vme: Adding Fake VME driver

This patch introduces a fake VME bridge driver. This driver currently
emulates a subset of the VME bridge functionality. This allows some VME
subsystem development and even some VME device driver development to be
carried out in the absence of a proper VME bus.

Signed-off-by: Martyn Welch <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/vme/bridges/Kconfig

···
 	help
 	 If you say Y here you get support for the Tundra TSI148 VME bridge
 	 chip.
+
+config VME_FAKE
+	tristate "Fake"
+	help
+	 If you say Y here you get support for the fake VME bridge. This
+	 provides a virtualised VME Bus for devices with no VME bridge. This
+	 is mainly useful for VME development (in the absence of VME
+	 hardware).

drivers/vme/bridges/Makefile

···
 obj-$(CONFIG_VME_CA91CX42)	+= vme_ca91cx42.o
 obj-$(CONFIG_VME_TSI148)	+= vme_tsi148.o
+obj-$(CONFIG_VME_FAKE)		+= vme_fake.o

drivers/vme/bridges/vme_fake.c

···
+/*
+ * Fake VME bridge support.
+ *
+ * This drive provides a fake VME bridge chip, this enables debugging of the
+ * VME framework in the absence of a VME system.
+ *
+ * This driver has to do a number of things in software that would be driven
+ * by hardware if it was available, it will also result in extra overhead at
+ * times when compared with driving actual hardware.
+ *
+ * Author: Martyn Welch <[e-mail]>
+ * Copyright (c) 2014 Martyn Welch
+ *
+ * Based on vme_tsi148.c:
+ *
+ * Author: Martyn Welch <[e-mail]>
+ * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
+ *
+ * Based on work by Tom Armistead and Ajit Prem
+ * Copyright 2004 Motorola Inc.
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/vme.h>
+
+#include "../vme_bridge.h"
+
+/*
+ *  Define the number of each that the fake driver supports.
+ */
+#define FAKE_MAX_MASTER		8	/* Max Master Windows */
+#define FAKE_MAX_SLAVE		8	/* Max Slave Windows */
+
+/* Structures to hold information normally held in device registers */
+struct fake_slave_window {
+	int enabled;
+	unsigned long long vme_base;
+	unsigned long long size;
+	dma_addr_t buf_base;
+	u32 aspace;
+	u32 cycle;
+};
+
+struct fake_master_window {
+	int enabled;
+	unsigned long long vme_base;
+	unsigned long long size;
+	u32 aspace;
+	u32 cycle;
+	u32 dwidth;
+};
+
+/* Structure used to hold driver specific information */
+struct fake_driver {
+	struct vme_bridge *parent;
+	struct fake_slave_window slaves[FAKE_MAX_SLAVE];
+	struct fake_master_window masters[FAKE_MAX_MASTER];
+	u32 lm_enabled;
+	unsigned long long lm_base;
+	u32 lm_aspace;
+	u32 lm_cycle;
+	void (*lm_callback[4])(void *);
+	void *lm_data[4];
+	struct tasklet_struct int_tasklet;
+	int int_level;
+	int int_statid;
+	void *crcsr_kernel;
+	dma_addr_t crcsr_bus;
+	/* Only one VME interrupt can be generated at a time, provide locking */
+	struct mutex vme_int;
+};
+
+/* Module parameter */
+static int geoid;
+
+static const char driver_name[] = "vme_fake";
+
+static struct vme_bridge *exit_pointer;
+
+static struct device *vme_root;
+
+/*
+ * Calling VME bus interrupt callback if provided.
+ */
+static void fake_VIRQ_tasklet(unsigned long data)
+{
+	struct vme_bridge *fake_bridge;
+	struct fake_driver *bridge;
+
+	fake_bridge = (struct vme_bridge *) data;
+	bridge = fake_bridge->driver_priv;
+
+	vme_irq_handler(fake_bridge, bridge->int_level, bridge->int_statid);
+}
+
+/*
+ * Configure VME interrupt
+ */
+static void fake_irq_set(struct vme_bridge *fake_bridge, int level,
+		int state, int sync)
+{
+	/* Nothing to do */
+}
+
+/*
+ * Generate a VME bus interrupt at the requested level & vector. Wait for
+ * interrupt to be acked.
+ */
+static int fake_irq_generate(struct vme_bridge *fake_bridge, int level,
+		int statid)
+{
+	struct fake_driver *bridge;
+
+	bridge = fake_bridge->driver_priv;
+
+	mutex_lock(&bridge->vme_int);
+
+	bridge->int_level = level;
+
+	bridge->int_statid = statid;
+
+	/*
+	 * Schedule tasklet to run VME handler to emulate normal VME interrupt
+	 * handler behaviour.
+	 */
+	tasklet_schedule(&bridge->int_tasklet);
+
+	mutex_unlock(&bridge->vme_int);
+
+	return 0;
+}
+
+/*
+ * Initialize a slave window with the requested attributes.
