wd33c93.c

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/*
 * Copyright (c) 1996 John Shifflett, GeoLog Consulting
 *    [e-mail]
 *    [e-mail]
 *
 * 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, 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.
 */

/*
 * Drew Eckhardt's excellent 'Generic NCR5380' sources from Linux-PC
 * provided much of the inspiration and some of the code for this
 * driver. Everything I know about Amiga DMA was gleaned from careful
 * reading of Hamish Mcdonald's original wd33c93 driver; in fact, I
 * borrowed shamelessly from all over that source. Thanks Hamish!
 *
 * _This_ driver is (I feel) an improvement over the old one in
 * several respects:
 *
 *    -  Target Disconnection/Reconnection  is now supported. Any
 *          system with more than one device active on the SCSI bus
 *          will benefit from this. The driver defaults to what I
 *          call 'adaptive disconnect' - meaning that each command
 *          is evaluated individually as to whether or not it should
 *          be run with the option to disconnect/reselect (if the
 *          device chooses), or as a "SCSI-bus-hog".
 *
 *    -  Synchronous data transfers are now supported. Because of
 *          a few devices that choke after telling the driver that
 *          they can do sync transfers, we don't automatically use
 *          this faster protocol - it can be enabled via the command-
 *          line on a device-by-device basis.
 *
 *    -  Runtime operating parameters can now be specified through
 *       the 'amiboot' or the 'insmod' command line. For amiboot do:
 *          "amiboot [usual stuff] wd33c93=blah,blah,blah"
 *       The defaults should be good for most people. See the comment
 *       for 'setup_strings' below for more details.
 *
 *    -  The old driver relied exclusively on what the Western Digital
 *          docs call "Combination Level 2 Commands", which are a great
 *          idea in that the CPU is relieved of a lot of interrupt
 *          overhead. However, by accepting a certain (user-settable)
 *          amount of additional interrupts, this driver achieves
 *          better control over the SCSI bus, and data transfers are
 *          almost as fast while being much easier to define, track,
 *          and debug.
 *
 *
 * TODO:
 *       more speed. linked commands.
 *
 *
 * People with bug reports, wish-lists, complaints, comments,
 * or improvements are asked to pah-leeez email me (John Shifflett)
 * at [e-mail] or [e-mail]! I'm anxious to get
 * this thing into as good a shape as possible, and I'm positive
 * there are lots of lurking bugs and "Stupid Places".
 *
 * Updates:
 *
 * Added support for pre -A chips, which don't have advanced features
 * and will generate CSR_RESEL rather than CSR_RESEL_AM.
 *	Richard Hirst <[e-mail]>  August 2000
 *
 * Added support for Burst Mode DMA and Fast SCSI. Enabled the use of
 * default_sx_per for asynchronous data transfers. Added adjustment
 * of transfer periods in sx_table to the actual input-clock.
 *  peter fuerst <[e-mail]>  February 2007
 */

#include <linux/module.h>

#include <linux/string.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/blkdev.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>

#include <asm/irq.h>

#include "wd33c93.h"

#define optimum_sx_per(hostdata) (hostdata)->sx_table[1].period_ns


#define WD33C93_VERSION    "1.26++"
#define WD33C93_DATE       "10/Feb/2007"

MODULE_AUTHOR("John Shifflett");
MODULE_DESCRIPTION("Generic WD33C93 SCSI driver");
MODULE_LICENSE("GPL");

