ppa.c

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    w_dtr(ppb, (1 << target));
    w_ctr(ppb, 0xe);
    w_ctr(ppb, 0xc);
    w_dtr(ppb, 0x80);		/* This is NOT the initator */
    w_ctr(ppb, 0x8);

    k = PPA_SELECT_TMO;
    do {
	k--;
	udelay(1);
    }
    while (!(r_str(ppb) & 0x40) && (k));
    if (!k)
	return 0;

    return 1;
}

/* 
 * This is based on a trace of what the Iomega DOS 'guest' driver does.
 * I've tried several different kinds of parallel ports with guest and
 * coded this to react in the same ways that it does.
 * 
 * The return value from this function is just a hint about where the
 * handshaking failed.
 * 
 */
static int ppa_init(int host_no)
{
    int retv;
    unsigned short ppb = PPA_BASE(host_no);

#if defined(CONFIG_PARPORT) || defined(CONFIG_PARPORT_MODULE)
    if (ppa_pb_claim(host_no))
	while (ppa_hosts[host_no].p_busy)
	    schedule();		/* We can safe schedule here */
#endif

    ppa_disconnect(host_no);
    ppa_connect(host_no, CONNECT_NORMAL);

    retv = 2;			/* Failed */

    w_ctr(ppb, 0xe);
    if ((r_str(ppb) & 0x08) == 0x08)
	retv--;

    w_ctr(ppb, 0xc);
    if ((r_str(ppb) & 0x08) == 0x00)
	retv--;

    if (!retv)
	ppa_reset_pulse(ppb);
    udelay(1000);		/* Allow devices to settle down */
    ppa_disconnect(host_no);
    udelay(1000);		/* Another delay to allow devices to settle */

    if (!retv)
	retv = device_check(host_no);

    ppa_pb_release(host_no);
    return retv;
}

static inline int ppa_send_command(Scsi_Cmnd * cmd)
{
    int host_no = cmd->host->unique_id;
    int k;

    w_ctr(PPA_BASE(host_no), 0x0c);

    for (k = 0; k < cmd->cmd_len; k++)
	if (!ppa_out(host_no, &cmd->cmnd[k], 1))
	    return 0;
    return 1;
}

/*
 * The bulk flag enables some optimisations in the data transfer loops,
 * it should be true for any command that transfers data in integral
 * numbers of sectors.
 * 
 * The driver appears to remain stable if we speed up the parallel port
 * i/o in this function, but not elsewhere.
 */
static int ppa_completion(Scsi_Cmnd * cmd)
{
    /* Return codes:
     * -1     Error
     *  0     Told to schedule
     *  1     Finished data transfer
     */
    int host_no = cmd->host->unique_id;
    unsigned short ppb = PPA_BASE(host_no);
    unsigned long start_jiffies = jiffies;

    unsigned char r, v;
    int fast, bulk, status;

    v = cmd->cmnd[0];
    bulk = ((v == READ_6) ||
	    (v == READ_10) ||
	    (v == WRITE_6) ||
	    (v == WRITE_10));

    /*
     * We only get here if the drive is ready to comunicate,
     * hence no need for a full ppa_wait.
     */
    r = (r_str(ppb) & 0xf0);

    while (r != (unsigned char) 0xf0) {
	/*
	 * If we have been running for more than a full timer tick
	 * then take a rest.
	 */
	if (time_after(jiffies, start_jiffies + 1))
	    return 0;

	if ((cmd->SCp.this_residual <= 0)) {
	    ppa_fail(host_no, DID_ERROR);
	    return -1;		/* ERROR_RETURN */
	}

	/* On some hardware we have SCSI disconnected (6th bit low)
	 * for about 100usecs. It is too expensive to wait a 
	 * tick on every loop so we busy wait for no more than
	 * 500usecs to give the drive a chance first. We do not 
	 * change things for "normal" hardware since generally 
	 * the 6th bit is always high.
	 * This makes the CPU load higher on some hardware 
	 * but otherwise we can not get more then 50K/secs 
	 * on this problem hardware.
	 */
	if ((r & 0xc0) != 0xc0) {
	   /* Wait for reconnection should be no more than 
	    * jiffy/2 = 5ms = 5000 loops
	    */
	   unsigned long k = ppa_hosts[host_no].recon_tmo; 
	   for (; k && ((r = (r_str(ppb) & 0xf0)) & 0xc0) != 0xc0; k--)
	     udelay(1);

	   if(!k) 
	     return 0;
	}	   

	/* determine if we should use burst I/O */ 
	fast = (bulk && (cmd->SCp.this_residual >= PPA_BURST_SIZE)) 
	     ? PPA_BURST_SIZE : 1;

	if (r == (unsigned char) 0xc0)
	    status = ppa_out(host_no, cmd->SCp.ptr, fast);
	else
	    status = ppa_in(host_no, cmd->SCp.ptr, fast);