+ */
+static int fake_slave_set(struct vme_slave_resource *image, int enabled,
+		unsigned long long vme_base, unsigned long long size,
+		dma_addr_t buf_base, u32 aspace, u32 cycle)
+{
+	unsigned int i, granularity = 0;
+	unsigned long long vme_bound;
+	struct vme_bridge *fake_bridge;
+	struct fake_driver *bridge;
+
+	fake_bridge = image->parent;
+	bridge = fake_bridge->driver_priv;
+
+	i = image->number;
+
+	switch (aspace) {
+	case VME_A16:
+		granularity = 0x10;
+		break;
+	case VME_A24:
+		granularity = 0x1000;
+		break;
+	case VME_A32:
+		granularity = 0x10000;
+		break;
+	case VME_A64:
+		granularity = 0x10000;
+		break;
+	case VME_CRCSR:
+	case VME_USER1:
+	case VME_USER2:
+	case VME_USER3:
+	case VME_USER4:
+	default:
+		pr_err("Invalid address space\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Bound address is a valid address for the window, adjust
+	 * accordingly
+	 */
+	vme_bound = vme_base + size - granularity;
+
+	if (vme_base & (granularity - 1)) {
+		pr_err("Invalid VME base alignment\n");
+		return -EINVAL;
+	}
+	if (vme_bound & (granularity - 1)) {
+		pr_err("Invalid VME bound alignment\n");
+		return -EINVAL;
+	}
+
+	mutex_lock(&image->mtx);
+
+	bridge->slaves[i].enabled = enabled;
+	bridge->slaves[i].vme_base = vme_base;
+	bridge->slaves[i].size = size;
+	bridge->slaves[i].buf_base = buf_base;
+	bridge->slaves[i].aspace = aspace;
+	bridge->slaves[i].cycle = cycle;
+
+	mutex_unlock(&image->mtx);
+
+	return 0;
+}
+
+/*
+ * Get slave window configuration.
+ */
+static int fake_slave_get(struct vme_slave_resource *image, int *enabled,
+		unsigned long long *vme_base, unsigned long long *size,
+		dma_addr_t *buf_base, u32 *aspace, u32 *cycle)
+{
+	unsigned int i;
+	struct fake_driver *bridge;
+
+	bridge = image->parent->driver_priv;
+
+	i = image->number;
+
+	mutex_lock(&image->mtx);
+
+	*enabled = bridge->slaves[i].enabled;
+	*vme_base = bridge->slaves[i].vme_base;
+	*size = bridge->slaves[i].size;
+	*buf_base = bridge->slaves[i].buf_base;
+	*aspace = bridge->slaves[i].aspace;
+	*cycle = bridge->slaves[i].cycle;
+
+	mutex_unlock(&image->mtx);
+
+	return 0;
+}
+
+/*
+ * Set the attributes of an outbound window.
+ */
+static int fake_master_set(struct vme_master_resource *image, int enabled,
+		unsigned long long vme_base, unsigned long long size,
+		u32 aspace, u32 cycle, u32 dwidth)
+{
+	int retval = 0;
+	unsigned int i;
+	struct vme_bridge *fake_bridge;
+	struct fake_driver *bridge;
+
+	fake_bridge = image->parent;
+
+	bridge = fake_bridge->driver_priv;
+
+	/* Verify input data */
+	if (vme_base & 0xFFFF) {
+		pr_err("Invalid VME Window alignment\n");
+		retval = -EINVAL;
+		goto err_window;
+	}
+
+	if (size & 0xFFFF) {
+		spin_unlock(&image->lock);
+		pr_err("Invalid size alignment\n");
+		retval = -EINVAL;
+		goto err_window;
+	}
+
+	if ((size == 0) && (enabled != 0)) {
+		pr_err("Size must be non-zero for enabled windows\n");
+		retval = -EINVAL;
+		goto err_window;
+	}
+
+	/* Setup data width */
+	switch (dwidth) {
+	case VME_D8:
+	case VME_D16:
+	case VME_D32:
+		break;
+	default:
+		spin_unlock(&image->lock);
+		pr_err("Invalid data width\n");
+		retval = -EINVAL;
+		goto err_dwidth;
+	}
+
+	/* Setup address space */
+	switch (aspace) {
+	case VME_A16:
+	case VME_A24:
+	case VME_A32:
+	case VME_A64:
+	case VME_CRCSR:
+	case VME_USER1:
+	case VME_USER2:
+	case VME_USER3:
+	case VME_USER4:
+		break;
+	default:
+		spin_unlock(&image->lock);
+		pr_err("Invalid address space\n");
+		retval = -EINVAL;
+		goto err_aspace;
+	}
+
+	spin_lock(&image->lock);
+
+	i = image->number;
+
+	bridge->masters[i].enabled = enabled;
+	bridge->masters[i].vme_base = vme_base;
+	bridge->masters[i].size = size;
+	bridge->masters[i].aspace = aspace;
+	bridge->masters[i].cycle = cycle;
+	bridge->masters[i].dwidth = dwidth;
+
+	spin_unlock(&image->lock);
+
+	return 0;
+
+err_aspace:
+err_dwidth:
+err_window:
+	return retval;
+
+}
+
+/*
+ * Set the attributes of an outbound window.
