drivers/base/dd.c

   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);