patch-1.3.4 linux/drivers/scsi/aic7xxx.c

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diff -u --recursive --new-file v1.3.3/linux/drivers/scsi/aic7xxx.c linux/drivers/scsi/aic7xxx.c
@@ -0,0 +1,1715 @@
+/*
+ *  @(#)aic7xxx.c 1.34 94/11/30 jda
+ *
+ *  Adaptec 274x/284x/294x device driver for Linux.
+ *  Copyright (c) 1994 The University of Calgary Department of Computer Science.
+ *  
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *  
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *  
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ *  Sources include the Adaptec 1740 driver (aha1740.c), the
+ *  Ultrastor 24F driver (ultrastor.c), various Linux kernel
+ *  source, the Adaptec EISA config file (!adp7771.cfg), the
+ *  Adaptec AHA-2740A Series User's Guide, the Linux Kernel
+ *  Hacker's Guide, Writing a SCSI Device Driver for Linux,
+ *  the Adaptec 1542 driver (aha1542.c), the Adaptec EISA
+ *  overlay file (adp7770.ovl), the Adaptec AHA-2740 Series
+ *  Technical Reference Manual, the Adaptec AIC-7770 Data
+ *  Book, the ANSI SCSI specification, the ANSI SCSI-2
+ *  specification (draft 10c), ...
+ *
+ *  On a twin-bus adapter card, channel B is ignored.  Rationale:
+ *  it would greatly complicate the sequencer and host driver code,
+ *  and both busses are multiplexed on to the EISA bus anyway.  So
+ *  I don't really see any technical advantage to supporting both.
+ *
+ *  As well, multiple adapter card using the same IRQ level are
+ *  not supported.  It doesn't make sense to configure the cards
+ *  this way from a performance standpoint.  Not to mention that
+ *  the kernel would have to support two devices per registered IRQ.
+ */
+
+#include <stdarg.h>
+#include <asm/io.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/ioport.h>
+#include <linux/bios32.h>
+#include <linux/delay.h>
+#include <linux/pci.h>
+
+#include "../block/blk.h"
+#include "sd.h"
+#include "scsi.h"
+#include "hosts.h"
+#include "aic7xxx.h"
+
+/*
+ *  There should be a specific return value for this in scsi.h, but
+ *  it seems that most drivers ignore it.
+ */
+#define DID_UNDERFLOW	DID_ERROR
+
+/* EISA/VL-bus stuff */
+
+#define MINSLOT		1
+#define MAXSLOT		15
+#define SLOTBASE(x)	((x) << 12)
+
+#define MAXIRQ		15
+
+/* AIC-7770 offset definitions */
+
+#define O_MINREG(x)	((x) + 0xc00)		/* i/o range to reserve */
+#define O_MAXREG(x)	((x) + 0xcbf)
+
+#define O_SCSISEQ(x)	((x) + 0xc00)		/* scsi sequence control */
+#define O_SCSISIGI(x)	((x) + 0xc03)		/* scsi control signal read */
+#define O_SCSISIGO(x)	((x) + 0xc03)		/* scsi control signal write */
+#define O_SCSIID(x)	((x) + 0xc05)		/* scsi id */
+#define O_SSTAT0(x)	((x) + 0xc0b)		/* scsi status register 0 */
+#define O_CLRSINT1(x)	((x) + 0xc0c)		/* clear scsi interrupt 1 */
+#define O_SSTAT1(x)	((x) + 0xc0c)		/* scsi status register 1 */
+#define O_SELID(x)	((x) + 0xc19)		/* [re]selection id */
+#define O_SBLKCTL(x)	((x) + 0xc1f)		/* scsi block control */
+#define O_SEQCTL(x)	((x) + 0xc60)		/* sequencer control */
+#define O_SEQRAM(x)	((x) + 0xc61)		/* sequencer ram data */
+#define O_SEQADDR(x)	((x) + 0xc62)		/* sequencer address (W) */
+#define O_BIDx(x)	((x) + 0xc80)		/* board id */
+#define O_BCTL(x)	((x) + 0xc84)		/* board control */
+#define O_HCNTRL(x)	((x) + 0xc87)		/* host control */
+#define O_SCBPTR(x)	((x) + 0xc90)		/* scb pointer */
+#define O_INTSTAT(x)	((x) + 0xc91)		/* interrupt status */
+#define O_ERROR(x)	((x) + 0xc92)		/* hard error */
+#define O_CLRINT(x)	((x) + 0xc92)		/* clear interrupt status */
+#define O_SCBCNT(x)	((x) + 0xc9a)		/* scb auto increment */
+#define O_QINFIFO(x)	((x) + 0xc9b)		/* queue in fifo */
+#define O_QINCNT(x)	((x) + 0xc9c)		/* queue in count */
+#define O_QOUTFIFO(x)	((x) + 0xc9d)		/* queue out fifo */
+#define O_QOUTCNT(x)	((x) + 0xc9e)		/* queue out count */
+#define O_SCBARRAY(x)	((x) + 0xca0)		/* scb array start */
+
+/* AIC-7870-only definitions */
+
+#define O_DSPCISTATUS(x) ((x) + 0xc86)		/* ??? */
+
+/* host adapter offset definitions */
+
+#define HA_REJBYTE(x)	((x) + 0xc31)		/* 1st message in byte */
+#define HA_MSG_FLAGS(x)	((x) + 0xc35)		/* outgoing message flag */
+#define HA_MSG_LEN(x)	((x) + 0xc36)		/* outgoing message length */
+#define HA_MSG_START(x)	((x) + 0xc37)		/* outgoing message body */
+#define HA_ARG_1(x)	((x) + 0xc4c)		/* sdtr <-> rate parameters */
+#define HA_ARG_2(x)	((x) + 0xc4d)
+#define HA_RETURN_1(x)	((x) + 0xc4c)
+#define HA_RETURN_2(x)	((x) + 0xc4d)
+#define HA_SIGSTATE(x)	((x) + 0xc4e)		/* value in SCSISIGO */
+#define HA_NEEDSDTR(x)	((x) + 0xc4f)		/* synchronous negotiation? */
+#define HA_SCBCOUNT(x)	((x) + 0xc56)		/* number of hardware SCBs */
+
+#define HA_SCSICONF(x)	((x) + 0xc5a)		/* SCSI config register */
+#define HA_INTDEF(x)	((x) + 0xc5c)		/* interrupt def'n register */
+#define HA_HOSTCONF(x)	((x) + 0xc5d)		/* host config def'n register */
+
+/* debugging code */
+
+/*
+#define AIC7XXX_DEBUG
+*/
+
+/*
+ *  If a parity error occurs during a data transfer phase, run the
+ *  command to completion - it's easier that way - making a note
+ *  of the error condition in this location.  This then will modify
+ *  a DID_OK status into a DID_PARITY one for the higher-level SCSI
+ *  code.
+ */
+#define aic7xxx_parity(cmd)	((cmd)->SCp.Status)
+
+/*
+ *  Since the sequencer code DMAs the scatter-gather structures
+ *  directly from memory, we use this macro to assert that the
+ *  kernel structure hasn't changed.
+ */
+#define SG_STRUCT_CHECK(sg) \
+	((char *)&(sg).address - (char *)&(sg) != 0 ||	\
+	 (char *)&(sg).length  - (char *)&(sg) != 8 ||	\
+	 sizeof((sg).address) != 4 ||			\
+	 sizeof((sg).length)  != 4 ||			\
+	 sizeof(sg)	      != 12)
+
+/*
+ *  "Static" structures.  Note that these are NOT initialized
+ *  to zero inside the kernel - we have to initialize them all
+ *  explicitly.
