Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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 ssize_t vendor_show(struct device *_d,
17 struct device_attribute *attr, char *buf)
18{
19 struct virtio_device *dev = dev_to_virtio(_d);
20 return sprintf(buf, "0x%04x\n", dev->id.vendor);
21}
22static ssize_t status_show(struct device *_d,
23 struct device_attribute *attr, char *buf)
24{
25 struct virtio_device *dev = dev_to_virtio(_d);
26 return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
27}
28static ssize_t modalias_show(struct device *_d,
29 struct device_attribute *attr, char *buf)
30{
31 struct virtio_device *dev = dev_to_virtio(_d);
32 return sprintf(buf, "virtio:d%08Xv%08X\n",
33 dev->id.device, dev->id.vendor);
34}
35static ssize_t features_show(struct device *_d,
36 struct device_attribute *attr, char *buf)
37{
38 struct virtio_device *dev = dev_to_virtio(_d);
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}
50static 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
59static 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(). */
70static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
71{
72 unsigned int i;
73 struct virtio_device *dev = dev_to_virtio(_dv);
74 const struct virtio_device_id *ids;
75
76 ids = drv_to_virtio(_dr)->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
83static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
84{
85 struct virtio_device *dev = dev_to_virtio(_dv);
86
87 return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
88 dev->id.device, dev->id.vendor);
89}
90
91static void add_status(struct virtio_device *dev, unsigned status)
92{
93 dev->config->set_status(dev, dev->config->get_status(dev) | status);
94}
95
96void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
97 unsigned int fbit)
98{
99 unsigned int i;
100 struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
101
102 for (i = 0; i < drv->feature_table_size; i++)
103 if (drv->feature_table[i] == fbit)
104 return;
105 BUG();
106}
107EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
108
109static int virtio_dev_probe(struct device *_d)
110{
111 int err, i;
112 struct virtio_device *dev = dev_to_virtio(_d);
113 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
114 u32 device_features;
115
116 /* We have a driver! */
117 add_status(dev, VIRTIO_CONFIG_S_DRIVER);
118
119 /* Figure out what features the device supports. */
120 device_features = dev->config->get_features(dev);
121
122 /* Features supported by both device and driver into dev->features. */
123 memset(dev->features, 0, sizeof(dev->features));
124 for (i = 0; i < drv->feature_table_size; i++) {
125 unsigned int f = drv->feature_table[i];
126 BUG_ON(f >= 32);
127 if (device_features & (1 << f))
128 set_bit(f, dev->features);
129 }
130
131 /* Transport features always preserved to pass to finalize_features. */
132 for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
133 if (device_features & (1 << i))
134 set_bit(i, dev->features);
135
136 dev->config->finalize_features(dev);
137
138 err = drv->probe(dev);
139 if (err)
140 add_status(dev, VIRTIO_CONFIG_S_FAILED);
141 else {
142 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
143 if (drv->scan)
144 drv->scan(dev);
145 }
146
147 return err;
148}
149
150static int virtio_dev_remove(struct device *_d)
151{
152 struct virtio_device *dev = dev_to_virtio(_d);
153 struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
154
155 drv->remove(dev);
156
157 /* Driver should have reset device. */
158 WARN_ON_ONCE(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
165static 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
174int 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}
181EXPORT_SYMBOL_GPL(register_virtio_driver);
182
183void unregister_virtio_driver(struct virtio_driver *driver)
184{
185 driver_unregister(&driver->driver);
186}
187EXPORT_SYMBOL_GPL(unregister_virtio_driver);
188
189int 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 err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
197 if (err < 0)
198 goto out;
199
200 dev->index = err;
201 dev_set_name(&dev->dev, "virtio%u", dev->index);
202
203 /* We always start by resetting the device, in case a previous
204 * driver messed it up. This also tests that code path a little. */
205 dev->config->reset(dev);
206
207 /* Acknowledge that we've seen the device. */
208 add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
209
210 INIT_LIST_HEAD(&dev->vqs);
211
212 /* device_register() causes the bus infrastructure to look for a
213 * matching driver. */
214 err = device_register(&dev->dev);
215out:
216 if (err)
217 add_status(dev, VIRTIO_CONFIG_S_FAILED);
218 return err;
219}
220EXPORT_SYMBOL_GPL(register_virtio_device);
221
222void unregister_virtio_device(struct virtio_device *dev)
223{
224 int index = dev->index; /* save for after device release */
225
226 device_unregister(&dev->dev);
227 ida_simple_remove(&virtio_index_ida, index);
228}
229EXPORT_SYMBOL_GPL(unregister_virtio_device);
230
231static int virtio_init(void)
232{
233 if (bus_register(&virtio_bus) != 0)
234 panic("virtio bus registration failed");
235 return 0;
236}
237
238static void __exit virtio_exit(void)
239{
240 bus_unregister(&virtio_bus);
241}
242core_initcall(virtio_init);
243module_exit(virtio_exit);
244
245MODULE_LICENSE("GPL");