historical/gems-kernel.git/source/THIRDPARTY/linux-old/drivers/block/floppy.c

/*
 *  linux/kernel/floppy.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * 02.12.91 - Changed to static variables to indicate need for reset
 * and recalibrate. This makes some things easier (output_byte reset
 * checking etc), and means less interrupt jumping in case of errors,
 * so the code is hopefully easier to understand.
 */

/*
 * This file is certainly a mess. I've tried my best to get it working,
 * but I don't like programming floppies, and I have only one anyway.
 * Urgel. I should check for more errors, and do more graceful error
 * recovery. Seems there are problems with several drives. I've tried to
 * correct them. No promises. 
 */

/*
 * As with hd.c, all routines within this file can (and will) be called
 * by interrupts, so extreme caution is needed. A hardware interrupt
 * handler may not sleep, or a kernel panic will happen. Thus I cannot
 * call "floppy-on" directly, but have to set a special timer interrupt
 * etc.
 */

/*
 * 28.02.92 - made track-buffering routines, based on the routines written
 * by entropy@wintermute.wpi.edu (Lawrence Foard). Linus.
 */

/*
 * Automatic floppy-detection and formatting written by Werner Almesberger
 * (almesber@nessie.cs.id.ethz.ch), who also corrected some problems with
 * the floppy-change signal detection.
 */

/*
 * 1992/7/22 -- Hennus Bergman: Added better error reporting, fixed 
 * FDC data overrun bug, added some preliminary stuff for vertical
 * recording support.
 *
 * 1992/9/17: Added DMA allocation & DMA functions. -- hhb.
 *
 * TODO: Errors are still not counted properly.
 */

/* 1992/9/20
 * Modifications for ``Sector Shifting'' by Rob Hooft (hooft@chem.ruu.nl)
 * modelled after the freeware MS/DOS program fdformat/88 V1.8 by 
 * Christoph H. Hochst\"atter.
 * I have fixed the shift values to the ones I always use. Maybe a new
 * ioctl() should be created to be able to modify them.
 * There is a bug in the driver that makes it impossible to format a
 * floppy as the first thing after bootup.
 */

/*
 * 1993/4/29 -- Linus -- cleaned up the timer handling in the kernel, and
 * this helped the floppy driver as well. Much cleaner, and still seems to
 * work.
 */

#define REALLY_SLOW_IO
#define FLOPPY_IRQ 6
#define FLOPPY_DMA 2

#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/fdreg.h>
#include <linux/fd.h>
#include <linux/errno.h>

#include <asm/dma.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/segment.h>

#define MAJOR_NR FLOPPY_MAJOR
#include "blk.h"

static unsigned int changed_floppies = 0, fake_change = 0;

static int initial_reset_flag = 0;
static int need_configure = 1;		/* for 82077 */
static int recalibrate = 0;
static int reset = 0;
static int recover = 0; /* recalibrate immediately after resetting */
static int seek = 0;

static unsigned char current_DOR = 0x0C;
static unsigned char running = 0;

#define TYPE(x) ((x)>>2)
#define DRIVE(x) ((x)&0x03)

/*
 * Note that MAX_ERRORS=X doesn't imply that we retry every bad read
 * max X times - some types of errors increase the errorcount by 2 or
 * even 3, so we might actually retry only X/2 times before giving up.
 */
#define MAX_ERRORS 12

/*
 * Maximum disk size (in kilobytes). This default is used whenever the
 * current disk size is unknown.
 */
#define MAX_DISK_SIZE 1440

/*
 * Maximum number of sectors in a track buffer. Track buffering is disabled
 * if tracks are bigger.
 */
#define MAX_BUFFER_SECTORS 18

/*
 * The DMA channel used by the floppy controller cannot access data at
 * addresses >= 16MB
 *
 * Went back to the 1MB limit, as some people had problems with the floppy
 * driver otherwise. It doesn't matter much for performance anyway, as most
 * floppy accesses go through the track buffer.
 */
#define LAST_DMA_ADDR	(0x100000 - BLOCK_SIZE)

/*
 * globals used by 'result()'
 */
#define MAX_REPLIES 7
static unsigned char reply_buffer[MAX_REPLIES];
#define ST0 (reply_buffer[0])
#define ST1 (reply_buffer[1])
#define ST2 (reply_buffer[2])
#define ST3 (reply_buffer[3])

/*
 * This struct defines the different floppy types.
 *
 * The 'stretch' tells if the tracks need to be doubled for some
 * types (ie 360kB diskette in 1.2MB drive etc). Others should
 * be self-explanatory.
 */
static struct floppy_struct floppy_type[] = {
	{    0, 0,0, 0,0,0x00,0x00,0x00,0x00,NULL },	/* no testing */
	{  720, 9,2,40,0,0x2A,0x02,0xDF,0x50,NULL },	/* 360kB PC diskettes */
	{ 2400,15,2,80,0,0x1B,0x00,0xDF,0x54,NULL },	/* 1.2 MB AT-diskettes */
	{  720, 9,2,40,1,0x2A,0x02,0xDF,0x50,NULL },	/* 360kB in 720kB drive */
	{ 1440, 9,2,80,0,0x2A,0x02,0xDF,0x50,NULL },	/* 3.5" 720kB diskette */
	{  720, 9,2,40,1,0x23,0x01,0xDF,0x50,NULL },	/* 360kB in 1.2MB drive */
	{ 1440, 9,2,80,0,0x23,0x01,0xDF,0x50,NULL },	/* 720kB in 1.2MB drive */
	{ 2880,18,2,80,0,0x1B,0x00,0xCF,0x6C,NULL },	/* 1.44MB diskette */
};

