ide-io.c revision 374e042c3e767ac2e5a40b78529220e0b3de793c
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
57static int __ide_end_request(ide_drive_t *drive, struct request *rq,
58			     int uptodate, unsigned int nr_bytes, int dequeue)
59{
60	int ret = 1;
61	int error = 0;
62
63	if (uptodate <= 0)
64		error = uptodate ? uptodate : -EIO;
65
66	/*
67	 * if failfast is set on a request, override number of sectors and
68	 * complete the whole request right now
69	 */
70	if (blk_noretry_request(rq) && error)
71		nr_bytes = rq->hard_nr_sectors << 9;
72
73	if (!blk_fs_request(rq) && error && !rq->errors)
74		rq->errors = -EIO;
75
76	/*
77	 * decide whether to reenable DMA -- 3 is a random magic for now,
78	 * if we DMA timeout more than 3 times, just stay in PIO
79	 */
80	if (drive->state == DMA_PIO_RETRY && drive->retry_pio <= 3) {
81		drive->state = 0;
82		ide_dma_on(drive);
83	}
84
85	if (!__blk_end_request(rq, error, nr_bytes)) {
86		if (dequeue)
87			HWGROUP(drive)->rq = NULL;
88		ret = 0;
89	}
90
91	return ret;
92}
93
94/**
95 *	ide_end_request		-	complete an IDE I/O
96 *	@drive: IDE device for the I/O
97 *	@uptodate:
98 *	@nr_sectors: number of sectors completed
99 *
100 *	This is our end_request wrapper function. We complete the I/O
101 *	update random number input and dequeue the request, which if
102 *	it was tagged may be out of order.
103 */
104
105int ide_end_request (ide_drive_t *drive, int uptodate, int nr_sectors)
106{
107	unsigned int nr_bytes = nr_sectors << 9;
108	struct request *rq;
109	unsigned long flags;
110	int ret = 1;
111
112	/*
113	 * room for locking improvements here, the calls below don't
114	 * need the queue lock held at all
115	 */
116	spin_lock_irqsave(&ide_lock, flags);
117	rq = HWGROUP(drive)->rq;
118
119	if (!nr_bytes) {
120		if (blk_pc_request(rq))
121			nr_bytes = rq->data_len;
122		else
123			nr_bytes = rq->hard_cur_sectors << 9;
124	}
125
126	ret = __ide_end_request(drive, rq, uptodate, nr_bytes, 1);
127
128	spin_unlock_irqrestore(&ide_lock, flags);
129	return ret;
130}
131EXPORT_SYMBOL(ide_end_request);
132
133/*
134 * Power Management state machine. This one is rather trivial for now,
135 * we should probably add more, like switching back to PIO on suspend
136 * to help some BIOSes, re-do the door locking on resume, etc...
137 */
138
139enum {
140	ide_pm_flush_cache	= ide_pm_state_start_suspend,
141	idedisk_pm_standby,
142
143	idedisk_pm_restore_pio	= ide_pm_state_start_resume,
144	idedisk_pm_idle,
145	ide_pm_restore_dma,
146};
147
148static void ide_complete_power_step(ide_drive_t *drive, struct request *rq, u8 stat, u8 error)
149{
150	struct request_pm_state *pm = rq->data;
151
152	if (drive->media != ide_disk)
153		return;
154
155	switch (pm->pm_step) {
156	case ide_pm_flush_cache:	/* Suspend step 1 (flush cache) complete */
157		if (pm->pm_state == PM_EVENT_FREEZE)
158			pm->pm_step = ide_pm_state_completed;
159		else
160			pm->pm_step = idedisk_pm_standby;
161		break;
162	case idedisk_pm_standby:	/* Suspend step 2 (standby) complete */
163		pm->pm_step = ide_pm_state_completed;
164		break;
165	case idedisk_pm_restore_pio:	/* Resume step 1 complete */
166		pm->pm_step = idedisk_pm_idle;
167		break;
168	case idedisk_pm_idle:		/* Resume step 2 (idle) complete */
169		pm->pm_step = ide_pm_restore_dma;
170		break;
171	}
172}
173
174static ide_startstop_t ide_start_power_step(ide_drive_t *drive, struct request *rq)
175{
176	struct request_pm_state *pm = rq->data;
177	ide_task_t *args = rq->special;
178
179	memset(args, 0, sizeof(*args));
180
181	switch (pm->pm_step) {
182	case ide_pm_flush_cache:	/* Suspend step 1 (flush cache) */
183		if (drive->media != ide_disk)
184			break;
185		/* Not supported? Switch to next step now. */
186		if (!drive->wcache || !ide_id_has_flush_cache(drive->id)) {
187			ide_complete_power_step(drive, rq, 0, 0);
188			return ide_stopped;
189		}
190		if (ide_id_has_flush_cache_ext(drive->id))
191			args->tf.command = WIN_FLUSH_CACHE_EXT;
192		else
193			args->tf.command = WIN_FLUSH_CACHE;
194		goto out_do_tf;
195
196	case idedisk_pm_standby:	/* Suspend step 2 (standby) */
197		args->tf.command = WIN_STANDBYNOW1;
198		goto out_do_tf;
199
200	case idedisk_pm_restore_pio:	/* Resume step 1 (restore PIO) */
201		ide_set_max_pio(drive);
202		/*
203		 * skip idedisk_pm_idle for ATAPI devices
204		 */
205		if (drive->media != ide_disk)
206			pm->pm_step = ide_pm_restore_dma;
207		else
208			ide_complete_power_step(drive, rq, 0, 0);
209		return ide_stopped;
210
211	case idedisk_pm_idle:		/* Resume step 2 (idle) */
212		args->tf.command = WIN_IDLEIMMEDIATE;
213		goto out_do_tf;
214
215	case ide_pm_restore_dma:	/* Resume step 3 (restore DMA) */
216		/*
217		 * Right now, all we do is call ide_set_dma(drive),
218		 * we could be smarter and check for current xfer_speed
219		 * in struct drive etc...
220		 */
221		if (drive->hwif->dma_ops == NULL)
222			break;
223		/*
224		 * TODO: respect ->using_dma setting
225		 */
226		ide_set_dma(drive);
227		break;
228	}
229	pm->pm_step = ide_pm_state_completed;
230	return ide_stopped;
231
232out_do_tf:
233	args->tf_flags	 = IDE_TFLAG_TF | IDE_TFLAG_DEVICE;
234	args->data_phase = TASKFILE_NO_DATA;
235	return do_rw_taskfile(drive, args);
236}
237
238/**
239 *	ide_end_dequeued_request	-	complete an IDE I/O
240 *	@drive: IDE device for the I/O
241 *	@uptodate:
242 *	@nr_sectors: number of sectors completed
243 *
244 *	Complete an I/O that is no longer on the request queue. This
245 *	typically occurs when we pull the request and issue a REQUEST_SENSE.
246 *	We must still finish the old request but we must not tamper with the
247 *	queue in the meantime.
248 *
249 *	NOTE: This path does not handle barrier, but barrier is not supported
250 *	on ide-cd anyway.
