linux/drivers/virtio/virtio.c
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   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. */
   8static DEFINE_IDA(virtio_index_ida);
   9
  10static 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}
  16static ssize_t vendor_show(struct device *_d,
  17                           struct device_attribute *attr, char *buf)
  18{
  19        struct virtio_device *dev = dev_to_virtio(_d);
  20        return sprintf(buf, "0x%04x\n", dev->id.vendor);
  21}
  22static ssize_t status_show(struct device *_d,
  23                           struct device_attribute *attr, char *buf)
  24{
  25        struct virtio_device *dev = dev_to_virtio(_d);
  26        return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
  27}
  28static ssize_t modalias_show(struct device *_d,
  29                             struct device_attribute *attr, char *buf)
  30{
  31        struct virtio_device *dev = dev_to_virtio(_d);
  32        return sprintf(buf, "virtio:d%08Xv%08X\n",
  33                       dev->id.device, dev->id.vendor);
  34}
  35static ssize_t features_show(struct device *_d,
  36                             struct device_attribute *attr, char *buf)
  37{
  38        struct virtio_device *dev = dev_to_virtio(_d);
  39        unsigned int i;
  40        ssize_t len = 0;
  41
  42        /* We actually represent this as a bitstring, as it could be
  43         * arbitrary length in future. */
  44        for (i = 0; i < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++)
  45                len += sprintf(buf+len, "%c",
  46                               test_bit(i, dev->features) ? '1' : '0');
  47        len += sprintf(buf+len, "\n");
  48        return len;
  49}
  50static struct device_attribute virtio_dev_attrs[] = {
  51        __ATTR_RO(device),
  52        __ATTR_RO(vendor),
  53        __ATTR_RO(status),
  54        __ATTR_RO(modalias),
  55        __ATTR_RO(features),
  56        __ATTR_NULL
  57};
  58
  59static inline int virtio_id_match(const struct virtio_device *dev,
  60                                  const struct virtio_device_id *id)
  61{
  62        if (id->device != dev->id.device && id->device != VIRTIO_DEV_ANY_ID)
  63                return 0;
  64
  65        return id->vendor == VIRTIO_DEV_ANY_ID || id->vendor == dev->id.vendor;
  66}
  67
  68/* This looks through all the IDs a driver claims to support.  If any of them
  69 * match, we return 1 and the kernel will call virtio_dev_probe(). */
  70static int virtio_dev_match(struct device *_dv, struct device_driver *_dr)
  71{
  72        unsigned int i;
  73        struct virtio_device *dev = dev_to_virtio(_dv);
  74        const struct virtio_device_id *ids;
  75
  76        ids = drv_to_virtio(_dr)->id_table;
  77        for (i = 0; ids[i].device; i++)
  78                if (virtio_id_match(dev, &ids[i]))
  79                        return 1;
  80        return 0;
  81}
  82
  83static int virtio_uevent(struct device *_dv, struct kobj_uevent_env *env)
  84{
  85        struct virtio_device *dev = dev_to_virtio(_dv);
  86
  87        return add_uevent_var(env, "MODALIAS=virtio:d%08Xv%08X",
  88                              dev->id.device, dev->id.vendor);
  89}
  90
  91static void add_status(struct virtio_device *dev, unsigned status)
  92{
  93        dev->config->set_status(dev, dev->config->get_status(dev) | status);
  94}
  95
  96void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
  97                                         unsigned int fbit)
  98{
  99        unsigned int i;
 100        struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver);
 101
 102        for (i = 0; i < drv->feature_table_size; i++)
 103                if (drv->feature_table[i] == fbit)
 104                        return;
 105        BUG();
 106}
 107EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
 108
 109static int virtio_dev_probe(struct device *_d)
 110{
 111        int err, i;
 112        struct virtio_device *dev = dev_to_virtio(_d);
 113        struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 114        u32 device_features;
 115
 116        /* We have a driver! */
 117        add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 118
 119        /* Figure out what features the device supports. */
