xref: /openbmc/linux/drivers/virtio/virtio.c (revision 31b90347)
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 < 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 }
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 	BUG();
117 }
118 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
119 
120 static int virtio_dev_probe(struct device *_d)
121 {
122 	int err, i;
123 	struct virtio_device *dev = dev_to_virtio(_d);
124 	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
125 	u32 device_features;
126 
127 	/* We have a driver! */
128 	add_status(dev, VIRTIO_CONFIG_S_DRIVER);
129 
130 	/* Figure out what features the device supports. */
131 	device_features = dev->config->get_features(dev);
132 
133 	/* Features supported by both device and driver into dev->features. */
134 	memset(dev->features, 0, sizeof(dev->features));
135 	for (i = 0; i < drv->feature_table_size; i++) {
136 		unsigned int f = drv->feature_table[i];
137 		BUG_ON(f >= 32);
138 		if (device_features & (1 << f))
139 			set_bit(f, dev->features);
140 	}
141 
142 	/* Transport features always preserved to pass to finalize_features. */
143 	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
144 		if (device_features & (1 << i))
145 			set_bit(i, dev->features);
146 
147 	dev->config->finalize_features(dev);
148 
149 	err = drv->probe(dev);
150 	if (err)
151 		add_status(dev, VIRTIO_CONFIG_S_FAILED);
152 	else {
153 		add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
154 		if (drv->scan)
155 			drv->scan(dev);
156 	}
157 
158 	return err;
159 }
160 
161 static int virtio_dev_remove(struct device *_d)
162 {
163 	struct virtio_device *dev = dev_to_virtio(_d);
164 	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
165 
166 	drv->remove(dev);
167 
168 	/* Driver should have reset device. */
169 	WARN_ON_ONCE(dev->config->get_status(dev));
170 
171 	/* Acknowledge the device's existence again. */
172 	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
173 	return 0;
174 }
175 
176 static struct bus_type virtio_bus = {
177 	.name  = "virtio",
178 	.match = virtio_dev_match,
179 	.dev_groups = virtio_dev_groups,
180 	.uevent = virtio_uevent,
181 	.probe = virtio_dev_probe,
182 	.remove = virtio_dev_remove,
183 };
184 
185 int register_virtio_driver(struct virtio_driver *driver)
186 {
187 	/* Catch this early. */
188 	BUG_ON(driver->feature_table_size && !driver->feature_table);
189 	driver->driver.bus = &virtio_bus;
190 	return driver_register(&driver->driver);
191 }
192 EXPORT_SYMBOL_GPL(register_virtio_driver);
193 
194 void unregister_virtio_driver(struct virtio_driver *driver)
195 {
196 	driver_unregister(&driver->driver);
197 }
198 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
199 
200 int register_virtio_device(struct virtio_device *dev)
201 {
202 	int err;
203 
204 	dev->dev.bus = &virtio_bus;
205 
206 	/* Assign a unique device index and hence name. */
207 	err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
208 	if (err < 0)
209 		goto out;
210 
211 	dev->index = err;
212 	dev_set_name(&dev->dev, "virtio%u", dev->index);
213 
214 	/* We always start by resetting the device, in case a previous
215 	 * driver messed it up.  This also tests that code path a little. */
216 	dev->config->reset(dev);
217 
218 	/* Acknowledge that we've seen the device. */
219 	add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
220 
221 	INIT_LIST_HEAD(&dev->vqs);
222 
223 	/* device_register() causes the bus infrastructure to look for a
224 	 * matching driver. */
225 	err = device_register(&dev->dev);
226 out:
227 	if (err)
228 		add_status(dev, VIRTIO_CONFIG_S_FAILED);
229 	return err;
230 }
231 EXPORT_SYMBOL_GPL(register_virtio_device);
232 
233 void unregister_virtio_device(struct virtio_device *dev)
234 {
235 	int index = dev->index; /* save for after device release */
236 
237 	device_unregister(&dev->dev);
238 	ida_simple_remove(&virtio_index_ida, index);
239 }
240 EXPORT_SYMBOL_GPL(unregister_virtio_device);
241 
242 static int virtio_init(void)
243 {
244 	if (bus_register(&virtio_bus) != 0)
245 		panic("virtio bus registration failed");
246 	return 0;
247 }
248 
249 static void __exit virtio_exit(void)
250 {
251 	bus_unregister(&virtio_bus);
252 }
253 core_initcall(virtio_init);
254 module_exit(virtio_exit);
255 
256 MODULE_LICENSE("GPL");
257