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         unsigned status;
 164
 165         /* We have a driver! */
 166         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 167
 168         /* Figure out what features the device supports. */
 169         device_features = dev->config->get_features(dev);
 170
 171         /* Features supported by both device and driver into dev->features. */
 172         dev->features = 0;
 173         for (i = 0; i < drv->feature_table_size; i++) {
 174                 unsigned int f = drv->feature_table[i];
 175                 BUG_ON(f >= 64);
 176                 if (device_features & (1ULL << f))
 177                         __virtio_set_bit(dev, f);
 178         }
 179
 180         /* Transport features always preserved to pass to finalize_features. */
 181         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 182                 if (device_features & (1ULL << i))
 183                         __virtio_set_bit(dev, i);
 184
 185         dev->config->finalize_features(dev);
 186
 187         if (virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
 188                 add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
 189                 status = dev->config->get_status(dev);
 190                 if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
 191                         dev_err(_d, "virtio: device refuses features: %x\n",
 192                                status);
 193                         err = -ENODEV;
 194                         goto err;
 195                 }
 196         }
 197
 198         err = drv->probe(dev);
 199         if (err)
 200                 goto err;
 201
 202         add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 203         if (drv->scan)
 204                 drv->scan(dev);
 205
 206         virtio_config_enable(dev);
 207
 208         return 0;
 209 err:
 210         add_status(dev, VIRTIO_CONFIG_S_FAILED);
 211         return err;
 212
 213 }
 214
 215 static int virtio_dev_remove(struct device *_d)
 216 {
 217         struct virtio_device *dev = dev_to_virtio(_d);
 218         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 219
 220         virtio_config_disable(dev);
 221
 222         drv->remove(dev);
 223
 224         /* Driver should have reset device. */
 225         WARN_ON_ONCE(dev->config->get_status(dev));
 226
 227         /* Acknowledge the device's existence again. */
 228         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 229         return 0;
 230 }
 231
 232 static struct bus_type virtio_bus = {
 233         .name  = "virtio",
 234         .match = virtio_dev_match,
 235         .dev_groups = virtio_dev_groups,
 236         .uevent = virtio_uevent,
 237         .probe = virtio_dev_probe,
 238         .remove = virtio_dev_remove,
 239 };
 240
 241 int register_virtio_driver(struct virtio_driver *driver)
 242 {
 243         /* Catch this early. */
 244         BUG_ON(driver->feature_table_size && !driver->feature_table);
 245         driver->driver.bus = &virtio_bus;
 246         return driver_register(&driver->driver);
 247 }
 248 EXPORT_SYMBOL_GPL(register_virtio_driver);
 249
 250 void unregister_virtio_driver(struct virtio_driver *driver)
 251 {
 252         driver_unregister(&driver->driver);
 253 }
 254 EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 255
 256 int register_virtio_device(struct virtio_device *dev)
 257 {
 258         int err;
 259
 260         dev->dev.bus = &virtio_bus;
 261
 262         /* Assign a unique device index and hence name. */
 263         err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 264         if (err < 0)
 265                 goto out;
 266
 267         dev->index = err;
 268         dev_set_name(&dev->dev, "virtio%u", dev->index);
 269
 270         spin_lock_init(&dev->config_lock);
 271         dev->config_enabled = false;
 272         dev->config_change_pending = false;
 273
 274         /* We always start by resetting the device, in case a previous
 275          * driver messed it up.  This also tests that code path a little. */
 276         dev->config->reset(dev);
 277
 278         /* Acknowledge that we've seen the device. */
 279         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 280
 281         INIT_LIST_HEAD(&dev->vqs);
 282
 283         /* device_register() causes the bus infrastructure to look for a
 284          * matching driver. */
 285         err = device_register(&dev->dev);
 286 out:
 287         if (err)
 288                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 289         return err;
 290 }
 291 EXPORT_SYMBOL_GPL(register_virtio_device);
 292
 293 void unregister_virtio_device(struct virtio_device *dev)
 294 {
 295         int index = dev->index; /* save for after device release */
 296
 297         device_unregister(&dev->dev);
 298         ida_simple_remove(&virtio_index_ida, index);
 299 }
 300 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 301
 302 #ifdef CONFIG_PM_SLEEP
 303 int virtio_device_freeze(struct virtio_device *dev)
 304 {
 305         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 306
 307         virtio_config_disable(dev);
 308
 309         dev->failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED;
 310
 311         if (drv && drv->freeze)
 312                 return drv->freeze(dev);
 313
 314         return 0;
 315 }
 316 EXPORT_SYMBOL_GPL(virtio_device_freeze);
 317
 318 int virtio_device_restore(struct virtio_device *dev)
 319 {
 320         struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 321
 322         /* We always start by resetting the device, in case a previous
 323          * driver messed it up. */
 324         dev->config->reset(dev);
 325
 326         /* Acknowledge that we've seen the device. */
 327         add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 328
 329         /* Maybe driver failed before freeze.
 330          * Restore the failed status, for debugging. */
 331         if (dev->failed)
 332                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
 333
 334         if (!drv)
 335                 return 0;
 336
 337         /* We have a driver! */
 338         add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 339
 340         dev->config->finalize_features(dev);
 341
 342         if (drv->restore) {
 343                 int ret = drv->restore(dev);
 344                 if (ret) {
 345                         add_status(dev, VIRTIO_CONFIG_S_FAILED);
 346                         return ret;
 347                 }
 348         }
 349
 350         /* Finally, tell the device we're all set */
 351         add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 352
 353         virtio_config_enable(dev);
 354
 355         return 0;
 356 }
 357 EXPORT_SYMBOL_GPL(virtio_device_restore);
 358 #endif
 359
 360 static int virtio_init(void)
 361 {
 362         if (bus_register(&virtio_bus) != 0)
 363                 panic("virtio bus registration failed");
 364         return 0;
 365 }
 366
 367 static void __exit virtio_exit(void)
 368 {
 369         bus_unregister(&virtio_bus);
 370 }
 371 core_initcall(virtio_init);
 372 module_exit(virtio_exit);
 373
 374 MODULE_LICENSE("GPL");