+ *
+ *  We support a maximum of one adapter card per IRQ level (see the
+ *  rationale for this above).  On an interrupt, use the IRQ as an
+ *  index into aic7xxx_boards[] to locate the card information.
+ */
+static struct Scsi_Host *aic7xxx_boards[MAXIRQ + 1];
+
+/*
+ *  The maximum number of SCBs we could have for ANY type
+ *  of card.  DON'T FORGET TO CHANGE THE SCB MASK IN THE
+ *  SEQUENCER CODE IF THIS IS MODIFIED!
+ */
+#define AIC7XXX_MAXSCB	16
+
+struct aic7xxx_host {
+	int base;					/* card base address */
+	int maxscb;					/* hardware SCBs */
+	int startup;					/* intr type check */
+	int extended;					/* extended xlate? */
+	volatile int unpause;				/* value for HCNTRL */
+	volatile Scsi_Cmnd *SCB_array[AIC7XXX_MAXSCB];	/* active commands */
+};
+
+struct aic7xxx_host_config {
+	int irq;					/* IRQ number */
+	int base;					/* I/O base */
+	int maxscb;					/* hardware SCBs */
+	int unpause;					/* value for HCNTRL */
+	int scsi_id;					/* host SCSI id */
+	int extended;					/* extended xlate? */
+};
+
+struct aic7xxx_scb {
+	unsigned char control;
+	unsigned char target_channel_lun;		/* 4/1/3 bits */
+	unsigned char SG_segment_count;
+	unsigned char SG_list_pointer[4];
+	unsigned char SCSI_cmd_pointer[4];
+	unsigned char SCSI_cmd_length;
+	unsigned char RESERVED[2];			/* must be zero */
+	unsigned char target_status;
+	unsigned char residual_data_count[3];
+	unsigned char residual_SG_segment_count;
+	unsigned char data_pointer[4];
+	unsigned char data_count[3];
+#if 0
+	/*
+	 *  No real point in transferring this to the
+	 *  SCB registers.
+	 */
+	unsigned char RESERVED[6];
+#endif
+};
+
+/*
+ *  NB.  This table MUST be ordered shortest period first.
+ */
+static struct {
+	short period;
+	short rate;
+	char *english;
+} aic7xxx_synctab[] = {
+	100,	0,	"10.0",
+	125,	1,	"8.0",
+	150,	2,	"6.67",
+	175,	3,	"5.7",
+	200,	4,	"5.0",
+	225,	5,	"4.4",
+	250,	6,	"4.0",
+	275,	7,	"3.6"
+};
+
+static int aic7xxx_synctab_max =
+	sizeof(aic7xxx_synctab) / sizeof(aic7xxx_synctab[0]);
+
+enum aha_type {
+	T_NONE,
+	T_274X,
+	T_284X,
+	T_294X,
+	T_MAX
+};
+
+#ifdef AIC7XXX_DEBUG
+
+	extern int vsprintf(char *, const char *, va_list);
+
+	static
+	void debug(const char *fmt, ...)
+	{
+		va_list ap;
+		char buf[256];
+
+		va_start(ap, fmt);
+		  vsprintf(buf, fmt, ap);
+		  printk(buf);
+		va_end(ap);
+	}
+
+	static
+	void debug_config(enum aha_type type, struct aic7xxx_host_config *p)
+	{
+		int ioport2, ioport3;
+
+		static char *BRT[T_MAX][16] = {
+			{ },					/* T_NONE */
+			{
+				"2",   "???", "???", "12",	/* T_274X */
+				"???", "???", "???", "28",
+				"???", "???", "???", "44",
+				"???", "???", "???", "60"
+			},
+			{
+				"2",  "4",  "8",  "12",		/* T_284X */
+				"16", "20", "24", "28",
+				"32", "36", "40", "44",
+				"48", "52", "56", "60"
+			},
+			{
+				"???", "???", "???", "???",	/* T_294X */
+				"???", "???", "???", "???",
+				"???", "???", "???", "???",
+				"???", "???", "???", "???"
+			}
+		};
+		static int DFT[4] = {
+			0, 50, 75, 100
+		};
+		static int SST[4] = {
+			256, 128, 64, 32
+		};
+
+		ioport2 = inb(HA_HOSTCONF(p->base));
+		ioport3 = inb(HA_SCSICONF(p->base));
+
+		switch (type) {
+		    case T_274X:
+			printk("AHA274X AT EISA SLOT %d:\n", p->base >> 12);
+			break;
+		    case T_284X:
+			printk("AHA284X AT SLOT %d:\n", p->base >> 12);
+			break;
+		    case T_294X:
+			printk("AHA294X (PCI-bus):\n");
+			break;
+		    default:
+			panic("aic7xxx debug_config: internal error\n");
+		}
+
+		printk("    irq %d\n"
+		       "    bus release time %s bclks\n"
+		       "    data fifo threshold %d%%\n",
+		       p->irq,
+		       BRT[type][(ioport2 >> 2) & 0xf],
+		       DFT[(ioport2 >> 6) & 0x3]);
+
+		printk("    SCSI CHANNEL A:\n"
+		       "        scsi id %d\n"
+		       "        scsi bus parity check %sabled\n"
+		       "        scsi selection timeout %d ms\n"
+		       "        scsi bus reset at power-on %sabled\n",
+		       ioport3 & 0x7,
+		       (ioport3 & 0x20) ? "en" : "dis",
+		       SST[(ioport3 >> 3) & 0x3],
+		       (ioport3 & 0x40) ? "en" : "dis");
+
+		if (type == T_274X) {
+			printk("        scsi bus termination %sabled\n",
+			       (ioport3 & 0x80) ? "en" : "dis");
+		}
+	}
+
+	static
+	void debug_rate(int base, int rate)
+	{
+		int target = inb(O_SCSIID(base)) >> 4;
+
+		if (rate) {
+			printk("aic7xxx: target %d now synchronous at %sMb/s\n",
+			       target,
+			       aic7xxx_synctab[(rate >> 4) & 0x7].english);
+		} else {
+			printk("aic7xxx: target %d using asynchronous mode\n",
+			       target);
+		}
+	}
+
+#else
+
+#	define debug(fmt, args...)
+#	define debug_config(x)
+#	define debug_rate(x,y)
+
+#endif AIC7XXX_DEBUG
+
+/*
+ *  XXX - these options apply unilaterally to _all_ 274x/284x/294x
+ *	  cards in the system.  This should be fixed, but then,
+ *	  does anyone really have more than one in a machine?
+ */
+static int aic7xxx_extended = 0;		/* extended translation on? */
+
+void aic7xxx_setup(char *s, int *dummy)
+{
+	int i;
+	char *p;
+
+	static struct {
+		char *name;
+		int *flag;
+	} options[] = {
+		"extended",	&aic7xxx_extended,
+		NULL
+	};
+
+	for (p = strtok(s, ","); p; p = strtok(NULL, ",")) {
+		for (i = 0; options[i].name; i++)
+			if (!strcmp(options[i].name, p))
+				*(options[i].flag) = !0;
+	}
+}
+
+static
+void aic7xxx_getscb(int base, struct aic7xxx_scb *scb)
+{
+	/*
+	 *  This is almost identical to aic7xxx_putscb().
+	 */
+	outb(0x80, O_SCBCNT(base));	/* SCBAUTO */
+
+	asm volatile("cld\n\t"
+		     "rep\n\t"
+		     "insb"
+		     : /* no output */
+		     :"D" (scb), "c" (sizeof(*scb)), "d" (O_SCBARRAY(base))
+		     :"di", "cx", "dx");
+
+	outb(0, O_SCBCNT(base));
+}
+
+/*
+ *  How much data should be transferred for this SCSI command?  Stop
+ *  at segment sg_last if it's a scatter-gather command so we can
+ *  compute underflow easily.
