Merge branch 'for-linus' of git://oss.sgi.com/xfs/xfs
[linux-2.6] / drivers / ide / ide-io.c
1 /*
2  *      IDE I/O functions
3  *
4  *      Basic PIO and command management functionality.
5  *
6  * This code was split off from ide.c. See ide.c for history and original
7  * copyrights.
8  *
9  * This program is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU General Public License as published by the
11  * Free Software Foundation; either version 2, or (at your option) any
12  * later version.
13  *
14  * This program is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17  * General Public License for more details.
18  *
19  * For the avoidance of doubt the "preferred form" of this code is one which
20  * is in an open non patent encumbered format. Where cryptographic key signing
21  * forms part of the process of creating an executable the information
22  * including keys needed to generate an equivalently functional executable
23  * are deemed to be part of the source code.
24  */
25  
26  
27 #include <linux/module.h>
28 #include <linux/types.h>
29 #include <linux/string.h>
30 #include <linux/kernel.h>
31 #include <linux/timer.h>
32 #include <linux/mm.h>
33 #include <linux/interrupt.h>
34 #include <linux/major.h>
35 #include <linux/errno.h>
36 #include <linux/genhd.h>
37 #include <linux/blkpg.h>
38 #include <linux/slab.h>
39 #include <linux/init.h>
40 #include <linux/pci.h>
41 #include <linux/delay.h>
42 #include <linux/ide.h>
43 #include <linux/hdreg.h>
44 #include <linux/completion.h>
45 #include <linux/reboot.h>
46 #include <linux/cdrom.h>
47 #include <linux/seq_file.h>
48 #include <linux/device.h>
49 #include <linux/kmod.h>
50 #include <linux/scatterlist.h>
51 #include <linux/bitops.h>
52
53 #include <asm/byteorder.h>
54 #include <asm/irq.h>
55 #include <asm/uaccess.h>
56 #include <asm/io.h>
57
58 static int __ide_end_request(ide_drive_t *drive, struct request *rq,
59                              int uptodate, unsigned int nr_bytes, int dequeue)
60 {
61         int ret = 1;
62         int error = 0;
63
64         if (uptodate <= 0)
65                 error = uptodate ? uptodate : -EIO;
66
67         /*
68          * if failfast is set on a request, override number of sectors and
69          * complete the whole request right now
70          */
71         if (blk_noretry_request(rq) && error)
72                 nr_bytes = rq->hard_nr_sectors << 9;
73
74         if (!blk_fs_request(rq) && error && !rq->errors)
75                 rq->errors = -EIO;
76
77         /*
78          * decide whether to reenable DMA -- 3 is a random magic for now,
79          * if we DMA timeout more than 3 times, just stay in PIO
80          */
81         if ((drive->dev_flags & IDE_DFLAG_DMA_PIO_RETRY) &&
82             drive->retry_pio <= 3) {
83                 drive->dev_flags &= ~IDE_DFLAG_DMA_PIO_RETRY;
84                 ide_dma_on(drive);
85         }
86
87         if (!blk_end_request(rq, error, nr_bytes))
88                 ret = 0;
89
90         if (ret == 0 && dequeue)
91                 drive->hwif->hwgroup->rq = NULL;
92
93         return ret;
94 }
95
96 /**
97  *      ide_end_request         -       complete an IDE I/O
98  *      @drive: IDE device for the I/O
99  *      @uptodate:
100  *      @nr_sectors: number of sectors completed
101  *
102  *      This is our end_request wrapper function. We complete the I/O
103  *      update random number input and dequeue the request, which if
104  *      it was tagged may be out of order.
105  */
106
107 int ide_end_request (ide_drive_t *drive, int uptodate, int nr_sectors)
108 {
109         unsigned int nr_bytes = nr_sectors << 9;
110         struct request *rq = drive->hwif->hwgroup->rq;
111
112         if (!nr_bytes) {
113                 if (blk_pc_request(rq))
114                         nr_bytes = rq->data_len;
115                 else
116                         nr_bytes = rq->hard_cur_sectors << 9;
117         }
118
119         return __ide_end_request(drive, rq, uptodate, nr_bytes, 1);
120 }
121 EXPORT_SYMBOL(ide_end_request);
122
123 /**
124  *      ide_end_dequeued_request        -       complete an IDE I/O
125  *      @drive: IDE device for the I/O
126  *      @uptodate:
127  *      @nr_sectors: number of sectors completed
128  *
129  *      Complete an I/O that is no longer on the request queue. This
130  *      typically occurs when we pull the request and issue a REQUEST_SENSE.
131  *      We must still finish the old request but we must not tamper with the
132  *      queue in the meantime.
133  *
134  *      NOTE: This path does not handle barrier, but barrier is not supported
135  *      on ide-cd anyway.
136  */
137
138 int ide_end_dequeued_request(ide_drive_t *drive, struct request *rq,
139                              int uptodate, int nr_sectors)
140 {
141         BUG_ON(!blk_rq_started(rq));
142
143         return __ide_end_request(drive, rq, uptodate, nr_sectors << 9, 0);
144 }
145 EXPORT_SYMBOL_GPL(ide_end_dequeued_request);
146
147 /**
148  *      ide_end_drive_cmd       -       end an explicit drive command
149  *      @drive: command 
150  *      @stat: status bits
151  *      @err: error bits
152  *
153  *      Clean up after success/failure of an explicit drive command.
154  *      These get thrown onto the queue so they are synchronized with
155  *      real I/O operations on the drive.
156  *
157  *      In LBA48 mode we have to read the register set twice to get
158  *      all the extra information out.