/*
 * Auto-detection. Each drive type has a pair of formats which are
 * used in succession to try to read the disk. If the FDC cannot lock onto
 * the disk, the next format is tried. This uses the variable 'probing'.
 */
static struct floppy_struct floppy_types[] = {
	{  720, 9,2,40,0,0x2A,0x02,0xDF,0x50,"360k/PC" }, /* 360kB PC diskettes */
	{  720, 9,2,40,0,0x2A,0x02,0xDF,0x50,"360k/PC" }, /* 360kB PC diskettes */
	{ 2400,15,2,80,0,0x1B,0x00,0xDF,0x54,"1.2M" },	  /* 1.2 MB AT-diskettes */
	{  720, 9,2,40,1,0x23,0x01,0xDF,0x50,"360k/AT" }, /* 360kB in 1.2MB drive */
	{ 1440, 9,2,80,0,0x2A,0x02,0xDF,0x50,"720k" },	  /* 3.5" 720kB diskette */
	{ 1440, 9,2,80,0,0x2A,0x02,0xDF,0x50,"720k" },	  /* 3.5" 720kB diskette */
	{ 2880,18,2,80,0,0x1B,0x00,0xCF,0x6C,"1.44M" },	  /* 1.44MB diskette */
	{ 1440, 9,2,80,0,0x2A,0x02,0xDF,0x50,"720k/AT" }, /* 3.5" 720kB diskette */
};

/* Auto-detection: Disk type used until the next media change occurs. */
struct floppy_struct *current_type[4] = { NULL, NULL, NULL, NULL };

/* This type is tried first. */
struct floppy_struct *base_type[4];

/*
 * User-provided type information. current_type points to
 * the respective entry of this array.
 */
struct floppy_struct user_params[4];

static int floppy_sizes[] ={
	MAX_DISK_SIZE, MAX_DISK_SIZE, MAX_DISK_SIZE, MAX_DISK_SIZE,
	 360, 360 ,360, 360,
	1200,1200,1200,1200,
	 360, 360, 360, 360,
	 720, 720, 720, 720,
	 360, 360, 360, 360,
	 720, 720, 720, 720,
	1440,1440,1440,1440
};

/*
 * The driver is trying to determine the correct media format
 * while probing is set. rw_interrupt() clears it after a
 * successful access.
 */
static int probing = 0;

/*
 * (User-provided) media information is _not_ discarded after a media change
 * if the corresponding keep_data flag is non-zero. Positive values are
 * decremented after each probe.
 */
static int keep_data[4] = { 0,0,0,0 };

/*
 * Announce successful media type detection and media information loss after
 * disk changes.
 * Also used to enable/disable printing of overrun warnings.
 */
static ftd_msg[4] = { 0,0,0,0 };

/* Prevent "aliased" accesses. */

static fd_ref[4] = { 0,0,0,0 };
static fd_device[4] = { 0,0,0,0 };

/* Synchronization of FDC access. */
static volatile int format_status = FORMAT_NONE, fdc_busy = 0;
static struct wait_queue *fdc_wait = NULL, *format_done = NULL;

/* Errors during formatting are counted here. */
static int format_errors;

/* Format request descriptor. */
static struct format_descr format_req;

/*
 * Current device number. Taken either from the block header or from the
 * format request descriptor.
 */
#define CURRENT_DEVICE (format_status == FORMAT_BUSY ? format_req.device : \
   (CURRENT->dev))

/* Current error count. */
#define CURRENT_ERRORS (format_status == FORMAT_BUSY ? format_errors : \
    (CURRENT->errors))

/*
 * Threshold for reporting FDC errors to the console.
 * Setting this to zero may flood your screen when using
 * ultra cheap floppies ;-)
 */
static unsigned short min_report_error_cnt[4] = {2, 2, 2, 2};

/*
 * Rate is 0 for 500kb/s, 1 for 300kbps, 2 for 250kbps
 * Spec1 is 0xSH, where S is stepping rate (F=1ms, E=2ms, D=3ms etc),
 * H is head unload time (1=16ms, 2=32ms, etc)
 *
 * Spec2 is (HLD<<1 | ND), where HLD is head load time (1=2ms, 2=4 ms etc)
 * and ND is set means no DMA. Hardcoded to 6 (HLD=6ms, use DMA).
 */

/*
 * Track buffer and block buffer (in case track buffering doesn't work).
 * Because these are written to by the DMA controller, they must
 * not contain a 64k byte boundary crossing, or data will be
 * corrupted/lost. Alignment of these is enforced in boot/head.s.
 * Note that you must not change the sizes below without updating head.s.
 */
extern char tmp_floppy_area[BLOCK_SIZE];
extern char floppy_track_buffer[512*2*MAX_BUFFER_SECTORS];

static void redo_fd_request(void);