+ */
+static
+unsigned aic7xxx_length(Scsi_Cmnd *cmd, int sg_last)
+{
+	int i, segments;
+	unsigned length;
+	struct scatterlist *sg;
+
+	segments = cmd->use_sg - sg_last;
+	sg = (struct scatterlist *)cmd->buffer;
+
+	if (cmd->use_sg) {
+		for (i = length = 0;
+		     i < cmd->use_sg && i < segments;
+		     i++)
+		{
+			length += sg[i].length;
+		}
+	} else
+		length = cmd->request_bufflen;
+
+	return(length);
+}
+
+static
+void aic7xxx_sg_check(Scsi_Cmnd *cmd)
+{
+	int i;
+	struct scatterlist *sg = (struct scatterlist *)cmd->buffer;
+
+	if (cmd->use_sg) {
+		for (i = 0; i < cmd->use_sg; i++)
+			if ((unsigned)sg[i].length > 0xffff)
+				panic("aic7xxx_sg_check: s/g segment > 64k\n");
+	}
+}
+
+static
+void aic7xxx_to_scsirate(unsigned char *rate,
+			 unsigned char transfer,
+			 unsigned char offset)
+{
+	int i;
+
+	transfer *= 4;
+
+	for (i = 0; i < aic7xxx_synctab_max-1; i++) {
+
+		if (transfer == aic7xxx_synctab[i].period) {
+			*rate = (aic7xxx_synctab[i].rate << 4) | (offset & 0xf);
+			return;
+		}
+
+		if (transfer > aic7xxx_synctab[i].period &&
+		    transfer < aic7xxx_synctab[i+1].period)
+		{
+			*rate = (aic7xxx_synctab[i+1].rate << 4) |
+				(offset & 0xf);
+			return;
+		}
+	}
+	*rate = 0;
+}
+
+/*
+ *  Pause the sequencer and wait for it to actually stop - this
+ *  is important since the sequencer can disable pausing for critical
+ *  sections.
+ */
+#define PAUSE_SEQUENCER(p)	\
+	do {								\
+		outb(0xe, O_HCNTRL(p->base));	/* IRQMS|PAUSE|INTEN */	\
+									\
+		while ((inb(O_HCNTRL(p->base)) & 0x4) == 0)		\
+			;						\
+	} while (0)
+
+/*
+ *  Unpause the sequencer.  Unremarkable, yet done often enough to
+ *  warrant an easy way to do it.
+ */
+#define UNPAUSE_SEQUENCER(p)	\
+	outb(p->unpause, O_HCNTRL(p->base))	/* IRQMS|INTEN */
+
+/*
+ *  See comments in aic7xxx_loadram() wrt this.
+ */
+#define RESTART_SEQUENCER(p)	\
+	do {							\
+		do {						\
+			outb(0x2, O_SEQCTL(p->base));		\
+								\
+		} while (inb(O_SEQADDR(p->base)) != 0 &&	\
+			 inb(O_SEQADDR(p->base) + 1) != 0);	\
+								\
+		UNPAUSE_SEQUENCER(p);				\
+	} while (0)
+
+/*
+ *  Since we declared this using SA_INTERRUPT, interrupts should
+ *  be disabled all through this function unless we say otherwise.
+ */
+static
+void aic7xxx_isr(int irq)
+{
+	int base, intstat;
+	struct aic7xxx_host *p;
+	
+	p = (struct aic7xxx_host *)aic7xxx_boards[irq]->hostdata;
+	base = p->base;
+
+	/*
+	 *  Check the startup flag - if no commands have been queued,
+	 *  we probably have the interrupt type set wrong.  Reverse
+	 *  the stored value and the active one in the host control
+	 *  register.
+	 */
+	if (p->startup) {
+		p->unpause ^= 0x8;
+		outb(inb(O_HCNTRL(p->base)) ^ 0x8, O_HCNTRL(p->base));
+		return;
+	}
+
+	/*
+	 *  Handle all the interrupt sources - especially for SCSI
+	 *  interrupts, we won't get a second chance at them.
+	 */
+	intstat = inb(O_INTSTAT(base));
+
+	if (intstat & 0x8) {				/* BRKADRINT */
+
+		panic("aic7xxx_isr: brkadrint, error = 0x%x, seqaddr = 0x%x\n",
+		      inb(O_ERROR(base)), inw(O_SEQADDR(base)));
+	}
+
+	if (intstat & 0x4) {				/* SCSIINT */
+
+		int scbptr = inb(O_SCBPTR(base));
+		int status = inb(O_SSTAT1(base));
+		Scsi_Cmnd *cmd;
+
+		cmd = (Scsi_Cmnd *)p->SCB_array[scbptr];
+		if (!cmd) {
+			printk("aic7xxx_isr: no command for scb (scsiint)\n");
+			/*
+			 *  Turn off the interrupt and set status
+			 *  to zero, so that it falls through the
+			 *  reset of the SCSIINT code.
+			 */
+			outb(status, O_CLRSINT1(base));
+			UNPAUSE_SEQUENCER(p);
+			outb(0x4, O_CLRINT(base));	/* undocumented */
+			status = 0;
+		}
+		p->SCB_array[scbptr] = NULL;
+
+		/*
+		 *  Only the SCSI Status 1 register has information
+		 *  about exceptional conditions that we'd have a
+		 *  SCSIINT about; anything in SSTAT0 will be handled
+		 *  by the sequencer.  Note that there can be multiple
+		 *  bits set.
+		 */
+		if (status & 0x80) {			/* SELTO */
+			/*
+			 *  Hardware selection timer has expired.  Turn
+			 *  off SCSI selection sequence.
+			 */
+			outb(0, O_SCSISEQ(base));
+			cmd->result = DID_TIME_OUT << 16;
+
+			/*
+			 *  If there's an active message, it belongs to the
+			 *  command that is getting punted - remove it.
+			 */
+			outb(0, HA_MSG_FLAGS(base));
+
+			/*
+			 *  Shut off the offending interrupt sources, reset
+			 *  the sequencer address to zero and unpause it,
+			 *  then call the high-level SCSI completion routine.
+			 *
+			 *  WARNING!  This is a magic sequence!  After many
+			 *  hours of guesswork, turning off the SCSI interrupts
+			 *  in CLRSINT? does NOT clear the SCSIINT bit in
+			 *  INTSTAT.  By writing to the (undocumented, unused
+			 *  according to the AIC-7770 manual) third bit of
+			 *  CLRINT, you can clear INTSTAT.  But, if you do it
+			 *  while the sequencer is paused, you get a BRKADRINT
+			 *  with an Illegal Host Address status, so the
+			 *  sequencer has to be restarted first.
+			 */
+			outb(0x80, O_CLRSINT1(base));	/* CLRSELTIMO */
+			RESTART_SEQUENCER(p);
+
+			outb(0x4, O_CLRINT(base));	/* undocumented */
+			cmd->scsi_done(cmd);
+		}
+
+		if (status & 0x4) {			/* SCSIPERR */
+			/*
+			 *  A parity error has occurred during a data
+			 *  transfer phase.  Flag it and continue.
+			 */
+			printk("aic7xxx: parity error on target %d, lun %d\n",
+			       cmd->target,
+			       cmd->lun);
+			aic7xxx_parity(cmd) = DID_PARITY;
+
+			/*
+			 *  Clear interrupt and resume as above.
