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 32static 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 50static 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 70static 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 */ 94int 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} 103EXPORT_SYMBOL_GPL(device_bind_driver); 104 105static atomic_t probe_count = ATOMIC_INIT(0); 106static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue); 107 108static 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 140probe_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 } 151 /* 152 * Ignore errors returned by ->probe so that the next driver can try 153 * its luck. 154 */ 155 ret = 0; 156done: 157 atomic_dec(&probe_count); 158 wake_up(&probe_waitqueue); 159 return ret; 160} 161 162/** 163 * driver_probe_done 164 * Determine if the probe sequence is finished or not. 165 * 166 * Should somehow figure out how to use a semaphore, not an atomic variable... 167 */ 168int driver_probe_done(void) 169{ 170 pr_debug("%s: probe_count = %d\n", __func__, 171 atomic_read(&probe_count)); 172 if (atomic_read(&probe_count)) 173 return -EBUSY; 174 return 0; 175} 176 177/** 178 * wait_for_device_probe 179 * Wait for device probing to be completed. 180 */ 181void wait_for_device_probe(void) 182{ 183 /* wait for the known devices to complete their probing */ 184 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0); 185 async_synchronize_full(); 186} 187EXPORT_SYMBOL_GPL(wait_for_device_probe); 188 189/** 190 * driver_probe_device - attempt to bind device & driver together 191 * @drv: driver to bind a device to 192 * @dev: device to try to bind to the driver 193 * 194 * This function returns -ENODEV if the device is not registered, 195 * 1 if the device is bound successfully and 0 otherwise. 196 * 197 * This function must be called with @dev lock held. When called for a 198 * USB interface, @dev->parent lock must be held as well. 199 */ 200int driver_probe_device(struct device_driver *drv, struct device *dev) 201{ 202 int ret = 0; 203 204 if (!device_is_registered(dev)) 205 return -ENODEV; 206 207 pr_debug("bus: '%s': %s: matched device %s with driver %s\n", 208 drv->bus->name, __func__, dev_name(dev), drv->name); 209 210 pm_runtime_get_noresume(dev); 211 pm_runtime_barrier(dev); 212 ret = really_probe(dev, drv); 213 pm_runtime_put_sync(dev); 214 215 return ret; 216} 217 218static int __device_attach(struct device_driver *drv, void *data) 219{ 220 struct device *dev = data; 221 222 if (!driver_match_device(drv, dev)) 223 return 0; 224 225 return driver_probe_device(drv, dev); 226} 227 228/** 229 * device_attach - try to attach device to a driver. 230 * @dev: device. 231 * 232 * Walk the list of drivers that the bus has and call 233 * driver_probe_device() for each pair. If a compatible 234 * pair is found, break out and return. 235 * 236 * Returns 1 if the device was bound to a driver; 237 * 0 if no matching driver was found; 238 * -ENODEV if the device is not registered. 239 * 240 * When called for a USB interface, @dev->parent lock must be held. 241 */ 242int device_attach(struct device *dev) 243{ 244 int ret = 0; 245 246 device_lock(dev); 247 if (dev->driver) { 248 ret = device_bind_driver(dev); 249 if (ret == 0) 250 ret = 1; 251 else { 252 dev->driver = NULL; 253 ret = 0; 254 } 255 } else { 256 pm_runtime_get_noresume(dev); 257 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach); 258 pm_runtime_put_sync(dev); 259 } 260 device_unlock(dev); 261 return ret; 262} 263EXPORT_SYMBOL_GPL(device_attach); 264 265static int __driver_attach(struct device *dev, void *data) 266{ 267 struct device_driver *drv = data; 268 269 /* 270 * Lock device and try to bind to it. We drop the error 271 * here and always return 0, because we need to keep trying 272 * to bind to devices and some drivers will return an error 273 * simply if it didn't support the device. 