159  */
160  
161 void ide_end_drive_cmd (ide_drive_t *drive, u8 stat, u8 err)
162 {
163         ide_hwgroup_t *hwgroup = drive->hwif->hwgroup;
164         struct request *rq = hwgroup->rq;
165
166         if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE) {
167                 ide_task_t *task = (ide_task_t *)rq->special;
168
169                 if (task) {
170                         struct ide_taskfile *tf = &task->tf;
171
172                         tf->error = err;
173                         tf->status = stat;
174
175                         drive->hwif->tp_ops->tf_read(drive, task);
176
177                         if (task->tf_flags & IDE_TFLAG_DYN)
178                                 kfree(task);
179                 }
180         } else if (blk_pm_request(rq)) {
181                 struct request_pm_state *pm = rq->data;
182
183                 ide_complete_power_step(drive, rq);
184                 if (pm->pm_step == IDE_PM_COMPLETED)
185                         ide_complete_pm_request(drive, rq);
186                 return;
187         }
188
189         hwgroup->rq = NULL;
190
191         rq->errors = err;
192
193         if (unlikely(blk_end_request(rq, (rq->errors ? -EIO : 0),
194                                      blk_rq_bytes(rq))))
195                 BUG();
196 }
197 EXPORT_SYMBOL(ide_end_drive_cmd);
198
199 static void ide_kill_rq(ide_drive_t *drive, struct request *rq)
200 {
201         if (rq->rq_disk) {
202                 ide_driver_t *drv;
203
204                 drv = *(ide_driver_t **)rq->rq_disk->private_data;
205                 drv->end_request(drive, 0, 0);
206         } else
207                 ide_end_request(drive, 0, 0);
208 }
209
210 static ide_startstop_t ide_ata_error(ide_drive_t *drive, struct request *rq, u8 stat, u8 err)
211 {
212         ide_hwif_t *hwif = drive->hwif;
213
214         if ((stat & ATA_BUSY) ||
215             ((stat & ATA_DF) && (drive->dev_flags & IDE_DFLAG_NOWERR) == 0)) {
216                 /* other bits are useless when BUSY */
217                 rq->errors |= ERROR_RESET;
218         } else if (stat & ATA_ERR) {
219                 /* err has different meaning on cdrom and tape */
220                 if (err == ATA_ABORTED) {
221                         if ((drive->dev_flags & IDE_DFLAG_LBA) &&
222                             /* some newer drives don't support ATA_CMD_INIT_DEV_PARAMS */
223                             hwif->tp_ops->read_status(hwif) == ATA_CMD_INIT_DEV_PARAMS)
224                                 return ide_stopped;
225                 } else if ((err & BAD_CRC) == BAD_CRC) {
226                         /* UDMA crc error, just retry the operation */
227                         drive->crc_count++;
228                 } else if (err & (ATA_BBK | ATA_UNC)) {
229                         /* retries won't help these */
230                         rq->errors = ERROR_MAX;
231                 } else if (err & ATA_TRK0NF) {
232                         /* help it find track zero */
233                         rq->errors |= ERROR_RECAL;
234                 }
235         }
236
237         if ((stat & ATA_DRQ) && rq_data_dir(rq) == READ &&
238             (hwif->host_flags & IDE_HFLAG_ERROR_STOPS_FIFO) == 0) {
239                 int nsect = drive->mult_count ? drive->mult_count : 1;
240
241                 ide_pad_transfer(drive, READ, nsect * SECTOR_SIZE);
242         }
243
244         if (rq->errors >= ERROR_MAX || blk_noretry_request(rq)) {
245                 ide_kill_rq(drive, rq);
246                 return ide_stopped;
247         }
248
249         if (hwif->tp_ops->read_status(hwif) & (ATA_BUSY | ATA_DRQ))
250                 rq->errors |= ERROR_RESET;
251
252         if ((rq->errors & ERROR_RESET) == ERROR_RESET) {
253                 ++rq->errors;
254                 return ide_do_reset(drive);
255         }
256
257         if ((rq->errors & ERROR_RECAL) == ERROR_RECAL)
258                 drive->special.b.recalibrate = 1;
259
260         ++rq->errors;
261
262         return ide_stopped;
263 }
264
265 static ide_startstop_t ide_atapi_error(ide_drive_t *drive, struct request *rq, u8 stat, u8 err)
266 {
267         ide_hwif_t *hwif = drive->hwif;
268
269         if ((stat & ATA_BUSY) ||
270             ((stat & ATA_DF) && (drive->dev_flags & IDE_DFLAG_NOWERR) == 0)) {
271                 /* other bits are useless when BUSY */
272                 rq->errors |= ERROR_RESET;
273         } else {
274                 /* add decoding error stuff */
275         }
276
277         if (hwif->tp_ops->read_status(hwif) & (ATA_BUSY | ATA_DRQ))
278                 /* force an abort */
279                 hwif->tp_ops->exec_command(hwif, ATA_CMD_IDLEIMMEDIATE);
280
281         if (rq->errors >= ERROR_MAX) {
282                 ide_kill_rq(drive, rq);
283         } else {
284                 if ((rq->errors & ERROR_RESET) == ERROR_RESET) {
285                         ++rq->errors;
286                         return ide_do_reset(drive);
287                 }
288                 ++rq->errors;
289         }
290
291         return ide_stopped;
292 }
293
294 ide_startstop_t
295 __ide_error(ide_drive_t *drive, struct request *rq, u8 stat, u8 err)
296 {
297         if (drive->media == ide_disk)
298                 return ide_ata_error(drive, rq, stat, err);
299         return ide_atapi_error(drive, rq, stat, err);
300 }
301
302 EXPORT_SYMBOL_GPL(__ide_error);
303
304 /**
305  *      ide_error       -       handle an error on the IDE
306  *      @drive: drive the error occurred on
307  *      @msg: message to report
308  *      @stat: status bits
309  *
310  *      ide_error() takes action based on the error returned by the drive.
311  *      For normal I/O that may well include retries. We deal with
312  *      both new-style (taskfile) and old style command handling here.
313  *      In the case of taskfile command handling there is work left to
314  *      do
315  */
316  
317 ide_startstop_t ide_error (ide_drive_t *drive, const char *msg, u8 stat)
318 {
319         struct request *rq;
320         u8 err;
321
322         err = ide_dump_status(drive, msg, stat);
323
324         if ((rq = HWGROUP(drive)->rq) == NULL)
325                 return ide_stopped;
326
327         /* retry only "normal" I/O: */
328         if (!blk_fs_request(rq)) {
329                 rq->errors = 1;
330                 ide_end_drive_cmd(drive, stat, err);
331                 return ide_stopped;
332         }
333
334         if (rq->rq_disk) {
335                 ide_driver_t *drv;
336
337                 drv = *(ide_driver_t **)rq->rq_disk->private_data;
338                 return drv->error(drive, rq, stat, err);
339         } else
340                 return __ide_error(drive, rq, stat, err);
341 }
342
343 EXPORT_SYMBOL_GPL(ide_error);
344
345 static void ide_tf_set_specify_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
346 {
347         tf->nsect   = drive->sect;
348         tf->lbal    = drive->sect;
349         tf->lbam    = drive->cyl;
350         tf->lbah    = drive->cyl >> 8;
351         tf->device  = (drive->head - 1) | drive->select;
352         tf->command = ATA_CMD_INIT_DEV_PARAMS;
353 }
354
355 static void ide_tf_set_restore_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
356 {
357         tf->nsect   = drive->sect;
358         tf->command = ATA_CMD_RESTORE;
359 }
360
361 static void ide_tf_set_setmult_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
362 {
363         tf->nsect   = drive->mult_req;
364         tf->command = ATA_CMD_SET_MULTI;
365 }
366
367 static ide_startstop_t ide_disk_special(ide_drive_t *drive)
368 {
369         special_t *s = &drive->special;
370         ide_task_t args;
371
372         memset(&args, 0, sizeof(ide_task_t));
373         args.data_phase = TASKFILE_NO_DATA;
374
375         if (s->b.set_geometry) {
376                 s->b.set_geometry = 0;
377                 ide_tf_set_specify_cmd(drive, &args.tf);
378         } else if (s->b.recalibrate) {
379                 s->b.recalibrate = 0;
380                 ide_tf_set_restore_cmd(drive, &args.tf);
381         } else if (s->b.set_multmode) {
382                 s->b.set_multmode = 0;
383                 ide_tf_set_setmult_cmd(drive, &args.tf);
384         } else if (s->all) {
385                 int special = s->all;
386                 s->all = 0;
387                 printk(KERN_ERR "%s: bad special flag: 0x%02x\n", drive->name, special);
388                 return ide_stopped;
389         }
390
391         args.tf_flags = IDE_TFLAG_TF | IDE_TFLAG_DEVICE |
392                         IDE_TFLAG_CUSTOM_HANDLER;
393
394         do_rw_taskfile(drive, &args);
395
396         return ide_started;
397 }
398
399 /**
400  *      do_special              -       issue some special commands
401  *      @drive: drive the command is for
402  *
403  *      do_special() is used to issue ATA_CMD_INIT_DEV_PARAMS,
404  *      ATA_CMD_RESTORE and ATA_CMD_SET_MULTI commands to a drive.
