/*
 *	ultrastor.c	Copyright (C) 1992 David B. Gentzel
 *	Low-level SCSI driver for UltraStor 14F, 24F, and 34F
 *	by David B. Gentzel, Whitfield Software Services, Carnegie, PA
 *	    (gentzel@nova.enet.dec.com)
 *  scatter/gather added by Scott Taylor (n217cg@tamuts.tamu.edu)
 *  24F and multiple command support by John F. Carr (jfc@athena.mit.edu)
 *    John's work modified by Caleb Epstein (cae@jpmorgan.com) and 
 *    Eric Youngdale (eric@tantalus.nrl.navy.mil).
 *	Thanks to UltraStor for providing the necessary documentation
 */

/*
 * TODO:
 *	1. Find out why scatter/gather is limited to 16 requests per command.
 *	2. Look at command linking (mscp.command_link and
 *	   mscp.command_link_id).  (Does not work with many disks, 
 *				and no performance increase.  ERY).
 *	3. Allow multiple adapters.
 */

/*
 * NOTES:
 *    The UltraStor 14F, 24F, and 34F are a family of intelligent, high
 *    performance SCSI-2 host adapters.  They all support command queueing
 *    and scatter/gather I/O.  Some of them can also emulate the standard
 *    WD1003 interface for use with OS's which don't support SCSI.  Here
 *    is the scoop on the various models:
 *	14F - ISA first-party DMA HA with floppy support and WD1003 emulation.
 *	14N - ISA HA with floppy support.  I think that this is a non-DMA
 *	      HA.  Nothing further known.
 *	24F - EISA Bus Master HA with floppy support and WD1003 emulation.
 *	34F - VL-Bus Bus Master HA with floppy support (no WD1003 emulation).
 *
 *    The 14F, 24F, and 34F are supported by this driver.
 *
 *    Places flagged with a triple question-mark are things which are either
 *    unfinished, questionable, or wrong.
 */

/* Changes from version 1.9 to 1.11
 *
 * Patches to bring this driver up to speed with the default kernel
 * driver which supports only the 14F and 34F adapters.  This version
 * should compile cleanly into 0.99.13, 0.99.12 and probably 0.99.11.
 *
 * Fixes from Eric Youngdale to fix a few possible race conditions and
 * several problems with bit testing operations (insufficient
 * parentheses).
 *
 * Removed the ultrastor_abort() and ultrastor_reset() functions
 * (enclosed them in #if 0 / #endif).  These functions, at least on
 * the 24F, cause the SCSI bus to do odd things and generally lead to
 * kernel panics and machine hangs.  This is like the Adaptec code.
 *
 * Use check/snarf_region for 14f, 34f to avoid I/O space address conflicts.
 */

/* Changes from version 1.8 to version 1.9
 *
 *  0.99.11 patches (cae@jpmorgan.com) */

/* Changes from version 1.7 to version 1.8
 *
 * Better error reporting.
 */

/* Changes from version 1.6 to version 1.7
 *
 * Removed CSIR command code.
 *
 * Better race condition avoidance (xchgb function added).
 *
 * Set ICM and OGM status to zero at probe (24F)
 *
 * reset sends soft reset to UltraStor adapter
 *
 * reset adapter if adapter interrupts with an invalid MSCP address
 *
 * handle aborted command interrupt (24F)
 *
 */

/* Changes from version 1.5 to version 1.6:
 *
 * Read MSCP address from ICM _before_ clearing the interrupt flag.
 * This fixes a race condition.
 */

/* Changes from version 1.4 to version 1.5:
 *
 * Abort now calls done when multiple commands are enabled.
 *
 * Clear busy when aborted command finishes, not when abort is called.
 *
 * More debugging messages for aborts.
 */

/* Changes from version 1.3 to version 1.4:
 *
 * Enable automatic request of sense data on error (requires newer version
 * of scsi.c to be useful).
 *
 * Fix PORT_OVERRIDE for 14F.
 *
 * Fix abort and reset to work properly (config.aborted wasn't cleared
 * after it was tested, so after a command abort no further commands would
 * work).
 *
 * Boot time test to enable SCSI bus reset (defaults to not allowing reset).
 *
 * Fix test for OGM busy -- the busy bit is in different places on the 24F.
 *
 * Release ICM slot by clearing first byte on 24F.
 */

#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/ioport.h>

#include <asm/io.h>
#include <asm/bitops.h>
#include <asm/system.h>
#include <asm/dma.h>

#define ULTRASTOR_PRIVATE	/* Get the private stuff from ultrastor.h */
#include "../block/blk.h"
#include "scsi.h"
#include "hosts.h"
#include "ultrastor.h"