+ */
+static int __fake_master_get(struct vme_master_resource *image, int *enabled,
+		unsigned long long *vme_base, unsigned long long *size,
+		u32 *aspace, u32 *cycle, u32 *dwidth)
+{
+	unsigned int i;
+	struct fake_driver *bridge;
+
+	bridge = image->parent->driver_priv;
+
+	i = image->number;
+
+	*enabled = bridge->masters[i].enabled;
+	*vme_base = bridge->masters[i].vme_base;
+	*size = bridge->masters[i].size;
+	*aspace = bridge->masters[i].aspace;
+	*cycle = bridge->masters[i].cycle;
+	*dwidth = bridge->masters[i].dwidth;
+
+	return 0;
+}
+
+
+static int fake_master_get(struct vme_master_resource *image, int *enabled,
+		unsigned long long *vme_base, unsigned long long *size,
+		u32 *aspace, u32 *cycle, u32 *dwidth)
+{
+	int retval;
+
+	spin_lock(&image->lock);
+
+	retval = __fake_master_get(image, enabled, vme_base, size, aspace,
+			cycle, dwidth);
+
+	spin_unlock(&image->lock);
+
+	return retval;
+}
+
+
+void fake_lm_check(struct fake_driver *bridge, unsigned long long addr,
+		u32 aspace, u32 cycle)
+{
+	struct vme_bridge *fake_bridge;
+	unsigned long long lm_base;
+	u32 lm_aspace, lm_cycle;
+	int i;
+	struct vme_lm_resource *lm;
+	struct list_head *pos = NULL, *n;
+
+	/* Get vme_bridge */
+	fake_bridge = bridge->parent;
+
+	/* Loop through each location monitor resource */
+	list_for_each_safe(pos, n, &fake_bridge->lm_resources) {
+		lm = list_entry(pos, struct vme_lm_resource, list);
+
+		/* If disabled, we're done */
+		if (bridge->lm_enabled == 0)
+			return;
+
+		lm_base = bridge->lm_base;
+		lm_aspace = bridge->lm_aspace;
+		lm_cycle = bridge->lm_cycle;
+
+		/* First make sure that the cycle and address space match */
+		if ((lm_aspace == aspace) && (lm_cycle == cycle)) {
+			for (i = 0; i < lm->monitors; i++) {
+				/* Each location monitor covers 8 bytes */
+				if (((lm_base + (8 * i)) <= addr) &&
+				    ((lm_base + (8 * i) + 8) > addr)) {
+					if (bridge->lm_callback[i] != NULL)
+						bridge->lm_callback[i](
+							bridge->lm_data[i]);
+				}
+			}
+		}
+	}
+}
+
+static u8 fake_vmeread8(struct fake_driver *bridge, unsigned long long addr,
+		u32 aspace, u32 cycle)
+{
+	u8 retval = 0xff;
+	int i;
+	unsigned long long start, end, offset;
+	u8 *loc;
+
+	for (i = 0; i < FAKE_MAX_SLAVE; i++) {
+		start = bridge->slaves[i].vme_base;
+		end = bridge->slaves[i].vme_base + bridge->slaves[i].size;
+
+		if (aspace != bridge->slaves[i].aspace)
+			continue;
+
+		if (cycle != bridge->slaves[i].cycle)
+			continue;
+
+		if ((addr >= start) && (addr < end)) {
+			offset = addr - bridge->slaves[i].vme_base;
+			loc = (u8 *)((void *)bridge->slaves[i].buf_base + offset);
+			retval = *loc;
+
+			break;
+		}
+	}
+
+	fake_lm_check(bridge, addr, aspace, cycle);
+
+	return retval;
+}
+
+static u16 fake_vmeread16(struct fake_driver *bridge, unsigned long long addr,
+		u32 aspace, u32 cycle)
+{
+	u16 retval = 0xffff;
+	int i;
+	unsigned long long start, end, offset;
+	u16 *loc;
+
+	for (i = 0; i < FAKE_MAX_SLAVE; i++) {
+		if (aspace != bridge->slaves[i].aspace)
+			continue;
+
+		if (cycle != bridge->slaves[i].cycle)
+			continue;
+
+		start = bridge->slaves[i].vme_base;
+		end = bridge->slaves[i].vme_base + bridge->slaves[i].size;
+
+		if ((addr >= start) && ((addr + 1) < end)) {
+			offset = addr - bridge->slaves[i].vme_base;
+			loc = (u16 *)((void *)bridge->slaves[i].buf_base + offset);
+			retval = *loc;
+
+			break;
+		}
+	}
+
+	fake_lm_check(bridge, addr, aspace, cycle);
+
+	return retval;
+}
+
+static u32 fake_vmeread32(struct fake_driver *bridge, unsigned long long addr,
+		u32 aspace, u32 cycle)
+{
+	u32 retval = 0xffffffff;
+	int i;
+	unsigned long long start, end, offset;
+	u32 *loc;
+
+	for (i = 0; i < FAKE_MAX_SLAVE; i++) {
+		if (aspace != bridge->slaves[i].aspace)
+			continue;
+
+		if (cycle != bridge->slaves[i].cycle)
+			continue;
+
+		start = bridge->slaves[i].vme_base;
+		end = bridge->slaves[i].vme_base + bridge->slaves[i].size;
+
+		if ((addr >= start) && ((addr + 3) < end)) {
+			offset = addr - bridge->slaves[i].vme_base;
+			loc = (u32 *)((void *)bridge->slaves[i].buf_base + offset);
+			retval = *loc;
+
+			break;
+		}
+	}
+
+	fake_lm_check(bridge, addr, aspace, cycle);
+
+	return retval;
+}
+
+static ssize_t fake_master_read(struct vme_master_resource *image, void *buf,
+		size_t count, loff_t offset)
+{
+	int retval;
+	u32 aspace, cycle, dwidth;
+	struct vme_bridge *fake_bridge;
+	struct fake_driver *priv;
+	int i;
+	unsigned long long addr;
+	unsigned int done = 0;
+	unsigned int count32;
+
+	fake_bridge = image->parent;
+
+	priv = fake_bridge->driver_priv;
+
+	i = image->number;
+
+	addr = (unsigned long long)priv->masters[i].vme_base + offset;
+	aspace = priv->masters[i].aspace;
+	cycle = priv->masters[i].cycle;
+	dwidth = priv->masters[i].dwidth;
+
+	spin_lock(&image->lock);
+
+	/* The following code handles VME address alignment. We cannot use
+	 * memcpy_xxx here because it may cut data transfers in to 8-bit
+	 * cycles when D16 or D32 cycles are required on the VME bus.
