wd33c93.c

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/*
 *    wd33c93.c - Linux-68k device driver for the Commodore
 *                Amiga A2091/590 SCSI controller card
 *
 * 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
 */

#include <linux/config.h>
#include <linux/module.h>

#include <asm/system.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/version.h>
#include <linux/init.h>
#include <asm/irq.h>
#include <linux/blk.h>

#include "scsi.h"
#include "hosts.h"


#define WD33C93_VERSION    "1.25"
#define WD33C93_DATE       "09/Jul/1997"
/* NOTE: 1.25 for m68k is related to in2000-1.31 for x86 */

/*
 * Note - the following defines have been moved to 'wd33c93.h':
 *
 *    PROC_INTERFACE
 *    PROC_STATISTICS
 *    SYNC_DEBUG
 *    DEBUGGING_ON
 *    DEBUG_DEFAULTS
 *
 */


#include "wd33c93.h"



/*
 * '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.
 * -  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[] =
      {"","","","","","","","",""};

/* filled in by 'insmod' */
static char *setup_strings = 0;

#ifdef MODULE_PARM
MODULE_PARM(setup_strings, "s");
#endif



static inline uchar read_wd33c93(wd33c93_regs *regp,uchar reg_num)
{
   regp->SASR = reg_num;
   mb();
   return(regp->SCMD);
}


#define READ_AUX_STAT() (regp->SASR)


static inline void write_wd33c93(wd33c93_regs *regp,uchar reg_num, uchar value)
{
   regp->SASR = reg_num;
   mb();
   regp->SCMD = value;
   mb();
}


static inline void write_wd33c93_cmd(wd33c93_regs *regp, uchar cmd)
{
   regp->SASR = WD_COMMAND;
   mb();
   regp->SCMD = cmd;
   mb();
}


static inline uchar read_1_byte(wd33c93_regs *regp)
{
uchar asr;
uchar x = 0;

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


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


static unsigned long read_wd33c93_count(wd33c93_regs *regp)
{
unsigned long value;

   regp->SASR = WD_TRANSFER_COUNT_MSB;
   mb();
   value = regp->SCMD << 16;
   value |= regp->SCMD << 8;
   value |= regp->SCMD;
   mb();
   return value;
}


/* The 33c93 needs to be told which direction a command transfers its
 * data; we use this function to figure it out. Returns true if there
 * will be a DATA_OUT phase with this command, false otherwise.
 * (Thanks to Joerg Dorchain for the research and suggestion.)
 */
static int is_dir_out(Scsi_Cmnd *cmd)
{
   switch (cmd->cmnd[0]) {
      case WRITE_6:           case WRITE_10:          case WRITE_12:
      case WRITE_LONG:        case WRITE_SAME:        case WRITE_BUFFER:
      case WRITE_VERIFY:      case WRITE_VERIFY_12:      
      case COMPARE:           case COPY:              case COPY_VERIFY:
      case SEARCH_EQUAL:      case SEARCH_HIGH:       case SEARCH_LOW:
      case SEARCH_EQUAL_12:   case SEARCH_HIGH_12:    case SEARCH_LOW_12:      
      case FORMAT_UNIT:       case REASSIGN_BLOCKS:   case RESERVE:
      case MODE_SELECT:       case MODE_SELECT_10:    case LOG_SELECT:
      case SEND_DIAGNOSTIC:   case CHANGE_DEFINITION: case UPDATE_BLOCK:
      case SET_WINDOW:        case MEDIUM_SCAN:       case SEND_VOLUME_TAG:
      case 0xea:
         return 1;
      default:
         return 0;
      }
}



static struct sx_period sx_table[] = {
   {  1, 0x20},
   {252, 0x20},
   {376, 0x30},
   {500, 0x40},
   {624, 0x50},
   {752, 0x60},
   {876, 0x70},
   {1000,0x00},
   {0,   0} };

static int round_period(unsigned int period)
{
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;
}

static uchar calc_sync_xfer(unsigned int period, unsigned int offset)
{
uchar result;

   period *= 4;   /* convert SDTR code to ns */
   result = sx_table[round_period(period)].reg_value;
   result |= (offset < OPTIMUM_SX_OFF)?offset:OPTIMUM_SX_OFF;
   return result;
}



static void wd33c93_execute(struct Scsi_Host *instance);

int wd33c93_queuecommand (Scsi_Cmnd *cmd, void (*done)(Scsi_Cmnd *))
{
   struct WD33C93_hostdata *hostdata;
   Scsi_Cmnd *tmp;
   unsigned long flags;

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

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

/* 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->buffer;
      cmd->SCp.buffers_residual = cmd->use_sg - 1;
      cmd->SCp.ptr = (char *)cmd->SCp.buffer->address;
      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.
 * While such a command can then be "resumed" (ie restarted to
 * finish up as a LEVEL2 command), the LUN register will NOT be
 * a valid status byte at the command's conclusion, and we must
 * use the byte obtained during the earlier interrupt. Here, we
 * preset SCp.Status to an illegal value (0xff) so that when
 * this command finally completes, we can tell where the actual
 * status byte is stored.
 */

   cmd->SCp.Status = ILLEGAL_STATUS_BYTE;

   /*
    * Add the cmd to the end of 'input_Q'. Note that REQUEST SENSE
    * commands are added to the head of the queue so that the desired
    * sense data is not lost before REQUEST_SENSE executes.
    */

   save_flags(flags);
   cli();

   if (!(hostdata->input_Q) || (cmd->cmnd[0] == REQUEST_SENSE)) {
      cmd->host_scribble = (uchar *)hostdata->input_Q;
      hostdata->input_Q = cmd;
      }
   else {   /* find the end of the queue */
      for (tmp=(Scsi_Cmnd *)hostdata->input_Q; tmp->host_scribble;
            tmp=(Scsi_Cmnd *)tmp->host_scribble)
         ;
      tmp->host_scribble = (uchar *)cmd;
      }

/* We know that there's at least one command in 'input_Q' now.
 * Go see if any of them are runnable!
 */