1 /* 2 * drivers/base/dd.c - The core device/driver interactions. 3 * 4 * This file contains the (sometimes tricky) code that controls the 5 * interactions between devices and drivers, which primarily includes 6 * driver binding and unbinding. 7 * 8 * All of this code used to exist in drivers/base/bus.c, but was 9 * relocated to here in the name of compartmentalization (since it wasn't 10 * strictly code just for the 'struct bus_type'. 11 * 12 * Copyright (c) 2002-5 Patrick Mochel 13 * Copyright (c) 2002-3 Open Source Development Labs 14 * 15 * This file is released under the GPLv2 16 */ 17 18 #include <linux/device.h> 19 #include <linux/module.h> 20 #include <linux/kthread.h> 21 #include <linux/wait.h> 22 23 #include "base.h" 24 #include "power/power.h" 25 26 #define to_drv(node) container_of(node, struct device_driver, kobj.entry) 27 28 29 static void driver_bound(struct device *dev) 30 { 31 if (klist_node_attached(&dev->knode_driver)) { 32 printk(KERN_WARNING "%s: device %s already bound\n", 33 __FUNCTION__, kobject_name(&dev->kobj)); 34 return; 35 } 36 37 pr_debug("bound device '%s' to driver '%s'\n", 38 dev->bus_id, dev->driver->name); 39 40 if (dev->bus) 41 blocking_notifier_call_chain(&dev->bus->bus_notifier, 42 BUS_NOTIFY_BOUND_DRIVER, dev); 43 44 klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices); 45 } 46 47 static int driver_sysfs_add(struct device *dev) 48 { 49 int ret; 50 51 ret = sysfs_create_link(&dev->driver->kobj, &dev->kobj, 52 kobject_name(&dev->kobj)); 53 if (ret == 0) { 54 ret = sysfs_create_link(&dev->kobj, &dev->driver->kobj, 55 "driver"); 56 if (ret) 57 sysfs_remove_link(&dev->driver->kobj, 58 kobject_name(&dev->kobj)); 59 } 60 return ret; 61 } 62 63 static void driver_sysfs_remove(struct device *dev) 64 { 65 struct device_driver *drv = dev->driver; 66 67 if (drv) { 68 sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj)); 69 sysfs_remove_link(&dev->kobj, "driver"); 70 } 71 } 72 73 /** 74 * device_bind_driver - bind a driver to one device. 75 * @dev: device. 76 * 77 * Allow manual attachment of a driver to a device. 78 * Caller must have already set @dev->driver. 79 * 80 * Note that this does not modify the bus reference count 81 * nor take the bus's rwsem. Please verify those are accounted 82 * for before calling this. (It is ok to call with no other effort 83 * from a driver's probe() method.) 84 * 85 * This function must be called with @dev->sem held. 86 */ 87 int device_bind_driver(struct device *dev) 88 { 89 int ret; 90 91 ret = driver_sysfs_add(dev); 92 if (!ret) 93 driver_bound(dev); 94 return ret; 95 } 96 97 struct stupid_thread_structure { 98 struct device_driver *drv; 99 struct device *dev; 100 }; 101 102 static atomic_t probe_count = ATOMIC_INIT(0); 103 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue); 104 105 static int really_probe(void *void_data) 106 { 107 struct stupid_thread_structure *data = void_data; 108 struct device_driver *drv = data->drv; 109 struct device *dev = data->dev; 110 int ret = 0; 111 112 atomic_inc(&probe_count); 113 pr_debug("%s: Probing driver %s with device %s\n", 114 drv->bus->name, drv->name, dev->bus_id); 115 116 dev->driver = drv; 117 if (driver_sysfs_add(dev)) { 118 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n", 119 __FUNCTION__, dev->bus_id); 120 goto probe_failed; 121 } 122 123 if (dev->bus->probe) { 124 ret = dev->bus->probe(dev); 125 if (ret) 126 goto probe_failed; 127 } else if (drv->probe) { 128 ret = drv->probe(dev); 129 if (ret) 130 goto probe_failed; 131 } 132 133 driver_bound(dev); 134 ret = 1; 135 pr_debug("%s: Bound Device %s to Driver %s\n", 136 drv->bus->name, dev->bus_id, drv->name); 137 goto done; 138 139 probe_failed: 140 