wd33c93.c

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 * 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.
	 */

	spin_lock_irq(&hostdata->lock);

	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 = (struct scsi_cmnd *) hostdata->input_Q;
		     tmp->host_scribble;
		     tmp = (struct 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!
 */

	wd33c93_execute(cmd->device->host);

	DB(DB_QUEUE_COMMAND, printk(")Q-%ld ", cmd->serial_number))

	spin_unlock_irq(&hostdata->lock);
	return 0;
}

/*
 * This routine attempts to start a scsi command. If the host_card is
 * already connected, we give up immediately. Otherwise, look through
 * the input_Q, using the first command we find that's intended
 * for a currently non-busy target/lun.
 *
 * wd33c93_execute() is always called with interrupts disabled or from
 * the wd33c93_intr itself, which means that a wd33c93 interrupt
 * cannot occur while we are in here.
 */
static void
wd33c93_execute(struct Scsi_Host *instance)
{
	struct WD33C93_hostdata *hostdata =
	    (struct WD33C93_hostdata *) instance->hostdata;
	const wd33c93_regs regs = hostdata->regs;
	struct scsi_cmnd *cmd, *prev;

	DB(DB_EXECUTE, printk("EX("))
	if (hostdata->selecting || hostdata->connected) {
		DB(DB_EXECUTE, printk(")EX-0 "))
		return;
	}

	/*
	 * Search through the input_Q for a command destined
	 * for an idle target/lun.
	 */

	cmd = (struct scsi_cmnd *) hostdata->input_Q;
	prev = NULL;
	while (cmd) {
		if (!(hostdata->busy[cmd->device->id] & (1 << cmd->device->lun)))
			break;
		prev = cmd;
		cmd = (struct scsi_cmnd *) cmd->host_scribble;
	}

	/* quit if queue empty or all possible targets are busy */

	if (!cmd) {
		DB(DB_EXECUTE, printk(")EX-1 "))
		return;
	}

	/*  remove command from queue */

	if (prev)
		prev->host_scribble = cmd->host_scribble;
	else
		hostdata->input_Q = (struct scsi_cmnd *) cmd->host_scribble;

#ifdef PROC_STATISTICS
	hostdata->cmd_cnt[cmd->device->id]++;
#endif

	/*
	 * Start the selection process
	 */

	if (cmd->sc_data_direction == DMA_TO_DEVICE)
		write_wd33c93(regs, WD_DESTINATION_ID, cmd->device->id);
	else
		write_wd33c93(regs, WD_DESTINATION_ID, cmd->device->id | DSTID_DPD);

/* Now we need to figure out whether or not this command is a good
 * candidate for disconnect/reselect. We guess to the best of our
 * ability, based on a set of hierarchical rules. When several
 * devices are operating simultaneously, disconnects are usually
 * an advantage. In a single device system, or if only 1 device
 * is being accessed, transfers usually go faster if disconnects
 * are not allowed:
 *
 * + Commands should NEVER disconnect if hostdata->disconnect =
 *   DIS_NEVER (this holds for tape drives also), and ALWAYS
 *   disconnect if hostdata->disconnect = DIS_ALWAYS.
 * + Tape drive commands should always be allowed to disconnect.
 * + Disconnect should be allowed if disconnected_Q isn't empty.
 * + Commands should NOT disconnect if input_Q is empty.
 * + Disconnect should be allowed if there are commands in input_Q
 *   for a different target/lun. In this case, the other commands
 *   should be made disconnect-able, if not already.
 *
 * I know, I know - this code would flunk me out of any
 * "C Programming 101" class ever offered. But it's easy
 * to change around and experiment with for now.
 */

