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 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj, 55 kobject_name(&dev->kobj)); 56 if (ret == 0) { 57 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj, 58 "driver"); 59 if (ret) 60 sysfs_remove_link(&dev->driver->p->kobj, 61 kobject_name(&dev->kobj)); 62 } 63 return ret; 64 } 65 66 static void driver_sysfs_remove(struct device *dev) 67 { 68 struct device_driver *drv = dev->driver; 69 70 if (drv) { 71 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj)); 72 sysfs_remove_link(&dev->kobj, "driver"); 73 } 74 } 75 76 /** 77 * device_bind_driver - bind a driver to one device. 78 * @dev: device. 79 * 80 * Allow manual attachment of a driver to a device. 81 * Caller must have already set @dev->driver. 82 * 83 * Note that this does not modify the bus reference count 84 * nor take the bus's rwsem. Please verify those are accounted 85 * for before calling this. (It is ok to call with no other effort 86 * from a driver's probe() method.) 87 * 88 * This function must be called with the device lock held. 89 */ 90 int device_bind_driver(struct device *dev) 91 { 92 int ret; 93 94 ret = driver_sysfs_add(dev); 95 if (!ret) 96 driver_bound(dev); 97 return ret; 98 } 99 EXPORT_SYMBOL_GPL(device_bind_driver); 100 101 static atomic_t probe_count = ATOMIC_INIT(0); 102 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue); 103 104 static int really_probe(struct device *dev, struct device_driver *drv) 105 { 106 int ret = 0; 107 108 atomic_inc(&probe_count); 109 pr_debug("bus: '%s': %s: probing driver %s with device %s\n", 110 drv->bus->name, __func__, drv->name, dev_name(dev)); 111 WARN_ON(!list_empty(&dev->devres_head)); 112 113 dev->driver = drv; 114 if (driver_sysfs_add(dev)) { 115 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n", 116 __func__, dev_name(dev)); 117 goto probe_failed; 118 } 119 120 if (dev->bus->probe) { 121 ret = dev->bus->probe(dev); 122 if (ret) 123 goto probe_failed; 124 } else if (drv->probe) { 125 ret = drv->probe(dev); 126 if (ret) 127 goto probe_failed; 128 } 129 130 driver_bound(dev); 131 ret = 1; 132 pr_debug("bus: '%s': %s: bound device %s to driver %s\n", 133 drv->bus->name, __func__, dev_name(dev), drv->name); 134 goto done; 135 136 probe_failed: 137 devres_release_all(dev); 138 driver_sysfs_remove(dev); 139 dev->driver = NULL; 140 141 if (ret != -ENODEV && ret != -ENXIO) { 142 /* driver matched but the probe failed */ 143 printk(KERN_WARNING 144 "%s: probe of %s failed with error %d\n", 145 drv->name, dev_name(dev), ret); 146 } 147 /* 148 * Ignore errors returned by ->probe so that the next driver can try 149 * its luck. 150 */ 151 ret = 0; 152 done: 153 atomic_dec(&probe_count); 154 wake_up(&probe_waitqueue); 155 return ret; 156 } 157 158 /** 159 * driver_probe_done 160 * Determine if the probe sequence is finished or not. 161 * 162 * Should somehow figure out how to use a semaphore, not an atomic variable... 163 */ 164 int driver_probe_done(void) 165 { 166 pr_debug("%s: probe_count = %d\n", __func__, 167 atomic_read(&probe_count)); 168 if (atomic_read(&probe_count)) 169 return -EBUSY; 170 return 0; 171 } 172 173 /** 174 * wait_for_device_probe 175 * Wait for device probing to be completed. 176 */ 177 void wait_for_device_probe(void) 178 { 179 /* wait for the known devices to complete their probing */ 180 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0); 181 async_synchronize_full(); 182 } 183 EXPORT_SYMBOL_GPL(wait_for_device_probe); 184 185 /** 186 * driver_probe_device - attempt to bind device & driver together 187 * @drv: driver to bind a device to 188 * @dev: device to try to bind to the driver 189 * 190 * This function returns -ENODEV if the device is not registered, 191 * 1 if the device is bound successfully and 0 otherwise. 192 * 193 * This function must be called with @dev lock held. When called for a 194 * USB interface, @dev->parent lock must be held as well. 195 */ 196 int driver_probe_device(struct device_driver *drv, struct device *dev) 197 { 198 int ret = 0; 199 200 if (!device_is_registered(dev)) 201 return -ENODEV; 202 203 pr_debug("bus: '%s': %s: matched device %s with driver %s\n", 204 drv->bus->name, __func__, dev_name(dev), drv->name); 205 206 pm_runtime_get_noresume(dev); 207 pm_runtime_barrier(dev); 208 ret = really_probe(dev, drv); 209 pm_runtime_put_sync(dev); 210 211 return ret; 212 } 213 214 static int __device_attach(struct device_driver *drv, void *data) 215 { 216 struct device *dev = data; 217 218 if (!driver_match_device(drv, dev)) 219 return 0; 220 221 return driver_probe_device(drv, dev); 222 } 223 224 /** 225 * device_attach - try to attach device to a driver. 226 * @dev: device. 227 * 228 * Walk the list of drivers that the bus has and call 229 * driver_probe_device() for each pair. If a compatible 230 * pair is found, break out and return. 