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 < sizeof(dev->features)*8; i++)
  53                 len += sprintf(buf+len, "%c",
  54                                __virtio_test_bit(dev, i) ? '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 void __virtio_config_changed(struct virtio_device *dev)
 121 {
 122         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 123
 124         if (!dev->config_enabled)
 125                 dev->config_change_pending = true;
 126         else if (drv && drv->config_changed)
 127                 drv->config_changed(dev);
 128 }
 129
 130 void virtio_config_changed(struct virtio_device *dev)
 131 {
 132         unsigned long flags;
 133
 134         spin_lock_irqsave(&dev->config_lock, flags);
 135         __virtio_config_changed(dev);
 136         spin_unlock_irqrestore(&dev->config_lock, flags);
 137 }
 138 EXPORT_SYMBOL_GPL(virtio_config_changed);
 139
 140 static void virtio_config_disable(struct virtio_device *dev)
 141 {
 142         spin_lock_irq(&dev->config_lock);
 143         dev->config_enabled = false;
 144         spin_unlock_irq(&dev->config_lock);
 145 }
 146
 147 static void virtio_config_enable(struct virtio_device *dev)
 148 {
 149         spin_lock_irq(&dev->config_lock);
 150         dev->config_enabled = true;
 151         if (dev->config_change_pending)
 152                 __virtio_config_changed(dev);
 153         dev->config_change_pending = false;
 154         spin_unlock_irq(&dev->config_lock);
 155 }
 156
 157 static int virtio_dev_probe(struct device *_d)
 158 {
 159         int err, i;
 160         struct virtio_device *dev = dev_to_virtio(_d);
 161         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 162         u64 device_features;
 163
 164         /* We have a driver! */
 165         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 166
 167         /* Figure out what features the device supports. */
 168         device_features = dev->config->get_features(dev);
 169
 170         /* Features supported by both device and driver into dev->features. */
 171         dev->features = 0;
 172         for (i = 0; i < drv->feature_table_size; i++) {
 173                 unsigned int f = drv->feature_table[i];
 174                 BUG_ON(f >= 64);
 175                 if (device_features & (1ULL << f))
 176                         __virtio_set_bit(dev, f);
 177         }
 178
 179         /* Transport features always preserved to pass to finalize_features. */
 180         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 181                 if (device_features & (1ULL << i))
 182                         __virtio_set_bit(dev, i);
 183
 184         dev->config->finalize_features(dev);
 185
 186         err = drv->probe(dev);
 187         if (err)
 188                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 189         else {
 190                 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 191                 if (drv->scan)
 192                         drv->scan(dev);
 193
 194                 virtio_config_enable(dev);
 195         }
 196
 197         return err;
 198 }
 199
 200 static int virtio_dev_remove(struct device *_d)
 201 {
 202         struct virtio_device *dev = dev_to_virtio(_d);
 203         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 204
 205         virtio_config_disable(dev);
 206
 207         drv->remove(dev);
 208
 209         /* Driver should have reset device. */
 210         WARN_ON_ONCE(dev->config->get_status(dev));
 211
 212         /* Acknowledge the device's existence again. */
 213         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 214         return 0;
 215 }
 216
 217 static struct bus_type virtio_bus = {
 218         .name  = "virtio",
 219         .match = virtio_dev_match,
 220         .dev_groups = virtio_dev_groups,
 221         .uevent = virtio_uevent,
 222         .probe = virtio_dev_probe,
 223         .remove = virtio_dev_remove,
 224 };
 225
 226 int register_virtio_driver(struct virtio_driver *driver)
 227 {
 228         /* Catch this early. */
 229         BUG_ON(driver->feature_table_size && !driver->feature_table);
 230         driver->driver.bus = &virtio_bus;
 231         return driver_register(&driver->driver);
 232 }
 233 EXPORT_SYMBOL_GPL(register_virtio_driver);
 234
 235 void unregister_virtio_driver(struct virtio_driver *driver)
 236 {
 237         driver_unregister(&driver->driver);
 238 }
 239 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 240
 241 int register_virtio_device(struct virtio_device *dev)
 242 {
 243         int err;
 244
 245         dev->dev.bus = &virtio_bus;
 246
 247         /* Assign a unique device index and hence name. */
 248         err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 249         if (err < 0)
 250                 goto out;
 251
 252         dev->index = err;
 253         dev_set_name(&dev->dev, "virtio%u", dev->index);
 254
 255         spin_lock_init(&dev->config_lock);
 256         dev->config_enabled = false;
 257         dev->config_change_pending = false;
 258
 259         /* We always start by resetting the device, in case a previous
 260          * driver messed it up.  This also tests that code path a little. */
 261         dev->config->reset(dev);
 262
 263         /* Acknowledge that we've seen the device. */
 264         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 265
 266         INIT_LIST_HEAD(&dev->vqs);
 267
 268         /* device_register() causes the bus infrastructure to look for a
 269          * matching driver. */
 270         err = device_register(&dev->dev);
 271 out:
 272         if (err)
 273                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 274         return err;
 275 }
 276 EXPORT_SYMBOL_GPL(register_virtio_device);
 277
 278 void unregister_virtio_device(struct virtio_device *dev)
 279 {
 280         int index = dev->index; /* save for after device release */
 281
 282         device_unregister(&dev->dev);
 283         ida_simple_remove(&virtio_index_ida, index);
 284 }
 285 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 286
 287 #ifdef CONFIG_PM_SLEEP
 288 int virtio_device_freeze(struct virtio_device *dev)
 289 {
 290         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 291
 292         virtio_config_disable(dev);
 293
 294         dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
 295
 296         if (drv && drv->freeze)
 297                 return drv->freeze(dev);
 298
 299         return 0;
 300 }
 301 EXPORT_SYMBOL_GPL(virtio_device_freeze);
 302
 303 int virtio_device_restore(struct virtio_device *dev)
 304 {
 305         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 306
 307         /* We always start by resetting the device, in case a previous
 308          * driver messed it up. */
 309         dev->config->reset(dev);
 310
 311         /* Acknowledge that we've seen the device. */
 312         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 313
 314         /* Maybe driver failed before freeze.
 315          * Restore the failed status, for debugging. */
 316         if (dev->failed)
 317                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 318
 319         if (!drv)
 320                 return 0;
 321
 322         /* We have a driver! */
 323         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 324
 325         dev->config->finalize_features(dev);
 326
 327         if (drv->restore) {
 328                 int ret = drv->restore(dev);
 329                 if (ret) {
 330                         add_status(dev, VIRTIO_CONFIG_S_FAILED);
 331                         return ret;
 332                 }
 333         }
 334
 335         /* Finally, tell the device we're all set */
 336         add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 337
 338         virtio_config_enable(dev);
 339
 340         return 0;
 341 }
 342 EXPORT_SYMBOL_GPL(virtio_device_restore);
 343 #endif
 344
 345 static int virtio_init(void)
 346 {
 347         if (bus_register(&virtio_bus) != 0)
 348                 panic("virtio bus registration failed");
 349         return 0;
 350 }
 351
 352 static void __exit virtio_exit(void)
 353 {
 354         bus_unregister(&virtio_bus);
 355 }
 356 core_initcall(virtio_init);
 357 module_exit(virtio_exit);
 358
 359 MODULE_LICENSE("GPL");