	cmd->SCp.ptr += fast;
	cmd->SCp.this_residual -= fast;

	if (!status) {
	    ppa_fail(host_no, DID_BUS_BUSY);
	    return -1;		/* ERROR_RETURN */
	}
	if (cmd->SCp.buffer && !cmd->SCp.this_residual) {
	    /* if scatter/gather, advance to the next segment */
	    if (cmd->SCp.buffers_residual--) {
		cmd->SCp.buffer++;
		cmd->SCp.this_residual = cmd->SCp.buffer->length;
		cmd->SCp.ptr = cmd->SCp.buffer->address;
	    }
	}
	/* Now check to see if the drive is ready to comunicate */
	r = (r_str(ppb) & 0xf0);
	/* If not, drop back down to the scheduler and wait a timer tick */
	if (!(r & 0x80))
	    return 0;
    }
    return 1;			/* FINISH_RETURN */
}

/* deprecated synchronous interface */
int ppa_command(Scsi_Cmnd * cmd)
{
    static int first_pass = 1;
    int host_no = cmd->host->unique_id;

    if (first_pass) {
	printk("ppa: using non-queuing interface\n");
	first_pass = 0;
    }
    if (ppa_hosts[host_no].cur_cmd) {
	printk("PPA: bug in ppa_command\n");
	return 0;
    }
    ppa_hosts[host_no].failed = 0;
    ppa_hosts[host_no].jstart = jiffies;
    ppa_hosts[host_no].cur_cmd = cmd;
    cmd->result = DID_ERROR << 16;	/* default return code */
    cmd->SCp.phase = 0;

    ppa_pb_claim(host_no);

    while (ppa_engine(&ppa_hosts[host_no], cmd))
	schedule();

    if (cmd->SCp.phase)		/* Only disconnect if we have connected */
	ppa_disconnect(cmd->host->unique_id);

    ppa_pb_release(host_no);
    ppa_hosts[host_no].cur_cmd = 0;
    return cmd->result;
}

/*
 * Since the PPA itself doesn't generate interrupts, we use
 * the scheduler's task queue to generate a stream of call-backs and
 * complete the request when the drive is ready.
 */
static void ppa_interrupt(void *data)
{
    ppa_struct *tmp = (ppa_struct *) data;
    Scsi_Cmnd *cmd = tmp->cur_cmd;
    unsigned long flags;

    if (!cmd) {
	printk("PPA: bug in ppa_interrupt\n");
	return;
    }
    if (ppa_engine(tmp, cmd)) {
	tmp->ppa_tq.data = (void *) tmp;
	tmp->ppa_tq.sync = 0;
	queue_task(&tmp->ppa_tq, &tq_timer);
	return;
    }
    /* Command must of completed hence it is safe to let go... */
#if PPA_DEBUG > 0
    switch ((cmd->result >> 16) & 0xff) {
    case DID_OK:
	break;
    case DID_NO_CONNECT:
	printk("ppa: no device at SCSI ID %i\n", cmd->target);
	break;
    case DID_BUS_BUSY:
	printk("ppa: BUS BUSY - EPP timeout detected\n");
	break;
    case DID_TIME_OUT:
	printk("ppa: unknown timeout\n");
	break;
    case DID_ABORT:
	printk("ppa: told to abort\n");
	break;
    case DID_PARITY:
	printk("ppa: parity error (???)\n");
	break;
    case DID_ERROR:
	printk("ppa: internal driver error\n");
	break;
    case DID_RESET:
	printk("ppa: told to reset device\n");
	break;
    case DID_BAD_INTR:
	printk("ppa: bad interrupt (???)\n");
	break;
    default:
	printk("ppa: bad return code (%02x)\n", (cmd->result >> 16) & 0xff);
    }
#endif

    if (cmd->SCp.phase > 1)
	ppa_disconnect(cmd->host->unique_id);
    if (cmd->SCp.phase > 0)
	ppa_pb_release(cmd->host->unique_id);

    tmp->cur_cmd = 0;
    
    spin_lock_irqsave(&io_request_lock, flags);
    cmd->scsi_done(cmd);
    spin_unlock_irqrestore(&io_request_lock, flags);
    return;
}

static int ppa_engine(ppa_struct * tmp, Scsi_Cmnd * cmd)
{
    int host_no = cmd->host->unique_id;
    unsigned short ppb = PPA_BASE(host_no);
    unsigned char l = 0, h = 0;
    int retv;