+			 */
+			outb(0x4, O_CLRSINT1(base));	/* CLRSCSIPERR */
+			UNPAUSE_SEQUENCER(p);
+
+			outb(0x4, O_CLRINT(base));	/* undocumented */
+		}
+
+		if ((status & (0x8|0x4)) == 0 && status) {
+			/*
+			 *  We don't know what's going on.  Turn off the
+			 *  interrupt source and try to continue.
+			 */
+			printk("aic7xxx_isr: sstat1 = 0x%x\n", status);
+			outb(status, O_CLRSINT1(base));
+			UNPAUSE_SEQUENCER(p);
+			outb(0x4, O_CLRINT(base));	/* undocumented */
+		}
+	}
+
+	if (intstat & 0x2) {				/* CMDCMPLT */
+
+		int complete, old_scbptr;
+		struct aic7xxx_scb scb;
+		unsigned actual;
+		Scsi_Cmnd *cmd;
+
+		/*
+		 *  The sequencer will continue running when it
+		 *  issues this interrupt.  There may be >1 commands
+		 *  finished, so loop until we've processed them all.
+		 */
+		do {
+			complete = inb(O_QOUTFIFO(base));
+
+			cmd = (Scsi_Cmnd *)p->SCB_array[complete];
+			if (!cmd) {
+				printk("aic7xxx warning: "
+				       "no command for scb (cmdcmplt)\n");
+				continue;
+			}
+			p->SCB_array[complete] = NULL;
+			
+			PAUSE_SEQUENCER(p);
+
+			/*
+			 *  After pausing the sequencer (and waiting
+			 *  for it to stop), save its SCB pointer, then
+			 *  write in our completed one and read the SCB
+			 *  registers.  Afterwards, restore the saved
+			 *  pointer, unpause the sequencer and call the
+			 *  higher-level completion function - unpause
+			 *  first since we have no idea how long done()
+			 *  will take.
+			 */
+			old_scbptr = inb(O_SCBPTR(base));
+			outb(complete, O_SCBPTR(base));
+
+			aic7xxx_getscb(base, &scb);
+			outb(old_scbptr, O_SCBPTR(base));
+
+			UNPAUSE_SEQUENCER(p);
+
+			cmd->result = scb.target_status |
+				     (aic7xxx_parity(cmd) << 16);
+
+			/*
+			 *  Did we underflow?  At this time, there's only
+			 *  one other driver that bothers to check for this,
+			 *  and cmd->underflow seems to be set rather half-
+			 *  heartedly in the higher-level SCSI code.
+			 */
+			actual = aic7xxx_length(cmd,
+						scb.residual_SG_segment_count);
+
+			actual -= ((scb.residual_data_count[2] << 16) |
+				   (scb.residual_data_count[1] <<  8) |
+				   (scb.residual_data_count[0]));
+
+			if (actual < cmd->underflow) {
+				printk("aic7xxx: target %d underflow - "
+				       "wanted (at least) %u, got %u\n",
+				       cmd->target, cmd->underflow, actual);
+
+				cmd->result = scb.target_status |
+					     (DID_UNDERFLOW << 16);
+			}
+
+			cmd->scsi_done(cmd);
+
+			/*
+			 *  Clear interrupt status before checking
+			 *  the output queue again.  This eliminates
+			 *  a race condition whereby a command could
+			 *  complete between the queue poll and the
+			 *  interrupt clearing, so notification of the
+			 *  command being complete never made it back
+			 *  up to the kernel.
+			 */
+			outb(0x2, O_CLRINT(base));	/* CLRCMDINT */
+
+		} while (inb(O_QOUTCNT(base)));
+	}
+
+	if (intstat & 0x1) {				/* SEQINT */
+
+		unsigned char transfer, offset, rate;
+
+		/*
+		 *  Although the sequencer is paused immediately on
+		 *  a SEQINT, an interrupt for a SCSIINT or a CMDCMPLT
+		 *  condition will have unpaused the sequencer before
+		 *  this point.
+		 */
+		PAUSE_SEQUENCER(p);
+
+		switch (intstat & 0xf0) {
+		    case 0x00:
+			panic("aic7xxx_isr: unknown scsi bus phase\n");
+		    case 0x10:
+			debug("aic7xxx_isr warning: "
+			      "issuing message reject, 1st byte 0x%x\n",
+			      inb(HA_REJBYTE(base)));
+			break;
+		    case 0x20:
+			panic("aic7xxx_isr: reconnecting target %d "
+			      "didn't issue IDENTIFY message\n",
+			      (inb(O_SELID(base)) >> 4) & 0xf);
+		    case 0x30:
+			debug("aic7xxx_isr: sequencer couldn't find match "
+			      "for reconnecting target %d - issuing ABORT\n",
+			      (inb(O_SELID(base)) >> 4) & 0xf);
+			break;
+		    case 0x40:
+			transfer = inb(HA_ARG_1(base));
+			offset = inb(HA_ARG_2(base));
+			aic7xxx_to_scsirate(&rate, transfer, offset);
+			outb(rate, HA_RETURN_1(base));
+			debug_rate(base, rate);
+			break;
+		    default:
+			debug("aic7xxx_isr: seqint, "
+			      "intstat = 0x%x, scsisigi = 0x%x\n",
+			      intstat, inb(O_SCSISIGI(base)));
+			break;
+		}
+
+		outb(0x1, O_CLRINT(base));		/* CLRSEQINT */
+		UNPAUSE_SEQUENCER(p);
+	}
+}
+
+/*
+ *  Probing for EISA boards: it looks like the first two bytes
+ *  are a manufacturer code - three characters, five bits each:
+ *
+ *		 BYTE 0   BYTE 1   BYTE 2   BYTE 3
+ *		?1111122 22233333 PPPPPPPP RRRRRRRR
+ *
+ *  The characters are baselined off ASCII '@', so add that value
+ *  to each to get the real ASCII code for it.  The next two bytes
+ *  appear to be a product and revision number, probably vendor-
+ *  specific.  This is what is being searched for at each port,
+ *  and what should probably correspond to the ID= field in the
+ *  ECU's .cfg file for the card - if your card is not detected,
+ *  make sure your signature is listed in the array.
+ *
+ *  The fourth byte's lowest bit seems to be an enabled/disabled
+ *  flag (rest of the bits are reserved?).
+ */
+
+static
+enum aha_type aic7xxx_probe(int slot, int s_base)
+{
+	int i;
+	unsigned char buf[4];
+
+	static struct {
+		int n;
+		unsigned char signature[sizeof(buf)];
+		enum aha_type type;
+	} S[] = {
+		4, { 0x04, 0x90, 0x77, 0x71 }, T_274X,	/* host adapter 274x */
+		4, { 0x04, 0x90, 0x77, 0x70 }, T_274X,	/* motherboard 274x  */
+		4, { 0x04, 0x90, 0x77, 0x56 }, T_284X,	/* 284x, BIOS enabled */
+	};
+
+	for (i = 0; i < sizeof(buf); i++) {
+		/*
+		 *  The VL-bus cards need to be primed by
+		 *  writing before a signature check.
+		 */
+		outb(0x80 + i, s_base);
+		buf[i] = inb(s_base + i);
+	}
+
+	for (i = 0; i < sizeof(S)/sizeof(S[0]); i++) {
+		if (!memcmp(buf, S[i].signature, S[i].n)) {
+			/*
+			 *  Signature match on enabled card?
+			 */
+			if (inb(s_base + 4) & 1)
+				return(S[i].type);
+			printk("aic7xxx disabled at slot %d, ignored\n", slot);
+		}
+	}
+	return(T_NONE);
+}
+
+/*
+ *  Return ' ' for plain 274x, 'T' for twin-channel, 'W' for
+ *  wide channel, '?' for anything else.
