Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1310 insertions, 0 deletions

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
new file mode 100644
index 000000000..74bab0628
--- /dev/null
+++ b/drivers/firewire/core-device.c
@@ -0,0 +1,1310 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Device probing and sysfs code.
+ *
+ * Copyright (C) 2005-2006  Kristian Hoegsberg <krh@bitplanet.net>
+ */
+
+#include <linux/bug.h>
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/firewire.h>
+#include <linux/firewire-constants.h>
+#include <linux/idr.h>
+#include <linux/jiffies.h>
+#include <linux/kobject.h>
+#include <linux/list.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/random.h>
+#include <linux/rwsem.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/workqueue.h>
+
+#include <linux/atomic.h>
+#include <asm/byteorder.h>
+
+#include "core.h"
+
+void fw_csr_iterator_init(struct fw_csr_iterator *ci, const u32 *p)
+{
+	ci->p = p + 1;
+	ci->end = ci->p + (p[0] >> 16);
+}
+EXPORT_SYMBOL(fw_csr_iterator_init);
+
+int fw_csr_iterator_next(struct fw_csr_iterator *ci, int *key, int *value)
+{
+	*key = *ci->p >> 24;
+	*value = *ci->p & 0xffffff;
+
+	return ci->p++ < ci->end;
+}
+EXPORT_SYMBOL(fw_csr_iterator_next);
+
+static const u32 *search_leaf(const u32 *directory, int search_key)
+{
+	struct fw_csr_iterator ci;
+	int last_key = 0, key, value;
+
+	fw_csr_iterator_init(&ci, directory);
+	while (fw_csr_iterator_next(&ci, &key, &value)) {
+		if (last_key == search_key &&
+		    key == (CSR_DESCRIPTOR | CSR_LEAF))
+			return ci.p - 1 + value;
+
+		last_key = key;
+	}
+
+	return NULL;
+}
+
+static int textual_leaf_to_string(const u32 *block, char *buf, size_t size)
+{
+	unsigned int quadlets, i;
+	char c;
+
+	if (!size || !buf)
+		return -EINVAL;
+
+	quadlets = min(block[0] >> 16, 256U);
+	if (quadlets < 2)
+		return -ENODATA;
+
+	if (block[1] != 0 || block[2] != 0)
+		/* unknown language/character set */
+		return -ENODATA;
+
+	block += 3;
+	quadlets -= 2;
+	for (i = 0; i < quadlets * 4 && i < size - 1; i++) {
+		c = block[i / 4] >> (24 - 8 * (i % 4));
+		if (c == '\0')
+			break;
+		buf[i] = c;
+	}
+	buf[i] = '\0';
+
+	return i;
+}
+
+/**
+ * fw_csr_string() - reads a string from the configuration ROM
+ * @directory:	e.g. root directory or unit directory
+ * @key:	the key of the preceding directory entry
+ * @buf:	where to put the string
+ * @size:	size of @buf, in bytes
+ *
+ * The string is taken from a minimal ASCII text descriptor leaf after
+ * the immediate entry with @key.  The string is zero-terminated.
+ * An overlong string is silently truncated such that it and the
+ * zero byte fit into @size.
+ *
+ * Returns strlen(buf) or a negative error code.
+ */
+int fw_csr_string(const u32 *directory, int key, char *buf, size_t size)
+{
+	const u32 *leaf = search_leaf(directory, key);
+	if (!leaf)
+		return -ENOENT;
+
+	return textual_leaf_to_string(leaf, buf, size);
+}
+EXPORT_SYMBOL(fw_csr_string);
+
+static void get_ids(const u32 *directory, int *id)
+{
+	struct fw_csr_iterator ci;
+	int key, value;
+
+	fw_csr_iterator_init(&ci, directory);
+	while (fw_csr_iterator_next(&ci, &key, &value)) {
+		switch (key) {
+		case CSR_VENDOR:	id[0] = value; break;
+		case CSR_MODEL:		id[1] = value; break;
+		case CSR_SPECIFIER_ID:	id[2] = value; break;
+		case CSR_VERSION:	id[3] = value; break;
+		}
+	}
+}
+
+static void get_modalias_ids(struct fw_unit *unit, int *id)
+{
+	get_ids(&fw_parent_device(unit)->config_rom[5], id);
+	get_ids(unit->directory, id);
+}
+
+static bool match_ids(const struct ieee1394_device_id *id_table, int *id)
+{
+	int match = 0;
+
+	if (id[0] == id_table->vendor_id)
+		match |= IEEE1394_MATCH_VENDOR_ID;
+	if (id[1] == id_table->model_id)
+		match |= IEEE1394_MATCH_MODEL_ID;
+	if (id[2] == id_table->specifier_id)
+		match |= IEEE1394_MATCH_SPECIFIER_ID;
+	if (id[3] == id_table->version)
+		match |= IEEE1394_MATCH_VERSION;
+
+	return (match & id_table->match_flags) == id_table->match_flags;
+}
+
+static const struct ieee1394_device_id *unit_match(struct device *dev,
+						   struct device_driver *drv)
+{
+	const struct ieee1394_device_id *id_table =
+			container_of(drv, struct fw_driver, driver)->id_table;
