/* $Id: wd7000.c,v 1.2 1994/01/15 06:02:32 drew Exp $
 *  linux/kernel/wd7000.c
 *
 *  Copyright (C) 1992  Thomas Wuensche
 *	closely related to the aha1542 driver from Tommy Thorn
 *	( as close as different hardware allows on a lowlevel-driver :-) )
 *
 *  Revised (and renamed) by John Boyd <boyd@cis.ohio-state.edu> to
 *  accomodate Eric Youngdale's modifications to scsi.c.  Nov 1992.
 *
 *  Additional changes to support scatter/gather.  Dec. 1992.  tw/jb
 */

#include <stdarg.h>
#include <linux/kernel.h>
#include <linux/head.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <asm/system.h>
#include <asm/dma.h>
#include <asm/io.h>
#include <linux/ioport.h>

#include "../block/blk.h"
#include "scsi.h"
#include "hosts.h"

/* #define DEBUG  */

#include "wd7000.h"


#ifdef DEBUG
#define DEB(x) x
#else
#define DEB(x)
#endif


/*
   Driver data structures:
   - mb and scbs are required for interfacing with the host adapter.
     An SCB has extra fields not visible to the adapter; mb's
     _cannot_ do this, since the adapter assumes they are contiguous in
     memory, 4 bytes each, with ICMBs following OGMBs, and uses this fact
     to access them.
   - An icb is for host-only (non-SCSI) commands.  ICBs are 16 bytes each;
     the additional bytes are used only by the driver.
   - For now, a pool of SCBs are kept in global storage by this driver,
     and are allocated and freed as needed.

  The 7000-FASST2 marks OGMBs empty as soon as it has _started_ a command,
  not when it has finished.  Since the SCB must be around for completion,
  problems arise when SCBs correspond to OGMBs, which may be reallocated
  earlier (or delayed unnecessarily until a command completes).
  Mailboxes are used as transient data structures, simply for
  carrying SCB addresses to/from the 7000-FASST2.

  Note also since SCBs are not "permanently" associated with mailboxes,
  there is no need to keep a global list of Scsi_Cmnd pointers indexed
  by OGMB.   Again, SCBs reference their Scsi_Cmnds directly, so mailbox
  indices need not be involved.
*/

static struct {
       struct wd_mailbox ogmb[OGMB_CNT]; 
       struct wd_mailbox icmb[ICMB_CNT];
} mb;
static int next_ogmb = 0;   /* to reduce contention at mailboxes */

static Scb scbs[MAX_SCBS];
static Scb *scbfree = NULL;

static int wd7000_host = 0;
static unchar controlstat = 0;

static unchar rev_1 = 0, rev_2 = 0;  /* filled in by wd7000_revision */

#define wd7000_intr_ack()  outb(0,INTR_ACK)

#define WAITnexttimeout 3000000


static inline void wd7000_enable_intr(void)
{
    controlstat |= INT_EN;
    outb(controlstat,CONTROL);
}


static inline void wd7000_enable_dma(void)
{
    controlstat |= DMA_EN;
    outb(controlstat,CONTROL);
    set_dma_mode(DMA_CH, DMA_MODE_CASCADE);
    enable_dma(DMA_CH);
}


#define WAIT(port, mask, allof, noneof)					\
 { register WAITbits;							\
   register WAITtimeout = WAITnexttimeout;				\
   while (1) {								\
     WAITbits = inb(port) & (mask);					\
     if ((WAITbits & (allof)) == (allof) && ((WAITbits & (noneof)) == 0)) \
       break;                                                         	\
     if (--WAITtimeout == 0) goto fail;					\
   }									\
 }


static inline void delay( unsigned how_long )
{
     unsigned long time = jiffies + how_long;

     while (jiffies < time);
}


static inline int command_out(unchar *cmdp, int len)
{
    while (len--)  {
        WAIT(ASC_STAT, STATMASK, CMD_RDY, 0);
	outb(*cmdp++, COMMAND);
    }
    return 1;

fail:
    printk("wd7000_out WAIT failed(%d): ", len+1);
    return 0;
}

static inline Scb *alloc_scb(void)
{
    Scb *scb;
    unsigned long flags;

    save_flags(flags);
    cli();

    if (scbfree == NULL)  {
        panic("wd7000: can't allocate free SCB.\n");
	restore_flags(flags);
	return NULL;
    }
    scb = scbfree;  scbfree = scb->next;
    memset(scb, 0, sizeof(Scb));  scb->next = NULL;

    restore_flags(flags);

    return scb;
}


static inline void free_scb( Scb *scb )
{
    unsigned long flags;

    save_flags(flags);
    cli();

    memset(scb, 0, sizeof(Scb));
    scb->next = scbfree;  scbfree = scb;

    restore_flags(flags);
}


static inline void init_scbs(void)
{
    int i;
    unsigned long flags;

    save_flags(flags);
    cli();

    scbfree = &(scbs[0]);
    for (i = 0;  i < MAX_SCBS-1;  i++)  scbs[i].next = &(scbs[i+1]);
    scbs[MAX_SCBS-1].next = NULL;

    restore_flags(flags);
}    
    

static int mail_out( Scb *scbptr )
/*
 *  Note: this can also be used for ICBs; just cast to the parm type.
 */
{
    int i, ogmb;
    unsigned long flags;

