/*
   *  linux/amiga/amiflop.c
   *
   *  Copyright (C) 1993  Greg Harp
   *  Portions of this driver are based on code contributed by Brad Pepers
   *  
   *  revised 28.5.95 by Joerg Dorchain
   *  - now no bugs(?) any more for both HD & DD
   *  - added support for 40 Track 5.25" drives, 80-track hopefully behaves
   *    like 3.5" dd (no way to test - are there any 5.25" drives out there
   *    that work on an A4000?)
   *  - wrote formatting routine (maybe dirty, but works)
   *
   *  june/july 1995 added ms-dos support by Joerg Dorchain
   *  (portions based on messydos.device and various contributors)
   *  - currently only 9 and 18 sector disks
   *
   *  - fixed a bug with the internal trackbuffer when using multiple 
   *    disks the same time
   *  - made formatting a bit safer
   *  - added command line and machine based default for "silent" df0
   *
   *  december 1995 adapted for 1.2.13pl4 by Joerg Dorchain
   *  - works but I think it's inefficient. (look in redo_fd_request)
   *    But the changes were very efficient. (only three and a half lines)
   *
   *  january 1996 added special ioctl for tracking down read/write problems
   *  - usage ioctl(d, RAW_TRACK, ptr); the raw track buffer (MFM-encoded data
   *    is copied to area. (area should be large enough since no checking is
   *    done - 30K is currently sufficient). return the actual size of the
   *    trackbuffer
   *  - replaced udelays() by a timer (CIAA timer B) for the waits 
   *    needed for the disk mechanic.
   *
   *  february 1996 fixed error recovery and multiple disk access
   *  - both got broken the first time I tampered with the driver :-(
   *  - still not safe, but better than before
   *
   *  revised Marts 3rd, 1996 by Jes Sorensen for use in the 1.3.28 kernel.
   *  - Minor changes to accept the kdev_t.
   *  - Replaced some more udelays with ms_delays. Udelay is just a loop,
   *    and so the delay will be different depending on the given
   *    processor :-(
   *  - The driver could use a major cleanup because of the new
   *    major/minor handling that came with kdev_t. It seems to work for
   *    the time being, but I can't guarantee that it will stay like
   *    that when we start using 16 (24?) bit minors.
   *
   * restructured jan 1997 by Joerg Dorchain
   * - Fixed Bug accessing multiple disks
   * - some code cleanup
   * - added trackbuffer for each drive to speed things up
   * - fixed some race conditions (who finds the next may send it to me ;-)
   */
  
  #include <linux/module.h>

  #include <linux/slab.h>

  
  #include <linux/fd.h>
  #include <linux/hdreg.h>
  #include <linux/delay.h>
  #include <linux/init.h>

  #include <linux/mutex.h>

  #include <linux/amifdreg.h>
  #include <linux/amifd.h>

  #include <linux/fs.h>

  #include <linux/blkdev.h>
  #include <linux/elevator.h>

  #include <linux/interrupt.h>

  #include <linux/platform_device.h>

  
  #include <asm/setup.h>
  #include <asm/uaccess.h>
  #include <asm/amigahw.h>
  #include <asm/amigaints.h>
  #include <asm/irq.h>
  
  #undef DEBUG /* print _LOTS_ of infos */
  
  #define RAW_IOCTL
  #ifdef RAW_IOCTL
  #define IOCTL_RAW_TRACK 0x5254524B  /* 'RTRK' */
  #endif
  
  /*
   *  Defines
   */
  
  /*
   *  Error codes
   */
  #define FD_OK		0	/* operation succeeded */
  #define FD_ERROR	-1	/* general error (seek, read, write, etc) */
  #define FD_NOUNIT	1	/* unit does not exist */
  #define FD_UNITBUSY	2	/* unit already active */
  #define FD_NOTACTIVE	3	/* unit is not active */
  #define FD_NOTREADY	4	/* unit is not ready (motor not on/no disk) */
  
  #define MFM_NOSYNC	1
  #define MFM_HEADER	2
  #define MFM_DATA	3
  #define MFM_TRACK	4
  
  /*
   *  Floppy ID values
   */
  #define FD_NODRIVE	0x00000000  /* response when no unit is present */
  #define FD_DD_3 	0xffffffff  /* double-density 3.5" (880K) drive */
  #define FD_HD_3 	0x55555555  /* high-density 3.5" (1760K) drive */
  #define FD_DD_5 	0xaaaaaaaa  /* double-density 5.25" (440K) drive */

  static DEFINE_MUTEX(amiflop_mutex);

  static unsigned long int fd_def_df0 = FD_DD_3;     /* default for df0 if it doesn't identify */
  
  module_param(fd_def_df0, ulong, 0);
  MODULE_LICENSE("GPL");

  /*
   *  Macros
   */
  #define MOTOR_ON	(ciab.prb &= ~DSKMOTOR)
  #define MOTOR_OFF	(ciab.prb |= DSKMOTOR)
  #define SELECT(mask)    (ciab.prb &= ~mask)
  #define DESELECT(mask)  (ciab.prb |= mask)
  #define SELMASK(drive)  (1 << (3 + (drive & 3)))
  
  static struct fd_drive_type drive_types[] = {
  /*  code	name	   tr he   rdsz   wrsz sm pc1 pc2 sd  st st*/
  /*  warning: times are now in milliseconds (ms)                    */
  { FD_DD_3,	"DD 3.5",  80, 2, 14716, 13630, 1, 80,161, 3, 18, 1},
  { FD_HD_3,	"HD 3.5",  80, 2, 28344, 27258, 2, 80,161, 3, 18, 1},
  { FD_DD_5,	"DD 5.25", 40, 2, 14716, 13630, 1, 40, 81, 6, 30, 2},
  { FD_NODRIVE, "No Drive", 0, 0,     0,     0, 0,  0,  0,  0,  0, 0}
  };

  static int num_dr_types = ARRAY_SIZE(drive_types);

  
  static int amiga_read(int), dos_read(int);
  static void amiga_write(int), dos_write(int);
  static struct fd_data_type data_types[] = {
  	{ "Amiga", 11 , amiga_read, amiga_write},
  	{ "MS-Dos", 9, dos_read, dos_write}
  };
  
  /* current info on each unit */
  static struct amiga_floppy_struct unit[FD_MAX_UNITS];
  
  static struct timer_list flush_track_timer[FD_MAX_UNITS];
  static struct timer_list post_write_timer;
  static struct timer_list motor_on_timer;
  static struct timer_list motor_off_timer[FD_MAX_UNITS];
  static int on_attempts;
  
  /* Synchronization of FDC access */
  /* request loop (trackbuffer) */
  static volatile int fdc_busy = -1;
  static volatile int fdc_nested;
  static DECLARE_WAIT_QUEUE_HEAD(fdc_wait);
   

  static DECLARE_COMPLETION(motor_on_completion);

  
  static volatile int selected = -1;	/* currently selected drive */
  
  static int writepending;
  static int writefromint;
  static char *raw_buf;

  static int fdc_queue;

  
  static DEFINE_SPINLOCK(amiflop_lock);
  
  #define RAW_BUF_SIZE 30000  /* size of raw disk data */
  
  /*
   * These are global variables, as that's the easiest way to give
   * information to interrupts. They are the data used for the current
   * request.
   */
  static volatile char block_flag;
  static DECLARE_WAIT_QUEUE_HEAD(wait_fd_block);
  
  /* MS-Dos MFM Coding tables (should go quick and easy) */
  static unsigned char mfmencode[16]={
  	0x2a, 0x29, 0x24, 0x25, 0x12, 0x11, 0x14, 0x15,
  	0x4a, 0x49, 0x44, 0x45, 0x52, 0x51, 0x54, 0x55
  };
  static unsigned char mfmdecode[128];
  
  /* floppy internal millisecond timer stuff */

  static DECLARE_COMPLETION(ms_wait_completion);

  #define MS_TICKS ((amiga_eclock+50)/1000)
  
  /*
   * 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

  #define custom amiga_custom

  /* Prevent "aliased" accesses. */
  static int fd_ref[4] = { 0,0,0,0 };
  static int fd_device[4] = { 0, 0, 0, 0 };
  
  /*
   * Here come the actual hardware access and helper functions.
   * They are not reentrant and single threaded because all drives
   * share the same hardware and the same trackbuffer.
   */
  
  /* Milliseconds timer */

  static irqreturn_t ms_isr(int irq, void *dummy)

