patch-2.1.122 linux/drivers/scsi/imm.c

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diff -u --recursive --new-file v2.1.121/linux/drivers/scsi/imm.c linux/drivers/scsi/imm.c
@@ -0,0 +1,1321 @@
+/* imm.c   --  low level driver for the IOMEGA MatchMaker
+ * parallel port SCSI host adapter.
+ * 
+ * (The IMM is the embedded controller in the ZIP Plus drive.)
+ * 
+ * Current Maintainer: David Campbell (Perth, Western Australia)
+ *                     campbell@gear.torque.net
+ *                     dcampbel@p01.as17.honeywell.com.au
+ *
+ * My unoffical company acronym list is 21 pages long:
+ *      FLA:    Four letter acronym with built in facility for
+ *              future expansion to five letters.
+ */
+
+#include <linux/config.h>
+
+/* The following #define is to avoid a clash with hosts.c */
+#define IMM_CODE 1
+#define IMM_PROBE_SPP   0x0001
+#define IMM_PROBE_PS2   0x0002
+#define IMM_PROBE_ECR   0x0010
+#define IMM_PROBE_EPP17 0x0100
+#define IMM_PROBE_EPP19 0x0200
+
+void imm_reset_pulse(unsigned int base);
+static int device_check(int host_no);
+
+#include <linux/blk.h>
+#include <asm/io.h>
+#include <linux/parport.h>
+#include "sd.h"
+#include "hosts.h"
+typedef struct {
+    struct pardevice *dev;      /* Parport device entry         */
+    int base;			/* Actual port address          */
+    int mode;			/* Transfer mode                */
+    int host;			/* Host number (for proc)       */
+    Scsi_Cmnd *cur_cmd;		/* Current queued command       */
+    struct tq_struct imm_tq;	/* Polling interupt stuff       */
+    unsigned long jstart;	/* Jiffies at start             */
+    unsigned failed:1;		/* Failure flag                 */
+    unsigned dp:1;		/* Data phase present           */
+    unsigned rd:1;		/* Read data in data phase      */
+    unsigned p_busy:1;		/* Parport sharing busy flag    */
+} imm_struct;
+
+#define IMM_EMPTY \
+{	dev:		NULL,		\
+	base:		-1,		\
+	mode:		IMM_AUTODETECT,	\
+	host:		-1,		\
+	cur_cmd:	NULL,		\
+	imm_tq:		{0, 0, imm_interrupt, NULL},    \
+	jstart:		0,		\
+	failed:		0,		\
+	dp:		0,		\
+	rd:		0,		\
+	p_busy:		0		\
+}
+
+#include "imm.h"
+#define NO_HOSTS 4
+static imm_struct imm_hosts[NO_HOSTS] =
+{IMM_EMPTY, IMM_EMPTY, IMM_EMPTY, IMM_EMPTY};
+
+#define IMM_BASE(x)	imm_hosts[(x)].base
+
+int base[NO_HOSTS] =
+{0x03bc, 0x0378, 0x0278, 0x0000};
+
+void imm_wakeup(void *ref)
+{
+    imm_struct *imm_dev = (imm_struct *) ref;
+
+    if (!imm_dev->p_busy)
+        return;
+
+    if (parport_claim(imm_dev->dev)) {
+        printk("imm: bug in imm_wakeup\n");
+        return;
+    }
+    imm_dev->p_busy = 0;
+    imm_dev->base = imm_dev->dev->port->base;
+    if (imm_dev->cur_cmd)
+        imm_dev->cur_cmd->SCp.phase++;
+    return;
+}
+
+int imm_release(struct Scsi_Host *host)
+{
+    int host_no = host->unique_id;
+
+    printk("Releasing imm%i\n", host_no);
+    parport_unregister_device(imm_hosts[host_no].dev);
+    return 0;
+}
+
+static int imm_pb_claim(int host_no)
+{
+    if (parport_claim(imm_hosts[host_no].dev)) {
+        imm_hosts[host_no].p_busy = 1;
+        return 1;
+    }
+
+    if (imm_hosts[host_no].cur_cmd)
+        imm_hosts[host_no].cur_cmd->SCp.phase++;
+    return 0;
+}
+
+#define imm_pb_release(x) parport_release(imm_hosts[(x)].dev)
+
+/***************************************************************************
+ *                   Parallel port probing routines                        *
+ ***************************************************************************/
+
+#ifndef MODULE
+/*
+ * Command line parameters (for built-in driver):
+ *
+ * Syntax:  imm=base[,mode[,use_sg]]
+ *
+ * For example:  imm=0x378   or   imm=0x378,0,3
+ *
+ */
+
+void imm_setup(char *str, int *ints)
+{
+    static int x = 0;
+
+    if (x == 0) {		/* Disable ALL known ports */
+	int i;
+
+	for (i = 0; i < NO_HOSTS; i++)
+	    parbus_base[i] = 0x0000;
+    }
+    switch (ints[0]) {
+    case 3:
+	imm_sg = ints[3];
+    case 2:
+	imm_hosts[x].mode = ints[2];
+	parbus_base[x] = ints[1];
+	break;
+    default:
+	printk("IMM: I only use between 2 to 3 parameters.\n");
+	break;
+    }
+    x++;
+}
+#else
+Scsi_Host_Template driver_template = IMM;
+#include  "scsi_module.c"
+#endif
+
+int imm_detect(Scsi_Host_Template * host)
+{
+    struct Scsi_Host *hreg;
+    int ports;
+    int i, nhosts, try_again;
+    struct parport *pb = parport_enumerate();
+
+    printk("imm: Version %s\n", IMM_VERSION);
+    nhosts = 0;
+    try_again = 0;
+
+    if (!pb) {
+        printk("imm: parport reports no devices.\n");
+        return 0;
+    }