251 */
252
253int ide_end_dequeued_request(ide_drive_t *drive, struct request *rq,
254			     int uptodate, int nr_sectors)
255{
256	unsigned long flags;
257	int ret;
258
259	spin_lock_irqsave(&ide_lock, flags);
260	BUG_ON(!blk_rq_started(rq));
261	ret = __ide_end_request(drive, rq, uptodate, nr_sectors << 9, 0);
262	spin_unlock_irqrestore(&ide_lock, flags);
263
264	return ret;
265}
266EXPORT_SYMBOL_GPL(ide_end_dequeued_request);
267
268
269/**
270 *	ide_complete_pm_request - end the current Power Management request
271 *	@drive: target drive
272 *	@rq: request
273 *
274 *	This function cleans up the current PM request and stops the queue
275 *	if necessary.
276 */
277static void ide_complete_pm_request (ide_drive_t *drive, struct request *rq)
278{
279	unsigned long flags;
280
281#ifdef DEBUG_PM
282	printk("%s: completing PM request, %s\n", drive->name,
283	       blk_pm_suspend_request(rq) ? "suspend" : "resume");
284#endif
285	spin_lock_irqsave(&ide_lock, flags);
286	if (blk_pm_suspend_request(rq)) {
287		blk_stop_queue(drive->queue);
288	} else {
289		drive->blocked = 0;
290		blk_start_queue(drive->queue);
291	}
292	HWGROUP(drive)->rq = NULL;
293	if (__blk_end_request(rq, 0, 0))
294		BUG();
295	spin_unlock_irqrestore(&ide_lock, flags);
296}
297
298/**
299 *	ide_end_drive_cmd	-	end an explicit drive command
300 *	@drive: command
301 *	@stat: status bits
302 *	@err: error bits
303 *
304 *	Clean up after success/failure of an explicit drive command.
305 *	These get thrown onto the queue so they are synchronized with
306 *	real I/O operations on the drive.
307 *
308 *	In LBA48 mode we have to read the register set twice to get
309 *	all the extra information out.
310 */
311
312void ide_end_drive_cmd (ide_drive_t *drive, u8 stat, u8 err)
313{
314	unsigned long flags;
315	struct request *rq;
316
317	spin_lock_irqsave(&ide_lock, flags);
318	rq = HWGROUP(drive)->rq;
319	spin_unlock_irqrestore(&ide_lock, flags);
320
321	if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE) {
322		ide_task_t *task = (ide_task_t *)rq->special;
323
324		if (rq->errors == 0)
325			rq->errors = !OK_STAT(stat, READY_STAT, BAD_STAT);
326
327		if (task) {
328			struct ide_taskfile *tf = &task->tf;
329
330			tf->error = err;
331			tf->status = stat;
332
333			drive->hwif->tp_ops->tf_read(drive, task);
334
335			if (task->tf_flags & IDE_TFLAG_DYN)
336				kfree(task);
337		}
338	} else if (blk_pm_request(rq)) {
339		struct request_pm_state *pm = rq->data;
340#ifdef DEBUG_PM
341		printk("%s: complete_power_step(step: %d, stat: %x, err: %x)\n",
342			drive->name, rq->pm->pm_step, stat, err);
343#endif
344		ide_complete_power_step(drive, rq, stat, err);
345		if (pm->pm_step == ide_pm_state_completed)
346			ide_complete_pm_request(drive, rq);
347		return;
348	}
349
350	spin_lock_irqsave(&ide_lock, flags);
351	HWGROUP(drive)->rq = NULL;
352	rq->errors = err;
353	if (unlikely(__blk_end_request(rq, (rq->errors ? -EIO : 0),
354				       blk_rq_bytes(rq))))
355		BUG();
356	spin_unlock_irqrestore(&ide_lock, flags);
357}
358
359EXPORT_SYMBOL(ide_end_drive_cmd);
360
361static void ide_kill_rq(ide_drive_t *drive, struct request *rq)
362{
363	if (rq->rq_disk) {
364		ide_driver_t *drv;
365
366		drv = *(ide_driver_t **)rq->rq_disk->private_data;
367		drv->end_request(drive, 0, 0);
368	} else
369		ide_end_request(drive, 0, 0);
370}
371
372static ide_startstop_t ide_ata_error(ide_drive_t *drive, struct request *rq, u8 stat, u8 err)
373{
374	ide_hwif_t *hwif = drive->hwif;
375
376	if (stat & BUSY_STAT || ((stat & WRERR_STAT) && !drive->nowerr)) {
377		/* other bits are useless when BUSY */
378		rq->errors |= ERROR_RESET;
379	} else if (stat & ERR_STAT) {
380		/* err has different meaning on cdrom and tape */
381		if (err == ABRT_ERR) {
382			if (drive->select.b.lba &&
383			    /* some newer drives don't support WIN_SPECIFY */
384			    hwif->tp_ops->read_status(hwif) == WIN_SPECIFY)
385				return ide_stopped;
386		} else if ((err & BAD_CRC) == BAD_CRC) {
387			/* UDMA crc error, just retry the operation */
388			drive->crc_count++;
389		} else if (err & (BBD_ERR | ECC_ERR)) {
390			/* retries won't help these */
391			rq->errors = ERROR_MAX;
392		} else if (err & TRK0_ERR) {
393			/* help it find track zero */
394			rq->errors |= ERROR_RECAL;
395		}
396	}
397
398	if ((stat & DRQ_STAT) && rq_data_dir(rq) == READ &&
399	    (hwif->host_flags & IDE_HFLAG_ERROR_STOPS_FIFO) == 0) {
400		int nsect = drive->mult_count ? drive->mult_count : 1;
401
402		ide_pad_transfer(drive, READ, nsect * SECTOR_SIZE);
403	}
404
405	if (rq->errors >= ERROR_MAX || blk_noretry_request(rq)) {
406		ide_kill_rq(drive, rq);
407		return ide_stopped;
408	}
409
410	if (hwif->tp_ops->read_status(hwif) & (BUSY_STAT | DRQ_STAT))
411		rq->errors |= ERROR_RESET;
412
413	if ((rq->errors & ERROR_RESET) == ERROR_RESET) {
414		++rq->errors;
415		return ide_do_reset(drive);
416	}
417
418	if ((rq->errors & ERROR_RECAL) == ERROR_RECAL)
419		drive->special.b.recalibrate = 1;
420
421	++rq->errors;
422
423	return ide_stopped;
424}
425
426static ide_startstop_t ide_atapi_error(ide_drive_t *drive, struct request *rq, u8 stat, u8 err)
427{
428	ide_hwif_t *hwif = drive->hwif;
429
430	if (stat & BUSY_STAT || ((stat & WRERR_STAT) && !drive->nowerr)) {
431		/* other bits are useless when BUSY */
432		rq->errors |= ERROR_RESET;
433	} else {
434		/* add decoding error stuff */
435	}
436
437	if (hwif->tp_ops->read_status(hwif) & (BUSY_STAT | DRQ_STAT))
438		/* force an abort */
439		hwif->tp_ops->exec_command(hwif, WIN_IDLEIMMEDIATE);
440
441	if (rq->errors >= ERROR_MAX) {
442		ide_kill_rq(drive, rq);
443	} else {
444		if ((rq->errors & ERROR_RESET) == ERROR_RESET) {
445			++rq->errors;
446			return ide_do_reset(drive);
447		}
448		++rq->errors;
449	}
450
451	return ide_stopped;
452}
453
454ide_startstop_t
455__ide_error(ide_drive_t *drive, struct request *rq, u8 stat, u8 err)
456{
457	if (drive->media == ide_disk)
458		return ide_ata_error(drive, rq, stat, err);
459	return ide_atapi_error(drive, rq, stat, err);
460}
461
462EXPORT_SYMBOL_GPL(__ide_error);
463
464/**
465 *	ide_error	-	handle an error on the IDE
466 *	@drive: drive the error occurred on
467 *	@msg: message to report
468 *	@stat: status bits
469 *
470 *	ide_error() takes action based on the error returned by the drive.
