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 * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de> 15 * Copyright (c) 2007-2009 Novell Inc. 16 * 17 * This file is released under the GPLv2 18 */ 19 20 #include <linux/device.h> 21 #include <linux/delay.h> 22 #include <linux/module.h> 23 #include <linux/kthread.h> 24 #include <linux/wait.h> 25 #include <linux/async.h> 26 #include <linux/pm_runtime.h> 27 28 #include "base.h" 29 #include "power/power.h" 30 31 32 static void driver_bound(struct device *dev) 33 { 34 if (klist_node_attached(&dev->p->knode_driver)) { 35 printk(KERN_WARNING "%s: device %s already bound\n", 36 __func__, kobject_name(&dev->kobj)); 37 return; 38 } 39 40 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev_name(dev), 41 __func__, dev->driver->name); 42 43 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices); 44 45 if (dev->bus) 46 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 47 BUS_NOTIFY_BOUND_DRIVER, dev); 48 } 49 50 static int driver_sysfs_add(struct device *dev) 51 { 52 int ret; 53 54 if (dev->bus) 55 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 56 BUS_NOTIFY_BIND_DRIVER, dev); 57 58 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj, 59 kobject_name(&dev->kobj)); 60 if (ret == 0) { 61 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj, 62 "driver"); 63 if (ret) 64 sysfs_remove_link(&dev->driver->p->kobj, 65 kobject_name(&dev->kobj)); 66 } 67 return ret; 68 } 69 70 static void driver_sysfs_remove(struct device *dev) 71 { 72 struct device_driver *drv = dev->driver; 73 74 if (drv) { 75 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj)); 76 sysfs_remove_link(&dev->kobj, "driver"); 77 } 78 } 79 80 /** 81 * device_bind_driver - bind a driver to one device. 82 * @dev: device. 83 * 84 * Allow manual attachment of a driver to a device. 85 * Caller must have already set @dev->driver. 86 * 87 * Note that this does not modify the bus reference count 88 * nor take the bus's rwsem. Please verify those are accounted 89 * for before calling this. (It is ok to call with no other effort 90 * from a driver's probe() method.) 91 * 92 * This function must be called with the device lock held. 93 */ 94 int device_bind_driver(struct device *dev) 95 { 96 int ret; 97 98 ret = driver_sysfs_add(dev); 99 if (!ret) 100 driver_bound(dev); 101 return ret; 102 } 103 EXPORT_SYMBOL_GPL(device_bind_driver); 104 105 static atomic_t probe_count = ATOMIC_INIT(0); 106 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue); 107 108 static int really_probe(struct device *dev, struct device_driver *drv) 109 { 110 int ret = 0; 111 112 atomic_inc(&probe_count); 113 pr_debug("bus: '%s': %s: probing driver %s with device %s\n", 114 drv->bus->name, __func__, drv->name, dev_name(dev)); 115 WARN_ON(!list_empty(&dev->devres_head)); 116 117 dev->driver = drv; 118 if (driver_sysfs_add(dev)) { 119 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n", 120 __func__, dev_name(dev)); 121 goto probe_failed; 122 } 123 124 if (dev->bus->probe) { 125 ret = dev->bus->probe(dev); 126 if (ret) 127 goto probe_failed; 128 } else if (drv->probe) { 129 ret = drv->probe(dev); 130 if (ret) 131 goto probe_failed; 132 } 133 134 driver_bound(dev); 135 ret = 1; 136 pr_debug("bus: '%s': %s: bound device %s to driver %s\n", 137 drv->bus->name, __func__, dev_name(dev), drv->name); 138 goto done; 139 140 probe_failed: 141 devres_release_all(dev); 142 driver_sysfs_remove(dev); 143 dev->driver = NULL; 144 145 if (ret != -ENODEV && ret != -ENXIO) { 146 /* driver matched but the probe failed */ 147 