Import of Linux/MIPS 2.1.14

1 files changed, 1782 insertions, 0 deletions

diff --git a/drivers/block/amiflop.c b/drivers/block/amiflop.c
new file mode 100644
index 000000000..7afc22888
--- /dev/null
+++ b/drivers/block/amiflop.c
@@ -0,0 +1,1782 @@
+/*
+ *  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 1995 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.
+ *
+ *  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.
+ */
+
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/fcntl.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/fd.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/delay.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+
+#include <asm/amifdreg.h>
+#include <asm/amifd.h>
+#include <asm/amigahw.h>
+#include <asm/amigaints.h>
+#include <asm/irq.h>
+#include <asm/bootinfo.h>
+#include <asm/amigatypes.h>
+
+#define MAJOR_NR FLOPPY_MAJOR
+#include <linux/blk.h>
+
+#undef DEBUG /* print _LOTS_ of infos */
+
+#define RAW_IOCTL
+#ifdef RAW_IOCTL
+#define IOCTL_RAW_TRACK 0x5254524B  /* 'RTRK' */
+#endif
+
+/* prototypes */
+
+static int amiga_read(int,unsigned char *, unsigned long, int);
+static void amiga_write(int, unsigned long, unsigned char *, int);
+static int dos_read(int, unsigned char *, unsigned long, int);
+static void dos_write(int, unsigned long, unsigned char *,int);
+static ushort dos_crc(void *, int, int, int);
+static void fd_probe(int);
+
+
+/*
+ *  Defines
+ */
+#define MAX_SECTORS	22
+
+/*
+ *  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) */
+
+/*
+ *  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 int fd_def_df0 = 0;     /* default for df0 if it doesn't identify */
+
+
+/*
+ *  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)))
+
+#define DRIVE(x) ((x) & 3)
+#define PROBE(x) ((x) >> 2) & 1)
+#define TYPE(x)  ((x) >> 3) & 2)
+#define DATA(x)  ((x) >> 5) & 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", 160, 2, 14716, 13630, 1, 80,161, 3, 18, 1},
+ { FD_HD_3,	"HD 3.5", 160, 2, 28344, 27258, 2, 80,161, 3, 18, 1},
+ { FD_DD_5,	"DD 5.25", 80, 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 = sizeof(drive_types) / sizeof(drive_types[0]);
+
+/* defaults for 3 1/2" HD-Disks */
+static int floppy_sizes[256]={880,880,880,880,720,720,720,};
+static int floppy_blocksizes[256]={0,};
+/* hardsector size assumed to be 512 */
+
+static struct fd_data_type data_types[] = {
+  { "Amiga", 11 , amiga_read, amiga_write},
+  { "MS-Dos", 9, dos_read, dos_write}
+};
+static int num_da_types = sizeof(data_types) / sizeof(data_types[0]);
+
+/* current info on each unit */
+static struct amiga_floppy_struct unit[FD_MAX_UNITS];
+
+static struct timer_list flush_track_timer;
+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;
+
+/* track buffer */
+static int lastdrive = -1;
+static int savedtrack = -1;
+static int writepending = 0;
+static int writefromint = 0;
+static unsigned char trackdata[MAX_SECTORS * 512];
+static char *raw_buf;
+
+#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 char block_flag = 0;
+static int selected = 0;
+static struct wait_queue *wait_fd_block = NULL;
+
+/* Synchronization of FDC access. */
+static volatile int fdc_busy = 0;
+static struct wait_queue *fdc_wait = NULL;
+static struct wait_queue *motor_wait = NULL;
+
+/* 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 struct semaphore ms_sem = MUTEX;
+static struct wait_queue *ms_wait = NULL;
+#define MS_TICKS ((amiga_eclock+50)/1000)
+
+static void ms_isr(int irq, struct pt_regs *fp, void *dummy)
+{
+wake_up(&ms_wait);
+}
+
+/* with the semaphore waits are queued up 
+   A more generic routine would do a schedule a la timer.device */
+static void ms_delay(int ms)
+{
+  int ticks;
+  if (ms > 0) {
+    down(&ms_sem);
+    ticks=MS_TICKS*ms-1;
+    ciaa.tblo=ticks%256;
+    ciaa.tbhi=ticks/256;
+    ciaa.crb=0x19; /* count clock, force load, one-shot, start */
+    sleep_on(&ms_wait);
+    up(&ms_sem);
+  }
+}
+
+/*
+ * Functions
+ */
+/*======================================================================
+  Turn off the motor of the given drive.  Unit must already be active.
+  Returns standard floppy error code.
