floppy.c

Linux块设备驱动源码

static void scandrives(void)
{
	int i, drive, saved_drive;

	if (DP->select_delay)
		return;

	saved_drive = current_drive;
	for (i = 0; i < N_DRIVE; i++) {
		drive = (saved_drive + i + 1) % N_DRIVE;
		if (UDRS->fd_ref == 0 || UDP->select_delay != 0)
			continue;	/* skip closed drives */
		set_fdc(drive);
		if (!(set_dor(fdc, ~3, UNIT(drive) | (0x10 << UNIT(drive))) &
		      (0x10 << UNIT(drive))))
			/* switch the motor off again, if it was off to
			 * begin with */
			set_dor(fdc, ~(0x10 << UNIT(drive)), 0);
	}
	set_fdc(saved_drive);
}

static void empty(void)
{
}

static DECLARE_WORK(floppy_work, NULL, NULL);

static void schedule_bh(void (*handler) (void))
{
	PREPARE_WORK(&floppy_work, (void (*)(void *))handler, NULL);
	schedule_work(&floppy_work);
}

static DEFINE_TIMER(fd_timer, NULL, 0, 0);

static void cancel_activity(void)
{
	unsigned long flags;

	spin_lock_irqsave(&floppy_lock, flags);
	do_floppy = NULL;
	PREPARE_WORK(&floppy_work, (void *)empty, NULL);
	del_timer(&fd_timer);
	spin_unlock_irqrestore(&floppy_lock, flags);
}

/* this function makes sure that the disk stays in the drive during the
 * transfer */
static void fd_watchdog(void)
{
#ifdef DCL_DEBUG
	if (DP->flags & FD_DEBUG) {
		DPRINT("calling disk change from watchdog\n");
	}
#endif

	if (disk_change(current_drive)) {
		DPRINT("disk removed during i/o\n");
		cancel_activity();
		cont->done(0);
		reset_fdc();
	} else {
		del_timer(&fd_timer);
		fd_timer.function = (timeout_fn) fd_watchdog;
		fd_timer.expires = jiffies + HZ / 10;
		add_timer(&fd_timer);
	}
}

static void main_command_interrupt(void)
{
	del_timer(&fd_timer);
	cont->interrupt();
}

/* waits for a delay (spinup or select) to pass */
static int fd_wait_for_completion(unsigned long delay, timeout_fn function)
{
	if (FDCS->reset) {
		reset_fdc();	/* do the reset during sleep to win time
				 * if we don't need to sleep, it's a good
				 * occasion anyways */
		return 1;
	}

	if ((signed)(jiffies - delay) < 0) {
		del_timer(&fd_timer);
		fd_timer.function = function;
		fd_timer.expires = delay;
		add_timer(&fd_timer);
		return 1;
	}
	return 0;
}

static DEFINE_SPINLOCK(floppy_hlt_lock);
static int hlt_disabled;
static void floppy_disable_hlt(void)
{
	unsigned long flags;

	spin_lock_irqsave(&floppy_hlt_lock, flags);
	if (!hlt_disabled) {
		hlt_disabled = 1;
#ifdef HAVE_DISABLE_HLT
		disable_hlt();
#endif
	}
	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
}

static void floppy_enable_hlt(void)
{
	unsigned long flags;

	spin_lock_irqsave(&floppy_hlt_lock, flags);
	if (hlt_disabled) {
		hlt_disabled = 0;
#ifdef HAVE_DISABLE_HLT
		enable_hlt();
#endif
	}
	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
}

static void setup_DMA(void)
{
	unsigned long f;

