[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 < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++)
		len += sprintf(buf+len, "%c",
			       test_bit(i, dev->features) ? '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;
	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);
	u32 device_features;

	/* 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);

	/* Features supported by both device and driver into dev->features. */
	memset(dev->features, 0, sizeof(dev->features));
	for (i = 0; i < drv->feature_table_size; i++) {
		unsigned int f = drv->feature_table[i];
		BUG_ON(f >= 32);
		if (device_features & (1 << f))
			set_bit(f, dev->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 & (1 << i))
			set_bit(i, dev->features);

	dev->config->finalize_features(dev);

	err = drv->probe(dev);
	if (err)
		add_status(dev, VIRTIO_CONFIG_S_FAILED);
	else {
		add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
		if (drv->scan)
			drv->scan(dev);

		virtio_config_enable(dev);
	}

	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
ec3d41c4 RR	1	#include <linux/virtio.h>
	2	#include <linux/spinlock.h>
	3	#include <linux/virtio_config.h>
b5a2c4f1	4	#include <linux/module.h>
90e03207	5	#include <linux/idr.h>
ec3d41c4	6
b769f579	7	/* Unique numbering for virtio devices. */
90e03207	8	static DEFINE_IDA(virtio_index_ida);
b769f579	9
ec3d41c4 RR	10	static ssize_t device_show(struct device *_d,
	11	struct device_attribute attr, char buf)
	12	{
9bffdca8	13	struct virtio_device *dev = dev_to_virtio(_d);
be6528b2	14	return sprintf(buf, "0x%04x\n", dev->id.device);
ec3d41c4	15	}
3736dab6 GKH	16	static DEVICE_ATTR_RO(device);
3736dab6 GKH	17
ec3d41c4 RR	18	static ssize_t vendor_show(struct device *_d,
	19	struct device_attribute attr, char buf)
	20	{
9bffdca8	21	struct virtio_device *dev = dev_to_virtio(_d);
be6528b2	22	return sprintf(buf, "0x%04x\n", dev->id.vendor);
ec3d41c4	23	}
3736dab6 GKH	24	static DEVICE_ATTR_RO(vendor);
3736dab6 GKH	25
ec3d41c4 RR	26	static ssize_t status_show(struct device *_d,
	27	struct device_attribute attr, char buf)
	28	{
9bffdca8	29	struct virtio_device *dev = dev_to_virtio(_d);
be6528b2	30	return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
ec3d41c4	31	}
3736dab6 GKH	32	static DEVICE_ATTR_RO(status);
3736dab6 GKH	33
b01d9f28 RR	34	static ssize_t modalias_show(struct device *_d,
	35	struct device_attribute attr, char buf)
	36	{
9bffdca8	37	struct virtio_device *dev = dev_to_virtio(_d);
b01d9f28 RR	38	return sprintf(buf, "virtio:d%08Xv%08X\n",
	39	dev->id.device, dev->id.vendor);
	40	}
3736dab6 GKH	41	static DEVICE_ATTR_RO(modalias);
3736dab6 GKH	42
a9289282 RR	43	static ssize_t features_show(struct device *_d,
	44	struct device_attribute attr, char buf)
	45	{
9bffdca8	46	struct virtio_device *dev = dev_to_virtio(_d);
a9289282 RR	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 < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++)
	53	len += sprintf(buf+len, "%c",
	54	test_bit(i, dev->features) ? '1' : '0');
	55	len += sprintf(buf+len, "\n");
	56	return len;
	57	}
3736dab6 GKH	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,
ec3d41c4	67	};
3736dab6	68	ATTRIBUTE_GROUPS(virtio_dev);
ec3d41c4 RR	69
	70	static inline int virtio_id_match(const struct virtio_device *dev,
	71	const struct virtio_device_id *id)
	72	{
e3353853	73	if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
ec3d41c4 RR	74	return 0;
ec3d41c4 RR	75
c89e8016	76	return id->vendor == VIRTIO_DEV_ANY_ID \|\| id->vendor == dev->id.vendor;
ec3d41c4 RR	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;
9bffdca8	84	struct virtio_device *dev = dev_to_virtio(_dv);
ec3d41c4 RR	85	const struct virtio_device_id *ids;
ec3d41c4 RR	86
9a2bdcc8	87	ids = drv_to_virtio(_dr)->id_table;
ec3d41c4 RR	88	for (i = 0; ids[i].device; i++)
	89	if (virtio_id_match(dev, &ids[i]))
	90	return 1;
	91	return 0;
	92	}
	93
b01d9f28 RR	94	static int virtio_uevent(struct device _dv, struct kobj_uevent_env env)
b01d9f28 RR	95	{
9bffdca8	96	struct virtio_device *dev = dev_to_virtio(_dv);
b01d9f28 RR	97
