ide.c

讲述linux的初始化过程

#if FANCY_STATUS_DUMPS
	printk(" { ");
	if (stat & BUSY_STAT)
		printk("Busy ");
	else {
		if (stat & READY_STAT)	printk("DriveReady ");
		if (stat & WRERR_STAT)	printk("DeviceFault ");
		if (stat & SEEK_STAT)	printk("SeekComplete ");
		if (stat & DRQ_STAT)	printk("DataRequest ");
		if (stat & ECC_STAT)	printk("CorrectedError ");
		if (stat & INDEX_STAT)	printk("Index ");
		if (stat & ERR_STAT)	printk("Error ");
	}
	printk("}");
#endif	/* FANCY_STATUS_DUMPS */
	printk("\n");
	if ((stat & (BUSY_STAT|ERR_STAT)) == ERR_STAT) {
		err = GET_ERR();
		printk("%s: %s: error=0x%02x", drive->name, msg, err);
#if FANCY_STATUS_DUMPS
		if (drive->media == ide_disk) {
			printk(" { ");
			if (err & ABRT_ERR)	printk("DriveStatusError ");
			if (err & ICRC_ERR)	printk("%s", (err & ABRT_ERR) ? "BadCRC " : "BadSector ");
			if (err & ECC_ERR)	printk("UncorrectableError ");
			if (err & ID_ERR)	printk("SectorIdNotFound ");
			if (err & TRK0_ERR)	printk("TrackZeroNotFound ");
			if (err & MARK_ERR)	printk("AddrMarkNotFound ");
			printk("}");
			if ((err & (BBD_ERR | ABRT_ERR)) == BBD_ERR || (err & (ECC_ERR|ID_ERR|MARK_ERR))) {
				byte cur = IN_BYTE(IDE_SELECT_REG);
				if (cur & 0x40) {	/* using LBA? */
					printk(", LBAsect=%ld", (unsigned long)
					 ((cur&0xf)<<24)
					 |(IN_BYTE(IDE_HCYL_REG)<<16)
					 |(IN_BYTE(IDE_LCYL_REG)<<8)
					 | IN_BYTE(IDE_SECTOR_REG));
				} else {
					printk(", CHS=%d/%d/%d",
					 (IN_BYTE(IDE_HCYL_REG)<<8) +
					  IN_BYTE(IDE_LCYL_REG),
					  cur & 0xf,
					  IN_BYTE(IDE_SECTOR_REG));
				}
				if (HWGROUP(drive)->rq)
					printk(", sector=%ld", HWGROUP(drive)->rq->sector);
			}
		}
#endif	/* FANCY_STATUS_DUMPS */
		printk("\n");
	}
	__restore_flags (flags);	/* local CPU only */
	return err;
}

/*
 * try_to_flush_leftover_data() is invoked in response to a drive
 * unexpectedly having its DRQ_STAT bit set.  As an alternative to
 * resetting the drive, this routine tries to clear the condition
 * by read a sector's worth of data from the drive.  Of course,
 * this may not help if the drive is *waiting* for data from *us*.
 */
static void try_to_flush_leftover_data (ide_drive_t *drive)
{
	int i = (drive->mult_count ? drive->mult_count : 1) * SECTOR_WORDS;

	if (drive->media != ide_disk)
		return;
	while (i > 0) {
		u32 buffer[16];
		unsigned int wcount = (i > 16) ? 16 : i;
		i -= wcount;
		ide_input_data (drive, buffer, wcount);
	}
}

/*
 * ide_error() takes action based on the error returned by the drive.
 */
ide_startstop_t ide_error (ide_drive_t *drive, const char *msg, byte stat)
{
	struct request *rq;
	byte err;

