block: implement blk_rq_pos/[cur_]sectors() and convert obvious ones
[linux-2.6.git] / 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/completion.h>
44 #include <linux/reboot.h>
45 #include <linux/cdrom.h>
46 #include <linux/seq_file.h>
47 #include <linux/device.h>
48 #include <linux/kmod.h>
49 #include <linux/scatterlist.h>
50 #include <linux/bitops.h>
51
52 #include <asm/byteorder.h>
53 #include <asm/irq.h>
54 #include <asm/uaccess.h>
55 #include <asm/io.h>
56
57 int ide_end_rq(ide_drive_t *drive, struct request *rq, int error,
58                unsigned int nr_bytes)
59 {
60         /*
61          * decide whether to reenable DMA -- 3 is a random magic for now,
62          * if we DMA timeout more than 3 times, just stay in PIO
63          */
64         if ((drive->dev_flags & IDE_DFLAG_DMA_PIO_RETRY) &&
65             drive->retry_pio <= 3) {
66                 drive->dev_flags &= ~IDE_DFLAG_DMA_PIO_RETRY;
67                 ide_dma_on(drive);
68         }
69
70         return blk_end_request(rq, error, nr_bytes);
71 }
72 EXPORT_SYMBOL_GPL(ide_end_rq);
73
74 void ide_complete_cmd(ide_drive_t *drive, struct ide_cmd *cmd, u8 stat, u8 err)
75 {
76         const struct ide_tp_ops *tp_ops = drive->hwif->tp_ops;
77         struct ide_taskfile *tf = &cmd->tf;
78         struct request *rq = cmd->rq;
79         u8 tf_cmd = tf->command;
80
81         tf->error = err;
82         tf->status = stat;
83
84         if (cmd->ftf_flags & IDE_FTFLAG_IN_DATA) {
85                 u8 data[2];
86
87                 tp_ops->input_data(drive, cmd, data, 2);
88
89                 cmd->tf.data  = data[0];
90                 cmd->hob.data = data[1];
91         }
92
93         ide_tf_readback(drive, cmd);
94
95         if ((cmd->tf_flags & IDE_TFLAG_CUSTOM_HANDLER) &&
96             tf_cmd == ATA_CMD_IDLEIMMEDIATE) {
97                 if (tf->lbal != 0xc4) {
98                         printk(KERN_ERR "%s: head unload failed!\n",
99                                drive->name);
100                         ide_tf_dump(drive->name, cmd);
101                 } else
102                         drive->dev_flags |= IDE_DFLAG_PARKED;
103         }
104
105         if (rq && rq->cmd_type == REQ_TYPE_ATA_TASKFILE) {
106                 struct ide_cmd *orig_cmd = rq->special;
107
108                 if (cmd->tf_flags & IDE_TFLAG_DYN)
109                         kfree(orig_cmd);
110                 else
111                         memcpy(orig_cmd, cmd, sizeof(*cmd));
112         }
113 }
114
115 /* obsolete, blk_rq_bytes() should be used instead */
116 unsigned int ide_rq_bytes(struct request *rq)
117 {
118         if (blk_pc_request(rq))
119                 return rq->data_len;
120         else
121                 return blk_rq_cur_sectors(rq) << 9;
122 }
123 EXPORT_SYMBOL_GPL(ide_rq_bytes);
124
125 int ide_complete_rq(ide_drive_t *drive, int error, unsigned int nr_bytes)
126 {
127         ide_hwif_t *hwif = drive->hwif;
128         struct request *rq = hwif->rq;
129         int rc;
130
131         /*
132          * if failfast is set on a request, override number of sectors
133          * and complete the whole request right now
134          */
135         if (blk_noretry_request(rq) && error <= 0)