#ifdef FLOPPY_SANITY_CHECK
	if (raw_cmd->length == 0) {
		int i;

		printk("zero dma transfer size:");
		for (i = 0; i < raw_cmd->cmd_count; i++)
			printk("%x,", raw_cmd->cmd[i]);
		printk("\n");
		cont->done(0);
		FDCS->reset = 1;
		return;
	}
	if (((unsigned long)raw_cmd->kernel_data) % 512) {
		printk("non aligned address: %p\n", raw_cmd->kernel_data);
		cont->done(0);
		FDCS->reset = 1;
		return;
	}
#endif
	f = claim_dma_lock();
	fd_disable_dma();
#ifdef fd_dma_setup
	if (fd_dma_setup(raw_cmd->kernel_data, raw_cmd->length,
			 (raw_cmd->flags & FD_RAW_READ) ?
			 DMA_MODE_READ : DMA_MODE_WRITE, FDCS->address) < 0) {
		release_dma_lock(f);
		cont->done(0);
		FDCS->reset = 1;
		return;
	}
	release_dma_lock(f);
#else
	fd_clear_dma_ff();
	fd_cacheflush(raw_cmd->kernel_data, raw_cmd->length);
	fd_set_dma_mode((raw_cmd->flags & FD_RAW_READ) ?
			DMA_MODE_READ : DMA_MODE_WRITE);
	fd_set_dma_addr(raw_cmd->kernel_data);
	fd_set_dma_count(raw_cmd->length);
	virtual_dma_port = FDCS->address;
	fd_enable_dma();
	release_dma_lock(f);
#endif
	floppy_disable_hlt();
}

static void show_floppy(void);

/* waits until the fdc becomes ready */
static int wait_til_ready(void)
{
	int counter, status;
	if (FDCS->reset)
		return -1;
	for (counter = 0; counter < 10000; counter++) {
		status = fd_inb(FD_STATUS);
		if (status & STATUS_READY)
			return status;
	}
	if (!initialising) {
		DPRINT("Getstatus times out (%x) on fdc %d\n", status, fdc);
		show_floppy();
	}
	FDCS->reset = 1;
	return -1;
}

/* sends a command byte to the fdc */
static int output_byte(char byte)
{
	int status;

	if ((status = wait_til_ready()) < 0)
		return -1;
	if ((status & (STATUS_READY | STATUS_DIR | STATUS_DMA)) == STATUS_READY) {
		fd_outb(byte, FD_DATA);
#ifdef FLOPPY_SANITY_CHECK
		output_log[output_log_pos].data = byte;
		output_log[output_log_pos].status = status;
		output_log[output_log_pos].jiffies = jiffies;
		output_log_pos = (output_log_pos + 1) % OLOGSIZE;
#endif
		return 0;
	}
	FDCS->reset = 1;
	if (!initialising) {
		DPRINT("Unable to send byte %x to FDC. Fdc=%x Status=%x\n",
		       byte, fdc, status);
		show_floppy();
	}
	return -1;
}

#define LAST_OUT(x) if (output_byte(x)<0){ reset_fdc();return;}

/* gets the response from the fdc */
static int result(void)
{
	int i, status = 0;

	for (i = 0; i < MAX_REPLIES; i++) {
		if ((status = wait_til_ready()) < 0)
			break;
		status &= STATUS_DIR | STATUS_READY | STATUS_BUSY | STATUS_DMA;
		if ((status & ~STATUS_BUSY) == STATUS_READY) {
#ifdef FLOPPY_SANITY_CHECK
			resultjiffies = jiffies;
			resultsize = i;
#endif
			return i;
		}
		if (status == (STATUS_DIR | STATUS_READY | STATUS_BUSY))
			reply_buffer[i] = fd_inb(FD_DATA);
		else
			break;
	}
	if (!initialising) {
		DPRINT
		    ("get result error. Fdc=%d Last status=%x Read bytes=%d\n",
		     fdc, status, i);
		show_floppy();
	}
	FDCS->reset = 1;
	return -1;
}

#define MORE_OUTPUT -2
/* does the fdc need more output? */
static int need_more_output(void)
{
	int status;
	if ((status = wait_til_ready()) < 0)
		return -1;
	if ((status & (STATUS_READY | STATUS_DIR | STATUS_DMA)) == STATUS_READY)
		return MORE_OUTPUT;
	return result();
}

