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#include <uapi/linux/virtio_ids.h>
7
8/* Unique numbering for virtio devices. */
9static DEFINE_IDA(virtio_index_ida);
10
11static ssize_t device_show(struct device *_d,
12			   struct device_attribute *attr, char *buf)
13{
14	struct virtio_device *dev = dev_to_virtio(_d);
15	return sprintf(buf, "0x%04x\n", dev->id.device);
16}
17static DEVICE_ATTR_RO(device);
18
19static ssize_t vendor_show(struct device *_d,
20			   struct device_attribute *attr, char *buf)
21{
22	struct virtio_device *dev = dev_to_virtio(_d);
23	return sprintf(buf, "0x%04x\n", dev->id.vendor);
24}
25static DEVICE_ATTR_RO(vendor);
26
27static ssize_t status_show(struct device *_d,
28			   struct device_attribute *attr, char *buf)
29{
30	struct virtio_device *dev = dev_to_virtio(_d);
31	return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
32}
33static DEVICE_ATTR_RO(status);
34
35static ssize_t modalias_show(struct device *_d,
36			     struct device_attribute *attr, char *buf)
37{
38	struct virtio_device *dev = dev_to_virtio(_d);
39	return sprintf(buf, "virtio:d%08Xv%08X\n",
40		       dev->id.device, dev->id.vendor);
41}
42static DEVICE_ATTR_RO(modalias);
43
44static ssize_t features_show(struct device *_d,
45			     struct device_attribute *attr, char *buf)
46{
47	struct virtio_device *dev = dev_to_virtio(_d);
48	unsigned int i;
49	ssize_t len = 0;
50
51	/* We actually represent this as a bitstring, as it could be
52	 * arbitrary length in future. */
53	for (i = 0; i < sizeof(dev->features)*8; i++)
54		len += sprintf(buf+len, "%c",
55			       __virtio_test_bit(dev, i) ? '1' : '0');
56	len += sprintf(buf+len, "\n");
57	return len;
58}
59static DEVICE_ATTR_RO(features);
60
61static struct attribute *virtio_dev_attrs[] = {
62	&dev_attr_device.attr,
63	&dev_attr_vendor.attr,
64	&dev_attr_status.attr,
65	&dev_attr_modalias.attr,
66	&dev_attr_features.attr,
67	NULL,
68};
69ATTRIBUTE_GROUPS(virtio_dev);
70
71static inline int virtio_id_match(const struct virtio_device *dev,
72				  const struct virtio_device_id *id)
73{
74	if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
75		return 0;
76
77	return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
78}
79
80/* This looks through all the IDs a driver claims to support.  If any of them
81 * match, we return 1 and the kernel will call virtio_dev_probe(). */
82static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
83{
84	unsigned int i;
85	struct virtio_device *dev = dev_to_virtio(_dv);
86	const struct virtio_device_id *ids;
87
88	ids = drv_to_virtio(_dr)->id_table;
89	for (i = 0; ids[i].device; i++)
90		if (virtio_id_match(dev, &ids[i]))
91			return 1;
92	return 0;
93}
94
95static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
96{
97	struct virtio_device *dev = dev_to_virtio(_dv);
98
99	return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
100			      dev->id.device, dev->id.vendor);
101}
102
103static void add_status(struct virtio_device *dev, unsigned status)
104{
105	dev->config->set_status(dev, dev->config->get_status(dev) | status);
106}
107
108void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
109					 unsigned int fbit)
110{
111	unsigned int i;
112	struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
113
114	for (i = 0; i < drv->feature_table_size; i++)
115		if (drv->feature_table[i] == fbit)
116			return;
117
118	if (drv->feature_table_legacy) {
119		for (i = 0; i < drv->feature_table_size_legacy; i++)
120			if (drv->feature_table_legacy[i] == fbit)
121				return;
122	}
123
124	BUG();
125}
126EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
127
128static void __virtio_config_changed(struct virtio_device *dev)
129{
130	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
131
132	if (!dev->config_enabled)
133		dev->config_change_pending = true;
