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"); 257