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 struct bus_type virtio_bus = {
  75         .name  = "virtio",
  76         .match = virtio_dev_match,
  77         .dev_attrs = virtio_dev_attrs,
  78         .uevent = virtio_uevent,
  79 };
  80
  81 static void add_status(struct virtio_device *dev, unsigned status)
  82 {
  83         dev->config->set_status(dev, dev->config->get_status(dev) | status);
  84 }
  85
  86 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
  87                                          unsigned int fbit)
  88 {
  89         unsigned int i;
  90         struct virtio_driver *drv = container_of(vdev->dev.driver,
  91                                                  struct virtio_driver, driver);
  92
  93         for (i = 0; i < drv->feature_table_size; i++)
  94                 if (drv->feature_table[i] == fbit)
  95                         return;
  96         BUG();
  97 }
  98 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
  99
 100 static int virtio_dev_probe(struct device *_d)
 101 {
 102         int err, i;
 103         struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
 104         struct virtio_driver *drv = container_of(dev->dev.driver,
 105                                                  struct virtio_driver, driver);
 106         u32 device_features;
 107
 108         /* We have a driver! */
 109         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 110
 111         /* Figure out what features the device supports. */
 112         device_features = dev->config->get_features(dev);
 113
 114         /* Features supported by both device and driver into dev->features. */
 115         memset(dev->features, 0, sizeof(dev->features));
 116         for (i = 0; i < drv->feature_table_size; i++) {
 117                 unsigned int f = drv->feature_table[i];
 118                 BUG_ON(f >= 32);
 119                 if (device_features & (1 << f))
 120                         set_bit(f, dev->features);
 121         }
 122
 123         err = drv->probe(dev);
 124         if (err)
 125                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 126         else {
 127                 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 128                 /* They should never have set feature bits beyond 32 */
 129                 dev->config->set_features(dev, dev->features[0]);
 130         }
 131         return err;
 132 }
 133
 134 static int virtio_dev_remove(struct device *_d)
 135 {
 136         struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
 137         struct virtio_driver *drv = container_of(dev->dev.driver,
 138                                                  struct virtio_driver, driver);
 139
 140         drv->remove(dev);
 141
 142         /* Driver should have reset device. */
 143         BUG_ON(dev->config->get_status(dev));
 144
 145         /* Acknowledge the device's existence again. */
 146         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 147         return 0;
 148 }
 149
 150 int register_virtio_driver(struct virtio_driver *driver)
 151 {
 152         /* Catch this early. */
 153         BUG_ON(driver->feature_table_size && !driver->feature_table);
 154         driver->driver.bus = &virtio_bus;
 155         driver->driver.probe = virtio_dev_probe;
 156         driver->driver.remove = virtio_dev_remove;
 157         return driver_register(&driver->driver);
 158 }
 159 EXPORT_SYMBOL_GPL(register_virtio_driver);
 160
 161 void unregister_virtio_driver(struct virtio_driver *driver)
 162 {
 163         driver_unregister(&driver->driver);
 164 }
 165 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 166
 167 int register_virtio_device(struct virtio_device *dev)
 168 {
 169         int err;
 170
 171         dev->dev.bus = &virtio_bus;
 172
 173         /* Assign a unique device index and hence name. */
 174         dev->index = dev_index++;
 175         sprintf(dev->dev.bus_id, "virtio%u", dev->index);
 176
 177         /* We always start by resetting the device, in case a previous
 178          * driver messed it up.  This also tests that code path a little. */
 179         dev->config->reset(dev);
 180
 181         /* Acknowledge that we've seen the device. */
 182         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 183
 184         /* device_register() causes the bus infrastructure to look for a
 185          * matching driver. */
 186         err = device_register(&dev->dev);
 187         if (err)
 188                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 189         return err;
 190 }
 191 EXPORT_SYMBOL_GPL(register_virtio_device);
 192
 193 void unregister_virtio_device(struct virtio_device *dev)
 194 {
 195         device_unregister(&dev->dev);
 196 }
 197 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 198
 199 static int virtio_init(void)
 200 {
 201         if (bus_register(&virtio_bus) != 0)
 202                 panic("virtio bus registration failed");
 203         return 0;
 204 }
 205
 206 static void __exit virtio_exit(void)
 207 {
 208         bus_unregister(&virtio_bus);
 209 }
 210 core_initcall(virtio_init);
 211 module_exit(virtio_exit);
 212
 213 MODULE_LICENSE("GPL");