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 = dev_to_virtio(_d);
  14         return sprintf(buf, "0x%04x\n", dev->id.device);
  15 }
  16 static DEVICE_ATTR_RO(device);
  17
  18 static ssize_t vendor_show(struct device *_d,
  19                            struct device_attribute *attr, char *buf)
  20 {
  21         struct virtio_device *dev = dev_to_virtio(_d);
  22         return sprintf(buf, "0x%04x\n", dev->id.vendor);
  23 }
  24 static DEVICE_ATTR_RO(vendor);
  25
  26 static ssize_t status_show(struct device *_d,
  27                            struct device_attribute *attr, char *buf)
  28 {
  29         struct virtio_device *dev = dev_to_virtio(_d);
  30         return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
  31 }
  32 static DEVICE_ATTR_RO(status);
  33
  34 static ssize_t modalias_show(struct device *_d,
  35                              struct device_attribute *attr, char *buf)
  36 {
  37         struct virtio_device *dev = dev_to_virtio(_d);
  38         return sprintf(buf, "virtio:d%08Xv%08X\n",
  39                        dev->id.device, dev->id.vendor);
  40 }
  41 static DEVICE_ATTR_RO(modalias);
  42
  43 static ssize_t features_show(struct device *_d,
  44                              struct device_attribute *attr, char *buf)
  45 {
  46         struct virtio_device *dev = dev_to_virtio(_d);
  47         unsigned int i;
  48         ssize_t len = 0;
  49
  50         /* We actually represent this as a bitstring, as it could be
  51          * arbitrary length in future. */
  52         for (i = 0; i < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++)
  53                 len += sprintf(buf+len, "%c",
  54                                test_bit(i, dev->features) ? '1' : '0');
  55         len += sprintf(buf+len, "\n");
  56         return len;
  57 }
  58 static DEVICE_ATTR_RO(features);
  59
  60 static struct attribute *virtio_dev_attrs[] = {
  61         &dev_attr_device.attr,
  62         &dev_attr_vendor.attr,
  63         &dev_attr_status.attr,
  64         &dev_attr_modalias.attr,
  65         &dev_attr_features.attr,
  66         NULL,
  67 };
  68 ATTRIBUTE_GROUPS(virtio_dev);
  69
  70 static inline int virtio_id_match(const struct virtio_device *dev,
  71                                   const struct virtio_device_id *id)
  72 {
  73         if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
  74                 return 0;
  75
  76         return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
  77 }
  78
  79 /* This looks through all the IDs a driver claims to support.  If any of them
  80  * match, we return 1 and the kernel will call virtio_dev_probe(). */
  81 static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
  82 {
  83         unsigned int i;
  84         struct virtio_device *dev = dev_to_virtio(_dv);
  85         const struct virtio_device_id *ids;
  86
  87         ids = drv_to_virtio(_dr)->id_table;
  88         for (i = 0; ids[i].device; i++)
  89                 if (virtio_id_match(dev, &ids[i]))
  90                         return 1;
  91         return 0;
  92 }
  93
  94 static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
  95 {
  96         struct virtio_device *dev = dev_to_virtio(_dv);
  97
  98         return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
  99                               dev->id.device, dev->id.vendor);
 100 }
 101
 102 static void add_status(struct virtio_device *dev, unsigned status)
 103 {
 104         dev->config->set_status(dev, dev->config->get_status(dev) | status);
 105 }
 106
 107 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
 108                                          unsigned int fbit)
 109 {
 110         unsigned int i;
 111         struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
 112
 113         for (i = 0; i < drv->feature_table_size; i++)
 114                 if (drv->feature_table[i] == fbit)
 115                         return;
 116         BUG();
 117 }
 118 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
 119
 120 static int virtio_dev_probe(struct device *_d)
 121 {
 122         int err, i;
 123         struct virtio_device *dev = dev_to_virtio(_d);
 124         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 125         u32 device_features;
 126
 127         /* We have a driver! */
 128         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 129
