in2000.c

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/*
 *    in2000.c -  Linux device driver for the
 *                Always IN2000 ISA SCSI 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 provided
 * much of the inspiration and some of the code for this driver.
 * The Linux IN2000 driver distributed in the Linux kernels through
 * version 1.2.13 was an extremely valuable reference on the arcane
 * (and still mysterious) workings of the IN2000's fifo. It also
 * is where I lifted in2000_biosparam(), the gist of the card
 * detection scheme, and other bits of code. Many thanks to the
 * talented and courageous people who wrote, contributed to, and
 * maintained that driver (including Brad McLean, Shaun Savage,
 * Bill Earnest, Larry Doolittle, Roger Sunshine, John Luckey,
 * Matt Postiff, Peter Lu, [e-mail], and Eric
 * Youngdale). I should also mention the driver written by
 * Hamish Macdonald for the (GASP!) Amiga A2091 card, included
 * in the Linux-m68k distribution; it gave me a good initial
 * understanding of the proper way to run a WD33c93 chip, and I
 * ended up stealing lots of code from it.
 *
 * _This_ driver is (I feel) an improvement over the old one in
 * several respects:
 *    -  All problems relating to the data size of a SCSI request are
 *          gone (as far as I know). The old driver couldn't handle
 *          swapping to partitions because that involved 4k blocks, nor
 *          could it deal with the st.c tape driver unmodified, because
 *          that usually involved 4k - 32k blocks. The old driver never
 *          quite got away from a morbid dependence on 2k block sizes -
 *          which of course is the size of the card's fifo.
 *
 *    -  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'm
 *          calling '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 there
 *          are a few devices (and many improperly terminated systems)
 *          that choke when doing sync, the default is sync DISABLED
 *          for all devices. This faster protocol can (and should!)
 *          be enabled on selected devices via the command-line.
 *
 *    -  Runtime operating parameters can now be specified through
 *       either the LILO or the 'insmod' command line. For LILO do:
 *          "in2000=blah,blah,blah"
 *       and with insmod go like:
 *          "insmod /usr/src/linux/modules/in2000.o setup_strings=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.
 *
 *    -  You can force detection of a card whose BIOS has been disabled.
 *
 *    -  Multiple IN2000 cards might almost be supported. I've tried to
 *       keep it in mind, but have no way to test...
 *
 *
 * TODO:
 *       tagged queuing. multiple cards.
 *
 *
 * NOTE:
 *       When using this or any other SCSI driver as a module, you'll
 *       find that with the stock kernel, at most _two_ SCSI hard
 *       drives will be linked into the device list (ie, usable).
 *       If your IN2000 card has more than 2 disks on its bus, you
 *       might want to change the define of 'SD_EXTRA_DEVS' in the
 *       'hosts.h' file from 2 to whatever is appropriate. It took
 *       me a while to track down this surprisingly obscure and
 *       undocumented little "feature".
 *
 *
 * 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".
 *
 */

#include <linux/module.h>

#include <asm/system.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/proc_fs.h>
#include <asm/io.h>
#include <linux/ioport.h>
#include <linux/blkdev.h>

#include <linux/blk.h>
#include <linux/stat.h>

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

#define IN2000_VERSION    "1.33"
#define IN2000_DATE       "26/August/1998"

#include "in2000.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 a LILO or insmod command-line, those
 * settings are combined with 'setup_args[]'. Note that LILO command-lines
 * are prefixed with "in2000=" while insmod uses a "setup_strings=" prefix.
 * The driver recognizes the following keywords (lower case required) and
 * arguments:
 *
 * -  ioport:addr    -Where addr is IO address of a (usually ROM-less) card.
 * -  noreset        -No optional args. Prevents SCSI bus reset at boot time.
 * -  nosync:x       -x is a bitmask where the 1st 7 bits correspond with
 *                    the 7 possible SCSI devices (bit 0 for device #0, etc).
 *                    Set a bit to PREVENT sync negotiation on that device.
 *                    The driver default is sync DISABLED on all devices.
 * -  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 bitmask that causes
 *                    various types of debug output to printed - see the DB_xxx
 *                    defines in in2000.h
 * -  proc:x         -If 'PROC_INTERFACE' is defined, x is a bitmask that
 *                    determines how the /proc interface works and what it
 *                    does - see the PR_xxx defines in in2000.h
 *
 * 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.
 *
 * A few LILO examples (for insmod, use 'setup_strings' instead of 'in2000'):
 * -  in2000=ioport:0x220,noreset
 * -  in2000=period:250,disconnect:2,nosync:0x03
 * -  in2000=debug:0x1e
 * -  in2000=proc:3
 */

/* 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 struct Scsi_Host *instance_list = 0;



static inline uchar read_3393(struct IN2000_hostdata *hostdata, uchar reg_num)
{
   write1_io(reg_num,IO_WD_ADDR);
   return read1_io(IO_WD_DATA);
}


#define READ_AUX_STAT() read1_io(IO_WD_ASR)


static inline void write_3393(struct IN2000_hostdata *hostdata, uchar reg_num, uchar value)
{
   write1_io(reg_num,IO_WD_ADDR);
   write1_io(value,IO_WD_DATA);
}


static inline void write_3393_cmd(struct IN2000_hostdata *hostdata, uchar cmd)
{
/*   while (READ_AUX_STAT() & ASR_CIP)
      printk("|");*/
   write1_io(WD_COMMAND,IO_WD_ADDR);
   write1_io(cmd,IO_WD_DATA);
}


static uchar read_1_byte(struct IN2000_hostdata *hostdata)
{
uchar asr, x = 0;

   write_3393(hostdata,WD_CONTROL, CTRL_IDI | CTRL_EDI | CTRL_POLLED);
   write_3393_cmd(hostdata,WD_CMD_TRANS_INFO|0x80);
   do {
      asr = READ_AUX_STAT();
      if (asr & ASR_DBR)
         x = read_3393(hostdata,WD_DATA);
      } while (!(asr & ASR_INT));
   return x;
}


static void write_3393_count(struct IN2000_hostdata *hostdata, unsigned long value)
{
   write1_io(WD_TRANSFER_COUNT_MSB,IO_WD_ADDR);
   write1_io((value >> 16),IO_WD_DATA);
   write1_io((value >> 8),IO_WD_DATA);
   write1_io(value,IO_WD_DATA);
}


static unsigned long read_3393_count(struct IN2000_hostdata *hostdata)
{
unsigned long value;

   write1_io(WD_TRANSFER_COUNT_MSB,IO_WD_ADDR);
   value = read1_io(IO_WD_DATA) << 16;
   value |= read1_io(IO_WD_DATA) << 8;
   value |= read1_io(IO_WD_DATA);
   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 in2000_execute(struct Scsi_Host *instance);

int in2000_queuecommand (Scsi_Cmnd *cmd, void (*done)(Scsi_Cmnd *))
{
struct IN2000_hostdata *hostdata;
Scsi_Cmnd *tmp;
unsigned long flags;

   hostdata = (struct IN2000_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 helps keep track of >2048 byte transfers
 *  - 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;
      }
   cmd->SCp.have_data_in = 0;

/* We don't set SCp.phase here - that's done in in2000_execute() */

/* 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