+	 * On the other hand, the bridge itself assures that the maximum data
+	 * cycle configured for the transfer is used and splits it
+	 * automatically for non-aligned addresses, so we don't want the
+	 * overhead of needlessly forcing small transfers for the entire cycle.
+	 */
+	if (addr & 0x1) {
+		*(u8 *)buf = fake_vmeread8(priv, addr, aspace, cycle);
+		done += 1;
+		if (done == count)
+			goto out;
+	}
+	if ((dwidth == VME_D16) || (dwidth == VME_D32)) {
+		if ((addr + done) & 0x2) {
+			if ((count - done) < 2) {
+				*(u8 *)(buf + done) = fake_vmeread8(priv,
+						addr + done, aspace, cycle);
+				done += 1;
+				goto out;
+			} else {
+				*(u16 *)(buf + done) = fake_vmeread16(priv,
+						addr + done, aspace, cycle);
+				done += 2;
+			}
+		}
+	}
+
+	if (dwidth == VME_D32) {
+		count32 = (count - done) & ~0x3;
+		while (done < count32) {
+			*(u32 *)(buf + done) = fake_vmeread32(priv, addr + done,
+					aspace, cycle);
+			done += 4;
+		}
+	} else if (dwidth == VME_D16) {
+		count32 = (count - done) & ~0x3;
+		while (done < count32) {
+			*(u16 *)(buf + done) = fake_vmeread16(priv, addr + done,
+					aspace, cycle);
+			done += 2;
+		}
+	} else if (dwidth == VME_D8) {
+		count32 = (count - done);
+		while (done < count32) {
+			*(u8 *)(buf + done) = fake_vmeread8(priv, addr + done,
+					aspace, cycle);
+			done += 1;
+		}
+
+	}
+
+	if ((dwidth == VME_D16) || (dwidth == VME_D32)) {
+		if ((count - done) & 0x2) {
+			*(u16 *)(buf + done) = fake_vmeread16(priv, addr + done,
+					aspace, cycle);
+			done += 2;
+		}
+	}
+	if ((count - done) & 0x1) {
+		*(u8 *)(buf + done) = fake_vmeread8(priv, addr + done, aspace,
+				cycle);
+		done += 1;
+	}
+
+out:
+	retval = count;
+
+	spin_unlock(&image->lock);
+
+	return retval;
+}
+
+void fake_vmewrite8(struct fake_driver *bridge, u8 *buf,
+		 unsigned long long addr, u32 aspace, u32 cycle)
+{
+	int i;
+	unsigned long long start, end, offset;
+	u8 *loc;
+
+	for (i = 0; i < FAKE_MAX_SLAVE; i++) {
+		if (aspace != bridge->slaves[i].aspace)
+			continue;
+
+		if (cycle != bridge->slaves[i].cycle)
+			continue;
+
+		start = bridge->slaves[i].vme_base;
+		end = bridge->slaves[i].vme_base + bridge->slaves[i].size;
+
+		if ((addr >= start) && (addr < end)) {
+			offset = addr - bridge->slaves[i].vme_base;
+			loc = (u8 *)((void *)bridge->slaves[i].buf_base + offset);
+			*loc = *buf;
+
+			break;
+		}
+	}
+
+	fake_lm_check(bridge, addr, aspace, cycle);
+
+}
+
+void fake_vmewrite16(struct fake_driver *bridge, u16 *buf,
+		unsigned long long addr, u32 aspace, u32 cycle)
+{
+	int i;
+	unsigned long long start, end, offset;
+	u16 *loc;
+
+	for (i = 0; i < FAKE_MAX_SLAVE; i++) {
+		if (aspace != bridge->slaves[i].aspace)
+			continue;
+
+		if (cycle != bridge->slaves[i].cycle)
+			continue;
+
+		start = bridge->slaves[i].vme_base;
+		end = bridge->slaves[i].vme_base + bridge->slaves[i].size;
+
+		if ((addr >= start) && ((addr + 1) < end)) {
+			offset = addr - bridge->slaves[i].vme_base;
+			loc = (u16 *)((void *)bridge->slaves[i].buf_base + offset);
+			*loc = *buf;
+
+			break;
+		}
+	}
+
+	fake_lm_check(bridge, addr, aspace, cycle);
+
+}
+
+void fake_vmewrite32(struct fake_driver *bridge, u32 *buf,
+		unsigned long long addr, u32 aspace, u32 cycle)
+{
+	int i;
+	unsigned long long start, end, offset;
+	u32 *loc;
+
+	for (i = 0; i < FAKE_MAX_SLAVE; i++) {
+		if (aspace != bridge->slaves[i].aspace)
+			continue;
+
+		if (cycle != bridge->slaves[i].cycle)
+			continue;
+
+		start = bridge->slaves[i].vme_base;
+		end = bridge->slaves[i].vme_base + bridge->slaves[i].size;
+
