patch-2.1.51 linux/drivers/scsi/mesh.c

• Lines: 1322
• Date: Sat Aug 16 10:09:10 1997
• Orig file: v2.1.50/linux/drivers/scsi/mesh.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.50/linux/drivers/scsi/mesh.c linux/drivers/scsi/mesh.c
@@ -0,0 +1,1321 @@
+/*
+ * SCSI low-level driver for the MESH (Macintosh Enhanced SCSI Hardware)
+ * bus adaptor found on Power Macintosh computers.
+ * We assume the MESH is connected to a DBDMA (descriptor-based DMA)
+ * controller.
+ *
+ * Paul Mackerras, August 1996.
+ * Copyright (C) 1996 Paul Mackerras.
+ */
+
+#include <linux/config.h>
+
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/malloc.h>
+#include <linux/blk.h>
+#include <linux/proc_fs.h>
+#include <linux/stat.h>
+#include <linux/tqueue.h>
+#include <linux/interrupt.h>
+#include <linux/reboot.h>
+#include <asm/dbdma.h>
+#include <asm/io.h>
+#include <asm/prom.h>
+#include <asm/system.h>
+
+#include "scsi.h"
+#include "hosts.h"
+#include "mesh.h"
+
+#if 0
+#undef KERN_DEBUG
+#define KERN_DEBUG KERN_WARNING
+#endif
+
+#if CONFIG_SCSI_MESH_SYNC_RATE == 0
+int mesh_sync_period = 100;
+int mesh_sync_offset = 0;
+#else
+int mesh_sync_period = 1000 / CONFIG_SCSI_MESH_SYNC_RATE;	/* ns */
+int mesh_sync_offset = 15;
+#endif
+
+int mesh_sync_targets = 0xff;	/* targets to set synchronous (bitmap) */
+int mesh_resel_targets = 0xff;	/* targets that we let disconnect (bitmap) */
+int mesh_debug_targets = 0;	/* print debug for these targets */
+
+#define ALLOW_SYNC(tgt)		((mesh_sync_targets >> (tgt)) & 1)
+#define ALLOW_RESEL(tgt)	((mesh_resel_targets >> (tgt)) & 1)
+#define ALLOW_DEBUG(tgt)	((mesh_debug_targets >> (tgt)) & 1)
+#define DEBUG_TARGET(cmd)	((cmd) && ALLOW_DEBUG((cmd)->target))
+
+struct proc_dir_entry proc_scsi_mesh = {
+	PROC_SCSI_MESH, 4, "mesh",
+	S_IFDIR | S_IRUGO | S_IXUGO, 2
+};
+
+enum mesh_phase {
+	idle,
+	arbitrating,
+	selecting,
+	commanding,
+	dataing,
+	statusing,
+	busfreeing,
+	disconnecting,
+	reselecting
+};
+
+enum msg_phase {
+	msg_none,
+	msg_out,
+	msg_out_xxx,
+	msg_out_last,
+	msg_in,
+};
+
+enum sdtr_phase {
+	do_sdtr,
+	sdtr_sent,
+	sdtr_done
+};
+
+struct mesh_target {
+	enum sdtr_phase sdtr_state;
+	enum mesh_phase phase;
+	int	sync_params;
+	int	data_goes_out;
+	Scsi_Cmnd *current_req;
+	u32	saved_ptr;
+};
+
+struct mesh_state {
+	volatile struct	mesh_regs *mesh;
+	int	meshintr;
+	volatile struct	dbdma_regs *dma;
+	int	dmaintr;
+	struct	Scsi_Host *host;
+	struct	mesh_state *next;
+	Scsi_Cmnd *request_q;
+	Scsi_Cmnd *request_qtail;
+	enum mesh_phase phase;		/* what we're currently trying to do */
+	enum msg_phase msgphase;
+	int	conn_tgt;		/* target we're connected to */
+	Scsi_Cmnd *current_req;		/* req we're currently working on */
+	int	data_ptr;
+	int	data_goes_out;		/* guess as to data direction */
+	int	dma_started;
+	int	dma_count;
+	int	expect_reply;
+	int	n_msgin;
+	u8	msgin[16];
+	int	n_msgout;
+	int	last_n_msgout;
+	u8	msgout[16];
+	struct dbdma_cmd *dma_cmds;	/* space for dbdma commands, aligned */
+	int	clk_freq;
+	struct mesh_target tgts[8];
+	struct tq_struct tqueue;
+	Scsi_Cmnd *completed_q;
+	Scsi_Cmnd *completed_qtail;
+};
+
+static struct mesh_state *all_meshes;
+
+static void mesh_init(struct mesh_state *);
+static int mesh_notify_reboot(struct notifier_block *, unsigned long, void *);
+static void mesh_dump_regs(struct mesh_state *);
+static void mesh_start(struct mesh_state *);
+static void finish_cmds(void *);