+	int id[] = {0, 0, 0, 0};
+
+	get_modalias_ids(fw_unit(dev), id);
+
+	for (; id_table->match_flags != 0; id_table++)
+		if (match_ids(id_table, id))
+			return id_table;
+
+	return NULL;
+}
+
+static bool is_fw_unit(struct device *dev);
+
+static int fw_unit_match(struct device *dev, struct device_driver *drv)
+{
+	/* We only allow binding to fw_units. */
+	return is_fw_unit(dev) && unit_match(dev, drv) != NULL;
+}
+
+static int fw_unit_probe(struct device *dev)
+{
+	struct fw_driver *driver =
+			container_of(dev->driver, struct fw_driver, driver);
+
+	return driver->probe(fw_unit(dev), unit_match(dev, dev->driver));
+}
+
+static void fw_unit_remove(struct device *dev)
+{
+	struct fw_driver *driver =
+			container_of(dev->driver, struct fw_driver, driver);
+
+	driver->remove(fw_unit(dev));
+}
+
+static int get_modalias(struct fw_unit *unit, char *buffer, size_t buffer_size)
+{
+	int id[] = {0, 0, 0, 0};
+
+	get_modalias_ids(unit, id);
+
+	return snprintf(buffer, buffer_size,
+			"ieee1394:ven%08Xmo%08Xsp%08Xver%08X",
+			id[0], id[1], id[2], id[3]);
+}
+
+static int fw_unit_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct fw_unit *unit = fw_unit(dev);
+	char modalias[64];
+
+	get_modalias(unit, modalias, sizeof(modalias));
+
+	if (add_uevent_var(env, "MODALIAS=%s", modalias))
+		return -ENOMEM;
+
+	return 0;
+}
+
+struct bus_type fw_bus_type = {
+	.name = "firewire",
+	.match = fw_unit_match,
+	.probe = fw_unit_probe,
+	.remove = fw_unit_remove,
+};
+EXPORT_SYMBOL(fw_bus_type);
+
+int fw_device_enable_phys_dma(struct fw_device *device)
+{
+	int generation = device->generation;
+
+	/* device->node_id, accessed below, must not be older than generation */
+	smp_rmb();
+
+	return device->card->driver->enable_phys_dma(device->card,
+						     device->node_id,
+						     generation);
+}
+EXPORT_SYMBOL(fw_device_enable_phys_dma);
+
+struct config_rom_attribute {
+	struct device_attribute attr;
+	u32 key;
+};
+
+static ssize_t show_immediate(struct device *dev,
+			      struct device_attribute *dattr, char *buf)
+{
+	struct config_rom_attribute *attr =
+		container_of(dattr, struct config_rom_attribute, attr);
+	struct fw_csr_iterator ci;
+	const u32 *dir;
+	int key, value, ret = -ENOENT;
+
+	down_read(&fw_device_rwsem);
+
+	if (is_fw_unit(dev))
+		dir = fw_unit(dev)->directory;
+	else
+		dir = fw_device(dev)->config_rom + 5;
+
+	fw_csr_iterator_init(&ci, dir);
+	while (fw_csr_iterator_next(&ci, &key, &value))
+		if (attr->key == key) {
+			ret = snprintf(buf, buf ? PAGE_SIZE : 0,
+				       "0x%06x\n", value);
+			break;
+		}
+
+	up_read(&fw_device_rwsem);
+
+	return ret;
+}
+
+#define IMMEDIATE_ATTR(name, key)				\
+	{ __ATTR(name, S_IRUGO, show_immediate, NULL), key }
+
+static ssize_t show_text_leaf(struct device *dev,
+			      struct device_attribute *dattr, char *buf)
+{
+	struct config_rom_attribute *attr =
+		container_of(dattr, struct config_rom_attribute, attr);
+	const u32 *dir;
+	size_t bufsize;
+	char dummy_buf[2];
+	int ret;
+
+	down_read(&fw_device_rwsem);
+
+	if (is_fw_unit(dev))
+		dir = fw_unit(dev)->directory;
+	else
+		dir = fw_device(dev)->config_rom + 5;
+
+	if (buf) {
+		bufsize = PAGE_SIZE - 1;
+	} else {
+		buf = dummy_buf;
+		bufsize = 1;
+	}
+
+	ret = fw_csr_string(dir, attr->key, buf, bufsize);
+
+	if (ret >= 0) {
+		/* Strip trailing whitespace and add newline. */
+		while (ret > 0 && isspace(buf[ret - 1]))
+			ret--;
+		strcpy(buf + ret, "\n");
+		ret++;
+	}
+
+	up_read(&fw_device_rwsem);
+
+	return ret;
+}
+
+#define TEXT_LEAF_ATTR(name, key)				\
+	{ __ATTR(name, S_IRUGO, show_text_leaf, NULL), key }
+
+static struct config_rom_attribute config_rom_attributes[] = {
+	IMMEDIATE_ATTR(vendor, CSR_VENDOR),
+	IMMEDIATE_ATTR(hardware_version, CSR_HARDWARE_VERSION),
+	IMMEDIATE_ATTR(specifier_id, CSR_SPECIFIER_ID),
+	IMMEDIATE_ATTR(version, CSR_VERSION),
+	IMMEDIATE_ATTR(model, CSR_MODEL),
+	TEXT_LEAF_ATTR(vendor_name, CSR_VENDOR),
+	TEXT_LEAF_ATTR(model_name, CSR_MODEL),
+	TEXT_LEAF_ATTR(hardware_version_name, CSR_HARDWARE_VERSION),
+};
+
+static void init_fw_attribute_group(struct device *dev,
+				    struct device_attribute *attrs,
+				    struct fw_attribute_group *group)