+		if ((addr >= start) && ((addr + 3) < end)) {
+			offset = addr - bridge->slaves[i].vme_base;
+			loc = (u32 *)((void *)bridge->slaves[i].buf_base + offset);
+			*loc = *buf;
+
+			break;
+		}
+	}
+
+	fake_lm_check(bridge, addr, aspace, cycle);
+
+}
+
+static ssize_t fake_master_write(struct vme_master_resource *image, void *buf,
+		size_t count, loff_t offset)
+{
+	int retval = 0;
+	u32 aspace, cycle, dwidth;
+	unsigned long long addr;
+	int i;
+	unsigned int done = 0;
+	unsigned int count32;
+
+	struct vme_bridge *fake_bridge;
+	struct fake_driver *bridge;
+
+	fake_bridge = image->parent;
+
+	bridge = fake_bridge->driver_priv;
+
+	i = image->number;
+
+	addr = bridge->masters[i].vme_base + offset;
+	aspace = bridge->masters[i].aspace;
+	cycle = bridge->masters[i].cycle;
+	dwidth = bridge->masters[i].dwidth;
+
+	spin_lock(&image->lock);
+
+	/* Here we apply for the same strategy we do in master_read
+	 * function in order to assure the correct cycles.
+	 */
+	if (addr & 0x1) {
+		fake_vmewrite8(bridge, (u8 *)buf, addr, aspace, cycle);
+		done += 1;
+		if (done == count)
+			goto out;
+	}
+
+	if ((dwidth == VME_D16) || (dwidth == VME_D32)) {
+		if ((addr + done) & 0x2) {
+			if ((count - done) < 2) {
+				fake_vmewrite8(bridge, (u8 *)(buf + done),
+						addr + done, aspace, cycle);
+				done += 1;
+				goto out;
+			} else {
+				fake_vmewrite16(bridge, (u16 *)(buf + done),
+						addr + done, aspace, cycle);
+				done += 2;
+			}
+		}
+	}
+
+	if (dwidth == VME_D32) {
+		count32 = (count - done) & ~0x3;
+		while (done < count32) {
+			fake_vmewrite32(bridge, (u32 *)(buf + done),
+					addr + done, aspace, cycle);
+			done += 4;
+		}
+	} else if (dwidth == VME_D16) {
+		count32 = (count - done) & ~0x3;
+		while (done < count32) {
+			fake_vmewrite16(bridge, (u16 *)(buf + done),
+					addr + done, aspace, cycle);
+			done += 2;
+		}
+	} else if (dwidth == VME_D8) {
+		count32 = (count - done);
+		while (done < count32) {
+			fake_vmewrite8(bridge, (u8 *)(buf + done), addr + done,
+					aspace, cycle);
+			done += 1;
+		}
+
+	}
+
+	if ((dwidth == VME_D16) || (dwidth == VME_D32)) {
+		if ((count - done) & 0x2) {
+			fake_vmewrite16(bridge, (u16 *)(buf + done),
+					addr + done, aspace, cycle);
+			done += 2;
+		}
+	}
+
+	if ((count - done) & 0x1) {
+		fake_vmewrite8(bridge, (u8 *)(buf + done), addr + done, aspace,
+				cycle);
+		done += 1;
+	}
+
+out:
+	retval = count;
+
+	spin_unlock(&image->lock);
+
+	return retval;
+}
+
+/*
+ * Perform an RMW cycle on the VME bus.
+ *
+ * Requires a previously configured master window, returns final value.
+ */
+static unsigned int fake_master_rmw(struct vme_master_resource *image,
+		unsigned int mask, unsigned int compare, unsigned int swap,
+		loff_t offset)
+{
+	u32 tmp, base;
+	u32 aspace, cycle;
+	int i;
+	struct fake_driver *bridge;
+
+	bridge = image->parent->driver_priv;
+
+	/* Find the PCI address that maps to the desired VME address */
+	i = image->number;
+
+	base = bridge->masters[i].vme_base;
+	aspace = bridge->masters[i].aspace;
+	cycle = bridge->masters[i].cycle;
+
+	/* Lock image */
+	spin_lock(&image->lock);
+
+	/* Read existing value */
+	tmp = fake_vmeread32(bridge, base + offset, aspace, cycle);
+
+	/* Perform check */
+	if ((tmp && mask) == (compare && mask)) {
+		tmp = tmp | (mask | swap);
+		tmp = tmp & (~mask | swap);
+
+		/* Write back */
+		fake_vmewrite32(bridge, &tmp, base + offset, aspace, cycle);
+	}
+
+	/* Unlock image */
+	spin_unlock(&image->lock);
+
+	return tmp;
+}
+
+/*
+ * All 4 location monitors reside at the same base - this is therefore a
+ * system wide configuration.