+
+  retry_entry:
+    for (i = 0; pb; i++, pb = pb->next) {
+        int modes, ppb;
+
+        imm_hosts[i].dev =
+            parport_register_device(pb, "imm", NULL, imm_wakeup,
+                         NULL, PARPORT_DEV_TRAN, (void *) &imm_hosts[i]);
+
+        /* Claim the bus so it remembers what we do to the control
+         * registers. [ CTR and ECP ]
+         */
+        if (imm_pb_claim(i))
+            while (imm_hosts[i].p_busy)
+                schedule();     /* We are safe to schedule here */
+
+        ppb = IMM_BASE(i) = imm_hosts[i].dev->port->base;
+        w_ctr(ppb, 0x0c);
+        modes = imm_hosts[i].dev->port->modes;
+
+        /* Mode detection works up the chain of speed
+         * This avoids a nasty if-then-else-if-... tree
+         */
+        imm_hosts[i].mode = IMM_NIBBLE;
+
+        if (modes & PARPORT_MODE_PCPS2)
+            imm_hosts[i].mode = IMM_PS2;
+
+        if (modes & PARPORT_MODE_PCECPPS2) {
+            w_ecr(ppb, 0x20);
+            imm_hosts[i].mode = IMM_PS2;
+        }
+        if (modes & PARPORT_MODE_PCECPEPP)
+            w_ecr(ppb, 0x80);
+
+        /* Done configuration */
+        imm_pb_release(i);
+
+        if (imm_init(i)) {
+            parport_unregister_device(imm_hosts[i].dev);
+            continue;
+        }
+        /* now the glue ... */
+        switch (imm_hosts[i].mode) {
+        case IMM_NIBBLE:
+            ports = 3;
+            break;
+        case IMM_PS2:
+            ports = 3;
+            break;
+        case IMM_EPP_8:
+        case IMM_EPP_16:
+        case IMM_EPP_32:
+            ports = 8;
+            break;
+        default:                /* Never gets here */
+            continue;
+        }
+
+        host->can_queue = IMM_CAN_QUEUE;
+        host->sg_tablesize = imm_sg;
+        hreg = scsi_register(host, 0);
+        hreg->io_port = pb->base;
+        hreg->n_io_port = ports;
+        hreg->dma_channel = -1;
+        hreg->unique_id = i;
+        imm_hosts[i].host = hreg->host_no;
+        nhosts++;
+    }
+    if (nhosts == 0) {
+        if (try_again == 1)
+            return 0;
+        try_again = 1;
+        goto retry_entry;
+    } else
+        return 1;               /* return number of hosts detected */
+}
+
+/* This is to give the imm driver a way to modify the timings (and other
+ * parameters) by writing to the /proc/scsi/imm/0 file.
+ * Very simple method really... (To simple, no error checking :( )
+ * Reason: Kernel hackers HATE having to unload and reload modules for
+ * testing...
+ * Also gives a method to use a script to obtain optimum timings (TODO)
+ */
+
+static inline int imm_strncmp(const char *a, const char *b, int len)
+{
+    int loop;
+    for (loop = 0; loop < len; loop++)
+	if (a[loop] != b[loop])
+	    return 1;
+
+    return 0;
+}
+
+static inline int imm_proc_write(int hostno, char *buffer, int length)
+{
+    unsigned long x;
+
+    if ((length > 5) && (imm_strncmp(buffer, "mode=", 5) == 0)) {
+	x = simple_strtoul(buffer + 5, NULL, 0);
+	imm_hosts[hostno].mode = x;
+	return length;
+    }
+    printk("imm /proc: invalid variable\n");
+    return (-EINVAL);
+}
+
+int imm_proc_info(char *buffer, char **start, off_t offset,
+		  int length, int hostno, int inout)
+{
+    int i;
+    int len = 0;
+
+    for (i = 0; i < 4; i++)
+	if (imm_hosts[i].host == hostno)
+	    break;
+
+    if (inout)
+	return imm_proc_write(i, buffer, length);
+
+    len += sprintf(buffer + len, "Version : %s\n", IMM_VERSION);
+    len += sprintf(buffer + len, "Parport : %s\n", imm_hosts[i].dev->port->name);
+    len += sprintf(buffer + len, "Mode    : %s\n", IMM_MODE_STRING[imm_hosts[i].mode]);
+
+    /* Request for beyond end of buffer */
+    if (offset > len)
+	return 0;
+
+    *start = buffer + offset;
+    len -= offset;
+    if (len > length)
+	len = length;
+    return len;
+}
+
+#if IMM_DEBUG > 0
+#define imm_fail(x,y) printk("imm: imm_fail(%i) from %s at line %d\n",\
+	   y, __FUNCTION__, __LINE__); imm_fail_func(x,y);
+static inline void imm_fail_func(int host_no, int error_code)
+#else
+static inline void imm_fail(int host_no, int error_code)
+#endif
+{
+    /* If we fail a device then we trash status / message bytes */
+    if (imm_hosts[host_no].cur_cmd) {
+	imm_hosts[host_no].cur_cmd->result = error_code << 16;
+	imm_hosts[host_no].failed = 1;
+    }
+}
+
+/*
+ * Wait for the high bit to be set.
+ * 
+ * In principle, this could be tied to an interrupt, but the adapter
+ * doesn't appear to be designed to support interrupts.  We spin on
+ * the 0x80 ready bit. 