/*
 * 'setup_strings' is a single string used to pass operating parameters and
 * settings from the kernel/module command-line to the driver. 'setup_args[]'
 * is an array of strings that define the compile-time default values for
 * these settings. If Linux boots with an amiboot or insmod command-line,
 * those settings are combined with 'setup_args[]'. Note that amiboot
 * command-lines are prefixed with "wd33c93=" while insmod uses a
 * "setup_strings=" prefix. The driver recognizes the following keywords
 * (lower case required) and arguments:
 *
 * -  nosync:bitmask -bitmask is a byte where the 1st 7 bits correspond with
 *                    the 7 possible SCSI devices. Set a bit to negotiate for
 *                    asynchronous transfers on that device. To maintain
 *                    backwards compatibility, a command-line such as
 *                    "wd33c93=255" will be automatically translated to
 *                    "wd33c93=nosync:0xff".
 * -  nodma:x        -x = 1 to disable DMA, x = 0 to enable it. Argument is
 *                    optional - if not present, same as "nodma:1".
 * -  period:ns      -ns is the minimum # of nanoseconds in a SCSI data transfer
 *                    period. Default is 500; acceptable values are 250 - 1000.
 * -  disconnect:x   -x = 0 to never allow disconnects, 2 to always allow them.
 *                    x = 1 does 'adaptive' disconnects, which is the default
 *                    and generally the best choice.
 * -  debug:x        -If 'DEBUGGING_ON' is defined, x is a bit mask that causes
 *                    various types of debug output to printed - see the DB_xxx
 *                    defines in wd33c93.h
 * -  clock:x        -x = clock input in MHz for WD33c93 chip. Normal values
 *                    would be from 8 through 20. Default is 8.
 * -  burst:x        -x = 1 to use Burst Mode (or Demand-Mode) DMA, x = 0 to use
 *                    Single Byte DMA, which is the default. Argument is
 *                    optional - if not present, same as "burst:1".
 * -  fast:x         -x = 1 to enable Fast SCSI, which is only effective with
 *                    input-clock divisor 4 (WD33C93_FS_16_20), x = 0 to disable
 *                    it, which is the default.  Argument is optional - if not
 *                    present, same as "fast:1".
 * -  next           -No argument. Used to separate blocks of keywords when
 *                    there's more than one host adapter in the system.
 *
 * Syntax Notes:
 * -  Numeric arguments can be decimal or the '0x' form of hex notation. There
 *    _must_ be a colon between a keyword and its numeric argument, with no
 *    spaces.
 * -  Keywords are separated by commas, no spaces, in the standard kernel
 *    command-line manner.
 * -  A keyword in the 'nth' comma-separated command-line member will overwrite
 *    the 'nth' element of setup_args[]. A blank command-line member (in
 *    other words, a comma with no preceding keyword) will _not_ overwrite
 *    the corresponding setup_args[] element.
 * -  If a keyword is used more than once, the first one applies to the first
 *    SCSI host found, the second to the second card, etc, unless the 'next'
 *    keyword is used to change the order.
 *
 * Some amiboot examples (for insmod, use 'setup_strings' instead of 'wd33c93'):
 * -  wd33c93=nosync:255
 * -  wd33c93=nodma
 * -  wd33c93=nodma:1
 * -  wd33c93=disconnect:2,nosync:0x08,period:250
 * -  wd33c93=debug:0x1c
 */

/* Normally, no defaults are specified */
static char *setup_args[] = { "", "", "", "", "", "", "", "", "", "" };

static char *setup_strings;
module_param(setup_strings, charp, 0);

static void wd33c93_execute(struct Scsi_Host *instance);

#ifdef CONFIG_WD33C93_PIO
static inline uchar
read_wd33c93(const wd33c93_regs regs, uchar reg_num)
{
	uchar data;

	outb(reg_num, regs.SASR);
	data = inb(regs.SCMD);
	return data;
}

static inline unsigned long
read_wd33c93_count(const wd33c93_regs regs)
{
	unsigned long value;

	outb(WD_TRANSFER_COUNT_MSB, regs.SASR);
	value = inb(regs.SCMD) << 16;
	value |= inb(regs.SCMD) << 8;
	value |= inb(regs.SCMD);
	return value;
}

static inline uchar
read_aux_stat(const wd33c93_regs regs)
{
	return inb(regs.SASR);
}

static inline void
write_wd33c93(const wd33c93_regs regs, uchar reg_num, uchar value)
{
      outb(reg_num, regs.SASR);
      outb(value, regs.SCMD);
}

static inline void
write_wd33c93_count(const wd33c93_regs regs, unsigned long value)
{
	outb(WD_TRANSFER_COUNT_MSB, regs.SASR);
	outb((value >> 16) & 0xff, regs.SCMD);
	outb((value >> 8) & 0xff, regs.SCMD);
	outb( value & 0xff, regs.SCMD);
}

#define write_wd33c93_cmd(regs, cmd) \
	write_wd33c93((regs), WD_COMMAND, (cmd))

static inline void
write_wd33c93_cdb(const wd33c93_regs regs, uint len, uchar cmnd[])
{
	int i;

	outb(WD_CDB_1, regs.SASR);
	for (i=0; i<len; i++)
		outb(cmnd[i], regs.SCMD);
}

#else /* CONFIG_WD33C93_PIO */
static inline uchar
read_wd33c93(const wd33c93_regs regs, uchar reg_num)
{
	*regs.SASR = reg_num;
	mb();
	return (*regs.SCMD);
}

static unsigned long
read_wd33c93_count(const wd33c93_regs regs)
{
	unsigned long value;

	*regs.SASR = WD_TRANSFER_COUNT_MSB;
	mb();
	value = *regs.SCMD << 16;
	value |= *regs.SCMD << 8;
	value |= *regs.SCMD;
	mb();
	return value;
}

static inline uchar
read_aux_stat(const wd33c93_regs regs)
{
	return *regs.SASR;
}

static inline void
write_wd33c93(const wd33c93_regs regs, uchar reg_num, uchar value)
{
	*regs.SASR = reg_num;
	mb();
	*regs.SCMD = value;
	mb();
}

static void
write_wd33c93_count(const wd33c93_regs regs, unsigned long value)
{
	*regs.SASR = WD_TRANSFER_COUNT_MSB;
	mb();
	*regs.SCMD = value >> 16;
	*regs.SCMD = value >> 8;
	*regs.SCMD = value;
	mb();
}

static inline void
write_wd33c93_cmd(const wd33c93_regs regs, uchar cmd)
{
	*regs.SASR = WD_COMMAND;
	mb();
	*regs.SCMD = cmd;
	mb();
}

static inline void
write_wd33c93_cdb(const wd33c93_regs regs, uint len, uchar cmnd[])
{
	int i;