	cmd->SCp.phase = 0;	/* assume no disconnect */
	if (hostdata->disconnect == DIS_NEVER)
		goto no;
	if (hostdata->disconnect == DIS_ALWAYS)
		goto yes;
	if (cmd->device->type == 1)	/* tape drive? */
		goto yes;
	if (hostdata->disconnected_Q)	/* other commands disconnected? */
		goto yes;
	if (!(hostdata->input_Q))	/* input_Q empty? */
		goto no;
	for (prev = (struct scsi_cmnd *) hostdata->input_Q; prev;
	     prev = (struct scsi_cmnd *) prev->host_scribble) {
		if ((prev->device->id != cmd->device->id) ||
		    (prev->device->lun != cmd->device->lun)) {
			for (prev = (struct scsi_cmnd *) hostdata->input_Q; prev;
			     prev = (struct scsi_cmnd *) prev->host_scribble)
				prev->SCp.phase = 1;
			goto yes;
		}
	}

	goto no;

 yes:
	cmd->SCp.phase = 1;

#ifdef PROC_STATISTICS
	hostdata->disc_allowed_cnt[cmd->device->id]++;
#endif

 no:

	write_wd33c93(regs, WD_SOURCE_ID, ((cmd->SCp.phase) ? SRCID_ER : 0));

	write_wd33c93(regs, WD_TARGET_LUN, cmd->device->lun);
	write_wd33c93(regs, WD_SYNCHRONOUS_TRANSFER,
		      hostdata->sync_xfer[cmd->device->id]);
	hostdata->busy[cmd->device->id] |= (1 << cmd->device->lun);

	if ((hostdata->level2 == L2_NONE) ||
	    (hostdata->sync_stat[cmd->device->id] == SS_UNSET)) {

		/*
		 * Do a 'Select-With-ATN' command. This will end with
		 * one of the following interrupts:
		 *    CSR_RESEL_AM:  failure - can try again later.
		 *    CSR_TIMEOUT:   failure - give up.
		 *    CSR_SELECT:    success - proceed.
		 */

		hostdata->selecting = cmd;

/* Every target has its own synchronous transfer setting, kept in the
 * sync_xfer array, and a corresponding status byte in sync_stat[].
 * Each target's sync_stat[] entry is initialized to SX_UNSET, and its
 * sync_xfer[] entry is initialized to the default/safe value. SS_UNSET
 * means that the parameters are undetermined as yet, and that we
 * need to send an SDTR message to this device after selection is
 * complete: We set SS_FIRST to tell the interrupt routine to do so.
 * If we've been asked not to try synchronous transfers on this
 * target (and _all_ luns within it), we'll still send the SDTR message
 * later, but at that time we'll negotiate for async by specifying a
 * sync fifo depth of 0.
 */
		if (hostdata->sync_stat[cmd->device->id] == SS_UNSET)
			hostdata->sync_stat[cmd->device->id] = SS_FIRST;
		hostdata->state = S_SELECTING;
		write_wd33c93_count(regs, 0);	/* guarantee a DATA_PHASE interrupt */
		write_wd33c93_cmd(regs, WD_CMD_SEL_ATN);
	} else {

		/*
		 * Do a 'Select-With-ATN-Xfer' command. This will end with
		 * one of the following interrupts:
		 *    CSR_RESEL_AM:  failure - can try again later.
		 *    CSR_TIMEOUT:   failure - give up.
		 *    anything else: success - proceed.
		 */

		hostdata->connected = cmd;
		write_wd33c93(regs, WD_COMMAND_PHASE, 0);

		/* copy command_descriptor_block into WD chip
		 * (take advantage of auto-incrementing)
		 */

		write_wd33c93_cdb(regs, cmd->cmd_len, cmd->cmnd);

		/* The wd33c93 only knows about Group 0, 1, and 5 commands when
		 * it's doing a 'select-and-transfer'. To be safe, we write the
		 * size of the CDB into the OWN_ID register for every case. This
		 * way there won't be problems with vendor-unique, audio, etc.
		 */

		write_wd33c93(regs, WD_OWN_ID, cmd->cmd_len);