405  *
406  *      It used to do much more, but has been scaled back.
407  */
408
409 static ide_startstop_t do_special (ide_drive_t *drive)
410 {
411         special_t *s = &drive->special;
412
413 #ifdef DEBUG
414         printk("%s: do_special: 0x%02x\n", drive->name, s->all);
415 #endif
416         if (drive->media == ide_disk)
417                 return ide_disk_special(drive);
418
419         s->all = 0;
420         drive->mult_req = 0;
421         return ide_stopped;
422 }
423
424 void ide_map_sg(ide_drive_t *drive, struct request *rq)
425 {
426         ide_hwif_t *hwif = drive->hwif;
427         struct scatterlist *sg = hwif->sg_table;
428
429         if (hwif->sg_mapped)    /* needed by ide-scsi */
430                 return;
431
432         if (rq->cmd_type != REQ_TYPE_ATA_TASKFILE) {
433                 hwif->sg_nents = blk_rq_map_sg(drive->queue, rq, sg);
434         } else {
435                 sg_init_one(sg, rq->buffer, rq->nr_sectors * SECTOR_SIZE);
436                 hwif->sg_nents = 1;
437         }
438 }
439
440 EXPORT_SYMBOL_GPL(ide_map_sg);
441
442 void ide_init_sg_cmd(ide_drive_t *drive, struct request *rq)
443 {
444         ide_hwif_t *hwif = drive->hwif;
445
446         hwif->nsect = hwif->nleft = rq->nr_sectors;
447         hwif->cursg_ofs = 0;
448         hwif->cursg = NULL;
449 }
450
451 EXPORT_SYMBOL_GPL(ide_init_sg_cmd);
452
453 /**
454  *      execute_drive_command   -       issue special drive command
455  *      @drive: the drive to issue the command on
456  *      @rq: the request structure holding the command
457  *
458  *      execute_drive_cmd() issues a special drive command,  usually 
459  *      initiated by ioctl() from the external hdparm program. The
460  *      command can be a drive command, drive task or taskfile 
461  *      operation. Weirdly you can call it with NULL to wait for
462  *      all commands to finish. Don't do this as that is due to change
463  */
464
465 static ide_startstop_t execute_drive_cmd (ide_drive_t *drive,
466                 struct request *rq)
467 {
468         ide_hwif_t *hwif = HWIF(drive);
469         ide_task_t *task = rq->special;
470
471         if (task) {
472                 hwif->data_phase = task->data_phase;
473
474                 switch (hwif->data_phase) {
475                 case TASKFILE_MULTI_OUT:
476                 case TASKFILE_OUT:
477                 case TASKFILE_MULTI_IN:
478                 case TASKFILE_IN:
479                         ide_init_sg_cmd(drive, rq);
480                         ide_map_sg(drive, rq);
481                 default:
482                         break;
483                 }
484
485                 return do_rw_taskfile(drive, task);
486         }
487
488         /*
489          * NULL is actually a valid way of waiting for
490          * all current requests to be flushed from the queue.
491          */
492 #ifdef DEBUG
493         printk("%s: DRIVE_CMD (null)\n", drive->name);
494 #endif
495         ide_end_drive_cmd(drive, hwif->tp_ops->read_status(hwif),
496                           ide_read_error(drive));
497
498         return ide_stopped;
499 }
500
501 int ide_devset_execute(ide_drive_t *drive, const struct ide_devset *setting,
502                        int arg)
503 {
504         struct request_queue *q = drive->queue;
505         struct request *rq;
506         int ret = 0;
507
508         if (!(setting->flags & DS_SYNC))
509                 return setting->set(drive, arg);
510
511         rq = blk_get_request(q, READ, __GFP_WAIT);
512         rq->cmd_type = REQ_TYPE_SPECIAL;
513         rq->cmd_len = 5;
514         rq->cmd[0] = REQ_DEVSET_EXEC;
515         *(int *)&rq->cmd[1] = arg;
516         rq->special = setting->set;
517
518         if (blk_execute_rq(q, NULL, rq, 0))
519                 ret = rq->errors;
520         blk_put_request(rq);
521
522         return ret;
523 }
524 EXPORT_SYMBOL_GPL(ide_devset_execute);
525
526 static ide_startstop_t ide_special_rq(ide_drive_t *drive, struct request *rq)
527 {
528         u8 cmd = rq->cmd[0];
529
530         if (cmd == REQ_PARK_HEADS || cmd == REQ_UNPARK_HEADS) {
531                 ide_task_t task;
532                 struct ide_taskfile *tf = &task.tf;
533
534                 memset(&task, 0, sizeof(task));
535                 if (cmd == REQ_PARK_HEADS) {
536                         drive->sleep = *(unsigned long *)rq->special;
537                         drive->dev_flags |= IDE_DFLAG_SLEEPING;
538                         tf->command = ATA_CMD_IDLEIMMEDIATE;
539                         tf->feature = 0x44;
540                         tf->lbal = 0x4c;
541                         tf->lbam = 0x4e;
542                         tf->lbah = 0x55;
543                         task.tf_flags |= IDE_TFLAG_CUSTOM_HANDLER;
544                 } else          /* cmd == REQ_UNPARK_HEADS */
545                         tf->command = ATA_CMD_CHK_POWER;
546
547                 task.tf_flags |= IDE_TFLAG_TF | IDE_TFLAG_DEVICE;
548                 task.rq = rq;
549                 drive->hwif->data_phase = task.data_phase = TASKFILE_NO_DATA;
550                 return do_rw_taskfile(drive, &task);
551         }
552
553         switch (cmd) {
554         case REQ_DEVSET_EXEC:
555         {
556                 int err, (*setfunc)(ide_drive_t *, int) = rq->special;
557
558                 err = setfunc(drive, *(int *)&rq->cmd[1]);
559                 if (err)
560                         rq->errors = err;
561                 else
562                         err = 1;
563                 ide_end_request(drive, err, 0);
564                 return ide_stopped;
565         }
566         case REQ_DRIVE_RESET:
567                 return ide_do_reset(drive);
568         default:
569                 blk_dump_rq_flags(rq, "ide_special_rq - bad request");
570                 ide_end_request(drive, 0, 0);
571                 return ide_stopped;
572         }
573 }
574
575 /**
576  *      start_request   -       start of I/O and command issuing for IDE
577  *
578  *      start_request() initiates handling of a new I/O request. It
579  *      accepts commands and I/O (read/write) requests.
