drivers/virtio/virtio.c

   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 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 }
  22 static 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 }
  28 static 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 }
  35 static 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 }
  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
  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(). */
  70 static 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
  83 static 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
  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
  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 = 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 }
 107 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
 108
 109 static 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
 150 static 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
 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
 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
 183 void unregister_virtio_driver(struct virtio_driver *driver)
 184 {
 185         driver_unregister(&driver->driver);
 186 }
 187 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 188
 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         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);
 215 out:
 216         if (err)
 217                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 218         return err;
 219 }
 220 EXPORT_SYMBOL_GPL(register_virtio_device);
 221
 222 void 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 }
 229 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 230
 231 static int virtio_init(void)
 232 {
 233         if (bus_register(&virtio_bus) != 0)
 234                 panic("virtio bus registration failed");
 235         return 0;
 236 }
 237
 238 static void __exit virtio_exit(void)
 239 {
 240         bus_unregister(&virtio_bus);
 241 }
 242 core_initcall(virtio_init);
 243 module_exit(virtio_exit);
 244
 245 MODULE_LICENSE("GPL");