/* Set perpendicular mode as required, based on data rate, if supported.
 * 82077 Now tested. 1Mbps data rate only possible with 82077-1.
 */
static inline void perpendicular_mode(void)
{
	unsigned char perp_mode;

	if (raw_cmd->rate & 0x40) {
		switch (raw_cmd->rate & 3) {
		case 0:
			perp_mode = 2;
			break;
		case 3:
			perp_mode = 3;
			break;
		default:
			DPRINT("Invalid data rate for perpendicular mode!\n");
			cont->done(0);
			FDCS->reset = 1;	/* convenient way to return to
						 * redo without to much hassle (deep
						 * stack et al. */
			return;
		}
	} else
		perp_mode = 0;

	if (FDCS->perp_mode == perp_mode)
		return;
	if (FDCS->version >= FDC_82077_ORIG) {
		output_byte(FD_PERPENDICULAR);
		output_byte(perp_mode);
		FDCS->perp_mode = perp_mode;
	} else if (perp_mode) {
		DPRINT("perpendicular mode not supported by this FDC.\n");
	}
}				/* perpendicular_mode */

static int fifo_depth = 0xa;
static int no_fifo;

static int fdc_configure(void)
{
	/* Turn on FIFO */
	output_byte(FD_CONFIGURE);
	if (need_more_output() != MORE_OUTPUT)
		return 0;
	output_byte(0);
	output_byte(0x10 | (no_fifo & 0x20) | (fifo_depth & 0xf));
	output_byte(0);		/* pre-compensation from track
				   0 upwards */
	return 1;
}

#define NOMINAL_DTR 500

/* Issue a "SPECIFY" command to set the step rate time, head unload time,
 * head load time, and DMA disable flag to values needed by floppy.
 *
 * The value "dtr" is the data transfer rate in Kbps.  It is needed
 * to account for the data rate-based scaling done by the 82072 and 82077
 * FDC types.  This parameter is ignored for other types of FDCs (i.e.
 * 8272a).
 *
 * Note that changing the data transfer rate has a (probably deleterious)
 * effect on the parameters subject to scaling for 82072/82077 FDCs, so
 * fdc_specify is called again after each data transfer rate
 * change.
 *
 * srt: 1000 to 16000 in microseconds
 * hut: 16 to 240 milliseconds
 * hlt: 2 to 254 milliseconds
 *
 * These values are rounded up to the next highest available delay time.
 */
static void fdc_specify(void)
{
	unsigned char spec1, spec2;
	unsigned long srt, hlt, hut;
	unsigned long dtr = NOMINAL_DTR;
	unsigned long scale_dtr = NOMINAL_DTR;
	int hlt_max_code = 0x7f;
	int hut_max_code = 0xf;

	if (FDCS->need_configure && FDCS->version >= FDC_82072A) {
		fdc_configure();
		FDCS->need_configure = 0;
		/*DPRINT("FIFO enabled\n"); */
	}

	switch (raw_cmd->rate & 0x03) {
	case 3:
		dtr = 1000;
		break;
	case 1:
		dtr = 300;
		if (FDCS->version >= FDC_82078) {
			/* chose the default rate table, not the one
			 * where 1 = 2 Mbps */
			output_byte(FD_DRIVESPEC);
			if (need_more_output() == MORE_OUTPUT) {
				output_byte(UNIT(current_drive));
				output_byte(0xc0);
			}
		}
		break;
	case 2:
		dtr = 250;
		break;
	}

	if (FDCS->version >= FDC_82072) {
		scale_dtr = dtr;
		hlt_max_code = 0x00;	/* 0==256msec*dtr0/dtr (not linear!) */
		hut_max_code = 0x0;	/* 0==256msec*dtr0/dtr (not linear!) */
	}