+ */
+
+static
+char aic7xxx_type(int base)
+{
+	/*
+	 *  AIC-7770/7870s can be wired so that, on chip reset,
+	 *  the SCSI Block Control register indicates how many
+	 *  busses the chip is configured for.  The two high bits
+	 *  set indicate a 294x.
+	 */
+	switch (inb(O_SBLKCTL(base))) {
+	    case 0:
+	    case 0xc0:
+		return(' ');
+	    case 2:
+	    case 0xc2:
+		return('W');
+	    case 8:
+		return('T');
+	    default:
+		printk("aic7xxx has unknown bus configuration\n");
+		return('?');
+	}
+}
+
+static
+void aic7xxx_loadram(int base)
+{
+	static unsigned char seqprog[] = {
+		/*
+		 *  Each sequencer instruction is 29 bits
+		 *  long (fill in the excess with zeroes)
+		 *  and has to be loaded from least -> most
+		 *  significant byte, so this table has the
+		 *  byte ordering reversed.
+		 */
+#		include "aic7xxx_seq.h"
+	};
+
+	/*
+	 *  When the AIC-7770 is paused (as on chip reset), the
+	 *  sequencer address can be altered and a sequencer
+	 *  program can be loaded by writing it, byte by byte, to
+	 *  the sequencer RAM port - the Adaptec documentation
+	 *  recommends using REP OUTSB to do this, hence the inline
+	 *  assembly.  Since the address autoincrements as we load
+	 *  the program, reset it back to zero afterward.  Disable
+	 *  sequencer RAM parity error detection while loading, and
+	 *  make sure the LOADRAM bit is enabled for loading.
+	 */
+	outb(0x83, O_SEQCTL(base));	/* PERRORDIS|SEQRESET|LOADRAM */
+
+	asm volatile("cld\n\t"
+		     "rep\n\t"
+		     "outsb"
+		     : /* no output */
+		     :"S" (seqprog), "c" (sizeof(seqprog)), "d" (O_SEQRAM(base))
+		     :"si", "cx", "dx");
+
+	/*
+	 *  WARNING!  This is a magic sequence!  After extensive
+	 *  experimentation, it seems that you MUST turn off the
+	 *  LOADRAM bit before you play with SEQADDR again, else
+	 *  you will end up with parity errors being flagged on
+	 *  your sequencer program.  (You would also think that
+	 *  turning off LOADRAM and setting SEQRESET to reset the
+	 *  address to zero would work, but you need to do it twice
+	 *  for it to take effect on the address.  Timing problem?)
+	 */
+	outb(0, O_SEQCTL(base));
+	do {
+		/*
+		 *  Actually, reset it until
+		 *  the address shows up as
+		 *  zero just to be safe..
+		 */
+		outb(0x2, O_SEQCTL(base));	/* SEQRESET */
+
+	} while (inb(O_SEQADDR(base)) != 0 && inb(O_SEQADDR(base) + 1) != 0);
+}
+
+static
+void aha274x_config(struct aic7xxx_host_config *p, va_list ap)
+{
+	int base = va_arg(ap, int);
+
+	/*
+	 *  Give the AIC-7770 a reset - reading the 274x's registers
+	 *  returns zeroes unless you do.  This forces a pause of the
+	 *  Sequencer.
+	 */
+	outb(1, O_HCNTRL(base));	/* CHIPRST */
+
+	p->base = base;
+	p->irq = inb(HA_INTDEF(base)) & 0xf;
+	p->scsi_id = inb(HA_SCSICONF(base)) & 0x7;
+
+	/*
+	 *  This value for HCNTRL may be changed in the ISR if we
+	 *  catch a spurious interrupt right away.
+	 */
+	p->unpause = 0xa;
+
+	/*
+	 *  XXX - these are values that I don't know how to query
+	 *	  the hardware for.  Apparently some revision E
+	 *	  '7770s can have more SCBs, and I don't know how
+	 *	  to get the "extended translation" flag from the
+	 *	  EISA data area.
+	 */
+	p->maxscb = 4;
+	p->extended = aic7xxx_extended;
+
+	/*
+	 *  A reminder until this can be detected automatically.
+	 */
+	printk("aha274x: extended translation %sabled\n",
+		p->extended ? "en" : "dis");
+}
+
+static
+void aha284x_config(struct aic7xxx_host_config *p, va_list ap)
+{
+	int base = va_arg(ap, int);
+
+	/*
+	 *  Give the AIC-7770 a reset - this forces a pause of the
+	 *  Sequencer and returns everything to default values.
+	 */
+	outb(1, O_HCNTRL(base));	/* CHIPRST */
+
+	p->base = base;
+	p->unpause = 0x2;
+	p->irq = inb(HA_INTDEF(base)) & 0xf;
+	p->scsi_id = inb(HA_SCSICONF(base)) & 0x7;
+
+	/*
+	 *  XXX - these are values that I don't know how to query
+	 *	  the hardware for.  Apparently some revision E
+	 *	  '7770s can have more SCBs, and I don't know how
+	 *	  to get the "extended translation" flag from the
+	 *	  onboard memory.
+	 */
+	p->maxscb = 4;
+	p->extended = aic7xxx_extended;
+
+	/*
+	 *  A reminder until this can be detected automatically.
+	 */
+	printk("aha284x: extended translation %sabled\n",
+		p->extended ? "en" : "dis");
+}
+
+static
+void aha294x_config(struct aic7xxx_host_config *p, va_list ap)
+{
+	int error;
+	unsigned long io_port;
+	unsigned char bus, device_fn, irq;
+
+	bus = va_arg(ap, unsigned char);
+	device_fn = va_arg(ap, unsigned char);
+
+	/*
+	 *  Read esundry information from PCI BIOS.
+	 */
+	error = pcibios_read_config_dword(bus,
+					  device_fn,
+					  PCI_BASE_ADDRESS_0,
+					  &io_port);
+	if (error) {
+		panic("aha294x_config: error %s reading i/o port\n",
+		      pcibios_strerror(error));
+	}
+
+	error = pcibios_read_config_byte(bus,
+					 device_fn,
+					 PCI_INTERRUPT_LINE,
+					 &irq);
+	if (error) {
+		panic("aha294x_config: error %s reading irq\n",
+		      pcibios_strerror(error));
+	}
+
+	/*
+	 *  Make the base I/O register look like EISA and VL-bus.
+	 */
+	p->base = io_port - 0xc01;
+
+	/*
+	 *  Give the AIC-7870 a reset - this forces a pause of the
+	 *  Sequencer and returns everything to default values.
+	 */
+	outb(1, O_HCNTRL(p->base));	/* CHIPRST */
+
+	p->irq = irq;
+	p->maxscb = 16;
+	p->unpause = 0xa;
+
+	/*
+	 *  XXX - these are values that I don't know how to query
+	 *	  the hardware for, so for now the SCSI host ID is
+	 *	  hardwired to 7, and the "extended translation"
+	 *	  flag is taken from boot-time flags.
+	 */
+	p->scsi_id = 7;
+	p->extended = aic7xxx_extended;
+
+	/*
+	 *  XXX - force data fifo threshold to 100%.  Why does this
+	 *	  need to be done?
+	 */
+#	define	DFTHRESH	3
+
+	outb(DFTHRESH << 6, O_DSPCISTATUS(p->base));
+	outb(p->scsi_id | (DFTHRESH << 6), HA_SCSICONF(p->base));
+
+	/*
+	 *  A reminder until this can be detected automatically.
+	 */
+	printk("aha294x: extended translation %sabled\n",
+		p->extended ? "en" : "dis");
+}
+
+static
+int aic7xxx_register(Scsi_Host_Template *template, enum aha_type type, ...)
