hd.c

linux 内核源代码

{
	struct request *req = CURRENT;
	if (req != NULL) {
		struct hd_i_struct *disk = req->rq_disk->private_data;
		if (++req->errors >= MAX_ERRORS || (hd_error & BBD_ERR)) {
			end_request(req, 0);
			disk->special_op = disk->recalibrate = 1;
		} else if (req->errors % RESET_FREQ == 0)
			reset = 1;
		else if ((hd_error & TRK0_ERR) || req->errors % RECAL_FREQ == 0)
			disk->special_op = disk->recalibrate = 1;
		/* Otherwise just retry */
	}
}

static inline int wait_DRQ(void)
{
	int retries = 100000, stat;

	while (--retries > 0)
		if ((stat = inb_p(HD_STATUS)) & DRQ_STAT)
			return 0;
	dump_status("wait_DRQ", stat);
	return -1;
}

static void read_intr(void)
{
	struct request *req;
	int i, retries = 100000;

	do {
		i = (unsigned) inb_p(HD_STATUS);
		if (i & BUSY_STAT)
			continue;
		if (!OK_STATUS(i))
			break;
		if (i & DRQ_STAT)
			goto ok_to_read;
	} while (--retries > 0);
	dump_status("read_intr", i);
	bad_rw_intr();
	hd_request();
	return;
ok_to_read:
	req = CURRENT;
	insw(HD_DATA,req->buffer,256);
	req->sector++;
	req->buffer += 512;
	req->errors = 0;
	i = --req->nr_sectors;
	--req->current_nr_sectors;
#ifdef DEBUG
	printk("%s: read: sector %ld, remaining = %ld, buffer=%p\n",
		req->rq_disk->disk_name, req->sector, req->nr_sectors,
		req->buffer+512);
#endif
	if (req->current_nr_sectors <= 0)
		end_request(req, 1);
	if (i > 0) {
		SET_HANDLER(&read_intr);
		return;
	}
	(void) inb_p(HD_STATUS);
#if (HD_DELAY > 0)
	last_req = read_timer();
#endif
	if (elv_next_request(QUEUE))
		hd_request();
	return;
}

static void write_intr(void)
{
	struct request *req = CURRENT;
	int i;
	int retries = 100000;

	do {
		i = (unsigned) inb_p(HD_STATUS);
		if (i & BUSY_STAT)
			continue;
		if (!OK_STATUS(i))
			break;
		if ((req->nr_sectors <= 1) || (i & DRQ_STAT))
			goto ok_to_write;
	} while (--retries > 0);
	dump_status("write_intr", i);
	bad_rw_intr();
	hd_request();
	return;
ok_to_write:
	req->sector++;
	i = --req->nr_sectors;
	--req->current_nr_sectors;
	req->buffer += 512;
	if (!i || (req->bio && req->current_nr_sectors <= 0))
		end_request(req, 1);
	if (i > 0) {
		SET_HANDLER(&write_intr);
		outsw(HD_DATA,req->buffer,256);
		local_irq_enable();
	} else {
#if (HD_DELAY > 0)
		last_req = read_timer();
#endif
		hd_request();
	}
	return;
}

static void recal_intr(void)
{
	check_status();
#if (HD_DELAY > 0)
	last_req = read_timer();
#endif
	hd_request();
}

/*
 * This is another of the error-routines I don't know what to do with. The
 * best idea seems to just set reset, and start all over again.
 */
static void hd_times_out(unsigned long dummy)
{
	char *name;

	do_hd = NULL;

	if (!CURRENT)
		return;

	disable_irq(HD_IRQ);
	local_irq_enable();
	reset = 1;
	name = CURRENT->rq_disk->disk_name;
	printk("%s: timeout\n", name);
	if (++CURRENT->errors >= MAX_ERRORS) {
#ifdef DEBUG
		printk("%s: too many errors\n", name);
#endif
		end_request(CURRENT, 0);
	}
	local_irq_disable();
	hd_request();
	enable_irq(HD_IRQ);
}

static int do_special_op(struct hd_i_struct *disk, struct request *req)
{
	if (disk->recalibrate) {
		disk->recalibrate = 0;
		hd_out(disk,disk->sect,0,0,0,WIN_RESTORE,&recal_intr);
		return reset;
	}
	if (disk->head > 16) {
		printk ("%s: cannot handle device with more than 16 heads - giving up\n", req->rq_disk->disk_name);
		end_request(req, 0);
	}
	disk->special_op = 0;
	return 1;
}

/*
 * The driver enables interrupts as much as possible.  In order to do this,
 * (a) the device-interrupt is disabled before entering hd_request(),
 * and (b) the timeout-interrupt is disabled before the sti().
 *
 * 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. The IDE driver has support to unmask
 * interrupts for non-broken hardware, so use that driver if required.
 */
static void hd_request(void)
{
	unsigned int block, nsect, sec, track, head, cyl;
	struct hd_i_struct *disk;
	struct request *req;

	if (do_hd)
		return;
repeat:
	del_timer(&device_timer);
	local_irq_enable();

	req = CURRENT;
	if (!req) {
		do_hd = NULL;
		return;
	}

	if (reset) {
		local_irq_disable();
		reset_hd();
		return;
	}
	disk = req->rq_disk->private_data;
	block = req->sector;
	nsect = req->nr_sectors;
	if (block >= get_capacity(req->rq_disk) ||
	    ((block+nsect) > get_capacity(req->rq_disk))) {
		printk("%s: bad access: block=%d, count=%d\n",
			req->rq_disk->disk_name, block, nsect);
		end_request(req, 0);
		goto repeat;
	}