471 *	For normal I/O that may well include retries. We deal with
472 *	both new-style (taskfile) and old style command handling here.
473 *	In the case of taskfile command handling there is work left to
474 *	do
475 */
476
477ide_startstop_t ide_error (ide_drive_t *drive, const char *msg, u8 stat)
478{
479	struct request *rq;
480	u8 err;
481
482	err = ide_dump_status(drive, msg, stat);
483
484	if ((rq = HWGROUP(drive)->rq) == NULL)
485		return ide_stopped;
486
487	/* retry only "normal" I/O: */
488	if (!blk_fs_request(rq)) {
489		rq->errors = 1;
490		ide_end_drive_cmd(drive, stat, err);
491		return ide_stopped;
492	}
493
494	if (rq->rq_disk) {
495		ide_driver_t *drv;
496
497		drv = *(ide_driver_t **)rq->rq_disk->private_data;
498		return drv->error(drive, rq, stat, err);
499	} else
500		return __ide_error(drive, rq, stat, err);
501}
502
503EXPORT_SYMBOL_GPL(ide_error);
504
505static void ide_tf_set_specify_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
506{
507	tf->nsect   = drive->sect;
508	tf->lbal    = drive->sect;
509	tf->lbam    = drive->cyl;
510	tf->lbah    = drive->cyl >> 8;
511	tf->device  = ((drive->head - 1) | drive->select.all) & ~ATA_LBA;
512	tf->command = WIN_SPECIFY;
513}
514
515static void ide_tf_set_restore_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
516{
517	tf->nsect   = drive->sect;
518	tf->command = WIN_RESTORE;
519}
520
521static void ide_tf_set_setmult_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
522{
523	tf->nsect   = drive->mult_req;
524	tf->command = WIN_SETMULT;
525}
526
527static ide_startstop_t ide_disk_special(ide_drive_t *drive)
528{
529	special_t *s = &drive->special;
530	ide_task_t args;
531
532	memset(&args, 0, sizeof(ide_task_t));
533	args.data_phase = TASKFILE_NO_DATA;
534
535	if (s->b.set_geometry) {
536		s->b.set_geometry = 0;
537		ide_tf_set_specify_cmd(drive, &args.tf);
538	} else if (s->b.recalibrate) {
539		s->b.recalibrate = 0;
540		ide_tf_set_restore_cmd(drive, &args.tf);
541	} else if (s->b.set_multmode) {
542		s->b.set_multmode = 0;
543		if (drive->mult_req > drive->id->max_multsect)
544			drive->mult_req = drive->id->max_multsect;
545		ide_tf_set_setmult_cmd(drive, &args.tf);
546	} else if (s->all) {
547		int special = s->all;
548		s->all = 0;
549		printk(KERN_ERR "%s: bad special flag: 0x%02x\n", drive->name, special);
550		return ide_stopped;
551	}
552
553	args.tf_flags = IDE_TFLAG_TF | IDE_TFLAG_DEVICE |
554			IDE_TFLAG_CUSTOM_HANDLER;
555
556	do_rw_taskfile(drive, &args);
557
558	return ide_started;
559}
560
561/*
562 * handle HDIO_SET_PIO_MODE ioctl abusers here, eventually it will go away
563 */
564static int set_pio_mode_abuse(ide_hwif_t *hwif, u8 req_pio)
565{
566	switch (req_pio) {
567	case 202:
568	case 201:
569	case 200:
570	case 102:
571	case 101:
572	case 100:
573		return (hwif->host_flags & IDE_HFLAG_ABUSE_DMA_MODES) ? 1 : 0;
574	case 9:
575	case 8:
576		return (hwif->host_flags & IDE_HFLAG_ABUSE_PREFETCH) ? 1 : 0;
577	case 7:
578	case 6:
579		return (hwif->host_flags & IDE_HFLAG_ABUSE_FAST_DEVSEL) ? 1 : 0;
580	default:
581		return 0;
582	}
583}
584
585/**
586 *	do_special		-	issue some special commands
587 *	@drive: drive the command is for
588 *
589 *	do_special() is used to issue WIN_SPECIFY, WIN_RESTORE, and WIN_SETMULT
590 *	commands to a drive.  It used to do much more, but has been scaled
591 *	back.
592 */
593
594static ide_startstop_t do_special (ide_drive_t *drive)
595{
596	special_t *s = &drive->special;
597
598#ifdef DEBUG
599	printk("%s: do_special: 0x%02x\n", drive->name, s->all);
600#endif
601	if (s->b.set_tune) {
602		ide_hwif_t *hwif = drive->hwif;
603		const struct ide_port_ops *port_ops = hwif->port_ops;
604		u8 req_pio = drive->tune_req;
605
606		s->b.set_tune = 0;
607
608		if (set_pio_mode_abuse(drive->hwif, req_pio)) {
609			/*
610			 * take ide_lock for drive->[no_]unmask/[no_]io_32bit
611			 */
612			if (req_pio == 8 || req_pio == 9) {
613				unsigned long flags;
614
615				spin_lock_irqsave(&ide_lock, flags);
616				port_ops->set_pio_mode(drive, req_pio);
617				spin_unlock_irqrestore(&ide_lock, flags);
618			} else
619				port_ops->set_pio_mode(drive, req_pio);
620		} else {
621			int keep_dma = drive->using_dma;
622
623			ide_set_pio(drive, req_pio);
624
625			if (hwif->host_flags & IDE_HFLAG_SET_PIO_MODE_KEEP_DMA) {
626				if (keep_dma)
627					ide_dma_on(drive);
628			}
629		}
630
631		return ide_stopped;
632	} else {
633		if (drive->media == ide_disk)
634			return ide_disk_special(drive);
635
636		s->all = 0;
637		drive->mult_req = 0;
638		return ide_stopped;
639	}
640}
641
642void ide_map_sg(ide_drive_t *drive, struct request *rq)
643{
644	ide_hwif_t *hwif = drive->hwif;
645	struct scatterlist *sg = hwif->sg_table;
646
647	if (hwif->sg_mapped)	/* needed by ide-scsi */
648		return;
649
650	if (rq->cmd_type != REQ_TYPE_ATA_TASKFILE) {
651		hwif->sg_nents = blk_rq_map_sg(drive->queue, rq, sg);
652	} else {
653		sg_init_one(sg, rq->buffer, rq->nr_sectors * SECTOR_SIZE);
654		hwif->sg_nents = 1;
655	}
656}
657
658EXPORT_SYMBOL_GPL(ide_map_sg);
659
660void ide_init_sg_cmd(ide_drive_t *drive, struct request *rq)
661{
662	ide_hwif_t *hwif = drive->hwif;
663
664	hwif->nsect = hwif->nleft = rq->nr_sectors;
665	hwif->cursg_ofs = 0;
666	hwif->cursg = NULL;
667}
668
669EXPORT_SYMBOL_GPL(ide_init_sg_cmd);
670
671/**
672 *	execute_drive_command	-	issue special drive command
673 *	@drive: the drive to issue the command on
674 *	@rq: the request structure holding the command
675 *
676 *	execute_drive_cmd() issues a special drive command,  usually
677 *	initiated by ioctl() from the external hdparm program. The
678 *	command can be a drive command, drive task or taskfile
679 *	operation. Weirdly you can call it with NULL to wait for
680 *	all commands to finish. Don't do this as that is due to change
681 */
682
683static ide_startstop_t execute_drive_cmd (ide_drive_t *drive,
684		struct request *rq)
685{
686	ide_hwif_t *hwif = HWIF(drive);
687	ide_task_t *task = rq->special;
688
689	if (task) {
690		hwif->data_phase = task->data_phase;
691
692		switch (hwif->data_phase) {
693		case TASKFILE_MULTI_OUT:
694		case TASKFILE_OUT:
695		case TASKFILE_MULTI_IN:
696		case TASKFILE_IN:
697			ide_init_sg_cmd(drive, rq);
698			ide_map_sg(drive, rq);
699		default:
700			break;
701		}
702
703		return do_rw_taskfile(drive, task);
704	}
705
706 	/*
707 	 * NULL is actually a valid way of waiting for
708 	 * all current requests to be flushed from the queue.
