[deliverable/linux.git] / drivers / virtio / virtio.c

#include <linux/virtio.h>
#include <linux/spinlock.h>
#include <linux/virtio_config.h>
#include <linux/module.h>
#include <linux/idr.h>

/* Unique numbering for virtio devices. */
static DEFINE_IDA(virtio_index_ida);

static ssize_t device_show(struct device *_d,
			   struct device_attribute *attr, char *buf)
{
	struct virtio_device *dev = dev_to_virtio(_d);
	return sprintf(buf, "0x%04x\n", dev->id.device);
}
static DEVICE_ATTR_RO(device);

static ssize_t vendor_show(struct device *_d,
			   struct device_attribute *attr, char *buf)
{
	struct virtio_device *dev = dev_to_virtio(_d);
	return sprintf(buf, "0x%04x\n", dev->id.vendor);
}
static DEVICE_ATTR_RO(vendor);

static ssize_t status_show(struct device *_d,
			   struct device_attribute *attr, char *buf)
{
	struct virtio_device *dev = dev_to_virtio(_d);
	return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
}
static DEVICE_ATTR_RO(status);

static ssize_t modalias_show(struct device *_d,
			     struct device_attribute *attr, char *buf)
{
	struct virtio_device *dev = dev_to_virtio(_d);
	return sprintf(buf, "virtio:d%08Xv%08X\n",
		       dev->id.device, dev->id.vendor);
}
static DEVICE_ATTR_RO(modalias);

static ssize_t features_show(struct device *_d,
			     struct device_attribute *attr, char *buf)
{
	struct virtio_device *dev = dev_to_virtio(_d);
	unsigned int i;
	ssize_t len = 0;

	/* We actually represent this as a bitstring, as it could be
	 * arbitrary length in future. */
	for (i = 0; i < sizeof(dev->features)*8; i++)
		len += sprintf(buf+len, "%c",
			       __virtio_test_bit(dev, i) ? '1' : '0');
	len += sprintf(buf+len, "\n");
	return len;
}
static DEVICE_ATTR_RO(features);

static struct attribute *virtio_dev_attrs[] = {
	&dev_attr_device.attr,
	&dev_attr_vendor.attr,
	&dev_attr_status.attr,
	&dev_attr_modalias.attr,
	&dev_attr_features.attr,
	NULL,
};
ATTRIBUTE_GROUPS(virtio_dev);

static inline int virtio_id_match(const struct virtio_device *dev,
				  const struct virtio_device_id *id)
{
	if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
		return 0;

	return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
}

/* This looks through all the IDs a driver claims to support.  If any of them
 * match, we return 1 and the kernel will call virtio_dev_probe(). */
static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
{
	unsigned int i;
	struct virtio_device *dev = dev_to_virtio(_dv);
	const struct virtio_device_id *ids;

	ids = drv_to_virtio(_dr)->id_table;
	for (i = 0; ids[i].device; i++)
		if (virtio_id_match(dev, &ids[i]))
			return 1;
	return 0;
}

static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
{
	struct virtio_device *dev = dev_to_virtio(_dv);

	return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
			      dev->id.device, dev->id.vendor);
}

static void add_status(struct virtio_device *dev, unsigned status)
{
	dev->config->set_status(dev, dev->config->get_status(dev) | status);
}

void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
					 unsigned int fbit)
{
	unsigned int i;
	struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);

	for (i = 0; i < drv->feature_table_size; i++)
		if (drv->feature_table[i] == fbit)
			return;

	if (drv->feature_table_legacy) {
		for (i = 0; i < drv->feature_table_size_legacy; i++)
			if (drv->feature_table_legacy[i] == fbit)
				return;
	}