driver_sysfs_remove(dev); 141 dev->driver = NULL; 142 143 if (ret != -ENODEV && ret != -ENXIO) { 144 /* driver matched but the probe failed */ 145 printk(KERN_WARNING 146 "%s: probe of %s failed with error %d\n", 147 drv->name, dev->bus_id, ret); 148 } 149 /* 150 * Ignore errors returned by ->probe so that the next driver can try 151 * its luck. 152 */ 153 ret = 0; 154 done: 155 kfree(data); 156 atomic_dec(&probe_count); 157 wake_up(&probe_waitqueue); 158 return ret; 159 } 160 161 /** 162 * driver_probe_done 163 * Determine if the probe sequence is finished or not. 164 * 165 * Should somehow figure out how to use a semaphore, not an atomic variable... 166 */ 167 int driver_probe_done(void) 168 { 169 pr_debug("%s: probe_count = %d\n", __FUNCTION__, 170 atomic_read(&probe_count)); 171 if (atomic_read(&probe_count)) 172 return -EBUSY; 173 return 0; 174 } 175 176 /** 177 * driver_probe_device - attempt to bind device & driver together 178 * @drv: driver to bind a device to 179 * @dev: device to try to bind to the driver 180 * 181 * First, we call the bus's match function, if one present, which should 182 * compare the device IDs the driver supports with the device IDs of the 183 * device. Note we don't do this ourselves because we don't know the 184 * format of the ID structures, nor what is to be considered a match and 185 * what is not. 186 * 187 * This function returns 1 if a match is found, an error if one occurs 188 * (that is not -ENODEV or -ENXIO), and 0 otherwise. 189 * 190 * This function must be called with @dev->sem held. When called for a 191 * USB interface, @dev->parent->sem must be held as well. 192 */ 193 int driver_probe_device(struct device_driver * drv, struct device * dev) 194 { 195 struct stupid_thread_structure *data; 196 struct task_struct *probe_task; 197 int ret = 0; 198 199 if (!device_is_registered(dev)) 200 return -ENODEV; 201 if (drv->bus->match && !drv->bus->match(dev, drv)) 202 goto done; 203 204 pr_debug("%s: Matched Device %s with Driver %s\n", 205 drv->bus->name, dev->bus_id, drv->name); 206 207 data = kmalloc(sizeof(*data), GFP_KERNEL); 208 if (!data) 209 return -ENOMEM; 210 data->drv = drv; 211 data->dev = dev; 212 213 if (drv->multithread_probe) { 214 probe_task = kthread_run(really_probe, data, 215 "probe-%s", dev->bus_id); 216 if (IS_ERR(probe_task)) 217 ret = really_probe(data); 218 } else 219 ret = really_probe(data); 220 221 done: 222 return ret; 223 } 224 225 static int __device_attach(struct device_driver * drv, void * data) 226 { 227 struct device * dev = data; 228 return driver_probe_device(drv, dev); 229 } 230 231 /** 232 * device_attach - try to attach device to a driver. 233 * @dev: device. 234 * 235 * Walk the list of drivers that the bus has and call 236 * driver_probe_device() for each pair. If a compatible 237 * pair is found, break out and return. 238 * 239 * Returns 1 if the device was bound to a driver; 240 * 0 if no matching device was found; error code otherwise. 241 * 242 * When called for a USB interface, @dev->parent->sem must be held. 243 */ 244 int device_attach(struct device * dev) 245 { 246 int ret = 0; 247 248 down(&dev->sem); 249 if (dev->driver) { 250 ret = device_bind_driver(dev); 251 if (ret == 0) 252 ret = 1; 253 } else 254 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach); 255 up(&dev->sem); 256 return ret; 257 } 258 259 static int __driver_attach(struct device * dev, void * data) 260 { 261 struct device_driver * drv = data; 262 263 /* 264 * Lock device and try to bind to it. We drop the error 265 * here and always return 0, because we need to keep trying 266 * to bind to devices and some drivers will return an error 267 * simply if it didn't support the device. 