136                 nr_bytes = blk_rq_sectors(rq) << 9;
137
138         rc = ide_end_rq(drive, rq, error, nr_bytes);
139         if (rc == 0)
140                 hwif->rq = NULL;
141
142         return rc;
143 }
144 EXPORT_SYMBOL(ide_complete_rq);
145
146 void ide_kill_rq(ide_drive_t *drive, struct request *rq)
147 {
148         u8 drv_req = blk_special_request(rq) && rq->rq_disk;
149         u8 media = drive->media;
150
151         drive->failed_pc = NULL;
152
153         if ((media == ide_floppy || media == ide_tape) && drv_req) {
154                 rq->errors = 0;
155                 ide_complete_rq(drive, 0, blk_rq_bytes(rq));
156         } else {
157                 if (media == ide_tape)
158                         rq->errors = IDE_DRV_ERROR_GENERAL;
159                 else if (blk_fs_request(rq) == 0 && rq->errors == 0)
160                         rq->errors = -EIO;
161                 ide_complete_rq(drive, -EIO, ide_rq_bytes(rq));
162         }
163 }
164
165 static void ide_tf_set_specify_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
166 {
167         tf->nsect   = drive->sect;
168         tf->lbal    = drive->sect;
169         tf->lbam    = drive->cyl;
170         tf->lbah    = drive->cyl >> 8;
171         tf->device  = (drive->head - 1) | drive->select;
172         tf->command = ATA_CMD_INIT_DEV_PARAMS;
173 }
174
175 static void ide_tf_set_restore_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
176 {
177         tf->nsect   = drive->sect;
178         tf->command = ATA_CMD_RESTORE;
179 }
180
181 static void ide_tf_set_setmult_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
182 {
183         tf->nsect   = drive->mult_req;
184         tf->command = ATA_CMD_SET_MULTI;
185 }
186
187 static ide_startstop_t ide_disk_special(ide_drive_t *drive)
188 {
189         special_t *s = &drive->special;
190         struct ide_cmd cmd;
191
192         memset(&cmd, 0, sizeof(cmd));
193         cmd.protocol = ATA_PROT_NODATA;
194
195         if (s->b.set_geometry) {
196                 s->b.set_geometry = 0;
197                 ide_tf_set_specify_cmd(drive, &cmd.tf);
198         } else if (s->b.recalibrate) {
199                 s->b.recalibrate = 0;
200                 ide_tf_set_restore_cmd(drive, &cmd.tf);
201         } else if (s->b.set_multmode) {
202                 s->b.set_multmode = 0;
203                 ide_tf_set_setmult_cmd(drive, &cmd.tf);
204         } else if (s->all) {
205                 int special = s->all;
206                 s->all = 0;
207                 printk(KERN_ERR "%s: bad special flag: 0x%02x\n", drive->name, special);
208                 return ide_stopped;
209         }
210
211         cmd.valid.out.tf = IDE_VALID_OUT_TF | IDE_VALID_DEVICE;
212         cmd.valid.in.tf  = IDE_VALID_IN_TF  | IDE_VALID_DEVICE;
213         cmd.tf_flags = IDE_TFLAG_CUSTOM_HANDLER;
214
215         do_rw_taskfile(drive, &cmd);
216
217         return ide_started;
218 }
219
220 /**
221  *      do_special              -       issue some special commands
222  *      @drive: drive the command is for
223  *
224  *      do_special() is used to issue ATA_CMD_INIT_DEV_PARAMS,
225  *      ATA_CMD_RESTORE and ATA_CMD_SET_MULTI commands to a drive.
226  *
227  *      It used to do much more, but has been scaled back.