	err = ide_dump_status(drive, msg, stat);
	if (drive == NULL || (rq = HWGROUP(drive)->rq) == NULL)
		return ide_stopped;
	/* retry only "normal" I/O: */
	if (rq->cmd == IDE_DRIVE_CMD || rq->cmd == IDE_DRIVE_TASK) {
		rq->errors = 1;
		ide_end_drive_cmd(drive, stat, err);
		return ide_stopped;
	}
	if (stat & BUSY_STAT || ((stat & WRERR_STAT) && !drive->nowerr)) { /* other bits are useless when BUSY */
		rq->errors |= ERROR_RESET;
	} else {
		if (drive->media == ide_disk && (stat & ERR_STAT)) {
			/* err has different meaning on cdrom and tape */
			if (err == ABRT_ERR) {
				if (drive->select.b.lba && IN_BYTE(IDE_COMMAND_REG) == WIN_SPECIFY)
					return ide_stopped; /* some newer drives don't support WIN_SPECIFY */
			} else if ((err & (ABRT_ERR | ICRC_ERR)) == (ABRT_ERR | ICRC_ERR)) {
				drive->crc_count++; /* UDMA crc error -- just retry the operation */
			} else if (err & (BBD_ERR | ECC_ERR))	/* retries won't help these */
				rq->errors = ERROR_MAX;
			else if (err & TRK0_ERR)	/* help it find track zero */
				rq->errors |= ERROR_RECAL;
		}
		if ((stat & DRQ_STAT) && rq->cmd != WRITE)
			try_to_flush_leftover_data(drive);
	}
	if (GET_STAT() & (BUSY_STAT|DRQ_STAT))
		OUT_BYTE(WIN_IDLEIMMEDIATE,IDE_COMMAND_REG);	/* force an abort */

	if (rq->errors >= ERROR_MAX) {
		if (drive->driver != NULL)
			DRIVER(drive)->end_request(0, HWGROUP(drive));
		else
	 		ide_end_request(0, HWGROUP(drive));
	} else {
		if ((rq->errors & ERROR_RESET) == ERROR_RESET) {
			++rq->errors;
			return ide_do_reset(drive);
		}
		if ((rq->errors & ERROR_RECAL) == ERROR_RECAL)
			drive->special.b.recalibrate = 1;
		++rq->errors;
	}
	return ide_stopped;
}

/*
 * Issue a simple drive command
 * The drive must be selected beforehand.
 */
void ide_cmd (ide_drive_t *drive, byte cmd, byte nsect, ide_handler_t *handler)
{
	ide_set_handler (drive, handler, WAIT_CMD, NULL);
	if (IDE_CONTROL_REG)
		OUT_BYTE(drive->ctl,IDE_CONTROL_REG);	/* clear nIEN */
	SELECT_MASK(HWIF(drive),drive,0);
	OUT_BYTE(nsect,IDE_NSECTOR_REG);
	OUT_BYTE(cmd,IDE_COMMAND_REG);
}

/*
 * drive_cmd_intr() is invoked on completion of a special DRIVE_CMD.
 */
static ide_startstop_t drive_cmd_intr (ide_drive_t *drive)
{
	struct request *rq = HWGROUP(drive)->rq;
	byte *args = (byte *) rq->buffer;
	byte stat = GET_STAT();
	int retries = 10;

	ide__sti();	/* local CPU only */
	if ((stat & DRQ_STAT) && args && args[3]) {
		byte io_32bit = drive->io_32bit;
		drive->io_32bit = 0;
		ide_input_data(drive, &args[4], args[3] * SECTOR_WORDS);
		drive->io_32bit = io_32bit;
		while (((stat = GET_STAT()) & BUSY_STAT) && retries--)
			udelay(100);
	}

	if (!OK_STAT(stat, READY_STAT, BAD_STAT))
		return ide_error(drive, "drive_cmd", stat); /* calls ide_end_drive_cmd */
	ide_end_drive_cmd (drive, stat, GET_ERR());
	return ide_stopped;
}

/*
 * do_special() is used to issue WIN_SPECIFY, WIN_RESTORE, and WIN_SETMULT
 * commands to a drive.  It used to do much more, but has been scaled back.
 */
static ide_startstop_t do_special (ide_drive_t *drive)
{
	special_t *s = &drive->special;

#ifdef DEBUG
	printk("%s: do_special: 0x%02x\n", drive->name, s->all);
#endif
	if (s->b.set_tune) {
		ide_tuneproc_t *tuneproc = HWIF(drive)->tuneproc;
		s->b.set_tune = 0;
		if (tuneproc != NULL)
			tuneproc(drive, drive->tune_req);
	} else if (drive->driver != NULL) {
		return DRIVER(drive)->special(drive);
	} else if (s->all) {
		printk("%s: bad special flag: 0x%02x\n", drive->name, s->all);
		s->all = 0;
	}
	return ide_stopped;
}