#define FALSE 0
#define TRUE 1

#ifndef ULTRASTOR_DEBUG
#define ULTRASTOR_DEBUG (UD_ABORT|UD_CSIR|UD_RESET)
#endif

#define VERSION "1.11 alpha"

#define ARRAY_SIZE(arr) (sizeof (arr) / sizeof (arr)[0])

#define PACKED		__attribute__((packed))
#define ALIGNED(x)	__attribute__((aligned(x)))


/* The 14F uses an array of 4-byte ints for its scatter/gather list.
   The data can be unaligned, but need not be.  It's easier to give
   the list normal alignment since it doesn't need to fit into a
   packed structure.  */

typedef struct {
  unsigned int address;
  unsigned int num_bytes;
} ultrastor_sg_list;


/* MailBox SCSI Command Packet.  Basic command structure for communicating
   with controller. */
struct mscp {
  unsigned char opcode: 3;		/* type of command */
  unsigned char xdir: 2;		/* data transfer direction */
  unsigned char dcn: 1;		/* disable disconnect */
  unsigned char ca: 1;		/* use cache (if available) */
  unsigned char sg: 1;		/* scatter/gather operation */
  unsigned char target_id: 3;		/* target SCSI id */
  unsigned char ch_no: 2;		/* SCSI channel (always 0 for 14f) */
  unsigned char lun: 3;		/* logical unit number */
  unsigned int transfer_data PACKED;	/* transfer data pointer */
  unsigned int transfer_data_length PACKED;	/* length in bytes */
  unsigned int command_link PACKED;	/* for linking command chains */
  unsigned char scsi_command_link_id;	/* identifies command in chain */
  unsigned char number_of_sg_list;	/* (if sg is set) 8 bytes per list */
  unsigned char length_of_sense_byte;
  unsigned char length_of_scsi_cdbs;	/* 6, 10, or 12 */
  unsigned char scsi_cdbs[12];	/* SCSI commands */
  unsigned char adapter_status;	/* non-zero indicates HA error */
  unsigned char target_status;	/* non-zero indicates target error */
  unsigned int sense_data PACKED;
  /* The following fields are for software only.  They are included in
     the MSCP structure because they are associated with SCSI requests.  */
  void (*done)(Scsi_Cmnd *);
  Scsi_Cmnd *SCint;
  ultrastor_sg_list sglist[ULTRASTOR_14F_MAX_SG];
};


/* Port addresses (relative to the base address) */
#define U14F_PRODUCT_ID(port) ((port) + 0x4)
#define CONFIG(port) ((port) + 0x6)

/* Port addresses relative to the doorbell base address.  */
#define LCL_DOORBELL_MASK(port) ((port) + 0x0)
#define LCL_DOORBELL_INTR(port) ((port) + 0x1)
#define SYS_DOORBELL_MASK(port) ((port) + 0x2)
#define SYS_DOORBELL_INTR(port) ((port) + 0x3)


/* Used to store configuration info read from config i/o registers.  Most of
   this is not used yet, but might as well save it.
   
   This structure also holds port addresses that are not at the same offset
   on the 14F and 24F.
   
   This structure holds all data that must be duplicated to support multiple
   adapters.  */

static struct ultrastor_config
{
  unsigned short port_address;		/* base address of card */
  unsigned short doorbell_address;	/* base address of doorbell CSRs */
  unsigned short ogm_address;		/* base address of OGM */
  unsigned short icm_address;		/* base address of ICM */
  const void *bios_segment;
  unsigned char interrupt: 4;
  unsigned char dma_channel: 3;
  unsigned char bios_drive_number: 1;
  unsigned char heads;
  unsigned char sectors;
  unsigned char ha_scsi_id: 3;
  unsigned char subversion: 4;
  unsigned char revision;
  /* The slot number is used to distinguish the 24F (slot != 0) from
     the 14F and 34F (slot == 0). */
  unsigned char slot;

#ifdef PRINT_U24F_VERSION
  volatile int csir_done;
#endif

  /* Our index in the host adapter array maintained by higher-level driver */
  int host_number;

  /* A pool of MSCP structures for this adapter, and a bitmask of
     busy structures.  (If ULTRASTOR_14F_MAX_CMDS == 1, a 1 byte
     busy flag is used instead.)  */

#if ULTRASTOR_MAX_CMDS == 1
  unsigned char mscp_busy;
#else
  unsigned short mscp_free;
#endif
  volatile unsigned char aborted[ULTRASTOR_MAX_CMDS];
  struct mscp mscp[ULTRASTOR_MAX_CMDS];
} config = {0};