  {

  	complete(&ms_wait_completion);

  	return IRQ_HANDLED;
  }
  
  /* all waits are queued up 
     A more generic routine would do a schedule a la timer.device */
  static void ms_delay(int ms)
  {

  	int ticks;

  	static DEFINE_MUTEX(mutex);

  	if (ms > 0) {

  		mutex_lock(&mutex);

  		ticks = MS_TICKS*ms-1;
  		ciaa.tblo=ticks%256;
  		ciaa.tbhi=ticks/256;
  		ciaa.crb=0x19; /*count eclock, force load, one-shoot, start */

  		wait_for_completion(&ms_wait_completion);
  		mutex_unlock(&mutex);

  	}
  }
  
  /* Hardware semaphore */
  
  /* returns true when we would get the semaphore */
  static inline int try_fdc(int drive)
  {
  	drive &= 3;
  	return ((fdc_busy < 0) || (fdc_busy == drive));
  }
  
  static void get_fdc(int drive)
  {
  	unsigned long flags;
  
  	drive &= 3;
  #ifdef DEBUG
  	printk("get_fdc: drive %d  fdc_busy %d  fdc_nested %d
  ",drive,fdc_busy,fdc_nested);
  #endif
  	local_irq_save(flags);

  	wait_event(fdc_wait, try_fdc(drive));

  	fdc_busy = drive;
  	fdc_nested++;
  	local_irq_restore(flags);
  }
  
  static inline void rel_fdc(void)
  {
  #ifdef DEBUG
  	if (fdc_nested == 0)
  		printk("fd: unmatched rel_fdc
  ");
  	printk("rel_fdc: fdc_busy %d fdc_nested %d
  ",fdc_busy,fdc_nested);
  #endif
  	fdc_nested--;
  	if (fdc_nested == 0) {
  		fdc_busy = -1;
  		wake_up(&fdc_wait);
  	}
  }
  
  static void fd_select (int drive)
  {
  	unsigned char prb = ~0;
  
  	drive&=3;
  #ifdef DEBUG
  	printk("selecting %d
  ",drive);
  #endif
  	if (drive == selected)
  		return;
  	get_fdc(drive);
  	selected = drive;
  
  	if (unit[drive].track % 2 != 0)
  		prb &= ~DSKSIDE;
  	if (unit[drive].motor == 1)
  		prb &= ~DSKMOTOR;
  	ciab.prb |= (SELMASK(0)|SELMASK(1)|SELMASK(2)|SELMASK(3));
  	ciab.prb = prb;
  	prb &= ~SELMASK(drive);
  	ciab.prb = prb;
  	rel_fdc();
  }
  
  static void fd_deselect (int drive)
  {
  	unsigned char prb;
  	unsigned long flags;
  
  	drive&=3;
  #ifdef DEBUG
  	printk("deselecting %d
  ",drive);
  #endif
  	if (drive != selected) {
  		printk(KERN_WARNING "Deselecting drive %d while %d was selected!
  ",drive,selected);
  		return;
  	}
  
  	get_fdc(drive);
  	local_irq_save(flags);
  
  	selected = -1;
  
  	prb = ciab.prb;
  	prb |= (SELMASK(0)|SELMASK(1)|SELMASK(2)|SELMASK(3));
  	ciab.prb = prb;
  
  	local_irq_restore (flags);
  	rel_fdc();
  
  }
  
  static void motor_on_callback(unsigned long nr)
  {
  	if (!(ciaa.pra & DSKRDY) || --on_attempts == 0) {

  		complete_all(&motor_on_completion);

  	} else {
  		motor_on_timer.expires = jiffies + HZ/10;
  		add_timer(&motor_on_timer);
  	}
  }
  
  static int fd_motor_on(int nr)
  {
  	nr &= 3;
  
  	del_timer(motor_off_timer + nr);
  
  	if (!unit[nr].motor) {
  		unit[nr].motor = 1;
  		fd_select(nr);

  		INIT_COMPLETION(motor_on_completion);

  		motor_on_timer.data = nr;
  		mod_timer(&motor_on_timer, jiffies + HZ/2);
  
  		on_attempts = 10;

  		wait_for_completion(&motor_on_completion);

  		fd_deselect(nr);
  	}
  
  	if (on_attempts == 0) {
  		on_attempts = -1;
  #if 0
  		printk (KERN_ERR "motor_on failed, turning motor off
  ");
  		fd_motor_off (nr);
  		return 0;
  #else
  		printk (KERN_WARNING "DSKRDY not set after 1.5 seconds - assuming drive is spinning notwithstanding
  ");
  #endif
  	}
  
  	return 1;
  }
  
  static void fd_motor_off(unsigned long drive)
  {
  	long calledfromint;
  #ifdef MODULE
  	long decusecount;
  
  	decusecount = drive & 0x40000000;
  #endif
  	calledfromint = drive & 0x80000000;
  	drive&=3;
  	if (calledfromint && !try_fdc(drive)) {
  		/* We would be blocked in an interrupt, so try again later */
  		motor_off_timer[drive].expires = jiffies + 1;
  		add_timer(motor_off_timer + drive);
  		return;
  	}
  	unit[drive].motor = 0;
  	fd_select(drive);
  	udelay (1);
  	fd_deselect(drive);
  }
  
  static void floppy_off (unsigned int nr)
  {
  	int drive;
  
  	drive = nr & 3;
  	/* called this way it is always from interrupt */
  	motor_off_timer[drive].data = nr | 0x80000000;
  	mod_timer(motor_off_timer + drive, jiffies + 3*HZ);
  }
  
  static int fd_calibrate(int drive)
  {
  	unsigned char prb;
  	int n;
  
  	drive &= 3;
  	get_fdc(drive);
  	if (!fd_motor_on (drive))
  		return 0;
  	fd_select (drive);
  	prb = ciab.prb;
  	prb |= DSKSIDE;
  	prb &= ~DSKDIREC;
  	ciab.prb = prb;
  	for (n = unit[drive].type->tracks/2; n != 0; --n) {
  		if (ciaa.pra & DSKTRACK0)
  			break;
  		prb &= ~DSKSTEP;
  		ciab.prb = prb;
  		prb |= DSKSTEP;
  		udelay (2);
  		ciab.prb = prb;
  		ms_delay(unit[drive].type->step_delay);
  	}
  	ms_delay (unit[drive].type->settle_time);
  	prb |= DSKDIREC;
  	n = unit[drive].type->tracks + 20;
  	for (;;) {
  		prb &= ~DSKSTEP;
  		ciab.prb = prb;
  		prb |= DSKSTEP;
  		udelay (2);
  		ciab.prb = prb;
  		ms_delay(unit[drive].type->step_delay + 1);
  		if ((ciaa.pra & DSKTRACK0) == 0)
  			break;
  		if (--n == 0) {
  			printk (KERN_ERR "fd%d: calibrate failed, turning motor off
  ", drive);
  			fd_motor_off (drive);
  			unit[drive].track = -1;
  			rel_fdc();
  			return 0;
  		}
  	}
  	unit[drive].track = 0;
  	ms_delay(unit[drive].type->settle_time);
  
  	rel_fdc();
  	fd_deselect(drive);
  	return 1;
  }
  
  static int fd_seek(int drive, int track)
  {
  	unsigned char prb;
  	int cnt;
  
  #ifdef DEBUG
  	printk("seeking drive %d to track %d
  ",drive,track);
  #endif
  	drive &= 3;
  	get_fdc(drive);
  	if (unit[drive].track == track) {
  		rel_fdc();
  		return 1;
  	}
  	if (!fd_motor_on(drive)) {
  		rel_fdc();
  		return 0;
  	}
  	if (unit[drive].track < 0 && !fd_calibrate(drive)) {
  		rel_fdc();
  		return 0;
  	}
  
  	fd_select (drive);
  	cnt = unit[drive].track/2 - track/2;
  	prb = ciab.prb;
  	prb |= DSKSIDE | DSKDIREC;
  	if (track % 2 != 0)
  		prb &= ~DSKSIDE;
  	if (cnt < 0) {
  		cnt = - cnt;
  		prb &= ~DSKDIREC;
  	}
  	ciab.prb = prb;
  	if (track % 2 != unit[drive].track % 2)
  		ms_delay (unit[drive].type->side_time);
  	unit[drive].track = track;
  	if (cnt == 0) {
  		rel_fdc();
  		fd_deselect(drive);
  		return 1;
  	}
  	do {
  		prb &= ~DSKSTEP;
  		ciab.prb = prb;
  		prb |= DSKSTEP;
  		udelay (1);
  		ciab.prb = prb;
  		ms_delay (unit[drive].type->step_delay);
  	} while (--cnt != 0);
  	ms_delay (unit[drive].type->settle_time);
  
  	rel_fdc();
  	fd_deselect(drive);
  	return 1;
  }
  
  static unsigned long fd_get_drive_id(int drive)
  {
  	int i;
  	ulong id = 0;
  
    	drive&=3;
    	get_fdc(drive);
  	/* set up for ID */
  	MOTOR_ON;
  	udelay(2);
  	SELECT(SELMASK(drive));
  	udelay(2);
  	DESELECT(SELMASK(drive));
  	udelay(2);
  	MOTOR_OFF;
  	udelay(2);
  	SELECT(SELMASK(drive));
  	udelay(2);
  	DESELECT(SELMASK(drive));
  	udelay(2);
  
