1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/virtio.h>
3 #include <linux/spinlock.h>
4 #include <linux/virtio_config.h>
5 #include <linux/module.h>
8 #include <linux/platform-feature.h>
9 #include <uapi/linux/virtio_ids.h>
11 /* Unique numbering for virtio devices. */
12 static DEFINE_IDA(virtio_index_ida);
14 static ssize_t device_show(struct device *_d,
15 struct device_attribute *attr, char *buf)
17 struct virtio_device *dev = dev_to_virtio(_d);
18 return sprintf(buf, "0x%04x\n", dev->id.device);
20 static DEVICE_ATTR_RO(device);
22 static ssize_t vendor_show(struct device *_d,
23 struct device_attribute *attr, char *buf)
25 struct virtio_device *dev = dev_to_virtio(_d);
26 return sprintf(buf, "0x%04x\n", dev->id.vendor);
28 static DEVICE_ATTR_RO(vendor);
30 static ssize_t status_show(struct device *_d,
31 struct device_attribute *attr, char *buf)
33 struct virtio_device *dev = dev_to_virtio(_d);
34 return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
36 static DEVICE_ATTR_RO(status);
38 static ssize_t modalias_show(struct device *_d,
39 struct device_attribute *attr, char *buf)
41 struct virtio_device *dev = dev_to_virtio(_d);
42 return sprintf(buf, "virtio:d%08Xv%08X\n",
43 dev->id.device, dev->id.vendor);
45 static DEVICE_ATTR_RO(modalias);
47 static ssize_t features_show(struct device *_d,
48 struct device_attribute *attr, char *buf)
50 struct virtio_device *dev = dev_to_virtio(_d);
54 /* We actually represent this as a bitstring, as it could be
55 * arbitrary length in future. */
56 for (i = 0; i < sizeof(dev->features)*8; i++)
57 len += sprintf(buf+len, "%c",
58 __virtio_test_bit(dev, i) ? '1' : '0');
59 len += sprintf(buf+len, "\n");
62 static DEVICE_ATTR_RO(features);
64 static struct attribute *virtio_dev_attrs[] = {
65 &dev_attr_device.attr,
66 &dev_attr_vendor.attr,
67 &dev_attr_status.attr,
68 &dev_attr_modalias.attr,
69 &dev_attr_features.attr,
72 ATTRIBUTE_GROUPS(virtio_dev);
74 static inline int virtio_id_match(const struct virtio_device *dev,
75 const struct virtio_device_id *id)
77 if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
80 return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
83 /* This looks through all the IDs a driver claims to support. If any of them
84 * match, we return 1 and the kernel will call virtio_dev_probe(). */
85 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
88 struct virtio_device *dev = dev_to_virtio(_dv);
89 const struct virtio_device_id *ids;
91 ids = drv_to_virtio(_dr)->id_table;
92 for (i = 0; ids[i].device; i++)
93 if (virtio_id_match(dev, &ids[i]))
98 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
100 struct virtio_device *dev = dev_to_virtio(_dv);
102 return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
103 dev->id.device, dev->id.vendor);
106 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
110 struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
112 for (i = 0; i < drv->feature_table_size; i++)
113 if (drv->feature_table[i] == fbit)
116 if (drv->feature_table_legacy) {
117 for (i = 0; i < drv->feature_table_size_legacy; i++)
118 if (drv->feature_table_legacy[i] == fbit)
124 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
126 static void __virtio_config_changed(struct virtio_device *dev)
128 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
130 if (!dev->config_enabled)
131 dev->config_change_pending = true;
132 else if (drv && drv->config_changed)
133 drv->config_changed(dev);
136 void virtio_config_changed(struct virtio_device *dev)
140 spin_lock_irqsave(&dev->config_lock, flags);
141 __virtio_config_changed(dev);
142 spin_unlock_irqrestore(&dev->config_lock, flags);
144 EXPORT_SYMBOL_GPL(virtio_config_changed);
146 static void virtio_config_disable(struct virtio_device *dev)
148 spin_lock_irq(&dev->config_lock);
149 dev->config_enabled = false;
150 spin_unlock_irq(&dev->config_lock);
153 static void virtio_config_enable(struct virtio_device *dev)
155 spin_lock_irq(&dev->config_lock);
156 dev->config_enabled = true;
157 if (dev->config_change_pending)
158 __virtio_config_changed(dev);
159 dev->config_change_pending = false;
160 spin_unlock_irq(&dev->config_lock);
163 void virtio_add_status(struct virtio_device *dev, unsigned int status)
166 dev->config->set_status(dev, dev->config->get_status(dev) | status);
168 EXPORT_SYMBOL_GPL(virtio_add_status);
170 /* Do some validation, then set FEATURES_OK */
171 static int virtio_features_ok(struct virtio_device *dev)
177 if (platform_has(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS)) {
178 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
180 "device must provide VIRTIO_F_VERSION_1\n");
184 if (!virtio_has_feature(dev, VIRTIO_F_ACCESS_PLATFORM)) {
186 "device must provide VIRTIO_F_ACCESS_PLATFORM\n");
191 if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1))
194 virtio_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
195 status = dev->config->get_status(dev);
196 if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
197 dev_err(&dev->dev, "virtio: device refuses features: %x\n",
205 * virtio_reset_device - quiesce device for removal
206 * @dev: the device to reset
208 * Prevents device from sending interrupts and accessing memory.