580  *
581  *      FIXME: this function needs a rename
582  */
583  
584 static ide_startstop_t start_request (ide_drive_t *drive, struct request *rq)
585 {
586         ide_startstop_t startstop;
587
588         BUG_ON(!blk_rq_started(rq));
589
590 #ifdef DEBUG
591         printk("%s: start_request: current=0x%08lx\n",
592                 HWIF(drive)->name, (unsigned long) rq);
593 #endif
594
595         /* bail early if we've exceeded max_failures */
596         if (drive->max_failures && (drive->failures > drive->max_failures)) {
597                 rq->cmd_flags |= REQ_FAILED;
598                 goto kill_rq;
599         }
600
601         if (blk_pm_request(rq))
602                 ide_check_pm_state(drive, rq);
603
604         SELECT_DRIVE(drive);
605         if (ide_wait_stat(&startstop, drive, drive->ready_stat,
606                           ATA_BUSY | ATA_DRQ, WAIT_READY)) {
607                 printk(KERN_ERR "%s: drive not ready for command\n", drive->name);
608                 return startstop;
609         }
610         if (!drive->special.all) {
611                 ide_driver_t *drv;
612
613                 /*
614                  * We reset the drive so we need to issue a SETFEATURES.
615                  * Do it _after_ do_special() restored device parameters.
616                  */
617                 if (drive->current_speed == 0xff)
618                         ide_config_drive_speed(drive, drive->desired_speed);
619
620                 if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE)
621                         return execute_drive_cmd(drive, rq);
622                 else if (blk_pm_request(rq)) {
623                         struct request_pm_state *pm = rq->data;
624 #ifdef DEBUG_PM
625                         printk("%s: start_power_step(step: %d)\n",
626                                 drive->name, pm->pm_step);
627 #endif
628                         startstop = ide_start_power_step(drive, rq);
629                         if (startstop == ide_stopped &&
630                             pm->pm_step == IDE_PM_COMPLETED)
631                                 ide_complete_pm_request(drive, rq);
632                         return startstop;
633                 } else if (!rq->rq_disk && blk_special_request(rq))
634                         /*
635                          * TODO: Once all ULDs have been modified to
636                          * check for specific op codes rather than
637                          * blindly accepting any special request, the
638                          * check for ->rq_disk above may be replaced
639                          * by a more suitable mechanism or even
640                          * dropped entirely.
641                          */
642                         return ide_special_rq(drive, rq);
643
644                 drv = *(ide_driver_t **)rq->rq_disk->private_data;
645
646                 return drv->do_request(drive, rq, rq->sector);
647         }
648         return do_special(drive);
649 kill_rq:
650         ide_kill_rq(drive, rq);
651         return ide_stopped;
652 }
653
654 /**
655  *      ide_stall_queue         -       pause an IDE device
656  *      @drive: drive to stall
657  *      @timeout: time to stall for (jiffies)
658  *
659  *      ide_stall_queue() can be used by a drive to give excess bandwidth back
660  *      to the hwgroup by sleeping for timeout jiffies.
661  */
662  
663 void ide_stall_queue (ide_drive_t *drive, unsigned long timeout)
664 {
665         if (timeout > WAIT_WORSTCASE)
666                 timeout = WAIT_WORSTCASE;
667         drive->sleep = timeout + jiffies;
668         drive->dev_flags |= IDE_DFLAG_SLEEPING;
669 }
670
671 EXPORT_SYMBOL(ide_stall_queue);
672
673 #define WAKEUP(drive)   ((drive)->service_start + 2 * (drive)->service_time)
674
675 /**
676  *      choose_drive            -       select a drive to service
677  *      @hwgroup: hardware group to select on
678  *
679  *      choose_drive() selects the next drive which will be serviced.
680  *      This is necessary because the IDE layer can't issue commands
681  *      to both drives on the same cable, unlike SCSI.
682  */
683  
684 static inline ide_drive_t *choose_drive (ide_hwgroup_t *hwgroup)
685 {
686         ide_drive_t *drive, *best;
687
688 repeat: 
689         best = NULL;
690         drive = hwgroup->drive;
691
692         /*
693          * drive is doing pre-flush, ordered write, post-flush sequence. even
694          * though that is 3 requests, it must be seen as a single transaction.
695          * we must not preempt this drive until that is complete
696          */
697         if (blk_queue_flushing(drive->queue)) {
698                 /*
699                  * small race where queue could get replugged during
700                  * the 3-request flush cycle, just yank the plug since
701                  * we want it to finish asap
702                  */
703                 blk_remove_plug(drive->queue);
704                 return drive;
705         }
706
707         do {
708                 u8 dev_s = !!(drive->dev_flags & IDE_DFLAG_SLEEPING);
709                 u8 best_s = (best && !!(best->dev_flags & IDE_DFLAG_SLEEPING));
710
711                 if ((dev_s == 0 || time_after_eq(jiffies, drive->sleep)) &&
712                     !elv_queue_empty(drive->queue)) {
713                         if (best == NULL ||
714                             (dev_s && (best_s == 0 || time_before(drive->sleep, best->sleep))) ||
715                             (best_s == 0 && time_before(WAKEUP(drive), WAKEUP(best)))) {
716                                 if (!blk_queue_plugged(drive->queue))
717                                         best = drive;
718                         }
719                 }
720         } while ((drive = drive->next) != hwgroup->drive);
721
722         if (best && (best->dev_flags & IDE_DFLAG_NICE1) &&
723             (best->dev_flags & IDE_DFLAG_SLEEPING) == 0 &&
724             best != hwgroup->drive && best->service_time > WAIT_MIN_SLEEP) {
725                 long t = (signed long)(WAKEUP(best) - jiffies);
726                 if (t >= WAIT_MIN_SLEEP) {
727                 /*
728                  * We *may* have some time to spare, but first let's see if
729                  * someone can potentially benefit from our nice mood today..