+ */
+static unsigned char imm_wait(int host_no)
+{
+    int k;
+    unsigned short ppb = IMM_BASE(host_no);
+    unsigned char r;
+
+    w_ctr(ppb, 0x0c);
+
+    k = IMM_SPIN_TMO;
+    do {
+	r = r_str(ppb);
+	k--;
+	udelay(1);
+    }
+    while (!(r & 0x80) && (k));
+
+    /*
+     * STR register (LPT base+1) to SCSI mapping:
+     *
+     * STR      imm     imm
+     * ===================================
+     * 0x80     S_REQ   S_REQ
+     * 0x40     !S_BSY  (????)
+     * 0x20     !S_CD   !S_CD
+     * 0x10     !S_IO   !S_IO
+     * 0x08     (????)  !S_BSY
+     *
+     * imm      imm     meaning
+     * ==================================
+     * 0xf0     0xb8    Bit mask
+     * 0xc0     0x88    ZIP wants more data
+     * 0xd0     0x98    ZIP wants to send more data
+     * 0xe0     0xa8    ZIP is expecting SCSI command data
+     * 0xf0     0xb8    end of transfer, ZIP is sending status
+     */
+    w_ctr(ppb, 0x04);
+    if (k)
+	return (r & 0xb8);
+
+    /* Counter expired - Time out occured */
+    imm_fail(host_no, DID_TIME_OUT);
+    printk("imm timeout in imm_wait\n");
+    return 0;			/* command timed out */
+}
+
+static int imm_negotiate(imm_struct * tmp)
+{
+    /*
+     * The following is supposedly the IEEE 1248-1994 negotiate
+     * sequence. I have yet to obtain a copy of the above standard
+     * so this is a bit of a guess...
+     *
+     * A fair chunk of this is based on the Linux parport implementation
+     * of IEEE 1284.
+     *
+     * Return 0 if data available
+     *        1 if no data available
+     */
+
+    unsigned short base = tmp->base;
+    unsigned char a, mode;
+
+    switch (tmp->mode) {
+    case IMM_NIBBLE:
+	mode = 0x00;
+	break;
+    case IMM_PS2:
+	mode = 0x01;
+	break;
+    default:
+	return 0;
+    }
+
+    w_ctr(base, 0x04);
+    udelay(5);
+    w_dtr(base, mode);
+    udelay(100);
+    w_ctr(base, 0x06);
+    udelay(5);
+    a = (r_str(base) & 0x20) ? 0 : 1;
+    udelay(5);
+    w_ctr(base, 0x07);
+    udelay(5);
+    w_ctr(base, 0x06);
+
+    if (a) {
+	printk("IMM: IEEE1284 negotiate indicates no data available.\n");
+	imm_fail(tmp->host, DID_ERROR);
+    }
+    return a;
+}
+
+static inline void epp_reset(unsigned short ppb)
+{
+    int i;
+
+    i = r_str(ppb);
+    w_str(ppb, i);
+    w_str(ppb, i & 0xfe);
+}
+
+static inline void ecp_sync(unsigned short ppb)
+{
+    int i;
+
+    if ((r_ecr(ppb) & 0xe0) != 0x80)
+        return;
+
+    for (i = 0; i < 100; i++) {
+        if (r_ecr(ppb) & 0x01)
+            return;
+        udelay(5);
+    }
+    printk("imm: ECP sync failed as data still present in FIFO.\n");
+}
+
+static inline int imm_byte_out(unsigned short base, const char *buffer, int len)
+{
+    int i;
+
+    w_ctr(base, 0x4);		/* aimmrently a sane mode */
+    for (i = len >> 1; i; i--) {
+	w_dtr(base, *buffer++);
+	w_ctr(base, 0x5);	/* Drop STROBE low */
+	w_dtr(base, *buffer++);
+	w_ctr(base, 0x0);	/* STROBE high + INIT low */
+    }
+    w_ctr(base, 0x4);		/* aimmrently a sane mode */
+    return 1;			/* All went well - we hope! */
+}
+
+static inline int imm_epp_out(unsigned short base, char *buffer, int len)
+{
+    int i;
+    for (i = len; i; i--)
+	w_epp(base, *buffer++);
+    return 1;
+}
+
+static inline int imm_nibble_in(unsigned short base, char *buffer, int len)
+{
+    unsigned char h, l;
+    int i;
+
+    /*
+     * The following is based on documented timing signals
+     */
+    w_ctr(base, 0x4);
+    for (i = len; i; i--) {
+	w_ctr(base, 0x6);
+	l = r_str(base);
+	w_ctr(base, 0x5);
+	h = r_str(base);
+	w_ctr(base, 0x4);
+	*buffer++ = (h & 0xf0) | ((l & 0xf0) >> 4);
+    }
+    return 1;			/* All went well - we hope! */
+}
+
+static inline int imm_byte_in(unsigned short base, char *buffer, int len)
+{
+    int i;
+
+    /*
+     * The following is based on documented timing signals
+     */
+    w_ctr(base, 0x4);
+    for (i = len; i; i--) {
+	w_ctr(base, 0x26);
+	*buffer++ = r_dtr(base);
+	w_ctr(base, 0x25);
+    }
+    return 1;			/* All went well - we hope! */
+}
+
+static inline int imm_epp_in(unsigned short base, char *buffer, int len)
+{
+    int i;
+    for (i = len; i; i--)
+	*buffer++ = r_epp(base);
+    return 1;
+}
+
+static int imm_out(int host_no, char *buffer, int len)
+{
+    int r;
+    unsigned short ppb = IMM_BASE(host_no);
+
+    r = imm_wait(host_no);
+
+    /*
+     * Make sure that:
+     * a) the SCSI bus is BUSY (device still listening)
+     * b) the device is listening
+     */
+    if ((r & 0x18) != 0x08) {