+static void add_sdtr_msg(struct mesh_state *);
+static void set_sdtr(struct mesh_state *, int, int);
+static void start_phase(struct mesh_state *);
+static void get_msgin(struct mesh_state *);
+static int msgin_length(struct mesh_state *);
+static void cmd_complete(struct mesh_state *);
+static void phase_mismatch(struct mesh_state *);
+static void reselected(struct mesh_state *);
+static void handle_reset(struct mesh_state *);
+static void mesh_interrupt(int, void *, struct pt_regs *);
+static void handle_msgin(struct mesh_state *);
+static void mesh_done(struct mesh_state *);
+static void mesh_completed(struct mesh_state *, Scsi_Cmnd *);
+static void set_dma_cmds(struct mesh_state *, Scsi_Cmnd *);
+static void halt_dma(struct mesh_state *);
+static int data_goes_out(Scsi_Cmnd *);
+
+static struct notifier_block mesh_notifier = {
+	mesh_notify_reboot,
+	NULL,
+	0
+};
+
+int
+mesh_detect(Scsi_Host_Template *tp)
+{
+	struct device_node *mesh;
+	int nmeshes, tgt, *cfp, minper;
+	struct mesh_state *ms, **prev_statep;
+	struct Scsi_Host *mesh_host;
+	void *dma_cmd_space;
+
+	nmeshes = 0;
+	prev_statep = &all_meshes;
+	for (mesh = find_devices("mesh"); mesh != 0; mesh = mesh->next) {
+		if (mesh->n_addrs != 2 || mesh->n_intrs != 2)
+			panic("mesh: expected 2 addrs and intrs (got %d/%d)",
+			      mesh->n_addrs, mesh->n_intrs);
+		mesh_host = scsi_register(tp, sizeof(struct mesh_state));
+		if (mesh_host == 0)
+			panic("couldn't register mesh host");
+		mesh_host->unique_id = nmeshes;
+		note_scsi_host(mesh, mesh_host);
+
+		ms = (struct mesh_state *) mesh_host->hostdata;
+		if (ms == 0)
+			panic("no mesh state");
+		memset(ms, 0, sizeof(*ms));
+		ms->host = mesh_host;
+		ms->mesh = (volatile struct mesh_regs *)
+			mesh->addrs[0].address;
+		ms->meshintr = mesh->intrs[0];
+		ms->dma = (volatile struct dbdma_regs *)
+			mesh->addrs[1].address;
+		ms->dmaintr = mesh->intrs[1];
+
+		/* Space for dma command list: +1 for stop command,
+		   +1 to allow for aligning. */
+		dma_cmd_space = kmalloc((mesh_host->sg_tablesize + 2) *
+					sizeof(struct dbdma_cmd), GFP_KERNEL);
+		if (dma_cmd_space == 0)
+			panic("mesh: couldn't allocate dma command space");
+		ms->dma_cmds = (struct dbdma_cmd *) DBDMA_ALIGN(dma_cmd_space);
+		memset(ms->dma_cmds, 0, (mesh_host->sg_tablesize + 1)
+		       * sizeof(struct dbdma_cmd));
+
+		ms->current_req = 0;
+		for (tgt = 0; tgt < 8; ++tgt) {
+			ms->tgts[tgt].sdtr_state = do_sdtr;
+			ms->tgts[tgt].sync_params = ASYNC_PARAMS;
+			ms->tgts[tgt].current_req = 0;
+		}
+
+		ms->tqueue.routine = finish_cmds;
+		ms->tqueue.data = ms;
+
+		*prev_statep = ms;
+		prev_statep = &ms->next;
+
+		if (request_irq(ms->meshintr, mesh_interrupt, 0, "MESH", ms)) {
+			printk(KERN_ERR "MESH: can't get irq %d\n", ms->meshintr);
+		}
+
+		cfp = (int *) get_property(mesh, "clock-frequency", NULL);
+		if (cfp) {
+			ms->clk_freq = *cfp;
+		} else {
+			printk(KERN_INFO "mesh: assuming 50MHz clock frequency\n");
+			ms->clk_freq = 50000000;
+		}
+		/* The maximum sync rate is clock / 5; increase
+		   mesh_sync_period if necessary. */
+		minper = 1000000000 / (ms->clk_freq / 5);	/* ns */
+		if (mesh_sync_period < minper)
+			mesh_sync_period = minper;
+
+		mesh_init(ms);
+
+		++nmeshes;
+	}
+	if (nmeshes > 0)
+		register_reboot_notifier(&mesh_notifier);
+
+	return nmeshes;
+}
+
+int
+mesh_queue(Scsi_Cmnd *cmd, void (*done)(Scsi_Cmnd *))
+{
