Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1850 insertions, 0 deletions

diff --git a/drivers/block/amiflop.c b/drivers/block/amiflop.c
new file mode 100644
index 00000000000..1468e8cf712
--- /dev/null
+++ b/drivers/block/amiflop.c
@@ -0,0 +1,1850 @@
+/*
+ *  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/fd.h>
+#include <linux/hdreg.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/amifdreg.h>
+#include <linux/amifd.h>
+#include <linux/buffer_head.h>
+#include <linux/blkdev.h>
+#include <linux/elevator.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 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");
+
+static struct request_queue *floppy_queue;
+#define QUEUE (floppy_queue)
+#define CURRENT elv_next_request(floppy_queue)
+
+/*
+ *  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 = sizeof(drive_types) / sizeof(drive_types[0]);
+
+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_WAIT_QUEUE_HEAD(motor_wait);
+
+static volatile int selected = -1;	/* currently selected drive */
+
+static int writepending;
+static int writefromint;
+static char *raw_buf;
+
+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 volatile int ms_busy = -1;
+static DECLARE_WAIT_QUEUE_HEAD(ms_wait);
+#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
+
+/* 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, struct pt_regs *fp)
+{
+	ms_busy = -1;
+	wake_up(&ms_wait);
+	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)
+{
+	unsigned long flags;
+	int ticks;
+	if (ms > 0) {
+		local_irq_save(flags);
+		while (ms_busy == 0)
+			sleep_on(&ms_wait);
+		ms_busy = 0;
+		local_irq_restore(flags);
+		ticks = MS_TICKS*ms-1;
+		ciaa.tblo=ticks%256;
+		ciaa.tbhi=ticks/256;
+		ciaa.crb=0x19; /*count eclock, force load, one-shoot, start */
+		sleep_on(&ms_wait);
+	}
+}
+
+/* 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\n",drive,fdc_busy,fdc_nested);
+#endif
+	local_irq_save(flags);
+	while (!try_fdc(drive))
+		sleep_on(&fdc_wait);
+	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\n");
+	printk("rel_fdc: fdc_busy %d fdc_nested %d\n",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\n",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\n",drive);
+#endif
+	if (drive != selected) {
+		printk(KERN_WARNING "Deselecting drive %d while %d was selected!\n",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) {
+		wake_up (&motor_wait);
+	} 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);
+
+		motor_on_timer.data = nr;
+		mod_timer(&motor_on_timer, jiffies + HZ/2);
+
+		on_attempts = 10;
+		sleep_on (&motor_wait);
+		fd_deselect(nr);
+	}
+
+	if (on_attempts == 0) {
+		on_attempts = -1;
+#if 0
+		printk (KERN_ERR "motor_on failed, turning motor off\n");
+		fd_motor_off (nr);
+		return 0;
+#else
+		printk (KERN_WARNING "DSKRDY not set after 1.5 seconds - assuming drive is spinning notwithstanding\n");
+#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\n", 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\n",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\n", (ulong)fd_def_df0);
+	}
+	/* return the ID value */
+	return (id);
+}
+
+static irqreturn_t fd_block_done(int irq, void *dummy, struct pt_regs *fp)
+{
+	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);
+	while (block_flag)
+		sleep_on(&wait_fd_block);
+	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;
+
+	while (block_flag)
+		sleep_on (&wait_fd_block);
+
+	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;
+	}
+	while (block_flag)
+		sleep_on(&wait_fd_block);
+	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\n",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\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(KERN_INFO "MFM_HEADER: %08lx,%08lx\n", hdr.hdrchk, csum);
+			return MFM_HEADER;
+		}
+
+		/* verify track */
+		if (hdr.track != unit[drive].track) {
+			printk(KERN_INFO "MFM_TRACK: %d, %d\n", 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\n",
+			       hdr.magic, hdr.track, hdr.sect, hdr.ord, scnt,
+			       hdr.datachk, csum);
+			printk (KERN_INFO "data=(%lx,%lx,%lx,%lx)\n",
+				((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\n", 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\n",
+				       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\n", 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\n",
+			       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\n",
+			       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\n",
+			       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\n", hdr.len_desc);
+			return MFM_DATA;
+		}
+#ifdef DEBUG
+		printk("hdr accepted\n");
+#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\n",
+			       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\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 *)(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\n", hdr.track, hdr.side,
+			       hdr.sec, hdr.len_desc, scnt,data_crc[0], crc);
+			printk(KERN_INFO "data=(%lx,%lx,%lx,%lx,...)\n",
+			       ((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++;
+	}