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

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