709 	 */
710#ifdef DEBUG
711 	printk("%s: DRIVE_CMD (null)\n", drive->name);
712#endif
713	ide_end_drive_cmd(drive, hwif->tp_ops->read_status(hwif),
714			  ide_read_error(drive));
715
716 	return ide_stopped;
717}
718
719static ide_startstop_t ide_special_rq(ide_drive_t *drive, struct request *rq)
720{
721	switch (rq->cmd[0]) {
722	case REQ_DRIVE_RESET:
723		return ide_do_reset(drive);
724	default:
725		blk_dump_rq_flags(rq, "ide_special_rq - bad request");
726		ide_end_request(drive, 0, 0);
727		return ide_stopped;
728	}
729}
730
731static void ide_check_pm_state(ide_drive_t *drive, struct request *rq)
732{
733	struct request_pm_state *pm = rq->data;
734
735	if (blk_pm_suspend_request(rq) &&
736	    pm->pm_step == ide_pm_state_start_suspend)
737		/* Mark drive blocked when starting the suspend sequence. */
738		drive->blocked = 1;
739	else if (blk_pm_resume_request(rq) &&
740		 pm->pm_step == ide_pm_state_start_resume) {
741		/*
742		 * The first thing we do on wakeup is to wait for BSY bit to
743		 * go away (with a looong timeout) as a drive on this hwif may
744		 * just be POSTing itself.
745		 * We do that before even selecting as the "other" device on
746		 * the bus may be broken enough to walk on our toes at this
747		 * point.
748		 */
749		ide_hwif_t *hwif = drive->hwif;
750		int rc;
751#ifdef DEBUG_PM
752		printk("%s: Wakeup request inited, waiting for !BSY...\n", drive->name);
753#endif
754		rc = ide_wait_not_busy(hwif, 35000);
755		if (rc)
756			printk(KERN_WARNING "%s: bus not ready on wakeup\n", drive->name);
757		SELECT_DRIVE(drive);
758		hwif->tp_ops->set_irq(hwif, 1);
759		rc = ide_wait_not_busy(hwif, 100000);
760		if (rc)
761			printk(KERN_WARNING "%s: drive not ready on wakeup\n", drive->name);
762	}
763}
764
765/**
766 *	start_request	-	start of I/O and command issuing for IDE
767 *
768 *	start_request() initiates handling of a new I/O request. It
769 *	accepts commands and I/O (read/write) requests. It also does
770 *	the final remapping for weird stuff like EZDrive. Once
771 *	device mapper can work sector level the EZDrive stuff can go away
772 *
773 *	FIXME: this function needs a rename
774 */
775
776static ide_startstop_t start_request (ide_drive_t *drive, struct request *rq)
777{
778	ide_startstop_t startstop;
779	sector_t block;
780
781	BUG_ON(!blk_rq_started(rq));
782
783#ifdef DEBUG
784	printk("%s: start_request: current=0x%08lx\n",
785		HWIF(drive)->name, (unsigned long) rq);
786#endif
787
788	/* bail early if we've exceeded max_failures */
789	if (drive->max_failures && (drive->failures > drive->max_failures)) {
790		rq->cmd_flags |= REQ_FAILED;
791		goto kill_rq;
792	}
793
794	block    = rq->sector;
795	if (blk_fs_request(rq) &&
796	    (drive->media == ide_disk || drive->media == ide_floppy)) {
797		block += drive->sect0;
798	}
799	/* Yecch - this will shift the entire interval,
800	   possibly killing some innocent following sector */
801	if (block == 0 && drive->remap_0_to_1 == 1)
802		block = 1;  /* redirect MBR access to EZ-Drive partn table */
803
804	if (blk_pm_request(rq))
805		ide_check_pm_state(drive, rq);
806
807	SELECT_DRIVE(drive);
808	if (ide_wait_stat(&startstop, drive, drive->ready_stat, BUSY_STAT|DRQ_STAT, WAIT_READY)) {
809		printk(KERN_ERR "%s: drive not ready for command\n", drive->name);
810		return startstop;
811	}
812	if (!drive->special.all) {
813		ide_driver_t *drv;
814
815		/*
816		 * We reset the drive so we need to issue a SETFEATURES.
817		 * Do it _after_ do_special() restored device parameters.
818		 */
819		if (drive->current_speed == 0xff)
820			ide_config_drive_speed(drive, drive->desired_speed);
821
822		if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE)
823			return execute_drive_cmd(drive, rq);
824		else if (blk_pm_request(rq)) {
825			struct request_pm_state *pm = rq->data;
826#ifdef DEBUG_PM
827			printk("%s: start_power_step(step: %d)\n",
828				drive->name, rq->pm->pm_step);
829#endif
830			startstop = ide_start_power_step(drive, rq);
831			if (startstop == ide_stopped &&
832			    pm->pm_step == ide_pm_state_completed)
833				ide_complete_pm_request(drive, rq);
834			return startstop;
835		} else if (!rq->rq_disk && blk_special_request(rq))
836			/*
837			 * TODO: Once all ULDs have been modified to
838			 * check for specific op codes rather than
839			 * blindly accepting any special request, the
840			 * check for ->rq_disk above may be replaced
841			 * by a more suitable mechanism or even
842			 * dropped entirely.
843			 */
844			return ide_special_rq(drive, rq);
845
846		drv = *(ide_driver_t **)rq->rq_disk->private_data;
847		return drv->do_request(drive, rq, block);
848	}
849	return do_special(drive);
850kill_rq:
851	ide_kill_rq(drive, rq);
852	return ide_stopped;
853}
854
855/**
856 *	ide_stall_queue		-	pause an IDE device
857 *	@drive: drive to stall
858 *	@timeout: time to stall for (jiffies)
859 *
860 *	ide_stall_queue() can be used by a drive to give excess bandwidth back
861 *	to the hwgroup by sleeping for timeout jiffies.
