mesh.c

讲述linux的初始化过程

	return NOTIFY_DONE;
}

int
mesh_command(Scsi_Cmnd *cmd)
{
	printk(KERN_WARNING "whoops... mesh_command called\n");
	return -1;
}

static void
mesh_init(struct mesh_state *ms)
{
	volatile struct mesh_regs *mr = ms->mesh;
	volatile struct dbdma_regs *md = ms->dma;

	udelay(100);

	out_le32(&md->control, (RUN|PAUSE|FLUSH|WAKE) << 16);	/* stop dma */
	out_8(&mr->exception, 0xff);	/* clear all exception bits */
	out_8(&mr->error, 0xff);	/* clear all error bits */
	out_8(&mr->sequence, SEQ_RESETMESH);
	udelay(10);
	out_8(&mr->intr_mask, INT_ERROR | INT_EXCEPTION | INT_CMDDONE);
	out_8(&mr->source_id, ms->host->this_id);
	out_8(&mr->sel_timeout, 25);	/* 250ms */
	out_8(&mr->sync_params, ASYNC_PARAMS);

	out_8(&mr->bus_status1, BS1_RST);	/* assert RST */
	udelay(30);			/* leave it on for >= 25us */
	out_8(&mr->bus_status1, 0);	/* negate RST */

	out_8(&mr->sequence, SEQ_FLUSHFIFO);
	udelay(1);
	out_8(&mr->sync_params, ASYNC_PARAMS);
	out_8(&mr->sequence, SEQ_ENBRESEL);
	out_8(&mr->interrupt, 0xff);	/* clear all interrupt bits */
}

/*
 * Start the next command for a MESH.
 * Should be called with interrupts disabled.
 */
static void
mesh_start(struct mesh_state *ms)
{
	Scsi_Cmnd *cmd, *prev, *next;

	if (ms->phase != idle || ms->current_req != NULL) {
		printk(KERN_ERR "inappropriate mesh_start (phase=%d, ms=%p)",
		       ms->phase, ms);
		return;
	}

	while (ms->phase == idle) {
		prev = NULL;
		for (cmd = ms->request_q; ; cmd = (Scsi_Cmnd *) cmd->host_scribble) {
			if (cmd == NULL)
				return;
			if (ms->tgts[cmd->target].current_req == NULL)
				break;
			prev = cmd;
		}
		next = (Scsi_Cmnd *) cmd->host_scribble;
		if (prev == NULL)
			ms->request_q = next;
		else
			prev->host_scribble = (void *) next;
		if (next == NULL)
			ms->request_qtail = prev;

		mesh_start_cmd(ms, cmd);
	}
}

static void
mesh_start_cmd(struct mesh_state *ms, Scsi_Cmnd *cmd)
{
	volatile struct mesh_regs *mr = ms->mesh;
	int t;

	ms->current_req = cmd;
	ms->tgts[cmd->target].data_goes_out = data_goes_out(cmd);
	ms->tgts[cmd->target].current_req = cmd;

#if 1
	if (DEBUG_TARGET(cmd)) {
		int i;
		printk(KERN_DEBUG "mesh_start: %p ser=%lu tgt=%d cmd=",
		       cmd, cmd->serial_number, cmd->target);
		for (i = 0; i < cmd->cmd_len; ++i)
			printk(" %x", cmd->cmnd[i]);
		printk(" use_sg=%d buffer=%p bufflen=%u\n",
		       cmd->use_sg, cmd->request_buffer, cmd->request_bufflen);
	}
#endif

	ms->phase = arbitrating;
	ms->msgphase = msg_none;
	ms->data_ptr = 0;
	ms->dma_started = 0;
	ms->n_msgout = 0;
	ms->last_n_msgout = 0;
	ms->expect_reply = 0;
	ms->conn_tgt = cmd->target;
	ms->tgts[cmd->target].saved_ptr = 0;
	ms->stat = DID_OK;
	ms->aborting = 0;
#ifdef MESH_DBG
	ms->tgts[cmd->target].n_log = 0;
	dlog(ms, "start cmd=%x", (int) cmd);
#endif