+{
+	struct device_attribute *attr;
+	int i, j;
+
+	for (j = 0; attrs[j].attr.name != NULL; j++)
+		group->attrs[j] = &attrs[j].attr;
+
+	for (i = 0; i < ARRAY_SIZE(config_rom_attributes); i++) {
+		attr = &config_rom_attributes[i].attr;
+		if (attr->show(dev, attr, NULL) < 0)
+			continue;
+		group->attrs[j++] = &attr->attr;
+	}
+
+	group->attrs[j] = NULL;
+	group->groups[0] = &group->group;
+	group->groups[1] = NULL;
+	group->group.attrs = group->attrs;
+	dev->groups = (const struct attribute_group **) group->groups;
+}
+
+static ssize_t modalias_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct fw_unit *unit = fw_unit(dev);
+	int length;
+
+	length = get_modalias(unit, buf, PAGE_SIZE);
+	strcpy(buf + length, "\n");
+
+	return length + 1;
+}
+
+static ssize_t rom_index_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct fw_device *device = fw_device(dev->parent);
+	struct fw_unit *unit = fw_unit(dev);
+
+	return sysfs_emit(buf, "%td\n", unit->directory - device->config_rom);
+}
+
+static struct device_attribute fw_unit_attributes[] = {
+	__ATTR_RO(modalias),
+	__ATTR_RO(rom_index),
+	__ATTR_NULL,
+};
+
+static ssize_t config_rom_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct fw_device *device = fw_device(dev);
+	size_t length;
+
+	down_read(&fw_device_rwsem);
+	length = device->config_rom_length * 4;
+	memcpy(buf, device->config_rom, length);
+	up_read(&fw_device_rwsem);
+
+	return length;
+}
+
+static ssize_t guid_show(struct device *dev,
+			 struct device_attribute *attr, char *buf)
+{
+	struct fw_device *device = fw_device(dev);
+	int ret;
+
+	down_read(&fw_device_rwsem);
+	ret = sysfs_emit(buf, "0x%08x%08x\n", device->config_rom[3], device->config_rom[4]);
+	up_read(&fw_device_rwsem);
+
+	return ret;
+}
+
+static ssize_t is_local_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct fw_device *device = fw_device(dev);
+
+	return sprintf(buf, "%u\n", device->is_local);
+}
+
+static int units_sprintf(char *buf, const u32 *directory)
+{
+	struct fw_csr_iterator ci;
+	int key, value;
+	int specifier_id = 0;
+	int version = 0;
+
+	fw_csr_iterator_init(&ci, directory);
+	while (fw_csr_iterator_next(&ci, &key, &value)) {
+		switch (key) {
+		case CSR_SPECIFIER_ID:
+			specifier_id = value;
+			break;
+		case CSR_VERSION:
+			version = value;
+			break;
+		}
+	}
+
+	return sprintf(buf, "0x%06x:0x%06x ", specifier_id, version);
+}
+
+static ssize_t units_show(struct device *dev,
+			  struct device_attribute *attr, char *buf)
+{
+	struct fw_device *device = fw_device(dev);
+	struct fw_csr_iterator ci;
+	int key, value, i = 0;
+
+	down_read(&fw_device_rwsem);
+	fw_csr_iterator_init(&ci, &device->config_rom[5]);
+	while (fw_csr_iterator_next(&ci, &key, &value)) {
+		if (key != (CSR_UNIT | CSR_DIRECTORY))
+			continue;
+		i += units_sprintf(&buf[i], ci.p + value - 1);
+		if (i >= PAGE_SIZE - (8 + 1 + 8 + 1))
+			break;
+	}
+	up_read(&fw_device_rwsem);
+
+	if (i)
+		buf[i - 1] = '\n';
+
+	return i;
+}
+
+static struct device_attribute fw_device_attributes[] = {
+	__ATTR_RO(config_rom),
+	__ATTR_RO(guid),
+	__ATTR_RO(is_local),
+	__ATTR_RO(units),
+	__ATTR_NULL,
+};
+
+static int read_rom(struct fw_device *device,
+		    int generation, int index, u32 *data)
+{
+	u64 offset = (CSR_REGISTER_BASE | CSR_CONFIG_ROM) + index * 4;
+	int i, rcode;
+
+	/* device->node_id, accessed below, must not be older than generation */
+	smp_rmb();
+
+	for (i = 10; i < 100; i += 10) {
+		rcode = fw_run_transaction(device->card,
+				TCODE_READ_QUADLET_REQUEST, device->node_id,
+				generation, device->max_speed, offset, data, 4);
+		if (rcode != RCODE_BUSY)
+			break;
+		msleep(i);
+	}
+	be32_to_cpus(data);
+
+	return rcode;
+}
+
+#define MAX_CONFIG_ROM_SIZE 256
+
+/*
+ * Read the bus info block, perform a speed probe, and read all of the rest of
+ * the config ROM.  We do all this with a cached bus generation.  If the bus
+ * generation changes under us, read_config_rom will fail and get retried.
+ * It's better to start all over in this case because the node from which we
+ * are reading the ROM may have changed the ROM during the reset.
+ * Returns either a result code or a negative error code.