862 */
863
864void ide_stall_queue (ide_drive_t *drive, unsigned long timeout)
865{
866	if (timeout > WAIT_WORSTCASE)
867		timeout = WAIT_WORSTCASE;
868	drive->sleep = timeout + jiffies;
869	drive->sleeping = 1;
870}
871
872EXPORT_SYMBOL(ide_stall_queue);
873
874#define WAKEUP(drive)	((drive)->service_start + 2 * (drive)->service_time)
875
876/**
877 *	choose_drive		-	select a drive to service
878 *	@hwgroup: hardware group to select on
879 *
880 *	choose_drive() selects the next drive which will be serviced.
881 *	This is necessary because the IDE layer can't issue commands
882 *	to both drives on the same cable, unlike SCSI.
883 */
884
885static inline ide_drive_t *choose_drive (ide_hwgroup_t *hwgroup)
886{
887	ide_drive_t *drive, *best;
888
889repeat:
890	best = NULL;
891	drive = hwgroup->drive;
892
893	/*
894	 * drive is doing pre-flush, ordered write, post-flush sequence. even
895	 * though that is 3 requests, it must be seen as a single transaction.
896	 * we must not preempt this drive until that is complete
897	 */
898	if (blk_queue_flushing(drive->queue)) {
899		/*
900		 * small race where queue could get replugged during
901		 * the 3-request flush cycle, just yank the plug since
902		 * we want it to finish asap
903		 */
904		blk_remove_plug(drive->queue);
905		return drive;
906	}
907
908	do {
909		if ((!drive->sleeping || time_after_eq(jiffies, drive->sleep))
910		    && !elv_queue_empty(drive->queue)) {
911			if (!best
912			 || (drive->sleeping && (!best->sleeping || time_before(drive->sleep, best->sleep)))
913			 || (!best->sleeping && time_before(WAKEUP(drive), WAKEUP(best))))
914			{
915				if (!blk_queue_plugged(drive->queue))
916					best = drive;
917			}
918		}
919	} while ((drive = drive->next) != hwgroup->drive);
920	if (best && best->nice1 && !best->sleeping && best != hwgroup->drive && best->service_time > WAIT_MIN_SLEEP) {
921		long t = (signed long)(WAKEUP(best) - jiffies);
922		if (t >= WAIT_MIN_SLEEP) {
923		/*
924		 * We *may* have some time to spare, but first let's see if
925		 * someone can potentially benefit from our nice mood today..
926		 */
927			drive = best->next;
928			do {
929				if (!drive->sleeping
930				 && time_before(jiffies - best->service_time, WAKEUP(drive))
931				 && time_before(WAKEUP(drive), jiffies + t))
932				{
933					ide_stall_queue(best, min_t(long, t, 10 * WAIT_MIN_SLEEP));
934					goto repeat;
935				}
936			} while ((drive = drive->next) != best);
937		}
938	}
939	return best;
940}
941
942/*
943 * Issue a new request to a drive from hwgroup
944 * Caller must have already done spin_lock_irqsave(&ide_lock, ..);
945 *
946 * A hwgroup is a serialized group of IDE interfaces.  Usually there is
947 * exactly one hwif (interface) per hwgroup, but buggy controllers (eg. CMD640)
948 * may have both interfaces in a single hwgroup to "serialize" access.
949 * Or possibly multiple ISA interfaces can share a common IRQ by being grouped
950 * together into one hwgroup for serialized access.
951 *
952 * Note also that several hwgroups can end up sharing a single IRQ,
953 * possibly along with many other devices.  This is especially common in
954 * PCI-based systems with off-board IDE controller cards.
955 *
956 * The IDE driver uses the single global ide_lock spinlock to protect
957 * access to the request queues, and to protect the hwgroup->busy flag.
958 *
959 * The first thread into the driver for a particular hwgroup sets the
960 * hwgroup->busy flag to indicate that this hwgroup is now active,
961 * and then initiates processing of the top request from the request queue.
962 *
963 * Other threads attempting entry notice the busy setting, and will simply
964 * queue their new requests and exit immediately.  Note that hwgroup->busy
965 * remains set even when the driver is merely awaiting the next interrupt.
966 * Thus, the meaning is "this hwgroup is busy processing a request".
967 *
968 * When processing of a request completes, the completing thread or IRQ-handler
969 * will start the next request from the queue.  If no more work remains,
970 * the driver will clear the hwgroup->busy flag and exit.
971 *
972 * The ide_lock (spinlock) is used to protect all access to the
973 * hwgroup->busy flag, but is otherwise not needed for most processing in
974 * the driver.  This makes the driver much more friendlier to shared IRQs
975 * than previous designs, while remaining 100% (?) SMP safe and capable.
976 */
977static void ide_do_request (ide_hwgroup_t *hwgroup, int masked_irq)
978{
979	ide_drive_t	*drive;
980	ide_hwif_t	*hwif;
981	struct request	*rq;
982	ide_startstop_t	startstop;
983	int             loops = 0;
984
985	/* for atari only: POSSIBLY BROKEN HERE(?) */
986	ide_get_lock(ide_intr, hwgroup);
987
988	/* caller must own ide_lock */
989	BUG_ON(!irqs_disabled());
990
991	while (!hwgroup->busy) {
992		hwgroup->busy = 1;
993		drive = choose_drive(hwgroup);
994		if (drive == NULL) {
995			int sleeping = 0;
996			unsigned long sleep = 0; /* shut up, gcc */
997			hwgroup->rq = NULL;
998			drive = hwgroup->drive;
999			do {
1000				if (drive->sleeping && (!sleeping || time_before(drive->sleep, sleep))) {
1001					sleeping = 1;
1002					sleep = drive->sleep;
1003				}
1004			} while ((drive = drive->next) != hwgroup->drive);
1005			if (sleeping) {
1006		/*
1007		 * Take a short snooze, and then wake up this hwgroup again.
1008		 * This gives other hwgroups on the same a chance to
1009		 * play fairly with us, just in case there are big differences
1010		 * in relative throughputs.. don't want to hog the cpu too much.
1011		 */
1012				if (time_before(sleep, jiffies + WAIT_MIN_SLEEP))
1013					sleep = jiffies + WAIT_MIN_SLEEP;
1014#if 1
1015				if (timer_pending(&hwgroup->timer))
1016					printk(KERN_CRIT "ide_set_handler: timer already active\n");
1017#endif
1018				/* so that ide_timer_expiry knows what to do */
1019				hwgroup->sleeping = 1;
1020				hwgroup->req_gen_timer = hwgroup->req_gen;
1021				mod_timer(&hwgroup->timer, sleep);
1022				/* we purposely leave hwgroup->busy==1
1023				 * while sleeping */
1024			} else {
1025				/* Ugly, but how can we sleep for the lock
1026				 * otherwise? perhaps from tq_disk?