	98	return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
	99	dev->id.device, dev->id.vendor);
	100	}
	101
ec3d41c4 RR	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
c45a6816 RR	107	void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
	108	unsigned int fbit)
	109	{
	110	unsigned int i;
9a2bdcc8	111	struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
c45a6816 RR	112
	113	for (i = 0; i < drv->feature_table_size; i++)
	114	if (drv->feature_table[i] == fbit)
	115	return;
	116	BUG();
	117	}
	118	EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
	119
22b7050a MT	120	static void __virtio_config_changed(struct virtio_device *dev)
	121	{
	122	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
	123
	124	if (!dev->config_enabled)
	125	dev->config_change_pending = true;
	126	else if (drv && drv->config_changed)
	127	drv->config_changed(dev);
	128	}
	129
	130	void virtio_config_changed(struct virtio_device *dev)
	131	{
	132	unsigned long flags;
	133
	134	spin_lock_irqsave(&dev->config_lock, flags);
	135	__virtio_config_changed(dev);
	136	spin_unlock_irqrestore(&dev->config_lock, flags);
	137	}
	138	EXPORT_SYMBOL_GPL(virtio_config_changed);
	139
	140	static void virtio_config_disable(struct virtio_device *dev)
	141	{
	142	spin_lock_irq(&dev->config_lock);
	143	dev->config_enabled = false;
	144	spin_unlock_irq(&dev->config_lock);
	145	}
	146
	147	static void virtio_config_enable(struct virtio_device *dev)
	148	{
	149	spin_lock_irq(&dev->config_lock);
	150	dev->config_enabled = true;
	151	if (dev->config_change_pending)
	152	__virtio_config_changed(dev);
	153	dev->config_change_pending = false;
	154	spin_unlock_irq(&dev->config_lock);
	155	}
	156
ec3d41c4 RR	157	static int virtio_dev_probe(struct device *_d)
ec3d41c4 RR	158	{
c45a6816	159	int err, i;
9bffdca8	160	struct virtio_device *dev = dev_to_virtio(_d);
9a2bdcc8	161	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
c45a6816	162	u32 device_features;
ec3d41c4	163
c45a6816	164	/* We have a driver! */
ec3d41c4	165	add_status(dev, VIRTIO_CONFIG_S_DRIVER);
c45a6816 RR	166
	167	/* Figure out what features the device supports. */
	168	device_features = dev->config->get_features(dev);
	169
	170	/* Features supported by both device and driver into dev->features. */
	171	memset(dev->features, 0, sizeof(dev->features));
	172	for (i = 0; i < drv->feature_table_size; i++) {
	173	unsigned int f = drv->feature_table[i];
	174	BUG_ON(f >= 32);
	175	if (device_features & (1 << f))
	176	set_bit(f, dev->features);
	177	}
	178
c624896e	179	/* Transport features always preserved to pass to finalize_features. */
dd7c7bc4 RR	180	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
	181	if (device_features & (1 << i))
	182	set_bit(i, dev->features);
	183
ef688e15 RR	184	dev->config->finalize_features(dev);
ef688e15 RR	185
ec3d41c4 RR	186	err = drv->probe(dev);
	187	if (err)
	188	add_status(dev, VIRTIO_CONFIG_S_FAILED);
59057fbc	189	else {
b92dea67	190	add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
59057fbc NB	191	if (drv->scan)
59057fbc NB	192	drv->scan(dev);
22b7050a MT	193
22b7050a MT	194	virtio_config_enable(dev);
59057fbc	195	}
ef688e15	196
ec3d41c4 RR	197	return err;
	198	}
	199
74b2553f RR	200	static int virtio_dev_remove(struct device *_d)
74b2553f RR	201	{
9bffdca8	202	struct virtio_device *dev = dev_to_virtio(_d);
9a2bdcc8	203	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
74b2553f	204
22b7050a MT	205	virtio_config_disable(dev);
22b7050a MT	206
74b2553f	207	drv->remove(dev);
6e5aa7ef RR	208
6e5aa7ef RR	209	/* Driver should have reset device. */
5543a6ac	210	WARN_ON_ONCE(dev->config->get_status(dev));
6e5aa7ef RR	211
	212	/* Acknowledge the device's existence again. */
	213	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
74b2553f RR	214	return 0;
	215	}
	216
e962fa66 MM	217	static struct bus_type virtio_bus = {
	218	.name = "virtio",
	219	.match = virtio_dev_match,
3736dab6	220	.dev_groups = virtio_dev_groups,
e962fa66 MM	221	.uevent = virtio_uevent,
	222	.probe = virtio_dev_probe,
	223	.remove = virtio_dev_remove,
	224	};