+ */
+static int read_config_rom(struct fw_device *device, int generation)
+{
+	struct fw_card *card = device->card;
+	const u32 *old_rom, *new_rom;
+	u32 *rom, *stack;
+	u32 sp, key;
+	int i, end, length, ret;
+
+	rom = kmalloc(sizeof(*rom) * MAX_CONFIG_ROM_SIZE +
+		      sizeof(*stack) * MAX_CONFIG_ROM_SIZE, GFP_KERNEL);
+	if (rom == NULL)
+		return -ENOMEM;
+
+	stack = &rom[MAX_CONFIG_ROM_SIZE];
+	memset(rom, 0, sizeof(*rom) * MAX_CONFIG_ROM_SIZE);
+
+	device->max_speed = SCODE_100;
+
+	/* First read the bus info block. */
+	for (i = 0; i < 5; i++) {
+		ret = read_rom(device, generation, i, &rom[i]);
+		if (ret != RCODE_COMPLETE)
+			goto out;
+		/*
+		 * As per IEEE1212 7.2, during initialization, devices can
+		 * reply with a 0 for the first quadlet of the config
+		 * rom to indicate that they are booting (for example,
+		 * if the firmware is on the disk of a external
+		 * harddisk).  In that case we just fail, and the
+		 * retry mechanism will try again later.
+		 */
+		if (i == 0 && rom[i] == 0) {
+			ret = RCODE_BUSY;
+			goto out;
+		}
+	}
+
+	device->max_speed = device->node->max_speed;
+
+	/*
+	 * Determine the speed of
+	 *   - devices with link speed less than PHY speed,
+	 *   - devices with 1394b PHY (unless only connected to 1394a PHYs),
+	 *   - all devices if there are 1394b repeaters.
+	 * Note, we cannot use the bus info block's link_spd as starting point
+	 * because some buggy firmwares set it lower than necessary and because
+	 * 1394-1995 nodes do not have the field.
+	 */
+	if ((rom[2] & 0x7) < device->max_speed ||
+	    device->max_speed == SCODE_BETA ||
+	    card->beta_repeaters_present) {
+		u32 dummy;
+
+		/* for S1600 and S3200 */
+		if (device->max_speed == SCODE_BETA)
+			device->max_speed = card->link_speed;
+
+		while (device->max_speed > SCODE_100) {
+			if (read_rom(device, generation, 0, &dummy) ==
+			    RCODE_COMPLETE)
+				break;
+			device->max_speed--;
+		}
+	}
+
+	/*
+	 * Now parse the config rom.  The config rom is a recursive
+	 * directory structure so we parse it using a stack of
+	 * references to the blocks that make up the structure.  We
+	 * push a reference to the root directory on the stack to
+	 * start things off.
+	 */
+	length = i;
+	sp = 0;
+	stack[sp++] = 0xc0000005;
+	while (sp > 0) {
+		/*
+		 * Pop the next block reference of the stack.  The
+		 * lower 24 bits is the offset into the config rom,
+		 * the upper 8 bits are the type of the reference the
+		 * block.
+		 */
+		key = stack[--sp];
+		i = key & 0xffffff;
+		if (WARN_ON(i >= MAX_CONFIG_ROM_SIZE)) {
+			ret = -ENXIO;
+			goto out;
+		}
+
+		/* Read header quadlet for the block to get the length. */
+		ret = read_rom(device, generation, i, &rom[i]);
+		if (ret != RCODE_COMPLETE)
+			goto out;
+		end = i + (rom[i] >> 16) + 1;
+		if (end > MAX_CONFIG_ROM_SIZE) {
+			/*
+			 * This block extends outside the config ROM which is
+			 * a firmware bug.  Ignore this whole block, i.e.
+			 * simply set a fake block length of 0.
+			 */
+			fw_err(card, "skipped invalid ROM block %x at %llx\n",
+			       rom[i],
+			       i * 4 | CSR_REGISTER_BASE | CSR_CONFIG_ROM);
+			rom[i] = 0;
+			end = i;
+		}
+		i++;
+
+		/*
+		 * Now read in the block.  If this is a directory
+		 * block, check the entries as we read them to see if
+		 * it references another block, and push it in that case.
+		 */
+		for (; i < end; i++) {
+			ret = read_rom(device, generation, i, &rom[i]);
+			if (ret != RCODE_COMPLETE)
+				goto out;
+
+			if ((key >> 30) != 3 || (rom[i] >> 30) < 2)
+				continue;
+			/*
+			 * Offset points outside the ROM.  May be a firmware
+			 * bug or an Extended ROM entry (IEEE 1212-2001 clause
+			 * 7.7.18).  Simply overwrite this pointer here by a
+			 * fake immediate entry so that later iterators over
+			 * the ROM don't have to check offsets all the time.