/*
 * These are global variables, as that's the easiest way to give
 * information to interrupts. They are the data used for the current
 * request.
 */
#define NO_TRACK 255

static int read_track = 0;	/* flag to indicate if we want to read entire track */
static int buffer_track = -1;
static int buffer_drive = -1;
static int cur_spec1 = -1;
static int cur_rate = -1;
static struct floppy_struct * floppy = floppy_type;
static unsigned char current_drive = 255;
static unsigned char sector = 0;
static unsigned char head = 0;
static unsigned char track = 0;
static unsigned char seek_track = 0;
static unsigned char current_track = NO_TRACK;
static unsigned char command = 0;
static unsigned char fdc_version = FDC_TYPE_STD;	/* FDC version code */

static void floppy_ready(void);

static void select_callback(unsigned long unused)
{
	floppy_ready();
}

static void floppy_select(unsigned int nr)
{
	static struct timer_list select = { NULL, 0, 0, select_callback };

	if (current_drive == (current_DOR & 3)) {
		floppy_ready();
		return;
	}
	seek = 1;
	current_track = NO_TRACK;
	current_DOR &= 0xFC;
	current_DOR |= current_drive;
	outb(current_DOR,FD_DOR);
	del_timer(&select);
	select.expires = 2;
	add_timer(&select);
}

static void motor_on_callback(unsigned long nr)
{
	running |= 0x10 << nr;
	floppy_select(nr);
}

static struct timer_list motor_on_timer[4] = {
	{ NULL, 0, 0, motor_on_callback },
	{ NULL, 0, 1, motor_on_callback },
	{ NULL, 0, 2, motor_on_callback },
	{ NULL, 0, 3, motor_on_callback }
};

static void motor_off_callback(unsigned long nr)
{
	unsigned char mask = ~(0x10 << nr);
	cli();
	running &= mask;
	current_DOR &= mask;
	outb(current_DOR,FD_DOR);
	sti();
}

static struct timer_list motor_off_timer[4] = {
	{ NULL, 0, 0, motor_off_callback },
	{ NULL, 0, 1, motor_off_callback },
	{ NULL, 0, 2, motor_off_callback },
	{ NULL, 0, 3, motor_off_callback }
};

static void floppy_on(unsigned int nr)
{
	unsigned char mask = 0x10 << nr;

	del_timer(motor_off_timer + nr);
	if (mask & running)
		floppy_select(nr);
	if (!(mask & current_DOR)) {
		del_timer(motor_on_timer + nr);
		motor_on_timer[nr].expires = HZ;
		add_timer(motor_on_timer + nr);
	}
	current_DOR &= 0xFC;
	current_DOR |= mask;
	current_DOR |= nr;
	outb(current_DOR,FD_DOR);
}

static void floppy_off(unsigned int nr)
{
	del_timer(motor_off_timer+nr);
	motor_off_timer[nr].expires = 3*HZ;
	add_timer(motor_off_timer+nr);
}

void request_done(int uptodate)
{
	timer_active &= ~(1 << FLOPPY_TIMER);
	if (format_status != FORMAT_BUSY)
		end_request(uptodate);
	else {
		format_status = uptodate ? FORMAT_OKAY : FORMAT_ERROR;
		wake_up(&format_done);
	}
}

/*
 * floppy-change is never called from an interrupt, so we can relax a bit
 * here, sleep etc. Note that floppy-on tries to set current_DOR to point
 * to the desired drive, but it will probably not survive the sleep if
 * several floppies are used at the same time: thus the loop.
 */
int floppy_change(struct buffer_head * bh)
{
	unsigned int mask = 1 << (bh->b_dev & 0x03);

	if (MAJOR(bh->b_dev) != MAJOR_NR) {
		printk("floppy_changed: not a floppy\n");
		return 0;
	}
	if (fake_change & mask) {
		buffer_track = -1;
		fake_change &= ~mask;
/* omitting the next line breaks formatting in a horrible way ... */
		changed_floppies &= ~mask;
		return 1;
	}
	if (changed_floppies & mask) {
		buffer_track = -1;
		changed_floppies &= ~mask;
		recalibrate = 1;
		return 1;
	}
	if (!bh)
		return 0;
	if (bh->b_dirt)
		ll_rw_block(WRITE, 1, &bh);
	else {
		buffer_track = -1;
		bh->b_uptodate = 0;
		ll_rw_block(READ, 1, &bh);
	}
	wait_on_buffer(bh);
	if (changed_floppies & mask) {
		changed_floppies &= ~mask;
		recalibrate = 1;
		return 1;
	}
	return 0;
}

#define copy_buffer(from,to) \
__asm__("cld ; rep ; movsl" \
	: \
	:"c" (BLOCK_SIZE/4),"S" ((long)(from)),"D" ((long)(to)) \
	:"cx","di","si")

static void setup_DMA(void)
{
	unsigned long addr,count;
	unsigned char dma_code;

	dma_code = DMA_WRITE;
	if (command == FD_READ)
		dma_code = DMA_READ;
	if (command == FD_FORMAT) {
		addr = (long) tmp_floppy_area;
		count = floppy->sect*4;
	} else {
		addr = (long) CURRENT->buffer;
		count = 1024;
	}
	if (read_track) {
/* mark buffer-track bad, in case all this fails.. */
		buffer_drive = buffer_track = -1;
		count = floppy->sect*floppy->head*512;
		addr = (long) floppy_track_buffer;
	} else if (addr >= LAST_DMA_ADDR) {
		addr = (long) tmp_floppy_area;
		if (command == FD_WRITE)
			copy_buffer(CURRENT->buffer,tmp_floppy_area);
	}
	cli();
	disable_dma(FLOPPY_DMA);
	clear_dma_ff(FLOPPY_DMA);
	set_dma_mode(FLOPPY_DMA, (command == FD_READ)? DMA_MODE_READ : DMA_MODE_WRITE);
	set_dma_addr(FLOPPY_DMA, addr);
	set_dma_count(FLOPPY_DMA, count);
	enable_dma(FLOPPY_DMA);
	sti();
}

static void output_byte(char byte)
{
	int counter;
	unsigned char status;

