ide.c

GNU Mach 微内核源代码, 基于美国卡内基美隆大学的 Mach 研究项目

	((ide_hwgroup_t *)hwif->hwgroup)->drive = drive;
#if (DISK_RECOVERY_TIME > 0)
	while ((read_timer() - hwif->last_time) < DISK_RECOVERY_TIME);
#endif

#ifdef CONFIG_BLK_DEV_IDETAPE
	POLL_HWIF_TAPE_DRIVE;	/* macro from ide-tape.h */
#endif /* CONFIG_BLK_DEV_IDETAPE */

	SELECT_DRIVE(hwif,drive);
	if (ide_wait_stat(drive, drive->ready_stat, BUSY_STAT|DRQ_STAT, WAIT_READY)) {
		printk("%s: drive not ready for command\n", drive->name);
		return;
	}

	if (!drive->special.all) {
		if (rq->cmd == IDE_DRIVE_CMD) {
			execute_drive_cmd(drive, rq);
			return;
		}
#ifdef CONFIG_BLK_DEV_IDEATAPI
		switch (drive->media) {
			case ide_disk:
				do_rw_disk (drive, rq, block);
				return;
#ifdef CONFIG_BLK_DEV_IDECD
			case ide_cdrom:
				ide_do_rw_cdrom (drive, block);
				return;
#endif /* CONFIG_BLK_DEV_IDECD */
#ifdef CONFIG_BLK_DEV_IDETAPE
			case ide_tape:
				idetape_do_request (drive, rq, block);
				return;
#endif /* CONFIG_BLK_DEV_IDETAPE */
#ifdef CONFIG_BLK_DEV_IDEFLOPPY
			case ide_floppy:
				idefloppy_do_request (drive, rq, block);
				return;
#endif /* CONFIG_BLK_DEV_IDEFLOPPY */
#ifdef CONFIG_BLK_DEV_IDESCSI
			case ide_scsi:
				idescsi_do_request (drive, rq, block);
				return;
#endif /* CONFIG_BLK_DEV_IDESCSI */

			default:
				printk("%s: media type %d not supported\n",
					drive->name, drive->media);
				goto kill_rq;
		}
#else
		do_rw_disk (drive, rq, block); /* simpler and faster */
		return;
#endif /* CONFIG_BLK_DEV_IDEATAPI */
	}
	do_special(drive);
	return;
kill_rq:
	ide_end_request(0, hwif->hwgroup);
}

/*
 * The driver enables interrupts as much as possible.  In order to do this,
 * (a) the device-interrupt is always masked before entry, and
 * (b) the timeout-interrupt is always disabled before entry.
 *
 * If we enter here from, say irq14, and then start a new request for irq15,
 * (possible with "serialize" option) then we cannot ensure that we exit
 * before the irq15 hits us. So, we must be careful not to let this bother us.
 *
 * Interrupts are still masked (by default) whenever we are exchanging
 * data/cmds with a drive, because some drives seem to have very poor
 * tolerance for latency during I/O.  For devices which don't suffer from
 * this problem (most don't), the unmask flag can be set using the "hdparm"
 * utility, to permit other interrupts during data/cmd transfers.
 */
void ide_do_request (ide_hwgroup_t *hwgroup)
{
	cli();	/* paranoia */
	if (hwgroup->handler != NULL) {
		printk("%s: EEeekk!! handler not NULL in ide_do_request()\n", hwgroup->hwif->name);
		return;
	}
	do {
		ide_hwif_t *hwif = hwgroup->hwif;
		struct request *rq;
		if ((rq = hwgroup->rq) == NULL) {
			if (hwif->sharing_irq && hwgroup->drive) /* set nIEN */
				OUT_BYTE(hwgroup->drive->ctl|2,hwif->ctl_port);
			/*
			 * hwgroup->next_hwif is different from hwgroup->hwif
			 * only when a request is inserted using "ide_next".
			 * This saves wear and tear on IDE tapes.
			 */
			hwif = hwgroup->next_hwif;
			do {
				rq = blk_dev[hwif->major].current_request;
				if (rq != NULL && rq->rq_status != RQ_INACTIVE)
					goto got_rq;
			} while ((hwif = hwif->next) != hwgroup->next_hwif);
			hwgroup->active = 0;
			return;		/* no work left for this hwgroup */
		}
	got_rq:
		do_request(hwgroup->hwif = hwgroup->next_hwif = hwif, hwgroup->rq = rq);
		cli();
	} while (hwgroup->handler == NULL);
}