	BUG();
}
EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);

static void __virtio_config_changed(struct virtio_device *dev)
{
	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);

	if (!dev->config_enabled)
		dev->config_change_pending = true;
	else if (drv && drv->config_changed)
		drv->config_changed(dev);
}

void virtio_config_changed(struct virtio_device *dev)
{
	unsigned long flags;

	spin_lock_irqsave(&dev->config_lock, flags);
	__virtio_config_changed(dev);
	spin_unlock_irqrestore(&dev->config_lock, flags);
}
EXPORT_SYMBOL_GPL(virtio_config_changed);

static void virtio_config_disable(struct virtio_device *dev)
{
	spin_lock_irq(&dev->config_lock);
	dev->config_enabled = false;
	spin_unlock_irq(&dev->config_lock);
}

static void virtio_config_enable(struct virtio_device *dev)
{
	spin_lock_irq(&dev->config_lock);
	dev->config_enabled = true;
	if (dev->config_change_pending)
		__virtio_config_changed(dev);
	dev->config_change_pending = false;
	spin_unlock_irq(&dev->config_lock);
}

static int virtio_dev_probe(struct device *_d)
{
	int err, i;
	struct virtio_device *dev = dev_to_virtio(_d);
	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
	u64 device_features;
	u64 driver_features;
	u64 driver_features_legacy;
	unsigned status;

	/* We have a driver! */
	add_status(dev, VIRTIO_CONFIG_S_DRIVER);

	/* Figure out what features the device supports. */
	device_features = dev->config->get_features(dev);

	/* Figure out what features the driver supports. */
	driver_features = 0;
	for (i = 0; i < drv->feature_table_size; i++) {
		unsigned int f = drv->feature_table[i];
		BUG_ON(f >= 64);
		driver_features |= (1ULL << f);
	}

	/* Some drivers have a separate feature table for virtio v1.0 */
	if (drv->feature_table_legacy) {
		driver_features_legacy = 0;
		for (i = 0; i < drv->feature_table_size_legacy; i++) {
			unsigned int f = drv->feature_table_legacy[i];
			BUG_ON(f >= 64);
			driver_features_legacy |= (1ULL << f);
		}
	} else {
		driver_features_legacy = driver_features;
	}

	/* Detect legacy-only drivers and disable VIRTIO_F_VERSION_1. */
	if (drv->legacy_only)
		device_features &= ~(1ULL << VIRTIO_F_VERSION_1);

	if (device_features & (1ULL << VIRTIO_F_VERSION_1))
		dev->features = driver_features & device_features;
	else
		dev->features = driver_features_legacy & device_features;

	/* Transport features always preserved to pass to finalize_features. */
	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
		if (device_features & (1ULL << i))
			__virtio_set_bit(dev, i);

	dev->config->finalize_features(dev);

	if (virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
		add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
		status = dev->config->get_status(dev);
		if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
			dev_err(_d, "virtio: device refuses features: %x\n",
			       status);
			err = -ENODEV;
			goto err;
		}
	}

	err = drv->probe(dev);
	if (err)
		goto err;

	add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
	if (drv->scan)
		drv->scan(dev);

	virtio_config_enable(dev);

	return 0;
err:
	add_status(dev, VIRTIO_CONFIG_S_FAILED);
	return err;

}

static int virtio_dev_remove(struct device *_d)
{
	struct virtio_device *dev = dev_to_virtio(_d);
	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);

	virtio_config_disable(dev);

	drv->remove(dev);

	/* Driver should have reset device. */
	WARN_ON_ONCE(dev->config->get_status(dev));

	/* Acknowledge the device's existence again. */
	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
	return 0;
}

static struct bus_type virtio_bus = {
	.name  = "virtio",
	.match = virtio_dev_match,
	.dev_groups = virtio_dev_groups,
	.uevent = virtio_uevent,
	.probe = virtio_dev_probe,
	.remove = virtio_dev_remove,
};

int register_virtio_driver(struct virtio_driver *driver)
{
	/* Catch this early. */
	BUG_ON(driver->feature_table_size && !driver->feature_table);
	driver->driver.bus = &virtio_bus;
	return driver_register(&driver->driver);
}
EXPORT_SYMBOL_GPL(register_virtio_driver);

void unregister_virtio_driver(struct virtio_driver *driver)
{
	driver_unregister(&driver->driver);
}
EXPORT_SYMBOL_GPL(unregister_virtio_driver);

int register_virtio_device(struct virtio_device *dev)
{
	int err;

	dev->dev.bus = &virtio_bus;

