1 #include <linux/virtio.h>
2 #include <linux/spinlock.h>
3 #include <linux/virtio_config.h>
4 #include <linux/module.h>
5
6 /* Unique numbering for virtio devices. */
7 static unsigned int dev_index;
8
device_show(struct device * _d,struct device_attribute * attr,char * buf)9 static ssize_t device_show(struct device *_d,
10 struct device_attribute *attr, char *buf)
11 {
12 struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
13 return sprintf(buf, "0x%04x\n", dev->id.device);
14 }
vendor_show(struct device * _d,struct device_attribute * attr,char * buf)15 static ssize_t vendor_show(struct device *_d,
16 struct device_attribute *attr, char *buf)
17 {
18 struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
19 return sprintf(buf, "0x%04x\n", dev->id.vendor);
20 }
status_show(struct device * _d,struct device_attribute * attr,char * buf)21 static ssize_t status_show(struct device *_d,
22 struct device_attribute *attr, char *buf)
23 {
24 struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
25 return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
26 }
modalias_show(struct device * _d,struct device_attribute * attr,char * buf)27 static ssize_t modalias_show(struct device *_d,
28 struct device_attribute *attr, char *buf)
29 {
30 struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
31
32 return sprintf(buf, "virtio:d%08Xv%08X\n",
33 dev->id.device, dev->id.vendor);
34 }
features_show(struct device * _d,struct device_attribute * attr,char * buf)35 static ssize_t features_show(struct device *_d,
36 struct device_attribute *attr, char *buf)
37 {
38 struct virtio_device *dev = container_of(_d, struct virtio_device, dev);
39 unsigned int i;
40 ssize_t len = 0;
41
42 /* We actually represent this as a bitstring, as it could be
43 * arbitrary length in future. */
44 for (i = 0; i < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++)
45 len += sprintf(buf+len, "%c",
46 test_bit(i, dev->features) ? '1' : '0');
47 len += sprintf(buf+len, "\n");
48 return len;
49 }
50 static struct device_attribute virtio_dev_attrs[] = {
51 __ATTR_RO(device),
52 __ATTR_RO(vendor),
53 __ATTR_RO(status),
54 __ATTR_RO(modalias),
55 __ATTR_RO(features),
56 __ATTR_NULL
57 };
58
virtio_id_match(const struct virtio_device * dev,const struct virtio_device_id * id)59 static inline int virtio_id_match(const struct virtio_device *dev,
60 const struct virtio_device_id *id)
61 {
62 if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
63 return 0;
64
65 return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
66 }
67
68 /* This looks through all the IDs a driver claims to support. If any of them
69 * match, we return 1 and the kernel will call virtio_dev_probe(). */
virtio_dev_match(struct device * _dv,struct device_driver * _dr)70 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
71 {
72 unsigned int i;
73 struct virtio_device *dev = container_of(_dv,struct virtio_device,dev);
74 const struct virtio_device_id *ids;
75
76 ids = container_of(_dr, struct virtio_driver, driver)->id_table;
77 for (i = 0; ids[i].device; i++)
78 if (virtio_id_match(dev, &ids[i]))
79 return 1;
80 return 0;
81 }
82
virtio_uevent(struct device * _dv,struct kobj_uevent_env * env)83 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
84 {
85 struct virtio_device *dev = container_of(_dv,struct virtio_device,dev);
86
87 return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
88 dev->id.device, dev->id.vendor);
89 }
90
add_status(struct virtio_device * dev,unsigned status)91 static void add_status(struct virtio_device *dev, unsigned status)
92 {
93 dev->config->set_status(dev, dev->config->get_status(dev) | status);
94 }
95
virtio_check_driver_offered_feature(const struct virtio_device * vdev,unsigned int fbit)96 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
97 unsigned int fbit)
98 {
99 unsigned int i;
100 struct virtio_driver *drv = container_of(vdev->dev.driver,
101 struct virtio_driver, driver);
102
103 for (i = 0; i < drv->feature_table_size; i++)
104 if (drv->feature_table[i] == fbit)
105 return;
106 BUG();
107 }