+	imm_fail(host_no, DID_ERROR);
+	printk("IMM: returned SCSI status %2x\n", r);
+	return 0;
+    }
+    switch (imm_hosts[host_no].mode) {
+    case IMM_EPP_32:
+    case IMM_EPP_16:
+    case IMM_EPP_8:
+        epp_reset(ppb);
+        w_ctr(ppb, 0x4);
+	r = imm_epp_out(ppb, buffer, len);
+        w_ctr(ppb, 0xc);
+        ecp_sync(ppb);
+	break;
+
+    case IMM_NIBBLE:
+    case IMM_PS2:
+	/* 8 bit output, with a loop */
+	r = imm_byte_out(ppb, buffer, len);
+	break;
+
+    default:
+	printk("IMM: bug in imm_out()\n");
+	r = 0;
+    }
+    return r;
+}
+
+static int imm_in(int host_no, char *buffer, int len)
+{
+    int r;
+    unsigned short ppb = IMM_BASE(host_no);
+
+    r = imm_wait(host_no);
+
+    /*
+     * Make sure that:
+     * a) the SCSI bus is BUSY (device still listening)
+     * b) the device is sending data
+     */
+    if ((r & 0x18) != 0x18) {
+	imm_fail(host_no, DID_ERROR);
+	return 0;
+    }
+    switch (imm_hosts[host_no].mode) {
+    case IMM_NIBBLE:
+	/* 4 bit input, with a loop */
+	r = imm_nibble_in(ppb, buffer, len);
+	w_ctr(ppb, 0xc);
+	break;
+
+    case IMM_PS2:
+	/* 8 bit input, with a loop */
+	r = imm_byte_in(ppb, buffer, len);
+	w_ctr(ppb, 0xc);
+	break;
+
+    case IMM_EPP_32:
+    case IMM_EPP_16:
+    case IMM_EPP_8:
+        epp_reset(ppb);
+        w_ctr(ppb, 0x24);
+	r = imm_epp_in(ppb, buffer, len);
+        w_ctr(ppb, 0x2c);
+        ecp_sync(ppb);
+	break;
+
+    default:
+	printk("IMM: bug in imm_ins()\n");
+	r = 0;
+	break;
+    }
+    return r;
+}
+
+static int imm_cpp(unsigned short ppb, unsigned char b)
+{
+    /*
+     * Comments on udelay values refer to the
+     * Command Packet Protocol (CPP) timing diagram.
+     */
+
+    unsigned char s1, s2, s3;
+    w_ctr(ppb, 0x0c);
+    udelay(2);			/* 1 usec - infinite */
+    w_dtr(ppb, 0xaa);
+    udelay(10);			/* 7 usec - infinite */
+    w_dtr(ppb, 0x55);
+    udelay(10);			/* 7 usec - infinite */
+    w_dtr(ppb, 0x00);
+    udelay(10);			/* 7 usec - infinite */
+    w_dtr(ppb, 0xff);
+    udelay(10);			/* 7 usec - infinite */
+    s1 = r_str(ppb) & 0xb8;
+    w_dtr(ppb, 0x87);
+    udelay(10);			/* 7 usec - infinite */
+    s2 = r_str(ppb) & 0xb8;
+    w_dtr(ppb, 0x78);
+    udelay(10);			/* 7 usec - infinite */
+    s3 = r_str(ppb) & 0x38;
+    /*
+     * Values for b are:
+     * 0000 00aa    Assign address aa to current device
+     * 0010 00aa    Select device aa in EPP Winbond mode
+     * 0010 10aa    Select device aa in EPP mode
+     * 0011 xxxx    Deselect all devices
+     * 0110 00aa    Test device aa
+     * 1101 00aa    Select device aa in ECP mode
+     * 1110 00aa    Select device aa in Compatible mode
+     */
+    w_dtr(ppb, b);
+    udelay(2);			/* 1 usec - infinite */
+    w_ctr(ppb, 0x0c);
+    udelay(10);			/* 7 usec - infinite */
+    w_ctr(ppb, 0x0d);
+    udelay(2);			/* 1 usec - infinite */
+    w_ctr(ppb, 0x0c);
+    udelay(10);			/* 7 usec - infinite */
+    w_dtr(ppb, 0xff);
+    udelay(10);			/* 7 usec - infinite */
+
+    /*
+     * The following table is electrical pin values.
+     * (BSY is inverted at the CTR register)
+     *
+     *       BSY  ACK  POut SEL  Fault
+     * S1    0    X    1    1    1
+     * S2    1    X    0    1    1
+     * S3    L    X    1    1    S
+     *
+     * L => Last device in chain
+     * S => Selected
+     *
+     * Observered values for S1,S2,S3 are:
+     * Disconnect => f8/58/78
+     * Connect    => f8/58/70
+     */
+    if ((s1 == 0xb8) && (s2 == 0x18) && (s3 == 0x30))
+	return 1;		/* Connected */
+    if ((s1 == 0xb8) && (s2 == 0x18) && (s3 == 0x38))
+	return 0;		/* Disconnected */
+
+    return -1;			/* No device present */
+}
+
+static inline int imm_connect(int host_no, int flag)
+{
+    unsigned short ppb = IMM_BASE(host_no);
+
+    imm_cpp(ppb, 0xe0);		/* Select device 0 in compatible mode */
+    imm_cpp(ppb, 0x30);		/* Disconnect all devices */
+
+    if ((imm_hosts[host_no].mode == IMM_EPP_8) ||
+	(imm_hosts[host_no].mode == IMM_EPP_16) ||
+	(imm_hosts[host_no].mode == IMM_EPP_32))
+	return imm_cpp(ppb, 0x28);	/* Select device 0 in EPP mode */
+    return imm_cpp(ppb, 0xe0);	/* Select device 0 in compatible mode */
+}
+
+static void imm_disconnect(int host_no)
+{
+    unsigned short ppb = IMM_BASE(host_no);
+
+    imm_cpp(ppb, 0x30);		/* Disconnect all devices */
+}
+
+static int imm_select(int host_no, int target)
+{
+    int k;
+    unsigned short ppb = IMM_BASE(host_no);
+
+    /*
+     * Firstly we want to make sure there is nothing
+     * holding onto the SCSI bus.