+======================================================================*/
+static void fd_motor_off(unsigned long drive)
+{
+	unsigned long flags;
+	unsigned char prb = ~0;
+
+	drive&=3;
+	save_flags(flags);
+	cli();
+
+	if (unit[drive].track % 2 != 0)
+		prb &= ~DSKSIDE;
+	ciab.prb |= (SELMASK(0)|SELMASK(1)|SELMASK(2)|SELMASK(3));
+	ciab.prb = prb;
+	prb &= ~SELMASK(drive);
+	ciab.prb = prb;
+	udelay (1);
+	prb |= (SELMASK(0)|SELMASK(1)|SELMASK(2)|SELMASK(3));
+	ciab.prb = prb;
+	selected = -1;
+	unit[drive].motor = 0;
+
+	restore_flags(flags);
+}
+
+static void motor_on_callback(unsigned long nr)
+{
+  nr &= 3;
+
+	if (!(ciaa.pra & DSKRDY) || --on_attempts == 0) {
+		unit[nr].motor = 1;
+		wake_up (&motor_wait);
+	} else {
+		motor_on_timer.expires = jiffies + HZ/10;
+		add_timer(&motor_on_timer);
+	}
+}
+
+static int motor_on(int nr)
+{
+	unsigned long flags;
+	unsigned char prb = ~0;
+
+	nr &= 3;
+	save_flags (flags);
+	cli();
+	del_timer(motor_off_timer + nr);
+
+	if (!unit[nr].motor) {
+		del_timer(&motor_on_timer);
+		motor_on_timer.data = nr;
+		motor_on_timer.expires = jiffies + HZ/2;
+		add_timer(&motor_on_timer);
+		on_attempts = 10;
+
+
+		prb &= ~DSKMOTOR;
+		if (unit[nr].track % 2 != 0)
+			prb &= ~DSKSIDE;
+		ciab.prb |= (SELMASK(0)|SELMASK(1)|SELMASK(2)|SELMASK(3));
+		ciab.prb = prb;
+		prb &= ~SELMASK(nr);
+		ciab.prb = prb;
+		selected = nr;
+
+		while (!unit[nr].motor)
+			sleep_on (&motor_wait);
+	}
+	restore_flags(flags);
+
+	if (on_attempts == 0) {
+		printk ("motor_on failed, turning motor off\n");
+		fd_motor_off (nr);
+		return 0;
+	}
+
+	return 1;
+}
+
+static void floppy_off (unsigned int nr)
+{
+	nr&=3;
+	del_timer(motor_off_timer+nr);
+	motor_off_timer[nr].expires = jiffies + 3*HZ;
+	add_timer(motor_off_timer+nr);
+}
+
+static void fd_select (int drive)
+{
+	unsigned char prb = ~0;
+
+	drive&=3;
+	if (drive == selected)
+		return;
+	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;
+}
+
+static void fd_deselect (int drive)
+{
+	unsigned char prb;
+	unsigned long flags;
+
+	drive&=3;
+	if (drive != selected)
+		return;
+
+	save_flags (flags);
+	sti();
+
+	selected = -1;
+
+	prb = ciab.prb;
+	prb |= (SELMASK(0)|SELMASK(1)|SELMASK(2)|SELMASK(3));
+	ciab.prb = prb;
+
+	restore_flags (flags);
+
+}
+
+/*======================================================================
+  Seek the drive to track 0.
+  The drive must be active and the motor must be running.
+  Returns standard floppy error code.
+======================================================================*/
+static int fd_calibrate(int drive)
+{
+	unsigned char prb;
+	int n;
+
+	drive &= 3;
+	if (!motor_on (drive))
+		return 0;
+	fd_select (drive);
+	prb = ciab.prb;
+	prb |= DSKSIDE;
+	prb &= ~DSKDIREC;
+	ciab.prb = prb;
+	for (n = unit[drive].type->tracks/4; n != 0; --n) {
+		if (ciaa.pra & DSKTRACK0)
+			break;
+		prb &= ~DSKSTEP;
+		ciab.prb = prb;
+		prb |= DSKSTEP;
+		ms_delay (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/2 + 20;
+	for (;;) {
+		prb &= ~DSKSTEP;
+		ciab.prb = prb;
+		prb |= DSKSTEP;
+		ms_delay (2);
+		ciab.prb = prb;
+		ms_delay(unit[drive].type->step_delay + 1);
+		if ((ciaa.pra & DSKTRACK0) == 0)
+			break;
+		if (--n == 0) {
+			printk ("calibrate failed, turning motor off\n");
+			fd_motor_off (drive);
+			unit[drive].track = -1;
+			return 0;
+		}
+	}
+	unit[drive].track = 0;
+	ms_delay(unit[drive].type->settle_time);
+
+	return 1;
+}
+
+/*======================================================================
+  Seek the drive to the requested cylinder.
+  The drive must have been calibrated at some point before this.
+  The drive must also be active and the motor must be running.