  	/* loop and read disk ID */
  	for (i=0; i<32; i++) {
  		SELECT(SELMASK(drive));
  		udelay(2);
  
  		/* read and store value of DSKRDY */
  		id <<= 1;
  		id |= (ciaa.pra & DSKRDY) ? 0 : 1;	/* cia regs are low-active! */
  
  		DESELECT(SELMASK(drive));
  	}
  
  	rel_fdc();
  
          /*
           * RB: At least A500/A2000's df0: don't identify themselves.
           * As every (real) Amiga has at least a 3.5" DD drive as df0:
           * we default to that if df0: doesn't identify as a certain
           * type.
           */
          if(drive == 0 && id == FD_NODRIVE)
  	{
                  id = fd_def_df0;
                  printk(KERN_NOTICE "fd: drive 0 didn't identify, setting default %08lx
  ", (ulong)fd_def_df0);
  	}
  	/* return the ID value */
  	return (id);
  }

  static irqreturn_t fd_block_done(int irq, void *dummy)

  {
  	if (block_flag)
  		custom.dsklen = 0x4000;
  
  	if (block_flag == 2) { /* writing */
  		writepending = 2;
  		post_write_timer.expires = jiffies + 1; /* at least 2 ms */
  		post_write_timer.data = selected;
  		add_timer(&post_write_timer);
  	}
  	else {                /* reading */
  		block_flag = 0;
  		wake_up (&wait_fd_block);
  	}
  	return IRQ_HANDLED;
  }
  
  static void raw_read(int drive)
  {
  	drive&=3;
  	get_fdc(drive);

  	wait_event(wait_fd_block, !block_flag);

  	fd_select(drive);
  	/* setup adkcon bits correctly */
  	custom.adkcon = ADK_MSBSYNC;
  	custom.adkcon = ADK_SETCLR|ADK_WORDSYNC|ADK_FAST;
  
  	custom.dsksync = MFM_SYNC;
  
  	custom.dsklen = 0;
  	custom.dskptr = (u_char *)ZTWO_PADDR((u_char *)raw_buf);
  	custom.dsklen = unit[drive].type->read_size/sizeof(short) | DSKLEN_DMAEN;
  	custom.dsklen = unit[drive].type->read_size/sizeof(short) | DSKLEN_DMAEN;
  
  	block_flag = 1;

  	wait_event(wait_fd_block, !block_flag);

  
  	custom.dsklen = 0;
  	fd_deselect(drive);
  	rel_fdc();
  }
  
  static int raw_write(int drive)
  {
  	ushort adk;
  
  	drive&=3;
  	get_fdc(drive); /* corresponds to rel_fdc() in post_write() */
  	if ((ciaa.pra & DSKPROT) == 0) {
  		rel_fdc();
  		return 0;
  	}

  	wait_event(wait_fd_block, !block_flag);

  	fd_select(drive);
  	/* clear adkcon bits */
  	custom.adkcon = ADK_PRECOMP1|ADK_PRECOMP0|ADK_WORDSYNC|ADK_MSBSYNC;
  	/* set appropriate adkcon bits */
  	adk = ADK_SETCLR|ADK_FAST;
  	if ((ulong)unit[drive].track >= unit[drive].type->precomp2)
  		adk |= ADK_PRECOMP1;
  	else if ((ulong)unit[drive].track >= unit[drive].type->precomp1)
  		adk |= ADK_PRECOMP0;
  	custom.adkcon = adk;
  
  	custom.dsklen = DSKLEN_WRITE;
  	custom.dskptr = (u_char *)ZTWO_PADDR((u_char *)raw_buf);
  	custom.dsklen = unit[drive].type->write_size/sizeof(short) | DSKLEN_DMAEN|DSKLEN_WRITE;
  	custom.dsklen = unit[drive].type->write_size/sizeof(short) | DSKLEN_DMAEN|DSKLEN_WRITE;
  
  	block_flag = 2;
  	return 1;
  }
  
  /*
   * to be called at least 2ms after the write has finished but before any
   * other access to the hardware.
   */
  static void post_write (unsigned long drive)
  {
  #ifdef DEBUG
  	printk("post_write for drive %ld
  ",drive);
  #endif
  	drive &= 3;
  	custom.dsklen = 0;
  	block_flag = 0;
  	writepending = 0;
  	writefromint = 0;
  	unit[drive].dirty = 0;
  	wake_up(&wait_fd_block);
  	fd_deselect(drive);
  	rel_fdc(); /* corresponds to get_fdc() in raw_write */
  }
  
  
  /*
   * The following functions are to convert the block contents into raw data
   * written to disk and vice versa.
   * (Add other formats here ;-))
   */
  
  static unsigned long scan_sync(unsigned long raw, unsigned long end)
  {
  	ushort *ptr = (ushort *)raw, *endp = (ushort *)end;
  
  	while (ptr < endp && *ptr++ != 0x4489)
  		;
  	if (ptr < endp) {
  		while (*ptr == 0x4489 && ptr < endp)
  			ptr++;
  		return (ulong)ptr;
  	}
  	return 0;
  }
  
  static inline unsigned long checksum(unsigned long *addr, int len)
  {
  	unsigned long csum = 0;
  
  	len /= sizeof(*addr);
  	while (len-- > 0)
  		csum ^= *addr++;
  	csum = ((csum>>1) & 0x55555555)  ^  (csum & 0x55555555);
  
  	return csum;
  }
  
  static unsigned long decode (unsigned long *data, unsigned long *raw,
  			     int len)
  {
  	ulong *odd, *even;
  
  	/* convert length from bytes to longwords */
  	len >>= 2;
  	odd = raw;
  	even = odd + len;
  
  	/* prepare return pointer */
  	raw += len * 2;
  
  	do {
  		*data++ = ((*odd++ & 0x55555555) << 1) | (*even++ & 0x55555555);
  	} while (--len != 0);
  
  	return (ulong)raw;
  }
  
  struct header {
  	unsigned char magic;
  	unsigned char track;
  	unsigned char sect;
  	unsigned char ord;
  	unsigned char labels[16];
  	unsigned long hdrchk;
  	unsigned long datachk;
  };
  
  static int amiga_read(int drive)
  {
  	unsigned long raw;
  	unsigned long end;
  	int scnt;
  	unsigned long csum;
  	struct header hdr;
  
  	drive&=3;
  	raw = (long) raw_buf;
  	end = raw + unit[drive].type->read_size;
  
  	for (scnt = 0;scnt < unit[drive].dtype->sects * unit[drive].type->sect_mult; scnt++) {
  		if (!(raw = scan_sync(raw, end))) {
  			printk (KERN_INFO "can't find sync for sector %d
  ", scnt);
  			return MFM_NOSYNC;
  		}
  
  		raw = decode ((ulong *)&hdr.magic, (ulong *)raw, 4);
  		raw = decode ((ulong *)&hdr.labels, (ulong *)raw, 16);
  		raw = decode ((ulong *)&hdr.hdrchk, (ulong *)raw, 4);
  		raw = decode ((ulong *)&hdr.datachk, (ulong *)raw, 4);
  		csum = checksum((ulong *)&hdr,
  				(char *)&hdr.hdrchk-(char *)&hdr);
  
  #ifdef DEBUG
  		printk ("(%x,%d,%d,%d) (%lx,%lx,%lx,%lx) %lx %lx
  ",
  			hdr.magic, hdr.track, hdr.sect, hdr.ord,
  			*(ulong *)&hdr.labels[0], *(ulong *)&hdr.labels[4],
  			*(ulong *)&hdr.labels[8], *(ulong *)&hdr.labels[12],
  			hdr.hdrchk, hdr.datachk);
  #endif
  
  		if (hdr.hdrchk != csum) {
  			printk(KERN_INFO "MFM_HEADER: %08lx,%08lx
  ", hdr.hdrchk, csum);
  			return MFM_HEADER;
  		}
  