+	unsigned long flags;
+	struct mesh_state *ms;
+
+#if 0
+	if (data_goes_out(cmd)) {
+		printk(KERN_DEBUG "mesh_queue %p: command is", cmd);
+		for (i = 0; i < cmd->cmd_len; ++i)
+			printk(" %.2x", cmd->cmnd[i]);
+		printk("\n" KERN_DEBUG "use_sg=%d request_bufflen=%d request_buffer=%p\n",
+		       cmd->use_sg, cmd->request_bufflen, cmd->request_buffer);
+	}
+#endif
+
+	cmd->scsi_done = done;
+	cmd->host_scribble = NULL;
+
+	ms = (struct mesh_state *) cmd->host->hostdata;
+
+	save_flags(flags);
+	cli();
+	if (ms->request_q == NULL)
+		ms->request_q = cmd;
+	else
+		ms->request_qtail->host_scribble = (void *) cmd;
+	ms->request_qtail = cmd;
+
+	if (ms->phase == idle)
+		mesh_start(ms);
+
+	restore_flags(flags);
+	return 0;
+}
+
+int
+mesh_abort(Scsi_Cmnd *cmd)
+{
+	printk(KERN_DEBUG "mesh_abort(%p)\n", cmd);
+	mesh_dump_regs((struct mesh_state *)(cmd->host->hostdata));
+	return SCSI_ABORT_SNOOZE;
+}
+
+static void
+mesh_dump_regs(struct mesh_state *ms)
+{
+	volatile struct mesh_regs *mr = ms->mesh;
+	volatile struct dbdma_regs *md = ms->dma;
+	int t;
+	struct mesh_target *tp;
+
+	printk(KERN_DEBUG "mesh: state at %p, regs at %p, dma at %p\n",
+	       ms, mr, md);
+	printk(KERN_DEBUG "    ct=%4x seq=%2x bs=%4x fc=%2x exc=%2x err=%2x sp=%2x\n",
+	       (mr->count_hi << 8) + mr->count_lo, mr->sequence,
+	       (mr->bus_status1 << 8) + mr->bus_status0, mr->fifo_count,
+	       mr->exception, mr->error, mr->sync_params);
+	printk(KERN_DEBUG "    dma stat=%x cmdptr=%x\n",
+	       in_le32(&md->status), in_le32(&md->cmdptr));
+	printk(KERN_DEBUG "    phase=%d msgphase=%d conn_tgt=%d data_ptr=%d\n",
+	       ms->phase, ms->msgphase, ms->conn_tgt, ms->data_ptr);
+	printk(KERN_DEBUG "    goes_out=%d dma_st=%d dma_ct=%d n_msgout=%d\n",
+	       ms->data_goes_out, ms->dma_started, ms->dma_count, ms->n_msgout);
+	for (t = 0; t < 8; ++t) {
+		tp = &ms->tgts[t];
+		if (tp->current_req == NULL)
+			continue;
+		printk(KERN_DEBUG "    target %d: req=%p phase=%d saved_ptr=%d\n",
+		       t, tp->current_req, tp->phase, tp->saved_ptr);
+	}
+}
+
+int
+mesh_reset(Scsi_Cmnd *cmd, unsigned how)
+{
+	struct mesh_state *ms = (struct mesh_state *) cmd->host->hostdata;
+	volatile struct mesh_regs *mr = ms->mesh;
+	volatile struct dbdma_regs *md = ms->dma;
+	unsigned long flags;
+	int ret;
+
+	printk(KERN_DEBUG "mesh_reset %x\n", how);
+	ret = SCSI_RESET_BUS_RESET;
+	save_flags(flags);
+	cli();
+	out_8(&mr->exception, 0xff);	/* clear all exception bits */
+	out_8(&mr->error, 0xff);	/* clear all error bits */
+	out_le32(&md->control, (RUN|PAUSE|FLUSH|WAKE) << 16);
+	if (how & SCSI_RESET_SUGGEST_HOST_RESET) {
+		out_8(&mr->sequence, SEQ_RESETMESH);
+		ret |= SCSI_RESET_HOST_RESET;
+		udelay(1);
+		out_8(&mr->intr_mask, INT_ERROR | INT_EXCEPTION | INT_CMDDONE);
+	}
+	out_8(&mr->bus_status1, BS1_RST);	/* assert RST */
+	udelay(30);			/* leave it on for >= 25us */
+	out_8(&mr->bus_status1, 0);	/* negate RST */
+#ifdef DO_ASYNC_RESET
+	if (how & SCSI_RESET_ASYNCHRONOUS) {
+		restore_flags(flags);
+		ret |= SCSI_RESET_PENDING;
+	} else
+#endif
+	{
+		out_8(&mr->interrupt, INT_ERROR | INT_EXCEPTION | INT_CMDDONE);
+		handle_reset(ms);
+		restore_flags(flags);
+		finish_cmds(ms);
+		ret |= SCSI_RESET_SUCCESS;
+	}
+	return ret;
+}
+
+/*
+ * If we leave drives set for synchronous transfers (especially
+ * CDROMs), and reboot to MacOS, it gets confused, poor thing.
+ * So, on reboot we reset the SCSI bus.