/* Set this to 1 to reset the SCSI bus on error.  */
int ultrastor_bus_reset = 0;


/* Allowed BIOS base addresses (NULL indicates reserved) */
static const void *const bios_segment_table[8] = {
  NULL,	     (void *)0xC4000, (void *)0xC8000, (void *)0xCC000,
  (void *)0xD0000, (void *)0xD4000, (void *)0xD8000, (void *)0xDC000,
};

/* Allowed IRQs for 14f */
static const unsigned char interrupt_table_14f[4] = { 15, 14, 11, 10 };

/* Allowed DMA channels for 14f (0 indicates reserved) */
static const unsigned char dma_channel_table_14f[4] = { 5, 6, 7, 0 };

/* Head/sector mappings allowed by 14f */
static const struct {
  unsigned char heads;
  unsigned char sectors;
} mapping_table[4] = { { 16, 63 }, { 64, 32 }, { 64, 63 }, { 64, 32 } };

#ifndef PORT_OVERRIDE
/* ??? A probe of address 0x310 screws up NE2000 cards */
static const unsigned short ultrastor_ports_14f[] = {
  0x330, 0x340, /*0x310,*/ 0x230, 0x240, 0x210, 0x130, 0x140,
};
#endif

static void ultrastor_interrupt(int cpl);
static inline void build_sg_list(struct mscp *, Scsi_Cmnd *SCpnt);


static inline int find_and_clear_bit_16(unsigned short *field)
{
  int rv;
  cli();
  if (*field == 0) panic("No free mscp");
  asm("xorl %0,%0\n0:\tbsfw %1,%w0\n\tbtr %0,%1\n\tjnc 0b"
      : "=&r" (rv), "=m" (*field) : "1" (*field));
  sti();
  return rv;
}

/* This asm is fragile: it doesn't work without the casts and it may
   not work without optimization.  Maybe I should add a swap builtin
   to gcc.  --jfc  */
static inline unsigned char xchgb(unsigned char reg,
				  volatile unsigned char *mem)
{
  asm("xchgb %0,%1" :
      "=r" (reg), "=m" (*(unsigned char *)mem) :
      "0" (reg), "1" (*(unsigned char *)mem));
  return reg;
}

#if ULTRASTOR_DEBUG & (UD_COMMAND | UD_ABORT)

static void log_ultrastor_abort(register struct ultrastor_config *config,
				int command)
{
  static char fmt[80] = "abort %d (%x); MSCP free pool: %x;";
  register int i;
  int flags;
  save_flags(flags);
  cli();

  for (i = 0; i < ULTRASTOR_MAX_CMDS; i++)
    {
      fmt[20 + i*2] = ' ';
      if (! (config->mscp_free & (1 << i)))
	fmt[21 + i*2] = '0' + config->mscp[i].target_id;
      else
	fmt[21 + i*2] = '-';
    }
  fmt[20 + ULTRASTOR_MAX_CMDS * 2] = '\n';
  fmt[21 + ULTRASTOR_MAX_CMDS * 2] = 0;
  printk(fmt, command, &config->mscp[command], config->mscp_free);
  restore_flags(flags);
}
#endif

static int ultrastor_14f_detect(int hostnum)
{
    size_t i;
    unsigned char in_byte, version_byte = 0;
    struct config_1 {
      unsigned char bios_segment: 3;
      unsigned char removable_disks_as_fixed: 1;
      unsigned char interrupt: 2;
    unsigned char dma_channel: 2;
    } config_1;
    struct config_2 {
      unsigned char ha_scsi_id: 3;
      unsigned char mapping_mode: 2;
      unsigned char bios_drive_number: 1;
      unsigned char tfr_port: 2;
    } config_2;

#if (ULTRASTOR_DEBUG & UD_DETECT)
    printk("US14F: detect: called\n");
#endif

    /* If a 24F has already been configured, don't look for a 14F.  */
    if (config.bios_segment)
	return FALSE;

#ifdef PORT_OVERRIDE
    if(check_region(PORT_OVERRIDE, 0xc)) {
      printk("Ultrastor I/O space already in use\n");
      return FALSE;
    };
    config.port_address = PORT_OVERRIDE;
#else
    for (i = 0; i < ARRAY_SIZE(ultrastor_ports_14f); i++) {
      if(check_region(ultrastor_ports_14f[i], 0x0c)) continue;
      config.port_address = ultrastor_ports_14f[i];
#endif

#if (ULTRASTOR_DEBUG & UD_DETECT)
	printk("US14F: detect: testing port address %03X\n", config.port_address);
#endif