210 * Generally used for cleanup during driver / device removal.
212 * Once this has been invoked, caller must ensure that
213 * virtqueue_notify / virtqueue_kick are not in progress.
215 * Note: this guarantees that vq callbacks are not in progress, however caller
216 * is responsible for preventing access from other contexts, such as a system
217 * call/workqueue/bh. Invoking virtio_break_device then flushing any such
218 * contexts is one way to handle that.
220 void virtio_reset_device(struct virtio_device *dev)
223 * The below virtio_synchronize_cbs() guarantees that any
224 * interrupt for this line arriving after
225 * virtio_synchronize_vqs() has completed is guaranteed to see
226 * vq->broken as true.
228 virtio_break_device(dev);
229 virtio_synchronize_cbs(dev);
231 dev->config->reset(dev);
233 EXPORT_SYMBOL_GPL(virtio_reset_device);
235 static int virtio_dev_probe(struct device *_d)
238 struct virtio_device *dev = dev_to_virtio(_d);
239 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
242 u64 driver_features_legacy;
244 /* We have a driver! */
245 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
247 /* Figure out what features the device supports. */
248 device_features = dev->config->get_features(dev);
250 /* Figure out what features the driver supports. */
252 for (i = 0; i < drv->feature_table_size; i++) {
253 unsigned int f = drv->feature_table[i];
255 driver_features |= (1ULL << f);
258 /* Some drivers have a separate feature table for virtio v1.0 */
259 if (drv->feature_table_legacy) {
260 driver_features_legacy = 0;
261 for (i = 0; i < drv->feature_table_size_legacy; i++) {
262 unsigned int f = drv->feature_table_legacy[i];
264 driver_features_legacy |= (1ULL << f);
267 driver_features_legacy = driver_features;
270 if (device_features & (1ULL << VIRTIO_F_VERSION_1))
271 dev->features = driver_features & device_features;
273 dev->features = driver_features_legacy & device_features;
275 /* Transport features always preserved to pass to finalize_features. */
276 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
277 if (device_features & (1ULL << i))
278 __virtio_set_bit(dev, i);
280 err = dev->config->finalize_features(dev);
285 u64 features = dev->features;
287 err = drv->validate(dev);
291 /* Did validation change any features? Then write them again. */
292 if (features != dev->features) {
293 err = dev->config->finalize_features(dev);
299 err = virtio_features_ok(dev);
303 err = drv->probe(dev);
307 /* If probe didn't do it, mark device DRIVER_OK ourselves. */
308 if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
309 virtio_device_ready(dev);
314 virtio_config_enable(dev);
318 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
323 static void virtio_dev_remove(struct device *_d)
325 struct virtio_device *dev = dev_to_virtio(_d);
326 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
328 virtio_config_disable(dev);
332 /* Driver should have reset device. */
333 WARN_ON_ONCE(dev->config->get_status(dev));
335 /* Acknowledge the device's existence again. */
336 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
338 of_node_put(dev->dev.of_node);
341 static struct bus_type virtio_bus = {
343 .match = virtio_dev_match,
344 .dev_groups = virtio_dev_groups,
345 .uevent = virtio_uevent,
346 .probe = virtio_dev_probe,
347 .remove = virtio_dev_remove,
350 int register_virtio_driver(struct virtio_driver *driver)
352 /* Catch this early. */
353 BUG_ON(driver->feature_table_size && !driver->feature_table);
354 driver->driver.bus = &virtio_bus;
355 return driver_register(&driver->driver);
357 EXPORT_SYMBOL_GPL(register_virtio_driver);
359 void unregister_virtio_driver(struct virtio_driver *driver)
361 driver_unregister(&driver->driver);
363 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
365 static int virtio_device_of_init(struct virtio_device *dev)
367 struct device_node *np, *pnode = dev_of_node(dev->dev.parent);
368 char compat[] = "virtio,deviceXXXXXXXX";
374 count = of_get_available_child_count(pnode);
378 /* There can be only 1 child node */
379 if (WARN_ON(count > 1))
382 np = of_get_next_available_child(pnode, NULL);
386 ret = snprintf(compat, sizeof(compat), "virtio,device%x", dev->id.device);
387 BUG_ON(ret >= sizeof(compat));
390 * On powerpc/pseries virtio devices are PCI devices so PCI
391 * vendor/device ids play the role of the "compatible" property.