		/* When doing a non-disconnect command with DMA, we can save
		 * ourselves a DATA phase interrupt later by setting everything
		 * up ahead of time.
		 */

		if ((cmd->SCp.phase == 0) && (hostdata->no_dma == 0)) {
			if (hostdata->dma_setup(cmd,
			    (cmd->sc_data_direction == DMA_TO_DEVICE) ?
			     DATA_OUT_DIR : DATA_IN_DIR))
				write_wd33c93_count(regs, 0);	/* guarantee a DATA_PHASE interrupt */
			else {
				write_wd33c93_count(regs,
						    cmd->SCp.this_residual);
				write_wd33c93(regs, WD_CONTROL,
					      CTRL_IDI | CTRL_EDI | hostdata->dma_mode);
				hostdata->dma = D_DMA_RUNNING;
			}
		} else
			write_wd33c93_count(regs, 0);	/* guarantee a DATA_PHASE interrupt */

		hostdata->state = S_RUNNING_LEVEL2;
		write_wd33c93_cmd(regs, WD_CMD_SEL_ATN_XFER);
	}

	/*
	 * Since the SCSI bus can handle only 1 connection at a time,
	 * we get out of here now. If the selection fails, or when
	 * the command disconnects, we'll come back to this routine
	 * to search the input_Q again...
	 */

	DB(DB_EXECUTE,
	   printk("%s%ld)EX-2 ", (cmd->SCp.phase) ? "d:" : "", cmd->serial_number))
}

static void
transfer_pio(const wd33c93_regs regs, uchar * buf, int cnt,
	     int data_in_dir, struct WD33C93_hostdata *hostdata)
{
	uchar asr;

	DB(DB_TRANSFER,
	   printk("(%p,%d,%s:", buf, cnt, data_in_dir ? "in" : "out"))

	write_wd33c93(regs, WD_CONTROL, CTRL_IDI | CTRL_EDI | CTRL_POLLED);
	write_wd33c93_count(regs, cnt);
	write_wd33c93_cmd(regs, WD_CMD_TRANS_INFO);
	if (data_in_dir) {
		do {
			asr = read_aux_stat(regs);
			if (asr & ASR_DBR)
				*buf++ = read_wd33c93(regs, WD_DATA);
		} while (!(asr & ASR_INT));
	} else {
		do {
			asr = read_aux_stat(regs);
			if (asr & ASR_DBR)
				write_wd33c93(regs, WD_DATA, *buf++);
		} while (!(asr & ASR_INT));
	}

	/* Note: we are returning with the interrupt UN-cleared.
	 * Since (presumably) an entire I/O operation has
	 * completed, the bus phase is probably different, and
	 * the interrupt routine will discover this when it
	 * responds to the uncleared int.
	 */

}

static void
transfer_bytes(const wd33c93_regs regs, struct scsi_cmnd *cmd,
		int data_in_dir)
{
	struct WD33C93_hostdata *hostdata;
	unsigned long length;

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

/* Normally, you'd expect 'this_residual' to be non-zero here.
 * In a series of scatter-gather transfers, however, this
 * routine will usually be called with 'this_residual' equal
 * to 0 and 'buffers_residual' non-zero. This means that a
 * previous transfer completed, clearing 'this_residual', and
 * now we need to setup the next scatter-gather buffer as the
 * source or destination for THIS transfer.
 */
	if (!cmd->SCp.this_residual && cmd->SCp.buffers_residual) {
		++cmd->SCp.buffer;
		--cmd->SCp.buffers_residual;
		cmd->SCp.this_residual = cmd->SCp.buffer->length;
		cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
	}
	if (!cmd->SCp.this_residual) /* avoid bogus setups */
		return;

	write_wd33c93(regs, WD_SYNCHRONOUS_TRANSFER,
		      hostdata->sync_xfer[cmd->device->id]);

/* 'hostdata->no_dma' is TRUE if we don't even want to try DMA.
 * Update 'this_residual' and 'ptr' after 'transfer_pio()' returns.
 */

	if (hostdata->no_dma || hostdata->dma_setup(cmd, data_in_dir)) {
#ifdef PROC_STATISTICS
		hostdata->pio_cnt++;
#endif
		transfer_pio(regs, (uchar *) cmd->SCp.ptr,
			     cmd->SCp.this_residual, data_in_dir, hostdata);
		length = cmd->SCp.this_residual;
		cmd->SCp.this_residual = read_wd33c93_count(regs);
		cmd->SCp.ptr += (length - cmd->SCp.this_residual);
	}