	/* Off we go */
	dlog(ms, "about to arb, intr/exc/err/fc=%.8x",
	     MKWORD(mr->interrupt, mr->exception, mr->error, mr->fifo_count));
	out_8(&mr->interrupt, INT_CMDDONE);
	out_8(&mr->sequence, SEQ_ENBRESEL);
	udelay(1);

	if (mr->bus_status1 & (BS1_BSY | BS1_SEL)) {
		/*
		 * Some other device has the bus or is arbitrating for it -
		 * probably a target which is about to reselect us.
		 */
		dlog(ms, "busy b4 arb, intr/exc/err/fc=%.8x",
		     MKWORD(mr->interrupt, mr->exception,
			    mr->error, mr->fifo_count));
		for (t = 100; t > 0; --t) {
			if ((mr->bus_status1 & (BS1_BSY | BS1_SEL)) == 0)
				break;
			if (in_8(&mr->interrupt) != 0) {
				dlog(ms, "intr b4 arb, intr/exc/err/fc=%.8x",
				     MKWORD(mr->interrupt, mr->exception,
					    mr->error, mr->fifo_count));
				mesh_interrupt(0, (void *)ms, 0);
				if (ms->phase != arbitrating)
					return;
			}
			udelay(1);
		}
		if (mr->bus_status1 & (BS1_BSY | BS1_SEL)) {
			/* XXX should try again in a little while */
			ms->stat = DID_BUS_BUSY;
			ms->phase = idle;
			mesh_done(ms, 0);
			return;
		}
	}

	/*
	 * Apparently the mesh has a bug where it will assert both its
	 * own bit and the target's bit on the bus during arbitration.
	 */
	out_8(&mr->dest_id, mr->source_id);

	/*
	 * There appears to be a race with reselection sometimes,
	 * where a target reselects us just as we issue the
	 * arbitrate command.  It seems that then the arbitrate
	 * command just hangs waiting for the bus to be free
	 * without giving us a reselection exception.
	 * The only way I have found to get it to respond correctly
	 * is this: disable reselection before issuing the arbitrate
	 * command, then after issuing it, if it looks like a target
	 * is trying to reselect us, reset the mesh and then enable
	 * reselection.
	 */
	out_8(&mr->sequence, SEQ_DISRESEL);
	if (in_8(&mr->interrupt) != 0) {
		dlog(ms, "intr after disresel, intr/exc/err/fc=%.8x",
		     MKWORD(mr->interrupt, mr->exception,
			    mr->error, mr->fifo_count));
		mesh_interrupt(0, (void *)ms, 0);
		if (ms->phase != arbitrating)
			return;
		dlog(ms, "after intr after disresel, intr/exc/err/fc=%.8x",
		     MKWORD(mr->interrupt, mr->exception,
			    mr->error, mr->fifo_count));
	}

	out_8(&mr->sequence, SEQ_ARBITRATE);

	for (t = 230; t > 0; --t) {
		if (in_8(&mr->interrupt) != 0)
			break;
		udelay(1);
	}
	dlog(ms, "after arb, intr/exc/err/fc=%.8x",
	     MKWORD(mr->interrupt, mr->exception, mr->error, mr->fifo_count));
	if (mr->interrupt == 0 && (mr->bus_status1 & BS1_SEL)
	    && (mr->bus_status0 & BS0_IO)) {
		/* looks like a reselection - try resetting the mesh */
		dlog(ms, "resel? after arb, intr/exc/err/fc=%.8x",
		     MKWORD(mr->interrupt, mr->exception, mr->error, mr->fifo_count));
		out_8(&mr->sequence, SEQ_RESETMESH);
		udelay(10);
		out_8(&mr->interrupt, INT_ERROR | INT_EXCEPTION | INT_CMDDONE);
		out_8(&mr->intr_mask, INT_ERROR | INT_EXCEPTION | INT_CMDDONE);
		out_8(&mr->sequence, SEQ_ENBRESEL);
		for (t = 10; t > 0 && mr->interrupt == 0; --t)
			udelay(1);
		dlog(ms, "tried reset after arb, intr/exc/err/fc=%.8x",
		     MKWORD(mr->interrupt, mr->exception, mr->error, mr->fifo_count));
#ifndef MESH_MULTIPLE_HOSTS
		if (mr->interrupt == 0 && (mr->bus_status1 & BS1_SEL)
		    && (mr->bus_status0 & BS0_IO)) {
			printk(KERN_ERR "mesh: controller not responding"
			       " to reselection!\n");
			/*
			 * If this is a target reselecting us, and the
			 * mesh isn't responding, the higher levels of
			 * the scsi code will eventually time out and
			 * reset the bus.
			 */
		}
#endif
	}
}