	if (reset)
		return;
	for(counter = 0 ; counter < 10000 ; counter++) {
		status = inb_p(FD_STATUS) & (STATUS_READY | STATUS_DIR);
		if (status == STATUS_READY) {
			outb(byte,FD_DATA);
			return;
		}
	}
	current_track = NO_TRACK;
	reset = 1;
	printk("Unable to send byte to FDC\n");
}

static int result(void)
{
	int i = 0, counter, status;

	if (reset)
		return -1;
	for (counter = 0 ; counter < 10000 ; counter++) {
		status = inb_p(FD_STATUS)&(STATUS_DIR|STATUS_READY|STATUS_BUSY);
		if (status == STATUS_READY) {
			return i;
		}
		if (status == (STATUS_DIR|STATUS_READY|STATUS_BUSY)) {
			if (i >= MAX_REPLIES) {
				printk("floppy_stat reply overrun\n");
				break;
			}
			reply_buffer[i++] = inb_p(FD_DATA);
		}
	}
	reset = 1;
	current_track = NO_TRACK;
	printk("Getstatus times out\n");
	return -1;
}

static void bad_flp_intr(void)
{
	int errors;

	current_track = NO_TRACK;
	if (format_status == FORMAT_BUSY)
		errors = ++format_errors;
	else if (!CURRENT) {
		printk(DEVICE_NAME ": no current request\n");
		reset = recalibrate = 1;
		return;
	} else
		errors = ++CURRENT->errors;
	if (errors > MAX_ERRORS) {
		request_done(0);
	}
	if (errors > MAX_ERRORS/2)
		reset = 1;
	else
		recalibrate = 1;
}	


/* Set perpendicular mode as required, based on data rate, if supported.
 * 82077 Untested! 1Mbps data rate only possible with 82077-1.
 * TODO: increase MAX_BUFFER_SECTORS, add floppy_type entries.
 */
static inline void perpendicular_mode(unsigned char rate)
{
	if (fdc_version == FDC_TYPE_82077) {
		output_byte(FD_PERPENDICULAR);
		if (rate & 0x40) {
			unsigned char r = rate & 0x03;
			if (r == 0)
				output_byte(2);	/* perpendicular, 500 kbps */
			else if (r == 3)
				output_byte(3);	/* perpendicular, 1Mbps */
			else {
				printk(DEVICE_NAME ": Invalid data rate for perpendicular mode!\n");
				reset = 1;
			}
		} else
			output_byte(0);		/* conventional mode */
	} else {
		if (rate & 0x40) {
			printk(DEVICE_NAME ": perpendicular mode not supported by this FDC.\n");
			reset = 1;
		}
	}
} /* perpendicular_mode */


/*
 * This has only been tested for the case fdc_version == FDC_TYPE_STD.
 * In case you have a 82077 and want to test it, you'll have to compile
 * with `FDC_FIFO_UNTESTED' defined. You may also want to add support for
 * recognizing drives with vertical recording support.
 */
static void configure_fdc_mode(void)
{
	if (need_configure && (fdc_version == FDC_TYPE_82077)) {
		/* Enhanced version with FIFO & vertical recording. */
		output_byte(FD_CONFIGURE);
		output_byte(0);
		output_byte(0x1A);	/* FIFO on, polling off, 10 byte threshold */
		output_byte(0);		/* precompensation from track 0 upwards */
		need_configure = 0;
		printk(DEVICE_NAME ": FIFO enabled\n");
	}
	if (cur_spec1 != floppy->spec1) {
		cur_spec1 = floppy->spec1;
		output_byte(FD_SPECIFY);
		output_byte(cur_spec1);		/* hut etc */
		output_byte(6);			/* Head load time =6ms, DMA */
	}
	if (cur_rate != floppy->rate) {
		/* use bit 6 of floppy->rate to indicate perpendicular mode */
		perpendicular_mode(floppy->rate);
		outb_p((cur_rate = (floppy->rate)) & ~0x40, FD_DCR);
	}
} /* configure_fdc_mode */


static void tell_sector(int nr)
{
	if (nr!=7) {
		printk(" -- FDC reply errror");
		reset = 1;
	} else
		printk(": track %d, head %d, sector %d", reply_buffer[3],
			reply_buffer[4], reply_buffer[5]);
} /* tell_sector */


/*
 * Ok, this interrupt 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.
 */
static void rw_interrupt(void)
{
	char * buffer_area;
	int nr;
	char bad;

	nr = result();
	/* check IC to find cause of interrupt */
	switch ((ST0 & ST0_INTR)>>6) {
		case 1:	/* error occured during command execution */
			bad = 1;
			if (ST1 & ST1_WP) {
				printk(DEVICE_NAME ": Drive %d is write protected\n", current_drive);
				request_done(0);
				bad = 0;
			} else if (ST1 & ST1_OR) {
				if (ftd_msg[ST0 & ST0_DS])
					printk(DEVICE_NAME ": Over/Underrun - retrying\n");
				/* could continue from where we stopped, but ... */
				bad = 0;
			} else if (CURRENT_ERRORS > min_report_error_cnt[ST0 & ST0_DS]) {
				printk(DEVICE_NAME " %d: ", ST0 & ST0_DS);
				if (ST0 & ST0_ECE) {
					printk("Recalibrate failed!");
				} else if (ST2 & ST2_CRC) {
					printk("data CRC error");
					tell_sector(nr);
				} else if (ST1 & ST1_CRC) {
					printk("CRC error");
					tell_sector(nr);
				} else if ((ST1 & (ST1_MAM|ST1_ND)) || (ST2 & ST2_MAM)) {
					if (!probing) {
						printk("sector not found");
						tell_sector(nr);
					} else
						printk("probe failed...");
				} else if (ST2 & ST2_WC) {	/* seek error */
					printk("wrong cylinder");
				} else if (ST2 & ST2_BC) {	/* cylinder marked as bad */
					printk("bad cylinder");
				} else {
					printk("unknown error. ST[0..3] are: 0x%x 0x%x 0x%x 0x%x\n", ST0, ST1, ST2, ST3);
				}
				printk("\n");

