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 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 } 22 static 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 } 28 static 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 } 35 static 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 } 50 static 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 59 static 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(). */ 70 static 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 83 static 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 91 static void add_status(struct virtio_device *dev, unsigned status) 92 { 93 dev->config->set_status(dev, dev->config->get_status(dev) | status); 94 } 95 96 void 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 } 107 EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature); 108 109 static 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 } 149 150 static 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 } 164 165 static 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 }; 173 174 int 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 } 181 EXPORT_SYMBOL_GPL(register_virtio_driver); 182 183 void unregister_virtio_driver(struct virtio_driver *driver) 184 { 185 driver_unregister(&driver->driver); 186 } 187 EXPORT_SYMBOL_GPL(unregister_virtio_driver); 188 189 int 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); 215 out: 216 if (err) 217 add_status(dev, VIRTIO_CONFIG_S_FAILED); 218 return err; 219 } 220 EXPORT_SYMBOL_GPL(register_virtio_device); 221 222 void 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 } 229 EXPORT_SYMBOL_GPL(unregister_virtio_device); 230 231 static int virtio_init(void) 232 { 233 if (bus_register(&virtio_bus) != 0) 234 panic("virtio bus registration failed"); 235 return 0; 236 } 237 238 static void __exit virtio_exit(void) 239 { 240 bus_unregister(&virtio_bus); 241 } 242 core_initcall(virtio_init); 243 module_exit(virtio_exit); 244 245 MODULE_LICENSE("GPL"); 246