);
606
607                         return ide_do_reset(drive);
608                 }
609         }
610
611         hwif->expiry = expiry;
612
613         /* Set the interrupt routine */
614         ide_set_handler(drive,
615                         (dev_is_idecd(drive) ? drive->irq_handler
616                                              : ide_pc_intr),
617                         timeout);
618
619         /* Send the actual packet */
620         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
621                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
622
623         /* Begin DMA, if necessary */
624         if (dev_is_idecd(drive)) {
625                 if (drive->dma)
626                         hwif->dma_ops->dma_start(drive);
627         } else {
628                 if (pc->flags & PC_FLAG_DMA_OK) {
629                         pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
630                         hwif->dma_ops->dma_start(drive);
631                 }
632         }
633
634         return ide_started;
635 }
636
637 ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
638 {
639         struct ide_atapi_pc *pc;
640         ide_hwif_t *hwif = drive->hwif;
641         ide_expiry_t *expiry = NULL;
642         struct request *rq = hwif->rq;
643         unsigned int timeout;
644         u32 tf_flags;
645         u16 bcount;
646         u8 drq_int = !!(drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT);
647
648         if (dev_is_idecd(drive)) {
649                 tf_flags = IDE_TFLAG_OUT_NSECT | IDE_TFLAG_OUT_LBAL;
650                 bcount = ide_cd_get_xferlen(rq);
651                 expiry = ide_cd_expiry;
652                 timeout = ATAPI_WAIT_PC;
653
654                 if (drive->dma)
655                         drive->dma = !ide_dma_prepare(drive, cmd);
656         } else {
657                 pc = drive->pc;
658
659                 /* We haven't transferred any data yet */
660                 pc->xferred = 0;
661                 pc->cur_pos = pc->buf;
662
663                 tf_flags = IDE_TFLAG_OUT_DEVICE;
664                 bcount = ((drive->media == ide_tape) ?
665                                 pc->req_xfer :
666                                 min(pc->req_xfer, 63 * 1024));
667
668                 if (pc->flags & PC_FLAG_DMA_ERROR) {
669                         pc->flags &= ~PC_FLAG_DMA_ERROR;
670                         ide_dma_off(drive);
671                 }
672
673                 if (pc->flags & PC_FLAG_DMA_OK)
674                         drive->dma = !ide_dma_prepare(drive, cmd);
675
676                 if (!drive->dma)
677                         pc->flags &= ~PC_FLAG_DMA_OK;
678
679                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
680                                                        : WAIT_TAPE_CMD;
681         }
682
683         ide_init_packet_cmd(cmd, tf_flags, bcount, drive->dma);
684
685         (void)do_rw_taskfile(drive, cmd);
686
687         if (drq_int) {
688                 if (drive->dma)
689                         drive->waiting_for_dma = 0;
690                 hwif->expiry = expiry;
691         }
692
693         ide_execute_command(drive, cmd, ide_transfer_pc, timeout);
694
695         return drq_int ? ide_started : ide_transfer_pc(drive);
696 }
697 EXPORT_SYMBOL_GPL(ide_issue_pc);