+ */
+static int
+mesh_notify_reboot(struct notifier_block *this, unsigned long code, void *x)
+{
+	struct mesh_state *ms;
+	volatile struct mesh_regs *mr;
+
+	if (code == SYS_DOWN || code == SYS_HALT) {
+		printk(KERN_INFO "resetting MESH scsi bus(es)\n");
+		for (ms = all_meshes; ms != 0; ms = ms->next) {
+			mr = ms->mesh;
+			out_8(&mr->intr_mask, 0);
+			out_8(&mr->interrupt,
+			      INT_ERROR | INT_EXCEPTION | INT_CMDDONE);
+			out_8(&mr->bus_status1, BS1_RST);
+			udelay(30);
+			out_8(&mr->bus_status1, 0);
+		}
+	}
+	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;
+
+	out_8(&mr->interrupt, 0xff);	/* clear all interrupt bits */
+	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);	/* asynchronous initially */
+	out_le32(&md->control, (RUN|PAUSE|FLUSH|WAKE) << 16);
+}
+
+/*
+ * 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;
+	volatile struct mesh_regs *mr = ms->mesh;
+
+	if (ms->phase != idle || ms->current_req != NULL)
+		panic("inappropriate mesh_start (ms=%p)", ms);
+
+	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;
+
+	ms->current_req = cmd;
+	ms->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
+
+	/* Off we go */
+	out_8(&mr->sequence, SEQ_ARBITRATE);
+
+	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;
+}
+
+static void
+finish_cmds(void *data)
+{
+	struct mesh_state *ms = data;
+	Scsi_Cmnd *cmd;
+	unsigned long flags;
+
+	for (;;) {
+		save_flags(flags);
+		cli();
+		cmd = ms->completed_q;
+		if (cmd == NULL) {
+			restore_flags(flags);
+			break;
+		}
+		ms->completed_q = (Scsi_Cmnd *) cmd->host_scribble;
+		restore_flags(flags);
+		(*cmd->scsi_done)(cmd);
+	}
+}
+
+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];
+
+	if (cmd == 0) {
+		printk(KERN_ERR "mesh: start_phase but no cmd?\n");
+		return;
+	}
+	seq = SEQ_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 (DEBUG_TARGET(cmd)) {
+			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");
+		}
+		out_8(&mr->count_hi, 0);
+		if (ms->n_msgout == 1) {
+			out_8(&mr->count_lo, 1);
+			out_8(&mr->sequence, SEQ_MSGOUT + SEQ_ACTIVE_NEG);
+			udelay(1);
+			out_8(&mr->fifo, ms->msgout[0]);
+			ms->msgphase = msg_out_last;
+		} 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, cmd->target);
+		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);
+		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]);
+		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, (ms->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);
+		out_8(&mr->sequence, SEQ_BUSFREE);
+		break;
+	default:
+		printk(KERN_ERR "mesh: start_phase called with phase=%d\n",
+		       ms->phase);
+	}
+
+}
+
+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;
+
+	seq = SEQ_ACTIVE_NEG + (ms->n_msgout? SEQ_ATN: 0);
+	switch (ms->msgphase) {
+	case msg_out_xxx:
+		/* huh?  we expected a phase mismatch */
+		ms->n_msgin = 0;
+		ms->msgphase = msg_in;
+		/* fall through */
+
+	case msg_in:
+		/* should have some message bytes in fifo */
+		get_msgin(ms);
+		n = msgin_length(ms);
+		if (ms->n_msgin < n) {
+			out_8(&mr->count_lo, n - ms->n_msgin);
+			out_8(&mr->sequence, SEQ_MSGIN + seq);
+		} else {
+			ms->msgphase = msg_none;
+			handle_msgin(ms);
+			start_phase(ms);
+		}
+		break;
+
+	case msg_out:
+		/*
+		 * To get the right timing on ATN wrt ACK, we have
+		 * to get the MESH to drop ACK, wait until REQ gets
+		 * asserted, then drop ATN.  To do this we first
+		 * issue a SEQ_MSGOUT with ATN and wait for REQ,
+		 * then change the command to a SEQ_MSGOUT w/o ATN.
+		 * If we don't see REQ in a reasonable time, we
+		 * change the command to SEQ_MSGIN with ATN,
+		 * wait for the phase mismatch interrupt, then
+		 * issue the SEQ_MSGOUT without ATN.
+		 */
+		out_8(&mr->count_lo, 1);
+		out_8(&mr->sequence, SEQ_MSGOUT + SEQ_ACTIVE_NEG + SEQ_ATN);
+		t = 30;		/* wait up to 30us */
+		while ((mr->bus_status0 & BS0_REQ) == 0 && --t >= 0)
+			udelay(1);
+		if (mr->bus_status0 & BS0_REQ) {
+			out_8(&mr->sequence, SEQ_MSGOUT + SEQ_ACTIVE_NEG);
+			udelay(1);
+			out_8(&mr->fifo, ms->msgout[ms->n_msgout-1]);
+			ms->msgphase = msg_out_last;
+		} else {
+			out_8(&mr->sequence, SEQ_MSGIN + SEQ_ACTIVE_NEG + SEQ_ATN);
+			ms->msgphase = msg_out_xxx;
+		}
+		break;
+
+	case msg_out_last:
+		ms->last_n_msgout = ms->n_msgout;
+		ms->n_msgout = 0;
+		ms->msgphase = ms->expect_reply? msg_in: msg_none;
+		start_phase(ms);
+		break;
+
+	case msg_none:
+		switch (ms->phase) {
+		case selecting:
+			ms->msgout[0] = IDENTIFY(ALLOW_RESEL(cmd->target), cmd->lun);
+			ms->n_msgout = 1;
+			ms->expect_reply = 0;
+			if (tp->sdtr_state == do_sdtr) {
+				/* add SDTR message */
+				add_sdtr_msg(ms);
+				ms->expect_reply = 1;
+				tp->sdtr_state = sdtr_sent;
+			}
+			ms->msgphase = msg_out;
+			/*
+			 * We need to wait for REQ before dropping ATN.
+			 * We wait for at most 30us, then fall back to
+			 * a scheme where we issue a SEQ_COMMAND with ATN,
+			 * which will give us a phase mismatch interrupt
+			 * when REQ does come, and then we send the message.