+ *
+ * This does not enable the LM monitor - that should be done when the first
+ * callback is attached and disabled when the last callback is removed.
+ */
+static int fake_lm_set(struct vme_lm_resource *lm, unsigned long long lm_base,
+		u32 aspace, u32 cycle)
+{
+	int i;
+	struct vme_bridge *fake_bridge;
+	struct fake_driver *bridge;
+
+	fake_bridge = lm->parent;
+
+	bridge = fake_bridge->driver_priv;
+
+	mutex_lock(&lm->mtx);
+
+	/* If we already have a callback attached, we can't move it! */
+	for (i = 0; i < lm->monitors; i++) {
+		if (bridge->lm_callback[i] != NULL) {
+			mutex_unlock(&lm->mtx);
+			pr_err("Location monitor callback attached, can't reset\n");
+			return -EBUSY;
+		}
+	}
+
+	switch (aspace) {
+	case VME_A16:
+	case VME_A24:
+	case VME_A32:
+	case VME_A64:
+		break;
+	default:
+		mutex_unlock(&lm->mtx);
+		pr_err("Invalid address space\n");
+		return -EINVAL;
+	}
+
+	bridge->lm_base = lm_base;
+	bridge->lm_aspace = aspace;
+	bridge->lm_cycle = cycle;
+
+	mutex_unlock(&lm->mtx);
+
+	return 0;
+}
+
+/* Get configuration of the callback monitor and return whether it is enabled
+ * or disabled.
+ */
+static int fake_lm_get(struct vme_lm_resource *lm,
+		unsigned long long *lm_base, u32 *aspace, u32 *cycle)
+{
+	struct fake_driver *bridge;
+
+	bridge = lm->parent->driver_priv;
+
+	mutex_lock(&lm->mtx);
+
+	*lm_base = bridge->lm_base;
+	*aspace = bridge->lm_aspace;
+	*cycle = bridge->lm_cycle;
+
+	mutex_unlock(&lm->mtx);
+
+	return bridge->lm_enabled;
+}
+
+/*
+ * Attach a callback to a specific location monitor.
+ *
+ * Callback will be passed the monitor triggered.
+ */
+static int fake_lm_attach(struct vme_lm_resource *lm, int monitor,
+		void (*callback)(void *), void *data)
+{
+	struct vme_bridge *fake_bridge;
+	struct fake_driver *bridge;
+
+	fake_bridge = lm->parent;
+
+	bridge = fake_bridge->driver_priv;
+
+	mutex_lock(&lm->mtx);
+
+	/* Ensure that the location monitor is configured - need PGM or DATA */
+	if (bridge->lm_cycle == 0) {
+		mutex_unlock(&lm->mtx);
+		pr_err("Location monitor not properly configured\n");
+		return -EINVAL;
+	}
+
+	/* Check that a callback isn't already attached */
+	if (bridge->lm_callback[monitor] != NULL) {
+		mutex_unlock(&lm->mtx);
+		pr_err("Existing callback attached\n");
+		return -EBUSY;
+	}
+
+	/* Attach callback */
+	bridge->lm_callback[monitor] = callback;
+	bridge->lm_data[monitor] = data;
+
+	/* Ensure that global Location Monitor Enable set */
+	bridge->lm_enabled = 1;
+
+	mutex_unlock(&lm->mtx);
+
+	return 0;
+}
+
+/*
+ * Detach a callback function forn a specific location monitor.
+ */
+static int fake_lm_detach(struct vme_lm_resource *lm, int monitor)
+{
+	u32 tmp;
+	int i;
+	struct fake_driver *bridge;
+
+	bridge = lm->parent->driver_priv;
+
+	mutex_lock(&lm->mtx);
+
+	/* Detach callback */
+	bridge->lm_callback[monitor] = NULL;
+	bridge->lm_data[monitor] = NULL;
+
+	/* If all location monitors disabled, disable global Location Monitor */
+	tmp = 0;
+	for (i = 0; i < lm->monitors; i++) {
+		if (bridge->lm_callback[i] != NULL)
+			tmp = 1;
+	}
+
+	if (tmp == 0)
+		bridge->lm_enabled = 0;
+
+	mutex_unlock(&lm->mtx);
+
+	return 0;
+}
+
+/*
+ * Determine Geographical Addressing
+ */
+static int fake_slot_get(struct vme_bridge *fake_bridge)
+{
+	return geoid;
+}
+
+static void *fake_alloc_consistent(struct device *parent, size_t size,
+		dma_addr_t *dma)
+{
+	void *alloc = kmalloc(size, GFP_KERNEL);
+
+	if (alloc != NULL)
+		*dma = (dma_addr_t)(unsigned long)alloc;
+
+	return alloc;
+}
+
+static void fake_free_consistent(struct device *parent, size_t size,
+		void *vaddr, dma_addr_t dma)
+{
+	kfree(vaddr);
+/*
+	dma_free_coherent(parent, size, vaddr, dma);
+*/
+}
+
+/*
+ * Configure CR/CSR space
+ *
+ * Access to the CR/CSR can be configured at power-up. The location of the
+ * CR/CSR registers in the CR/CSR address space is determined by the boards
+ * Geographic address.