	/* Convert step rate from microseconds to milliseconds and 4 bits */
	srt = 16 - (DP->srt * scale_dtr / 1000 + NOMINAL_DTR - 1) / NOMINAL_DTR;
	if (slow_floppy) {
		srt = srt / 4;
	}
	SUPBOUND(srt, 0xf);
	INFBOUND(srt, 0);

	hlt = (DP->hlt * scale_dtr / 2 + NOMINAL_DTR - 1) / NOMINAL_DTR;
	if (hlt < 0x01)
		hlt = 0x01;
	else if (hlt > 0x7f)
		hlt = hlt_max_code;

	hut = (DP->hut * scale_dtr / 16 + NOMINAL_DTR - 1) / NOMINAL_DTR;
	if (hut < 0x1)
		hut = 0x1;
	else if (hut > 0xf)
		hut = hut_max_code;

	spec1 = (srt << 4) | hut;
	spec2 = (hlt << 1) | (use_virtual_dma & 1);

	/* If these parameters did not change, just return with success */
	if (FDCS->spec1 != spec1 || FDCS->spec2 != spec2) {
		/* Go ahead and set spec1 and spec2 */
		output_byte(FD_SPECIFY);
		output_byte(FDCS->spec1 = spec1);
		output_byte(FDCS->spec2 = spec2);
	}
}				/* fdc_specify */

/* Set the FDC's data transfer rate on behalf of the specified drive.
 * NOTE: with 82072/82077 FDCs, changing the data rate requires a reissue
 * of the specify command (i.e. using the fdc_specify function).
 */
static int fdc_dtr(void)
{
	/* If data rate not already set to desired value, set it. */
	if ((raw_cmd->rate & 3) == FDCS->dtr)
		return 0;

	/* Set dtr */
	fd_outb(raw_cmd->rate & 3, FD_DCR);

	/* TODO: some FDC/drive combinations (C&T 82C711 with TEAC 1.2MB)
	 * need a stabilization period of several milliseconds to be
	 * enforced after data rate changes before R/W operations.
	 * Pause 5 msec to avoid trouble. (Needs to be 2 jiffies)
	 */
	FDCS->dtr = raw_cmd->rate & 3;
	return (fd_wait_for_completion(jiffies + 2UL * HZ / 100,
				       (timeout_fn) floppy_ready));
}				/* fdc_dtr */

static void tell_sector(void)
{
	printk(": track %d, head %d, sector %d, size %d",
	       R_TRACK, R_HEAD, R_SECTOR, R_SIZECODE);
}				/* tell_sector */

/*
 * OK, this error interpreting routine is called after a
 * DMA read/write has succeeded
 * or failed, so we check the results, and copy any buffers.
 * hhb: Added better error reporting.
 * ak: Made this into a separate routine.
 */
static int interpret_errors(void)
{
	char bad;

	if (inr != 7) {
		DPRINT("-- FDC reply error");
		FDCS->reset = 1;
		return 1;
	}

	/* check IC to find cause of interrupt */
	switch (ST0 & ST0_INTR) {
	case 0x40:		/* error occurred during command execution */
		if (ST1 & ST1_EOC)
			return 0;	/* occurs with pseudo-DMA */
		bad = 1;
		if (ST1 & ST1_WP) {
			DPRINT("Drive is write protected\n");
			CLEARF(FD_DISK_WRITABLE);
			cont->done(0);
			bad = 2;
		} else if (ST1 & ST1_ND) {
			SETF(FD_NEED_TWADDLE);
		} else if (ST1 & ST1_OR) {
			if (DP->flags & FTD_MSG)
				DPRINT("Over/Underrun - retrying\n");
			bad = 0;
		} else if (*errors >= DP->max_errors.reporting) {
			DPRINT("");
			if (ST0 & ST0_ECE) {
				printk("Recalibrate failed!");
			} else if (ST2 & ST2_CRC) {
				printk("data CRC error");
				tell_sector();
			} else if (ST1 & ST1_CRC) {
				printk("CRC error");
				tell_sector();
			} else if ((ST1 & (ST1_MAM | ST1_ND))
				   || (ST2 & ST2_MAM)) {