228  */
229
230 static ide_startstop_t do_special (ide_drive_t *drive)
231 {
232         special_t *s = &drive->special;
233
234 #ifdef DEBUG
235         printk("%s: do_special: 0x%02x\n", drive->name, s->all);
236 #endif
237         if (drive->media == ide_disk)
238                 return ide_disk_special(drive);
239
240         s->all = 0;
241         drive->mult_req = 0;
242         return ide_stopped;
243 }
244
245 void ide_map_sg(ide_drive_t *drive, struct ide_cmd *cmd)
246 {
247         ide_hwif_t *hwif = drive->hwif;
248         struct scatterlist *sg = hwif->sg_table;
249         struct request *rq = cmd->rq;
250
251         cmd->sg_nents = blk_rq_map_sg(drive->queue, rq, sg);
252 }
253 EXPORT_SYMBOL_GPL(ide_map_sg);
254
255 void ide_init_sg_cmd(struct ide_cmd *cmd, unsigned int nr_bytes)
256 {
257         cmd->nbytes = cmd->nleft = nr_bytes;
258         cmd->cursg_ofs = 0;
259         cmd->cursg = NULL;
260 }
261 EXPORT_SYMBOL_GPL(ide_init_sg_cmd);
262
263 /**
264  *      execute_drive_command   -       issue special drive command
265  *      @drive: the drive to issue the command on
266  *      @rq: the request structure holding the command
267  *
268  *      execute_drive_cmd() issues a special drive command,  usually 
269  *      initiated by ioctl() from the external hdparm program. The
270  *      command can be a drive command, drive task or taskfile 
271  *      operation. Weirdly you can call it with NULL to wait for
272  *      all commands to finish. Don't do this as that is due to change
273  */
274
275 static ide_startstop_t execute_drive_cmd (ide_drive_t *drive,
276                 struct request *rq)
277 {
278         struct ide_cmd *cmd = rq->special;
279
280         if (cmd) {
281                 if (cmd->protocol == ATA_PROT_PIO) {
282                         ide_init_sg_cmd(cmd, rq->nr_sectors << 9);
283                         ide_map_sg(drive, cmd);
284                 }
285
286                 return do_rw_taskfile(drive, cmd);
287         }
288
289         /*
290          * NULL is actually a valid way of waiting for
291          * all current requests to be flushed from the queue.
292          */
293 #ifdef DEBUG
294         printk("%s: DRIVE_CMD (null)\n", drive->name);
295 #endif
296         rq->errors = 0;
297         ide_complete_rq(drive, 0, blk_rq_bytes(rq));
298
299         return ide_stopped;
300 }
301
302 static ide_startstop_t ide_special_rq(ide_drive_t *drive, struct request *rq)
303 {
304         u8 cmd = rq->cmd[0];
305
306         switch (cmd) {
307         case REQ_PARK_HEADS:
308         case REQ_UNPARK_HEADS:
309                 return ide_do_park_unpark(drive, rq);
310         case REQ_DEVSET_EXEC:
311                 return ide_do_devset(drive, rq);
312         case REQ_DRIVE_RESET:
313                 return ide_do_reset(drive);
314         default:
315                 BUG();
316         }
317 }
318
319 /**
320  *      start_request   -       start of I/O and command issuing for IDE
321  *
322  *      start_request() initiates handling of a new I/O request. It
323  *      accepts commands and I/O (read/write) requests.
324  *
325  *      FIXME: this function needs a rename
326  */
327  
328 static ide_startstop_t start_request (ide_drive_t *drive, struct request *rq)
329 {
330         ide_startstop_t startstop;
331
332         BUG_ON(!blk_rq_started(rq));
333
334 #ifdef DEBUG
335         printk("%s: start_request: current=0x%08lx\n",
336                 drive->hwif->name, (unsigned long) rq);
337 #endif
338
339         /* bail early if we've exceeded max_failures */
340         if (drive->max_failures && (drive->failures > drive->max_failures)) {
341                 rq->cmd_flags |= REQ_FAILED;
342                 goto kill_rq;
343         }
344
345         if (blk_pm_request(rq))
346                 ide_check_pm_state(drive, rq);
347
348         drive->hwif->tp_ops->dev_select(drive);
349         if (ide_wait_stat(&startstop, drive, drive->ready_stat,
350                           ATA_BUSY | ATA_DRQ, WAIT_READY)) {
351                 printk(KERN_ERR "%s: drive not ready for command\n", drive->name);
352                 return startstop;
353         }
354         if (!drive->special.all) {
355                 struct ide_driver *drv;
356
357                 /*
358                  * We reset the drive so we need to issue a SETFEATURES.
