drivers/virtio/virtio.c

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