/*
 * do_hwgroup_request() invokes ide_do_request() after first masking
 * all possible interrupts for the current hwgroup.  This prevents race
 * conditions in the event that an unexpected interrupt occurs while
 * we are in the driver.
 *
 * Note that when an interrupt is used to reenter the driver, the first level
 * handler will already have masked the irq that triggered, but any other ones
 * for the hwgroup will still be unmasked.  The driver tries to be careful
 * about such things.
 */
static void do_hwgroup_request (ide_hwgroup_t *hwgroup)
{
	if (hwgroup->handler == NULL) {
		ide_hwif_t *hgif = hwgroup->hwif;
		ide_hwif_t *hwif = hgif;
		hwgroup->active = 1;
		do {
			disable_irq(hwif->irq);
		} while ((hwif = hwif->next) != hgif);
		ide_do_request (hwgroup);
		do {
			enable_irq(hwif->irq);
		} while ((hwif = hwif->next) != hgif);
	}
}

static void do_ide0_request (void)	/* invoked with cli() */
{
	do_hwgroup_request (ide_hwifs[0].hwgroup);
}

#if MAX_HWIFS > 1
static void do_ide1_request (void)	/* invoked with cli() */
{
	do_hwgroup_request (ide_hwifs[1].hwgroup);
}
#endif

#if MAX_HWIFS > 2
static void do_ide2_request (void)	/* invoked with cli() */
{
	do_hwgroup_request (ide_hwifs[2].hwgroup);
}
#endif

#if MAX_HWIFS > 3
static void do_ide3_request (void)	/* invoked with cli() */
{
	do_hwgroup_request (ide_hwifs[3].hwgroup);
}
#endif

static void timer_expiry (unsigned long data)
{
	ide_hwgroup_t *hwgroup = (ide_hwgroup_t *) data;
	ide_drive_t   *drive   = hwgroup->drive;
	unsigned long flags;

	save_flags(flags);
	cli();

	if (hwgroup->poll_timeout != 0) { /* polling in progress? */
		ide_handler_t *handler = hwgroup->handler;
		hwgroup->handler = NULL;
		handler(drive);
	} else if (hwgroup->handler == NULL) {	 /* not waiting for anything? */
		sti(); /* drive must have responded just as the timer expired */
		printk("%s: marginal timeout\n", drive->name);
	} else {
		hwgroup->handler = NULL;	/* abort the operation */
		if (hwgroup->hwif->dmaproc)
			(void) hwgroup->hwif->dmaproc (ide_dma_abort, drive);
		ide_error(drive, "irq timeout", GET_STAT());
	}
	if (hwgroup->handler == NULL)
		do_hwgroup_request (hwgroup);
	restore_flags(flags);
}

/*
 * There's nothing really useful we can do with an unexpected interrupt,
 * other than reading the status register (to clear it), and logging it.
 * There should be no way that an irq can happen before we're ready for it,
 * so we needn't worry much about losing an "important" interrupt here.
 *
 * On laptops (and "green" PCs), an unexpected interrupt occurs whenever the
 * drive enters "idle", "standby", or "sleep" mode, so if the status looks
 * "good", we just ignore the interrupt completely.
 *
 * This routine assumes cli() is in effect when called.
 *
 * If an unexpected interrupt happens on irq15 while we are handling irq14
 * and if the two interfaces are "serialized" (CMD640), then it looks like
 * we could screw up by interfering with a new request being set up for irq15.
 *
 * In reality, this is a non-issue.  The new command is not sent unless the
 * drive is ready to accept one, in which case we know the drive is not
 * trying to interrupt us.  And ide_set_handler() is always invoked before
 * completing the issuance of any new drive command, so we will not be
 * accidently invoked as a result of any valid command completion interrupt.
 *
 */
static void unexpected_intr (int irq, ide_hwgroup_t *hwgroup)
{
	byte stat;
	unsigned int unit;
	ide_hwif_t *hwif = hwgroup->hwif;

	/*
	 * handle the unexpected interrupt
	 */
	do {
		if (hwif->irq == irq) {
			for (unit = 0; unit < MAX_DRIVES; ++unit) {
				ide_drive_t *drive = &hwif->drives[unit];
				if (!drive->present)
					continue;
				SELECT_DRIVE(hwif,drive);
				udelay(100);  /* Ugly, but wait_stat() may not be safe here */
				if (!OK_STAT(stat=GET_STAT(), drive->ready_stat, BAD_STAT)) {
					/* Try to not flood the console with msgs */
					static unsigned long last_msgtime = 0;
					if ((last_msgtime + (HZ/2)) < jiffies) {
						last_msgtime = jiffies;
						(void) ide_dump_status(drive, "unexpected_intr", stat);
					}
				}
				if ((stat & DRQ_STAT))
					try_to_flush_leftover_data(drive);
			}
		}
	} while ((hwif = hwif->next) != hwgroup->hwif);
	SELECT_DRIVE(hwif,hwgroup->drive); /* Ugh.. probably interrupts current I/O */
	udelay(100);  /* Ugly, but wait_stat() may not be safe here */
}

/*
 * entry point for all interrupts, caller does cli() for us
 */
void ide_intr (int irq, void *dev_id, struct pt_regs *regs)
{
	ide_hwgroup_t *hwgroup = dev_id;
	ide_handler_t *handler;

	if (irq == hwgroup->hwif->irq && (handler = hwgroup->handler) != NULL) {
		ide_drive_t *drive = hwgroup->drive;
		hwgroup->handler = NULL;
		del_timer(&(hwgroup->timer));
		if (drive->unmask)
			sti();
		handler(drive);
		cli();	/* this is necessary, as next rq may be different irq */
		if (hwgroup->handler == NULL) {
			SET_RECOVERY_TIMER(HWIF(drive));
 			ide_do_request(hwgroup);
		}
	} else {
		unexpected_intr(irq, hwgroup);
	}
	cli();
}