	/* Assign a unique device index and hence name. */
	err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
	if (err < 0)
		goto out;

	dev->index = err;
	dev_set_name(&dev->dev, "virtio%u", dev->index);

	spin_lock_init(&dev->config_lock);
	dev->config_enabled = false;
	dev->config_change_pending = false;

	/* We always start by resetting the device, in case a previous
	 * driver messed it up.  This also tests that code path a little. */
	dev->config->reset(dev);

	/* Acknowledge that we've seen the device. */
	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);

	INIT_LIST_HEAD(&dev->vqs);

	/* device_register() causes the bus infrastructure to look for a
	 * matching driver. */
	err = device_register(&dev->dev);
out:
	if (err)
		add_status(dev, VIRTIO_CONFIG_S_FAILED);
	return err;
}
EXPORT_SYMBOL_GPL(register_virtio_device);

void unregister_virtio_device(struct virtio_device *dev)
{
	int index = dev->index; /* save for after device release */

	device_unregister(&dev->dev);
	ida_simple_remove(&virtio_index_ida, index);
}
EXPORT_SYMBOL_GPL(unregister_virtio_device);

#ifdef CONFIG_PM_SLEEP
int virtio_device_freeze(struct virtio_device *dev)
{
	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);

	virtio_config_disable(dev);

	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;

	if (drv && drv->freeze)
		return drv->freeze(dev);

	return 0;
}
EXPORT_SYMBOL_GPL(virtio_device_freeze);

int virtio_device_restore(struct virtio_device *dev)
{
	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);

	/* We always start by resetting the device, in case a previous
	 * driver messed it up. */
	dev->config->reset(dev);

	/* Acknowledge that we've seen the device. */
	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);

	/* Maybe driver failed before freeze.
	 * Restore the failed status, for debugging. */
	if (dev->failed)
		add_status(dev, VIRTIO_CONFIG_S_FAILED);

	if (!drv)
		return 0;

	/* We have a driver! */
	add_status(dev, VIRTIO_CONFIG_S_DRIVER);

	dev->config->finalize_features(dev);

	if (drv->restore) {
		int ret = drv->restore(dev);
		if (ret) {
			add_status(dev, VIRTIO_CONFIG_S_FAILED);
			return ret;
		}
	}

	/* Finally, tell the device we're all set */
	add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);

	virtio_config_enable(dev);

	return 0;
}
EXPORT_SYMBOL_GPL(virtio_device_restore);
#endif

static int virtio_init(void)
{
	if (bus_register(&virtio_bus) != 0)
		panic("virtio bus registration failed");
	return 0;
}

static void __exit virtio_exit(void)
{
	bus_unregister(&virtio_bus);
}
core_initcall(virtio_init);
module_exit(virtio_exit);