+			 */
+			if (i + (rom[i] & 0xffffff) >= MAX_CONFIG_ROM_SIZE) {
+				fw_err(card,
+				       "skipped unsupported ROM entry %x at %llx\n",
+				       rom[i],
+				       i * 4 | CSR_REGISTER_BASE | CSR_CONFIG_ROM);
+				rom[i] = 0;
+				continue;
+			}
+			stack[sp++] = i + rom[i];
+		}
+		if (length < i)
+			length = i;
+	}
+
+	old_rom = device->config_rom;
+	new_rom = kmemdup(rom, length * 4, GFP_KERNEL);
+	if (new_rom == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	down_write(&fw_device_rwsem);
+	device->config_rom = new_rom;
+	device->config_rom_length = length;
+	up_write(&fw_device_rwsem);
+
+	kfree(old_rom);
+	ret = RCODE_COMPLETE;
+	device->max_rec	= rom[2] >> 12 & 0xf;
+	device->cmc	= rom[2] >> 30 & 1;
+	device->irmc	= rom[2] >> 31 & 1;
+ out:
+	kfree(rom);
+
+	return ret;
+}
+
+static void fw_unit_release(struct device *dev)
+{
+	struct fw_unit *unit = fw_unit(dev);
+
+	fw_device_put(fw_parent_device(unit));
+	kfree(unit);
+}
+
+static struct device_type fw_unit_type = {
+	.uevent		= fw_unit_uevent,
+	.release	= fw_unit_release,
+};
+
+static bool is_fw_unit(struct device *dev)
+{
+	return dev->type == &fw_unit_type;
+}
+
+static void create_units(struct fw_device *device)
+{
+	struct fw_csr_iterator ci;
+	struct fw_unit *unit;
+	int key, value, i;
+
+	i = 0;
+	fw_csr_iterator_init(&ci, &device->config_rom[5]);
+	while (fw_csr_iterator_next(&ci, &key, &value)) {
+		if (key != (CSR_UNIT | CSR_DIRECTORY))
+			continue;
+
+		/*
+		 * Get the address of the unit directory and try to
+		 * match the drivers id_tables against it.
+		 */
+		unit = kzalloc(sizeof(*unit), GFP_KERNEL);
+		if (unit == NULL)
+			continue;
+
+		unit->directory = ci.p + value - 1;
+		unit->device.bus = &fw_bus_type;
+		unit->device.type = &fw_unit_type;
+		unit->device.parent = &device->device;
+		dev_set_name(&unit->device, "%s.%d", dev_name(&device->device), i++);
+
+		BUILD_BUG_ON(ARRAY_SIZE(unit->attribute_group.attrs) <
+				ARRAY_SIZE(fw_unit_attributes) +
+				ARRAY_SIZE(config_rom_attributes));
+		init_fw_attribute_group(&unit->device,
+					fw_unit_attributes,
+					&unit->attribute_group);
+
+		fw_device_get(device);
+		if (device_register(&unit->device) < 0) {
+			put_device(&unit->device);
+			continue;
+		}
+	}
+}
+
+static int shutdown_unit(struct device *device, void *data)
+{
+	device_unregister(device);
+
+	return 0;
+}
+
+/*
+ * fw_device_rwsem acts as dual purpose mutex:
+ *   - serializes accesses to fw_device_idr,
+ *   - serializes accesses to fw_device.config_rom/.config_rom_length and
+ *     fw_unit.directory, unless those accesses happen at safe occasions
+ */
+DECLARE_RWSEM(fw_device_rwsem);
+
+DEFINE_IDR(fw_device_idr);
+int fw_cdev_major;
+
+struct fw_device *fw_device_get_by_devt(dev_t devt)
+{
+	struct fw_device *device;
+
+	down_read(&fw_device_rwsem);
+	device = idr_find(&fw_device_idr, MINOR(devt));
+	if (device)
+		fw_device_get(device);
+	up_read(&fw_device_rwsem);
+
+	return device;
+}
+
+struct workqueue_struct *fw_workqueue;
+EXPORT_SYMBOL(fw_workqueue);
+
+static void fw_schedule_device_work(struct fw_device *device,
+				    unsigned long delay)
+{
+	queue_delayed_work(fw_workqueue, &device->work, delay);
+}
+
+/*
+ * These defines control the retry behavior for reading the config
+ * rom.  It shouldn't be necessary to tweak these; if the device
+ * doesn't respond to a config rom read within 10 seconds, it's not
+ * going to respond at all.  As for the initial delay, a lot of
+ * devices will be able to respond within half a second after bus
+ * reset.  On the other hand, it's not really worth being more
+ * aggressive than that, since it scales pretty well; if 10 devices
+ * are plugged in, they're all getting read within one second.
+ */
+
+#define MAX_RETRIES	10
+#define RETRY_DELAY	(3 * HZ)
+#define INITIAL_DELAY	(HZ / 2)
+#define SHUTDOWN_DELAY	(2 * HZ)
+
+static void fw_device_shutdown(struct work_struct *work)
+{
+	struct fw_device *device =
+		container_of(work, struct fw_device, work.work);
+	int minor = MINOR(device->device.devt);
+
+	if (time_before64(get_jiffies_64(),
+			  device->card->reset_jiffies + SHUTDOWN_DELAY)
+	    && !list_empty(&device->card->link)) {
+		fw_schedule_device_work(device, SHUTDOWN_DELAY);
+		return;
+	}
+
+	if (atomic_cmpxchg(&device->state,
+			   FW_DEVICE_GONE,
+			   FW_DEVICE_SHUTDOWN) != FW_DEVICE_GONE)
+		return;
+
+	fw_device_cdev_remove(device);
+	device_for_each_child(&device->device, NULL, shutdown_unit);
+	device_unregister(&device->device);
+
+	down_write(&fw_device_rwsem);
+	idr_remove(&fw_device_idr, minor);
+	up_write(&fw_device_rwsem);
+
+	fw_device_put(device);
+}
+
+static void fw_device_release(struct device *dev)
+{
+	struct fw_device *device = fw_device(dev);
+	struct fw_card *card = device->card;
+	unsigned long flags;
+
+	/*
+	 * Take the card lock so we don't set this to NULL while a
+	 * FW_NODE_UPDATED callback is being handled or while the
+	 * bus manager work looks at this node.