			}
			if (bad)
				bad_flp_intr();
			redo_fd_request();
			return;
		case 2: /* invalid command given */
			printk(DEVICE_NAME ": Invalid FDC command given!\n");
			request_done(0);
			return;
		case 3:
			printk(DEVICE_NAME ": Abnormal termination caused by polling\n");
			bad_flp_intr();
			redo_fd_request();
			return;
		default: /* (0) Normal command termination */
			break;
	}

	if (probing) {
		int drive = MINOR(CURRENT->dev);

		if (ftd_msg[drive])
			printk("Auto-detected floppy type %s in fd%d\n",
			    floppy->name,drive);
		current_type[drive] = floppy;
		floppy_sizes[drive] = floppy->size >> 1;
		probing = 0;
	}
	if (read_track) {
		buffer_track = seek_track;
		buffer_drive = current_drive;
		buffer_area = floppy_track_buffer +
			((sector-1 + head*floppy->sect)<<9);
		copy_buffer(buffer_area,CURRENT->buffer);
	} else if (command == FD_READ &&
		(unsigned long)(CURRENT->buffer) >= LAST_DMA_ADDR)
		copy_buffer(tmp_floppy_area,CURRENT->buffer);
	request_done(1);
	redo_fd_request();
}

/*
 * We try to read tracks, but if we get too many errors, we
 * go back to reading just one sector at a time.
 *
 * This means we should be able to read a sector even if there
 * are other bad sectors on this track.
 */
inline void setup_rw_floppy(void)
{
	setup_DMA();
	do_floppy = rw_interrupt;
	output_byte(command);
	if (command != FD_FORMAT) {
		if (read_track) {
			output_byte(current_drive);
			output_byte(track);
			output_byte(0);
			output_byte(1);
		} else {
			output_byte(head<<2 | current_drive);
			output_byte(track);
			output_byte(head);
			output_byte(sector);
		}
		output_byte(2);		/* sector size = 512 */
		output_byte(floppy->sect);
		output_byte(floppy->gap);
		output_byte(0xFF);	/* sector size (0xff when n!=0 ?) */
	} else {
		output_byte(head<<2 | current_drive);
		output_byte(2);
		output_byte(floppy->sect);
		output_byte(floppy->fmt_gap);
		output_byte(FD_FILL_BYTE);
	}
	if (reset)
		redo_fd_request();
}

/*
 * This is the routine called after every seek (or recalibrate) interrupt
 * from the floppy controller. Note that the "unexpected interrupt" routine
 * also does a recalibrate, but doesn't come here.
 */
static void seek_interrupt(void)
{
/* sense drive status */
	output_byte(FD_SENSEI);
	if (result() != 2 || (ST0 & 0xF8) != 0x20 || ST1 != seek_track) {
		printk(DEVICE_NAME ": seek failed\n");
		recalibrate = 1;
		bad_flp_intr();
		redo_fd_request();
		return;
	}
	current_track = ST1;
	setup_rw_floppy();
}


/*
 * This routine is called when everything should be correctly set up
 * for the transfer (ie floppy motor is on and the correct floppy is
 * selected).
 */
static void transfer(void)
{
	read_track = (command == FD_READ) && (CURRENT_ERRORS < 4) &&
	    (floppy->sect <= MAX_BUFFER_SECTORS);

	configure_fdc_mode();

	if (reset) {
		redo_fd_request();
		return;
	}
	if (!seek) {
		setup_rw_floppy();
		return;
	}

	do_floppy = seek_interrupt;
	output_byte(FD_SEEK);
	if (read_track)
		output_byte(current_drive);
	else
		output_byte((head<<2) | current_drive);
	output_byte(seek_track);
	if (reset)
		redo_fd_request();
}

/*
 * Special case - used after a unexpected interrupt (or reset)
 */

static void recalibrate_floppy(void);

static void recal_interrupt(void)
{
	output_byte(FD_SENSEI);
	current_track = NO_TRACK;
	if (result()!=2 || (ST0 & 0xE0) == 0x60)
		reset = 1;
/* Recalibrate until track 0 is reached. Might help on some errors. */
	if ((ST0 & 0x10) == 0x10)
		recalibrate_floppy();	/* FIXME: should limit nr of recalibrates */
	else
		redo_fd_request();
}

static void unexpected_floppy_interrupt(void)
{
	current_track = NO_TRACK;
	output_byte(FD_SENSEI);
	printk(DEVICE_NAME ": unexpected interrupt\n");
	if (result()!=2 || (ST0 & 0xE0) == 0x60)
		reset = 1;
	else
		recalibrate = 1;
}

static void recalibrate_floppy(void)
{
	recalibrate = 0;
	current_track = 0;
	do_floppy = recal_interrupt;
	output_byte(FD_RECALIBRATE);
	output_byte(head<<2 | current_drive);
	if (reset)
		redo_fd_request();
}