+			 */
+			t = 30;		/* wait up to 30us */
+			while ((mr->bus_status0 & BS0_REQ) == 0) {
+				if (--t < 0) {
+					ms->msgphase = msg_none;
+					break;
+				}
+				udelay(1);
+			}
+			break;
+		case dataing:
+			if (ms->dma_count != 0) {
+				start_phase(ms);
+				return;
+			}
+			halt_dma(ms);
+			break;
+		case statusing:
+			cmd->SCp.Status = mr->fifo;
+			cmd->result = (DID_OK << 16) + cmd->SCp.Status;
+			ms->msgphase = msg_in;
+			if (DEBUG_TARGET(cmd))
+				printk(KERN_DEBUG "mesh: status is %x\n",
+				       cmd->SCp.Status);
+			break;
+		case busfreeing:
+			mesh_done(ms);
+			return;
+		case disconnecting:
+			ms->current_req = 0;
+			ms->phase = idle;
+			mesh_start(ms);
+			return;
+		default:
+			break;
+		}
+		++ms->phase;
+		start_phase(ms);
+		break;
+	}
+}
+
+static void phase_mismatch(struct mesh_state *ms)
+{
+	volatile struct mesh_regs *mr = ms->mesh;
+	int phase;
+
+	phase = mr->bus_status0 & BS0_PHASE;
+	if (ms->msgphase == msg_out_xxx && phase == BP_MSGOUT) {
+		/* output the last byte of the message, without ATN */
+		out_8(&mr->count_lo, 1);
+		out_8(&mr->sequence, SEQ_MSGOUT + SEQ_ACTIVE_NEG);
+		udelay(1);
+		out_8(&mr->fifo, ms->msgout[ms->n_msgout-1]);
+		ms->msgphase = msg_out_last;
+		return;
+	}
+
+	if (ms->msgphase == msg_in) {
+		get_msgin(ms);
+		if (ms->n_msgin)
+			handle_msgin(ms);
+	}
+
+	if (ms->dma_started)
+		halt_dma(ms);
+	if (mr->fifo_count) {
+		out_8(&mr->sequence, SEQ_FLUSHFIFO);
+		udelay(1);
+	}
+
+	ms->msgphase = msg_none;
+	switch (phase) {
+	case BP_DATAIN:
+		ms->data_goes_out = 0;
+		ms->phase = dataing;
+		break;
+	case BP_DATAOUT:
+		ms->data_goes_out = 1;
+		ms->phase = dataing;
+		break;
+	case BP_COMMAND:
+		ms->phase = commanding;
+		break;
+	case BP_STATUS:
+		ms->phase = statusing;
+		break;
+	case BP_MSGIN:
+		ms->msgphase = msg_in;
+		ms->n_msgin = 0;
+		break;
+	case BP_MSGOUT:
+		ms->msgphase = msg_out;
+		if (ms->n_msgout == 0) {
+			if (ms->last_n_msgout == 0) {
+				printk(KERN_DEBUG "mesh: no msg to repeat\n");
+				ms->msgout[0] = NOP;
+				ms->last_n_msgout = 1;
+			}
+			ms->n_msgout = ms->last_n_msgout;
+		}
+		break;
+	default:
+		printk(KERN_DEBUG "mesh: unknown scsi phase %x\n", phase);
+		ms->current_req->result = DID_ERROR << 16;
+		mesh_done(ms);
+		return;
+	}
+
+	start_phase(ms);
+}
+
+static void
+reselected(struct mesh_state *ms)
+{
+	volatile struct mesh_regs *mr = ms->mesh;
+	Scsi_Cmnd *cmd = ms->current_req;
+	struct mesh_target *tp;
+	int b, t;
+
+	switch (ms->phase) {
+	case idle:
+	case arbitrating:
+		break;
+	case busfreeing:
+		ms->phase = reselecting;
+		mesh_done(ms);
+		cmd = NULL;
+		break;
+	case disconnecting:
+		cmd = NULL;
+		break;
+	default:
+		printk(KERN_ERR "mesh: reselected in phase %d/%d\n",
+		       ms->msgphase, ms->phase);
+	}
+	if (cmd) {
+		/* put the command back on the queue */
+		cmd->host_scribble = (void *) ms->request_q;
+		if (ms->request_q == NULL)
+			ms->request_qtail = cmd;
+		ms->request_q = cmd;
+		tp = &ms->tgts[cmd->target];
+		tp->current_req = NULL;
+		ms->current_req = NULL;
+	}
+
+	/*
+	 * Find out who reselected us.
+	 */
+	if (mr->fifo_count == 0) {
+		printk(KERN_ERR "mesh: reselection but nothing in fifo?\n");
+		return;
+	}
+	/* get the last byte in the fifo */
+	do {
+		b = in_8(&mr->fifo);
+	} while (in_8(&mr->fifo_count));
+	for (t = 0; t < 8; ++t)
+		if ((b & (1 << t)) != 0 && t != ms->host->this_id)
+			break;
+	if (b != (1 << t) + (1 << ms->host->this_id)) {
+		printk(KERN_ERR "mesh: bad reselection data %x\n", b);
+		return;
+	}
+
+	/*
+	 * Set up to continue with that target's transfer.