231 * 232 * Returns 1 if the device was bound to a driver; 233 * 0 if no matching driver was found; 234 * -ENODEV if the device is not registered. 235 * 236 * When called for a USB interface, @dev->parent lock must be held. 237 */ 238 int device_attach(struct device *dev) 239 { 240 int ret = 0; 241 242 device_lock(dev); 243 if (dev->driver) { 244 ret = device_bind_driver(dev); 245 if (ret == 0) 246 ret = 1; 247 else { 248 dev->driver = NULL; 249 ret = 0; 250 } 251 } else { 252 pm_runtime_get_noresume(dev); 253 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach); 254 pm_runtime_put_sync(dev); 255 } 256 device_unlock(dev); 257 return ret; 258 } 259 EXPORT_SYMBOL_GPL(device_attach); 260 261 static int __driver_attach(struct device *dev, void *data) 262 { 263 struct device_driver *drv = data; 264 265 /* 266 * Lock device and try to bind to it. We drop the error 267 * here and always return 0, because we need to keep trying 268 * to bind to devices and some drivers will return an error 269 * simply if it didn't support the device. 270 * 271 * driver_probe_device() will spit a warning if there 272 * is an error. 273 */ 274 275 if (!driver_match_device(drv, dev)) 276 return 0; 277 278 if (dev->parent) /* Needed for USB */ 279 device_lock(dev->parent); 280 device_lock(dev); 281 if (!dev->driver) 282 driver_probe_device(drv, dev); 283 device_unlock(dev); 284 if (dev->parent) 285 device_unlock(dev->parent); 286 287 return 0; 288 } 289 290 /** 291 * driver_attach - try to bind driver to devices. 292 * @drv: driver. 293 * 294 * Walk the list of devices that the bus has on it and try to 295 * match the driver with each one. If driver_probe_device() 296 * returns 0 and the @dev->driver is set, we've found a 297 * compatible pair. 298 */ 299 int driver_attach(struct device_driver *drv) 300 { 301 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); 302 } 303 EXPORT_SYMBOL_GPL(driver_attach); 304 305 /* 306 * __device_release_driver() must be called with @dev lock held. 307 * When called for a USB interface, @dev->parent lock must be held as well. 308 */ 309 static void __device_release_driver(struct device *dev) 310 { 311 struct device_driver *drv; 312 313 drv = dev->driver; 314 if (drv) { 315 pm_runtime_get_noresume(dev); 316 pm_runtime_barrier(dev); 317 318 driver_sysfs_remove(dev); 319 320 if (dev->bus) 321 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 322 BUS_NOTIFY_UNBIND_DRIVER, 323 dev); 324 325 if (dev->bus && dev->bus->remove) 326 dev->bus->remove(dev); 327 else if (drv->remove) 328 drv->remove(dev); 329 devres_release_all(dev); 330 dev->driver = NULL; 331 klist_remove(&dev->p->knode_driver); 332 if (dev->bus) 333 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 334 BUS_NOTIFY_UNBOUND_DRIVER, 335 dev); 336 337 pm_runtime_put_sync(dev); 338 } 339 } 340 341 /** 342 * device_release_driver - manually detach device from driver. 343 * @dev: device. 344 * 345 * Manually detach device from driver. 346 * When called for a USB interface, @dev->parent lock must be held. 347 */ 348 void device_release_driver(struct device *dev) 349 { 350 /* 351 * If anyone calls device_release_driver() recursively from 352 * within their ->remove callback for the same device, they 353 * will deadlock right here. 354 */ 355 device_lock(dev); 356 __device_release_driver(dev); 357 device_unlock(dev); 358 } 359 EXPORT_SYMBOL_GPL(device_release_driver); 360 361 /** 362 * driver_detach - detach driver from all devices it controls. 363 * @drv: driver. 364 */ 365 void driver_detach(struct device_driver *drv) 366 { 367 struct device_private *dev_prv; 368 struct device *dev; 369 370 for (;;) { 371 spin_lock(&drv->p->klist_devices.k_lock); 372 if (list_empty(&drv->p->klist_devices.k_list)) { 373 spin_unlock(&drv->p->klist_devices.k_lock); 374 break; 375 } 376 dev_prv = list_entry(drv->p->klist_devices.k_list.prev, 377 struct device_private, 378 knode_driver.n_node); 379 dev = dev_prv->device; 380 get_device(dev); 381 spin_unlock(&drv->p->klist_devices.k_lock); 382 383 if (dev->parent) /* Needed for USB */ 384 device_lock(dev->parent); 385 device_lock(dev); 386 if (dev->driver == drv) 387 __device_release_driver(dev); 388 device_unlock(dev); 389 if (dev->parent) 390 device_unlock(dev->parent); 391 put_device(dev); 392 } 393 } 394 395 /* 396 * These exports can't be _GPL due to .h files using this within them, and it 397 * might break something that was previously working... 398 */ 399 void *dev_get_drvdata(const struct device *dev) 400 { 401 if (dev && dev->p) 402 return dev->p->driver_data; 403 return NULL; 404 } 405 EXPORT_SYMBOL(dev_get_drvdata); 406 407 void dev_set_drvdata(struct device *dev, void *data) 408 { 409 int error; 410 411 if (!dev) 412 return; 413 if (!dev->p) { 414 error = device_private_init(dev); 415 if (error) 416 return; 417 } 418 dev->p->driver_data = data; 419 } 420 EXPORT_SYMBOL(dev_set_drvdata); 421