+======================================================================*/
+static int fd_seek(int drive, int track)
+{
+	unsigned char prb;
+	int cnt;
+
+	drive &= 3;
+	if (unit[drive].track == track)
+		return 1;
+	if (!motor_on(drive))
+		return 0;
+	fd_select (drive);
+	if (unit[drive].track < 0 && !fd_calibrate(drive))
+		return 0;
+
+	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)
+		return 1;
+	do {
+		prb &= ~DSKSTEP;
+		ciab.prb = prb;
+		prb |= DSKSTEP;
+		ms_delay (1);
+		ciab.prb = prb;
+		ms_delay (unit[drive].type->step_delay);
+	} while (--cnt != 0);
+	ms_delay (unit[drive].type->settle_time);
+
+	return 1;
+}
+
+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++);
+  }
+}
+
+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;
+}
+
+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 unsigned long *putsec(int disk, unsigned long *raw, int track, int cnt,
+			     unsigned char *data)
+{
+	struct header hdr;
+	int i;
+
+	if (!AMIGAHW_PRESENT(AMI_FLOPPY))
+	    return 0;
+
+	disk&=3;
+	*raw = (raw[-1]&1) ? 0x2AAAAAAA : 0xAAAAAAAA;
+	raw++;
+	*raw++ = 0x44894489;
+
+	hdr.magic = 0xFF;
+	hdr.track = track;
+	hdr.sect = cnt;
+	hdr.ord = unit[disk].sects-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 *)data, 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 *)data, 512);
+	raw += 256;
+
+	return raw;
+}
+
+
+/*==========================================================================
+  amiga_write converts track/labels data to raw track data
+==========================================================================*/
+static void amiga_write(int disk, unsigned long raw, unsigned char *data,
+			int track)
+{
+	int cnt;
+	unsigned long *ptr = (unsigned long *)raw;
+
+	disk&=3;
+	/* gap space */
+	for (cnt = 0; cnt < 415 * unit[disk].type->sect_mult; cnt++)
+		*ptr++ = 0xaaaaaaaa;
+
+	/* sectors */
+	for (cnt = 0; cnt < unit[disk].sects; cnt++)
+		ptr = putsec (disk, ptr, track, cnt, data + cnt*512);
+	*(ushort *)ptr = (ptr[-1]&1) ? 0x2AA8 : 0xAAA8;
+	raw = (unsigned long)ptr + 2;
+}
+
+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;
+}
+
+#define MFM_NOSYNC	1
+#define MFM_HEADER	2
+#define MFM_DATA	3
+#define MFM_TRACK	4
+
+/*==========================================================================
+ scan_sync - looks for the next start of sector marked by a sync. d3 is the
+		sector number (10..0). When d3 = 10, can't be certain of a
+		starting sync.
+==========================================================================*/
+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;
+}
+
+/*==========================================================================
+  amiga_read reads a raw track of data into a track buffer
+==========================================================================*/
+static int amiga_read(int drive, unsigned char *track_data,
+		      unsigned long raw, int track)
+{
+	unsigned long end;
+	int scnt;
+	unsigned long csum;
+	struct header hdr;
+
+	drive&=3;
+	end = raw + unit[drive].type->read_size;
+
+	for (scnt = 0;scnt < unit[drive].sects; scnt++) {
+		if (!(raw = scan_sync(raw, end))) {
+			printk ("can't find sync for sector %d\n", 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\n",
+			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("MFM_HEADER: %08lx,%08lx\n", hdr.hdrchk, csum);
+			return MFM_HEADER;
+		}
+
+		/* verify track */
+		if (hdr.track != track) {
+			printk("MFM_TRACK: %d, %d\n", hdr.track, track);
+			return MFM_TRACK;
+		}
+
+		raw = decode ((ulong *)(track_data + hdr.sect*512),
+			      (ulong *)raw, 512);
+		csum = checksum((ulong *)(track_data + hdr.sect*512), 512);
+
+		if (hdr.datachk != csum) {
+			printk("MFM_DATA: (%x:%d:%d:%d) sc=%d %lx, %lx\n",
+			       hdr.magic, hdr.track, hdr.sect, hdr.ord, scnt,
+			       hdr.datachk, csum);
+			printk ("data=(%lx,%lx,%lx,%lx)\n",
+				((ulong *)(track_data+hdr.sect*512))[0],
+				((ulong *)(track_data+hdr.sect*512))[1],
+				((ulong *)(track_data+hdr.sect*512))[2],
+				((ulong *)(track_data+hdr.sect*512))[3]);
+			return MFM_DATA;
+		}
+	}
+
+	return 0;
+}
+
+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 cost about 3h to discover.... */
+unsigned char gap1[22];     /* for longword-alignedness (0x4e) */
+};
+
+/* crc routines are borrowed from the messydos-handler  */