134	else if (drv && drv->config_changed)
135		drv->config_changed(dev);
136}
137
138void virtio_config_changed(struct virtio_device *dev)
139{
140	unsigned long flags;
141
142	spin_lock_irqsave(&dev->config_lock, flags);
143	__virtio_config_changed(dev);
144	spin_unlock_irqrestore(&dev->config_lock, flags);
145}
146EXPORT_SYMBOL_GPL(virtio_config_changed);
147
148static void virtio_config_disable(struct virtio_device *dev)
149{
150	spin_lock_irq(&dev->config_lock);
151	dev->config_enabled = false;
152	spin_unlock_irq(&dev->config_lock);
153}
154
155static void virtio_config_enable(struct virtio_device *dev)
156{
157	spin_lock_irq(&dev->config_lock);
158	dev->config_enabled = true;
159	if (dev->config_change_pending)
160		__virtio_config_changed(dev);
161	dev->config_change_pending = false;
162	spin_unlock_irq(&dev->config_lock);
163}
164
165static int virtio_finalize_features(struct virtio_device *dev)
166{
167	int ret = dev->config->finalize_features(dev);
168	unsigned status;
169
170	if (ret)
171		return ret;
172
173	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
174		return 0;
175
176	add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
177	status = dev->config->get_status(dev);
178	if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
179		dev_err(&dev->dev, "virtio: device refuses features: %x\n",
180			status);
181		return -ENODEV;
182	}
183	return 0;
184}
185
186static int virtio_dev_probe(struct device *_d)
187{
188	int err, i;
189	struct virtio_device *dev = dev_to_virtio(_d);
190	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
191	u64 device_features;
192	u64 driver_features;
193	u64 driver_features_legacy;
194
195	/* We have a driver! */
196	add_status(dev, VIRTIO_CONFIG_S_DRIVER);
197
198	/* Figure out what features the device supports. */
199	device_features = dev->config->get_features(dev);
200
201	/* Figure out what features the driver supports. */
202	driver_features = 0;
203	for (i = 0; i < drv->feature_table_size; i++) {
204		unsigned int f = drv->feature_table[i];
205		BUG_ON(f >= 64);
206		driver_features |= (1ULL << f);
207	}
208
209	/* Some drivers have a separate feature table for virtio v1.0 */
210	if (drv->feature_table_legacy) {
211		driver_features_legacy = 0;
212		for (i = 0; i < drv->feature_table_size_legacy; i++) {
213			unsigned int f = drv->feature_table_legacy[i];
214			BUG_ON(f >= 64);
215			driver_features_legacy |= (1ULL << f);
216		}
217	} else {
218		driver_features_legacy = driver_features;
219	}
220
221	if (device_features & (1ULL << VIRTIO_F_VERSION_1))
222		dev->features = driver_features & device_features;
223	else
224		dev->features = driver_features_legacy & device_features;
225
226	/* Transport features always preserved to pass to finalize_features. */
227	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
228		if (device_features & (1ULL << i))
229			__virtio_set_bit(dev, i);
230
231	err = virtio_finalize_features(dev);
232	if (err)
233		goto err;
234
235	err = drv->probe(dev);
236	if (err)
237		goto err;
238
239	/* If probe didn't do it, mark device DRIVER_OK ourselves. */
240	if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
241		virtio_device_ready(dev);
242
243	if (drv->scan)
244		drv->scan(dev);
245
246	virtio_config_enable(dev);
247
248	return 0;
249err:
250	add_status(dev, VIRTIO_CONFIG_S_FAILED);
251	return err;
252
253}
254
255static int virtio_dev_remove(struct device *_d)
256{
257	struct virtio_device *dev = dev_to_virtio(_d);
258	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
259
260	virtio_config_disable(dev);
261
262	drv->remove(dev);
263
264	/* Driver should have reset device. */
265	WARN_ON_ONCE(dev->config->get_status(dev));
266
267	/* Acknowledge the device's existence again. */
268	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
269	return 0;
270}
271
272static struct bus_type virtio_bus = {