  		/* verify track */
  		if (hdr.track != unit[drive].track) {
  			printk(KERN_INFO "MFM_TRACK: %d, %d
  ", hdr.track, unit[drive].track);
  			return MFM_TRACK;
  		}
  
  		raw = decode ((ulong *)(unit[drive].trackbuf + hdr.sect*512),
  			      (ulong *)raw, 512);
  		csum = checksum((ulong *)(unit[drive].trackbuf + hdr.sect*512), 512);
  
  		if (hdr.datachk != csum) {
  			printk(KERN_INFO "MFM_DATA: (%x:%d:%d:%d) sc=%d %lx, %lx
  ",
  			       hdr.magic, hdr.track, hdr.sect, hdr.ord, scnt,
  			       hdr.datachk, csum);
  			printk (KERN_INFO "data=(%lx,%lx,%lx,%lx)
  ",
  				((ulong *)(unit[drive].trackbuf+hdr.sect*512))[0],
  				((ulong *)(unit[drive].trackbuf+hdr.sect*512))[1],
  				((ulong *)(unit[drive].trackbuf+hdr.sect*512))[2],
  				((ulong *)(unit[drive].trackbuf+hdr.sect*512))[3]);
  			return MFM_DATA;
  		}
  	}
  
  	return 0;
  }
  
  static void encode(unsigned long data, unsigned long *dest)
  {
  	unsigned long data2;
  
  	data &= 0x55555555;
  	data2 = data ^ 0x55555555;
  	data |= ((data2 >> 1) | 0x80000000) & (data2 << 1);
  
  	if (*(dest - 1) & 0x00000001)
  		data &= 0x7FFFFFFF;
  
  	*dest = data;
  }
  
  static void encode_block(unsigned long *dest, unsigned long *src, int len)
  {
  	int cnt, to_cnt = 0;
  	unsigned long data;
  
  	/* odd bits */
  	for (cnt = 0; cnt < len / 4; cnt++) {
  		data = src[cnt] >> 1;
  		encode(data, dest + to_cnt++);
  	}
  
  	/* even bits */
  	for (cnt = 0; cnt < len / 4; cnt++) {
  		data = src[cnt];
  		encode(data, dest + to_cnt++);
  	}
  }
  
  static unsigned long *putsec(int disk, unsigned long *raw, int cnt)
  {
  	struct header hdr;
  	int i;
  
  	disk&=3;
  	*raw = (raw[-1]&1) ? 0x2AAAAAAA : 0xAAAAAAAA;
  	raw++;
  	*raw++ = 0x44894489;
  
  	hdr.magic = 0xFF;
  	hdr.track = unit[disk].track;
  	hdr.sect = cnt;
  	hdr.ord = unit[disk].dtype->sects * unit[disk].type->sect_mult - cnt;
  	for (i = 0; i < 16; i++)
  		hdr.labels[i] = 0;
  	hdr.hdrchk = checksum((ulong *)&hdr,
  			      (char *)&hdr.hdrchk-(char *)&hdr);
  	hdr.datachk = checksum((ulong *)(unit[disk].trackbuf+cnt*512), 512);
  
  	encode_block(raw, (ulong *)&hdr.magic, 4);
  	raw += 2;
  	encode_block(raw, (ulong *)&hdr.labels, 16);
  	raw += 8;
  	encode_block(raw, (ulong *)&hdr.hdrchk, 4);
  	raw += 2;
  	encode_block(raw, (ulong *)&hdr.datachk, 4);
  	raw += 2;
  	encode_block(raw, (ulong *)(unit[disk].trackbuf+cnt*512), 512);
  	raw += 256;
  
  	return raw;
  }
  
  static void amiga_write(int disk)
  {
  	unsigned int cnt;
  	unsigned long *ptr = (unsigned long *)raw_buf;
  
  	disk&=3;
  	/* gap space */
  	for (cnt = 0; cnt < 415 * unit[disk].type->sect_mult; cnt++)
  		*ptr++ = 0xaaaaaaaa;
  
  	/* sectors */
  	for (cnt = 0; cnt < unit[disk].dtype->sects * unit[disk].type->sect_mult; cnt++)
  		ptr = putsec (disk, ptr, cnt);
  	*(ushort *)ptr = (ptr[-1]&1) ? 0x2AA8 : 0xAAA8;
  }
  
  
  struct dos_header {
  	unsigned char track,   /* 0-80 */
  		side,    /* 0-1 */
  		sec,     /* 0-...*/
  		len_desc;/* 2 */
  	unsigned short crc;     /* on 68000 we got an alignment problem, 
  				   but this compiler solves it  by adding silently 
  				   adding a pad byte so data won't fit
  				   and this took about 3h to discover.... */
  	unsigned char gap1[22];     /* for longword-alignedness (0x4e) */
  };
  
  /* crc routines are borrowed from the messydos-handler  */
  
  /* excerpt from the messydos-device           
  ; The CRC is computed not only over the actual data, but including
  ; the SYNC mark (3 * $a1) and the 'ID/DATA - Address Mark' ($fe/$fb).
  ; As we don't read or encode these fields into our buffers, we have to
  ; preload the registers containing the CRC with the values they would have
  ; after stepping over these fields.
  ;
  ; How CRCs "really" work:
  ;
  ; First, you should regard a bitstring as a series of coefficients of
  ; polynomials. We calculate with these polynomials in modulo-2
  ; arithmetic, in which both add and subtract are done the same as
  ; exclusive-or. Now, we modify our data (a very long polynomial) in
  ; such a way that it becomes divisible by the CCITT-standard 16-bit
  ;		 16   12   5
  ; polynomial:	x  + x	+ x + 1, represented by $11021. The easiest
  ; way to do this would be to multiply (using proper arithmetic) our
  ; datablock with $11021. So we have:
  ;   data * $11021		 =
  ;   data * ($10000 + $1021)      =
  ;   data * $10000 + data * $1021
  ; The left part of this is simple: Just add two 0 bytes. But then
  ; the right part (data $1021) remains difficult and even could have
  ; a carry into the left part. The solution is to use a modified
  ; multiplication, which has a result that is not correct, but with
  ; a difference of any multiple of $11021. We then only need to keep
  ; the 16 least significant bits of the result.
  ;
  ; The following algorithm does this for us:
  ;
  ;   unsigned char *data, c, crclo, crchi;
  ;   while (not done) {
  ;	c = *data++ + crchi;
  ;	crchi = (@ c) >> 8 + crclo;
  ;	crclo = @ c;
  ;   }
  ;
  ; Remember, + is done with EOR, the @ operator is in two tables (high
  ; and low byte separately), which is calculated as
  ;
  ;      $1021 * (c & $F0)
  ;  xor $1021 * (c & $0F)
  ;  xor $1021 * (c >> 4)         (* is regular multiplication)
  ;
  ;
  ; Anyway, the end result is the same as the remainder of the division of
  ; the data by $11021. I am afraid I need to study theory a bit more...
  
  
  my only works was to code this from manx to C....
  
  */
  
  static ushort dos_crc(void * data_a3, int data_d0, int data_d1, int data_d3)
  {
  	static unsigned char CRCTable1[] = {
  		0x00,0x10,0x20,0x30,0x40,0x50,0x60,0x70,0x81,0x91,0xa1,0xb1,0xc1,0xd1,0xe1,0xf1,
  		0x12,0x02,0x32,0x22,0x52,0x42,0x72,0x62,0x93,0x83,0xb3,0xa3,0xd3,0xc3,0xf3,0xe3,
  		0x24,0x34,0x04,0x14,0x64,0x74,0x44,0x54,0xa5,0xb5,0x85,0x95,0xe5,0xf5,0xc5,0xd5,
  		0x36,0x26,0x16,0x06,0x76,0x66,0x56,0x46,0xb7,0xa7,0x97,0x87,0xf7,0xe7,0xd7,0xc7,
  		0x48,0x58,0x68,0x78,0x08,0x18,0x28,0x38,0xc9,0xd9,0xe9,0xf9,0x89,0x99,0xa9,0xb9,
  		0x5a,0x4a,0x7a,0x6a,0x1a,0x0a,0x3a,0x2a,0xdb,0xcb,0xfb,0xeb,0x9b,0x8b,0xbb,0xab,
  		0x6c,0x7c,0x4c,0x5c,0x2c,0x3c,0x0c,0x1c,0xed,0xfd,0xcd,0xdd,0xad,0xbd,0x8d,0x9d,
  		0x7e,0x6e,0x5e,0x4e,0x3e,0x2e,0x1e,0x0e,0xff,0xef,0xdf,0xcf,0xbf,0xaf,0x9f,0x8f,
  		0x91,0x81,0xb1,0xa1,0xd1,0xc1,0xf1,0xe1,0x10,0x00,0x30,0x20,0x50,0x40,0x70,0x60,
  		0x83,0x93,0xa3,0xb3,0xc3,0xd3,0xe3,0xf3,0x02,0x12,0x22,0x32,0x42,0x52,0x62,0x72,
  		0xb5,0xa5,0x95,0x85,0xf5,0xe5,0xd5,0xc5,0x34,0x24,0x14,0x04,0x74,0x64,0x54,0x44,
  		0xa7,0xb7,0x87,0x97,0xe7,0xf7,0xc7,0xd7,0x26,0x36,0x06,0x16,0x66,0x76,0x46,0x56,
  		0xd9,0xc9,0xf9,0xe9,0x99,0x89,0xb9,0xa9,0x58,0x48,0x78,0x68,0x18,0x08,0x38,0x28,
  		0xcb,0xdb,0xeb,0xfb,0x8b,0x9b,0xab,0xbb,0x4a,0x5a,0x6a,0x7a,0x0a,0x1a,0x2a,0x3a,
  		0xfd,0xed,0xdd,0xcd,0xbd,0xad,0x9d,0x8d,0x7c,0x6c,0x5c,0x4c,0x3c,0x2c,0x1c,0x0c,
  		0xef,0xff,0xcf,0xdf,0xaf,0xbf,0x8f,0x9f,0x6e,0x7e,0x4e,0x5e,0x2e,0x3e,0x0e,0x1e
  	};
  