	if (disk->special_op) {
		if (do_special_op(disk, req))
			goto repeat;
		return;
	}
	sec   = block % disk->sect + 1;
	track = block / disk->sect;
	head  = track % disk->head;
	cyl   = track / disk->head;
#ifdef DEBUG
	printk("%s: %sing: CHS=%d/%d/%d, sectors=%d, buffer=%p\n",
		req->rq_disk->disk_name,
		req_data_dir(req) == READ ? "read" : "writ",
		cyl, head, sec, nsect, req->buffer);
#endif
	if (blk_fs_request(req)) {
		switch (rq_data_dir(req)) {
		case READ:
			hd_out(disk,nsect,sec,head,cyl,WIN_READ,&read_intr);
			if (reset)
				goto repeat;
			break;
		case WRITE:
			hd_out(disk,nsect,sec,head,cyl,WIN_WRITE,&write_intr);
			if (reset)
				goto repeat;
			if (wait_DRQ()) {
				bad_rw_intr();
				goto repeat;
			}
			outsw(HD_DATA,req->buffer,256);
			break;
		default:
			printk("unknown hd-command\n");
			end_request(req, 0);
			break;
		}
	}
}

static void do_hd_request (struct request_queue * q)
{
	disable_irq(HD_IRQ);
	hd_request();
	enable_irq(HD_IRQ);
}

static int hd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
	struct hd_i_struct *disk = bdev->bd_disk->private_data;

	geo->heads = disk->head;
	geo->sectors = disk->sect;
	geo->cylinders = disk->cyl;
	return 0;
}

/*
 * Releasing a block device means we sync() it, so that it can safely
 * be forgotten about...
 */

static irqreturn_t hd_interrupt(int irq, void *dev_id)
{
	void (*handler)(void) = do_hd;

	do_hd = NULL;
	del_timer(&device_timer);
	if (!handler)
		handler = unexpected_hd_interrupt;
	handler();
	local_irq_enable();
	return IRQ_HANDLED;
}

static struct block_device_operations hd_fops = {
	.getgeo =	hd_getgeo,
};

/*
 * This is the hard disk IRQ description. The IRQF_DISABLED in sa_flags
 * means we run the IRQ-handler with interrupts disabled:  this is bad for
 * interrupt latency, but anything else has led to problems on some
 * machines.
 *
 * We enable interrupts in some of the routines after making sure it's
 * safe.
 */

static int __init hd_init(void)
{
	int drive;

	if (register_blkdev(MAJOR_NR,"hd"))
		return -1;

	hd_queue = blk_init_queue(do_hd_request, &hd_lock);
	if (!hd_queue) {
		unregister_blkdev(MAJOR_NR,"hd");
		return -ENOMEM;
	}

	blk_queue_max_sectors(hd_queue, 255);
	init_timer(&device_timer);
	device_timer.function = hd_times_out;
	blk_queue_hardsect_size(hd_queue, 512);

	if (!NR_HD) {
		/*
		 * We don't know anything about the drive.  This means
		 * that you *MUST* specify the drive parameters to the
		 * kernel yourself.
		 *
		 * If we were on an i386, we used to read this info from
		 * the BIOS or CMOS.  This doesn't work all that well,
		 * since this assumes that this is a primary or secondary
		 * drive, and if we're using this legacy driver, it's
		 * probably an auxilliary controller added to recover
		 * legacy data off an ST-506 drive.  Either way, it's
		 * definitely safest to have the user explicitly specify
		 * the information.
		 */
		printk("hd: no drives specified - use hd=cyl,head,sectors"
			" on kernel command line\n");
		goto out;
	}

	for (drive=0 ; drive < NR_HD ; drive++) {
		struct gendisk *disk = alloc_disk(64);
		struct hd_i_struct *p = &hd_info[drive];
		if (!disk)
			goto Enomem;
		disk->major = MAJOR_NR;
		disk->first_minor = drive << 6;
		disk->fops = &hd_fops;
		sprintf(disk->disk_name, "hd%c", 'a'+drive);
		disk->private_data = p;
		set_capacity(disk, p->head * p->sect * p->cyl);
		disk->queue = hd_queue;
		p->unit = drive;
		hd_gendisk[drive] = disk;
		printk ("%s: %luMB, CHS=%d/%d/%d\n",
			disk->disk_name, (unsigned long)get_capacity(disk)/2048,
			p->cyl, p->head, p->sect);
	}

	if (request_irq(HD_IRQ, hd_interrupt, IRQF_DISABLED, "hd", NULL)) {
		printk("hd: unable to get IRQ%d for the hard disk driver\n",
			HD_IRQ);
		goto out1;
	}
	if (!request_region(HD_DATA, 8, "hd")) {
		printk(KERN_WARNING "hd: port 0x%x busy\n", HD_DATA);
		goto out2;
	}
	if (!request_region(HD_CMD, 1, "hd(cmd)")) {
		printk(KERN_WARNING "hd: port 0x%x busy\n", HD_CMD);
		goto out3;
	}

	/* Let them fly */
	for(drive=0; drive < NR_HD; drive++)
		add_disk(hd_gendisk[drive]);

	return 0;

out3:
	release_region(HD_DATA, 8);
out2:
	free_irq(HD_IRQ, NULL);
out1:
	for (drive = 0; drive < NR_HD; drive++)
		put_disk(hd_gendisk[drive]);
	NR_HD = 0;
out:
	del_timer(&device_timer);
	unregister_blkdev(MAJOR_NR,"hd");
	blk_cleanup_queue(hd_queue);
	return -1;
Enomem:
	while (drive--)
		put_disk(hd_gendisk[drive]);
	goto out;
}

static int __init parse_hd_setup (char *line) {
	int ints[6];

	(void) get_options(line, ARRAY_SIZE(ints), ints);
	hd_setup(NULL, ints);

	return 1;
}
__setup("hd=", parse_hd_setup);

module_init(hd_init);