/*
 * Must do 4 FD_SENSEIs after reset because of ``drive polling''.
 */
static void reset_interrupt(void)
{
	short i;

	for (i=0; i<4; i++) {
		output_byte(FD_SENSEI);
		(void) result();
	}
	output_byte(FD_SPECIFY);
	output_byte(cur_spec1);		/* hut etc */
	output_byte(6);			/* Head load time =6ms, DMA */
	configure_fdc_mode();		/* reprogram fdc */
	if (initial_reset_flag) {
		initial_reset_flag = 0;
		recalibrate = 1;
		reset = 0;
		return;
	}
	if (!recover)
		redo_fd_request();
	else {
		recalibrate_floppy();
		recover = 0;
	}
}

/*
 * reset is done by pulling bit 2 of DOR low for a while.
 */
static void reset_floppy(void)
{
	int i;

	do_floppy = reset_interrupt;
	reset = 0;
	current_track = NO_TRACK;
	cur_spec1 = -1;
	cur_rate = -1;
	recalibrate = 1;
	need_configure = 1;
	if (!initial_reset_flag)
		printk("Reset-floppy called\n");
	cli();
	outb_p(current_DOR & ~0x04, FD_DOR);
	for (i=0 ; i<1000 ; i++)
		__asm__("nop");
	outb(current_DOR, FD_DOR);
	sti();
}

static void floppy_shutdown(void)
{
	cli();
	do_floppy = NULL;
	request_done(0);
	recover = 1;
	reset_floppy();
	sti();
	redo_fd_request();
}

static void shake_done(void)
{
	current_track = NO_TRACK;
	if (inb(FD_DIR) & 0x80)
		request_done(0);
	redo_fd_request();
}

static int retry_recal(void (*proc)(void))
{
	output_byte(FD_SENSEI);
	if (result() == 2 && (ST0 & 0x10) != 0x10) return 0;
	do_floppy = proc;
	output_byte(FD_RECALIBRATE);
	output_byte(head<<2 | current_drive);
	return 1;
}

static void shake_zero(void)
{
	if (!retry_recal(shake_zero)) shake_done();
}

static void shake_one(void)
{
	if (retry_recal(shake_one)) return;
	do_floppy = shake_done;
	output_byte(FD_SEEK);
	output_byte(head << 2 | current_drive);
	output_byte(1);
}

static void floppy_ready(void)
{
	if (inb(FD_DIR) & 0x80) {
		changed_floppies |= 1<<current_drive;
		buffer_track = -1;
		if (keep_data[current_drive]) {
			if (keep_data[current_drive] > 0)
				keep_data[current_drive]--;
		} else {
			if (ftd_msg[current_drive] && current_type[current_drive] != NULL)
				printk("Disk type is undefined after disk "
				    "change in fd%d\n",current_drive);
			current_type[current_drive] = NULL;
			floppy_sizes[current_drive] = MAX_DISK_SIZE;
		}
/* Forcing the drive to seek makes the "media changed" condition go away.
 * There should be a cleaner solution for that ...
 */
		if (!reset && !recalibrate) {
			if (current_track && current_track != NO_TRACK)
				do_floppy = shake_zero;
			else
				do_floppy = shake_one;
			output_byte(FD_RECALIBRATE);
			output_byte(head<<2 | current_drive);
			return;
		}
	}
	if (reset) {
		reset_floppy();
		return;
	}
	if (recalibrate) {
		recalibrate_floppy();
		return;
	}
	transfer();
}

static void setup_format_params(void)
{
    unsigned char *here = (unsigned char *) tmp_floppy_area;
    int count,head_shift,track_shift,total_shift;

    /* allow for about 30ms for data transport per track */
    head_shift  = floppy->sect / 6;
    /* a ``cylinder'' is two tracks plus a little stepping time */
    track_shift = 2 * head_shift + 1; 
    /* count backwards */
    total_shift = floppy->sect - 
	((track_shift * track + head_shift * head) % floppy->sect);

    /* XXX: should do a check to see this fits in tmp_floppy_area!! */
    for (count = 0; count < floppy->sect; count++) {
	*here++ = track;
	*here++ = head;
	*here++ = 1 + (( count + total_shift ) % floppy->sect);
	*here++ = 2; /* 512 bytes */
    }
}

static void redo_fd_request(void)
{
	unsigned int block;
	char * buffer_area;
	int device;

	if (CURRENT && CURRENT->dev < 0) return;