1027				 */
1028
1029				/* for atari only */
1030				ide_release_lock();
1031				hwgroup->busy = 0;
1032			}
1033
1034			/* no more work for this hwgroup (for now) */
1035			return;
1036		}
1037	again:
1038		hwif = HWIF(drive);
1039		if (hwgroup->hwif->sharing_irq && hwif != hwgroup->hwif) {
1040			/*
1041			 * set nIEN for previous hwif, drives in the
1042			 * quirk_list may not like intr setups/cleanups
1043			 */
1044			if (drive->quirk_list != 1)
1045				hwif->tp_ops->set_irq(hwif, 0);
1046		}
1047		hwgroup->hwif = hwif;
1048		hwgroup->drive = drive;
1049		drive->sleeping = 0;
1050		drive->service_start = jiffies;
1051
1052		if (blk_queue_plugged(drive->queue)) {
1053			printk(KERN_ERR "ide: huh? queue was plugged!\n");
1054			break;
1055		}
1056
1057		/*
1058		 * we know that the queue isn't empty, but this can happen
1059		 * if the q->prep_rq_fn() decides to kill a request
1060		 */
1061		rq = elv_next_request(drive->queue);
1062		if (!rq) {
1063			hwgroup->busy = 0;
1064			break;
1065		}
1066
1067		/*
1068		 * Sanity: don't accept a request that isn't a PM request
1069		 * if we are currently power managed. This is very important as
1070		 * blk_stop_queue() doesn't prevent the elv_next_request()
1071		 * above to return us whatever is in the queue. Since we call
1072		 * ide_do_request() ourselves, we end up taking requests while
1073		 * the queue is blocked...
1074		 *
1075		 * We let requests forced at head of queue with ide-preempt
1076		 * though. I hope that doesn't happen too much, hopefully not
1077		 * unless the subdriver triggers such a thing in its own PM
1078		 * state machine.
1079		 *
1080		 * We count how many times we loop here to make sure we service
1081		 * all drives in the hwgroup without looping for ever
1082		 */
1083		if (drive->blocked && !blk_pm_request(rq) && !(rq->cmd_flags & REQ_PREEMPT)) {
1084			drive = drive->next ? drive->next : hwgroup->drive;
1085			if (loops++ < 4 && !blk_queue_plugged(drive->queue))
1086				goto again;
1087			/* We clear busy, there should be no pending ATA command at this point. */
1088			hwgroup->busy = 0;
1089			break;
1090		}
1091
1092		hwgroup->rq = rq;
1093
1094		/*
1095		 * Some systems have trouble with IDE IRQs arriving while
1096		 * the driver is still setting things up.  So, here we disable
1097		 * the IRQ used by this interface while the request is being started.
1098		 * This may look bad at first, but pretty much the same thing
1099		 * happens anyway when any interrupt comes in, IDE or otherwise
1100		 *  -- the kernel masks the IRQ while it is being handled.
1101		 */
1102		if (masked_irq != IDE_NO_IRQ && hwif->irq != masked_irq)
1103			disable_irq_nosync(hwif->irq);
1104		spin_unlock(&ide_lock);
1105		local_irq_enable_in_hardirq();
1106			/* allow other IRQs while we start this request */
1107		startstop = start_request(drive, rq);
1108		spin_lock_irq(&ide_lock);
1109		if (masked_irq != IDE_NO_IRQ && hwif->irq != masked_irq)
1110			enable_irq(hwif->irq);
1111		if (startstop == ide_stopped)
1112			hwgroup->busy = 0;
1113	}
1114}
1115
1116/*
1117 * Passes the stuff to ide_do_request
1118 */
1119void do_ide_request(struct request_queue *q)
1120{
1121	ide_drive_t *drive = q->queuedata;
1122
1123	ide_do_request(HWGROUP(drive), IDE_NO_IRQ);
1124}
1125
1126/*
1127 * un-busy the hwgroup etc, and clear any pending DMA status. we want to
1128 * retry the current request in pio mode instead of risking tossing it
1129 * all away
1130 */
1131static ide_startstop_t ide_dma_timeout_retry(ide_drive_t *drive, int error)
1132{
1133	ide_hwif_t *hwif = HWIF(drive);
1134	struct request *rq;
1135	ide_startstop_t ret = ide_stopped;
1136
1137	/*
1138	 * end current dma transaction
1139	 */
1140
1141	if (error < 0) {
1142		printk(KERN_WARNING "%s: DMA timeout error\n", drive->name);
1143		(void)hwif->dma_ops->dma_end(drive);
1144		ret = ide_error(drive, "dma timeout error",
1145				hwif->tp_ops->read_status(hwif));
1146	} else {
1147		printk(KERN_WARNING "%s: DMA timeout retry\n", drive->name);
1148		hwif->dma_ops->dma_timeout(drive);
1149	}
1150
1151	/*
1152	 * disable dma for now, but remember that we did so because of
1153	 * a timeout -- we'll reenable after we finish this next request
1154	 * (or rather the first chunk of it) in pio.
1155	 */
1156	drive->retry_pio++;
1157	drive->state = DMA_PIO_RETRY;
1158	ide_dma_off_quietly(drive);
1159
1160	/*
1161	 * un-busy drive etc (hwgroup->busy is cleared on return) and
1162	 * make sure request is sane
1163	 */
1164	rq = HWGROUP(drive)->rq;
1165
1166	if (!rq)
1167		goto out;
1168
1169	HWGROUP(drive)->rq = NULL;
1170
1171	rq->errors = 0;
1172
1173	if (!rq->bio)
1174		goto out;
1175
1176	rq->sector = rq->bio->bi_sector;
1177	rq->current_nr_sectors = bio_iovec(rq->bio)->bv_len >> 9;
1178	rq->hard_cur_sectors = rq->current_nr_sectors;
1179	rq->buffer = bio_data(rq->bio);
1180out:
1181	return ret;
1182}
1183
1184/**
1185 *	ide_timer_expiry	-	handle lack of an IDE interrupt
1186 *	@data: timer callback magic (hwgroup)
1187 *
1188 *	An IDE command has timed out before the expected drive return
1189 *	occurred. At this point we attempt to clean up the current
1190 *	mess. If the current handler includes an expiry handler then
1191 *	we invoke the expiry handler, and providing it is happy the
1192 *	work is done. If that fails we apply generic recovery rules
1193 *	invoking the handler and checking the drive DMA status. We
1194 *	have an excessively incestuous relationship with the DMA
1195 *	logic that wants cleaning up.
1196 */
1197
1198void ide_timer_expiry (unsigned long data)
1199{
1200	ide_hwgroup_t	*hwgroup = (ide_hwgroup_t *) data;
1201	ide_handler_t	*handler;
1202	ide_expiry_t	*expiry;
1203	unsigned long	flags;
1204	unsigned long	wait = -1;
1205
1206	spin_lock_irqsave(&ide_lock, flags);
1207
1208	if (((handler = hwgroup->handler) == NULL) ||
1209	    (hwgroup->req_gen != hwgroup->req_gen_timer)) {
1210		/*
1211		 * Either a marginal timeout occurred
1212		 * (got the interrupt just as timer expired),
1213		 * or we were "sleeping" to give other devices a chance.
1214		 * Either way, we don't really want to complain about anything.