/*
 * This routine busy-waits for the drive status to be not "busy".
 * It then checks the status for all of the "good" bits and none
 * of the "bad" bits, and if all is okay it returns 0.  All other
 * cases return 1 after invoking ide_error() -- caller should just return.
 *
 * This routine should get fixed to not hog the cpu during extra long waits..
 * That could be done by busy-waiting for the first jiffy or two, and then
 * setting a timer to wake up at half second intervals thereafter,
 * until timeout is achieved, before timing out.
 */
int ide_wait_stat (ide_startstop_t *startstop, ide_drive_t *drive, byte good, byte bad, unsigned long timeout) {
	byte stat;
	int i;
	unsigned long flags;
 
	udelay(1);	/* spec allows drive 400ns to assert "BUSY" */
	if ((stat = GET_STAT()) & BUSY_STAT) {
		__save_flags(flags);	/* local CPU only */
		ide__sti();		/* local CPU only */
		timeout += jiffies;
		while ((stat = GET_STAT()) & BUSY_STAT) {
			if (0 < (signed long)(jiffies - timeout)) {
				__restore_flags(flags);	/* local CPU only */
				*startstop = ide_error(drive, "status timeout", stat);
				return 1;
			}
		}
		__restore_flags(flags);	/* local CPU only */
	}
	/*
	 * Allow status to settle, then read it again.
	 * A few rare drives vastly violate the 400ns spec here,
	 * so we'll wait up to 10usec for a "good" status
	 * rather than expensively fail things immediately.
	 * This fix courtesy of Matthew Faupel & Niccolo Rigacci.
	 */
	for (i = 0; i < 10; i++) {
		udelay(1);
		if (OK_STAT((stat = GET_STAT()), good, bad))
			return 0;
	}
	*startstop = ide_error(drive, "status error", stat);
	return 1;
}

/*
 * execute_drive_cmd() issues a special drive command,
 * usually initiated by ioctl() from the external hdparm program.
 */
static ide_startstop_t execute_drive_cmd (ide_drive_t *drive, struct request *rq)
{
	byte *args = rq->buffer;
	if (args && rq->cmd == IDE_DRIVE_TASK) {
		byte sel;
#ifdef DEBUG
		printk("%s: DRIVE_TASK_CMD data=x%02x cmd=0x%02x fr=0x%02x ns=0x%02x sc=0x%02x lcyl=0x%02x hcyl=0x%02x sel=0x%02x\n",
			drive->name, args[0], args[1], args[2], args[3], args[4], args[5], args[6]);
#endif
		OUT_BYTE(args[1], IDE_FEATURE_REG);
		OUT_BYTE(args[3], IDE_SECTOR_REG);
		OUT_BYTE(args[4], IDE_LCYL_REG);
		OUT_BYTE(args[5], IDE_HCYL_REG);
		sel = (args[6] & ~0x10);
		if (drive->select.b.unit)
			sel |= 0x10;
		OUT_BYTE(sel, IDE_SELECT_REG);
		ide_cmd(drive, args[0], args[2], &drive_cmd_intr);
		return ide_started;
	} else if (args) {
#ifdef DEBUG
		printk("%s: DRIVE_CMD cmd=0x%02x sc=0x%02x fr=0x%02x xx=0x%02x\n",
		 drive->name, args[0], args[1], args[2], args[3]);
#endif
		if (args[0] == WIN_SMART) {
			OUT_BYTE(0x4f, IDE_LCYL_REG);
			OUT_BYTE(0xc2, IDE_HCYL_REG);
			OUT_BYTE(args[2],IDE_FEATURE_REG);
			OUT_BYTE(args[1],IDE_SECTOR_REG);
			ide_cmd(drive, args[0], args[3], &drive_cmd_intr);
			return ide_started;
		}
		OUT_BYTE(args[2],IDE_FEATURE_REG);
		ide_cmd(drive, args[0], args[1], &drive_cmd_intr);
		return ide_started;
	} else {
		/*
		 * NULL is actually a valid way of waiting for
		 * all current requests to be flushed from the queue.
		 */
#ifdef DEBUG
		printk("%s: DRIVE_CMD (null)\n", drive->name);
#endif
		ide_end_drive_cmd(drive, GET_STAT(), GET_ERR());
		return ide_stopped;
	}
}

/*
 * start_request() initiates handling of a new I/O request
 */
static ide_startstop_t start_request (ide_drive_t *drive)
{
	ide_startstop_t startstop;
	unsigned long block, blockend;
	struct request *rq = blkdev_entry_next_request(&drive->queue.queue_head);
	unsigned int minor = MINOR(rq->rq_dev), unit = minor >> PARTN_BITS;
	ide_hwif_t *hwif = HWIF(drive);