+{
+	va_list ap;
+	int i, base;
+	struct Scsi_Host *host;
+	struct aic7xxx_host *p;
+	struct aic7xxx_host_config config;
+
+	va_start(ap, type);
+	
+	switch (type) {
+	    case T_274X:
+		aha274x_config(&config, ap);
+		break;
+	    case T_284X:
+		aha284x_config(&config, ap);
+		break;
+	    case T_294X:
+		aha294x_config(&config, ap);
+		break;
+	    default:
+		panic("aic7xxx_register: internal error\n");
+	}
+	va_end(ap);
+
+	base = config.base;
+
+	/*
+	 *  The IRQ level in i/o port 4 maps directly onto the real
+	 *  IRQ number.  If it's ok, register it with the kernel.
+	 *
+	 *  NB. the Adaptec documentation says the IRQ number is only
+	 *	in the lower four bits; the ECU information shows the
+	 *	high bit being used as well.  Which is correct?
+	 */
+	if (config.irq < 9 || config.irq > 15) {
+		printk("aic7xxx uses unsupported IRQ level, ignoring\n");
+		return(0);
+	}
+	
+	/*
+	 *  Lock out other contenders for our i/o space.
+	 */
+	snarf_region(O_MINREG(base), O_MAXREG(base)-O_MINREG(base));
+
+	/*
+	 *  Any card-type-specific adjustments before we register
+	 *  the scsi host(s).
+	 */
+	switch (aic7xxx_type(base)) {
+	    case 'T':
+		printk("aic7xxx warning: ignoring channel B of 274x-twin\n");
+		break;
+	    case ' ':
+		break;
+	    default:
+		printk("aic7xxx is an unsupported type, ignoring\n");
+		return(0);
+	}
+
+	/*
+	 *  Before registry, make sure that the offsets of the
+	 *  struct scatterlist are what the sequencer will expect,
+	 *  otherwise disable scatter-gather altogether until someone
+	 *  can fix it.  This is important since the sequencer will
+	 *  DMA elements of the SG array in while executing commands.
+	 */
+	if (template->sg_tablesize != SG_NONE) {
+		struct scatterlist sg;
+
+		if (SG_STRUCT_CHECK(sg)) {
+			printk("aic7xxx warning: kernel scatter-gather "
+			       "structures changed, disabling it\n");
+			template->sg_tablesize = SG_NONE;
+		}
+	}
+	
+	/*
+	 *  Register each "host" and fill in the returned Scsi_Host
+	 *  structure as best we can.  Some of the parameters aren't
+	 *  really relevant for bus types beyond ISA, and none of the
+	 *  high-level SCSI code looks at it anyway.. why are the fields
+	 *  there?  Also save the pointer so that we can find the
+	 *  information when an IRQ is triggered.
+	 */
+	host = scsi_register(template, sizeof(struct aic7xxx_host));
+	host->can_queue = config.maxscb;
+	host->this_id = config.scsi_id;
+	host->irq = config.irq;
+
+	aic7xxx_boards[config.irq] = host;
+	
+	p = (struct aic7xxx_host *)host->hostdata;
+	for (i = 0; i < AIC7XXX_MAXSCB; i++)
+		p->SCB_array[i] = NULL;
+
+	p->base = config.base;
+	p->maxscb = config.maxscb;
+	p->extended = config.extended;
+
+	/*
+	 *  The interrupt trigger is different depending
+	 *  on whether the card is EISA or VL-bus - sometimes.
+	 *  The startup variable will be cleared once the first
+	 *  command is queued, and is checked in the isr to
+	 *  try and detect when the interrupt type is set
+	 *  incorrectly, triggering an interrupt immediately.
+	 *  This is now just set on a per-card-type basis.
+	 */
+	p->unpause = config.unpause;
+	p->startup = !0;
+
+	/*
+	 *  Register IRQ with the kernel _after_ the host information
+	 *  is set up, in case we take an interrupt right away, due to
+	 *  the interrupt type being set wrong.
+	 */
+	if (request_irq(config.irq, aic7xxx_isr, SA_INTERRUPT, "aic7xxx")) {
+		printk("aic7xxx couldn't register irq %d, ignoring\n",
+		       config.irq);
+		return(0);
+	}
+
+	/*
+	 *  Print out debugging information before re-enabling
+	 *  the card - a lot of registers on it can't be read
+	 *  when the sequencer is active.
+	 */
+#ifdef AIC7XXX_DEBUG
+	debug_config(type, &config);
+#endif
+
+	/*
+	 *  Load the sequencer program, then re-enable the board -
+	 *  resetting the AIC-7770 disables it, leaving the lights
+	 *  on with nobody home.  On the PCI bus you *may* be home,
+	 *  but then your mailing address is dynamically assigned
+	 *  so no one can find you anyway :-)
+	 */
+	aic7xxx_loadram(base);
+	if (type != T_294X)
+		outb(1, O_BCTL(base));	/* ENABLE */
+
+	/*
+	 *  Set the host adapter registers to indicate that synchronous
+	 *  negotiation should be attempted the first time the targets
+	 *  are communicated with.  Also initialize the active message
+	 *  flag to indicate that there is no message.
+	 */
+	outb(0xff, HA_NEEDSDTR(base));
+	outb(0, HA_MSG_FLAGS(base));
+
+	/*
+	 *  For reconnecting targets, the sequencer code needs to
+	 *  know how many SCBs it has to search through.
+	 */
+	outb(config.maxscb, HA_SCBCOUNT(base));
+
+	/*
+	 *  Unpause the sequencer before returning and enable
+	 *  interrupts - we shouldn't get any until the first
+	 *  command is sent to us by the high-level SCSI code.
+	 */
+	UNPAUSE_SEQUENCER(p);
+	return(1);
+}
+
+int aic7xxx_detect(Scsi_Host_Template *template)
+{
+	enum aha_type type;
+	int found = 0, slot, base;
+
+	/*
+	 *  EISA/VL-bus card signature probe.
+	 */
+	for (slot = MINSLOT; slot <= MAXSLOT; slot++) {
+
+		base = SLOTBASE(slot);
+		
+		if (check_region(O_MINREG(base),
+				 O_MAXREG(base)-O_MINREG(base)))
+		{
+			/*
+			 *  Some other driver has staked a
+			 *  claim to this i/o region already.
+			 */
+			continue;
+		}
+
+		type = aic7xxx_probe(slot, O_BIDx(base));
+
+		if (type != T_NONE) {
+			/*
+			 *  We "find" a 274x if we locate the card
+			 *  signature and we can set it up and register
+			 *  it with the kernel without incident.
+			 */
+			found += aic7xxx_register(template, type, base);
+		}
+	}
+
+	/*
+	 *  PCI-bus probe.
+	 */
+	if (pcibios_present()) {
+		int index = 0;
+		unsigned char bus, device_fn;
+
+		while (!pcibios_find_device(PCI_VENDOR_ID_ADAPTEC,
+					    PCI_DEVICE_ID_ADAPTEC_2940,
+					    index,
+					    &bus,
+					    &device_fn))
+		{
+			found += aic7xxx_register(template, T_294X,
+						  bus, device_fn);
+			index += 1;
+		}
+	}
+
+	template->name = (char *)aic7xxx_info(NULL);
+	return(found);
+}
+
+const char *aic7xxx_info(struct Scsi_Host *notused)
+{
+	return("Adaptec AHA274x/284x/294x (EISA/VL-bus/PCI -> Fast SCSI) "
+	       AIC7XXX_SEQ_VERSION "/"
+	       AIC7XXX_H_VERSION "/"
+	       "1.34");
+}
+
+static
+void aic7xxx_buildscb(struct aic7xxx_host *p,
+		      Scsi_Cmnd *cmd,
+		      struct aic7xxx_scb *scb)
+{
+	void *addr;
+	unsigned length;
+
+	memset(scb, 0, sizeof(*scb));
+
+	/*
+	 *  NB. channel selection (bit 3) is always zero.