273	.name  = "virtio",
274	.match = virtio_dev_match,
275	.dev_groups = virtio_dev_groups,
276	.uevent = virtio_uevent,
277	.probe = virtio_dev_probe,
278	.remove = virtio_dev_remove,
279};
280
281int register_virtio_driver(struct virtio_driver *driver)
282{
283	/* Catch this early. */
284	BUG_ON(driver->feature_table_size && !driver->feature_table);
285	driver->driver.bus = &virtio_bus;
286	return driver_register(&driver->driver);
287}
288EXPORT_SYMBOL_GPL(register_virtio_driver);
289
290void unregister_virtio_driver(struct virtio_driver *driver)
291{
292	driver_unregister(&driver->driver);
293}
294EXPORT_SYMBOL_GPL(unregister_virtio_driver);
295
296int register_virtio_device(struct virtio_device *dev)
297{
298	int err;
299
300	dev->dev.bus = &virtio_bus;
301
302	/* Assign a unique device index and hence name. */
303	err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
304	if (err < 0)
305		goto out;
306
307	dev->index = err;
308	dev_set_name(&dev->dev, "virtio%u", dev->index);
309
310	spin_lock_init(&dev->config_lock);
311	dev->config_enabled = false;
312	dev->config_change_pending = false;
313
314	/* We always start by resetting the device, in case a previous
315	 * driver messed it up.  This also tests that code path a little. */
316	dev->config->reset(dev);
317
318	/* Acknowledge that we've seen the device. */
319	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
320
321	INIT_LIST_HEAD(&dev->vqs);
322
323	/* device_register() causes the bus infrastructure to look for a
324	 * matching driver. */
325	err = device_register(&dev->dev);
326out:
327	if (err)
328		add_status(dev, VIRTIO_CONFIG_S_FAILED);
329	return err;
330}
331EXPORT_SYMBOL_GPL(register_virtio_device);
332
333void unregister_virtio_device(struct virtio_device *dev)
334{
335	int index = dev->index; /* save for after device release */
336
337	device_unregister(&dev->dev);
338	ida_simple_remove(&virtio_index_ida, index);
339}
340EXPORT_SYMBOL_GPL(unregister_virtio_device);
341
342#ifdef CONFIG_PM_SLEEP
343int virtio_device_freeze(struct virtio_device *dev)
344{
345	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
346
347	virtio_config_disable(dev);
348
349	dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
350
351	if (drv && drv->freeze)
352		return drv->freeze(dev);
353
354	return 0;
355}
356EXPORT_SYMBOL_GPL(virtio_device_freeze);
357
358int virtio_device_restore(struct virtio_device *dev)
359{
360	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
361	int ret;
362
363	/* We always start by resetting the device, in case a previous
364	 * driver messed it up. */
365	dev->config->reset(dev);
366
367	/* Acknowledge that we've seen the device. */
368	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
369
370	/* Maybe driver failed before freeze.
371	 * Restore the failed status, for debugging. */
372	if (dev->failed)
373		add_status(dev, VIRTIO_CONFIG_S_FAILED);
374
375	if (!drv)
376		return 0;
377
378	/* We have a driver! */
379	add_status(dev, VIRTIO_CONFIG_S_DRIVER);
380
381	ret = virtio_finalize_features(dev);
382	if (ret)
383		goto err;
384
385	if (drv->restore) {
386		ret = drv->restore(dev);
387		if (ret)
388			goto err;
389	}
390
391	/* Finally, tell the device we're all set */
392	add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
393
394	virtio_config_enable(dev);
395
396	return 0;
397
398err:
399	add_status(dev, VIRTIO_CONFIG_S_FAILED);
400	return ret;
401}
402EXPORT_SYMBOL_GPL(virtio_device_restore);
403#endif
404
405static int virtio_init(void)
406{
407	if (bus_register(&virtio_bus) != 0)
408		panic("virtio bus registration failed");
409	return 0;
410}
411
412static void __exit virtio_exit(void)
413{
414	bus_unregister(&virtio_bus);
415	ida_destroy(&virtio_index_ida);
416}
417core_initcall(virtio_init);
418module_exit(virtio_exit);
419
420MODULE_LICENSE("GPL");
421