730                  */
731                         drive = best->next;
732                         do {
733                                 if ((drive->dev_flags & IDE_DFLAG_SLEEPING) == 0
734                                  && time_before(jiffies - best->service_time, WAKEUP(drive))
735                                  && time_before(WAKEUP(drive), jiffies + t))
736                                 {
737                                         ide_stall_queue(best, min_t(long, t, 10 * WAIT_MIN_SLEEP));
738                                         goto repeat;
739                                 }
740                         } while ((drive = drive->next) != best);
741                 }
742         }
743         return best;
744 }
745
746 /*
747  * Issue a new request to a drive from hwgroup
748  * Caller must have already done spin_lock_irqsave(&hwgroup->lock, ..);
749  *
750  * A hwgroup is a serialized group of IDE interfaces.  Usually there is
751  * exactly one hwif (interface) per hwgroup, but buggy controllers (eg. CMD640)
752  * may have both interfaces in a single hwgroup to "serialize" access.
753  * Or possibly multiple ISA interfaces can share a common IRQ by being grouped
754  * together into one hwgroup for serialized access.
755  *
756  * Note also that several hwgroups can end up sharing a single IRQ,
757  * possibly along with many other devices.  This is especially common in
758  * PCI-based systems with off-board IDE controller cards.
759  *
760  * The IDE driver uses a per-hwgroup spinlock to protect
761  * access to the request queues, and to protect the hwgroup->busy flag.
762  *
763  * The first thread into the driver for a particular hwgroup sets the
764  * hwgroup->busy flag to indicate that this hwgroup is now active,
765  * and then initiates processing of the top request from the request queue.
766  *
767  * Other threads attempting entry notice the busy setting, and will simply
768  * queue their new requests and exit immediately.  Note that hwgroup->busy
769  * remains set even when the driver is merely awaiting the next interrupt.
770  * Thus, the meaning is "this hwgroup is busy processing a request".
771  *
772  * When processing of a request completes, the completing thread or IRQ-handler
773  * will start the next request from the queue.  If no more work remains,
774  * the driver will clear the hwgroup->busy flag and exit.
775  *
776  * The per-hwgroup spinlock is used to protect all access to the
777  * hwgroup->busy flag, but is otherwise not needed for most processing in
778  * the driver.  This makes the driver much more friendlier to shared IRQs
779  * than previous designs, while remaining 100% (?) SMP safe and capable.
780  */
781 static void ide_do_request (ide_hwgroup_t *hwgroup, int masked_irq)
782 {
783         ide_drive_t     *drive;
784         ide_hwif_t      *hwif;
785         struct request  *rq;
786         ide_startstop_t startstop;
787         int             loops = 0;
788
789         /* caller must own hwgroup->lock */
790         BUG_ON(!irqs_disabled());
791
792         while (!hwgroup->busy) {
793                 hwgroup->busy = 1;
794                 /* for atari only */
795                 ide_get_lock(ide_intr, hwgroup);
796                 drive = choose_drive(hwgroup);
797                 if (drive == NULL) {
798                         int sleeping = 0;
799                         unsigned long sleep = 0; /* shut up, gcc */
800                         hwgroup->rq = NULL;
801                         drive = hwgroup->drive;
802                         do {
803                                 if ((drive->dev_flags & IDE_DFLAG_SLEEPING) &&
804                                     (sleeping == 0 ||
805                                      time_before(drive->sleep, sleep))) {
806                                         sleeping = 1;
807                                         sleep = drive->sleep;
808                                 }
809                         } while ((drive = drive->next) != hwgroup->drive);
810                         if (sleeping) {
811                 /*
812                  * Take a short snooze, and then wake up this hwgroup again.
813                  * This gives other hwgroups on the same a chance to
814                  * play fairly with us, just in case there are big differences
815                  * in relative throughputs.. don't want to hog the cpu too much.
816                  */
817                                 if (time_before(sleep, jiffies + WAIT_MIN_SLEEP))
818                                         sleep = jiffies + WAIT_MIN_SLEEP;
819 #if 1
820                                 if (timer_pending(&hwgroup->timer))
821                                         printk(KERN_CRIT "ide_set_handler: timer already active\n");
822 #endif
823                                 /* so that ide_timer_expiry knows what to do */
824                                 hwgroup->sleeping = 1;
825                                 hwgroup->req_gen_timer = hwgroup->req_gen;
826                                 mod_timer(&hwgroup->timer, sleep);
827                                 /* we purposely leave hwgroup->busy==1
828                                  * while sleeping */
829                         } else {
830                                 /* Ugly, but how can we sleep for the lock
831                                  * otherwise? perhaps from tq_disk?
832                                  */
833
834                                 /* for atari only */
835                                 ide_release_lock();
836                                 hwgroup->busy = 0;
837                         }
838
839                         /* no more work for this hwgroup (for now) */
840                         return;
841                 }
842         again:
843                 hwif = HWIF(drive);
844                 if (hwif != hwgroup->hwif) {
845                         /*
846                          * set nIEN for previous hwif, drives in the
847                          * quirk_list may not like intr setups/cleanups
848                          */
849                         if (drive->quirk_list == 0)
850                                 hwif->tp_ops->set_irq(hwif, 0);
851                 }
852                 hwgroup->hwif = hwif;
853                 hwgroup->drive = drive;
854                 drive->dev_flags &= ~(IDE_DFLAG_SLEEPING | IDE_DFLAG_PARKED);
855                 drive->service_start = jiffies;
856
857                 /*
858                  * we know that the queue isn't empty, but this can happen
859                  * if the q->prep_rq_fn() decides to kill a request
860                  */
861                 rq = elv_next_request(drive->queue);
862                 if (!rq) {
863                         hwgroup->busy = 0;
864                         break;
865                 }
866
867                 /*
868                  * Sanity: don't accept a request that isn't a PM request
869                  * if we are currently power managed. This is very important as
870                  * blk_stop_queue() doesn't prevent the elv_next_request()
871                  * above to return us whatever is in the queue. Since we call
872                  * ide_do_request() ourselves, we end up taking requests while
873                  * the queue is blocked...