/* We are able to do DMA (in fact, the Amiga hardware is
 * already going!), so start up the wd33c93 in DMA mode.
 * We set 'hostdata->dma' = D_DMA_RUNNING so that when the
 * transfer completes and causes an interrupt, we're
 * reminded to tell the Amiga to shut down its end. We'll
 * postpone the updating of 'this_residual' and 'ptr'
 * until then.
 */

	else {
#ifdef PROC_STATISTICS
		hostdata->dma_cnt++;
#endif
		write_wd33c93(regs, WD_CONTROL, CTRL_IDI | CTRL_EDI | hostdata->dma_mode);
		write_wd33c93_count(regs, cmd->SCp.this_residual);

		if ((hostdata->level2 >= L2_DATA) ||
		    (hostdata->level2 == L2_BASIC && cmd->SCp.phase == 0)) {
			write_wd33c93(regs, WD_COMMAND_PHASE, 0x45);
			write_wd33c93_cmd(regs, WD_CMD_SEL_ATN_XFER);
			hostdata->state = S_RUNNING_LEVEL2;
		} else
			write_wd33c93_cmd(regs, WD_CMD_TRANS_INFO);

		hostdata->dma = D_DMA_RUNNING;
	}
}

void
wd33c93_intr(struct Scsi_Host *instance)
{
	struct WD33C93_hostdata *hostdata =
	    (struct WD33C93_hostdata *) instance->hostdata;
	const wd33c93_regs regs = hostdata->regs;
	struct scsi_cmnd *patch, *cmd;
	uchar asr, sr, phs, id, lun, *ucp, msg;
	unsigned long length, flags;

	asr = read_aux_stat(regs);
	if (!(asr & ASR_INT) || (asr & ASR_BSY))
		return;

	spin_lock_irqsave(&hostdata->lock, flags);

#ifdef PROC_STATISTICS
	hostdata->int_cnt++;
#endif

	cmd = (struct scsi_cmnd *) hostdata->connected;	/* assume we're connected */
	sr = read_wd33c93(regs, WD_SCSI_STATUS);	/* clear the interrupt */
	phs = read_wd33c93(regs, WD_COMMAND_PHASE);

	DB(DB_INTR, printk("{%02x:%02x-", asr, sr))

/* After starting a DMA transfer, the next interrupt
 * is guaranteed to be in response to completion of
 * the transfer. Since the Amiga DMA hardware runs in
 * in an open-ended fashion, it needs to be told when
 * to stop; do that here if D_DMA_RUNNING is true.
 * Also, we have to update 'this_residual' and 'ptr'
 * based on the contents of the TRANSFER_COUNT register,
 * in case the device decided to do an intermediate
 * disconnect (a device may do this if it has to do a
 * seek, or just to be nice and let other devices have
 * some bus time during long transfers). After doing
 * whatever is needed, we go on and service the WD3393
 * interrupt normally.
 */
	    if (hostdata->dma == D_DMA_RUNNING) {
		DB(DB_TRANSFER,
		   printk("[%p/%d:", cmd->SCp.ptr, cmd->SCp.this_residual))
		    hostdata->dma_stop(cmd->device->host, cmd, 1);
		hostdata->dma = D_DMA_OFF;
		length = cmd->SCp.this_residual;
		cmd->SCp.this_residual = read_wd33c93_count(regs);
		cmd->SCp.ptr += (length - cmd->SCp.this_residual);
		DB(DB_TRANSFER,
		   printk("%p/%d]", cmd->SCp.ptr, cmd->SCp.this_residual))
	}

/* Respond to the specific WD3393 interrupt - there are quite a few! */
	switch (sr) {
	case CSR_TIMEOUT:
		DB(DB_INTR, printk("TIMEOUT"))

		    if (hostdata->state == S_RUNNING_LEVEL2)
			hostdata->connected = NULL;
		else {
			cmd = (struct scsi_cmnd *) hostdata->selecting;	/* get a valid cmd */