392 * Simply don't init of_node in this case.
394 if (!of_device_is_compatible(np, compat)) {
399 dev->dev.of_node = np;
408 * register_virtio_device - register virtio device
409 * @dev : virtio device to be registered
411 * On error, the caller must call put_device on &@dev->dev (and not kfree),
412 * as another code path may have obtained a reference to @dev.
414 * Returns: 0 on suceess, -error on failure
416 int register_virtio_device(struct virtio_device *dev)
420 dev->dev.bus = &virtio_bus;
421 device_initialize(&dev->dev);
423 /* Assign a unique device index and hence name. */
424 err = ida_alloc(&virtio_index_ida, GFP_KERNEL);
429 dev_set_name(&dev->dev, "virtio%u", dev->index);
431 err = virtio_device_of_init(dev);
435 spin_lock_init(&dev->config_lock);
436 dev->config_enabled = false;
437 dev->config_change_pending = false;
439 INIT_LIST_HEAD(&dev->vqs);
440 spin_lock_init(&dev->vqs_list_lock);
442 /* We always start by resetting the device, in case a previous
443 * driver messed it up. This also tests that code path a little. */
444 virtio_reset_device(dev);
446 /* Acknowledge that we've seen the device. */
447 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
450 * device_add() causes the bus infrastructure to look for a matching
453 err = device_add(&dev->dev);
455 goto out_of_node_put;
460 of_node_put(dev->dev.of_node);
462 ida_free(&virtio_index_ida, dev->index);
464 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
467 EXPORT_SYMBOL_GPL(register_virtio_device);
469 bool is_virtio_device(struct device *dev)
471 return dev->bus == &virtio_bus;
473 EXPORT_SYMBOL_GPL(is_virtio_device);
475 void unregister_virtio_device(struct virtio_device *dev)
477 int index = dev->index; /* save for after device release */
479 device_unregister(&dev->dev);
480 ida_free(&virtio_index_ida, index);
482 EXPORT_SYMBOL_GPL(unregister_virtio_device);
484 #ifdef CONFIG_PM_SLEEP
485 int virtio_device_freeze(struct virtio_device *dev)
487 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
489 virtio_config_disable(dev);
491 dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
493 if (drv && drv->freeze)
494 return drv->freeze(dev);
498 EXPORT_SYMBOL_GPL(virtio_device_freeze);
500 int virtio_device_restore(struct virtio_device *dev)
502 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
505 /* We always start by resetting the device, in case a previous
506 * driver messed it up. */
507 virtio_reset_device(dev);
509 /* Acknowledge that we've seen the device. */
510 virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
512 /* Maybe driver failed before freeze.
513 * Restore the failed status, for debugging. */
515 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
520 /* We have a driver! */
521 virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER);
523 ret = dev->config->finalize_features(dev);
527 ret = virtio_features_ok(dev);
532 ret = drv->restore(dev);
537 /* If restore didn't do it, mark device DRIVER_OK ourselves. */
538 if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
539 virtio_device_ready(dev);
541 virtio_config_enable(dev);
546 virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
549 EXPORT_SYMBOL_GPL(virtio_device_restore);
552 static int virtio_init(void)
554 if (bus_register(&virtio_bus) != 0)
555 panic("virtio bus registration failed");
559 static void __exit virtio_exit(void)
561 bus_unregister(&virtio_bus);
562 ida_destroy(&virtio_index_ida);
564 core_initcall(virtio_init);
565 module_exit(virtio_exit);
567 MODULE_LICENSE("GPL");