874                  * 
875                  * We let requests forced at head of queue with ide-preempt
876                  * though. I hope that doesn't happen too much, hopefully not
877                  * unless the subdriver triggers such a thing in its own PM
878                  * state machine.
879                  *
880                  * We count how many times we loop here to make sure we service
881                  * all drives in the hwgroup without looping for ever
882                  */
883                 if ((drive->dev_flags & IDE_DFLAG_BLOCKED) &&
884                     blk_pm_request(rq) == 0 &&
885                     (rq->cmd_flags & REQ_PREEMPT) == 0) {
886                         drive = drive->next ? drive->next : hwgroup->drive;
887                         if (loops++ < 4 && !blk_queue_plugged(drive->queue))
888                                 goto again;
889                         /* We clear busy, there should be no pending ATA command at this point. */
890                         hwgroup->busy = 0;
891                         break;
892                 }
893
894                 hwgroup->rq = rq;
895
896                 /*
897                  * Some systems have trouble with IDE IRQs arriving while
898                  * the driver is still setting things up.  So, here we disable
899                  * the IRQ used by this interface while the request is being started.
900                  * This may look bad at first, but pretty much the same thing
901                  * happens anyway when any interrupt comes in, IDE or otherwise
902                  *  -- the kernel masks the IRQ while it is being handled.
903                  */
904                 if (masked_irq != IDE_NO_IRQ && hwif->irq != masked_irq)
905                         disable_irq_nosync(hwif->irq);
906                 spin_unlock(&hwgroup->lock);
907                 local_irq_enable_in_hardirq();
908                         /* allow other IRQs while we start this request */
909                 startstop = start_request(drive, rq);
910                 spin_lock_irq(&hwgroup->lock);
911                 if (masked_irq != IDE_NO_IRQ && hwif->irq != masked_irq)
912                         enable_irq(hwif->irq);
913                 if (startstop == ide_stopped)
914                         hwgroup->busy = 0;
915         }
916 }
917
918 /*
919  * Passes the stuff to ide_do_request
920  */
921 void do_ide_request(struct request_queue *q)
922 {
923         ide_drive_t *drive = q->queuedata;
924
925         ide_do_request(HWGROUP(drive), IDE_NO_IRQ);
926 }
927
928 /*
929  * un-busy the hwgroup etc, and clear any pending DMA status. we want to
930  * retry the current request in pio mode instead of risking tossing it
931  * all away
932  */
933 static ide_startstop_t ide_dma_timeout_retry(ide_drive_t *drive, int error)
934 {
935         ide_hwif_t *hwif = HWIF(drive);
936         struct request *rq;
937         ide_startstop_t ret = ide_stopped;
938
939         /*
940          * end current dma transaction
941          */
942
943         if (error < 0) {
944                 printk(KERN_WARNING "%s: DMA timeout error\n", drive->name);
945                 (void)hwif->dma_ops->dma_end(drive);
946                 ret = ide_error(drive, "dma timeout error",
947                                 hwif->tp_ops->read_status(hwif));
948         } else {
949                 printk(KERN_WARNING "%s: DMA timeout retry\n", drive->name);
950                 hwif->dma_ops->dma_timeout(drive);
951         }
952
953         /*
954          * disable dma for now, but remember that we did so because of
955          * a timeout -- we'll reenable after we finish this next request
956          * (or rather the first chunk of it) in pio.
957          */
958         drive->dev_flags |= IDE_DFLAG_DMA_PIO_RETRY;
959         drive->retry_pio++;
960         ide_dma_off_quietly(drive);
961
962         /*
963          * un-busy drive etc (hwgroup->busy is cleared on return) and
964          * make sure request is sane
965          */
966         rq = HWGROUP(drive)->rq;
967
968         if (!rq)
969                 goto out;
970
971         HWGROUP(drive)->rq = NULL;
972
973         rq->errors = 0;
974
975         if (!rq->bio)
976                 goto out;
977
978         rq->sector = rq->bio->bi_sector;
979         rq->current_nr_sectors = bio_iovec(rq->bio)->bv_len >> 9;
980         rq->hard_cur_sectors = rq->current_nr_sectors;
981         rq->buffer = bio_data(rq->bio);
982 out:
983         return ret;
984 }
985
986 /**
987  *      ide_timer_expiry        -       handle lack of an IDE interrupt
988  *      @data: timer callback magic (hwgroup)
989  *
990  *      An IDE command has timed out before the expected drive return
991  *      occurred. At this point we attempt to clean up the current
992  *      mess. If the current handler includes an expiry handler then
993  *      we invoke the expiry handler, and providing it is happy the
994  *      work is done. If that fails we apply generic recovery rules
995  *      invoking the handler and checking the drive DMA status. We
996  *      have an excessively incestuous relationship with the DMA
997  *      logic that wants cleaning up.
998  */
999  
1000 void ide_timer_expiry (unsigned long data)
1001 {
1002         ide_hwgroup_t   *hwgroup = (ide_hwgroup_t *) data;
1003         ide_handler_t   *handler;
1004         ide_expiry_t    *expiry;
1005         unsigned long   flags;
1006         unsigned long   wait = -1;
1007
1008         spin_lock_irqsave(&hwgroup->lock, flags);
1009
1010         if (((handler = hwgroup->handler) == NULL) ||
1011             (hwgroup->req_gen != hwgroup->req_gen_timer)) {
1012                 /*
1013                  * Either a marginal timeout occurred
1014                  * (got the interrupt just as timer expired),
1015                  * or we were "sleeping" to give other devices a chance.
1016                  * Either way, we don't really want to complain about anything.