/*
 * get_info_ptr() returns the (ide_drive_t *) for a given device number.
 * It returns NULL if the given device number does not match any present drives.
 */
static ide_drive_t *get_info_ptr (kdev_t i_rdev)
{
	int		major = MAJOR(i_rdev);
	unsigned int	h;

	for (h = 0; h < MAX_HWIFS; ++h) {
		ide_hwif_t  *hwif = &ide_hwifs[h];
		if (hwif->present && major == hwif->major) {
			unsigned unit = DEVICE_NR(i_rdev);
			if (unit < MAX_DRIVES) {
				ide_drive_t *drive = &hwif->drives[unit];
				if (drive->present)
					return drive;
			} else if (major == IDE0_MAJOR && unit < 4) {
				printk("ide: probable bad entry for /dev/hd%c\n", 'a'+unit);
				printk("ide: to fix it, run:  /usr/src/linux/scripts/MAKEDEV.ide\n");
			}
			break;
		}
	}
	return NULL;
}

/*
 * This function is intended to be used prior to invoking ide_do_drive_cmd().
 */
void ide_init_drive_cmd (struct request *rq)
{
	rq->buffer = NULL;
	rq->cmd = IDE_DRIVE_CMD;
	rq->sector = 0;
	rq->nr_sectors = 0;
	rq->current_nr_sectors = 0;
	rq->sem = NULL;
	rq->bh = NULL;
	rq->bhtail = NULL;
	rq->next = NULL;

#if 0	/* these are done each time through ide_do_drive_cmd() */
	rq->errors = 0;
	rq->rq_status = RQ_ACTIVE;
	rq->rq_dev = ????;
#endif
}

/*
 * This function issues a special IDE device request
 * onto the request queue.
 *
 * If action is ide_wait, then the rq is queued at the end of the
 * request queue, and the function sleeps until it has been processed.
 * This is for use when invoked from an ioctl handler.
 *
 * If action is ide_preempt, then the rq is queued at the head of
 * the request queue, displacing the currently-being-processed
 * request and this function returns immediately without waiting
 * for the new rq to be completed.  This is VERY DANGEROUS, and is
 * intended for careful use by the ATAPI tape/cdrom driver code.
 *
 * If action is ide_next, then the rq is queued immediately after
 * the currently-being-processed-request (if any), and the function
 * returns without waiting for the new rq to be completed.  As above,
 * This is VERY DANGEROUS, and is intended for careful use by the
 * ATAPI tape/cdrom driver code.
 *
 * If action is ide_end, then the rq is queued at the end of the
 * request queue, and the function returns immediately without waiting
 * for the new rq to be completed. This is again intended for careful
 * use by the ATAPI tape/cdrom driver code. (Currently used by ide-tape.c,
 * when operating in the pipelined operation mode).
 */
int ide_do_drive_cmd (ide_drive_t *drive, struct request *rq, ide_action_t action)
{
	unsigned long flags;
	unsigned int major = HWIF(drive)->major;
	struct request *cur_rq;
	struct blk_dev_struct *bdev = &blk_dev[major];
	struct semaphore sem = MUTEX_LOCKED;

	if (IS_PROMISE_DRIVE && rq->buffer != NULL)
		return -ENOSYS;  /* special drive cmds not supported */
	rq->errors = 0;
	rq->rq_status = RQ_ACTIVE;
	rq->rq_dev = MKDEV(major,(drive->select.b.unit)<<PARTN_BITS);
	if (action == ide_wait)
		rq->sem = &sem;
	unplug_device(bdev);

	save_flags(flags);
	cli();
	if (action == ide_next)
		HWGROUP(drive)->next_hwif = HWIF(drive);
	cur_rq = bdev->current_request;

	if (cur_rq == NULL || action == ide_preempt) {
		rq->next = cur_rq;
		bdev->current_request = rq;
		if (action == ide_preempt)
			HWGROUP(drive)->rq = NULL;
	} else {
		if (action == ide_wait || action == ide_end) {
			while (cur_rq->next != NULL)	/* find end of list */
				cur_rq = cur_rq->next;
		}
		rq->next = cur_rq->next;
		cur_rq->next = rq;
	}
	if (!HWGROUP(drive)->active) {
		do_hwgroup_request(HWGROUP(drive));
		cli();
	}
	if (action == ide_wait  && rq->rq_status != RQ_INACTIVE)
		down(&sem);	/* wait for it to be serviced */
	restore_flags(flags);
	return rq->errors ? -EIO : 0;	/* return -EIO if errors */
}

static int ide_open(struct inode * inode, struct file * filp)
{
	ide_dr