  	static unsigned char CRCTable2[] = {
  		0x00,0x21,0x42,0x63,0x84,0xa5,0xc6,0xe7,0x08,0x29,0x4a,0x6b,0x8c,0xad,0xce,0xef,
  		0x31,0x10,0x73,0x52,0xb5,0x94,0xf7,0xd6,0x39,0x18,0x7b,0x5a,0xbd,0x9c,0xff,0xde,
  		0x62,0x43,0x20,0x01,0xe6,0xc7,0xa4,0x85,0x6a,0x4b,0x28,0x09,0xee,0xcf,0xac,0x8d,
  		0x53,0x72,0x11,0x30,0xd7,0xf6,0x95,0xb4,0x5b,0x7a,0x19,0x38,0xdf,0xfe,0x9d,0xbc,
  		0xc4,0xe5,0x86,0xa7,0x40,0x61,0x02,0x23,0xcc,0xed,0x8e,0xaf,0x48,0x69,0x0a,0x2b,
  		0xf5,0xd4,0xb7,0x96,0x71,0x50,0x33,0x12,0xfd,0xdc,0xbf,0x9e,0x79,0x58,0x3b,0x1a,
  		0xa6,0x87,0xe4,0xc5,0x22,0x03,0x60,0x41,0xae,0x8f,0xec,0xcd,0x2a,0x0b,0x68,0x49,
  		0x97,0xb6,0xd5,0xf4,0x13,0x32,0x51,0x70,0x9f,0xbe,0xdd,0xfc,0x1b,0x3a,0x59,0x78,
  		0x88,0xa9,0xca,0xeb,0x0c,0x2d,0x4e,0x6f,0x80,0xa1,0xc2,0xe3,0x04,0x25,0x46,0x67,
  		0xb9,0x98,0xfb,0xda,0x3d,0x1c,0x7f,0x5e,0xb1,0x90,0xf3,0xd2,0x35,0x14,0x77,0x56,
  		0xea,0xcb,0xa8,0x89,0x6e,0x4f,0x2c,0x0d,0xe2,0xc3,0xa0,0x81,0x66,0x47,0x24,0x05,
  		0xdb,0xfa,0x99,0xb8,0x5f,0x7e,0x1d,0x3c,0xd3,0xf2,0x91,0xb0,0x57,0x76,0x15,0x34,
  		0x4c,0x6d,0x0e,0x2f,0xc8,0xe9,0x8a,0xab,0x44,0x65,0x06,0x27,0xc0,0xe1,0x82,0xa3,
  		0x7d,0x5c,0x3f,0x1e,0xf9,0xd8,0xbb,0x9a,0x75,0x54,0x37,0x16,0xf1,0xd0,0xb3,0x92,
  		0x2e,0x0f,0x6c,0x4d,0xaa,0x8b,0xe8,0xc9,0x26,0x07,0x64,0x45,0xa2,0x83,0xe0,0xc1,
  		0x1f,0x3e,0x5d,0x7c,0x9b,0xba,0xd9,0xf8,0x17,0x36,0x55,0x74,0x93,0xb2,0xd1,0xf0
  	};
  
  /* look at the asm-code - what looks in C a bit strange is almost as good as handmade */
  	register int i;
  	register unsigned char *CRCT1, *CRCT2, *data, c, crch, crcl;
  
  	CRCT1=CRCTable1;
  	CRCT2=CRCTable2;
  	data=data_a3;
  	crcl=data_d1;
  	crch=data_d0;
  	for (i=data_d3; i>=0; i--) {
  		c = (*data++) ^ crch;
  		crch = CRCT1[c] ^ crcl;
  		crcl = CRCT2[c];
  	}
  	return (crch<<8)|crcl;
  }
  
  static inline ushort dos_hdr_crc (struct dos_header *hdr)
  {
  	return dos_crc(&(hdr->track), 0xb2, 0x30, 3); /* precomputed magic */
  }
  
  static inline ushort dos_data_crc(unsigned char *data)
  {
  	return dos_crc(data, 0xe2, 0x95 ,511); /* precomputed magic */
  }
  
  static inline unsigned char dos_decode_byte(ushort word)
  {
  	register ushort w2;
  	register unsigned char byte;
  	register unsigned char *dec = mfmdecode;
  
  	w2=word;
  	w2>>=8;
  	w2&=127;
  	byte = dec[w2];
  	byte <<= 4;
  	w2 = word & 127;
  	byte |= dec[w2];
  	return byte;
  }
  
  static unsigned long dos_decode(unsigned char *data, unsigned short *raw, int len)
  {
  	int i;
  
  	for (i = 0; i < len; i++)
  		*data++=dos_decode_byte(*raw++);
  	return ((ulong)raw);
  }
  
  #ifdef DEBUG
  static void dbg(unsigned long ptr)
  {
  	printk("raw data @%08lx: %08lx, %08lx ,%08lx, %08lx
  ", ptr,
  	       ((ulong *)ptr)[0], ((ulong *)ptr)[1],
  	       ((ulong *)ptr)[2], ((ulong *)ptr)[3]);
  }
  #endif
  
  static int dos_read(int drive)
  {
  	unsigned long end;
  	unsigned long raw;
  	int scnt;
  	unsigned short crc,data_crc[2];
  	struct dos_header hdr;
  
  	drive&=3;
  	raw = (long) raw_buf;
  	end = raw + unit[drive].type->read_size;
  
  	for (scnt=0; scnt < unit[drive].dtype->sects * unit[drive].type->sect_mult; scnt++) {
  		do { /* search for the right sync of each sec-hdr */
  			if (!(raw = scan_sync (raw, end))) {
  				printk(KERN_INFO "dos_read: no hdr sync on "
  				       "track %d, unit %d for sector %d
  ",
  				       unit[drive].track,drive,scnt);
  				return MFM_NOSYNC;
  			}
  #ifdef DEBUG
  			dbg(raw);
  #endif
  		} while (*((ushort *)raw)!=0x5554); /* loop usually only once done */
  		raw+=2; /* skip over headermark */
  		raw = dos_decode((unsigned char *)&hdr,(ushort *) raw,8);
  		crc = dos_hdr_crc(&hdr);
  
  #ifdef DEBUG
  		printk("(%3d,%d,%2d,%d) %x
  ", hdr.track, hdr.side,
  		       hdr.sec, hdr.len_desc, hdr.crc);
  #endif
  
  		if (crc != hdr.crc) {
  			printk(KERN_INFO "dos_read: MFM_HEADER %04x,%04x
  ",
  			       hdr.crc, crc);
  			return MFM_HEADER;
  		}
  		if (hdr.track != unit[drive].track/unit[drive].type->heads) {
  			printk(KERN_INFO "dos_read: MFM_TRACK %d, %d
  ",
  			       hdr.track,
  			       unit[drive].track/unit[drive].type->heads);
  			return MFM_TRACK;
  		}
  
  		if (hdr.side != unit[drive].track%unit[drive].type->heads) {
  			printk(KERN_INFO "dos_read: MFM_SIDE %d, %d
  ",
  			       hdr.side,
  			       unit[drive].track%unit[drive].type->heads);
  			return MFM_TRACK;
  		}
  
  		if (hdr.len_desc != 2) {
  			printk(KERN_INFO "dos_read: unknown sector len "
  			       "descriptor %d
  ", hdr.len_desc);
  			return MFM_DATA;
  		}
  #ifdef DEBUG
  		printk("hdr accepted
  ");
  #endif
  		if (!(raw = scan_sync (raw, end))) {
  			printk(KERN_INFO "dos_read: no data sync on track "
  			       "%d, unit %d for sector%d, disk sector %d
  ",
  			       unit[drive].track, drive, scnt, hdr.sec);
  			return MFM_NOSYNC;
  		}
  #ifdef DEBUG
  		dbg(raw);
  #endif
  