 130         /* Figure out what features the device supports. */
 131         device_features = dev->config->get_features(dev);
 132
 133         /* Features supported by both device and driver into dev->features. */
 134         memset(dev->features, 0, sizeof(dev->features));
 135         for (i = 0; i < drv->feature_table_size; i++) {
 136                 unsigned int f = drv->feature_table[i];
 137                 BUG_ON(f >= 32);
 138                 if (device_features & (1 << f))
 139                         set_bit(f, dev->features);
 140         }
 141
 142         /* Transport features always preserved to pass to finalize_features. */
 143         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 144                 if (device_features & (1 << i))
 145                         set_bit(i, dev->features);
 146
 147         dev->config->finalize_features(dev);
 148
 149         err = drv->probe(dev);
 150         if (err)
 151                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 152         else {
 153                 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 154                 if (drv->scan)
 155                         drv->scan(dev);
 156         }
 157
 158         return err;
 159 }
 160
 161 static int virtio_dev_remove(struct device *_d)
 162 {
 163         struct virtio_device *dev = dev_to_virtio(_d);
 164         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 165
 166         drv->remove(dev);
 167
 168         /* Driver should have reset device. */
 169         WARN_ON_ONCE(dev->config->get_status(dev));
 170
 171         /* Acknowledge the device's existence again. */
 172         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 173         return 0;
 174 }
 175
 176 static struct bus_type virtio_bus = {
 177         .name  = "virtio",
 178         .match = virtio_dev_match,
 179         .dev_groups = virtio_dev_groups,
 180         .uevent = virtio_uevent,
 181         .probe = virtio_dev_probe,
 182         .remove = virtio_dev_remove,
 183 };
 184
 185 int register_virtio_driver(struct virtio_driver *driver)
 186 {
 187         /* Catch this early. */
 188         BUG_ON(driver->feature_table_size && !driver->feature_table);
 189         driver->driver.bus = &virtio_bus;
 190         return driver_register(&driver->driver);
 191 }
 192 EXPORT_SYMBOL_GPL(register_virtio_driver);
 193
 194 void unregister_virtio_driver(struct virtio_driver *driver)
 195 {
 196         driver_unregister(&driver->driver);
 197 }
 198 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 199
 200 int register_virtio_device(struct virtio_device *dev)
 201 {
 202         int err;
 203
 204         dev->dev.bus = &virtio_bus;
 205
 206         /* Assign a unique device index and hence name. */
 207         err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 208         if (err < 0)
 209                 goto out;
 210
 211         dev->index = err;
 212         dev_set_name(&dev->dev, "virtio%u", dev->index);
 213
 214         /* We always start by resetting the device, in case a previous
 215          * driver messed it up.  This also tests that code path a little. */
 216         dev->config->reset(dev);
 217
 218         /* Acknowledge that we've seen the device. */
 219         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 220
 221         INIT_LIST_HEAD(&dev->vqs);
 222
 223         /* device_register() causes the bus infrastructure to look for a
 224          * matching driver. */
 225         err = device_register(&dev->dev);
 226 out:
 227         if (err)
 228                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 229         return err;
 230 }
 231 EXPORT_SYMBOL_GPL(register_virtio_device);
 232
 233 void unregister_virtio_device(struct virtio_device *dev)
 234 {
 235         int index = dev->index; /* save for after device release */
 236
 237         device_unregister(&dev->dev);
 238         ida_simple_remove(&virtio_index_ida, index);
 239 }
 240 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 241
 242 static int virtio_init(void)
 243 {
 244         if (bus_register(&virtio_bus) != 0)
 245                 panic("virtio bus registration failed");
 246         return 0;
 247 }
 248
 249 static void __exit virtio_exit(void)
 250 {
 251         bus_unregister(&virtio_bus);
 252 }
 253 core_initcall(virtio_init);
 254 module_exit(virtio_exit);
 255
 256 MODULE_LICENSE("GPL");