+	 */
+	tp = &ms->tgts[t];
+	if (ALLOW_DEBUG(t)) {
+		printk(KERN_DEBUG "mesh: reselected by target %d\n", t);
+		printk(KERN_DEBUG "mesh: saved_ptr=%x phase=%d cmd=%p\n",
+		       tp->saved_ptr, tp->phase, tp->current_req);
+	}
+	if (tp->current_req == NULL) {
+		printk(KERN_ERR "mesh: reselected by tgt %d but no cmd!\n", t);
+		return;
+	}
+	ms->current_req = tp->current_req;
+	ms->phase = tp->phase;
+	ms->msgphase = msg_in;
+	ms->data_goes_out = tp->data_goes_out;
+	ms->data_ptr = tp->saved_ptr;
+	ms->conn_tgt = t;
+	ms->dma_started = 0;
+	ms->n_msgout = 0;
+	ms->last_n_msgout = 0;
+	out_8(&mr->sync_params, tp->sync_params);
+	start_phase(ms);
+}
+
+static void
+handle_reset(struct mesh_state *ms)
+{
+	int tgt;
+	struct mesh_target *tp;
+	Scsi_Cmnd *cmd;
+	volatile struct mesh_regs *mr = ms->mesh;
+
+	for (tgt = 0; tgt < 8; ++tgt) {
+		tp = &ms->tgts[tgt];
+		if ((cmd = tp->current_req) != NULL) {
+			cmd->result = DID_RESET << 16;
+			tp->current_req = NULL;
+			mesh_completed(ms, cmd);
+		}
+		ms->tgts[tgt].sdtr_state = do_sdtr;
+		ms->tgts[tgt].sync_params = ASYNC_PARAMS;
+	}
+	ms->current_req = NULL;
+	while ((cmd = ms->request_q) != NULL) {
+		ms->request_q = (Scsi_Cmnd *) cmd->host_scribble;
+		cmd->result = DID_RESET << 16;
+		mesh_completed(ms, cmd);
+	}
+	ms->phase = idle;
+	out_8(&mr->sync_params, ASYNC_PARAMS);
+}
+
+static void
+mesh_interrupt(int irq, void *dev_id, struct pt_regs *ptregs)
+{
+	struct mesh_state *ms = (struct mesh_state *) dev_id;
+	volatile struct mesh_regs *mr = ms->mesh;
+	Scsi_Cmnd *cmd = ms->current_req;
+	int stat, exc, err, intr;
+
+#if 0
+	if (DEBUG_TARGET(cmd))
+		printk(KERN_DEBUG "mesh_intr, bs0=%x int=%x exc=%x err=%x phase=%d msgphase=%d\n",
+		       mr->bus_status0, mr->interrupt, mr->exception, mr->error, ms->phase, ms->msgphase);
+#endif
+	while ((intr = in_8(&mr->interrupt)) != 0) {
+		if (intr & INT_ERROR) {
+			stat = DID_BAD_INTR << 16;
+			err = in_8(&mr->error);
+			exc = in_8(&mr->exception);
+			out_8(&mr->interrupt, INT_ERROR | INT_EXCEPTION | INT_CMDDONE);
+			if (err & ERR_SCSIRESET) {
+				/* SCSI bus was reset */
+				printk(KERN_INFO "mesh: SCSI bus reset detected: "
+				       "waiting for end...");
+				while ((mr->bus_status1 & BS1_RST) != 0)
+					udelay(1);
+				printk("done\n");
+				handle_reset(ms);
+				/* request_q is empty, no point in mesh_start() */
+				continue;
+			} else if (err & ERR_UNEXPDISC) {
+				/* Unexpected disconnect */
+				printk(KERN_WARNING "mesh: target %d aborted\n",
+				       ms->conn_tgt);
+				stat = DID_ABORT << 16;
+			} else if (err & ERR_PARITY) {
+				printk(KERN_ERR "mesh: parity error\n");
+				stat = DID_PARITY << 16;
+			} else if ((err & ERR_SEQERR) && (exc & EXC_RESELECTED)
+				   && ms->phase == arbitrating) {
+				/* This can happen if we issue a command to
+				   get the bus just after the target
+				   reselects us. */
+				static int mesh_resel_seqerr;
+				mesh_resel_seqerr++;
+				reselected(ms);
+				continue;
+			} else {
+				printk(KERN_ERR "mesh: error %x (exc = %x)\n",
+				       err, exc);
+				mesh_dump_regs(ms);
+			}
+			if (cmd != 0) {
+				cmd->result = stat;
+				mesh_done(ms);
+			}
+
+		} else if (intr & INT_EXCEPTION) {
+			exc = in_8(&mr->exception);
+			out_8(&mr->interrupt, INT_EXCEPTION | INT_CMDDONE);
+			if (exc & EXC_RESELECTED) {
+				static int mesh_resel_exc;
+				mesh_resel_exc++;
+				reselected(ms);
+			} else if (cmd && exc == EXC_ARBLOST
+				   && ms->phase == arbitrating) {
+				printk(KERN_DEBUG "mesh: lost arbitration\n");
+				cmd->result = DID_BUS_BUSY << 16;
+				mesh_done(ms);
+			} else if (cmd && exc == EXC_SELTO && ms->phase == selecting) {
+				/* selection timed out */
+				cmd->result = DID_BAD_TARGET << 16;
+				mesh_done(ms);
+			} else if (cmd && exc == EXC_PHASEMM
+				   && (mr->bus_status0 & BS0_REQ) != 0) {
