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 <[email protected]>
  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);