printk(KERN_WARNING 148 "%s: probe of %s failed with error %d\n", 149 drv->name, dev_name(dev), ret); 150 } else { 151 pr_debug("%s: probe of %s rejects match %d\n", 152 drv->name, dev_name(dev), ret); 153 } 154 /* 155 * Ignore errors returned by ->probe so that the next driver can try 156 * its luck. 157 */ 158 ret = 0; 159 done: 160 atomic_dec(&probe_count); 161 wake_up(&probe_waitqueue); 162 return ret; 163 } 164 165 /** 166 * driver_probe_done 167 * Determine if the probe sequence is finished or not. 168 * 169 * Should somehow figure out how to use a semaphore, not an atomic variable... 170 */ 171 int driver_probe_done(void) 172 { 173 pr_debug("%s: probe_count = %d\n", __func__, 174 atomic_read(&probe_count)); 175 if (atomic_read(&probe_count)) 176 return -EBUSY; 177 return 0; 178 } 179 180 /** 181 * wait_for_device_probe 182 * Wait for device probing to be completed. 183 */ 184 void wait_for_device_probe(void) 185 { 186 /* wait for the known devices to complete their probing */ 187 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0); 188 async_synchronize_full(); 189 } 190 EXPORT_SYMBOL_GPL(wait_for_device_probe); 191 192 /** 193 * driver_probe_device - attempt to bind device & driver together 194 * @drv: driver to bind a device to 195 * @dev: device to try to bind to the driver 196 * 197 * This function returns -ENODEV if the device is not registered, 198 * 1 if the device is bound successfully and 0 otherwise. 199 * 200 * This function must be called with @dev lock held. When called for a 201 * USB interface, @dev->parent lock must be held as well. 202 */ 203 int driver_probe_device(struct device_driver *drv, struct device *dev) 204 { 205 int ret = 0; 206 207 if (!device_is_registered(dev)) 208 return -ENODEV; 209 210 pr_debug("bus: '%s': %s: matched device %s with driver %s\n", 211 drv->bus->name, __func__, dev_name(dev), drv->name); 212 213 pm_runtime_get_noresume(dev); 214 pm_runtime_barrier(dev); 215 ret = really_probe(dev, drv); 216 pm_runtime_put_sync(dev); 217 218 return ret; 219 } 220 221 static int __device_attach(struct device_driver *drv, void *data) 222 { 223 struct device *dev = data; 224 225 if (!driver_match_device(drv, dev)) 226 return 0; 227 228 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 driver was found; 241 * -ENODEV if the device is not registered. 242 * 243 * When called for a USB interface, @dev->parent lock must be held. 244 */ 245 int device_attach(struct device *dev) 246 { 247 int ret = 0; 248 249 device_lock(dev); 250 if (dev->driver) { 251 if (klist_node_attached(&dev->p->knode_driver)) { 252 ret = 1; 253 goto out_unlock; 254 } 255 ret = device_bind_driver(dev); 256 if (ret == 0) 257 ret = 1; 258 else { 259 dev->driver = NULL; 260 ret = 0; 261 } 262 } else { 263 pm_runtime_get_noresume(dev); 264 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach); 265 pm_runtime_put_sync(dev); 266 } 267 out_unlock: 268 device_unlock(dev); 269 return ret; 270 } 271 EXPORT_SYMBOL_GPL(device_attach); 272 273 static int __driver_attach(struct device *dev, void *data) 274 { 275 struct device_driver *drv = data; 276 277 /* 278 * Lock device and try to bind to it. We drop the error 279 * here and always return 0, because we need to keep trying 280 * to bind to devices and some drivers will return an error 281 * simply if it didn't support the device. 282 * 283 * driver_probe_device() will spit a warning if there 284 * is an error. 