repeat:
	if (format_status == FORMAT_WAIT)
		format_status = FORMAT_BUSY;
	if (format_status != FORMAT_BUSY) {
		if (!CURRENT) {
			if (!fdc_busy)
				printk("FDC access conflict!");
			fdc_busy = 0;
			wake_up(&fdc_wait);
			CLEAR_INTR;
			return;
		}
		if (MAJOR(CURRENT->dev) != MAJOR_NR)
			panic(DEVICE_NAME ": request list destroyed"); \
		if (CURRENT->bh) {
			if (!CURRENT->bh->b_lock)
				panic(DEVICE_NAME ": block not locked");
		}
	}
	seek = 0;
	probing = 0;
	device = MINOR(CURRENT_DEVICE);
	if (device > 3)
		floppy = (device >> 2) + floppy_type;
	else { /* Auto-detection */
		floppy = current_type[device & 3];
		if (!floppy) {
			probing = 1;
			floppy = base_type[device & 3];
			if (!floppy) {
				request_done(0);
				goto repeat;
			}
			if (CURRENT_ERRORS & 1)
				floppy++;
		}
	}
	if (format_status != FORMAT_BUSY) {
		if (current_drive != CURRENT_DEV) {
			current_track = NO_TRACK;
			current_drive = CURRENT_DEV;
		}
		block = CURRENT->sector;
		if (block+2 > floppy->size) {
			request_done(0);
			goto repeat;
		}
		sector = block % floppy->sect;
		block /= floppy->sect;
		head = block % floppy->head;
		track = block / floppy->head;
		seek_track = track << floppy->stretch;
		if (CURRENT->cmd == READ)
			command = FD_READ;
		else if (CURRENT->cmd == WRITE)
			command = FD_WRITE;
		else {
			printk("do_fd_request: unknown command\n");
			request_done(0);
			goto repeat;
		}
	} else {
		if (current_drive != (format_req.device & 3))
			current_track = NO_TRACK;
		current_drive = format_req.device & 3;
		if (((unsigned) format_req.track) >= floppy->track ||
		    (format_req.head & 0xfffe) || probing) {
			request_done(0);
			goto repeat;
		}
		head = format_req.head;
		track = format_req.track;
		seek_track = track << floppy->stretch;
		if (seek_track == buffer_track) buffer_track = -1;
		command = FD_FORMAT;
		setup_format_params();
	}
	timer_table[FLOPPY_TIMER].expires = jiffies+10*HZ;
	timer_active |= 1 << FLOPPY_TIMER;
	if ((seek_track == buffer_track) &&
	 (current_drive == buffer_drive)) {
		buffer_area = floppy_track_buffer +
			((sector + head*floppy->sect)<<9);
		if (command == FD_READ) {
			copy_buffer(buffer_area,CURRENT->buffer);
			request_done(1);
			goto repeat;
		} else if (command == FD_WRITE)
			copy_buffer(CURRENT->buffer,buffer_area);
	}
	if (seek_track != current_track)
		seek = 1;
	sector++;
	del_timer(motor_off_timer + current_drive);
	floppy_on(current_drive);
}

void do_fd_request(void)
{
	cli();
	while (fdc_busy) sleep_on(&fdc_wait);
	fdc_busy = 1;
	sti();
	redo_fd_request();
}

static int fd_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
    unsigned long param)
{
	int i,drive,cnt,okay;
	struct floppy_struct *this_floppy;

	switch (cmd) {
		RO_IOCTLS(inode->i_rdev,param);
	}
	drive = MINOR(inode->i_rdev);
	switch (cmd) {
		case FDFMTBEG:
			if (!suser())
				return -EPERM;
			return 0;
		case FDFMTEND:
			if (!suser())
				return -EPERM;
			cli();
			fake_change |= 1 << (drive & 3);
			sti();
			drive &= 3;
			cmd = FDCLRPRM;
			break;
		case FDGETPRM:
			if (drive > 3) this_floppy = &floppy_type[drive >> 2];
			else if ((this_floppy = current_type[drive & 3]) == NULL)
				    return -ENODEV;
			i = verify_area(VERIFY_WRITE,(void *) param,sizeof(struct floppy_struct));
			if (i)
				return i;
			for (cnt = 0; cnt < sizeof(struct floppy_struct); cnt++)
				put_fs_byte(((char *) this_floppy)[cnt],
				    (char *) param+cnt);
			return 0;
		case FDFMTTRK:
			if (!suser())
				return -EPERM;
			if (fd_ref[drive & 3] != 1)
				return -EBUSY;
			cli();
			while (format_status != FORMAT_NONE)
				sleep_on(&format_done);
			for (cnt = 0; cnt < sizeof(struct format_descr); cnt++)
				((char *) &format_req)[cnt] = get_fs_byte(
				    (char *) param+cnt);
			format_req.device = drive;
			format_status = FORMAT_WAIT;
			format_errors = 0;
			while (format_status != FORMAT_OKAY && format_status !=
			    FORMAT_ERROR) {
				if (fdc_busy) sleep_on(&fdc_wait);
				else {
					fdc_busy = 1;
					redo_fd_request();
				}
			}
			while (format_status != FORMAT_OKAY && format_status !=
			    FORMAT_ERROR)
				sleep_on(&format_done);
			sti();
			okay = format_status == FORMAT_OKAY;
			format_status = FORMAT_NONE;
			floppy_off(drive & 3);
			wake_up(&format_done);
			return okay ? 0 : -EIO;
		case FDFLUSH:
			if (!permission(inode, 2))
				return -EPERM;
			cli();
			fake_change |= 1 << (drive & 3);
			sti();
			check_disk_change(inode->i_rdev);
			return 0;
 	}
	if (!suser())
		return -EPERM;
	if (drive < 0 || drive > 3)
		return -EINVAL;
	switch (cmd) {
		case FDCLRPRM:
			current_type[drive] = NULL;
			floppy_sizes[drive] = MAX_DISK_SIZE;
			keep_data[drive] = 0;
			break;
		case FDSETPRM:
		case FDDEFPRM:
			memcpy_fromfs(user_params+drive,
				(void *) param,
				sizeof(struct floppy_struct));
			current_type[drive] = &user_params[drive];
			floppy_sizes[drive] = user_params[drive].size >> 1;
			if (cmd == FDDEFPRM)
				keep_data[drive] = -1;
			else {
				cli();
				while (fdc_busy) sleep_on(&fdc_wait);
				fdc_busy = 1;
				sti();
				outb_p((current_DOR & 0xfc) | drive |
				    (0x10 << drive),FD_DOR);
				for (cnt = 0; cnt < 1000; cnt++) __asm__("nop");
				if (inb(FD_DIR) & 0x80)
					keep_data[drive] = 1;
				else
					keep_data[drive] = 0;
				outb_p(current_DOR,FD_DOR);
				fdc_busy = 0;
				wake_up(&fdc_wait);
			}
			break;
		case FDMSGON:
			ftd_msg[drive] = 1;
			break;
		case FDMSGOFF:
			ftd_msg[drive] = 0;
			break;
		case FDSETEMSGTRESH:
			min_report_error_cnt[drive] = (unsigned short) (param & 0x0f);
			break;
		default:
			return -EINVAL;
	}
	return 0;
}