    /* First check for any errors that may of occurred
     * Here we check for internal errors
     */
    if (tmp->failed)
	return 0;

    switch (cmd->SCp.phase) {
    case 0:			/* Phase 0 - Waiting for parport */
	if ((jiffies - tmp->jstart) > HZ) {
	    /*
	     * We waited more than a second
	     * for parport to call us
	     */
	    ppa_fail(host_no, DID_BUS_BUSY);
	    return 0;
	}
	return 1;		/* wait until ppa_wakeup claims parport */
    case 1:			/* Phase 1 - Connected */
	{			/* Perform a sanity check for cable unplugged */
	    int retv = 2;	/* Failed */

	    ppa_connect(host_no, CONNECT_EPP_MAYBE);

	    w_ctr(ppb, 0xe);
	    if ((r_str(ppb) & 0x08) == 0x08)
		retv--;

	    w_ctr(ppb, 0xc);
	    if ((r_str(ppb) & 0x08) == 0x00)
		retv--;

	    if (retv) {
		if ((jiffies - tmp->jstart) > (1 * HZ)) {
		    printk("ppa: Parallel port cable is unplugged!!\n");
		    ppa_fail(host_no, DID_BUS_BUSY);
		    return 0;
		} else {
		    ppa_disconnect(host_no);
		    return 1;	/* Try again in a jiffy */
		}
	    }
	    cmd->SCp.phase++;
	}

    case 2:			/* Phase 2 - We are now talking to the scsi bus */
	if (!ppa_select(host_no, cmd->target)) {
	    ppa_fail(host_no, DID_NO_CONNECT);
	    return 0;
	}
	cmd->SCp.phase++;

    case 3:			/* Phase 3 - Ready to accept a command */
	w_ctr(ppb, 0x0c);
	if (!(r_str(ppb) & 0x80))
	    return 1;

	if (!ppa_send_command(cmd))
	    return 0;
	cmd->SCp.phase++;

    case 4:			/* Phase 4 - Setup scatter/gather buffers */
	if (cmd->use_sg) {
	    /* if many buffers are available, start filling the first */
	    cmd->SCp.buffer = (struct scatterlist *) cmd->request_buffer;
	    cmd->SCp.this_residual = cmd->SCp.buffer->length;
	    cmd->SCp.ptr = cmd->SCp.buffer->address;
	} else {
	    /* else fill the only available buffer */
	    cmd->SCp.buffer = NULL;
	    cmd->SCp.this_residual = cmd->request_bufflen;
	    cmd->SCp.ptr = cmd->request_buffer;
	}
	cmd->SCp.buffers_residual = cmd->use_sg;
	cmd->SCp.phase++;

    case 5:			/* Phase 5 - Data transfer stage */
	w_ctr(ppb, 0x0c);
	if (!(r_str(ppb) & 0x80))
	    return 1;

	retv = ppa_completion(cmd);
	if (retv == -1)
	    return 0;
	if (retv == 0)
	    return 1;
	cmd->SCp.phase++;

    case 6:			/* Phase 6 - Read status/message */
	cmd->result = DID_OK << 16;
	/* Check for data overrun */
	if (ppa_wait(host_no) != (unsigned char) 0xf0) {
	    ppa_fail(host_no, DID_ERROR);
	    return 0;
	}
	if (ppa_in(host_no, &l, 1)) {	/* read status byte */
	    /* Check for optional message byte */
	    if (ppa_wait(host_no) == (unsigned char) 0xf0)
		ppa_in(host_no, &h, 1);
	    cmd->result = (DID_OK << 16) + (h << 8) + (l & STATUS_MASK);
	}
	return 0;		/* Finished */
	break;

    default:
	printk("ppa: Invalid scsi phase\n");
    }
    return 0;
}

int ppa_queuecommand(Scsi_Cmnd * cmd, void (*done) (Scsi_Cmnd *))
{
    int host_no = cmd->host->unique_id;

    if (ppa_hosts[host_no].cur_cmd) {
	printk("PPA: bug in ppa_queuecommand\n");
	return 0;
    }
    ppa_hosts[host_no].failed = 0;
    ppa_hosts[host_no].jstart = jiffies;
    ppa_hosts[host_no].cur_cmd = cmd;
    cmd->scsi_done = done;
    cmd->result = DID_ERROR << 16;	/* default return code */
    cmd->SCp.phase = 0;		/* bus free */

    ppa_pb_claim(host_no);

    ppa_hosts[host_no].ppa_tq.data = ppa_hosts + host_no;
    ppa_hosts[host_no].ppa_tq.sync = 0;
    queue_task(&ppa_hosts[host_no].ppa_tq, &tq_immediate);
    mark_bh(IMMEDIATE_BH);

    return 0;
}

/*
 * Apparently the the disk->capacity attribute is off by 1 sector 
 * for all disk drives.  We add the one here, but it should really
 * be done in sd.c.  Even if it gets fixed there, this will still
 * work.
 */
int ppa_biosparam(Disk * disk, kdev_t dev, int ip[])
{
    ip[0] = 0x40;
    ip[1] = 0x20;
    ip[2] = (disk->capacity + 1) / (ip[0] * ip[1]);
    if (ip[2] > 1024) {
	ip[0] = 0xff;
	ip[1] = 0x3f;
	ip[2] = (disk->capacity + 1) / (ip[0] * ip[1]);
	if (ip[2] > 1023)
	    ip[2] = 1023;
    }
    return 0;
}

