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 = container_of(_d,struct virtio_device,dev);
  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 = container_of(_d,struct virtio_device,dev);
  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 = container_of(_d,struct virtio_device,dev);
  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 = 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}
  36static 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}
  51static 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
  60static 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(). */
  71static 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
  84static 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
  92static void add_status(struct virtio_device *dev, unsigned status)
  93{
  94        dev->config->set_status(dev, dev->config->get_status(dev) | status);
  95}
  96
  97void 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}
 109EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
 110
 111static 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
 153static 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
 169static 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
 178int 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}
 185EXPORT_SYMBOL_GPL(register_virtio_driver);
 186
 187void unregister_virtio_driver(struct virtio_driver *driver)
 188{
 189        driver_unregister(&driver->driver);
 190}
 191EXPORT_SYMBOL_GPL(unregister_virtio_driver);
 192
 193int 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);
 219out:
 220        if (err)
 221                add_status(dev, VIRTIO_CONFIG_S_FAILED);
 222        return err;
 223}
 224EXPORT_SYMBOL_GPL(register_virtio_device);
 225
 226void unregister_virtio_device(struct virtio_device *dev)
 227{
 228        int index = dev->index; /* save for after device release */
 229
 230        device_unregister(&dev->dev);
 231        ida_simple_remove(&virtio_index_ida, index);
 232}
 233EXPORT_SYMBOL_GPL(unregister_virtio_device);
 234
 235static int virtio_init(void)
 236{
 237        if (bus_register(&virtio_bus) != 0)
 238                panic("virtio bus registration failed");
 239        return 0;
 240}
 241
 242static void __exit virtio_exit(void)
 243{
 244        bus_unregister(&virtio_bus);
 245}
 246core_initcall(virtio_init);
 247module_exit(virtio_exit);
 248
 249MODULE_LICENSE("GPL");
 250
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