+     */
+    w_ctr(ppb, 0xc);
+
+    k = IMM_SELECT_TMO;
+    do {
+	k--;
+    } while ((r_str(ppb) & 0x08) && (k));
+
+    if (!k)
+	return 0;
+
+    /*
+     * Now assert the SCSI ID (HOST and TARGET) on the data bus
+     */
+    w_ctr(ppb, 0x4);
+    w_dtr(ppb, 0x80 | (1 << target));
+    udelay(1);
+
+    /*
+     * Deassert SELIN first followed by STROBE
+     */
+    w_ctr(ppb, 0xc);
+    w_ctr(ppb, 0xd);
+
+    /*
+     * ACK should drop low while SELIN is deasserted.
+     * FAULT should drop low when the SCSI device latches the bus.
+     */
+    k = IMM_SELECT_TMO;
+    do {
+	k--;
+    }
+    while (!(r_str(ppb) & 0x08) && (k));
+
+    /*
+     * Place the interface back into a sane state (status mode)
+     */
+    w_ctr(ppb, 0xc);
+    return (k) ? 1 : 0;
+}
+
+static int imm_init(int host_no)
+{
+    int retv;
+
+#if defined(CONFIG_PARPORT) || defined(CONFIG_PARPORT_MODULE)
+    if (imm_pb_claim(host_no))
+        while (imm_hosts[host_no].p_busy)
+            schedule();         /* We can safe schedule here */
+#endif
+    retv = imm_connect(host_no, 0);
+
+    if (retv == 1) {
+	imm_reset_pulse(IMM_BASE(host_no));
+	udelay(1000);		/* Delay to allow devices to settle */
+	imm_disconnect(host_no);
+	udelay(1000);		/* Another delay to allow devices to settle */
+	retv = device_check(host_no);
+	imm_pb_release(host_no);
+	return retv;
+    }
+
+    imm_pb_release(host_no);
+    return 1;
+}
+
+static inline int imm_send_command(Scsi_Cmnd * cmd)
+{
+    int host_no = cmd->host->unique_id;
+    int k;
+
+    /* NOTE: IMM uses byte pairs */
+    for (k = 0; k < cmd->cmd_len; k += 2)
+	if (!imm_out(host_no, &cmd->cmnd[k], 2))
+	    return 0;
+    return 1;
+}
+
+/*
+ * The bulk flag enables some optimisations in the data transfer loops,
+ * it should be true for any command that transfers data in integral
+ * numbers of sectors.
+ * 
+ * The driver appears to remain stable if we speed up the parallel port
+ * i/o in this function, but not elsewhere.
+ */
+static int imm_completion(Scsi_Cmnd * cmd)
+{
+    /* Return codes:
+     * -1     Error
+     *  0     Told to schedule
+     *  1     Finished data transfer
+     */
+    int host_no = cmd->host->unique_id;
+    unsigned short ppb = IMM_BASE(host_no);
+    unsigned long start_jiffies = jiffies;
+
+    unsigned char r, v;
+    int fast, bulk, status;
+
+    v = cmd->cmnd[0];
+    bulk = ((v == READ_6) ||
+	    (v == READ_10) ||
+	    (v == WRITE_6) ||
+	    (v == WRITE_10));
+
+    /*
+     * We only get here if the drive is ready to comunicate,
+     * hence no need for a full imm_wait.
+     */
+    w_ctr(ppb, 0x0c);
+    r = (r_str(ppb) & 0xb8);
+
+    /*
+     * while (device is not ready to send status byte)
+     *     loop;
+     */
+    while (r != (unsigned char) 0xb8) {
+	/*
+	 * If we have been running for more than a full timer tick
+	 * then take a rest.
+	 */
+	if (jiffies > start_jiffies + 1)
+	    return 0;
+
+	/*
+	 * FAIL if:
+	 * a) Drive status is screwy (!ready && !present)
+	 * b) Drive is requesting/sending more data than expected
+	 */
+	if (((r & 0x88) != 0x88) || (cmd->SCp.this_residual <= 0)) {
+	    imm_fail(host_no, DID_ERROR);
+	    return -1;		/* ERROR_RETURN */
+	}
+	/* determine if we should use burst I/O */
+	if (imm_hosts[host_no].rd == 0) {
+	    fast = (bulk && (cmd->SCp.this_residual >= IMM_BURST_SIZE)) ? IMM_BURST_SIZE : 2;
+	    status = imm_out(host_no, cmd->SCp.ptr, fast);
+	} else {
+	    fast = (bulk && (cmd->SCp.this_residual >= IMM_BURST_SIZE)) ? IMM_BURST_SIZE : 1;
+	    status = imm_in(host_no, cmd->SCp.ptr, fast);
+	}
+
+	cmd->SCp.ptr += fast;
+	cmd->SCp.this_residual -= fast;
+
+	if (!status) {
+	    imm_fail(host_no, DID_BUS_BUSY);
+	    return -1;		/* ERROR_RETURN */
+	}
+	if (cmd->SCp.buffer && !cmd->SCp.this_residual) {
+	    /* if scatter/gather, advance to the next segment */
+	    if (cmd->SCp.buffers_residual--) {
+		cmd->SCp.buffer++;
+		cmd->SCp.this_residual = cmd->SCp.buffer->length;
+		cmd->SCp.ptr = cmd->SCp.buffer->address;
+
+		/*
+		 * Make sure that we transfer even number of bytes
+		 * otherwise it makes imm_byte_out() messy.