+
+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 */
+}
+
+/* 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 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\n",ptr,
+  ((ulong *)ptr)[0],((ulong *)ptr)[1],((ulong *)ptr)[2],((ulong *)ptr)[3]);
+}
+#endif
+
+/*******************************************************************
+   this reads a raw track of data into trackbuffer for ms-disks 
+*******************************************************************/
+static int dos_read(int drive, unsigned char *track_data,
+	unsigned long raw, int track)
+{
+  unsigned long end;
+  int scnt;
+  unsigned short crc,data_crc[2];
+  struct dos_header hdr;
+
+  drive&=3;
+  end = raw + unit[drive].type->read_size;
+
+  for (scnt=0;scnt<unit[drive].sects;scnt++) {
+  do { /* search for the right sync of each sec-hdr */
+    if (!(raw = scan_sync (raw, end))) {
+      printk("dos_read: no hdr sync on track %d, unit %d for sector %d\n",
+        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\n", hdr.track, hdr.side,
+     hdr.sec, hdr.len_desc, hdr.crc);
+#endif
+
+  if (crc != hdr.crc) {
+    printk("dos_read: MFM_HEADER %04x,%04x\n", hdr.crc, crc);
+    return MFM_HEADER;
+  }
+  if (hdr.track != track/unit[drive].type->heads) {
+    printk("dos_read: MFM_TRACK %d, %d\n", hdr.track,
+      track/unit[drive].type->heads);
+    return MFM_TRACK;
+  }
+
+  if (hdr.side != track%unit[drive].type->heads) {
+    printk("dos_read: MFM_SIDE %d, %d\n", hdr.side,
+      track%unit[drive].type->heads);
+    return MFM_TRACK;
+  }
+
+  if (hdr.len_desc != 2) {
+    printk("dos_read: unknown sector len descriptor %d\n", hdr.len_desc);
+    return MFM_DATA;
+  }
+#ifdef DEBUG
+  printk("hdr accepted\n");
+#endif
+  if (!(raw = scan_sync (raw, end))) {
+    printk("dos_read: no data sync on track %d, unit %d for sector%d, disk sector %d\n",
+      track, drive, scnt, hdr.sec);
+    return MFM_NOSYNC;
+  }
+#ifdef DEBUG
+  dbg(raw);
+#endif
+
+  if (*((ushort *)raw)!=0x5545) {
+    printk("dos_read: no data mark after sync (%d,%d,%d,%d) sc=%d\n",
+      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 *)(track_data + (hdr.sec - 1) * 512), (ushort *) raw, 512);
+  raw = dos_decode((unsigned char  *)data_crc,(ushort *) raw,4);
+  crc = dos_data_crc(track_data + (hdr.sec - 1) * 512);
+
+  if (crc != data_crc[0]) {
+    printk("dos_read: MFM_DATA (%d,%d,%d,%d) sc=%d, %x %x\n",
+      hdr.track, hdr.side, hdr.sec, hdr.len_desc,
+      scnt,data_crc[0], crc);
+    printk("data=(%lx,%lx,%lx,%lx,...)\n",
+      ((ulong *)(track_data+(hdr.sec-1)*512))[0],
+      ((ulong *)(track_data+(hdr.sec-1)*512))[1],
+      ((ulong *)(track_data+(hdr.sec-1)*512))[2],
+      ((ulong *)(track_data+(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 track, int cnt,
+   unsigned char *data)
+{
+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=track/unit[drive].type->heads;
+hdr.side=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 *)data,512);
+raw+=256;
+
+/*data crc + jd's special gap (long words :-/) */
+crc[0]=dos_data_crc(data);
+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 */
+}
+
+
+/**************************************************************
+  builds encoded track data from trackbuffer data
+**************************************************************/
+static void dos_write(int disk, unsigned long raw, unsigned char *data,
+    int track)
+{
+int cnt;
+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].sects;cnt++)
+  ptr=ms_putsec(disk,ptr,track,cnt,data+cnt*512);
+
+*(ushort *)ptr = 0xaaa8; /* MFM word before is always 0x9254 */
+}
+
+/*
+ * 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
+
+/*
+ * 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;
+
+/* Prevent "aliased" accesses. */
+static fd_ref[4] = { 0,0,0,0 };
+static fd_device[4] = { 0,0,0,0 };
+
+/*
+ * Current device number. Taken either from the block header or from the
+ * format request descriptor.
+ */
+#define CURRENT_DEVICE (CURRENT->rq_dev)
+
+/* Current error count. */
+#define CURRENT_ERRORS (CURRENT->errors)
+
+static void request_done(int uptodate)
+{
+  timer_active &= ~(1 << FLOPPY_TIMER);
+  end_request(uptodate);
+}
+
+/*
+ * 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.