 120        device_features = dev->config->get_features(dev);
 121
 122        /* Features supported by both device and driver into dev->features. */
 123        memset(dev->features, 0, sizeof(dev->features));
 124        for (i = 0; i < drv->feature_table_size; i++) {
 125                unsigned int f = drv->feature_table[i];
 126                BUG_ON(f >= 32);
 127                if (device_features & (1 << f))
 128                        set_bit(f, dev->features);
 129        }
 130
 131        /* Transport features always preserved to pass to finalize_features. */
 132        for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
 133                if (device_features & (1 << i))
 134                        set_bit(i, dev->features);
 135
 136        dev->config->finalize_features(dev);
 137
 138        err = drv->probe(dev);
 139        if (err)
 140                add_status(dev, VIRTIO_CONFIG_S_FAILED);
 141        else {
 142                add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
 143                if (drv->scan)
 144                        drv->scan(dev);
 145        }
 146
 147        return err;
 148}
 149
 150static int virtio_dev_remove(struct device *_d)
 151{
 152        struct virtio_device *dev = dev_to_virtio(_d);
 153        struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
 154
 155        drv->remove(dev);
 156
 157        /* Driver should have reset device. */
 158        WARN_ON_ONCE(dev->config->get_status(dev));
 159
 160        /* Acknowledge the device's existence again. */
 161        add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 162        return 0;
 163}
 164
 165static struct bus_type virtio_bus = {
 166        .name  = "virtio",
 167        .match = virtio_dev_match,
 168        .dev_attrs = virtio_dev_attrs,
 169        .uevent = virtio_uevent,
 170        .probe = virtio_dev_probe,
 171        .remove = virtio_dev_remove,
 172};
 173
 174int register_virtio_driver(struct virtio_driver *driver)
 175{
 176        /* Catch this early. */
 177        BUG_ON(driver->feature_table_size && !driver->feature_table);
 178        driver->driver.bus = &virtio_bus;
 179        return driver_register(&driver->driver);
 180}
 181EXPORT_SYMBOL_GPL(register_virtio_driver);
 182
 183void unregister_virtio_driver(struct virtio_driver *driver)
 184{
 185        driver_unregister(&driver->driver);
 186}
 187EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 188
 189int register_virtio_device(struct virtio_device *dev)
 190{
 191        int err;
 192
 193        dev->dev.bus = &virtio_bus;
 194
 195        /* Assign a unique device index and hence name. */
 196        err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
 197        if (err < 0)
 198                goto out;
 199
 200        dev->index = err;
 201        dev_set_name(&dev->dev, "virtio%u", dev->index);
 202
 203        /* We always start by resetting the device, in case a previous
 204         * driver messed it up.  This also tests that code path a little. */
 205        dev->config->reset(dev);
 206
 207        /* Acknowledge that we've seen the device. */
 208        add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 209
 210        INIT_LIST_HEAD(&dev->vqs);
 211
 212        /* device_register() causes the bus infrastructure to look for a
 213         * matching driver. */
 214        err = device_register(&dev->dev);
 215out:
 216        if (err)
 217                add_status(dev, VIRTIO_CONFIG_S_FAILED);
 218        return err;
 219}
 220EXPORT_SYMBOL_GPL(register_virtio_device);
 221
 222void unregister_virtio_device(struct virtio_device *dev)
 223{
 224        int index = dev->index; /* save for after device release */
 225
 226        device_unregister(&dev->dev);
 227        ida_simple_remove(&virtio_index_ida, index);
 228}
 229EXPORT_SYMBOL_GPL(unregister_virtio_device);
 230
 231static int virtio_init(void)
 232{
 233        if (bus_register(&virtio_bus) != 0)
 234                panic("virtio bus registration failed");
 235        return 0;
 236}
 237
 238static void __exit virtio_exit(void)
 239{
 240        bus_unregister(&virtio_bus);
 241}
 242core_initcall(virtio_init);
 243module_exit(virtio_exit);
 244
 245MODULE_LICENSE("GPL");
 246
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