Loading...
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. */
8static DEFINE_IDA(virtio_index_ida);
9
10static 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}
16static DEVICE_ATTR_RO(device);
17
18static 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}
24static DEVICE_ATTR_RO(vendor);
25
26static 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}
32static DEVICE_ATTR_RO(status);
33
34static 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}
41static DEVICE_ATTR_RO(modalias);
42
43static 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}
58static DEVICE_ATTR_RO(features);
59
60static 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};
68ATTRIBUTE_GROUPS(virtio_dev);
69
70static 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(). */
81static 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
94static 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
102static void add_status(struct virtio_device *dev, unsigned status)
103{
104 dev->config->set_status(dev, dev->config->get_status(dev) | status);
105}
106
107void 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}
118EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
119
120static 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
161static 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
176static 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
185int 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}
192EXPORT_SYMBOL_GPL(register_virtio_driver);
193
194void unregister_virtio_driver(struct virtio_driver *driver)
195{
196 driver_unregister(&driver->driver);
197}
198EXPORT_SYMBOL_GPL(unregister_virtio_driver);
199
200int 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);
226out:
227 if (err)
228 add_status(dev, VIRTIO_CONFIG_S_FAILED);
229 return err;
230}
231EXPORT_SYMBOL_GPL(register_virtio_device);
232
233void 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}
240EXPORT_SYMBOL_GPL(unregister_virtio_device);
241
242static int virtio_init(void)
243{
244 if (bus_register(&virtio_bus) != 0)
245 panic("virtio bus registration failed");
246 return 0;
247}
248
249static void __exit virtio_exit(void)
250{
251 bus_unregister(&virtio_bus);
252}
253core_initcall(virtio_init);
254module_exit(virtio_exit);
255
256MODULE_LICENSE("GPL");