+ */
+static int amiga_floppy_change(kdev_t dev)
+{
+	int drive = dev & 3;
+	int changed;
+
+	if (MAJOR(dev) != MAJOR_NR) {
+		printk("floppy_change: not a floppy\n");
+		return 0;
+	}
+
+	fd_select (drive);
+	changed = !(ciaa.pra & DSKCHANGE);
+	fd_deselect (drive);
+
+	if (changed) {
+		fd_probe(dev);
+		unit[drive].track = -1;
+		selected = -1;
+		savedtrack = -1;
+		writepending = 0; /* if this was true before, too bad! */
+		writefromint = 0;
+		return 1;
+	}
+	return 0;
+}
+
+static __inline__ void copy_buffer(void *from, void *to)
+{
+  ulong *p1,*p2;
+  int cnt;
+
+  p1 = (ulong *)from;
+  p2 = (ulong *)to;
+
+  for (cnt = 0; cnt < 512/4; cnt++)
+    *p2++ = *p1++;
+}
+
+static void raw_read(int drive, int track, char *ptrack, int len)
+{
+	drive&=3;
+	/* setup adkcon bits correctly */
+	custom.adkcon = ADK_MSBSYNC;
+	custom.adkcon = ADK_SETCLR|ADK_WORDSYNC|ADK_FAST;
+
+	custom.dsksync = MFM_SYNC;
+
+	custom.dsklen = 0;
+#if 0
+	ms_delay (unit[drive].type->side_time);
+#endif
+	custom.dskptr = (u_char *)ZTWO_PADDR((u_char *)ptrack);
+	custom.dsklen = len/sizeof(short) | DSKLEN_DMAEN;
+	custom.dsklen = len/sizeof(short) | DSKLEN_DMAEN;
+
+	block_flag = 1;
+
+	while (block_flag == 1)
+		sleep_on (&wait_fd_block);
+
+	custom.dsklen = 0;
+}
+
+static int raw_write(int drive, int track, char *ptrack, int len)
+{
+	ushort adk;
+
+	drive&=3;
+	if ((ciaa.pra & DSKPROT) == 0)
+		return 0;
+
+	/* clear adkcon bits */
+	custom.adkcon = ADK_PRECOMP1|ADK_PRECOMP0|ADK_WORDSYNC|ADK_MSBSYNC;
+	/* set appropriate adkcon bits */
+	adk = ADK_SETCLR|ADK_FAST;
+	if ((ulong)track >= unit[drive].type->precomp2)
+		adk |= ADK_PRECOMP1;
+	else if ((ulong)track >= unit[drive].type->precomp1)
+		adk |= ADK_PRECOMP0;
+	custom.adkcon = adk;
+
+	custom.dsklen = DSKLEN_WRITE;
+#if 0
+	ms_delay (unit[drive].type->side_time);
+#endif
+	custom.dskptr = (u_char *)ZTWO_PADDR((u_char *)ptrack);
+	custom.dsklen = len/sizeof(short) | DSKLEN_DMAEN|DSKLEN_WRITE;
+	custom.dsklen = len/sizeof(short) | DSKLEN_DMAEN|DSKLEN_WRITE;
+
+	block_flag = 2;
+	return 1;
+}
+
+static void post_write (unsigned long dummy)
+{
+  custom.dsklen = 0;
+  writepending = 0;
+  writefromint = 0;
+}
+
+static int get_track(int drive, int track)
+{
+	int error;
+
+	drive&=3;
+	if ((lastdrive == drive) && (savedtrack == track))
+		return 0;
+
+	lastdrive = drive;
+	raw_read(drive, track, raw_buf, unit[drive].type->read_size);
+	savedtrack = -1;
+	error = (*unit[drive].dtype->read_fkt)(drive, trackdata, (unsigned long)raw_buf, track);
+	switch (error) {
+	    case 0:
+		savedtrack = track;
+		return 0;
+	    case MFM_TRACK:
+		unit[drive].track = -1;
+		/* fall through */
+	    default:
+		return -1;
+	}
+}
+
+static void flush_track_callback(unsigned long nr)
+{
+  nr&=3;
+  writefromint = 1;
+  (*unit[nr].dtype->write_fkt)(nr, (unsigned long)raw_buf, trackdata, savedtrack);
+  if (!raw_write(nr, savedtrack, raw_buf, unit[nr].type->write_size)) {
+    printk ("floppy disk write protected\n");
+    writefromint = 0;
+    writepending = 0;
+  }
+}
+
+static int non_int_flush_track (unsigned long nr)
+{
+unsigned long flags;
+
+  nr&=3;
+  writefromint = 0;
+  del_timer(&post_write_timer);
+  save_flags(flags);
+  cli();