+	 */
+	spin_lock_irqsave(&card->lock, flags);
+	device->node->data = NULL;
+	spin_unlock_irqrestore(&card->lock, flags);
+
+	fw_node_put(device->node);
+	kfree(device->config_rom);
+	kfree(device);
+	fw_card_put(card);
+}
+
+static struct device_type fw_device_type = {
+	.release = fw_device_release,
+};
+
+static bool is_fw_device(struct device *dev)
+{
+	return dev->type == &fw_device_type;
+}
+
+static int update_unit(struct device *dev, void *data)
+{
+	struct fw_unit *unit = fw_unit(dev);
+	struct fw_driver *driver = (struct fw_driver *)dev->driver;
+
+	if (is_fw_unit(dev) && driver != NULL && driver->update != NULL) {
+		device_lock(dev);
+		driver->update(unit);
+		device_unlock(dev);
+	}
+
+	return 0;
+}
+
+static void fw_device_update(struct work_struct *work)
+{
+	struct fw_device *device =
+		container_of(work, struct fw_device, work.work);
+
+	fw_device_cdev_update(device);
+	device_for_each_child(&device->device, NULL, update_unit);
+}
+
+/*
+ * If a device was pending for deletion because its node went away but its
+ * bus info block and root directory header matches that of a newly discovered
+ * device, revive the existing fw_device.
+ * The newly allocated fw_device becomes obsolete instead.
+ */
+static int lookup_existing_device(struct device *dev, void *data)
+{
+	struct fw_device *old = fw_device(dev);
+	struct fw_device *new = data;
+	struct fw_card *card = new->card;
+	int match = 0;
+
+	if (!is_fw_device(dev))
+		return 0;
+
+	down_read(&fw_device_rwsem); /* serialize config_rom access */
+	spin_lock_irq(&card->lock);  /* serialize node access */
+
+	if (memcmp(old->config_rom, new->config_rom, 6 * 4) == 0 &&
+	    atomic_cmpxchg(&old->state,
+			   FW_DEVICE_GONE,
+			   FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
+		struct fw_node *current_node = new->node;
+		struct fw_node *obsolete_node = old->node;
+
+		new->node = obsolete_node;
+		new->node->data = new;
+		old->node = current_node;
+		old->node->data = old;
+
+		old->max_speed = new->max_speed;
+		old->node_id = current_node->node_id;
+		smp_wmb();  /* update node_id before generation */
+		old->generation = card->generation;
+		old->config_rom_retries = 0;
+		fw_notice(card, "rediscovered device %s\n", dev_name(dev));
+
+		old->workfn = fw_device_update;
+		fw_schedule_device_work(old, 0);
+
+		if (current_node == card->root_node)
+			fw_schedule_bm_work(card, 0);
+
+		match = 1;
+	}
+
+	spin_unlock_irq(&card->lock);
+	up_read(&fw_device_rwsem);
+
+	return match;
+}
+
+enum { BC_UNKNOWN = 0, BC_UNIMPLEMENTED, BC_IMPLEMENTED, };
+
+static void set_broadcast_channel(struct fw_device *device, int generation)
+{
+	struct fw_card *card = device->card;
+	__be32 data;
+	int rcode;
+
+	if (!card->broadcast_channel_allocated)
+		return;
+
+	/*
+	 * The Broadcast_Channel Valid bit is required by nodes which want to
+	 * transmit on this channel.  Such transmissions are practically
+	 * exclusive to IP over 1394 (RFC 2734).  IP capable nodes are required
+	 * to be IRM capable and have a max_rec of 8 or more.  We use this fact
+	 * to narrow down to which nodes we send Broadcast_Channel updates.
+	 */
+	if (!device->irmc || device->max_rec < 8)
+		return;
+
+	/*
+	 * Some 1394-1995 nodes crash if this 1394a-2000 register is written.
+	 * Perform a read test first.
+	 */
+	if (device->bc_implemented == BC_UNKNOWN) {
+		rcode = fw_run_transaction(card, TCODE_READ_QUADLET_REQUEST,
+				device->node_id, generation, device->max_speed,
+				CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
+				&data, 4);
+		switch (rcode) {
+		case RCODE_COMPLETE:
+			if (data & cpu_to_be32(1 << 31)) {
+				device->bc_implemented = BC_IMPLEMENTED;
+				break;
+			}
+			fallthrough;	/* to case address error */
+		case RCODE_ADDRESS_ERROR:
+			device->bc_implemented = BC_UNIMPLEMENTED;
+		}
+	}
+
+	if (device->bc_implemented == BC_IMPLEMENTED) {
+		data = cpu_to_be32(BROADCAST_CHANNEL_INITIAL |
+				   BROADCAST_CHANNEL_VALID);
+		fw_run_transaction(card, TCODE_WRITE_QUADLET_REQUEST,
+				device->node_id, generation, device->max_speed,
+				CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
+				&data, 4);
+	}
+}
+
+int fw_device_set_broadcast_channel(struct device *dev, void *gen)
+{
+	if (is_fw_device(dev))
+		set_broadcast_channel(fw_device(dev), (long)gen);
+
+	return 0;
+}
+
+static void fw_device_init(struct work_struct *work)
+{
+	struct fw_device *device =
+		container_of(work, struct fw_device, work.work);
+	struct fw_card *card = device->card;
+	struct device *revived_dev;
+	int minor, ret;
+
+	/*
+	 * All failure paths here set node->data to NULL, so that we
+	 * don't try to do device_for_each_child() on a kfree()'d
+	 * device.