+				/* target wants to do something different:
+			   find out what it wants and do it. */
+				phase_mismatch(ms);
+			} else {
+				printk(KERN_ERR "mesh: can't cope with exception %x\n",
+				       exc);
+				cmd->result = DID_ERROR << 16;
+				mesh_done(ms);
+			}
+
+		} else if (intr & INT_CMDDONE) {
+			out_8(&mr->interrupt, INT_CMDDONE);
+			cmd_complete(ms);
+		}
+	}
+}
+
+static void
+handle_msgin(struct mesh_state *ms)
+{
+	int i;
+	Scsi_Cmnd *cmd = ms->current_req;
+	struct mesh_target *tp = &ms->tgts[ms->conn_tgt];
+
+	if (ms->n_msgin == 0)
+		return;
+	if (DEBUG_TARGET(cmd)) {
+		printk(KERN_DEBUG "got %d message bytes:", ms->n_msgin);
+		for (i = 0; i < ms->n_msgin; ++i)
+			printk(" %x", ms->msgin[i]);
+		printk("\n");
+	}
+
+	ms->expect_reply = 0;
+	ms->n_msgout = 0;
+	if (ms->n_msgin < msgin_length(ms))
+		goto reject;
+	if (cmd)
+		cmd->SCp.Message = ms->msgin[0];
+	switch (ms->msgin[0]) {
+	case COMMAND_COMPLETE:
+		break;
+	case EXTENDED_MESSAGE:
+		switch (ms->msgin[2]) {
+		case EXTENDED_MODIFY_DATA_POINTER:
+			ms->data_ptr += (ms->msgin[3] << 24) + ms->msgin[6]
+				+ (ms->msgin[4] << 16) + (ms->msgin[5] << 8);
+			break;
+		case EXTENDED_SDTR:
+			if (tp->sdtr_state != sdtr_sent) {
+				/* reply with an SDTR */
+				add_sdtr_msg(ms);
+				/* limit period to at least his value,
+				   offset to no more than his */
+				if (ms->msgout[3] < ms->msgin[3])
+					ms->msgout[3] = ms->msgin[3];
+				if (ms->msgout[4] > ms->msgin[4])
+					ms->msgout[4] = ms->msgin[4];
+				set_sdtr(ms, ms->msgout[3], ms->msgout[4]);
+				ms->msgphase = msg_out;
+			} else {
+				set_sdtr(ms, ms->msgin[3], ms->msgin[4]);
+			}
+			break;
+		default:
+			goto reject;
+		}
+		break;
+	case SAVE_POINTERS:
+		tp->saved_ptr = ms->data_ptr;
+		break;
+	case RESTORE_POINTERS:
+		ms->data_ptr = tp->saved_ptr;
+		break;
+	case DISCONNECT:
+		tp->phase = ms->phase;
+		tp->data_goes_out = ms->data_goes_out;
+		ms->phase = disconnecting;
+		break;
+	case ABORT:
+		break;
+	case MESSAGE_REJECT:
+		if (tp->sdtr_state == sdtr_sent)
+			set_sdtr(ms, 0, 0);
+		break;
+	case NOP:
+		break;
+	default:
+		if (cmd && IDENTIFY_BASE <= ms->msgin[0]
+		    && ms->msgin[0] <= IDENTIFY_BASE + 7) {
+			i = ms->msgin[0] - IDENTIFY_BASE;
+			if (i != cmd->lun)
+				printk(KERN_WARNING "mesh: lun mismatch "
+				       "(%d != %d) on reselection from "
+				       "target %d\n", i, cmd->lun,
+				       ms->conn_tgt);
+			break;
+		}
+		goto reject;
+	}
+	return;
+
+ reject:
+	printk(KERN_WARNING "mesh: rejecting message %x from target %d\n",
+	       ms->msgin[0], ms->conn_tgt);
+	ms->msgout[0] = MESSAGE_REJECT;
+	ms->n_msgout = 1;
+	ms->msgphase = msg_out;
+}
+
+static void
+mesh_done(struct mesh_state *ms)
+{
+	Scsi_Cmnd *cmd;
+	struct mesh_target *tp = &ms->tgts[ms->conn_tgt];
+
+	cmd = ms->current_req;
+	if (DEBUG_TARGET(cmd)) {
+		printk(KERN_DEBUG "mesh_done: result = %x, data_ptr=%d, buflen=%d\n",
+		       cmd->result, ms->data_ptr, cmd->request_bufflen);
+		if ((cmd->cmnd[0] == 0 || cmd->cmnd[0] == 0x12 || cmd->cmnd[0] == 3)
+		    && cmd->request_buffer != 0) {
+			unsigned char *b = cmd->request_buffer;
+			printk(KERN_DEBUG "buffer = %x %x %x %x %x %x %x %x\n",
+			       b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7]);
+		}
+	}
+	tp->current_req = 0;
+	cmd->SCp.this_residual -= ms->data_ptr;
+	ms->current_req = NULL;
+	mesh_completed(ms, cmd);
+	if (ms->phase != reselecting) {
+		ms->phase = idle;
+		mesh_start(ms);
+	}
+}
+
+static void
+mesh_completed(struct mesh_state *ms, Scsi_Cmnd *cmd)
+{
+	if (ms->completed_q == NULL)
+		ms->completed_q = cmd;
+	else
+		ms->completed_qtail->host_scribble = (void *) cmd;
+	ms->completed_qtail = cmd;
+	cmd->host_scribble = NULL;
+	queue_task(&ms->tqueue, &tq_immediate);
+	mark_bh(IMMEDIATE_BH);
+}
+
+/*
+ * Set up DMA commands for transferring data.