1215		 */
1216		if (hwgroup->sleeping) {
1217			hwgroup->sleeping = 0;
1218			hwgroup->busy = 0;
1219		}
1220	} else {
1221		ide_drive_t *drive = hwgroup->drive;
1222		if (!drive) {
1223			printk(KERN_ERR "ide_timer_expiry: hwgroup->drive was NULL\n");
1224			hwgroup->handler = NULL;
1225		} else {
1226			ide_hwif_t *hwif;
1227			ide_startstop_t startstop = ide_stopped;
1228			if (!hwgroup->busy) {
1229				hwgroup->busy = 1;	/* paranoia */
1230				printk(KERN_ERR "%s: ide_timer_expiry: hwgroup->busy was 0 ??\n", drive->name);
1231			}
1232			if ((expiry = hwgroup->expiry) != NULL) {
1233				/* continue */
1234				if ((wait = expiry(drive)) > 0) {
1235					/* reset timer */
1236					hwgroup->timer.expires  = jiffies + wait;
1237					hwgroup->req_gen_timer = hwgroup->req_gen;
1238					add_timer(&hwgroup->timer);
1239					spin_unlock_irqrestore(&ide_lock, flags);
1240					return;
1241				}
1242			}
1243			hwgroup->handler = NULL;
1244			/*
1245			 * We need to simulate a real interrupt when invoking
1246			 * the handler() function, which means we need to
1247			 * globally mask the specific IRQ:
1248			 */
1249			spin_unlock(&ide_lock);
1250			hwif  = HWIF(drive);
1251			/* disable_irq_nosync ?? */
1252			disable_irq(hwif->irq);
1253			/* local CPU only,
1254			 * as if we were handling an interrupt */
1255			local_irq_disable();
1256			if (hwgroup->polling) {
1257				startstop = handler(drive);
1258			} else if (drive_is_ready(drive)) {
1259				if (drive->waiting_for_dma)
1260					hwif->dma_ops->dma_lost_irq(drive);
1261				(void)ide_ack_intr(hwif);
1262				printk(KERN_WARNING "%s: lost interrupt\n", drive->name);
1263				startstop = handler(drive);
1264			} else {
1265				if (drive->waiting_for_dma) {
1266					startstop = ide_dma_timeout_retry(drive, wait);
1267				} else
1268					startstop =
1269					ide_error(drive, "irq timeout",
1270						  hwif->tp_ops->read_status(hwif));
1271			}
1272			drive->service_time = jiffies - drive->service_start;
1273			spin_lock_irq(&ide_lock);
1274			enable_irq(hwif->irq);
1275			if (startstop == ide_stopped)
1276				hwgroup->busy = 0;
1277		}
1278	}
1279	ide_do_request(hwgroup, IDE_NO_IRQ);
1280	spin_unlock_irqrestore(&ide_lock, flags);
1281}
1282
1283/**
1284 *	unexpected_intr		-	handle an unexpected IDE interrupt
1285 *	@irq: interrupt line
1286 *	@hwgroup: hwgroup being processed
1287 *
1288 *	There's nothing really useful we can do with an unexpected interrupt,
1289 *	other than reading the status register (to clear it), and logging it.
1290 *	There should be no way that an irq can happen before we're ready for it,
1291 *	so we needn't worry much about losing an "important" interrupt here.
1292 *
1293 *	On laptops (and "green" PCs), an unexpected interrupt occurs whenever
1294 *	the drive enters "idle", "standby", or "sleep" mode, so if the status
1295 *	looks "good", we just ignore the interrupt completely.
1296 *
1297 *	This routine assumes __cli() is in effect when called.
1298 *
1299 *	If an unexpected interrupt happens on irq15 while we are handling irq14
1300 *	and if the two interfaces are "serialized" (CMD640), then it looks like
1301 *	we could screw up by interfering with a new request being set up for
1302 *	irq15.
1303 *
1304 *	In reality, this is a non-issue.  The new command is not sent unless
1305 *	the drive is ready to accept one, in which case we know the drive is
1306 *	not trying to interrupt us.  And ide_set_handler() is always invoked
1307 *	before completing the issuance of any new drive command, so we will not
1308 *	be accidentally invoked as a result of any valid command completion
1309 *	interrupt.
1310 *
1311 *	Note that we must walk the entire hwgroup here. We know which hwif
1312 *	is doing the current command, but we don't know which hwif burped
1313 *	mysteriously.
1314 */
1315
1316static void unexpected_intr (int irq, ide_hwgroup_t *hwgroup)
1317{
1318	u8 stat;
1319	ide_hwif_t *hwif = hwgroup->hwif;
1320
1321	/*
1322	 * handle the unexpected interrupt
1323	 */
1324	do {
1325		if (hwif->irq == irq) {
1326			stat = hwif->tp_ops->read_status(hwif);
1327
1328			if (!OK_STAT(stat, READY_STAT, BAD_STAT)) {
1329				/* Try to not flood the console with msgs */
1330				static unsigned long last_msgtime, count;
1331				++count;
1332				if (time_after(jiffies, last_msgtime + HZ)) {
1333					last_msgtime = jiffies;
1334					printk(KERN_ERR "%s%s: unexpected interrupt, "
1335						"status=0x%02x, count=%ld\n",
1336						hwif->name,
1337						(hwif->next==hwgroup->hwif) ? "" : "(?)", stat, count);
1338				}
1339			}
1340		}
1341	} while ((hwif = hwif->next) != hwgroup->hwif);
1342}
1343
1344/**
1345 *	ide_intr	-	default IDE interrupt handler
1346 *	@irq: interrupt number
1347 *	@dev_id: hwif group
1348 *	@regs: unused weirdness from the kernel irq layer
1349 *
1350 *	This is the default IRQ handler for the IDE layer. You should
1351 *	not need to override it. If you do be aware it is subtle in
1352 *	places
1353 *
1354 *	hwgroup->hwif is the interface in the group currently performing
1355 *	a command. hwgroup->drive is the drive and hwgroup->handler is
1356 *	the IRQ handler to call. As we issue a command the handlers
1357 *	step through multiple states, reassigning the handler to the
1358 *	next step in the process. Unlike a smart SCSI controller IDE
1359 *	expects the main processor to sequence the various transfer
1360 *	stages. We also manage a poll timer to catch up with most
1361 *	timeout situations. There are still a few where the handlers
1362 *	don't ever decide to give up.
1363 *
1364 *	The handler eventually returns ide_stopped to indicate the
1365 *	request completed. At this point we issue the next request
1366 *	on the hwgroup and the process begins again.
1367 */
1368
1369irqreturn_t ide_intr (int irq, void *dev_id)
1370{
1371	unsigned long flags;
1372	ide_hwgroup_t *hwgroup = (ide_hwgroup_t *)dev_id;
1373	ide_hwif_t *hwif;
1374	ide_drive_t *drive;
1375	ide_handler_t *handler;
1376	ide_startstop_t startstop;
1377
1378	spin_lock_irqsave(&ide_lock, flags);
1379	hwif = hwgroup->hwif;
1380
1381	if (!ide_ack_intr(hwif)) {
1382		spin_unlock_irqrestore(&ide_lock, flags);
1383		return IRQ_NONE;
1384	}
1385
1386	if ((handler = hwgroup->handler) == NULL || hwgroup->polling) {
1387		/*
1388		 * Not expecting an interrupt from this drive.