+	 */
+
+	ret = read_config_rom(device, device->generation);
+	if (ret != RCODE_COMPLETE) {
+		if (device->config_rom_retries < MAX_RETRIES &&
+		    atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
+			device->config_rom_retries++;
+			fw_schedule_device_work(device, RETRY_DELAY);
+		} else {
+			if (device->node->link_on)
+				fw_notice(card, "giving up on node %x: reading config rom failed: %s\n",
+					  device->node_id,
+					  fw_rcode_string(ret));
+			if (device->node == card->root_node)
+				fw_schedule_bm_work(card, 0);
+			fw_device_release(&device->device);
+		}
+		return;
+	}
+
+	revived_dev = device_find_child(card->device,
+					device, lookup_existing_device);
+	if (revived_dev) {
+		put_device(revived_dev);
+		fw_device_release(&device->device);
+
+		return;
+	}
+
+	device_initialize(&device->device);
+
+	fw_device_get(device);
+	down_write(&fw_device_rwsem);
+	minor = idr_alloc(&fw_device_idr, device, 0, 1 << MINORBITS,
+			GFP_KERNEL);
+	up_write(&fw_device_rwsem);
+
+	if (minor < 0)
+		goto error;
+
+	device->device.bus = &fw_bus_type;
+	device->device.type = &fw_device_type;
+	device->device.parent = card->device;
+	device->device.devt = MKDEV(fw_cdev_major, minor);
+	dev_set_name(&device->device, "fw%d", minor);
+
+	BUILD_BUG_ON(ARRAY_SIZE(device->attribute_group.attrs) <
+			ARRAY_SIZE(fw_device_attributes) +
+			ARRAY_SIZE(config_rom_attributes));
+	init_fw_attribute_group(&device->device,
+				fw_device_attributes,
+				&device->attribute_group);
+
+	if (device_add(&device->device)) {
+		fw_err(card, "failed to add device\n");
+		goto error_with_cdev;
+	}
+
+	create_units(device);
+
+	/*
+	 * Transition the device to running state.  If it got pulled
+	 * out from under us while we did the initialization work, we
+	 * have to shut down the device again here.  Normally, though,
+	 * fw_node_event will be responsible for shutting it down when
+	 * necessary.  We have to use the atomic cmpxchg here to avoid
+	 * racing with the FW_NODE_DESTROYED case in
+	 * fw_node_event().
+	 */
+	if (atomic_cmpxchg(&device->state,
+			   FW_DEVICE_INITIALIZING,
+			   FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
+		device->workfn = fw_device_shutdown;
+		fw_schedule_device_work(device, SHUTDOWN_DELAY);
+	} else {
+		fw_notice(card, "created device %s: GUID %08x%08x, S%d00\n",
+			  dev_name(&device->device),
+			  device->config_rom[3], device->config_rom[4],
+			  1 << device->max_speed);
+		device->config_rom_retries = 0;
+
+		set_broadcast_channel(device, device->generation);
+
+		add_device_randomness(&device->config_rom[3], 8);
+	}
+
+	/*
+	 * Reschedule the IRM work if we just finished reading the
+	 * root node config rom.  If this races with a bus reset we
+	 * just end up running the IRM work a couple of extra times -
+	 * pretty harmless.
+	 */
+	if (device->node == card->root_node)
+		fw_schedule_bm_work(card, 0);
+
+	return;
+
+ error_with_cdev:
+	down_write(&fw_device_rwsem);
+	idr_remove(&fw_device_idr, minor);
+	up_write(&fw_device_rwsem);
+ error:
+	fw_device_put(device);		/* fw_device_idr's reference */
+
+	put_device(&device->device);	/* our reference */
+}
+
+/* Reread and compare bus info block and header of root directory */
+static int reread_config_rom(struct fw_device *device, int generation,
+			     bool *changed)
+{
+	u32 q;
+	int i, rcode;
+
+	for (i = 0; i < 6; i++) {
+		rcode = read_rom(device, generation, i, &q);
+		if (rcode != RCODE_COMPLETE)
+			return rcode;
+
+		if (i == 0 && q == 0)
+			/* inaccessible (see read_config_rom); retry later */
+			return RCODE_BUSY;
+
+		if (q != device->config_rom[i]) {
+			*changed = true;
+			return RCODE_COMPLETE;
+		}
+	}
+
+	*changed = false;
+	return RCODE_COMPLETE;
+}
+
+static void fw_device_refresh(struct work_struct *work)
+{
+	struct fw_device *device =
+		container_of(work, struct fw_device, work.work);
+	struct fw_card *card = device->card;
+	int ret, node_id = device->node_id;
+	bool changed;
+
+	ret = reread_config_rom(device, device->generation, &changed);
+	if (ret != RCODE_COMPLETE)
+		goto failed_config_rom;
+
+	if (!changed) {
+		if (atomic_cmpxchg(&device->state,
+				   FW_DEVICE_INITIALIZING,
+				   FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
+			goto gone;
+
+		fw_device_update(work);
+		device->config_rom_retries = 0;
+		goto out;
+	}
+
+	/*
+	 * Something changed.  We keep things simple and don't investigate
+	 * further.  We just destroy all previous units and create new ones.