  		if (*((ushort *)raw)!=0x5545) {
  			printk(KERN_INFO "dos_read: no data mark after "
  			       "sync (%d,%d,%d,%d) sc=%d
  ",
  			       hdr.track,hdr.side,hdr.sec,hdr.len_desc,scnt);
  			return MFM_NOSYNC;
  		}
  
  		raw+=2;  /* skip data mark (included in checksum) */
  		raw = dos_decode((unsigned char *)(unit[drive].trackbuf + (hdr.sec - 1) * 512), (ushort *) raw, 512);
  		raw = dos_decode((unsigned char  *)data_crc,(ushort *) raw,4);
  		crc = dos_data_crc(unit[drive].trackbuf + (hdr.sec - 1) * 512);
  
  		if (crc != data_crc[0]) {
  			printk(KERN_INFO "dos_read: MFM_DATA (%d,%d,%d,%d) "
  			       "sc=%d, %x %x
  ", hdr.track, hdr.side,
  			       hdr.sec, hdr.len_desc, scnt,data_crc[0], crc);
  			printk(KERN_INFO "data=(%lx,%lx,%lx,%lx,...)
  ",
  			       ((ulong *)(unit[drive].trackbuf+(hdr.sec-1)*512))[0],
  			       ((ulong *)(unit[drive].trackbuf+(hdr.sec-1)*512))[1],
  			       ((ulong *)(unit[drive].trackbuf+(hdr.sec-1)*512))[2],
  			       ((ulong *)(unit[drive].trackbuf+(hdr.sec-1)*512))[3]);
  			return MFM_DATA;
  		}
  	}
  	return 0;
  }
  
  static inline ushort dos_encode_byte(unsigned char byte)
  {
  	register unsigned char *enc, b2, b1;
  	register ushort word;
  
  	enc=mfmencode;
  	b1=byte;
  	b2=b1>>4;
  	b1&=15;
  	word=enc[b2] <<8 | enc [b1];
  	return (word|((word&(256|64)) ? 0: 128));
  }
  
  static void dos_encode_block(ushort *dest, unsigned char *src, int len)
  {
  	int i;
  
  	for (i = 0; i < len; i++) {
  		*dest=dos_encode_byte(*src++);
  		*dest|=((dest[-1]&1)||(*dest&0x4000))? 0: 0x8000;
  		dest++;
  	}
  }
  
  static unsigned long *ms_putsec(int drive, unsigned long *raw, int cnt)
  {
  	static struct dos_header hdr={0,0,0,2,0,
  	  {78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78,78}};
  	int i;
  	static ushort crc[2]={0,0x4e4e};
  
  	drive&=3;
  /* id gap 1 */
  /* the MFM word before is always 9254 */
  	for(i=0;i<6;i++)
  		*raw++=0xaaaaaaaa;
  /* 3 sync + 1 headermark */
  	*raw++=0x44894489;
  	*raw++=0x44895554;
  
  /* fill in the variable parts of the header */
  	hdr.track=unit[drive].track/unit[drive].type->heads;
  	hdr.side=unit[drive].track%unit[drive].type->heads;
  	hdr.sec=cnt+1;
  	hdr.crc=dos_hdr_crc(&hdr);
  
  /* header (without "magic") and id gap 2*/
  	dos_encode_block((ushort *)raw,(unsigned char *) &hdr.track,28);
  	raw+=14;
  
  /*id gap 3 */
  	for(i=0;i<6;i++)
  		*raw++=0xaaaaaaaa;
  
  /* 3 syncs and 1 datamark */
  	*raw++=0x44894489;
  	*raw++=0x44895545;
  
  /* data */
  	dos_encode_block((ushort *)raw,
  			 (unsigned char *)unit[drive].trackbuf+cnt*512,512);
  	raw+=256;
  
  /*data crc + jd's special gap (long words :-/) */
  	crc[0]=dos_data_crc(unit[drive].trackbuf+cnt*512);
  	dos_encode_block((ushort *) raw,(unsigned char *)crc,4);
  	raw+=2;
  
  /* data gap */
  	for(i=0;i<38;i++)
  		*raw++=0x92549254;
  
  	return raw; /* wrote 652 MFM words */
  }
  
  static void dos_write(int disk)
  {
  	int cnt;
  	unsigned long raw = (unsigned long) raw_buf;
  	unsigned long *ptr=(unsigned long *)raw;
  
  	disk&=3;
  /* really gap4 + indexgap , but we write it first and round it up */
  	for (cnt=0;cnt<425;cnt++)
  		*ptr++=0x92549254;
  
  /* the following is just guessed */
  	if (unit[disk].type->sect_mult==2)  /* check for HD-Disks */
  		for(cnt=0;cnt<473;cnt++)
  			*ptr++=0x92549254;
  
  /* now the index marks...*/
  	for (cnt=0;cnt<20;cnt++)
  		*ptr++=0x92549254;
  	for (cnt=0;cnt<6;cnt++)
  		*ptr++=0xaaaaaaaa;
  	*ptr++=0x52245224;
  	*ptr++=0x52245552;
  	for (cnt=0;cnt<20;cnt++)
  		*ptr++=0x92549254;
  
  /* sectors */
  	for(cnt = 0; cnt < unit[disk].dtype->sects * unit[disk].type->sect_mult; cnt++)
  		ptr=ms_putsec(disk,ptr,cnt);
  
  	*(ushort *)ptr = 0xaaa8; /* MFM word before is always 0x9254 */
  }
  
  /*
   * Here comes the high level stuff (i.e. the filesystem interface)
   * and helper functions.
   * Normally this should be the only part that has to be adapted to
   * different kernel versions.
   */
  
  /* FIXME: this assumes the drive is still spinning -
   * which is only true if we complete writing a track within three seconds
   */
  static void flush_track_callback(unsigned long nr)
  {
  	nr&=3;
  	writefromint = 1;
  	if (!try_fdc(nr)) {
  		/* we might block in an interrupt, so try again later */
  		flush_track_timer[nr].expires = jiffies + 1;
  		add_timer(flush_track_timer + nr);
  		return;
  	}
  	get_fdc(nr);
  	(*unit[nr].dtype->write_fkt)(nr);
  	if (!raw_write(nr)) {
  		printk (KERN_NOTICE "floppy disk write protected
  ");
  		writefromint = 0;
  		writepending = 0;
  	}
  	rel_fdc();
  }
  
  static int non_int_flush_track (unsigned long nr)
  {
  	unsigned long flags;
  
  	nr&=3;
  	writefromint = 0;
  	del_timer(&post_write_timer);
  	get_fdc(nr);
  	if (!fd_motor_on(nr)) {
  		writepending = 0;
  		rel_fdc();
  		return 0;
  	}
  	local_irq_save(flags);
  	if (writepending != 2) {
  		local_irq_restore(flags);
  		(*unit[nr].dtype->write_fkt)(nr);
  		if (!raw_write(nr)) {
  			printk (KERN_NOTICE "floppy disk write protected "
  				"in write!
  ");
  			writepending = 0;
  			return 0;
  		}

  		wait_event(wait_fd_block, block_flag != 2);

  	}
  	else {
  		local_irq_restore(flags);
  		ms_delay(2); /* 2 ms post_write delay */
  		post_write(nr);
  	}
  	rel_fdc();
  	return 1;
  }
  
  static int get_track(int drive, int track)
  {
  	int error, errcnt;
  
  	drive&=3;
  	if (unit[drive].track == track)
  		return 0;
  	get_fdc(drive);
  	if (!fd_motor_on(drive)) {
  		rel_fdc();
  		return -1;
  	}
  
  	if (unit[drive].dirty == 1) {
  		del_timer (flush_track_timer + drive);
  		non_int_flush_track (drive);
  	}
  	errcnt = 0;
  	while (errcnt < MAX_ERRORS) {
  		if (!fd_seek(drive, track))
  			return -1;
  		raw_read(drive);
  		error = (*unit[drive].dtype->read_fkt)(drive);
  		if (error == 0) {
  			rel_fdc();
  			return 0;
  		}
  		/* Read Error Handling: recalibrate and try again */
  		unit[drive].track = -1;
  		errcnt++;
  	}
  	rel_fdc();
  	return -1;
  }

  /*
   * Round-robin between our available drives, doing one request from each
   */
  static struct request *set_next_request(void)
  {
  	struct request_queue *q;
  	int cnt = FD_MAX_UNITS;

  	struct request *rq = NULL;