#ifdef DEBUG
	printk("%s: start_request: current=0x%08lx\n", hwif->name, (unsigned long) rq);
#endif
	if (unit >= MAX_DRIVES) {
		printk("%s: bad device number: %s\n", hwif->name, kdevname(rq->rq_dev));
		goto kill_rq;
	}
#ifdef DEBUG
	if (rq->bh && !buffer_locked(rq->bh)) {
		printk("%s: block not locked\n", drive->name);
		goto kill_rq;
	}
#endif
	block    = rq->sector;
	blockend = block + rq->nr_sectors;

	if ((rq->cmd == READ || rq->cmd == WRITE) &&
	    (drive->media == ide_disk || drive->media == ide_floppy)) {
		if ((blockend < block) || (blockend > drive->part[minor&PARTN_MASK].nr_sects)) {
			printk("%s%c: bad access: block=%ld, count=%ld\n", drive->name,
			 (minor&PARTN_MASK)?'0'+(minor&PARTN_MASK):' ', block, rq->nr_sectors);
			goto kill_rq;
		}
		block += drive->part[minor&PARTN_MASK].start_sect + drive->sect0;
	}
	/* Yecch - this will shift the entire interval,
	   possibly killing some innocent following sector */
	if (block == 0 && drive->remap_0_to_1 == 1)
		block = 1;  /* redirect MBR access to EZ-Drive partn table */

#if (DISK_RECOVERY_TIME > 0)
	while ((read_timer() - hwif->last_time) < DISK_RECOVERY_TIME);
#endif

	SELECT_DRIVE(hwif, drive);
	if (ide_wait_stat(&startstop, drive, drive->ready_stat, BUSY_STAT|DRQ_STAT, WAIT_READY)) {
		printk("%s: drive not ready for command\n", drive->name);
		return startstop;
	}
	if (!drive->special.all) {
		if (rq->cmd == IDE_DRIVE_CMD || rq->cmd == IDE_DRIVE_TASK) {
			return execute_drive_cmd(drive, rq);
		}
		if (drive->driver != NULL) {
			return (DRIVER(drive)->do_request(drive, rq, block));
		}
		printk("%s: media type %d not supported\n", drive->name, drive->media);
		goto kill_rq;
	}
	return do_special(drive);
kill_rq:
	if (drive->driver != NULL)
		DRIVER(drive)->end_request(0, HWGROUP(drive));
	else
		ide_end_request(0, HWGROUP(drive));
	return ide_stopped;
}

/*
 * ide_stall_queue() can be used by a drive to give excess bandwidth back
 * to the hwgroup by sleeping for timeout jiffies.
 */
void ide_stall_queue (ide_drive_t *drive, unsigned long timeout)
{
	if (timeout > WAIT_WORSTCASE)
		timeout = WAIT_WORSTCASE;
	drive->sleep = timeout + jiffies;
}

#define WAKEUP(drive)	((drive)->service_start + 2 * (drive)->service_time)

/*
 * choose_drive() selects the next drive which will be serviced.
 */
static inline ide_drive_t *choose_drive (ide_hwgroup_t *hwgroup)
{
	ide_drive_t *drive, *best;

repeat:	
	best = NULL;
	drive = hwgroup->drive;
	do {
		if (!list_empty(&drive->queue.queue_head) && (!drive->sleep || 0 <= (signed long)(jiffies - drive->sleep))) {
			if (!best
			 || (drive->sleep && (!best->sleep || 0 < (signed long)(best->sleep - drive->sleep)))
			 || (!best->sleep && 0 < (signed long)(WAKEUP(best) - WAKEUP(drive))))
			{
				if( !drive->queue.plugged )
					best = drive;
			}
		}
	} while ((drive = drive->next) != hwgroup->drive);
	if (best && best->nice1 && !best->sleep && best != hwgroup->drive && best->service_time > WAIT_MIN_SLEEP) {
		long t = (signed long)(WAKEUP(best) - jiffies);
		if (t >= WAIT_MIN_SLEEP) {
			/*
			 * We *may* have some time to spare, but first let's see if
			 * someone can potentially benefit from our nice mood today..
			 */
			drive = best->next;
			do {
				if (!drive->sleep
				 && 0 < (signed long)(WAKEUP(drive) - (jiffies - best->service_time))
				 && 0 < (signed long)((jiffies + t) - WAKEUP(drive)))
				{
					ide_stall_queue(best, IDE_MIN(t, 10 * WAIT_MIN_SLEEP));
					goto repeat;
				}
			} while ((drive = drive->next) != best);
		}
	}
	return best;