+  if (writepending != 2) {
+    restore_flags(flags);
+    (*unit[nr].dtype->write_fkt)(nr, (unsigned long)raw_buf, trackdata, savedtrack);
+    if (!raw_write(nr, savedtrack, raw_buf, unit[nr].type->write_size)) {
+      printk ("floppy disk write protected in write!\n");
+      writepending = 0;
+      return 0;
+    }
+    while (block_flag == 2)
+      sleep_on (&wait_fd_block);
+  }
+  else
+    restore_flags(flags);
+  ms_delay(2); /* 2 ms post_write delay */
+  post_write(0);
+  return 1;
+}
+
+static void redo_fd_request(void)
+{
+	unsigned int block, track, sector;
+	int device, drive, cnt;
+	struct amiga_floppy_struct *floppy;
+	char *data;
+	unsigned long flags;
+
+	if (CURRENT && CURRENT->rq_status == RQ_INACTIVE){
+		return;
+	}
+
+    repeat:
+	if (!CURRENT) {
+		if (!fdc_busy)
+			printk("FDC access conflict!");
+		fdc_busy = 0;
+		wake_up(&fdc_wait);
+		CLEAR_INTR;
+		return;
+	}
+
+	if (MAJOR(CURRENT->rq_dev) != MAJOR_NR)
+		panic(DEVICE_NAME ": request list destroyed");
+
+	if (CURRENT->bh && !buffer_locked(CURRENT->bh))
+		panic(DEVICE_NAME ": block not locked");
+
+	probing = 0;
+	device = MINOR(CURRENT_DEVICE);
+	if (device > 3) {
+		/* manual selection */
+		drive = device & 3;
+		floppy = unit + drive;
+	} else {
+		/* Auto-detection */
+		/* printk("redo_fd_request: can't handle auto detect\n");*/
+		/* printk("redo_fd_request: default to normal\n");*/
+		drive = device & 3;
+		floppy = unit + drive;
+	}
+
+	save_flags (flags);
+	cli();
+	if (drive != selected && writepending) {
+	  del_timer (&flush_track_timer);
+	  restore_flags (flags);
+	  if (!non_int_flush_track (selected)) {
+	    end_request(0);
+	    goto repeat;
+	  }
+	} else
+	  restore_flags (flags);
+
+ /* Here someone could investigate to be more efficient */
+	for (cnt = 0; cnt < CURRENT->current_nr_sectors; cnt++) { 
+#ifdef DEBUG
+		printk("fd: sector %d + %d requested\n",CURRENT->sector,cnt);
+#endif
+		block = CURRENT->sector + cnt;
+		if ((int)block > floppy->blocks) {
+			request_done(0);
+			goto repeat;
+		}
+
+		track = block / floppy->sects;
+		sector = block % floppy->sects;
+		data = CURRENT->buffer + 512 * cnt;
+
+		save_flags (flags);
+		cli();
+		if (track != savedtrack && writepending) {
+		  del_timer (&flush_track_timer);
+		  restore_flags (flags);
+		  if (!non_int_flush_track (selected)) {
+		    end_request(0);
+		    goto repeat;
+		  }
+		} else
+		  restore_flags (flags);
+
+		switch (CURRENT->cmd) {
+		    case READ:
+			if (!motor_on (drive)) {
+				end_request(0);
+				goto repeat;
+			}
+			fd_select (drive);
+			if (!fd_seek(drive, track)) {
+				end_request(0);
+				goto repeat;
+			}
+			if (get_track(drive, track) == -1) {
+				end_request(0);
+				goto repeat;
+			}
+			copy_buffer(trackdata + sector * 512, data);
+			break;
+
+		    case WRITE:
+			if (!motor_on (drive)) {
+				end_request(0);
+				goto repeat;
+			}
+			fd_select (drive);
+			if (!fd_seek(drive, track)) {
+				end_request(0);
+				goto repeat;
+			}
+			if (get_track(drive, track) == -1) {
+				end_request(0);
+				goto repeat;
+			}
+			copy_buffer(data, trackdata + sector * 512);
+			/*
+			 * setup a callback to write the track buffer
+			 * after a short (1 tick) delay.