  
  	/* Find next queue we can dispatch from */
  	fdc_queue = fdc_queue + 1;
  	if (fdc_queue == FD_MAX_UNITS)
  		fdc_queue = 0;

  	for(cnt = FD_MAX_UNITS; cnt > 0; cnt--) {

  
  		if (unit[fdc_queue].type->code == FD_NODRIVE) {
  			if (++fdc_queue == FD_MAX_UNITS)
  				fdc_queue = 0;

  			continue;

  		}
  
  		q = unit[fdc_queue].gendisk->queue;
  		if (q) {
  			rq = blk_fetch_request(q);
  			if (rq)
  				break;
  		}
  
  		if (++fdc_queue == FD_MAX_UNITS)
  			fdc_queue = 0;
  	}
  
  	return rq;
  }

  static void redo_fd_request(void)
  {

  	struct request *rq;

  	unsigned int cnt, block, track, sector;
  	int drive;
  	struct amiga_floppy_struct *floppy;
  	char *data;
  	unsigned long flags;

  	int err;

  next_req:

  	rq = set_next_request();

  	if (!rq) {

  		/* Nothing left to do */
  		return;
  	}

  	floppy = rq->rq_disk->private_data;

  	drive = floppy - unit;

  next_segment:

  	/* Here someone could investigate to be more efficient */

  	for (cnt = 0, err = 0; cnt < blk_rq_cur_sectors(rq); cnt++) {

  #ifdef DEBUG
  		printk("fd: sector %ld + %d requested for %s
  ",

  		       blk_rq_pos(rq), cnt,
  		       (rq_data_dir(rq) == READ) ? "read" : "write");

  #endif

  		block = blk_rq_pos(rq) + cnt;

  		if ((int)block > floppy->blocks) {

  			err = -EIO;
  			break;

  		}
  
  		track = block / (floppy->dtype->sects * floppy->type->sect_mult);
  		sector = block % (floppy->dtype->sects * floppy->type->sect_mult);

  		data = rq->buffer + 512 * cnt;

  #ifdef DEBUG
  		printk("access to track %d, sector %d, with buffer at "
  		       "0x%08lx
  ", track, sector, data);
  #endif

  		if (get_track(drive, track) == -1) {

  			err = -EIO;
  			break;

  		}

  		if (rq_data_dir(rq) == READ) {

  			memcpy(data, floppy->trackbuf + sector * 512, 512);

  		} else {

  			memcpy(floppy->trackbuf + sector * 512, data, 512);
  
  			/* keep the drive spinning while writes are scheduled */
  			if (!fd_motor_on(drive)) {

  				err = -EIO;
  				break;

  			}
  			/*
  			 * setup a callback to write the track buffer
  			 * after a short (1 tick) delay.
  			 */
  			local_irq_save(flags);
  
  			floppy->dirty = 1;
  		        /* reset the timer */
  			mod_timer (flush_track_timer + drive, jiffies + 1);
  			local_irq_restore(flags);

  		}
  	}

  	if (__blk_end_request_cur(rq, err))
  		goto next_segment;
  	goto next_req;

  }

  static void do_fd_request(struct request_queue * q)

  {
  	redo_fd_request();
  }

  static int fd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
  {
  	int drive = MINOR(bdev->bd_dev) & 3;
  
  	geo->heads = unit[drive].type->heads;
  	geo->sectors = unit[drive].dtype->sects * unit[drive].type->sect_mult;
  	geo->cylinders = unit[drive].type->tracks;
  	return 0;
  }

  static int fd_locked_ioctl(struct block_device *bdev, fmode_t mode,

  		    unsigned int cmd, unsigned long param)
  {

  	struct amiga_floppy_struct *p = bdev->bd_disk->private_data;
  	int drive = p - unit;

  	static struct floppy_struct getprm;

  	void __user *argp = (void __user *)param;

  
  	switch(cmd){

  	case FDFMTBEG:
  		get_fdc(drive);
  		if (fd_ref[drive] > 1) {
  			rel_fdc();
  			return -EBUSY;
  		}

  		fsync_bdev(bdev);

  		if (fd_motor_on(drive) == 0) {
  			rel_fdc();
  			return -ENODEV;
  		}
  		if (fd_calibrate(drive) == 0) {
  			rel_fdc();
  			return -ENXIO;
  		}
  		floppy_off(drive);
  		rel_fdc();
  		break;
  	case FDFMTTRK:

  		if (param < p->type->tracks * p->type->heads)

  		{
  			get_fdc(drive);
  			if (fd_seek(drive,param) != 0){

  				memset(p->trackbuf, FD_FILL_BYTE,
  				       p->dtype->sects * p->type->sect_mult * 512);

  				non_int_flush_track(drive);
  			}
  			floppy_off(drive);
  			rel_fdc();
  		}
  		else
  			return -EINVAL;
  		break;
  	case FDFMTEND:
  		floppy_off(drive);

  		invalidate_bdev(bdev);

  		break;
  	case FDGETPRM:
  		memset((void *)&getprm, 0, sizeof (getprm));

  		getprm.track=p->type->tracks;
  		getprm.head=p->type->heads;
  		getprm.sect=p->dtype->sects * p->type->sect_mult;
  		getprm.size=p->blocks;

  		if (copy_to_user(argp, &getprm, sizeof(struct floppy_struct)))

  			return -EFAULT;
  		break;
  	case FDSETPRM:
  	case FDDEFPRM:
  		return -EINVAL;
  	case FDFLUSH: /* unconditionally, even if not needed */
  		del_timer (flush_track_timer + drive);
  		non_int_flush_track(drive);
  		break;
  #ifdef RAW_IOCTL
  	case IOCTL_RAW_TRACK:

  		if (copy_to_user(argp, raw_buf, p->type->read_size))

  			return -EFAULT;
  		else

  			return p->type->read_size;

  #endif
  	default:
  		printk(KERN_DEBUG "fd_ioctl: unknown cmd %d for drive %d.",
  		       cmd, drive);
  		return -ENOSYS;
  	}
  	return 0;
  }

  static int fd_ioctl(struct block_device *bdev, fmode_t mode,
  			     unsigned int cmd, unsigned long param)
  {
  	int ret;

  	mutex_lock(&amiflop_mutex);

  	ret = fd_locked_ioctl(bdev, mode, cmd, param);

  	mutex_unlock(&amiflop_mutex);

  
  	return ret;
  }

  static void fd_probe(int dev)
  {
  	unsigned long code;
  	int type;
  	int drive;
  
  	drive = dev & 3;
  	code = fd_get_drive_id(drive);
  
  	/* get drive type */
  	for (type = 0; type < num_dr_types; type++)
  		if (drive_types[type].code == code)
  			break;
  
  	if (type >= num_dr_types) {
  		printk(KERN_WARNING "fd_probe: unsupported drive type "
  		       "%08lx found
  ", code);
  		unit[drive].type = &drive_types[num_dr_types-1]; /* FD_NODRIVE */
  		return;
  	}
  
  	unit[drive].type = drive_types + type;
  	unit[drive].track = -1;
  
  	unit[drive].disk = -1;
  	unit[drive].motor = 0;
  	unit[drive].busy = 0;
  	unit[drive].status = -1;
  }
  
  /*
   * 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 block_device *bdev, fmode_t mode)

  {

  	int drive = MINOR(bdev->bd_dev) & 3;
  	int system =  (MINOR(bdev->bd_dev) & 4) >> 2;

  	int old_dev;
  	unsigned long flags;

  	mutex_lock(&amiflop_mutex);

  	old_dev = fd_device[drive];

  	if (fd_ref[drive] && old_dev != system) {

  		mutex_unlock(&amiflop_mutex);

  		return -EBUSY;

  	}

  	if (mode & (FMODE_READ|FMODE_WRITE)) {
  		check_disk_change(bdev);
  		if (mode & FMODE_WRITE) {

  			int wrprot;
  
  			get_fdc(drive);
  			fd_select (drive);
  			wrprot = !(ciaa.pra & DSKPROT);
  			fd_deselect (drive);
  			rel_fdc();

  			if (wrprot) {

  				mutex_unlock(&amiflop_mutex);

  				return -EROFS;

  			}

  		}
  	}
  
  	local_irq_save(flags);
  	fd_ref[drive]++;
  	fd_device[drive] = system;
  	local_irq_restore(flags);
  
  	unit[drive].dtype=&data_types[system];
  	unit[drive].blocks=unit[drive].type->heads*unit[drive].type->tracks*
  		data_types[system].sects*unit[drive].type->sect_mult;
  	set_capacity(unit[drive].gendisk, unit[drive].blocks);
  
  	printk(KERN_INFO "fd%d: accessing %s-disk with %s-layout
  ",drive,
  	       unit[drive].type->name, data_types[system].name);

  	mutex_unlock(&amiflop_mutex);

  	return 0;
  }

  static int floppy_release(struct gendisk *disk, fmode_t mode)