#ifndef MESH_NEW_STYLE_EH
static void
finish_cmds(void *data)
{
	struct mesh_state *ms = data;
	Scsi_Cmnd *cmd;
	unsigned long flags;

	for (;;) {
		spin_lock_irqsave(&io_request_lock, flags);
		cmd = ms->completed_q;
		if (cmd == NULL) {
			spin_unlock_irqrestore(&io_request_lock, flags);
			break;
		}
		ms->completed_q = (Scsi_Cmnd *) cmd->host_scribble;
		(*cmd->scsi_done)(cmd);
		spin_unlock_irqrestore(&io_request_lock, flags);
	}
}
#endif /* MESH_NEW_STYLE_EH */

static inline void
add_sdtr_msg(struct mesh_state *ms)
{
	int i = ms->n_msgout;

	ms->msgout[i] = EXTENDED_MESSAGE;
	ms->msgout[i+1] = 3;
	ms->msgout[i+2] = EXTENDED_SDTR;
	ms->msgout[i+3] = mesh_sync_period/4;
	ms->msgout[i+4] = (ALLOW_SYNC(ms->conn_tgt)? mesh_sync_offset: 0);
	ms->n_msgout = i + 5;
}

static void
set_sdtr(struct mesh_state *ms, int period, int offset)
{
	struct mesh_target *tp = &ms->tgts[ms->conn_tgt];
	volatile struct mesh_regs *mr = ms->mesh;
	int v, tr;

	tp->sdtr_state = sdtr_done;
	if (offset == 0) {
		/* asynchronous */
		if (SYNC_OFF(tp->sync_params))
			printk(KERN_INFO "mesh: target %d now asynchronous\n",
			       ms->conn_tgt);
		tp->sync_params = ASYNC_PARAMS;
		out_8(&mr->sync_params, ASYNC_PARAMS);
		return;
	}
	/*
	 * We need to compute ceil(clk_freq * period / 500e6) - 2
	 * without incurring overflow.
	 */
	v = (ms->clk_freq / 5000) * period;
	if (v <= 250000) {
		/* special case: sync_period == 5 * clk_period */
		v = 0;
		/* units of tr are 100kB/s */
		tr = (ms->clk_freq + 250000) / 500000;
	} else {
		/* sync_period == (v + 2) * 2 * clk_period */
		v = (v + 99999) / 100000 - 2;
		if (v > 15)
			v = 15;	/* oops */
		tr = ((ms->clk_freq / (v + 2)) + 199999) / 200000;
	}
	if (offset > 15)
		offset = 15;	/* can't happen */
	tp->sync_params = SYNC_PARAMS(offset, v);
	out_8(&mr->sync_params, tp->sync_params);
	printk(KERN_INFO "mesh: target %d synchronous at %d.%d MB/s\n",
	       ms->conn_tgt, tr/10, tr%10);
}

static void
start_phase(struct mesh_state *ms)
{
	int i, seq, nb;
	volatile struct mesh_regs *mr = ms->mesh;
	volatile struct dbdma_regs *md = ms->dma;
	Scsi_Cmnd *cmd = ms->current_req;
	struct mesh_target *tp = &ms->tgts[ms->conn_tgt];

	dlog(ms, "start_phase nmo/exc/fc/seq = %.8x",
	     MKWORD(ms->n_msgout, mr->exception, mr->fifo_count, mr->sequence));
	out_8(&mr->interrupt, INT_ERROR | INT_EXCEPTION | INT_CMDDONE);
	seq = use_active_neg + (ms->n_msgout? SEQ_ATN: 0);
	switch (ms->msgphase) {
	case msg_none:
		break;

	case msg_in:
		out_8(&mr->count_hi, 0);
		out_8(&mr->count_lo, 1);
		out_8(&mr->sequence, SEQ_MSGIN + seq);
		ms->n_msgin = 0;
		return;

	case msg_out:
		/*
		 * To make sure ATN drops before we assert ACK for
		 * the last byte of the message, we have to do the
		 * last byte specially.
		 */
		if (ms->n_msgout <= 0) {
			printk(KERN_ERR "mesh: msg_out but n_msgout=%d\n",
			       ms->n_msgout);
			mesh_dump_regs(ms);
			ms->msgphase = msg_none;
			break;
		}
		if (ALLOW_DEBUG(ms->conn_tgt)) {
			printk(KERN_DEBUG "mesh: sending %d msg bytes:",
			       ms->n_msgout);
			for (i = 0; i < ms->n_msgout; ++i)
				printk(" %x", ms->msgout[i]);
			printk("\n");
		}
		dlog(ms, "msgout msg=%.8x", MKWORD(ms->n_msgout, ms->msgout[0],
						ms->msgout[1], ms->msgout[2]));
		out_8(&mr->count_hi, 0);
		out_8(&mr->sequence, SEQ_FLUSHFIFO);
		udelay(1);
		/*
		 * If ATN is not already asserted, we assert it, then
		 * issue a SEQ_MSGOUT to get the mesh to drop ACK.
		 */
		if ((mr->bus_status0 & BS0_ATN) == 0) {
			dlog(ms, "bus0 was %.2x explictly asserting ATN", mr->bus_status0);
			out_8(&mr->bus_status0, BS0_ATN); /* explicit ATN */
			udelay(1);
			out_8(&mr->count_lo, 1);
			out_8(&mr->sequence, SEQ_MSGOUT + seq);
			out_8(&mr->bus_status0, 0); /* release explicit ATN */
			dlog(ms,"hace: after explicit ATN bus0=%.2x",mr->bus_status0);
		}
		if (ms->n_msgout == 1) {
			/*
			 * We can't issue the SEQ_MSGOUT without ATN
			 * until the target has asserted REQ.  The logic
			 * in cmd_complete handles both situations:
			 * REQ already asserted or not.
			 */
			cmd_complete(ms);
		} else {
			out_8(&mr->count_lo, ms->n_msgout - 1);
			out_8(&mr->sequence, SEQ_MSGOUT + seq);
			for (i = 0; i < ms->n_msgout - 1; ++i)
				out_8(&mr->fifo, ms->msgout[i]);
		}
		return;