285 */ 286 287 if (!driver_match_device(drv, dev)) 288 return 0; 289 290 if (dev->parent) /* Needed for USB */ 291 device_lock(dev->parent); 292 device_lock(dev); 293 if (!dev->driver) 294 driver_probe_device(drv, dev); 295 device_unlock(dev); 296 if (dev->parent) 297 device_unlock(dev->parent); 298 299 return 0; 300 } 301 302 /** 303 * driver_attach - try to bind driver to devices. 304 * @drv: driver. 305 * 306 * Walk the list of devices that the bus has on it and try to 307 * match the driver with each one. If driver_probe_device() 308 * returns 0 and the @dev->driver is set, we've found a 309 * compatible pair. 310 */ 311 int driver_attach(struct device_driver *drv) 312 { 313 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); 314 } 315 EXPORT_SYMBOL_GPL(driver_attach); 316 317 /* 318 * __device_release_driver() must be called with @dev lock held. 319 * When called for a USB interface, @dev->parent lock must be held as well. 320 */ 321 static void __device_release_driver(struct device *dev) 322 { 323 struct device_driver *drv; 324 325 drv = dev->driver; 326 if (drv) { 327 pm_runtime_get_sync(dev); 328 329 driver_sysfs_remove(dev); 330 331 if (dev->bus) 332 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 333 BUS_NOTIFY_UNBIND_DRIVER, 334 dev); 335 336 pm_runtime_put_sync(dev); 337 338 if (dev->bus && dev->bus->remove) 339 dev->bus->remove(dev); 340 else if (drv->remove) 341 drv->remove(dev); 342 devres_release_all(dev); 343 dev->driver = NULL; 344 klist_remove(&dev->p->knode_driver); 345 if (dev->bus) 346 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 347 BUS_NOTIFY_UNBOUND_DRIVER, 348 dev); 349 350 } 351 } 352 353 /** 354 * device_release_driver - manually detach device from driver. 355 * @dev: device. 356 * 357 * Manually detach device from driver. 358 * When called for a USB interface, @dev->parent lock must be held. 359 */ 360 void device_release_driver(struct device *dev) 361 { 362 /* 363 * If anyone calls device_release_driver() recursively from 364 * within their ->remove callback for the same device, they 365 * will deadlock right here. 366 */ 367 device_lock(dev); 368 __device_release_driver(dev); 369 device_unlock(dev); 370 } 371 EXPORT_SYMBOL_GPL(device_release_driver); 372 373 /** 374 * driver_detach - detach driver from all devices it controls. 375 * @drv: driver. 376 */ 377 void driver_detach(struct device_driver *drv) 378 { 379 struct device_private *dev_prv; 380 struct device *dev; 381 382 for (;;) { 383 spin_lock(&drv->p->klist_devices.k_lock); 384 if (list_empty(&drv->p->klist_devices.k_list)) { 385 spin_unlock(&drv->p->klist_devices.k_lock); 386 break; 387 } 388 dev_prv = list_entry(drv->p->klist_devices.k_list.prev, 389 struct device_private, 390 knode_driver.n_node); 391 dev = dev_prv->device; 392 get_device(dev); 393 spin_unlock(&drv->p->klist_devices.k_lock); 394 395 if (dev->parent) /* Needed for USB */ 396 device_lock(dev->parent); 397 device_lock(dev); 398 if (dev->driver == drv) 399 __device_release_driver(dev); 400 device_unlock(dev); 401 if (dev->parent) 402 device_unlock(dev->parent); 403 put_device(dev); 404 } 405 } 406 407 /* 408 * These exports can't be _GPL due to .h files using this within them, and it 409 * might break something that was previously working... 410 */ 411 void *dev_get_drvdata(const struct device *dev) 412 { 413 if (dev && dev->p) 414 return dev->p->driver_data; 415 return NULL; 416 } 417 EXPORT_SYMBOL(dev_get_drvdata); 418 419 int dev_set_drvdata(struct device *dev, void *data) 420 { 421 int error; 422 423 if (!dev->p) { 424 error = device_private_init(dev); 425 if (error) 426 return error; 427 } 428 dev->p->driver_data = data; 429 return 0; 430 } 431 EXPORT_SYMBOL(dev_set_drvdata); 432