+			 */
+			save_flags (flags);
+			cli();
+
+			if (writepending)
+			    /* reset the timer */
+			    del_timer (&flush_track_timer);
+			    
+			writepending = 1;
+			flush_track_timer.data = drive;
+			flush_track_timer.expires = jiffies + 1;
+			add_timer (&flush_track_timer);
+			restore_flags (flags);
+			break;
+
+		    default:
+			printk("do_fd_request: unknown command\n");
+			request_done(0);
+			goto repeat;
+		}
+	}
+	CURRENT->nr_sectors -= CURRENT->current_nr_sectors;
+	CURRENT->sector += CURRENT->current_nr_sectors;
+
+	request_done(1);
+	goto repeat;
+}
+
+static void do_fd_request(void)
+{
+unsigned long flags;
+
+	save_flags(flags);
+	cli();
+	while (fdc_busy) sleep_on(&fdc_wait);
+	fdc_busy = 1;
+	restore_flags(flags); /* sti(); */
+	redo_fd_request();
+}
+
+static int fd_ioctl(struct inode *inode, struct file *filp,
+		    unsigned int cmd, unsigned long param)
+{
+	int drive = inode->i_rdev & 3;
+	static struct floppy_struct getprm;
+	int error;
+
+	switch(cmd)
+	 {
+	  case FDFMTBEG:
+	    if (fd_ref[drive] > 1)
+	      return -EBUSY;
+	    fsync_dev(inode->i_rdev);
+	    if (motor_on(drive) == 0)
+	      return -ENODEV;
+	    if (fd_calibrate(drive) == 0)
+	      return -ENXIO;
+	    floppy_off(drive);
+	    break;
+	  case FDFMTTRK:
+	    if (param < unit[drive].type->tracks)
+	     {
+	      fd_select(drive);
+	      if (fd_seek(drive,param)!=0)
+	       {
+	        savedtrack=param;
+	        memset(trackdata,FD_FILL_BYTE,unit[drive].sects*512);
+	        non_int_flush_track(drive);
+	       }
+	      floppy_off(drive);
+	     }
+	    else
+	      return -EINVAL;
+	    break;
+	  case FDFMTEND:
+	    floppy_off(drive);
+	    invalidate_inodes(inode->i_rdev);
+	    invalidate_buffers(inode->i_rdev);
+	    break;
+	  case FDGETPRM:
+	    error = verify_area(VERIFY_WRITE, (void *)param,
+				sizeof(struct floppy_struct));
+	    if (error)
+	      return error;
+	    memset((void *)&getprm, 0, sizeof (getprm));
+	    getprm.track=unit[drive].type->tracks/unit[drive].type->heads;
+	    getprm.head=unit[drive].type->heads;
+	    getprm.sect=unit[drive].sects;
+	    getprm.size=unit[drive].blocks;
+	    copy_to_user((void *)param,(void *)&getprm,sizeof(struct floppy_struct));
+	    break;
+	  case BLKGETSIZE:
+            error = verify_area(VERIFY_WRITE, (void *)param,
+            			sizeof(long));
+            if (error)
+              return error;
+            put_fs_long(unit[drive].blocks,(long *)param);
+            break;
+          case FDSETPRM:
+          case FDDEFPRM:
+            return -EINVAL;
+          case FDFLUSH:
+            if ((drive == selected) && (writepending)) {
+              del_timer (&flush_track_timer);
+              non_int_flush_track(selected);
+            }
+            break;
+#ifdef RAW_IOCTL
+	  case IOCTL_RAW_TRACK:
+	    error = verify_area(VERIFY_WRITE, (void *)param,
+	      unit[drive].type->read_size);
+	    if (error)
+	      return error;
+	    copy_to_user((void *)param, raw_buf, unit[drive].type->read_size);
+	    return unit[drive].type->read_size;
+#endif
+	  default:
+	    printk("fd_ioctl: unknown cmd %d for drive %d.",cmd,drive);
+	    return -ENOSYS;
+         }
+	return 0;
+}
+
+/*======================================================================
+  Return unit ID number of given disk
+======================================================================*/
+static unsigned long get_drive_id(int drive)
+{
+	int i;
+	ulong id = 0;
+
+  	drive&=3;
+	/* 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));
+	}
+
+	selected = -1;
+
+        /*
+         * 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("fd: drive 0 didn't identify, setting default %08lx\n",(ulong)fd_def_df0);
+         }
+	/* return the ID value */
+	return (id);
+}
+
+static void fd_probe(int dev)
+{
+	unsigned long code;
+	int type;
+	int drive;
+	int system;
+
+	drive = dev & 3;
+	code = get_drive_id(drive);
+
+	/* get drive type */
+	unit[drive].type = NULL;
+	for (type = 0; type < num_dr_types; type++)
+		if (drive_types[type].code == code)
+			break;
+
+	if (type >= num_dr_types) {
+		printk("fd_probe: unsupported drive type %08lx found\n",
+		       code);
+		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;
+
+
+	system=(dev & 4)>>2;
+	unit[drive].dtype=&data_types[system];
+	unit[drive].sects=data_types[system].sects*unit[drive].type->sect_mult;
+	unit[drive].blocks=unit[drive].type->heads*unit[drive].type->tracks*