359                  * Do it _after_ do_special() restored device parameters.
360                  */
361                 if (drive->current_speed == 0xff)
362                         ide_config_drive_speed(drive, drive->desired_speed);
363
364                 if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE)
365                         return execute_drive_cmd(drive, rq);
366                 else if (blk_pm_request(rq)) {
367                         struct request_pm_state *pm = rq->special;
368 #ifdef DEBUG_PM
369                         printk("%s: start_power_step(step: %d)\n",
370                                 drive->name, pm->pm_step);
371 #endif
372                         startstop = ide_start_power_step(drive, rq);
373                         if (startstop == ide_stopped &&
374                             pm->pm_step == IDE_PM_COMPLETED)
375                                 ide_complete_pm_rq(drive, rq);
376                         return startstop;
377                 } else if (!rq->rq_disk && blk_special_request(rq))
378                         /*
379                          * TODO: Once all ULDs have been modified to
380                          * check for specific op codes rather than
381                          * blindly accepting any special request, the
382                          * check for ->rq_disk above may be replaced
383                          * by a more suitable mechanism or even
384                          * dropped entirely.
385                          */
386                         return ide_special_rq(drive, rq);
387
388                 drv = *(struct ide_driver **)rq->rq_disk->private_data;
389
390                 return drv->do_request(drive, rq, rq->sector);
391         }
392         return do_special(drive);
393 kill_rq:
394         ide_kill_rq(drive, rq);
395         return ide_stopped;
396 }
397
398 /**
399  *      ide_stall_queue         -       pause an IDE device
400  *      @drive: drive to stall
401  *      @timeout: time to stall for (jiffies)
402  *
403  *      ide_stall_queue() can be used by a drive to give excess bandwidth back
404  *      to the port by sleeping for timeout jiffies.
405  */
406  
407 void ide_stall_queue (ide_drive_t *drive, unsigned long timeout)
408 {
409         if (timeout > WAIT_WORSTCASE)
410                 timeout = WAIT_WORSTCASE;
411         drive->sleep = timeout + jiffies;
412         drive->dev_flags |= IDE_DFLAG_SLEEPING;
413 }
414 EXPORT_SYMBOL(ide_stall_queue);
415
416 static inline int ide_lock_port(ide_hwif_t *hwif)
417 {
418         if (hwif->busy)
419                 return 1;
420
421         hwif->busy = 1;
422
423         return 0;
424 }
425
426 static inline void ide_unlock_port(ide_hwif_t *hwif)
427 {
428         hwif->busy = 0;
429 }
430
431 static inline int ide_lock_host(struct ide_host *host, ide_hwif_t *hwif)
432 {
433         int rc = 0;
434
435         if (host->host_flags & IDE_HFLAG_SERIALIZE) {
436                 rc = test_and_set_bit_lock(IDE_HOST_BUSY, &host->host_busy);
437                 if (rc == 0) {
438                         if (host->get_lock)
439                                 host->get_lock(ide_intr, hwif);
440                 }
441         }
442         return rc;
443 }
444
445 static inline void ide_unlock_host(struct ide_host *host)
446 {
447         if (host->host_flags & IDE_HFLAG_SERIALIZE) {
448                 if (host->release_lock)
449                         host->release_lock();
450                 clear_bit_unlock(IDE_HOST_BUSY, &host->host_busy);
451         }
452 }
453
454 /*
455  * Issue a new request to a device.
456  */
457 void do_ide_request(struct request_queue *q)
458 {
459         ide_drive_t     *drive = q->queuedata;
460         ide_hwif_t      *hwif = drive->hwif;
461         struct ide_host *host = hwif->host;
462         struct request  *rq = NULL;
463         ide_startstop_t startstop;
464
465         /*
466          * drive is doing pre-flush, ordered write, post-flush sequence. even
467          * though that is 3 requests, it must be seen as a single transaction.