1017                  */
1018                 if (hwgroup->sleeping) {
1019                         hwgroup->sleeping = 0;
1020                         hwgroup->busy = 0;
1021                 }
1022         } else {
1023                 ide_drive_t *drive = hwgroup->drive;
1024                 if (!drive) {
1025                         printk(KERN_ERR "ide_timer_expiry: hwgroup->drive was NULL\n");
1026                         hwgroup->handler = NULL;
1027                 } else {
1028                         ide_hwif_t *hwif;
1029                         ide_startstop_t startstop = ide_stopped;
1030                         if (!hwgroup->busy) {
1031                                 hwgroup->busy = 1;      /* paranoia */
1032                                 printk(KERN_ERR "%s: ide_timer_expiry: hwgroup->busy was 0 ??\n", drive->name);
1033                         }
1034                         if ((expiry = hwgroup->expiry) != NULL) {
1035                                 /* continue */
1036                                 if ((wait = expiry(drive)) > 0) {
1037                                         /* reset timer */
1038                                         hwgroup->timer.expires  = jiffies + wait;
1039                                         hwgroup->req_gen_timer = hwgroup->req_gen;
1040                                         add_timer(&hwgroup->timer);
1041                                         spin_unlock_irqrestore(&hwgroup->lock, flags);
1042                                         return;
1043                                 }
1044                         }
1045                         hwgroup->handler = NULL;
1046                         /*
1047                          * We need to simulate a real interrupt when invoking
1048                          * the handler() function, which means we need to
1049                          * globally mask the specific IRQ:
1050                          */
1051                         spin_unlock(&hwgroup->lock);
1052                         hwif  = HWIF(drive);
1053                         /* disable_irq_nosync ?? */
1054                         disable_irq(hwif->irq);
1055                         /* local CPU only,
1056                          * as if we were handling an interrupt */
1057                         local_irq_disable();
1058                         if (hwgroup->polling) {
1059                                 startstop = handler(drive);
1060                         } else if (drive_is_ready(drive)) {
1061                                 if (drive->waiting_for_dma)
1062                                         hwif->dma_ops->dma_lost_irq(drive);
1063                                 (void)ide_ack_intr(hwif);
1064                                 printk(KERN_WARNING "%s: lost interrupt\n", drive->name);
1065                                 startstop = handler(drive);
1066                         } else {
1067                                 if (drive->waiting_for_dma) {
1068                                         startstop = ide_dma_timeout_retry(drive, wait);
1069                                 } else
1070                                         startstop =
1071                                         ide_error(drive, "irq timeout",
1072                                                   hwif->tp_ops->read_status(hwif));
1073                         }
1074                         drive->service_time = jiffies - drive->service_start;
1075                         spin_lock_irq(&hwgroup->lock);
1076                         enable_irq(hwif->irq);
1077                         if (startstop == ide_stopped)
1078                                 hwgroup->busy = 0;
1079                 }
1080         }
1081         ide_do_request(hwgroup, IDE_NO_IRQ);
1082         spin_unlock_irqrestore(&hwgroup->lock, flags);
1083 }
1084
1085 /**
1086  *      unexpected_intr         -       handle an unexpected IDE interrupt
1087  *      @irq: interrupt line
1088  *      @hwgroup: hwgroup being processed
1089  *
1090  *      There's nothing really useful we can do with an unexpected interrupt,
1091  *      other than reading the status register (to clear it), and logging it.
1092  *      There should be no way that an irq can happen before we're ready for it,
1093  *      so we needn't worry much about losing an "important" interrupt here.
1094  *
1095  *      On laptops (and "green" PCs), an unexpected interrupt occurs whenever
1096  *      the drive enters "idle", "standby", or "sleep" mode, so if the status
1097  *      looks "good", we just ignore the interrupt completely.
1098  *
1099  *      This routine assumes __cli() is in effect when called.
1100  *
1101  *      If an unexpected interrupt happens on irq15 while we are handling irq14
1102  *      and if the two interfaces are "serialized" (CMD640), then it looks like
1103  *      we could screw up by interfering with a new request being set up for 
1104  *      irq15.
1105  *
1106  *      In reality, this is a non-issue.  The new command is not sent unless 
1107  *      the drive is ready to accept one, in which case we know the drive is
1108  *      not trying to interrupt us.  And ide_set_handler() is always invoked
1109  *      before completing the issuance of any new drive command, so we will not
1110  *      be accidentally invoked as a result of any valid command completion
1111  *      interrupt.
1112  *
1113  *      Note that we must walk the entire hwgroup here. We know which hwif
1114  *      is doing the current command, but we don't know which hwif burped
1115  *      mysteriously.
1116  */
1117  
1118 static void unexpected_intr (int irq, ide_hwgroup_t *hwgroup)
1119 {
1120         u8 stat;
1121         ide_hwif_t *hwif = hwgroup->hwif;
1122
1123         /*
1124          * handle the unexpected interrupt
1125          */
1126         do {
1127                 if (hwif->irq == irq) {
1128                         stat = hwif->tp_ops->read_status(hwif);
1129
1130                         if (!OK_STAT(stat, ATA_DRDY, BAD_STAT)) {
1131                                 /* Try to not flood the console with msgs */
1132                                 static unsigned long last_msgtime, count;
1133                                 ++count;
1134                                 if (time_after(jiffies, last_msgtime + HZ)) {
1135                                         last_msgtime = jiffies;
1136                                         printk(KERN_ERR "%s%s: unexpected interrupt, "
1137                                                 "status=0x%02x, count=%ld\n",
1138                                                 hwif->name,
1139                                                 (hwif->next==hwgroup->hwif) ? "" : "(?)", stat, count);
1140                                 }
1141                         }
1142                 }
1143         } while ((hwif = hwif->next) != hwgroup->hwif);
1144 }
1145
1146 /**
1147  *      ide_intr        -       default IDE interrupt handler
1148  *      @irq: interrupt number
1149  *      @dev_id: hwif group
1150  *      @regs: unused weirdness from the kernel irq layer
1151  *
1152  *      This is the default IRQ handler for the IDE layer. You should
1153  *      not need to override it. If you do be aware it is subtle in
1154  *      places
1155  *
1156  *      hwgroup->hwif is the interface in the group currently performing
1157  *      a command. hwgroup->drive is the drive and hwgroup->handler is
1158  *      the IRQ handler to call. As we issue a command the handlers
1159  *      step through multiple states, reassigning the handler to the
1160  *      next step in the process. Unlike a smart SCSI controller IDE
1161  *      expects the main processor to sequence the various transfer
1162  *      stages. We also manage a poll timer to catch up with most
1163  *      timeout situations. There are still a few where the handlers
1164  *      don't ever decide to give up.
1165  *
1166  *      The handler eventually returns ide_stopped to indicate the
1167  *      request completed. At this point we issue the next request
1168  *      on the hwgroup and the process begins again.
1169  */
1170  
1171 irqreturn_t ide_intr (int irq, void *dev_id)
1172 {
1173         unsigned long flags;
1174         ide_hwgroup_t *hwgroup = (ide_hwgroup_t *)dev_id;
1175         ide_hwif_t *hwif = hwgroup->hwif;
1176         ide_drive_t *drive;
1177         ide_handler_t *handler;
1178         ide_startstop_t startstop;
1179         irqreturn_t irq_ret = IRQ_NONE;
1180
1181         spin_lock_irqsave(&hwgroup->lock, flags);
1182
1183         if (!ide_ack_intr(hwif))
1184                 goto out;
1185
1186         if ((handler = hwgroup->handler) == NULL || hwgroup->polling) {
1187                 /*
1188                  * Not expecting an interrupt from this drive.