+	 */
+	scb->target_channel_lun = ((cmd->target << 4) & 0xf0) |
+				   (cmd->lun & 0x7);
+
+	/*
+	 *  The interpretation of request_buffer and request_bufflen
+	 *  changes depending on whether or not use_sg is zero; a
+	 *  non-zero use_sg indicates the number of elements in the
+	 *  scatter-gather array.
+	 *
+	 *  The AIC-7770 can't support transfers of any sort larger
+	 *  than 2^24 (three-byte count) without backflips.  For what
+	 *  the kernel is doing, this shouldn't occur.  I hope.
+	 */
+	length = aic7xxx_length(cmd, 0);
+
+	/*
+	 *  The sequencer code cannot yet handle scatter-gather segments
+	 *  larger than 64k (two-byte length).  The 1.1.x kernels, however,
+	 *  have a four-byte length field in the struct scatterlist, so
+	 *  make sure we don't exceed 64k on these kernels for now.
+	 */
+	aic7xxx_sg_check(cmd);
+
+	if (length > 0xffffff) {
+		panic("aic7xxx_buildscb: can't transfer > 2^24 - 1 bytes\n");
+	}
+
+	/*
+	 *  XXX - this relies on the host data being stored in a
+	 *	  little-endian format.
+	 */
+	addr = cmd->cmnd;
+	scb->SCSI_cmd_length = cmd->cmd_len;
+	memcpy(scb->SCSI_cmd_pointer, &addr, sizeof(scb->SCSI_cmd_pointer));
+
+	if (cmd->use_sg) {
+#if 0
+		debug("aic7xxx_buildscb: SG used, %d segments, length %u\n",
+		      cmd->use_sg,
+		      length);
+#endif
+		scb->SG_segment_count = cmd->use_sg;
+		memcpy(scb->SG_list_pointer,
+		       &cmd->request_buffer,
+		       sizeof(scb->SG_list_pointer));
+	} else {
+		scb->SG_segment_count = 0;
+		memcpy(scb->data_pointer,
+		       &cmd->request_buffer,
+		       sizeof(scb->data_pointer));
+		memcpy(scb->data_count,
+		       &cmd->request_bufflen,
+		       sizeof(scb->data_count));
+	}
+}
+
+static
+void aic7xxx_putscb(int base, struct aic7xxx_scb *scb)
+{
+	/*
+	 *  By turning on the SCB auto increment, any reference
+	 *  to the SCB I/O space postincrements the SCB address
+	 *  we're looking at.  So turn this on and dump the relevant
+	 *  portion of the SCB to the card.
+	 */
+	outb(0x80, O_SCBCNT(base));	/* SCBAUTO */
+
+	asm volatile("cld\n\t"
+		     "rep\n\t"
+		     "outsb"
+		     : /* no output */
+		     :"S" (scb), "c" (sizeof(*scb)), "d" (O_SCBARRAY(base))
+		     :"si", "cx", "dx");
+
+	outb(0, O_SCBCNT(base));
+}
+
+int aic7xxx_queue(Scsi_Cmnd *cmd, void (*fn)(Scsi_Cmnd *))
+{
+	long flags;
+	int empty, old_scbptr;
+	struct aic7xxx_host *p;
+	struct aic7xxx_scb scb;
+
+#if 0
+	debug("aic7xxx_queue: cmd 0x%x (size %u), target %d, lun %d\n",
+	      cmd->cmnd[0],
+	      cmd->cmd_len,
+	      cmd->target,
+	      cmd->lun);
+#endif
+
+	p = (struct aic7xxx_host *)cmd->host->hostdata;
+
+	/*
+	 *  Construct the SCB beforehand, so the sequencer is
+	 *  paused a minimal amount of time.
+	 */
+	aic7xxx_buildscb(p, cmd, &scb);
+
+	/*
+	 *  Clear the startup flag - we can now legitimately
+	 *  expect interrupts.
+	 */
+	p->startup = 0;
+
+	/*
+	 *  This is a critical section, since we don't want the
+	 *  interrupt routine mucking with the host data or the
+	 *  card.  Since the kernel documentation is vague on
+	 *  whether or not we are in a cli/sti pair already, save
+	 *  the flags to be on the safe side.
+	 */
+	save_flags(flags);
+	cli();
+
+	/*
+	 *  Find a free slot in the SCB array to load this command
+	 *  into.  Since can_queue is set to the maximum number of
+	 *  SCBs for the card, we should always find one.
+	 */
+	for (empty = 0; empty < p->maxscb; empty++)
+		if (!p->SCB_array[empty])
+			break;
+	if (empty == p->maxscb)
+		panic("aic7xxx_queue: couldn't find a free scb\n");
+
+	/*
+	 *  Pause the sequencer so we can play with its registers -
+	 *  wait for it to acknowledge the pause.
+	 *
+	 *  XXX - should the interrupts be left on while doing this?
+	 */
+	PAUSE_SEQUENCER(p);
+
+	/*
+	 *  Save the SCB pointer and put our own pointer in - this
+	 *  selects one of the four banks of SCB registers.  Load
+	 *  the SCB, then write its pointer into the queue in FIFO
+	 *  and restore the saved SCB pointer.
+	 */
+	old_scbptr = inb(O_SCBPTR(p->base));
+	outb(empty, O_SCBPTR(p->base));
+	
+	aic7xxx_putscb(p->base, &scb);
+
+	outb(empty, O_QINFIFO(p->base));
+	outb(old_scbptr, O_SCBPTR(p->base));
+
+	/*
+	 *  Make sure the Scsi_Cmnd pointer is saved, the struct it
+	 *  points to is set up properly, and the parity error flag
+	 *  is reset, then unpause the sequencer and watch the fun
+	 *  begin.
+	 */
+	cmd->scsi_done = fn;
+	p->SCB_array[empty] = cmd;
+	aic7xxx_parity(cmd) = DID_OK;
+
+	UNPAUSE_SEQUENCER(p);
+
+	restore_flags(flags);
+	return(0);
+}
+
+/* return values from aic7xxx_kill */
+
+enum k_state {
+	k_ok,				/* scb found and message sent */
+	k_busy,				/* message already present */
+	k_absent,			/* couldn't locate scb */
+	k_disconnect,			/* scb found, but disconnected */
+};
+
+/*
+ *  This must be called with interrupts disabled - it's going to
+ *  be messing around with the host data, and an interrupt being
+ *  fielded in the middle could get ugly.
+ *
+ *  Since so much of the abort and reset code is shared, this
+ *  function performs more magic than it really should.  If the
+ *  command completes ok, then it will call scsi_done with the
+ *  result code passed in.  The unpause parameter controls whether
+ *  or not the sequencer gets unpaused - the reset function, for
+ *  instance, may want to do something more aggressive.
+ *
+ *  Note that the command is checked for in our SCB_array first
+ *  before the sequencer is paused, so if k_absent is returned,
+ *  then the sequencer is NOT paused.
+ */
+
+static
+enum k_state aic7xxx_kill(Scsi_Cmnd *cmd, unsigned char message,
+			  unsigned int result, int unpause)
+{
+	struct aic7xxx_host *p;
+	int i, scb, found, queued;
+	unsigned char scbsave[AIC7XXX_MAXSCB];
+
+	p = (struct aic7xxx_host *)cmd->host->hostdata;
+
+	/*
+	 *  If we can't find the command, assume it just completed
+	 *  and shrug it away.