468          * we must not preempt this drive until that is complete
469          */
470         if (blk_queue_flushing(q))
471                 /*
472                  * small race where queue could get replugged during
473                  * the 3-request flush cycle, just yank the plug since
474                  * we want it to finish asap
475                  */
476                 blk_remove_plug(q);
477
478         spin_unlock_irq(q->queue_lock);
479
480         /* HLD do_request() callback might sleep, make sure it's okay */
481         might_sleep();
482
483         if (ide_lock_host(host, hwif))
484                 goto plug_device_2;
485
486         spin_lock_irq(&hwif->lock);
487
488         if (!ide_lock_port(hwif)) {
489                 ide_hwif_t *prev_port;
490 repeat:
491                 prev_port = hwif->host->cur_port;
492                 hwif->rq = NULL;
493
494                 if (drive->dev_flags & IDE_DFLAG_SLEEPING &&
495                     time_after(drive->sleep, jiffies)) {
496                         ide_unlock_port(hwif);
497                         goto plug_device;
498                 }
499
500                 if ((hwif->host->host_flags & IDE_HFLAG_SERIALIZE) &&
501                     hwif != prev_port) {
502                         /*
503                          * set nIEN for previous port, drives in the
504                          * quirk_list may not like intr setups/cleanups
505                          */
506                         if (prev_port && prev_port->cur_dev->quirk_list == 0)
507                                 prev_port->tp_ops->write_devctl(prev_port,
508                                                                 ATA_NIEN |
509                                                                 ATA_DEVCTL_OBS);
510
511                         hwif->host->cur_port = hwif;
512                 }
513                 hwif->cur_dev = drive;
514                 drive->dev_flags &= ~(IDE_DFLAG_SLEEPING | IDE_DFLAG_PARKED);
515
516                 spin_unlock_irq(&hwif->lock);
517                 spin_lock_irq(q->queue_lock);
518                 /*
519                  * we know that the queue isn't empty, but this can happen
520                  * if the q->prep_rq_fn() decides to kill a request
521                  */
522                 rq = elv_next_request(drive->queue);
523                 spin_unlock_irq(q->queue_lock);
524                 spin_lock_irq(&hwif->lock);
525
526                 if (!rq) {
527                         ide_unlock_port(hwif);
528                         goto out;
529                 }
530
531                 /*
532                  * Sanity: don't accept a request that isn't a PM request
533                  * if we are currently power managed. This is very important as
534                  * blk_stop_queue() doesn't prevent the elv_next_request()
535                  * above to return us whatever is in the queue. Since we call
536                  * ide_do_request() ourselves, we end up taking requests while
537                  * the queue is blocked...
538                  * 
539                  * We let requests forced at head of queue with ide-preempt
540                  * though. I hope that doesn't happen too much, hopefully not
541                  * unless the subdriver triggers such a thing in its own PM
542                  * state machine.
543                  */
544                 if ((drive->dev_flags & IDE_DFLAG_BLOCKED) &&
545                     blk_pm_request(rq) == 0 &&
546                     (rq->cmd_flags & REQ_PREEMPT) == 0) {
547                         /* there should be no pending command at this point */
548                         ide_unlock_port(hwif);
549                         goto plug_device;
550                 }
551
552                 hwif->rq = rq;
553
554                 spin_unlock_irq(&hwif->lock);
555                 startstop = start_request(drive, rq);
556                 spin_lock_irq(&hwif->lock);
557
558                 if (startstop == ide_stopped)
559                         goto repeat;
560         } else
561                 goto plug_device;
562 out:
563         spin_unlock_irq(&hwif->lock);
564         if (rq == NULL)
565                 ide_unlock_host(host);
566         spin_lock_irq(q->queue_lock);
567         return;
568
569 plug_device:
570         spin_unlock_irq(&hwif->lock);
571         ide_unlock_host(host);
572 plug_device_2:
573         spin_lock_irq(q->queue_lock);
574
575         if (!elv_queue_empty(q))
576                 blk_plug_device(q);
577 }
578
579 static void ide_plug_device(ide_drive_t *drive)
580 {
581         struct request_queue *q = drive->queue;
582         unsigned long flags;
583
584         spin_lock_irqsave(q->queue_lock, flags);
585         if (!elv_queue_empty(q))
586                 blk_plug_device(q);
587         spin_unlock_irqrestore(q->queue_lock, flags);
588 }
589
590 static int drive_is_ready(ide_drive_t *drive)
591 {
592         ide_hwif_t *hwif = drive->hwif;
593         u8 stat = 0;
594
595         if (drive->waiting_for_dma)
596                 return hwif->dma_ops->dma_test_irq(drive);
597