+ *
+ * Each board has a 512kB window, with the highest 4kB being used for the
+ * boards registers, this means there is a fix length 508kB window which must
+ * be mapped onto PCI memory.
+ */
+static int fake_crcsr_init(struct vme_bridge *fake_bridge)
+{
+	u32 vstat;
+	struct fake_driver *bridge;
+
+	bridge = fake_bridge->driver_priv;
+
+	/* Allocate mem for CR/CSR image */
+	bridge->crcsr_kernel = kzalloc(VME_CRCSR_BUF_SIZE, GFP_KERNEL);
+	bridge->crcsr_bus = (dma_addr_t)bridge->crcsr_kernel;
+	if (bridge->crcsr_kernel == NULL)
+		return -ENOMEM;
+
+	vstat = fake_slot_get(fake_bridge);
+
+	pr_info("CR/CSR Offset: %d\n", vstat);
+
+	return 0;
+}
+
+static void fake_crcsr_exit(struct vme_bridge *fake_bridge)
+{
+	struct fake_driver *bridge;
+
+	bridge = fake_bridge->driver_priv;
+
+	kfree(bridge->crcsr_kernel);
+}
+
+
+static int __init fake_init(void)
+{
+	int retval, i;
+	struct list_head *pos = NULL, *n;
+	struct vme_bridge *fake_bridge;
+	struct fake_driver *fake_device;
+	struct vme_master_resource *master_image;
+	struct vme_slave_resource *slave_image;
+	struct vme_lm_resource *lm;
+
+	/* We need a fake parent device */
+	vme_root = __root_device_register("vme", THIS_MODULE);
+
+	/* If we want to support more than one bridge at some point, we need to
+	 * dynamically allocate this so we get one per device.
+	 */
+	fake_bridge = kzalloc(sizeof(struct vme_bridge), GFP_KERNEL);
+	if (fake_bridge == NULL) {
+		retval = -ENOMEM;
+		goto err_struct;
+	}
+
+	fake_device = kzalloc(sizeof(struct fake_driver), GFP_KERNEL);
+	if (fake_device == NULL) {
+		retval = -ENOMEM;
+		goto err_driver;
+	}
+
+	fake_bridge->driver_priv = fake_device;
+
+	fake_bridge->parent = vme_root;
+
+	fake_device->parent = fake_bridge;
+
+	/* Initialize wait queues & mutual exclusion flags */
+	mutex_init(&fake_device->vme_int);
+	mutex_init(&fake_bridge->irq_mtx);
+	tasklet_init(&fake_device->int_tasklet, fake_VIRQ_tasklet,
+			(unsigned long) fake_bridge);
+
+	strcpy(fake_bridge->name, driver_name);
+
+	/* Add master windows to list */
+	INIT_LIST_HEAD(&fake_bridge->master_resources);
+	for (i = 0; i < FAKE_MAX_MASTER; i++) {
+		master_image = kmalloc(sizeof(struct vme_master_resource),
+				GFP_KERNEL);
+		if (master_image == NULL) {
+			retval = -ENOMEM;
+			goto err_master;
+		}
+		master_image->parent = fake_bridge;
+		spin_lock_init(&master_image->lock);
+		master_image->locked = 0;
+		master_image->number = i;
+		master_image->address_attr = VME_A16 | VME_A24 | VME_A32 |
+			VME_A64;
+		master_image->cycle_attr = VME_SCT | VME_BLT | VME_MBLT |
+			VME_2eVME | VME_2eSST | VME_2eSSTB | VME_2eSST160 |
+			VME_2eSST267 | VME_2eSST320 | VME_SUPER | VME_USER |
+			VME_PROG | VME_DATA;
+		master_image->width_attr = VME_D16 | VME_D32;
+		memset(&master_image->bus_resource, 0,
+				sizeof(struct resource));
+		master_image->kern_base  = NULL;
+		list_add_tail(&master_image->list,
+				&fake_bridge->master_resources);
+	}
+
+	/* Add slave windows to list */
+	INIT_LIST_HEAD(&fake_bridge->slave_resources);
+	for (i = 0; i < FAKE_MAX_SLAVE; i++) {
+		slave_image = kmalloc(sizeof(struct vme_slave_resource),
+				GFP_KERNEL);
+		if (slave_image == NULL) {
+			retval = -ENOMEM;
+			goto err_slave;
+		}
+		slave_image->parent = fake_bridge;
+		mutex_init(&slave_image->mtx);
+		slave_image->locked = 0;
+		slave_image->number = i;
+		slave_image->address_attr = VME_A16 | VME_A24 | VME_A32 |
+			VME_A64 | VME_CRCSR | VME_USER1 | VME_USER2 |
+			VME_USER3 | VME_USER4;
+		slave_image->cycle_attr = VME_SCT | VME_BLT | VME_MBLT |
+			VME_2eVME | VME_2eSST | VME_2eSSTB | VME_2eSST160 |
+			VME_2eSST267 | VME_2eSST320 | VME_SUPER | VME_USER |
+			VME_PROG | VME_DATA;
+		list_add_tail(&slave_image->list,
+				&fake_bridge->slave_resources);
+	}
+
+	/* Add location monitor to list */
+	INIT_LIST_HEAD(&fake_bridge->lm_resources);