  {

  	struct amiga_floppy_struct *p = disk->private_data;
  	int drive = p - unit;

  	mutex_lock(&amiflop_mutex);

  	if (unit[drive].dirty == 1) {
  		del_timer (flush_track_timer + drive);
  		non_int_flush_track (drive);
  	}
    
  	if (!fd_ref[drive]--) {
  		printk(KERN_CRIT "floppy_release with fd_ref == 0");
  		fd_ref[drive] = 0;
  	}
  #ifdef MODULE
  /* the mod_use counter is handled this way */
  	floppy_off (drive | 0x40000000);
  #endif

  	mutex_unlock(&amiflop_mutex);

  	return 0;
  }
  
  /*

   * check_events 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.
   */

  static unsigned amiga_check_events(struct gendisk *disk, unsigned int clearing)

  {
  	struct amiga_floppy_struct *p = disk->private_data;
  	int drive = p - unit;
  	int changed;
  	static int first_time = 1;
  
  	if (first_time)
  		changed = first_time--;
  	else {
  		get_fdc(drive);
  		fd_select (drive);
  		changed = !(ciaa.pra & DSKCHANGE);
  		fd_deselect (drive);
  		rel_fdc();
  	}
  
  	if (changed) {
  		fd_probe(drive);
  		p->track = -1;
  		p->dirty = 0;
  		writepending = 0; /* if this was true before, too bad! */
  		writefromint = 0;

  		return DISK_EVENT_MEDIA_CHANGE;

  	}
  	return 0;
  }

  static const struct block_device_operations floppy_fops = {

  	.owner		= THIS_MODULE,

  	.open		= floppy_open,
  	.release	= floppy_release,

  	.ioctl		= fd_ioctl,

  	.getgeo		= fd_getgeo,

  	.check_events	= amiga_check_events,

  };

  static int __init fd_probe_drives(void)
  {
  	int drive,drives,nomem;

  	printk(KERN_INFO "FD: probing units
  found ");

  	drives=0;
  	nomem=0;
  	for(drive=0;drive<FD_MAX_UNITS;drive++) {
  		struct gendisk *disk;
  		fd_probe(drive);
  		if (unit[drive].type->code == FD_NODRIVE)
  			continue;
  		disk = alloc_disk(1);
  		if (!disk) {
  			unit[drive].type->code = FD_NODRIVE;
  			continue;
  		}
  		unit[drive].gendisk = disk;

  
  		disk->queue = blk_init_queue(do_fd_request, &amiflop_lock);
  		if (!disk->queue) {
  			unit[drive].type->code = FD_NODRIVE;
  			continue;
  		}

  		drives++;
  		if ((unit[drive].trackbuf = kmalloc(FLOPPY_MAX_SECTORS * 512, GFP_KERNEL)) == NULL) {
  			printk("no mem for ");
  			unit[drive].type = &drive_types[num_dr_types - 1]; /* FD_NODRIVE */
  			drives--;
  			nomem = 1;
  		}
  		printk("fd%d ",drive);
  		disk->major = FLOPPY_MAJOR;
  		disk->first_minor = drive;
  		disk->fops = &floppy_fops;
  		sprintf(disk->disk_name, "fd%d", drive);
  		disk->private_data = &unit[drive];

  		set_capacity(disk, 880*2);
  		add_disk(disk);
  	}
  	if ((drives > 0) || (nomem == 0)) {
  		if (drives == 0)
  			printk("no drives");
  		printk("
  ");
  		return drives;
  	}
  	printk("
  ");
  	return -ENOMEM;
  }
   
  static struct kobject *floppy_find(dev_t dev, int *part, void *data)
  {
  	int drive = *part & 3;
  	if (unit[drive].type->code == FD_NODRIVE)
  		return NULL;
  	*part = 0;
  	return get_disk(unit[drive].gendisk);
  }

  static int __init amiga_floppy_probe(struct platform_device *pdev)

  {
  	int i, ret;

  	if (register_blkdev(FLOPPY_MAJOR,"fd"))
  		return -EBUSY;

  	ret = -ENOMEM;

  	raw_buf = amiga_chip_alloc(RAW_BUF_SIZE, "Floppy");
  	if (!raw_buf) {

  		printk("fd: cannot get chip mem buffer
  ");

  		goto out_blkdev;

  	}
  
  	ret = -EBUSY;
  	if (request_irq(IRQ_AMIGA_DSKBLK, fd_block_done, 0, "floppy_dma", NULL)) {
  		printk("fd: cannot get irq for dma
  ");
  		goto out_irq;
  	}
  
  	if (request_irq(IRQ_AMIGA_CIAA_TB, ms_isr, 0, "floppy_timer", NULL)) {
  		printk("fd: cannot get irq for timer
  ");
  		goto out_irq2;
  	}

  	ret = -ENODEV;

  	if (fd_probe_drives() < 1) /* No usable drives */
  		goto out_probe;
  
  	blk_register_region(MKDEV(FLOPPY_MAJOR, 0), 256, THIS_MODULE,
  				floppy_find, NULL, NULL);
  
  	/* initialize variables */
  	init_timer(&motor_on_timer);
  	motor_on_timer.expires = 0;
  	motor_on_timer.data = 0;
  	motor_on_timer.function = motor_on_callback;
  	for (i = 0; i < FD_MAX_UNITS; i++) {
  		init_timer(&motor_off_timer[i]);
  		motor_off_timer[i].expires = 0;
  		motor_off_timer[i].data = i|0x80000000;
  		motor_off_timer[i].function = fd_motor_off;
  		init_timer(&flush_track_timer[i]);
  		flush_track_timer[i].expires = 0;
  		flush_track_timer[i].data = i;
  		flush_track_timer[i].function = flush_track_callback;
  
  		unit[i].track = -1;
  	}
  
  	init_timer(&post_write_timer);
  	post_write_timer.expires = 0;
  	post_write_timer.data = 0;
  	post_write_timer.function = post_write;
    
  	for (i = 0; i < 128; i++)
  		mfmdecode[i]=255;
  	for (i = 0; i < 16; i++)
  		mfmdecode[mfmencode[i]]=i;
  
  	/* make sure that disk DMA is enabled */
  	custom.dmacon = DMAF_SETCLR | DMAF_DISK;
  
  	/* init ms timer */
  	ciaa.crb = 8; /* one-shot, stop */
  	return 0;
  
  out_probe:

  	free_irq(IRQ_AMIGA_CIAA_TB, NULL);
  out_irq2:
  	free_irq(IRQ_AMIGA_DSKBLK, NULL);
  out_irq:
  	amiga_chip_free(raw_buf);

  out_blkdev:
  	unregister_blkdev(FLOPPY_MAJOR,"fd");
  	return ret;
  }

  #if 0 /* not safe to unload */

  static int __exit amiga_floppy_remove(struct platform_device *pdev)

  {
  	int i;
  
  	for( i = 0; i < FD_MAX_UNITS; i++) {
  		if (unit[i].type->code != FD_NODRIVE) {

  			struct request_queue *q = unit[i].gendisk->queue;

  			del_gendisk(unit[i].gendisk);
  			put_disk(unit[i].gendisk);
  			kfree(unit[i].trackbuf);

  			if (q)
  				blk_cleanup_queue(q);

  		}
  	}
  	blk_unregister_region(MKDEV(FLOPPY_MAJOR, 0), 256);
  	free_irq(IRQ_AMIGA_CIAA_TB, NULL);
  	free_irq(IRQ_AMIGA_DSKBLK, NULL);
  	custom.dmacon = DMAF_DISK; /* disable DMA */
  	amiga_chip_free(raw_buf);

  	unregister_blkdev(FLOPPY_MAJOR, "fd");
  }
  #endif

  static struct platform_driver amiga_floppy_driver = {
  	.driver   = {
  		.name	= "amiga-floppy",
  		.owner	= THIS_MODULE,
  	},
  };
  
  static int __init amiga_floppy_init(void)
  {
  	return platform_driver_probe(&amiga_floppy_driver, amiga_floppy_probe);
  }
  
  module_init(amiga_floppy_init);
  
  #ifndef MODULE

  static int __init amiga_floppy_setup (char *str)
  {
  	int n;
  	if (!MACH_IS_AMIGA)
  		return 0;
  	if (!get_option(&str, &n))
  		return 0;
  	printk (KERN_INFO "amiflop: Setting default df0 to %x
  ", n);
  	fd_def_df0 = n;

  	return 1;

  }
  
  __setup("floppy=", amiga_floppy_setup);

  #endif

  
  MODULE_ALIAS("platform:amiga-floppy");