    DEB(printk("wd7000_scb_out: %06x");)

    /* We first look for a free outgoing mailbox */
    save_flags(flags);
    cli();
    ogmb = next_ogmb;
    for (i = 0; i < OGMB_CNT; i++) {
	if (mb.ogmb[ogmb].status == 0)  {
	    DEB(printk(" using OGMB %x",ogmb));
	    mb.ogmb[ogmb].status = 1;
	    any2scsi(mb.ogmb[ogmb].scbptr, scbptr);

	    next_ogmb = (ogmb+1) % OGMB_CNT;
	    break;
	}  else
	    ogmb = (++ogmb) % OGMB_CNT;
    }
    restore_flags(flags);
    DEB(printk(", scb is %x",scbptr);)

    if (i >= OGMB_CNT) {
        DEB(printk(", no free OGMBs.\n");)
	/* Alternatively, issue "interrupt on free OGMB", and sleep... */
        return 0;
    }

    wd7000_enable_intr(); 
    do  {
        WAIT(ASC_STAT,STATMASK,CMD_RDY,0);
	outb(START_OGMB|ogmb, COMMAND);
	WAIT(ASC_STAT,STATMASK,CMD_RDY,0);
    }  while (inb(ASC_STAT) & CMD_REJ);

    DEB(printk(", awaiting interrupt.\n");)
    return 1;

fail:
    DEB(printk(", WAIT timed out.\n");)
    return 0;
}


int make_code(unsigned hosterr, unsigned scsierr)
{   
#ifdef DEBUG
    int in_error = hosterr;
#endif

    switch ((hosterr>>8)&0xff){
	case 0:	/* Reserved */
		hosterr = DID_ERROR;
		break;
	case 1:	/* Command Complete, no errors */
		hosterr = DID_OK;
		break;
	case 2: /* Command complete, error logged in scb status (scsierr) */ 
		hosterr = DID_OK;
		break;
	case 4:	/* Command failed to complete - timeout */
		hosterr = DID_TIME_OUT;
		break;
	case 5:	/* Command terminated; Bus reset by external device */
		hosterr = DID_RESET;
		break;
	case 6:	/* Unexpected Command Received w/ host as target */
		hosterr = DID_BAD_TARGET;
		break;
	case 80: /* Unexpected Reselection */
        case 81: /* Unexpected Selection */
		hosterr = DID_BAD_INTR;
		break;
        case 82: /* Abort Command Message  */
		hosterr = DID_ABORT;
		break;
	case 83: /* SCSI Bus Software Reset */
	case 84: /* SCSI Bus Hardware Reset */
		hosterr = DID_RESET;
		break;
        default: /* Reserved */
		hosterr = DID_ERROR;
		break;
	}
#ifdef DEBUG
    if (scsierr||hosterr)
        printk("\nSCSI command error: SCSI %02x host %04x return %d",
	       scsierr,in_error,hosterr);
#endif
    return scsierr | (hosterr << 16);
}


static void wd7000_scsi_done(Scsi_Cmnd * SCpnt)
{
    DEB(printk("wd7000_scsi_done: %06x\n",SCpnt);)
    SCpnt->SCp.phase = 0;
}


void wd7000_intr_handle(int irq)
{
    int flag, icmb, errstatus, icmb_status;
    int host_error, scsi_error;
    Scb *scb;             /* for SCSI commands */
    unchar *icb;          /* for host commands */
    Scsi_Cmnd *SCpnt;

    flag = inb(INTR_STAT);
    DEB(printk("wd7000_intr_handle: intr stat = %02x",flag);)

    if (!(inb(ASC_STAT)&0x80)){ 
	DEB(printk("\nwd7000_intr_handle: phantom interrupt...\n");)
	wd7000_intr_ack();
	return; 
    }

    /* check for an incoming mailbox */
    if ((flag & 0x40) == 0) {
        /*  for a free OGMB - need code for this case... */
        DEB(printk("wd7000_intr_handle: free outgoing mailbox\n");)