+	 */
+	device_for_each_child(&device->device, NULL, shutdown_unit);
+
+	ret = read_config_rom(device, device->generation);
+	if (ret != RCODE_COMPLETE)
+		goto failed_config_rom;
+
+	fw_device_cdev_update(device);
+	create_units(device);
+
+	/* Userspace may want to re-read attributes. */
+	kobject_uevent(&device->device.kobj, KOBJ_CHANGE);
+
+	if (atomic_cmpxchg(&device->state,
+			   FW_DEVICE_INITIALIZING,
+			   FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
+		goto gone;
+
+	fw_notice(card, "refreshed device %s\n", dev_name(&device->device));
+	device->config_rom_retries = 0;
+	goto out;
+
+ failed_config_rom:
+	if (device->config_rom_retries < MAX_RETRIES &&
+	    atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
+		device->config_rom_retries++;
+		fw_schedule_device_work(device, RETRY_DELAY);
+		return;
+	}
+
+	fw_notice(card, "giving up on refresh of device %s: %s\n",
+		  dev_name(&device->device), fw_rcode_string(ret));
+ gone:
+	atomic_set(&device->state, FW_DEVICE_GONE);
+	device->workfn = fw_device_shutdown;
+	fw_schedule_device_work(device, SHUTDOWN_DELAY);
+ out:
+	if (node_id == card->root_node->node_id)
+		fw_schedule_bm_work(card, 0);
+}
+
+static void fw_device_workfn(struct work_struct *work)
+{
+	struct fw_device *device = container_of(to_delayed_work(work),
+						struct fw_device, work);
+	device->workfn(work);
+}
+
+void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
+{
+	struct fw_device *device;
+
+	switch (event) {
+	case FW_NODE_CREATED:
+		/*
+		 * Attempt to scan the node, regardless whether its self ID has
+		 * the L (link active) flag set or not.  Some broken devices
+		 * send L=0 but have an up-and-running link; others send L=1
+		 * without actually having a link.
+		 */
+ create:
+		device = kzalloc(sizeof(*device), GFP_ATOMIC);
+		if (device == NULL)
+			break;
+
+		/*
+		 * Do minimal initialization of the device here, the
+		 * rest will happen in fw_device_init().
+		 *
+		 * Attention:  A lot of things, even fw_device_get(),
+		 * cannot be done before fw_device_init() finished!
+		 * You can basically just check device->state and
+		 * schedule work until then, but only while holding
+		 * card->lock.
+		 */
+		atomic_set(&device->state, FW_DEVICE_INITIALIZING);
+		device->card = fw_card_get(card);
+		device->node = fw_node_get(node);
+		device->node_id = node->node_id;
+		device->generation = card->generation;
+		device->is_local = node == card->local_node;
+		mutex_init(&device->client_list_mutex);
+		INIT_LIST_HEAD(&device->client_list);
+
+		/*
+		 * Set the node data to point back to this device so
+		 * FW_NODE_UPDATED callbacks can update the node_id
+		 * and generation for the device.
+		 */
+		node->data = device;
+
+		/*
+		 * Many devices are slow to respond after bus resets,
+		 * especially if they are bus powered and go through
+		 * power-up after getting plugged in.  We schedule the
+		 * first config rom scan half a second after bus reset.
+		 */
+		device->workfn = fw_device_init;
+		INIT_DELAYED_WORK(&device->work, fw_device_workfn);
+		fw_schedule_device_work(device, INITIAL_DELAY);
+		break;
+
+	case FW_NODE_INITIATED_RESET:
+	case FW_NODE_LINK_ON:
+		device = node->data;
+		if (device == NULL)
+			goto create;
+
+		device->node_id = node->node_id;
+		smp_wmb();  /* update node_id before generation */
+		device->generation = card->generation;
+		if (atomic_cmpxchg(&device->state,
+			    FW_DEVICE_RUNNING,
+			    FW_DEVICE_INITIALIZING) == FW_DEVICE_RUNNING) {
+			device->workfn = fw_device_refresh;
+			fw_schedule_device_work(device,
+				device->is_local ? 0 : INITIAL_DELAY);
+		}
+		break;
+
+	case FW_NODE_UPDATED:
+		device = node->data;
+		if (device == NULL)
+			break;
+
+		device->node_id = node->node_id;
+		smp_wmb();  /* update node_id before generation */
+		device->generation = card->generation;
+		if (atomic_read(&device->state) == FW_DEVICE_RUNNING) {
+			device->workfn = fw_device_update;
+			fw_schedule_device_work(device, 0);
+		}
+		break;
+
+	case FW_NODE_DESTROYED:
+	case FW_NODE_LINK_OFF:
+		if (!node->data)
+			break;
+
+		/*
+		 * Destroy the device associated with the node.  There
+		 * are two cases here: either the device is fully
+		 * initialized (FW_DEVICE_RUNNING) or we're in the
+		 * process of reading its config rom
+		 * (FW_DEVICE_INITIALIZING).  If it is fully
+		 * initialized we can reuse device->work to schedule a
+		 * full fw_device_shutdown().  If not, there's work
+		 * scheduled to read it's config rom, and we just put
+		 * the device in shutdown state to have that code fail
+		 * to create the device.
+		 */
+		device = node->data;
+		if (atomic_xchg(&device->state,
+				FW_DEVICE_GONE) == FW_DEVICE_RUNNING) {
+			device->workfn = fw_device_shutdown;
+			fw_schedule_device_work(device,
+				list_empty(&card->link) ? 0 : SHUTDOWN_DELAY);
+		}
+		break;
+	}
+}