+		 */
+		if (cmd->SCp.this_residual & 0x01) {
+		    cmd->SCp.this_residual++;
+		    printk("IMM: adjusted buffer for 16 bit transfer\n");
+		}
+	    }
+	}
+	/* Now check to see if the drive is ready to comunicate */
+	w_ctr(ppb, 0x0c);
+	r = (r_str(ppb) & 0xb8);
+
+	/* If not, drop back down to the scheduler and wait a timer tick */
+	if (!(r & 0x80))
+	    return 0;
+    }
+    return 1;			/* FINISH_RETURN */
+}
+
+/* deprecated synchronous interface */
+int imm_command(Scsi_Cmnd * cmd)
+{
+    static int first_pass = 1;
+    int host_no = cmd->host->unique_id;
+
+    if (first_pass) {
+	printk("imm: using non-queuing interface\n");
+	first_pass = 0;
+    }
+    if (imm_hosts[host_no].cur_cmd) {
+	printk("IMM: bug in imm_command\n");
+	return 0;
+    }
+    imm_hosts[host_no].failed = 0;
+    imm_hosts[host_no].jstart = jiffies;
+    imm_hosts[host_no].cur_cmd = cmd;
+    cmd->result = DID_ERROR << 16;	/* default return code */
+    cmd->SCp.phase = 0;
+
+    imm_pb_claim(host_no);
+
+    while (imm_engine(&imm_hosts[host_no], cmd))
+	schedule();
+
+    if (cmd->SCp.phase)		/* Only disconnect if we have connected */
+	imm_disconnect(cmd->host->unique_id);
+
+    imm_pb_release(host_no);
+    imm_hosts[host_no].cur_cmd = 0;
+    return cmd->result;
+}
+
+/*
+ * Since the IMM itself doesn't generate interrupts, we use
+ * the scheduler's task queue to generate a stream of call-backs and
+ * complete the request when the drive is ready.
+ */
+static void imm_interrupt(void *data)
+{
+    imm_struct *tmp = (imm_struct *) data;
+    Scsi_Cmnd *cmd = tmp->cur_cmd;
+
+    if (!cmd) {
+	printk("IMM: bug in imm_interrupt\n");
+	return;
+    }
+    if (imm_engine(tmp, cmd)) {
+	tmp->imm_tq.data = (void *) tmp;
+	tmp->imm_tq.sync = 0;
+	queue_task(&tmp->imm_tq, &tq_timer);
+	return;
+    }
+    /* Command must of completed hence it is safe to let go... */
+#if IMM_DEBUG > 0
+    switch ((cmd->result >> 16) & 0xff) {
+    case DID_OK:
+	break;
+    case DID_NO_CONNECT:
+	printk("imm: no device at SCSI ID %i\n", cmd->target);
+	break;
+    case DID_BUS_BUSY:
+	printk("imm: BUS BUSY - EPP timeout detected\n");
+	break;
+    case DID_TIME_OUT:
+	printk("imm: unknown timeout\n");
+	break;
+    case DID_ABORT:
+	printk("imm: told to abort\n");
+	break;
+    case DID_PARITY:
+	printk("imm: parity error (???)\n");
+	break;
+    case DID_ERROR:
+	printk("imm: internal driver error\n");
+	break;
+    case DID_RESET:
+	printk("imm: told to reset device\n");
+	break;
+    case DID_BAD_INTR:
+	printk("imm: bad interrupt (???)\n");
+	break;
+    default:
+	printk("imm: bad return code (%02x)\n", (cmd->result >> 16) & 0xff);
+    }
+#endif
+
+    if (cmd->SCp.phase > 1)
+	imm_disconnect(cmd->host->unique_id);
+    if (cmd->SCp.phase > 0)
+	imm_pb_release(cmd->host->unique_id);
+
+    tmp->cur_cmd = 0;
+    cmd->scsi_done(cmd);
+    return;
+}
+
+static int imm_engine(imm_struct * tmp, Scsi_Cmnd * cmd)
+{
+    int host_no = cmd->host->unique_id;
+    unsigned short ppb = IMM_BASE(host_no);
+    unsigned char l = 0, h = 0;
+    int retv, x;
+
+    /* First check for any errors that may of occured
+     * Here we check for internal errors
+     */
+    if (tmp->failed)
+	return 0;
+
+    switch (cmd->SCp.phase) {
+    case 0:			/* Phase 0 - Waiting for parport */
+	if ((jiffies - tmp->jstart) > HZ) {
+	    /*
+	     * We waited more than a second
+	     * for parport to call us
+	     */
+	    imm_fail(host_no, DID_BUS_BUSY);
+	    return 0;
+	}
+	return 1;		/* wait until imm_wakeup claims parport */
+	/* Phase 1 - Connected */
+    case 1:
+	imm_connect(host_no, CONNECT_EPP_MAYBE);
+	cmd->SCp.phase++;
+