+ */
+static void
+set_dma_cmds(struct mesh_state *ms, Scsi_Cmnd *cmd)
+{
+	int i, dma_cmd, total, off, dtot;
+	struct scatterlist *scl;
+	struct dbdma_cmd *dcmds;
+
+	dma_cmd = ms->data_goes_out? OUTPUT_MORE: INPUT_MORE;
+	dcmds = ms->dma_cmds;
+	dtot = 0;
+	cmd->SCp.this_residual = cmd->request_bufflen;
+	if (cmd->use_sg > 0) {
+		total = 0;
+		scl = (struct scatterlist *) cmd->buffer;
+		off = ms->data_ptr;
+		for (i = 0; i < cmd->use_sg; ++i, ++scl) {
+			total += scl->length;
+			if (off >= scl->length) {
+				off -= scl->length;
+				continue;
+			}
+			if (scl->length > 0xffff)
+				panic("mesh: scatterlist element >= 64k");
+			st_le16(&dcmds->req_count, scl->length - off);
+			st_le16(&dcmds->command, dma_cmd);
+			st_le32(&dcmds->phy_addr,
+				virt_to_phys(scl->address) + off);
+			dcmds->xfer_status = 0;
+			++dcmds;
+			dtot += scl->length - off;
+			off = 0;
+		}
+	} else if (ms->data_ptr < cmd->request_bufflen) {
+		dtot = cmd->request_bufflen - ms->data_ptr;
+		if (dtot > 0xffff)
+			panic("mesh: transfer size >= 64k");
+		st_le16(&dcmds->req_count, dtot);
+		st_le32(&dcmds->phy_addr,
+			virt_to_phys(cmd->request_buffer) + ms->data_ptr);
+		dcmds->xfer_status = 0;
+		++dcmds;
+	}
+	if (dtot == 0) {
+		/* Either the target has overrun our buffer,
+		   or the caller didn't provide a buffer. */
+		static char mesh_extra_buf[64];
+
+		if (cmd->request_bufflen != 0)
+			printk(KERN_DEBUG "mesh: target %d overrun, "
+			       "data_ptr=%x total=%x goes_out=%d\n",
+			       ms->conn_tgt, ms->data_ptr,
+			       cmd->request_bufflen, ms->data_goes_out);
+		dtot = sizeof(mesh_extra_buf);
+		st_le16(&dcmds->req_count, dtot);
+		st_le32(&dcmds->phy_addr, virt_to_phys(mesh_extra_buf));
+		dcmds->xfer_status = 0;
+		++dcmds;
+	}
+	dma_cmd += OUTPUT_LAST - OUTPUT_MORE;
+	st_le16(&dcmds[-1].command, dma_cmd);
+	memset(dcmds, 0, sizeof(*dcmds));
+	st_le16(&dcmds->command, DBDMA_STOP);
+	ms->dma_count = dtot;
+}
+
+static void
+halt_dma(struct mesh_state *ms)
+{
+	volatile struct dbdma_regs *md = ms->dma;
+	volatile struct mesh_regs *mr = ms->mesh;
+	int t, nb;
+
+	if (!ms->data_goes_out) {
+		/* wait a little while until the fifo drains */
+		t = 50;
+		while (t > 0 && mr->fifo_count != 0
+		       && (in_le32(&md->status) & ACTIVE) != 0) {
+			--t;
+			udelay(1);
+		}
+	}
+	out_le32(&md->control, RUN << 16);	/* turn off RUN bit */
+	nb = (mr->count_hi << 8) + mr->count_lo;
+	if (ms->data_goes_out)
+		nb += mr->fifo_count;
+	/* nb is the number of bytes not yet transferred
+	   to/from the target. */
+	ms->data_ptr -= nb;
+	if (ms->data_ptr < 0) {
+		printk(KERN_ERR "mesh: halt_dma: data_ptr=%d (nb=%d, ms=%p)\n",
+		       ms->data_ptr, nb, ms);
+		ms->data_ptr = 0;
+	}
+	ms->dma_started = 0;
+}
+
+/*
+ * Work out whether we expect data to go out from the host adaptor or into it.
+ * (If this information is available from somewhere else in the scsi
+ * code, somebody please let me know :-)
+ */
+static int
+data_goes_out(Scsi_Cmnd *cmd)
+{
+	switch (cmd->cmnd[0]) {
+	case MODE_SELECT:
+	case MODE_SELECT_10:
+	case WRITE_6:
+	case WRITE_10:
+	case WRITE_12:		/* any others? */
+		return 1;
+	default:
+		return 0;
+	}
+}