	default:
		printk(KERN_ERR "mesh bug: start_phase msgphase=%d\n",
		       ms->msgphase);
	}

	switch (ms->phase) {
	case selecting:
		out_8(&mr->dest_id, ms->conn_tgt);
		out_8(&mr->sequence, SEQ_SELECT + SEQ_ATN);
		break;
	case commanding:
		out_8(&mr->sync_params, tp->sync_params);
		out_8(&mr->count_hi, 0);
		if (cmd) {
			out_8(&mr->count_lo, cmd->cmd_len);
			out_8(&mr->sequence, SEQ_COMMAND + seq);
			for (i = 0; i < cmd->cmd_len; ++i)
				out_8(&mr->fifo, cmd->cmnd[i]);
		} else {
			out_8(&mr->count_lo, 6);
			out_8(&mr->sequence, SEQ_COMMAND + seq);
			for (i = 0; i < 6; ++i)
				out_8(&mr->fifo, 0);
		}
		break;
	case dataing:
		/* transfer data, if any */
		if (!ms->dma_started) {
			set_dma_cmds(ms, cmd);
			out_le32(&md->cmdptr, virt_to_phys(ms->dma_cmds));
			out_le32(&md->control, (RUN << 16) | RUN);
			ms->dma_started = 1;
		}
		nb = ms->dma_count;
		if (nb > 0xfff0)
			nb = 0xfff0;
		ms->dma_count -= nb;
		ms->data_ptr += nb;
		out_8(&mr->count_lo, nb);
		out_8(&mr->count_hi, nb >> 8);
		out_8(&mr->sequence, (tp->data_goes_out?
				SEQ_DATAOUT: SEQ_DATAIN) + SEQ_DMA_MODE + seq);
		break;
	case statusing:
		out_8(&mr->count_hi, 0);
		out_8(&mr->count_lo, 1);
		out_8(&mr->sequence, SEQ_STATUS + seq);
		break;
	case busfreeing:
	case disconnecting:
		out_8(&mr->sequence, SEQ_ENBRESEL);
		udelay(1);
		dlog(ms, "enbresel intr/exc/err/fc=%.8x",
		     MKWORD(mr->interrupt, mr->exception, mr->error,
			    mr->fifo_count));
		out_8(&mr->sequence, SEQ_BUSFREE);
		break;
	default:
		printk(KERN_ERR "mesh: start_phase called with phase=%d\n",
		       ms->phase);
		dumpslog(ms);
	}

}

static inline void
get_msgin(struct mesh_state *ms)
{
	volatile struct mesh_regs *mr = ms->mesh;
	int i, n;

	n = mr->fifo_count;
	if (n != 0) {
		i = ms->n_msgin;
		ms->n_msgin = i + n;
		for (; n > 0; --n)
			ms->msgin[i++] = in_8(&mr->fifo);
	}
}

static inline int
msgin_length(struct mesh_state *ms)
{
	int b, n;

	n = 1;
	if (ms->n_msgin > 0) {
		b = ms->msgin[0];
		if (b == 1) {
			/* extended message */
			n = ms->n_msgin < 2? 2: ms->msgin[1] + 2;
		} else if (0x20 <= b && b <= 0x2f) {
			/* 2-byte message */
			n = 2;
		}
	}
	return n;
}

static void
cmd_complete(struct mesh_state *ms)
{
	volatile struct mesh_regs *mr = ms->mesh;
	Scsi_Cmnd *cmd = ms->current_req;
	struct mesh_target *tp = &ms->tgts[ms->conn_tgt];
	int seq, n, t;

	dlog(ms, "cmd_complete fc=%x", mr->fifo_count);
	seq = use_active_neg + (ms->n_msgout? SEQ_ATN: 0);
	switch (ms->msgphase) {