+	 */
+	for (scb = 0; scb < p->maxscb; scb++)
+		if (p->SCB_array[scb] == cmd)
+			break;
+
+	if (scb == p->maxscb)
+		return(k_absent);
+
+	PAUSE_SEQUENCER(p);
+
+	/*
+	 *  This is the best case, really.  Check to see if the
+	 *  command is still in the sequencer's input queue.  If
+	 *  so, simply remove it.  Reload the queue afterward.
+	 */
+	queued = inb(O_QINCNT(p->base));
+	
+	for (i = found = 0; i < queued; i++) {
+		scbsave[i] = inb(O_QINFIFO(p->base));
+
+		if (scbsave[i] == scb) {
+			found = 1;
+			i -= 1;
+		}
+	}
+
+	queued -= found;
+	for (i = 0; i < queued; i++)
+		outb(scbsave[i], O_QINFIFO(p->base));
+
+	if (found)
+		goto complete;
+
+	/*
+	 *  Check the current SCB bank.  If it's not the one belonging
+	 *  to the command we want to kill, assume that the command
+	 *  is disconnected.  It's rather a pain to force a reconnect
+	 *  and send a message to the target, so we abdicate responsibility
+	 *  in this case.
+	 */
+	if (inb(O_SCBPTR(p->base)) != scb) {
+		if (unpause)
+			UNPAUSE_SEQUENCER(p);
+		return(k_disconnect);
+	}
+
+	/*
+	 *  Presumably at this point our target command is active.  Check
+	 *  to see if there's a message already in effect.  If not, place
+	 *  our message in and assert ATN so the target goes into MESSAGE
+	 *  OUT phase.
+	 */
+	if (inb(HA_MSG_FLAGS(p->base)) & 0x80) {
+		if (unpause)
+			UNPAUSE_SEQUENCER(p);
+		return(k_busy);
+	}
+
+	outb(0x80, HA_MSG_FLAGS(p->base));		/* active message */
+	outb(1, HA_MSG_LEN(p->base));			/* length = 1 */
+	outb(message, HA_MSG_START(p->base));		/* message body */
+
+	/*
+	 *  Assert ATN.  Use the value of SCSISIGO saved by the
+	 *  sequencer code so we don't alter its contents radically
+	 *  in the middle of something critical.
+	 */
+	outb(inb(HA_SIGSTATE(p->base)) | 0x10, O_SCSISIGO(p->base));
+
+	/*
+	 *  The command has been killed.  Do the bookkeeping, unpause
+	 *  the sequencer, and notify the higher-level SCSI code.
+	 */
+complete:
+	p->SCB_array[scb] = NULL;
+	if (unpause)
+		UNPAUSE_SEQUENCER(p);
+
+	cmd->result = result << 16;
+	cmd->scsi_done(cmd);
+	return(k_ok);
+}
+
+int aic7xxx_abort(Scsi_Cmnd *cmd)
+{
+	int rv;
+	long flags;
+
+	save_flags(flags);
+	cli();
+
+	switch (aic7xxx_kill(cmd, ABORT, DID_ABORT, !0)) {
+	    case k_ok:		rv = SCSI_ABORT_SUCCESS;	break;
+	    case k_busy:	rv = SCSI_ABORT_BUSY;		break;
+	    case k_absent:	rv = SCSI_ABORT_NOT_RUNNING;	break;
+	    case k_disconnect:	rv = SCSI_ABORT_SNOOZE;		break;
+	    default:
+		panic("aic7xxx_do_abort: internal error\n");
+	}
+
+	restore_flags(flags);
+	return(rv);
+}
+
+/*
+ *  Resetting the bus always succeeds - is has to, otherwise the
+ *  kernel will panic!  Try a surgical technique - sending a BUS
+ *  DEVICE RESET message - on the offending target before pulling
+ *  the SCSI bus reset line.
+ */
+
+int aic7xxx_reset(Scsi_Cmnd *cmd)
+{
+	int i;
+	long flags;
+	Scsi_Cmnd *reset;
+	struct aic7xxx_host *p;
+
+	p = (struct aic7xxx_host *)cmd->host->hostdata;
+	save_flags(flags);
+	cli();
+
+	switch (aic7xxx_kill(cmd, BUS_DEVICE_RESET, DID_RESET, 0)) {
+
+	    case k_ok:
+		/*
+		 *  The RESET message was sent to the target
+		 *  with no problems.  Flag that target as
+		 *  needing a SDTR negotiation on the next
+		 *  connection and restart the sequencer.
+		 */
+		outb((1 << cmd->target), HA_NEEDSDTR(p->base));
+		UNPAUSE_SEQUENCER(p);
+		break;
+
+	    case k_absent:
+		/*
+		 *  The sequencer will not be paused if aic7xxx_kill()
+		 *  couldn't find the command.
+		 */
+		PAUSE_SEQUENCER(p);
+		/* falls through */
+
+	    case k_busy:
+	    case k_disconnect:
+		/*
+		 *  Do a hard reset of the SCSI bus.  According to the
+		 *  SCSI-2 draft specification, reset has to be asserted
+		 *  for at least 25us.  I'm invoking the kernel delay
+		 *  function for 30us since I'm not totally trusting of
+		 *  the busy loop timing.
+		 *
+		 *  XXX - I'm not convinced this works.  I tried resetting
+		 *	  the bus before, trying to get the devices on the
+		 *	  bus to revert to asynchronous transfer, and it
+		 *	  never seemed to work.
+		 */
+		debug("aic7xxx: attempting to reset scsi bus and card\n");
+
+		outb(1, O_SCSISEQ(p->base));		/* SCSIRSTO */
+		udelay(30);
+		outb(0, O_SCSISEQ(p->base));		/* !SCSIRSTO */
+
+		outb(0xff, HA_NEEDSDTR(p->base));
+		UNPAUSE_SEQUENCER(p);
+
+		/*
+		 *  Locate the command and return a "reset" status
+		 *  for it.  This is not completely correct and will
+		 *  probably return to haunt me later.
+		 */
+		for (i = 0; i < p->maxscb; i++) {
+			if (cmd == p->SCB_array[i]) {
+				reset = (Scsi_Cmnd *)p->SCB_array[i];
+				p->SCB_array[i] = NULL;
+				reset->result = DID_RESET << 16;
+				reset->scsi_done(reset);
+				break;
+			}
+		}
+		break;
+
+	    default:
+		panic("aic7xxx_reset: internal error\n");
+	}
+
+	restore_flags(flags);
+	return(SCSI_RESET_SUCCESS);
+}
+
+int aic7xxx_biosparam(Disk *disk, int devno, int geom[])
+{
+	int heads, sectors, cylinders;
+	struct aic7xxx_host *p;
+	
+	p = (struct aic7xxx_host *)disk->device->host->hostdata;
+
+	/*
+	 *  XXX - if I could portably find the card's configuration
+	 *	  information, then this could be autodetected instead
+	 *	  of left to a boot-time switch.
+	 */
+	heads = 64;
+	sectors = 32;
+	cylinders = disk->capacity / (heads * sectors);
+
+	if (p->extended && cylinders > 1024) {
+		heads = 255;
+		sectors = 63;
+		cylinders = disk->capacity / (255 * 63);
+	}
+
+	geom[0] = heads;
+	geom[1] = sectors;
+	geom[2] = cylinders;
+
+	return(0);
+}
+

FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen, slshen@lbl.gov with Sam's (original) version
of this