274 * 275 * driver_probe_device() will spit a warning if there 276 * is an error. 277 */ 278 279 if (!driver_match_device(drv, dev)) 280 return 0; 281 282 if (dev->parent) /* Needed for USB */ 283 device_lock(dev->parent); 284 device_lock(dev); 285 if (!dev->driver) 286 driver_probe_device(drv, dev); 287 device_unlock(dev); 288 if (dev->parent) 289 device_unlock(dev->parent); 290 291 return 0; 292} 293 294/** 295 * driver_attach - try to bind driver to devices. 296 * @drv: driver. 297 * 298 * Walk the list of devices that the bus has on it and try to 299 * match the driver with each one. If driver_probe_device() 300 * returns 0 and the @dev->driver is set, we've found a 301 * compatible pair. 302 */ 303int driver_attach(struct device_driver *drv) 304{ 305 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); 306} 307EXPORT_SYMBOL_GPL(driver_attach); 308 309/* 310 * __device_release_driver() must be called with @dev lock held. 311 * When called for a USB interface, @dev->parent lock must be held as well. 312 */ 313static void __device_release_driver(struct device *dev) 314{ 315 struct device_driver *drv; 316 317 drv = dev->driver; 318 if (drv) { 319 pm_runtime_get_noresume(dev); 320 pm_runtime_barrier(dev); 321 322 driver_sysfs_remove(dev); 323 324 if (dev->bus) 325 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 326 BUS_NOTIFY_UNBIND_DRIVER, 327 dev); 328 329 if (dev->bus && dev->bus->remove) 330 dev->bus->remove(dev); 331 else if (drv->remove) 332 drv->remove(dev); 333 devres_release_all(dev); 334 dev->driver = NULL; 335 klist_remove(&dev->p->knode_driver); 336 if (dev->bus) 337 blocking_notifier_call_chain(&dev->bus->p->bus_notifier, 338 BUS_NOTIFY_UNBOUND_DRIVER, 339 dev); 340 341 pm_runtime_put_sync(dev); 342 } 343} 344 345/** 346 * device_release_driver - manually detach device from driver. 347 * @dev: device. 348 * 349 * Manually detach device from driver. 350 * When called for a USB interface, @dev->parent lock must be held. 351 */ 352void device_release_driver(struct device *dev) 353{ 354 /* 355 * If anyone calls device_release_driver() recursively from 356 * within their ->remove callback for the same device, they 357 * will deadlock right here. 358 */ 359 device_lock(dev); 360 __device_release_driver(dev); 361 device_unlock(dev); 362} 363EXPORT_SYMBOL_GPL(device_release_driver); 364 365/** 366 * driver_detach - detach driver from all devices it controls. 367 * @drv: driver. 368 */ 369void driver_detach(struct device_driver *drv) 370{ 371 struct device_private *dev_prv; 372 struct device *dev; 373 374 for (;;) { 375 spin_lock(&drv->p->klist_devices.k_lock); 376 if (list_empty(&drv->p->klist_devices.k_list)) { 377 spin_unlock(&drv->p->klist_devices.k_lock); 378 break; 379 } 380 dev_prv = list_entry(drv->p->klist_devices.k_list.prev, 381 struct device_private, 382 knode_driver.n_node); 383 dev = dev_prv->device; 384 get_device(dev); 385 spin_unlock(&drv->p->klist_devices.k_lock); 386 387 if (dev->parent) /* Needed for USB */ 388 device_lock(dev->parent); 389 device_lock(dev); 390 if (dev->driver == drv) 391 __device_release_driver(dev); 392 device_unlock(dev); 393 if (dev->parent) 394 device_unlock(dev->parent); 395 put_device(dev); 396 } 397} 398 399/* 400 * These exports can't be _GPL due to .h files using this within them, and it 401 * might break something that was previously working... 402 */ 403void *dev_get_drvdata(const struct device *dev) 404{ 405 if (dev && dev->p) 406 return dev->p->driver_data; 407 return NULL; 408} 409EXPORT_SYMBOL(dev_get_drvdata); 410 411void dev_set_drvdata(struct device *dev, void *data) 412{ 413 int error; 414 415 if (!dev) 416 return; 417 if (!dev->p) { 418 error = device_private_init(dev); 419 if (error) 420 return; 421 } 422 dev->p->driver_data = data; 423} 424EXPORT_SYMBOL(dev_set_drvdata); 425