#define CMOS_READ(addr) ({ \
outb_p(addr,0x70); \
inb_p(0x71); \
})

static struct floppy_struct *find_base(int drive,int code)
{
	struct floppy_struct *base;

	if (code > 0 && code < 5) {
		base = &floppy_types[(code-1)*2];
		printk("fd%d is %s",drive,base->name);
		return base;
	}
	printk("fd%d is unknown type %d",drive,code);
	return NULL;
}

static void config_types(void)
{
	printk("Floppy drive(s): ");
	base_type[0] = find_base(0,(CMOS_READ(0x10) >> 4) & 15);
	if (((CMOS_READ(0x14) >> 6) & 1) == 0)
		base_type[1] = NULL;
	else {
		printk(", ");
		base_type[1] = find_base(1,CMOS_READ(0x10) & 15);
	}
	base_type[2] = base_type[3] = NULL;
	printk("\n");
}

/*
 * floppy_open check for aliasing (/dev/fd0 can be the same as
 * /dev/PS0 etc), and disallows simultaneous access to the same
 * drive with different device numbers.
 */
static int floppy_open(struct inode * inode, struct file * filp)
{
	int drive;
	int old_dev;

	drive = inode->i_rdev & 3;
	old_dev = fd_device[drive];
	if (fd_ref[drive])
		if (old_dev != inode->i_rdev)
			return -EBUSY;
	fd_ref[drive]++;
	fd_device[drive] = inode->i_rdev;
	buffer_drive = buffer_track = -1;
	if (old_dev && old_dev != inode->i_rdev)
		invalidate_buffers(old_dev);
	if (filp && filp->f_mode)
		check_disk_change(inode->i_rdev);
	return 0;
}

static void floppy_release(struct inode * inode, struct file * filp)
{
	sync_dev(inode->i_rdev);
	if (!fd_ref[inode->i_rdev & 3]--) {
		printk("floppy_release with fd_ref == 0");
		fd_ref[inode->i_rdev & 3] = 0;
	}
}

static struct file_operations floppy_fops = {
	NULL,			/* lseek - default */
	block_read,		/* read - general block-dev read */
	block_write,		/* write - general block-dev write */
	NULL,			/* readdir - bad */
	NULL,			/* select */
	fd_ioctl,		/* ioctl */
	NULL,			/* mmap */
	floppy_open,		/* open */
	floppy_release,		/* release */
	block_fsync		/* fsync */
};


/*
 * The version command is not supposed to generate an interrupt, but
 * my FDC does, except when booting in SVGA screen mode.
 * When it does generate an interrupt, it doesn't return any status bytes.
 * It appears to have something to do with the version command...
 *
 * This should never be called, because of the reset after the version check.
 */
static void ignore_interrupt(void)
{
	printk(DEVICE_NAME ": weird interrupt ignored (%d)\n", result());
	reset = 1;
	CLEAR_INTR;	/* ignore only once */
}


static void floppy_interrupt(int unused)
{
	void (*handler)(void) = DEVICE_INTR;

	DEVICE_INTR = NULL;
	if (!handler)
		handler = unexpected_floppy_interrupt;
	handler();
}

/*
 * This is the floppy IRQ description. The SA_INTERRUPT in sa_flags
 * means we run the IRQ-handler with interrupts disabled.
 */
static struct sigaction floppy_sigaction = {
	floppy_interrupt,
	0,
	SA_INTERRUPT,
	NULL
};

void floppy_init(void)
{
	outb(current_DOR,FD_DOR);
	if (register_blkdev(MAJOR_NR,"fd",&floppy_fops)) {
		printk("Unable to get major %d for floppy\n",MAJOR_NR);
		return;
	}
	blk_size[MAJOR_NR] = floppy_sizes;
	blk_dev[MAJOR_NR].request_fn = DEVICE_REQUEST;
	timer_table[FLOPPY_TIMER].fn = floppy_shutdown;
	timer_active &= ~(1 << FLOPPY_TIMER);
	config_types();
	if (irqaction(FLOPPY_IRQ,&floppy_sigaction))
		printk("Unable to grab IRQ%d for the floppy driver\n", FLOPPY_IRQ);
	if (request_dma(FLOPPY_DMA))
		printk("Unable to grab DMA%d for the floppy driver\n", FLOPPY_DMA);
	/* Try to determine the floppy controller type */
	DEVICE_INTR = ignore_interrupt;	/* don't ask ... */
	output_byte(FD_VERSION);	/* get FDC version code */
	if (result() != 1) {
		printk(DEVICE_NAME ": FDC failed to return version byte\n");
		fdc_version = FDC_TYPE_STD;
	} else
		fdc_version = reply_buffer[0];
	if (fdc_version != FDC_TYPE_STD) 
		printk(DEVICE_NAME ": FDC version 0x%x\n", fdc_version);
#ifndef FDC_FIFO_UNTESTED
	fdc_version = FDC_TYPE_STD;	/* force std fdc type; can't test other. */
#endif

	/* Not all FDCs seem to be able to handle the version command
	 * properly, so force a reset for the standard FDC clones,
	 * to avoid interrupt garbage.
	 */

	if (fdc_version == FDC_TYPE_STD) {
		initial_reset_flag = 1;
		reset_floppy();
	}
}