108 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
109
virtio_dev_probe(struct device * _d)110 static int virtio_dev_probe(struct device *_d)
111 {
112 int err, i;
113 struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
114 struct virtio_driver *drv = container_of(dev->dev.driver,
115 struct virtio_driver, driver);
116 u32 device_features;
117
118 /* We have a driver! */
119 add_status(dev, VIRTIO_CONFIG_S_DRIVER);
120
121 /* Figure out what features the device supports. */
122 device_features = dev->config->get_features(dev);
123
124 /* Features supported by both device and driver into dev->features. */
125 memset(dev->features, 0, sizeof(dev->features));
126 for (i = 0; i < drv->feature_table_size; i++) {
127 unsigned int f = drv->feature_table[i];
128 BUG_ON(f >= 32);
129 if (device_features & (1 << f))
130 set_bit(f, dev->features);
131 }
132
133 /* Transport features always preserved to pass to finalize_features. */
134 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
135 if (device_features & (1 << i))
136 set_bit(i, dev->features);
137
138 dev->config->finalize_features(dev);
139
140 err = drv->probe(dev);
141 if (err)
142 add_status(dev, VIRTIO_CONFIG_S_FAILED);
143 else
144 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
145
146 return err;
147 }
148
virtio_dev_remove(struct device * _d)149 static int virtio_dev_remove(struct device *_d)
150 {
151 struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
152 struct virtio_driver *drv = container_of(dev->dev.driver,
153 struct virtio_driver, driver);
154
155 drv->remove(dev);
156
157 /* Driver should have reset device. */
158 BUG_ON(dev->config->get_status(dev));
159
160 /* Acknowledge the device's existence again. */
161 add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
162 return 0;
163 }
164
165 static struct bus_type virtio_bus = {
166 .name = "virtio",
167 .match = virtio_dev_match,
168 .dev_attrs = virtio_dev_attrs,
169 .uevent = virtio_uevent,
170 .probe = virtio_dev_probe,
171 .remove = virtio_dev_remove,
172 };
173
register_virtio_driver(struct virtio_driver * driver)174 int register_virtio_driver(struct virtio_driver *driver)
175 {
176 /* Catch this early. */
177 BUG_ON(driver->feature_table_size && !driver->feature_table);
178 driver->driver.bus = &virtio_bus;
179 return driver_register(&driver->driver);
180 }
181 EXPORT_SYMBOL_GPL(register_virtio_driver);
182
unregister_virtio_driver(struct virtio_driver * driver)183 void unregister_virtio_driver(struct virtio_driver *driver)
184 {
185 driver_unregister(&driver->driver);
186 }
187 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
188
register_virtio_device(struct virtio_device * dev)189 int register_virtio_device(struct virtio_device *dev)
190 {
191 int err;
192
193 dev->dev.bus = &virtio_bus;
194
195 /* Assign a unique device index and hence name. */
196 dev->index = dev_index++;
197 dev_set_name(&dev->dev, "virtio%u", dev->index);
198
199 /* We always start by resetting the device, in case a previous
200 * driver messed it up. This also tests that code path a little. */
201 dev->config->reset(dev);
202
203 /* Acknowledge that we've seen the device. */
204 add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
205
206 INIT_LIST_HEAD(&dev->vqs);
207
208 /* device_register() causes the bus infrastructure to look for a
209 * matching driver. */
210 err = device_register(&dev->dev);
211 if (err)
212 add_status(dev, VIRTIO_CONFIG_S_FAILED);
213 return err;
214 }
215 EXPORT_SYMBOL_GPL(register_virtio_device);
216
unregister_virtio_device(struct virtio_device * dev)217 void unregister_virtio_device(struct virtio_device *dev)
218 {
219 device_unregister(&dev->dev);
220 }
221 EXPORT_SYMBOL_GPL(unregister_virtio_device);
222
virtio_init(void)223 static int virtio_init(void)
224 {
225 if (bus_register(&virtio_bus) != 0)
226 panic("virtio bus registration failed");
227 return 0;
228 }
229
virtio_exit(void)230 static void __exit virtio_exit(void)
231 {
232 bus_unregister(&virtio_bus);
233 }
234 core_initcall(virtio_init);
235 module_exit(virtio_exit);
236
237 MODULE_LICENSE("GPL");
238