int ppa_abort(Scsi_Cmnd * cmd)
{
    int host_no = cmd->host->unique_id;
    /*
     * There is no method for aborting commands since Iomega
     * have tied the SCSI_MESSAGE line high in the interface
     */

    switch (cmd->SCp.phase) {
    case 0:			/* Do not have access to parport */
    case 1:			/* Have not connected to interface */
	ppa_hosts[host_no].cur_cmd = NULL;	/* Forget the problem */
	return SUCCESS;
	break;
    default:			/* SCSI command sent, can not abort */
	return FAILED;
	break;
    }
}

static void ppa_reset_pulse(unsigned int base)
{
    w_dtr(base, 0x40);
    w_ctr(base, 0x8);
    udelay(30);
    w_ctr(base, 0xc);
}

int ppa_reset(Scsi_Cmnd * cmd)
{
    int host_no = cmd->host->unique_id;

    if (cmd->SCp.phase)
	ppa_disconnect(host_no);
    ppa_hosts[host_no].cur_cmd = NULL;	/* Forget the problem */

    ppa_connect(host_no, CONNECT_NORMAL);
    ppa_reset_pulse(PPA_BASE(host_no));
    udelay(1000);		/* device settle delay */
    ppa_disconnect(host_no);
    udelay(1000);		/* device settle delay */
    return SUCCESS;
}

static int device_check(int host_no)
{
    /* This routine looks for a device and then attempts to use EPP
       to send a command. If all goes as planned then EPP is available. */

    static char cmd[6] =
    {0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
    int loop, old_mode, status, k, ppb = PPA_BASE(host_no);
    unsigned char l;

    old_mode = ppa_hosts[host_no].mode;
    for (loop = 0; loop < 8; loop++) {
	/* Attempt to use EPP for Test Unit Ready */
	if ((ppb & 0x0007) == 0x0000)
	    ppa_hosts[host_no].mode = PPA_EPP_32;

      second_pass:
	ppa_connect(host_no, CONNECT_EPP_MAYBE);
	/* Select SCSI device */
	if (!ppa_select(host_no, loop)) {
	    ppa_disconnect(host_no);
	    continue;
	}
	printk("ppa: Found device at ID %i, Attempting to use %s\n", loop,
	       PPA_MODE_STRING[ppa_hosts[host_no].mode]);

	/* Send SCSI command */
	status = 1;
	w_ctr(ppb, 0x0c);
	for (l = 0; (l < 6) && (status); l++)
	    status = ppa_out(host_no, cmd, 1);

	if (!status) {
	    ppa_disconnect(host_no);
	    ppa_connect(host_no, CONNECT_EPP_MAYBE);
	    w_dtr(ppb, 0x40);
	    w_ctr(ppb, 0x08);
	    udelay(30);
	    w_ctr(ppb, 0x0c);
	    udelay(1000);
	    ppa_disconnect(host_no);
	    udelay(1000);
	    if (ppa_hosts[host_no].mode == PPA_EPP_32) {
		ppa_hosts[host_no].mode = old_mode;
		goto second_pass;
	    }
	    printk("ppa: Unable to establish communication, aborting driver load.\n");
	    return 1;
	}
	w_ctr(ppb, 0x0c);
	k = 1000000;		/* 1 Second */
	do {
	    l = r_str(ppb);
	    k--;
	    udelay(1);
	} while (!(l & 0x80) && (k));

	l &= 0xf0;

	if (l != 0xf0) {
	    ppa_disconnect(host_no);
	    ppa_connect(host_no, CONNECT_EPP_MAYBE);
	    ppa_reset_pulse(ppb);
	    udelay(1000);
	    ppa_disconnect(host_no);
	    udelay(1000);
	    if (ppa_hosts[host_no].mode == PPA_EPP_32) {
		ppa_hosts[host_no].mode = old_mode;
		goto second_pass;
	    }
	    printk("ppa: Unable to establish communication, aborting driver load.\n");
	    return 1;
	}
	ppa_disconnect(host_no);
	printk("ppa: Communication established with ID %i using %s\n", loop,
	       PPA_MODE_STRING[ppa_hosts[host_no].mode]);
	ppa_connect(host_no, CONNECT_EPP_MAYBE);
	ppa_reset_pulse(ppb);
	udelay(1000);
	ppa_disconnect(host_no);
	udelay(1000);
	return 0;
    }
    printk("ppa: No devices found, aborting driver load.\n");
    return 1;
}