268 * 269 * driver_probe_device() will spit a warning if there 270 * is an error. 271 */ 272 273 if (dev->parent) /* Needed for USB */ 274 down(&dev->parent->sem); 275 down(&dev->sem); 276 if (!dev->driver) 277 driver_probe_device(drv, dev); 278 up(&dev->sem); 279 if (dev->parent) 280 up(&dev->parent->sem); 281 282 return 0; 283 } 284 285 /** 286 * driver_attach - try to bind driver to devices. 287 * @drv: driver. 288 * 289 * Walk the list of devices that the bus has on it and try to 290 * match the driver with each one. If driver_probe_device() 291 * returns 0 and the @dev->driver is set, we've found a 292 * compatible pair. 293 */ 294 int driver_attach(struct device_driver * drv) 295 { 296 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); 297 } 298 299 /** 300 * device_release_driver - manually detach device from driver. 301 * @dev: device. 302 * 303 * Manually detach device from driver. 304 * 305 * __device_release_driver() must be called with @dev->sem held. 306 * When called for a USB interface, @dev->parent->sem must be held 307 * as well. 308 */ 309 310 static void __device_release_driver(struct device * dev) 311 { 312 struct device_driver * drv; 313 314 drv = dev->driver; 315 if (drv) { 316 get_driver(drv); 317 driver_sysfs_remove(dev); 318 sysfs_remove_link(&dev->kobj, "driver"); 319 klist_remove(&dev->knode_driver); 320 321 if (dev->bus) 322 blocking_notifier_call_chain(&dev->bus->bus_notifier, 323 BUS_NOTIFY_UNBIND_DRIVER, 324 dev); 325 326 if (dev->bus && dev->bus->remove) 327 dev->bus->remove(dev); 328 else if (drv->remove) 329 drv->remove(dev); 330 dev->driver = NULL; 331 put_driver(drv); 332 } 333 } 334 335 void device_release_driver(struct device * dev) 336 { 337 /* 338 * If anyone calls device_release_driver() recursively from 339 * within their ->remove callback for the same device, they 340 * will deadlock right here. 341 */ 342 down(&dev->sem); 343 __device_release_driver(dev); 344 up(&dev->sem); 345 } 346 347 348 /** 349 * driver_detach - detach driver from all devices it controls. 350 * @drv: driver. 351 */ 352 void driver_detach(struct device_driver * drv) 353 { 354 struct device * dev; 355 356 for (;;) { 357 spin_lock(&drv->klist_devices.k_lock); 358 if (list_empty(&drv->klist_devices.k_list)) { 359 spin_unlock(&drv->klist_devices.k_lock); 360 break; 361 } 362 dev = list_entry(drv->klist_devices.k_list.prev, 363 struct device, knode_driver.n_node); 364 get_device(dev); 365 spin_unlock(&drv->klist_devices.k_lock); 366 367 if (dev->parent) /* Needed for USB */ 368 down(&dev->parent->sem); 369 down(&dev->sem); 370 if (dev->driver == drv) 371 __device_release_driver(dev); 372 up(&dev->sem); 373 if (dev->parent) 374 up(&dev->parent->sem); 375 put_device(dev); 376 } 377 } 378 379 #ifdef CONFIG_PCI_MULTITHREAD_PROBE 380 static int __init wait_for_probes(void) 381 { 382 DEFINE_WAIT(wait); 383 384 printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__, 385 atomic_read(&probe_count)); 386 if (!atomic_read(&probe_count)) 387 return 0; 388 while (atomic_read(&probe_count)) { 389 prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE); 390 if (atomic_read(&probe_count)) 391 schedule(); 392 } 393 finish_wait(&probe_waitqueue, &wait); 394 return 0; 395 } 396 397 core_initcall_sync(wait_for_probes); 398 postcore_initcall_sync(wait_for_probes); 399 arch_initcall_sync(wait_for_probes); 400 subsys_initcall_sync(wait_for_probes); 401 fs_initcall_sync(wait_for_probes); 402 device_initcall_sync(wait_for_probes); 403 late_initcall_sync(wait_for_probes); 404 #endif 405 406 EXPORT_SYMBOL_GPL(device_bind_driver); 407 EXPORT_SYMBOL_GPL(device_release_driver); 408 EXPORT_SYMBOL_GPL(device_attach); 409 EXPORT_SYMBOL_GPL(driver_attach); 410 411