	*regs.SASR = WD_CDB_1;
	for (i = 0; i < len; i++)
		*regs.SCMD = cmnd[i];
}
#endif /* CONFIG_WD33C93_PIO */

static inline uchar
read_1_byte(const wd33c93_regs regs)
{
	uchar asr;
	uchar x = 0;

	write_wd33c93(regs, WD_CONTROL, CTRL_IDI | CTRL_EDI | CTRL_POLLED);
	write_wd33c93_cmd(regs, WD_CMD_TRANS_INFO | 0x80);
	do {
		asr = read_aux_stat(regs);
		if (asr & ASR_DBR)
			x = read_wd33c93(regs, WD_DATA);
	} while (!(asr & ASR_INT));
	return x;
}

static int
round_period(unsigned int period, const struct sx_period *sx_table)
{
	int x;

	for (x = 1; sx_table[x].period_ns; x++) {
		if ((period <= sx_table[x - 0].period_ns) &&
		    (period > sx_table[x - 1].period_ns)) {
			return x;
		}
	}
	return 7;
}

/*
 * Calculate Synchronous Transfer Register value from SDTR code.
 */
static uchar
calc_sync_xfer(unsigned int period, unsigned int offset, unsigned int fast,
               const struct sx_period *sx_table)
{
	/* When doing Fast SCSI synchronous data transfers, the corresponding
	 * value in 'sx_table' is two times the actually used transfer period.
	 */
	uchar result;

	if (offset && fast) {
		fast = STR_FSS;
		period *= 2;
	} else {
		fast = 0;
	}
	period *= 4;		/* convert SDTR code to ns */
	result = sx_table[round_period(period,sx_table)].reg_value;
	result |= (offset < OPTIMUM_SX_OFF) ? offset : OPTIMUM_SX_OFF;
	result |= fast;
	return result;
}

/*
 * Calculate SDTR code bytes [3],[4] from period and offset.
 */
static inline void
calc_sync_msg(unsigned int period, unsigned int offset, unsigned int fast,
                uchar  msg[2])
{
	/* 'period' is a "normal"-mode value, like the ones in 'sx_table'. The
	 * actually used transfer period for Fast SCSI synchronous data
	 * transfers is half that value.
	 */
	period /= 4;
	if (offset && fast)
		period /= 2;
	msg[0] = period;
	msg[1] = offset;
}

int
wd33c93_queuecommand(struct scsi_cmnd *cmd,
		void (*done)(struct scsi_cmnd *))
{
	struct WD33C93_hostdata *hostdata;
	struct scsi_cmnd *tmp;

	hostdata = (struct WD33C93_hostdata *) cmd->device->host->hostdata;

	DB(DB_QUEUE_COMMAND,
	   printk("Q-%d-%02x-%ld( ", cmd->device->id, cmd->cmnd[0], cmd->serial_number))

/* Set up a few fields in the scsi_cmnd structure for our own use:
 *  - host_scribble is the pointer to the next cmd in the input queue
 *  - scsi_done points to the routine we call when a cmd is finished
 *  - result is what you'd expect
 */
	cmd->host_scribble = NULL;
	cmd->scsi_done = done;
	cmd->result = 0;

/* We use the Scsi_Pointer structure that's included with each command
 * as a scratchpad (as it's intended to be used!). The handy thing about
 * the SCp.xxx fields is that they're always associated with a given
 * cmd, and are preserved across disconnect-reselect. This means we
 * can pretty much ignore SAVE_POINTERS and RESTORE_POINTERS messages
 * if we keep all the critical pointers and counters in SCp:
 *  - SCp.ptr is the pointer into the RAM buffer
 *  - SCp.this_residual is the size of that buffer
 *  - SCp.buffer points to the current scatter-gather buffer
 *  - SCp.buffers_residual tells us how many S.G. buffers there are
 *  - SCp.have_data_in is not used
 *  - SCp.sent_command is not used
 *  - SCp.phase records this command's SRCID_ER bit setting
 */

	if (cmd->use_sg) {
		cmd->SCp.buffer = (struct scatterlist *) cmd->request_buffer;
		cmd->SCp.buffers_residual = cmd->use_sg - 1;
		cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
		cmd->SCp.this_residual = cmd->SCp.buffer->length;
	} else {
		cmd->SCp.buffer = NULL;
		cmd->SCp.buffers_residual = 0;
		cmd->SCp.ptr = (char *) cmd->request_buffer;
		cmd->SCp.this_residual = cmd->request_bufflen;
	}

/* WD docs state that at the conclusion of a "LEVEL2" command, the
 * status byte can be retrieved from the LUN register. Apparently,
 * this is the case only for *uninterrupted* LEVEL2 commands! If
 * there are any unexpected phases entered, even if they are 100%
 * legal (different devices may choose to do things differently),
 * the LEVEL2 command sequence is exited. This often occurs prior
 * to receiving the status byte, in which case the driver does a
 * status phase interrupt and gets the status byte on its own.