598         if (hwif->io_ports.ctl_addr &&
599             (hwif->host_flags & IDE_HFLAG_BROKEN_ALTSTATUS) == 0)
600                 stat = hwif->tp_ops->read_altstatus(hwif);
601         else
602                 /* Note: this may clear a pending IRQ!! */
603                 stat = hwif->tp_ops->read_status(hwif);
604
605         if (stat & ATA_BUSY)
606                 /* drive busy: definitely not interrupting */
607                 return 0;
608
609         /* drive ready: *might* be interrupting */
610         return 1;
611 }
612
613 /**
614  *      ide_timer_expiry        -       handle lack of an IDE interrupt
615  *      @data: timer callback magic (hwif)
616  *
617  *      An IDE command has timed out before the expected drive return
618  *      occurred. At this point we attempt to clean up the current
619  *      mess. If the current handler includes an expiry handler then
620  *      we invoke the expiry handler, and providing it is happy the
621  *      work is done. If that fails we apply generic recovery rules
622  *      invoking the handler and checking the drive DMA status. We
623  *      have an excessively incestuous relationship with the DMA
624  *      logic that wants cleaning up.
625  */
626  
627 void ide_timer_expiry (unsigned long data)
628 {
629         ide_hwif_t      *hwif = (ide_hwif_t *)data;
630         ide_drive_t     *uninitialized_var(drive);
631         ide_handler_t   *handler;
632         unsigned long   flags;
633         int             wait = -1;
634         int             plug_device = 0;
635
636         spin_lock_irqsave(&hwif->lock, flags);
637
638         handler = hwif->handler;
639
640         if (handler == NULL || hwif->req_gen != hwif->req_gen_timer) {
641                 /*
642                  * Either a marginal timeout occurred
643                  * (got the interrupt just as timer expired),
644                  * or we were "sleeping" to give other devices a chance.
645                  * Either way, we don't really want to complain about anything.
646                  */
647         } else {
648                 ide_expiry_t *expiry = hwif->expiry;
649                 ide_startstop_t startstop = ide_stopped;
650
651                 drive = hwif->cur_dev;
652
653                 if (expiry) {
654                         wait = expiry(drive);
655                         if (wait > 0) { /* continue */
656                                 /* reset timer */
657                                 hwif->timer.expires = jiffies + wait;
658                                 hwif->req_gen_timer = hwif->req_gen;
659                                 add_timer(&hwif->timer);
660                                 spin_unlock_irqrestore(&hwif->lock, flags);
661                                 return;
662                         }
663                 }
664                 hwif->handler = NULL;
665                 hwif->expiry = NULL;
666                 /*
667                  * We need to simulate a real interrupt when invoking
668                  * the handler() function, which means we need to
669                  * globally mask the specific IRQ:
670                  */
671                 spin_unlock(&hwif->lock);
672                 /* disable_irq_nosync ?? */
673                 disable_irq(hwif->irq);
674                 /* local CPU only, as if we were handling an interrupt */
675                 local_irq_disable();
676                 if (hwif->polling) {
677                         startstop = handler(drive);
678                 } else if (drive_is_ready(drive)) {
679                         if (drive->waiting_for_dma)
680                                 hwif->dma_ops->dma_lost_irq(drive);
681                         if (hwif->ack_intr)
682                                 hwif->ack_intr(hwif);
683                         printk(KERN_WARNING "%s: lost interrupt\n",
684                                 drive->name);
685                         startstop = handler(drive);
686                 } else {
687                         if (drive->waiting_for_dma)
688                                 startstop = ide_dma_timeout_retry(drive, wait);
689                         else
690                                 startstop = ide_error(drive, "irq timeout",
691                                         hwif->tp_ops->read_status(hwif));
692                 }
693                 spin_lock_irq(&hwif->lock);
694                 enable_irq(hwif->irq);
695                 if (startstop == ide_stopped) {
696                         ide_unlock_port(hwif);
697                         plug_device = 1;
698                 }
699         }
700         spin_unlock_irqrestore(&hwif->lock, flags);
701
702         if (plug_device) {
703                 ide_unlock_host(hwif->host);
704                 ide_plug_device(drive);
705         }
706 }
707
708 /**
709  *      unexpected_intr         -       handle an unexpected IDE interrupt
710  *      @irq: interrupt line
711  *      @hwif: port being processed
712  *
713  *      There's nothing really useful we can do with an unexpected interrupt,
714  *      other than reading the status register (to clear it), and logging it.
