drivers/virtio/virtio.c

   1 #include <linux/virtio.h>
   2 #include <linux/spinlock.h>
   3 #include <linux/virtio_config.h>
   4
   5 /* Unique numbering for virtio devices. */
   6 static unsigned int dev_index;
   7
   8 static ssize_t device_show(struct device *_d,
   9                            struct device_attribute *attr, char *buf)
  10 {
  11         struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
  12         return sprintf(buf, "%hu", dev->id.device);
  13 }
  14 static ssize_t vendor_show(struct device *_d,
  15                            struct device_attribute *attr, char *buf)
  16 {
  17         struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
  18         return sprintf(buf, "%hu", dev->id.vendor);
  19 }
  20 static ssize_t status_show(struct device *_d,
  21                            struct device_attribute *attr, char *buf)
  22 {
  23         struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
  24         return sprintf(buf, "0x%08x", dev->config->get_status(dev));
  25 }
  26 static ssize_t modalias_show(struct device *_d,
  27                              struct device_attribute *attr, char *buf)
  28 {
  29         struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
  30
  31         return sprintf(buf, "virtio:d%08Xv%08X\n",
  32                        dev->id.device, dev->id.vendor);
  33 }
  34 static struct device_attribute virtio_dev_attrs[] = {
  35         __ATTR_RO(device),
  36         __ATTR_RO(vendor),
  37         __ATTR_RO(status),
  38         __ATTR_RO(modalias),
  39         __ATTR_NULL
  40 };
  41
  42 static inline int virtio_id_match(const struct virtio_device *dev,
  43                                   const struct virtio_device_id *id)
  44 {
  45         if (id->device != dev->id.device)
  46                 return 0;
  47
  48         return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor != dev->id.vendor;
  49 }
  50
  51 /* This looks through all the IDs a driver claims to support.  If any of them
  52  * match, we return 1 and the kernel will call virtio_dev_probe(). */
  53 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
  54 {
  55         unsigned int i;
  56         struct virtio_device *dev = container_of(_dv,struct virtio_device,dev);
  57         const struct virtio_device_id *ids;
  58
  59         ids = container_of(_dr, struct virtio_driver, driver)->id_table;
  60         for (i = 0; ids[i].device; i++)
  61                 if (virtio_id_match(dev, &ids[i]))
  62                         return 1;
  63         return 0;
  64 }
  65
  66 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
  67 {
  68         struct virtio_device *dev = container_of(_dv,struct virtio_device,dev);
  69
  70         return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
  71                               dev->id.device, dev->id.vendor);
  72 }
  73
  74 static void add_status(struct virtio_device *dev, unsigned status)
  75 {
  76         dev->config->set_status(dev, dev->config->get_status(dev) | status);
  77 }
  78
  79 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
  80                                          unsigned int fbit)
  81 {
  82         unsigned int i;
  83         struct virtio_driver *drv = container_of(vdev->dev.driver,
  84                                                  struct virtio_driver, driver);
  85
  86         for (i = 0; i < drv->feature_table_size; i++)
  87                 if (drv->feature_table[i] == fbit)
  88                         return;
  89         BUG();
  90 }
  91 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
  92
  93 static int virtio_dev_probe(struct device *_d)
  94 {
  95         int err, i;
  96         struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
  97         struct virtio_driver *drv = container_of(dev->dev.driver,
  98                                                  struct virtio_driver, driver);
  99         u32 device_features;
 100
 101         /* We have a driver! */
 102         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 103
 104         /* Figure out what features the device supports. */
 105         device_features = dev->config->get_features(dev);
 106
 107         /* Features supported by both device and driver into dev->features. */
 108         memset(dev->features, 0, sizeof(dev->features));
 109         for (i = 0; i < drv->feature_table_size; i++) {
 110                 unsigned int f = drv->feature_table[i];
 111                 BUG_ON(f >= 32);
 112                 if (device_features & (1 << f))
 113                         set_bit(f, dev->features);
 114         }
 115
 116         /* Transport features are always preserved to pass to set_features. */
 117         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 118                 if (device_features & (1 << i))
 119                         set_bit(i, dev->features);
 120
 121         err = drv->probe(dev);
 122         if (err)
 123                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 124         else {
 125                 /* They should never have set feature bits beyond 32 */
 126                 dev->config->set_features(dev, dev->features[0]);
 127                 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 128         }
 129         return err;
 130 }
 131
 132 static int virtio_dev_remove(struct device *_d)
 133 {
 134         struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
 135         struct virtio_driver *drv = container_of(dev->dev.driver,
 136                                                  struct virtio_driver, driver);
 137
 138         drv->remove(dev);
 139
 140         /* Driver should have reset device. */
 141         BUG_ON(dev->config->get_status(dev));
 142
 143         /* Acknowledge the device's existence again. */
 144         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 145         return 0;
 146 }
 147
 148 static struct bus_type virtio_bus = {
 149         .name  = "virtio",
 150         .match = virtio_dev_match,
 151         .dev_attrs = virtio_dev_attrs,
 152         .uevent = virtio_uevent,
 153         .probe = virtio_dev_probe,
 154         .remove = virtio_dev_remove,
 155 };
 156
 157 int register_virtio_driver(struct virtio_driver *driver)
 158 {
 159         /* Catch this early. */
 160         BUG_ON(driver->feature_table_size && !driver->feature_table);
 161         driver->driver.bus = &virtio_bus;
 162         return driver_register(&driver->driver);
 163 }
 164 EXPORT_SYMBOL_GPL(register_virtio_driver);
 165
 166 void unregister_virtio_driver(struct virtio_driver *driver)
 167 {
 168         driver_unregister(&driver->driver);
 169 }
 170 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 171
 172 int register_virtio_device(struct virtio_device *dev)
 173 {
 174         int err;
 175
 176         dev->dev.bus = &virtio_bus;
 177
 178         /* Assign a unique device index and hence name. */
 179         dev->index = dev_index++;
 180         sprintf(dev->dev.bus_id, "virtio%u", dev->index);
 181
 182         /* We always start by resetting the device, in case a previous
 183          * driver messed it up.  This also tests that code path a little. */
 184         dev->config->reset(dev);
 185
 186         /* Acknowledge that we've seen the device. */
 187         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 188
 189         /* device_register() causes the bus infrastructure to look for a
 190          * matching driver. */
 191         err = device_register(&dev->dev);
 192         if (err)
 193                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 194         return err;
 195 }
 196 EXPORT_SYMBOL_GPL(register_virtio_device);
 197
 198 void unregister_virtio_device(struct virtio_device *dev)
 199 {
 200         device_unregister(&dev->dev);
 201 }
 202 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 203
 204 static int virtio_init(void)
 205 {
 206         if (bus_register(&virtio_bus) != 0)
 207                 panic("virtio bus registration failed");
 208         return 0;
 209 }
 210
 211 static void __exit virtio_exit(void)
 212 {
 213         bus_unregister(&virtio_bus);
 214 }
 215 core_initcall(virtio_init);
 216 module_exit(virtio_exit);
 217
 218 MODULE_LICENSE("GPL");