+	lm = kmalloc(sizeof(struct vme_lm_resource), GFP_KERNEL);
+	if (lm == NULL) {
+		pr_err("Failed to allocate memory for location monitor resource structure\n");
+		retval = -ENOMEM;
+		goto err_lm;
+	}
+	lm->parent = fake_bridge;
+	mutex_init(&lm->mtx);
+	lm->locked = 0;
+	lm->number = 1;
+	lm->monitors = 4;
+	list_add_tail(&lm->list, &fake_bridge->lm_resources);
+
+	fake_bridge->slave_get = fake_slave_get;
+	fake_bridge->slave_set = fake_slave_set;
+	fake_bridge->master_get = fake_master_get;
+	fake_bridge->master_set = fake_master_set;
+	fake_bridge->master_read = fake_master_read;
+	fake_bridge->master_write = fake_master_write;
+	fake_bridge->master_rmw = fake_master_rmw;
+	fake_bridge->irq_set = fake_irq_set;
+	fake_bridge->irq_generate = fake_irq_generate;
+	fake_bridge->lm_set = fake_lm_set;
+	fake_bridge->lm_get = fake_lm_get;
+	fake_bridge->lm_attach = fake_lm_attach;
+	fake_bridge->lm_detach = fake_lm_detach;
+	fake_bridge->slot_get = fake_slot_get;
+	fake_bridge->alloc_consistent = fake_alloc_consistent;
+	fake_bridge->free_consistent = fake_free_consistent;
+
+	pr_info("Board is%s the VME system controller\n",
+			(geoid == 1) ? "" : " not");
+
+	pr_info("VME geographical address is set to %d\n", geoid);
+
+	retval = fake_crcsr_init(fake_bridge);
+	if (retval) {
+		pr_err("CR/CSR configuration failed.\n");
+		goto err_crcsr;
+	}
+
+	retval = vme_register_bridge(fake_bridge);
+	if (retval != 0) {
+		pr_err("Chip Registration failed.\n");
+		goto err_reg;
+	}
+
+	exit_pointer = fake_bridge;
+
+	return 0;
+
+err_reg:
+	fake_crcsr_exit(fake_bridge);
+err_crcsr:
+err_lm:
+	/* resources are stored in link list */
+	list_for_each_safe(pos, n, &fake_bridge->lm_resources) {
+		lm = list_entry(pos, struct vme_lm_resource, list);
+		list_del(pos);
+		kfree(lm);
+	}
+err_slave:
+	/* resources are stored in link list */
+	list_for_each_safe(pos, n, &fake_bridge->slave_resources) {
+		slave_image = list_entry(pos, struct vme_slave_resource, list);
+		list_del(pos);
+		kfree(slave_image);
+	}
+err_master:
+	/* resources are stored in link list */
+	list_for_each_safe(pos, n, &fake_bridge->master_resources) {
+		master_image = list_entry(pos, struct vme_master_resource,
+				list);
+		list_del(pos);
+		kfree(master_image);
+	}
+
+	kfree(fake_device);
+err_driver:
+	kfree(fake_bridge);
+err_struct:
+	return retval;
+
+}
+
+
+static void __exit fake_exit(void)
+{
+	struct list_head *pos = NULL;
+	struct list_head *tmplist;
+	struct vme_master_resource *master_image;
+	struct vme_slave_resource *slave_image;
+	int i;
+	struct vme_bridge *fake_bridge;
+	struct fake_driver *bridge;
+
+	fake_bridge = exit_pointer;
+
+	bridge = fake_bridge->driver_priv;
+
+	pr_debug("Driver is being unloaded.\n");
+
+	/*
+	 *  Shutdown all inbound and outbound windows.
+	 */
+	for (i = 0; i < FAKE_MAX_MASTER; i++)
+		bridge->masters[i].enabled = 0;
+
+	for (i = 0; i < FAKE_MAX_SLAVE; i++)
+		bridge->slaves[i].enabled = 0;
+
+	/*
+	 *  Shutdown Location monitor.
+	 */
+	bridge->lm_enabled = 0;
+
+	vme_unregister_bridge(fake_bridge);
+
+	fake_crcsr_exit(fake_bridge);
+	/* resources are stored in link list */
+	list_for_each_safe(pos, tmplist, &fake_bridge->slave_resources) {
+		slave_image = list_entry(pos, struct vme_slave_resource, list);
+		list_del(pos);
+		kfree(slave_image);
+	}
+
+	/* resources are stored in link list */
+	list_for_each_safe(pos, tmplist, &fake_bridge->master_resources) {
+		master_image = list_entry(pos, struct vme_master_resource,
+				list);
+		list_del(pos);
+		kfree(master_image);
+	}
+
+	kfree(fake_bridge->driver_priv);
+
+	kfree(fake_bridge);
+
+	root_device_unregister(vme_root);
+}
+
+
+MODULE_PARM_DESC(geoid, "Set geographical addressing");
+module_param(geoid, int, 0);
+
+MODULE_DESCRIPTION("Fake VME bridge driver");
+MODULE_LICENSE("GPL");
+
+module_init(fake_init);
+module_exit(fake_exit);