715  *      There should be no way that an irq can happen before we're ready for it,
716  *      so we needn't worry much about losing an "important" interrupt here.
717  *
718  *      On laptops (and "green" PCs), an unexpected interrupt occurs whenever
719  *      the drive enters "idle", "standby", or "sleep" mode, so if the status
720  *      looks "good", we just ignore the interrupt completely.
721  *
722  *      This routine assumes __cli() is in effect when called.
723  *
724  *      If an unexpected interrupt happens on irq15 while we are handling irq14
725  *      and if the two interfaces are "serialized" (CMD640), then it looks like
726  *      we could screw up by interfering with a new request being set up for 
727  *      irq15.
728  *
729  *      In reality, this is a non-issue.  The new command is not sent unless 
730  *      the drive is ready to accept one, in which case we know the drive is
731  *      not trying to interrupt us.  And ide_set_handler() is always invoked
732  *      before completing the issuance of any new drive command, so we will not
733  *      be accidentally invoked as a result of any valid command completion
734  *      interrupt.
735  */
736
737 static void unexpected_intr(int irq, ide_hwif_t *hwif)
738 {
739         u8 stat = hwif->tp_ops->read_status(hwif);
740
741         if (!OK_STAT(stat, ATA_DRDY, BAD_STAT)) {
742                 /* Try to not flood the console with msgs */
743                 static unsigned long last_msgtime, count;
744                 ++count;
745
746                 if (time_after(jiffies, last_msgtime + HZ)) {
747                         last_msgtime = jiffies;
748                         printk(KERN_ERR "%s: unexpected interrupt, "
749                                 "status=0x%02x, count=%ld\n",
750                                 hwif->name, stat, count);
751                 }
752         }
753 }
754
755 /**
756  *      ide_intr        -       default IDE interrupt handler
757  *      @irq: interrupt number
758  *      @dev_id: hwif
759  *      @regs: unused weirdness from the kernel irq layer
760  *
761  *      This is the default IRQ handler for the IDE layer. You should
762  *      not need to override it. If you do be aware it is subtle in
763  *      places
764  *
765  *      hwif is the interface in the group currently performing
766  *      a command. hwif->cur_dev is the drive and hwif->handler is
767  *      the IRQ handler to call. As we issue a command the handlers
768  *      step through multiple states, reassigning the handler to the
769  *      next step in the process. Unlike a smart SCSI controller IDE
770  *      expects the main processor to sequence the various transfer
771  *      stages. We also manage a poll timer to catch up with most
772  *      timeout situations. There are still a few where the handlers
773  *      don't ever decide to give up.
774  *
775  *      The handler eventually returns ide_stopped to indicate the
776  *      request completed. At this point we issue the next request
777  *      on the port and the process begins again.