	225
ec3d41c4 RR	226	int register_virtio_driver(struct virtio_driver *driver)
ec3d41c4 RR	227	{
c45a6816 RR	228	/* Catch this early. */
c45a6816 RR	229	BUG_ON(driver->feature_table_size && !driver->feature_table);
ec3d41c4	230	driver->driver.bus = &virtio_bus;
ec3d41c4 RR	231	return driver_register(&driver->driver);
	232	}
	233	EXPORT_SYMBOL_GPL(register_virtio_driver);
	234
	235	void unregister_virtio_driver(struct virtio_driver *driver)
	236	{
	237	driver_unregister(&driver->driver);
	238	}
	239	EXPORT_SYMBOL_GPL(unregister_virtio_driver);
	240
	241	int register_virtio_device(struct virtio_device *dev)
	242	{
	243	int err;
	244
	245	dev->dev.bus = &virtio_bus;
b769f579 RR	246
b769f579 RR	247	/* Assign a unique device index and hence name. */
90e03207 AH	248	err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
	249	if (err < 0)
	250	goto out;
	251
	252	dev->index = err;
99e0b6c8	253	dev_set_name(&dev->dev, "virtio%u", dev->index);
ec3d41c4	254
22b7050a MT	255	spin_lock_init(&dev->config_lock);
	256	dev->config_enabled = false;
	257	dev->config_change_pending = false;
	258
6e5aa7ef RR	259	/* We always start by resetting the device, in case a previous
	260	* driver messed it up. This also tests that code path a little. */
	261	dev->config->reset(dev);
	262
ec3d41c4 RR	263	/* Acknowledge that we've seen the device. */
	264	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
	265
9499f5e7 RR	266	INIT_LIST_HEAD(&dev->vqs);
9499f5e7 RR	267
ec3d41c4 RR	268	/* device_register() causes the bus infrastructure to look for a
	269	* matching driver. */
	270	err = device_register(&dev->dev);
90e03207	271	out:
ec3d41c4 RR	272	if (err)
	273	add_status(dev, VIRTIO_CONFIG_S_FAILED);
	274	return err;
	275	}
	276	EXPORT_SYMBOL_GPL(register_virtio_device);
	277
	278	void unregister_virtio_device(struct virtio_device *dev)
	279	{
237242bd CH	280	int index = dev->index; /* save for after device release */
237242bd CH	281
ec3d41c4	282	device_unregister(&dev->dev);
237242bd	283	ida_simple_remove(&virtio_index_ida, index);
ec3d41c4 RR	284	}
	285	EXPORT_SYMBOL_GPL(unregister_virtio_device);
	286
c6716bae MT	287	#ifdef CONFIG_PM_SLEEP
	288	int virtio_device_freeze(struct virtio_device *dev)
	289	{
	290	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
	291
22b7050a MT	292	virtio_config_disable(dev);
22b7050a MT	293
c6716bae MT	294	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
	295
	296	if (drv && drv->freeze)
	297	return drv->freeze(dev);
	298
	299	return 0;
	300	}
	301	EXPORT_SYMBOL_GPL(virtio_device_freeze);
	302
	303	int virtio_device_restore(struct virtio_device *dev)
	304	{
	305	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
	306
	307	/* We always start by resetting the device, in case a previous
	308	* driver messed it up. */
	309	dev->config->reset(dev);
	310
	311	/* Acknowledge that we've seen the device. */
	312	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
	313
	314	/* Maybe driver failed before freeze.
	315	* Restore the failed status, for debugging. */
	316	if (dev->failed)
	317	add_status(dev, VIRTIO_CONFIG_S_FAILED);
	318
	319	if (!drv)
	320	return 0;
	321
	322	/* We have a driver! */
	323	add_status(dev, VIRTIO_CONFIG_S_DRIVER);
	324
	325	dev->config->finalize_features(dev);
	326
	327	if (drv->restore) {
	328	int ret = drv->restore(dev);
	329	if (ret) {
	330	add_status(dev, VIRTIO_CONFIG_S_FAILED);
	331	return ret;
	332	}
	333	}
	334
	335	/* Finally, tell the device we're all set */
	336	add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
	337
22b7050a MT	338	virtio_config_enable(dev);
22b7050a MT	339
c6716bae MT	340	return 0;
	341	}
	342	EXPORT_SYMBOL_GPL(virtio_device_restore);
	343	#endif
	344
ec3d41c4 RR	345	static int virtio_init(void)
	346	{
	347	if (bus_register(&virtio_bus) != 0)
	348	panic("virtio bus registration failed");
	349	return 0;
	350	}
c6fd4701 RR	351
	352	static void __exit virtio_exit(void)
	353	{
	354	bus_unregister(&virtio_bus);
	355	}
ec3d41c4	356	core_initcall(virtio_init);
c6fd4701 RR	357	module_exit(virtio_exit);
	358
	359	MODULE_LICENSE("GPL");