+	/* Phase 2 - We are now talking to the scsi bus */
+    case 2:
+	if (!imm_select(host_no, cmd->target)) {
+	    imm_fail(host_no, DID_NO_CONNECT);
+	    return 0;
+	}
+	cmd->SCp.phase++;
+
+	/* Phase 3 - Ready to accept a command */
+    case 3:
+	w_ctr(ppb, 0x0c);
+	if (!(r_str(ppb) & 0x80))
+	    return 1;
+
+	if (!imm_send_command(cmd))
+	    return 0;
+	cmd->SCp.phase++;
+
+	/* Phase 4 - Setup scatter/gather buffers */
+    case 4:
+	if (cmd->use_sg) {
+	    /* if many buffers are available, start filling the first */
+	    cmd->SCp.buffer = (struct scatterlist *) cmd->request_buffer;
+	    cmd->SCp.this_residual = cmd->SCp.buffer->length;
+	    cmd->SCp.ptr = cmd->SCp.buffer->address;
+	} else {
+	    /* else fill the only available buffer */
+	    cmd->SCp.buffer = NULL;
+	    cmd->SCp.this_residual = cmd->request_bufflen;
+	    cmd->SCp.ptr = cmd->request_buffer;
+	}
+	cmd->SCp.buffers_residual = cmd->use_sg;
+	cmd->SCp.phase++;
+	if (cmd->SCp.this_residual & 0x01) {
+	    cmd->SCp.this_residual++;
+	    printk("IMM: adjusted buffer for 16 bit transfer\n");
+	}
+	/* Phase 5 - Pre-Data transfer stage */
+    case 5:
+	/* Spin lock for BUSY */
+	w_ctr(ppb, 0x0c);
+	if (!(r_str(ppb) & 0x80))
+	    return 1;
+
+	/* Require negotiation for read requests */
+	x = (r_str(ppb) & 0xb8);
+	tmp->rd = (x & 0x10) ? 1 : 0;
+	tmp->dp = (x & 0x20) ? 0 : 1;
+
+	if ((tmp->dp) && (tmp->rd))
+	    if (imm_negotiate(tmp))
+		return 0;
+	cmd->SCp.phase++;
+
+	/* Phase 6 - Data transfer stage */
+    case 6:
+	/* Spin lock for BUSY */
+	w_ctr(ppb, 0x0c);
+	if (!(r_str(ppb) & 0x80))
+	    return 1;
+
+	if (tmp->dp) {
+	    retv = imm_completion(cmd);
+	    if (retv == -1)
+		return 0;
+	    if (retv == 0)
+		return 1;
+	}
+	cmd->SCp.phase++;
+
+	/* Phase 7 - Post data transfer stage */
+    case 7:
+	if ((tmp->dp) && (tmp->rd)) {
+	    if ((tmp->mode == IMM_NIBBLE) || (tmp->mode == IMM_PS2)) {
+		w_ctr(ppb, 0x4);
+		w_ctr(ppb, 0xc);
+		w_ctr(ppb, 0xe);
+		w_ctr(ppb, 0x4);
+	    }
+	}
+	cmd->SCp.phase++;
+
+	/* Phase 8 - Read status/message */
+    case 8:
+	/* Check for data overrun */
+	if (imm_wait(host_no) != (unsigned char) 0xb8) {
+	    imm_fail(host_no, DID_ERROR);
+	    return 0;
+	}
+	if (imm_negotiate(tmp))
+	    return 0;
+	if (imm_in(host_no, &l, 1)) {	/* read status byte */
+	    /* Check for optional message byte */
+	    if (imm_wait(host_no) == (unsigned char) 0xb8)
+		imm_in(host_no, &h, 1);
+	    cmd->result = (DID_OK << 16) + (l & STATUS_MASK);
+	}
+	if ((tmp->mode == IMM_NIBBLE) || (tmp->mode == IMM_PS2)) {
+	    w_ctr(ppb, 0x4);
+	    w_ctr(ppb, 0xc);
+	    w_ctr(ppb, 0xe);
+	    w_ctr(ppb, 0x4);
+	}
+	return 0;		/* Finished */
+	break;
+
+    default:
+	printk("imm: Invalid scsi phase\n");
+    }
+    return 0;
+}
+
+int imm_queuecommand(Scsi_Cmnd * cmd, void (*done) (Scsi_Cmnd *))
+{
+    int host_no = cmd->host->unique_id;
+
+    if (imm_hosts[host_no].cur_cmd) {
+	printk("IMM: bug in imm_queuecommand\n");
+	return 0;
+    }
+    imm_hosts[host_no].failed = 0;
+    imm_hosts[host_no].jstart = jiffies;
+    imm_hosts[host_no].cur_cmd = cmd;
+    cmd->scsi_done = done;
+    cmd->result = DID_ERROR << 16;	/* default return code */
+    cmd->SCp.phase = 0;		/* bus free */
+
+    imm_pb_claim(host_no);
+
+    imm_hosts[host_no].imm_tq.data = imm_hosts + host_no;
+    imm_hosts[host_no].imm_tq.sync = 0;
+    queue_task(&imm_hosts[host_no].imm_tq, &tq_immediate);
+    mark_bh(IMMEDIATE_BH);
+
+    return 0;
+}
+
+/*
+ * Aimmrently the the disk->capacity attribute is off by 1 sector 
+ * for all disk drives.  We add the one here, but it should really
+ * be done in sd.c.  Even if it gets fixed there, this will still
+ * work.
