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 = container_of(_d,struct virtio_device,dev);
  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 = container_of(_d,struct virtio_device,dev);
  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 = container_of(_d,struct virtio_device,dev);
  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 = container_of(_d,struct virtio_device,dev);
  32
  33         return sprintf(buf, "virtio:d%08Xv%08X\n",
  34                        dev->id.device, dev->id.vendor);
  35 }
  36 static ssize_t features_show(struct device *_d,
  37                              struct device_attribute *attr, char *buf)
  38 {
  39         struct virtio_device *dev = container_of(_d, struct virtio_device, dev);
  40         unsigned int i;
  41         ssize_t len = 0;
  42
  43         /* We actually represent this as a bitstring, as it could be
  44          * arbitrary length in future. */
  45         for (i = 0; i < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++)
  46                 len += sprintf(buf+len, "%c",
  47                                test_bit(i, dev->features) ? '1' : '0');
  48         len += sprintf(buf+len, "\n");
  49         return len;
  50 }
  51 static struct device_attribute virtio_dev_attrs[] = {
  52         __ATTR_RO(device),
  53         __ATTR_RO(vendor),
  54         __ATTR_RO(status),
  55         __ATTR_RO(modalias),
  56         __ATTR_RO(features),
  57         __ATTR_NULL
  58 };
  59
  60 static inline int virtio_id_match(const struct virtio_device *dev,
  61                                   const struct virtio_device_id *id)
  62 {
  63         if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
  64                 return 0;
  65
  66         return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
  67 }
  68
  69 /* This looks through all the IDs a driver claims to support.  If any of them
  70  * match, we return 1 and the kernel will call virtio_dev_probe(). */
  71 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
  72 {
  73         unsigned int i;
  74         struct virtio_device *dev = container_of(_dv,struct virtio_device,dev);
  75         const struct virtio_device_id *ids;
  76
  77         ids = container_of(_dr, struct virtio_driver, driver)->id_table;
  78         for (i = 0; ids[i].device; i++)
  79                 if (virtio_id_match(dev, &ids[i]))
  80                         return 1;
  81         return 0;
  82 }
  83
  84 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
  85 {
  86         struct virtio_device *dev = container_of(_dv,struct virtio_device,dev);
  87
  88         return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
  89                               dev->id.device, dev->id.vendor);
  90 }
  91
  92 static void add_status(struct virtio_device *dev, unsigned status)
  93 {
  94         dev->config->set_status(dev, dev->config->get_status(dev) | status);
  95 }
  96
  97 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
  98                                          unsigned int fbit)
  99 {
 100         unsigned int i;
 101         struct virtio_driver *drv = container_of(vdev->dev.driver,
 102                                                  struct virtio_driver, driver);
 103
 104         for (i = 0; i < drv->feature_table_size; i++)
 105                 if (drv->feature_table[i] == fbit)
 106                         return;
 107         BUG();
 108 }
 109 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
 110
 111 static int virtio_dev_probe(struct device *_d)
 112 {
 113         int err, i;
 114         struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
 115         struct virtio_driver *drv = container_of(dev->dev.driver,
 116                                                  struct virtio_driver, driver);
 117         u32 device_features;
 118
 119         /* We have a driver! */
 120         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 121
 122         /* Figure out what features the device supports. */
 123         device_features = dev->config->get_features(dev);
 124
 125         /* Features supported by both device and driver into dev->features. */
 126         memset(dev->features, 0, sizeof(dev->features));
 127         for (i = 0; i < drv->feature_table_size; i++) {
 128                 unsigned int f = drv->feature_table[i];
 129                 BUG_ON(f >= 32);
 130                 if (device_features & (1 << f))
 131                         set_bit(f, dev->features);
 132         }
 133
 134         /* Transport features always preserved to pass to finalize_features. */
 135         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 136                 if (device_features & (1 << i))
 137                         set_bit(i, dev->features);
 138
 139         dev->config->finalize_features(dev);
 140
 141         err = drv->probe(dev);
 142         if (err)
 143                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 144         else {
 145                 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 146                 if (drv->scan)
 147                         drv->scan(dev);
 148         }
 149
 150         return err;
 151 }
 152
 153 static int virtio_dev_remove(struct device *_d)
 154 {
 155         struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
 156         struct virtio_driver *drv = container_of(dev->dev.driver,
 157                                                  struct virtio_driver, driver);
 158
 159         drv->remove(dev);
 160
 161         /* Driver should have reset device. */
 162         WARN_ON_ONCE(dev->config->get_status(dev));
 163
 164         /* Acknowledge the device's existence again. */
 165         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 166         return 0;
 167 }
 168
 169 static struct bus_type virtio_bus = {
 170         .name  = "virtio",
 171         .match = virtio_dev_match,
 172         .dev_attrs = virtio_dev_attrs,
 173         .uevent = virtio_uevent,
 174         .probe = virtio_dev_probe,
 175         .remove = virtio_dev_remove,
 176 };
 177
 178 int register_virtio_driver(struct virtio_driver *driver)
 179 {
 180         /* Catch this early. */
 181         BUG_ON(driver->feature_table_size && !driver->feature_table);
 182         driver->driver.bus = &virtio_bus;
 183         return driver_register(&driver->driver);
 184 }
 185 EXPORT_SYMBOL_GPL(register_virtio_driver);
 186
 187 void unregister_virtio_driver(struct virtio_driver *driver)
 188 {
 189         driver_unregister(&driver->driver);
 190 }
 191 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 192
 193 int register_virtio_device(struct virtio_device *dev)
 194 {
 195         int err;
 196
 197         dev->dev.bus = &virtio_bus;
 198
 199         /* Assign a unique device index and hence name. */
 200         err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 201         if (err < 0)
 202                 goto out;
 203
 204         dev->index = err;
 205         dev_set_name(&dev->dev, "virtio%u", dev->index);
 206
 207         /* We always start by resetting the device, in case a previous
 208          * driver messed it up.  This also tests that code path a little. */
 209         dev->config->reset(dev);
 210
 211         /* Acknowledge that we've seen the device. */
 212         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 213
 214         INIT_LIST_HEAD(&dev->vqs);
 215
 216         /* device_register() causes the bus infrastructure to look for a
 217          * matching driver. */
 218         err = device_register(&dev->dev);
 219 out:
 220         if (err)
 221                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 222         return err;
 223 }
 224 EXPORT_SYMBOL_GPL(register_virtio_device);
 225
 226 void unregister_virtio_device(struct virtio_device *dev)
 227 {
 228         device_unregister(&dev->dev);
 229         ida_simple_remove(&virtio_index_ida, dev->index);
 230 }
 231 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 232
 233 static int virtio_init(void)
 234 {
 235         if (bus_register(&virtio_bus) != 0)
 236                 panic("virtio bus registration failed");
 237         return 0;
 238 }
 239
 240 static void __exit virtio_exit(void)
 241 {
 242         bus_unregister(&virtio_bus);
 243 }
 244 core_initcall(virtio_init);
 245 module_exit(virtio_exit);
 246
 247 MODULE_LICENSE("GPL");