1389		 * That means this could be:
1390		 *	(1) an interrupt from another PCI device
1391		 *	sharing the same PCI INT# as us.
1392		 * or	(2) a drive just entered sleep or standby mode,
1393		 *	and is interrupting to let us know.
1394		 * or	(3) a spurious interrupt of unknown origin.
1395		 *
1396		 * For PCI, we cannot tell the difference,
1397		 * so in that case we just ignore it and hope it goes away.
1398		 *
1399		 * FIXME: unexpected_intr should be hwif-> then we can
1400		 * remove all the ifdef PCI crap
1401		 */
1402#ifdef CONFIG_BLK_DEV_IDEPCI
1403		if (hwif->chipset != ide_pci)
1404#endif	/* CONFIG_BLK_DEV_IDEPCI */
1405		{
1406			/*
1407			 * Probably not a shared PCI interrupt,
1408			 * so we can safely try to do something about it:
1409			 */
1410			unexpected_intr(irq, hwgroup);
1411#ifdef CONFIG_BLK_DEV_IDEPCI
1412		} else {
1413			/*
1414			 * Whack the status register, just in case
1415			 * we have a leftover pending IRQ.
1416			 */
1417			(void)hwif->tp_ops->read_status(hwif);
1418#endif /* CONFIG_BLK_DEV_IDEPCI */
1419		}
1420		spin_unlock_irqrestore(&ide_lock, flags);
1421		return IRQ_NONE;
1422	}
1423	drive = hwgroup->drive;
1424	if (!drive) {
1425		/*
1426		 * This should NEVER happen, and there isn't much
1427		 * we could do about it here.
1428		 *
1429		 * [Note - this can occur if the drive is hot unplugged]
1430		 */
1431		spin_unlock_irqrestore(&ide_lock, flags);
1432		return IRQ_HANDLED;
1433	}
1434	if (!drive_is_ready(drive)) {
1435		/*
1436		 * This happens regularly when we share a PCI IRQ with
1437		 * another device.  Unfortunately, it can also happen
1438		 * with some buggy drives that trigger the IRQ before
1439		 * their status register is up to date.  Hopefully we have
1440		 * enough advance overhead that the latter isn't a problem.
1441		 */
1442		spin_unlock_irqrestore(&ide_lock, flags);
1443		return IRQ_NONE;
1444	}
1445	if (!hwgroup->busy) {
1446		hwgroup->busy = 1;	/* paranoia */
1447		printk(KERN_ERR "%s: ide_intr: hwgroup->busy was 0 ??\n", drive->name);
1448	}
1449	hwgroup->handler = NULL;
1450	hwgroup->req_gen++;
1451	del_timer(&hwgroup->timer);
1452	spin_unlock(&ide_lock);
1453
1454	/* Some controllers might set DMA INTR no matter DMA or PIO;
1455	 * bmdma status might need to be cleared even for
1456	 * PIO interrupts to prevent spurious/lost irq.
1457	 */
1458	if (hwif->ide_dma_clear_irq && !(drive->waiting_for_dma))
1459		/* ide_dma_end() needs bmdma status for error checking.
1460		 * So, skip clearing bmdma status here and leave it
1461		 * to ide_dma_end() if this is dma interrupt.
1462		 */
1463		hwif->ide_dma_clear_irq(drive);
1464
1465	if (drive->unmask)
1466		local_irq_enable_in_hardirq();
1467	/* service this interrupt, may set handler for next interrupt */
1468	startstop = handler(drive);
1469	spin_lock_irq(&ide_lock);
1470
1471	/*
1472	 * Note that handler() may have set things up for another
1473	 * interrupt to occur soon, but it cannot happen until
1474	 * we exit from this routine, because it will be the
1475	 * same irq as is currently being serviced here, and Linux
1476	 * won't allow another of the same (on any CPU) until we return.
1477	 */
1478	drive->service_time = jiffies - drive->service_start;
1479	if (startstop == ide_stopped) {
1480		if (hwgroup->handler == NULL) {	/* paranoia */
1481			hwgroup->busy = 0;
1482			ide_do_request(hwgroup, hwif->irq);
1483		} else {
1484			printk(KERN_ERR "%s: ide_intr: huh? expected NULL handler "
1485				"on exit\n", drive->name);
1486		}
1487	}
1488	spin_unlock_irqrestore(&ide_lock, flags);
1489	return IRQ_HANDLED;
1490}
1491
1492/**
1493 *	ide_do_drive_cmd	-	issue IDE special command
1494 *	@drive: device to issue command
1495 *	@rq: request to issue
1496 *
1497 *	This function issues a special IDE device request
1498 *	onto the request queue.
1499 *
1500 *	the rq is queued at the head of the request queue, displacing
1501 *	the currently-being-processed request and this function
1502 *	returns immediately without waiting for the new rq to be
1503 *	completed.  This is VERY DANGEROUS, and is intended for
1504 *	careful use by the ATAPI tape/cdrom driver code.
1505 */
1506
1507void ide_do_drive_cmd(ide_drive_t *drive, struct request *rq)
1508{
1509	unsigned long flags;
1510	ide_hwgroup_t *hwgroup = HWGROUP(drive);
1511
1512	spin_lock_irqsave(&ide_lock, flags);
1513	hwgroup->rq = NULL;
1514	__elv_add_request(drive->queue, rq, ELEVATOR_INSERT_FRONT, 1);
1515	__generic_unplug_device(drive->queue);
1516	spin_unlock_irqrestore(&ide_lock, flags);
1517}
1518
1519EXPORT_SYMBOL(ide_do_drive_cmd);
1520
1521void ide_pktcmd_tf_load(ide_drive_t *drive, u32 tf_flags, u16 bcount, u8 dma)
1522{
1523	ide_hwif_t *hwif = drive->hwif;
1524	ide_task_t task;
1525
1526	memset(&task, 0, sizeof(task));
1527	task.tf_flags = IDE_TFLAG_OUT_LBAH | IDE_TFLAG_OUT_LBAM |
1528			IDE_TFLAG_OUT_FEATURE | tf_flags;
1529	task.tf.feature = dma;		/* Use PIO/DMA */
1530	task.tf.lbam    = bcount & 0xff;
1531	task.tf.lbah    = (bcount >> 8) & 0xff;
1532
1533	ide_tf_dump(drive->name, &task.tf);
1534	hwif->tp_ops->set_irq(hwif, 1);
1535	SELECT_MASK(drive, 0);
1536	hwif->tp_ops->tf_load(drive, &task);
1537}
1538
1539EXPORT_SYMBOL_GPL(ide_pktcmd_tf_load);
1540
1541void ide_pad_transfer(ide_drive_t *drive, int write, int len)
1542{
1543	ide_hwif_t *hwif = drive->hwif;
1544	u8 buf[4] = { 0 };
1545
1546	while (len > 0) {
1547		if (write)
1548			hwif->tp_ops->output_data(drive, NULL, buf, min(4, len));
1549		else
1550			hwif->tp_ops->input_data(drive, NULL, buf, min(4, len));
1551		len -= 4;
1552	}
1553}
1554EXPORT_SYMBOL_GPL(ide_pad_transfer);
1555