MODULE_LICENSE("GPL");
Commit	Line	Data
	1	#include <linux/virtio.h>
	2	#include <linux/spinlock.h>
	3	#include <linux/virtio_config.h>
	4	#include <linux/module.h>
	5	#include <linux/idr.h>
	6
	7	/* Unique numbering for virtio devices. */
	8	static DEFINE_IDA(virtio_index_ida);
	9
	10	static ssize_t device_show(struct device *_d,
	11	struct device_attribute attr, char buf)
	12	{
	13	struct virtio_device *dev = dev_to_virtio(_d);
	14	return sprintf(buf, "0x%04x\n", dev->id.device);
	15	}
	16	static DEVICE_ATTR_RO(device);
	17
	18	static ssize_t vendor_show(struct device *_d,
	19	struct device_attribute attr, char buf)
	20	{
	21	struct virtio_device *dev = dev_to_virtio(_d);
	22	return sprintf(buf, "0x%04x\n", dev->id.vendor);
	23	}
	24	static DEVICE_ATTR_RO(vendor);
	25
	26	static ssize_t status_show(struct device *_d,
	27	struct device_attribute attr, char buf)
	28	{
	29	struct virtio_device *dev = dev_to_virtio(_d);
	30	return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
	31	}
	32	static DEVICE_ATTR_RO(status);
	33
	34	static ssize_t modalias_show(struct device *_d,
	35	struct device_attribute attr, char buf)
	36	{
	37	struct virtio_device *dev = dev_to_virtio(_d);
	38	return sprintf(buf, "virtio:d%08Xv%08X\n",
	39	dev->id.device, dev->id.vendor);
	40	}
	41	static DEVICE_ATTR_RO(modalias);
	42
	43	static ssize_t features_show(struct device *_d,
	44	struct device_attribute attr, char buf)
	45	{
	46	struct virtio_device *dev = dev_to_virtio(_d);
	47	unsigned int i;
	48	ssize_t len = 0;
	49
	50	/* We actually represent this as a bitstring, as it could be
	51	* arbitrary length in future. */
	52	for (i = 0; i < sizeof(dev->features)*8; i++)
	53	len += sprintf(buf+len, "%c",
	54	__virtio_test_bit(dev, i) ? '1' : '0');
	55	len += sprintf(buf+len, "\n");
	56	return len;
	57	}
	58	static DEVICE_ATTR_RO(features);
	59
	60	static struct attribute *virtio_dev_attrs[] = {
	61	&dev_attr_device.attr,
	62	&dev_attr_vendor.attr,
	63	&dev_attr_status.attr,
	64	&dev_attr_modalias.attr,
	65	&dev_attr_features.attr,
	66	NULL,
	67	};
	68	ATTRIBUTE_GROUPS(virtio_dev);
	69
	70	static inline int virtio_id_match(const struct virtio_device *dev,
	71	const struct virtio_device_id *id)
	72	{
	73	if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
	74	return 0;
	75
	76	return id->vendor == VIRTIO_DEV_ANY_ID \|\| id->vendor == dev->id.vendor;
	77	}
	78
	79	/* This looks through all the IDs a driver claims to support. If any of them
	80	* match, we return 1 and the kernel will call virtio_dev_probe(). */
	81	static int virtio_dev_match(struct device _dv, struct device_driver _dr)
	82	{
	83	unsigned int i;
	84	struct virtio_device *dev = dev_to_virtio(_dv);
	85	const struct virtio_device_id *ids;
	86
	87	ids = drv_to_virtio(_dr)->id_table;
	88	for (i = 0; ids[i].device; i++)
	89	if (virtio_id_match(dev, &ids[i]))
	90	return 1;
	91	return 0;
	92	}
	93
	94	static int virtio_uevent(struct device _dv, struct kobj_uevent_env env)
	95	{
	96	struct virtio_device *dev = dev_to_virtio(_dv);
	97
	98	return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
	99	dev->id.device, dev->id.vendor);
	100	}
	101
	102	static void add_status(struct virtio_device *dev, unsigned status)
	103	{
	104	dev->config->set_status(dev, dev->config->get_status(dev) \| status);
	105	}
	106
	107	void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
	108	unsigned int fbit)
	109	{
	110	unsigned int i;
	111	struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
	112
	113	for (i = 0; i < drv->feature_table_size; i++)
	114	if (drv->feature_table[i] == fbit)
	115	return;
	116
	117	if (drv->feature_table_legacy) {
	118	for (i = 0; i < drv->feature_table_size_legacy; i++)
	119	if (drv->feature_table_legacy[i] == fbit)
	120	return;
	121	}
	122
	123	BUG();
	124	}
	125	EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
	126
	127	static void __virtio_config_changed(struct virtio_device *dev)
	128	{
