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 ssize_t features_show(struct device *_d,
  35                              struct device_attribute *attr, char *buf)
  36 {
  37         struct virtio_device *dev = container_of(_d, struct virtio_device, dev);
  38         unsigned int i;
  39         ssize_t len = 0;
  40
  41         /* We actually represent this as a bitstring, as it could be
  42          * arbitrary length in future. */
  43         for (i = 0; i < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++)
  44                 len += sprintf(buf+len, "%c",
  45                                test_bit(i, dev->features) ? '1' : '0');
  46         len += sprintf(buf+len, "\n");
  47         return len;
  48 }
  49 static struct device_attribute virtio_dev_attrs[] = {
  50         __ATTR_RO(device),
  51         __ATTR_RO(vendor),
  52         __ATTR_RO(status),
  53         __ATTR_RO(modalias),
  54         __ATTR_RO(features),
  55         __ATTR_NULL
  56 };
  57
  58 static inline int virtio_id_match(const struct virtio_device *dev,
  59                                   const struct virtio_device_id *id)
  60 {
  61         if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
  62                 return 0;
  63
  64         return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
  65 }
  66
  67 /* This looks through all the IDs a driver claims to support.  If any of them
  68  * match, we return 1 and the kernel will call virtio_dev_probe(). */
  69 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
  70 {
  71         unsigned int i;
  72         struct virtio_device *dev = container_of(_dv,struct virtio_device,dev);
  73         const struct virtio_device_id *ids;
  74
  75         ids = container_of(_dr, struct virtio_driver, driver)->id_table;
  76         for (i = 0; ids[i].device; i++)
  77                 if (virtio_id_match(dev, &ids[i]))
  78                         return 1;
  79         return 0;
  80 }
  81
  82 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
  83 {
  84         struct virtio_device *dev = container_of(_dv,struct virtio_device,dev);
  85
  86         return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
  87                               dev->id.device, dev->id.vendor);
  88 }
  89
  90 static void add_status(struct virtio_device *dev, unsigned status)
  91 {
  92         dev->config->set_status(dev, dev->config->get_status(dev) | status);
  93 }
  94
  95 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
  96                                          unsigned int fbit)
  97 {
  98         unsigned int i;
  99         struct virtio_driver *drv = container_of(vdev->dev.driver,
 100                                                  struct virtio_driver, 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 = container_of(_d,struct virtio_device,dev);
 113         struct virtio_driver *drv = container_of(dev->dev.driver,
 114                                                  struct virtio_driver, driver);
 115         u32 device_features;
 116
 117         /* We have a driver! */
 118         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 119
 120         /* Figure out what features the device supports. */
 121         device_features = dev->config->get_features(dev);
 122
 123         /* Features supported by both device and driver into dev->features. */
 124         memset(dev->features, 0, sizeof(dev->features));
 125         for (i = 0; i < drv->feature_table_size; i++) {
 126                 unsigned int f = drv->feature_table[i];
 127                 BUG_ON(f >= 32);
 128                 if (device_features & (1 << f))
 129                         set_bit(f, dev->features);
 130         }
 131
 132         /* Transport features always preserved to pass to finalize_features. */
 133         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 134                 if (device_features & (1 << i))
 135                         set_bit(i, dev->features);
 136
 137         dev->config->finalize_features(dev);
 138
 139         err = drv->probe(dev);
 140         if (err)
 141                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 142         else
 143                 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 144
 145         return err;
 146 }
 147
 148 static int virtio_dev_remove(struct device *_d)
 149 {
 150         struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
 151         struct virtio_driver *drv = container_of(dev->dev.driver,
 152                                                  struct virtio_driver, driver);
 153
 154         drv->remove(dev);
 155
 156         /* Driver should have reset device. */
 157         BUG_ON(dev->config->get_status(dev));
 158
 159         /* Acknowledge the device's existence again. */
 160         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 161         return 0;
 162 }
 163
 164 static struct bus_type virtio_bus = {
 165         .name  = "virtio",
 166         .match = virtio_dev_match,
 167         .dev_attrs = virtio_dev_attrs,
 168         .uevent = virtio_uevent,
 169         .probe = virtio_dev_probe,
 170         .remove = virtio_dev_remove,
 171 };
 172
 173 int register_virtio_driver(struct virtio_driver *driver)
 174 {
 175         /* Catch this early. */
 176         BUG_ON(driver->feature_table_size && !driver->feature_table);
 177         driver->driver.bus = &virtio_bus;
 178         return driver_register(&driver->driver);
 179 }
 180 EXPORT_SYMBOL_GPL(register_virtio_driver);
 181
 182 void unregister_virtio_driver(struct virtio_driver *driver)
 183 {
 184         driver_unregister(&driver->driver);
 185 }
 186 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 187
 188 int register_virtio_device(struct virtio_device *dev)
 189 {
 190         int err;
 191
 192         dev->dev.bus = &virtio_bus;
 193
 194         /* Assign a unique device index and hence name. */
 195         dev->index = dev_index++;
 196         dev_set_name(&dev->dev, "virtio%u", dev->index);
 197
 198         /* We always start by resetting the device, in case a previous
 199          * driver messed it up.  This also tests that code path a little. */
 200         dev->config->reset(dev);
 201
 202         /* Acknowledge that we've seen the device. */
 203         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 204
 205         INIT_LIST_HEAD(&dev->vqs);
 206
 207         /* device_register() causes the bus infrastructure to look for a
 208          * matching driver. */
 209         err = device_register(&dev->dev);
 210         if (err)
 211                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 212         return err;
 213 }
 214 EXPORT_SYMBOL_GPL(register_virtio_device);
 215
 216 void unregister_virtio_device(struct virtio_device *dev)
 217 {
 218         device_unregister(&dev->dev);
 219 }
 220 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 221
 222 static int virtio_init(void)
 223 {
 224         if (bus_register(&virtio_bus) != 0)
 225                 panic("virtio bus registration failed");
 226         return 0;
 227 }
 228
 229 static void __exit virtio_exit(void)
 230 {
 231         bus_unregister(&virtio_bus);
 232 }
 233 core_initcall(virtio_init);
 234 module_exit(virtio_exit);
 235
 236 MODULE_LICENSE("GPL");