+	    unit[drive].sects;
+
+	floppy_sizes[MINOR(dev)] = unit[drive].blocks >> 1;
+
+}
+
+static void probe_drives(void)
+{
+	int drive,found;
+
+	printk("FD: probing units\nfound ");
+	found=0;
+	for(drive=0;drive<FD_MAX_UNITS;drive++) {
+	  fd_probe(drive);
+	  if (unit[drive].type->code != FD_NODRIVE) {
+	    printk("fd%d ",drive);
+	    found=1;
+	  }
+	}
+	printk("%s\n",(found==0)?" no drives":"");
+}
+
+/*
+ * 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;
+  int system;
+
+  drive = inode->i_rdev & 3;
+  old_dev = fd_device[drive];
+
+  if (fd_ref[drive])
+    if (old_dev != inode->i_rdev)
+      return -EBUSY;
+
+  if (unit[drive].type->code == FD_NODRIVE)
+    return -ENODEV;
+
+  fd_ref[drive]++;
+  fd_device[drive] = inode->i_rdev;
+
+  if (old_dev && old_dev != inode->i_rdev)
+    invalidate_buffers(old_dev);
+
+  if (filp && filp->f_mode)
+    check_disk_change(inode->i_rdev);
+
+  if (filp && (filp->f_flags & (O_WRONLY|O_RDWR))) {
+	  int wrprot;
+
+	  fd_select (drive);
+	  wrprot = !(ciaa.pra & DSKPROT);
+	  fd_deselect (drive);
+
+	  if (wrprot)
+		  return -EROFS;
+  }
+
+  system=(inode->i_rdev & 4)>>2;
+  unit[drive].dtype=&data_types[system];
+  unit[drive].sects=data_types[system].sects*unit[drive].type->sect_mult;
+  unit[drive].blocks=unit[drive].type->heads*unit[drive].type->tracks*
+        unit[drive].sects;
+
+printk("fd%d: accessing %s-disk with %s-layout\n",drive,unit[drive].type->name,
+  data_types[system].name);
+
+  return 0;
+}
+
+static void floppy_release(struct inode * inode, struct file * filp)
+{
+  unsigned long flags;
+
+  fsync_dev(inode->i_rdev);
+  invalidate_inodes(inode->i_rdev);
+  invalidate_buffers(inode->i_rdev);
+  save_flags (flags);
+  cli();
+  if ((inode->i_rdev & 3) == selected && writepending) {
+    del_timer (&flush_track_timer);
+    restore_flags (flags);
+    non_int_flush_track (selected);
+  } else
+    restore_flags (flags);
+  
+  if (!fd_ref[inode->i_rdev & 3]--) {
+    printk("floppy_release with fd_ref == 0");
+    fd_ref[inode->i_rdev & 3] = 0;
+  }
+}
+
+void amiga_floppy_setup (char *str, int *ints)
+{
+printk ("amiflop: Setting default df0 to %x\n", ints[1]);
+fd_def_df0 = ints[1];
+}
+
+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 */
+	NULL,			/* fasync */
+	amiga_floppy_change,	/* check_media_change */
+	NULL,			/* revalidate */
+};
+
+static void fd_block_done(int irq, struct pt_regs *fp, void *dummy)
+{
+  if (block_flag)
+    custom.dsklen = 0x4000;
+
+  block_flag = 0;
+  wake_up (&wait_fd_block);
+
+  if (writefromint) {
+    /* 
+     * if it was a write from an interrupt,
+     * we will call post_write from here
+     */
+    writepending = 2;
+    post_write_timer.expires = 1; /* at least 2 ms */
+    add_timer(&post_write_timer);
+  }
+
+}
+
+int amiga_floppy_init(void)
+{
+  int i;
+
+  if (!AMIGAHW_PRESENT(AMI_FLOPPY))
+    return -ENXIO;
+
+  if (register_blkdev(MAJOR_NR,"fd",&floppy_fops)) {
+    printk("Unable to get major %d for floppy\n",MAJOR_NR);
+    return -EBUSY;
+  }
+
+  /* initialize variables */
+  motor_on_timer.next = NULL;
+  motor_on_timer.prev = NULL;
+  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++) {
+	  motor_off_timer[i].next = NULL;
+	  motor_off_timer[i].prev = NULL;
+	  motor_off_timer[i].expires = 0;
+	  motor_off_timer[i].data = i;
+	  motor_off_timer[i].function = fd_motor_off;
+
+	  unit[i].track = -1;
+  }
+
+  flush_track_timer.next = NULL;
+  flush_track_timer.prev = NULL;
+  flush_track_timer.expires = 0;
+  flush_track_timer.data = 0;
+  flush_track_timer.function = flush_track_callback;
+
+  post_write_timer.next = NULL;
+  post_write_timer.prev = NULL;
+  post_write_timer.expires = 0;
+  post_write_timer.data = 0;
+  post_write_timer.function = post_write;
+  
+  blk_dev[MAJOR_NR].request_fn = DEVICE_REQUEST;
+  blksize_size[MAJOR_NR] = floppy_blocksizes;
+  blk_size[MAJOR_NR] = floppy_sizes;
+
+
+  timer_table[FLOPPY_TIMER].fn = NULL;
+  timer_active &= ~(1 << FLOPPY_TIMER);
+
+  if (fd_def_df0==0) {
+    if ((boot_info.bi_amiga.model == AMI_3000) ||
+        (boot_info.bi_amiga.model == AMI_4000))
+      fd_def_df0=FD_HD_3;
+    else
+      fd_def_df0=FD_DD_3;
+  }
+
+  probe_drives();
+
+  raw_buf = (char *)amiga_chip_alloc (RAW_BUF_SIZE);
+
+  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;
+
+  add_isr(IRQ_FLOPPY, fd_block_done, 0, NULL, "floppy_dma");
+  add_isr(IRQ_AMIGA_CIAA_TB, ms_isr, 0, NULL, "floppy_timer");
+
+  return 0;
+}