	129	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
	130
	131	if (!dev->config_enabled)
	132	dev->config_change_pending = true;
	133	else if (drv && drv->config_changed)
	134	drv->config_changed(dev);
	135	}
	136
	137	void virtio_config_changed(struct virtio_device *dev)
	138	{
	139	unsigned long flags;
	140
	141	spin_lock_irqsave(&dev->config_lock, flags);
	142	__virtio_config_changed(dev);
	143	spin_unlock_irqrestore(&dev->config_lock, flags);
	144	}
	145	EXPORT_SYMBOL_GPL(virtio_config_changed);
	146
	147	static void virtio_config_disable(struct virtio_device *dev)
	148	{
	149	spin_lock_irq(&dev->config_lock);
	150	dev->config_enabled = false;
	151	spin_unlock_irq(&dev->config_lock);
	152	}
	153
	154	static void virtio_config_enable(struct virtio_device *dev)
	155	{
	156	spin_lock_irq(&dev->config_lock);
	157	dev->config_enabled = true;
	158	if (dev->config_change_pending)
	159	__virtio_config_changed(dev);
	160	dev->config_change_pending = false;
	161	spin_unlock_irq(&dev->config_lock);
	162	}
	163
	164	static int virtio_dev_probe(struct device *_d)
	165	{
	166	int err, i;
	167	struct virtio_device *dev = dev_to_virtio(_d);
	168	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
	169	u64 device_features;
	170	u64 driver_features;
	171	u64 driver_features_legacy;
	172	unsigned status;
	173
	174	/* We have a driver! */
	175	add_status(dev, VIRTIO_CONFIG_S_DRIVER);
	176
	177	/* Figure out what features the device supports. */
	178	device_features = dev->config->get_features(dev);
	179
	180	/* Figure out what features the driver supports. */
	181	driver_features = 0;
	182	for (i = 0; i < drv->feature_table_size; i++) {
	183	unsigned int f = drv->feature_table[i];
	184	BUG_ON(f >= 64);
	185	driver_features \|= (1ULL << f);
	186	}
	187
	188	/* Some drivers have a separate feature table for virtio v1.0 */
	189	if (drv->feature_table_legacy) {
	190	driver_features_legacy = 0;
	191	for (i = 0; i < drv->feature_table_size_legacy; i++) {
	192	unsigned int f = drv->feature_table_legacy[i];
	193	BUG_ON(f >= 64);
	194	driver_features_legacy \|= (1ULL << f);
	195	}
	196	} else {
	197	driver_features_legacy = driver_features;
	198	}
	199
	200	/* Detect legacy-only drivers and disable VIRTIO_F_VERSION_1. */
	201	if (drv->legacy_only)
	202	device_features &= ~(1ULL << VIRTIO_F_VERSION_1);
	203
	204	if (device_features & (1ULL << VIRTIO_F_VERSION_1))
	205	dev->features = driver_features & device_features;
	206	else
	207	dev->features = driver_features_legacy & device_features;
	208
	209	/* Transport features always preserved to pass to finalize_features. */
	210	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
	211	if (device_features & (1ULL << i))
	212	__virtio_set_bit(dev, i);
	213
	214	dev->config->finalize_features(dev);
	215
	216	if (virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
	217	add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
	218	status = dev->config->get_status(dev);
	219	if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
	220	dev_err(_d, "virtio: device refuses features: %x\n",
	221	status);
	222	err = -ENODEV;
	223	goto err;
	224	}
	225	}
	226
	227	err = drv->probe(dev);
	228	if (err)
	229	goto err;
	230
	231	add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
	232	if (drv->scan)
	233	drv->scan(dev);
	234
	235	virtio_config_enable(dev);
	236
	237	return 0;
	238	err:
	239	add_status(dev, VIRTIO_CONFIG_S_FAILED);
	240	return err;
	241
	242	}
	243
	244	static int virtio_dev_remove(struct device *_d)
	245	{
	246	struct virtio_device *dev = dev_to_virtio(_d);
	247	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
	248
	249	virtio_config_disable(dev);
	250
	251	drv->remove(dev);
	252
	253	/* Driver should have reset device. */
	254	WARN_ON_ONCE(dev->config->get_status(dev));
	255
	256	/* Acknowledge the device's existence again. */
	257	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
	258	return 0;
	259	}
	260