1189                  * That means this could be:
1190                  *      (1) an interrupt from another PCI device
1191                  *      sharing the same PCI INT# as us.
1192                  * or   (2) a drive just entered sleep or standby mode,
1193                  *      and is interrupting to let us know.
1194                  * or   (3) a spurious interrupt of unknown origin.
1195                  *
1196                  * For PCI, we cannot tell the difference,
1197                  * so in that case we just ignore it and hope it goes away.
1198                  *
1199                  * FIXME: unexpected_intr should be hwif-> then we can
1200                  * remove all the ifdef PCI crap
1201                  */
1202 #ifdef CONFIG_BLK_DEV_IDEPCI
1203                 if (hwif->chipset != ide_pci)
1204 #endif  /* CONFIG_BLK_DEV_IDEPCI */
1205                 {
1206                         /*
1207                          * Probably not a shared PCI interrupt,
1208                          * so we can safely try to do something about it:
1209                          */
1210                         unexpected_intr(irq, hwgroup);
1211 #ifdef CONFIG_BLK_DEV_IDEPCI
1212                 } else {
1213                         /*
1214                          * Whack the status register, just in case
1215                          * we have a leftover pending IRQ.
1216                          */
1217                         (void)hwif->tp_ops->read_status(hwif);
1218 #endif /* CONFIG_BLK_DEV_IDEPCI */
1219                 }
1220                 goto out;
1221         }
1222
1223         drive = hwgroup->drive;
1224         if (!drive) {
1225                 /*
1226                  * This should NEVER happen, and there isn't much
1227                  * we could do about it here.
1228                  *
1229                  * [Note - this can occur if the drive is hot unplugged]
1230                  */
1231                 goto out_handled;
1232         }
1233
1234         if (!drive_is_ready(drive))
1235                 /*
1236                  * This happens regularly when we share a PCI IRQ with
1237                  * another device.  Unfortunately, it can also happen
1238                  * with some buggy drives that trigger the IRQ before
1239                  * their status register is up to date.  Hopefully we have
1240                  * enough advance overhead that the latter isn't a problem.
1241                  */
1242                 goto out;
1243
1244         if (!hwgroup->busy) {
1245                 hwgroup->busy = 1;      /* paranoia */
1246                 printk(KERN_ERR "%s: ide_intr: hwgroup->busy was 0 ??\n", drive->name);
1247         }
1248         hwgroup->handler = NULL;
1249         hwgroup->req_gen++;
1250         del_timer(&hwgroup->timer);
1251         spin_unlock(&hwgroup->lock);
1252
1253         if (hwif->port_ops && hwif->port_ops->clear_irq)
1254                 hwif->port_ops->clear_irq(drive);
1255
1256         if (drive->dev_flags & IDE_DFLAG_UNMASK)
1257                 local_irq_enable_in_hardirq();
1258
1259         /* service this interrupt, may set handler for next interrupt */
1260         startstop = handler(drive);
1261
1262         spin_lock_irq(&hwgroup->lock);
1263         /*
1264          * Note that handler() may have set things up for another
1265          * interrupt to occur soon, but it cannot happen until
1266          * we exit from this routine, because it will be the
1267          * same irq as is currently being serviced here, and Linux
1268          * won't allow another of the same (on any CPU) until we return.
1269          */
1270         drive->service_time = jiffies - drive->service_start;
1271         if (startstop == ide_stopped) {
1272                 if (hwgroup->handler == NULL) { /* paranoia */
1273                         hwgroup->busy = 0;
1274                         ide_do_request(hwgroup, hwif->irq);
1275                 } else {
1276                         printk(KERN_ERR "%s: ide_intr: huh? expected NULL handler "
1277                                 "on exit\n", drive->name);
1278                 }
1279         }
1280 out_handled:
1281         irq_ret = IRQ_HANDLED;
1282 out:
1283         spin_unlock_irqrestore(&hwgroup->lock, flags);
1284         return irq_ret;
1285 }
1286
1287 /**
1288  *      ide_do_drive_cmd        -       issue IDE special command
1289  *      @drive: device to issue command
1290  *      @rq: request to issue
1291  *
1292  *      This function issues a special IDE device request
1293  *      onto the request queue.
1294  *
1295  *      the rq is queued at the head of the request queue, displacing
1296  *      the currently-being-processed request and this function
1297  *      returns immediately without waiting for the new rq to be
1298  *      completed.  This is VERY DANGEROUS, and is intended for
1299  *      careful use by the ATAPI tape/cdrom driver code.
1300  */
1301
1302 void ide_do_drive_cmd(ide_drive_t *drive, struct request *rq)
1303 {
1304         ide_hwgroup_t *hwgroup = drive->hwif->hwgroup;
1305         struct request_queue *q = drive->queue;
1306         unsigned long flags;
1307
1308         hwgroup->rq = NULL;
1309
1310         spin_lock_irqsave(q->queue_lock, flags);
1311         __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
1312         blk_start_queueing(q);
1313         spin_unlock_irqrestore(q->queue_lock, flags);
1314 }
1315 EXPORT_SYMBOL(ide_do_drive_cmd);
1316
1317 void ide_pktcmd_tf_load(ide_drive_t *drive, u32 tf_flags, u16 bcount, u8 dma)
1318 {
1319         ide_hwif_t *hwif = drive->hwif;
1320         ide_task_t task;
1321
1322         memset(&task, 0, sizeof(task));
1323         task.tf_flags = IDE_TFLAG_OUT_LBAH | IDE_TFLAG_OUT_LBAM |
1324                         IDE_TFLAG_OUT_FEATURE | tf_flags;
1325         task.tf.feature = dma;          /* Use PIO/DMA */
1326         task.tf.lbam    = bcount & 0xff;
1327         task.tf.lbah    = (bcount >> 8) & 0xff;
1328
1329         ide_tf_dump(drive->name, &task.tf);
1330         hwif->tp_ops->set_irq(hwif, 1);
1331         SELECT_MASK(drive, 0);
1332         hwif->tp_ops->tf_load(drive, &task);
1333 }
1334
1335 EXPORT_SYMBOL_GPL(ide_pktcmd_tf_load);
1336
1337 void ide_pad_transfer(ide_drive_t *drive, int write, int len)
1338 {
1339         ide_hwif_t *hwif = drive->hwif;
1340         u8 buf[4] = { 0 };
1341
1342         while (len > 0) {
1343                 if (write)
1344                         hwif->tp_ops->output_data(drive, NULL, buf, min(4, len));
1345                 else
1346                         hwif->tp_ops->input_data(drive, NULL, buf, min(4, len));
1347                 len -= 4;
1348         }
1349 }
1350 EXPORT_SYMBOL_GPL(ide_pad_transfer);