+ */
+int imm_biosparam(Disk * disk, kdev_t dev, int ip[])
+{
+    ip[0] = 0x40;
+    ip[1] = 0x20;
+    ip[2] = (disk->capacity + 1) / (ip[0] * ip[1]);
+    if (ip[2] > 1024) {
+	ip[0] = 0xff;
+	ip[1] = 0x3f;
+	ip[2] = (disk->capacity + 1) / (ip[0] * ip[1]);
+	if (ip[2] > 1023)
+	    ip[2] = 1023;
+    }
+    return 0;
+}
+
+int imm_abort(Scsi_Cmnd * cmd)
+{
+    /*
+     * There is no method for aborting commands since Iomega
+     * have tied the SCSI_MESSAGE line high in the interface
+     */
+
+    switch (cmd->SCp.phase) {
+    case 0:			/* Do not have access to parport */
+    case 1:			/* Have not connected to interface */
+	cmd->result = DID_ABORT;
+	cmd->done(cmd);
+	return SCSI_ABORT_SUCCESS;
+	break;
+    default:			/* SCSI command sent, can not abort */
+	return SCSI_ABORT_BUSY;
+	break;
+    }
+}
+
+void imm_reset_pulse(unsigned int base)
+{
+    w_ctr(base, 0x04);
+    w_dtr(base, 0x40);
+    udelay(1);
+    w_ctr(base, 0x0c);
+    w_ctr(base, 0x0d);
+    udelay(50);
+    w_ctr(base, 0x0c);
+    w_ctr(base, 0x04);
+}
+
+int imm_reset(Scsi_Cmnd * cmd, unsigned int x)
+{
+    int host_no = cmd->host->unique_id;
+
+    /*
+     * PHASE1:
+     * Bring the interface crashing down on whatever is running
+     * hopefully this will kill the request.
+     * Bring back up the interface, reset the drive (and anything
+     * attached for that manner)
+     */
+    if (cmd)
+	if (cmd->SCp.phase)
+	    imm_disconnect(cmd->host->unique_id);
+
+    imm_connect(host_no, CONNECT_NORMAL);
+    imm_reset_pulse(IMM_BASE(host_no));
+    udelay(1000);		/* delay for devices to settle down */
+    imm_disconnect(host_no);
+    udelay(1000);		/* Additional delay to allow devices to settle down */
+
+    /*
+     * PHASE2:
+     * Sanity check for the sake of mid-level driver
+     */
+    if (!cmd) {
+	printk("imm bus reset called for invalid command.\n");
+	return SCSI_RESET_NOT_RUNNING;
+    }
+    /*
+     * PHASE3:
+     * Flag the current command as having died due to reset
+     */
+    imm_connect(host_no, CONNECT_NORMAL);
+    imm_fail(host_no, DID_RESET);
+
+    /* Since the command was already on the timer queue imm_interrupt
+     * will be called shortly.
+     */
+    return SCSI_RESET_PENDING;
+}
+
+static int device_check(int host_no)
+{
+    /* This routine looks for a device and then attempts to use EPP
+       to send a command. If all goes as planned then EPP is available. */
+
+    static char cmd[6] =
+    {0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
+    int loop, old_mode, status, k, ppb = IMM_BASE(host_no);
+    unsigned char l;
+
+    old_mode = imm_hosts[host_no].mode;
+    for (loop = 0; loop < 8; loop++) {
+        /* Attempt to use EPP for Test Unit Ready */
+        if ((ppb & 0x0007) == 0x0000)
+            imm_hosts[host_no].mode = IMM_EPP_32;
+
+      second_pass:
+        imm_connect(host_no, CONNECT_EPP_MAYBE);
+        /* Select SCSI device */
+        if (!imm_select(host_no, loop)) {
+            imm_disconnect(host_no);
+            continue;
+        }
+        printk("imm: Found device at ID %i, Attempting to use %s\n", loop,
+               IMM_MODE_STRING[imm_hosts[host_no].mode]);
+
+        /* Send SCSI command */
+        status = 1;
+        w_ctr(ppb, 0x0c);
+        for (l = 0; (l < 3) && (status); l++)
+            status = imm_out(host_no, &cmd[l<<1], 2);
+
+        if (!status) {
+            imm_disconnect(host_no);
+            imm_connect(host_no, CONNECT_EPP_MAYBE);
+            w_dtr(ppb, 0x40);
+            w_ctr(ppb, 0x08);
+            udelay(30);
+            w_ctr(ppb, 0x0c);
+            udelay(1000);
+            imm_disconnect(host_no);
+            udelay(1000);
+            if (imm_hosts[host_no].mode == IMM_EPP_32) {
+                imm_hosts[host_no].mode = old_mode;
+                goto second_pass;
+            }
+            printk("imm: Unable to establish communication, aborting driver load.\n");
+            return 1;
+        }
+        w_ctr(ppb, 0x0c);
+
+        k = 1000000;            /* 1 Second */
+        do {
+            l = r_str(ppb);
+            k--;
+            udelay(1);
+        } while (!(l & 0x80) && (k));
+
+        l &= 0xb8;
+
+        if (l != 0xb8) {
+            imm_disconnect(host_no);
+            imm_connect(host_no, CONNECT_EPP_MAYBE);
+	    imm_reset_pulse(IMM_BASE(host_no));
+            udelay(1000);
+            imm_disconnect(host_no);
+            udelay(1000);
+            if (imm_hosts[host_no].mode == IMM_EPP_32) {
+                imm_hosts[host_no].mode = old_mode;
+                goto second_pass;
+            }
+            printk("imm: Unable to establish communication, aborting driver load.\n");
+            return 1;
+        }
+        imm_disconnect(host_no);
+        printk("imm: Communication established with ID %i using %s\n", loop,
+               IMM_MODE_STRING[imm_hosts[host_no].mode]);
+        imm_connect(host_no, CONNECT_EPP_MAYBE);
+	imm_reset_pulse(IMM_BASE(host_no));
+        udelay(1000);
+        imm_disconnect(host_no);
+        udelay(1000);
+        return 0;
+    }
+    printk("imm: No devices found, aborting driver load.\n");
+    return 1;
+}
+

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TCL-scripts by Sam Shen, slshen@lbl.gov