	261	static struct bus_type virtio_bus = {
	262	.name = "virtio",
	263	.match = virtio_dev_match,
	264	.dev_groups = virtio_dev_groups,
	265	.uevent = virtio_uevent,
	266	.probe = virtio_dev_probe,
	267	.remove = virtio_dev_remove,
	268	};
	269
	270	int register_virtio_driver(struct virtio_driver *driver)
	271	{
	272	/* Catch this early. */
	273	BUG_ON(driver->feature_table_size && !driver->feature_table);
	274	driver->driver.bus = &virtio_bus;
	275	return driver_register(&driver->driver);
	276	}
	277	EXPORT_SYMBOL_GPL(register_virtio_driver);
	278
	279	void unregister_virtio_driver(struct virtio_driver *driver)
	280	{
	281	driver_unregister(&driver->driver);
	282	}
	283	EXPORT_SYMBOL_GPL(unregister_virtio_driver);
	284
	285	int register_virtio_device(struct virtio_device *dev)
	286	{
	287	int err;
	288
	289	dev->dev.bus = &virtio_bus;
	290
	291	/* Assign a unique device index and hence name. */
	292	err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
	293	if (err < 0)
	294	goto out;
	295
	296	dev->index = err;
	297	dev_set_name(&dev->dev, "virtio%u", dev->index);
	298
	299	spin_lock_init(&dev->config_lock);
	300	dev->config_enabled = false;
	301	dev->config_change_pending = false;
	302
	303	/* We always start by resetting the device, in case a previous
	304	* driver messed it up. This also tests that code path a little. */
	305	dev->config->reset(dev);
	306
	307	/* Acknowledge that we've seen the device. */
	308	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
	309
	310	INIT_LIST_HEAD(&dev->vqs);
	311
	312	/* device_register() causes the bus infrastructure to look for a
	313	* matching driver. */
	314	err = device_register(&dev->dev);
	315	out:
	316	if (err)
	317	add_status(dev, VIRTIO_CONFIG_S_FAILED);
	318	return err;
	319	}
	320	EXPORT_SYMBOL_GPL(register_virtio_device);
	321
	322	void unregister_virtio_device(struct virtio_device *dev)
	323	{
	324	int index = dev->index; /* save for after device release */
	325
	326	device_unregister(&dev->dev);
	327	ida_simple_remove(&virtio_index_ida, index);
	328	}
	329	EXPORT_SYMBOL_GPL(unregister_virtio_device);
	330
	331	#ifdef CONFIG_PM_SLEEP
	332	int virtio_device_freeze(struct virtio_device *dev)
	333	{
	334	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
	335
	336	virtio_config_disable(dev);
	337
	338	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
	339
	340	if (drv && drv->freeze)
	341	return drv->freeze(dev);
	342
	343	return 0;
	344	}
	345	EXPORT_SYMBOL_GPL(virtio_device_freeze);
	346
	347	int virtio_device_restore(struct virtio_device *dev)
	348	{
	349	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
	350
	351	/* We always start by resetting the device, in case a previous
	352	* driver messed it up. */
	353	dev->config->reset(dev);
	354
	355	/* Acknowledge that we've seen the device. */
	356	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
	357
	358	/* Maybe driver failed before freeze.
	359	* Restore the failed status, for debugging. */
	360	if (dev->failed)
	361	add_status(dev, VIRTIO_CONFIG_S_FAILED);
	362
	363	if (!drv)
	364	return 0;
	365
	366	/* We have a driver! */
	367	add_status(dev, VIRTIO_CONFIG_S_DRIVER);
	368
	369	dev->config->finalize_features(dev);
	370
	371	if (drv->restore) {
	372	int ret = drv->restore(dev);
	373	if (ret) {
	374	add_status(dev, VIRTIO_CONFIG_S_FAILED);
	375	return ret;
	376	}
	377	}
	378
	379	/* Finally, tell the device we're all set */
	380	add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
	381
	382	virtio_config_enable(dev);
	383
	384	return 0;
	385	}
	386	EXPORT_SYMBOL_GPL(virtio_device_restore);
	387	#endif
	388
	389	static int virtio_init(void)
	390	{
	391	if (bus_register(&virtio_bus) != 0)
	392	panic("virtio bus registration failed");
	393	return 0;
	394	}
	395
	396	static void __exit virtio_exit(void)
	397	{
	398	bus_unregister(&virtio_bus);
	399	}
	400	core_initcall(virtio_init);
	401	module_exit(virtio_exit);
	402
	403	MODULE_LICENSE("GPL");