778  */
779
780 irqreturn_t ide_intr (int irq, void *dev_id)
781 {
782         ide_hwif_t *hwif = (ide_hwif_t *)dev_id;
783         struct ide_host *host = hwif->host;
784         ide_drive_t *uninitialized_var(drive);
785         ide_handler_t *handler;
786         unsigned long flags;
787         ide_startstop_t startstop;
788         irqreturn_t irq_ret = IRQ_NONE;
789         int plug_device = 0;
790
791         if (host->host_flags & IDE_HFLAG_SERIALIZE) {
792                 if (hwif != host->cur_port)
793                         goto out_early;
794         }
795
796         spin_lock_irqsave(&hwif->lock, flags);
797
798         if (hwif->ack_intr && hwif->ack_intr(hwif) == 0)
799                 goto out;
800
801         handler = hwif->handler;
802
803         if (handler == NULL || hwif->polling) {
804                 /*
805                  * Not expecting an interrupt from this drive.
806                  * That means this could be:
807                  *      (1) an interrupt from another PCI device
808                  *      sharing the same PCI INT# as us.
809                  * or   (2) a drive just entered sleep or standby mode,
810                  *      and is interrupting to let us know.
811                  * or   (3) a spurious interrupt of unknown origin.
812                  *
813                  * For PCI, we cannot tell the difference,
814                  * so in that case we just ignore it and hope it goes away.
815                  */
816                 if ((host->irq_flags & IRQF_SHARED) == 0) {
817                         /*
818                          * Probably not a shared PCI interrupt,
819                          * so we can safely try to do something about it:
820                          */
821                         unexpected_intr(irq, hwif);
822                 } else {
823                         /*
824                          * Whack the status register, just in case
825                          * we have a leftover pending IRQ.
826                          */
827                         (void)hwif->tp_ops->read_status(hwif);
828                 }
829                 goto out;
830         }
831
832         drive = hwif->cur_dev;
833
834         if (!drive_is_ready(drive))
835                 /*
836                  * This happens regularly when we share a PCI IRQ with
837                  * another device.  Unfortunately, it can also happen
838                  * with some buggy drives that trigger the IRQ before
839                  * their status register is up to date.  Hopefully we have
840                  * enough advance overhead that the latter isn't a problem.
841                  */
842                 goto out;
843
844         hwif->handler = NULL;
845         hwif->expiry = NULL;
846         hwif->req_gen++;
847         del_timer(&hwif->timer);
848         spin_unlock(&hwif->lock);
849
850         if (hwif->port_ops && hwif->port_ops->clear_irq)
851                 hwif->port_ops->clear_irq(drive);
852
853         if (drive->dev_flags & IDE_DFLAG_UNMASK)
854                 local_irq_enable_in_hardirq();
855
856         /* service this interrupt, may set handler for next interrupt */
857         startstop = handler(drive);
858
859         spin_lock_irq(&hwif->lock);
860         /*
861          * Note that handler() may have set things up for another
862          * interrupt to occur soon, but it cannot happen until
863          * we exit from this routine, because it will be the
864          * same irq as is currently being serviced here, and Linux
865          * won't allow another of the same (on any CPU) until we return.
866          */
867         if (startstop == ide_stopped) {
868                 BUG_ON(hwif->handler);
869                 ide_unlock_port(hwif);
870                 plug_device = 1;
871         }
872         irq_ret = IRQ_HANDLED;
873 out:
874         spin_unlock_irqrestore(&hwif->lock, flags);
875 out_early:
876         if (plug_device) {
877                 ide_unlock_host(hwif->host);
878                 ide_plug_device(drive);
879         }
880
881         return irq_ret;
882 }
883 EXPORT_SYMBOL_GPL(ide_intr);
884
885 void ide_pad_transfer(ide_drive_t *drive, int write, int len)
886 {
887         ide_hwif_t *hwif = drive->hwif;
888         u8 buf[4] = { 0 };
889
890         while (len > 0) {
891                 if (write)
892                         hwif->tp_ops->output_data(drive, NULL, buf, min(4, len));
893                 else
894                         hwif->tp_ops->input_data(drive, NULL, buf, min(4, len));
895                 len -= 4;
896         }
897 }
898 EXPORT_SYMBOL_GPL(ide_pad_transfer);