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 Greg Kroah-Hartman <gregkh@suse.de>
  15  * Copyright (c) 2007 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
  27 #include "base.h"
  28 #include "power/power.h"
  29
  30
  31 static void driver_bound(struct device *dev)
  32 {
  33         if (klist_node_attached(&dev->p->knode_driver)) {
  34                 printk(KERN_WARNING "%s: device %s already bound\n",
  35                         __func__, kobject_name(&dev->kobj));
  36                 return;
  37         }
  38
  39         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev_name(dev),
  40                  __func__, dev->driver->name);
  41
  42         if (dev->bus)
  43                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
  44                                              BUS_NOTIFY_BOUND_DRIVER, dev);
  45
  46         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
  47 }
  48
  49 static int driver_sysfs_add(struct device *dev)
  50 {
  51         int ret;
  52
  53         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
  54                           kobject_name(&dev->kobj));
  55         if (ret == 0) {
  56                 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
  57                                         "driver");
  58                 if (ret)
  59                         sysfs_remove_link(&dev->driver->p->kobj,
  60                                         kobject_name(&dev->kobj));
  61         }
  62         return ret;
  63 }
  64
  65 static void driver_sysfs_remove(struct device *dev)
  66 {
  67         struct device_driver *drv = dev->driver;
  68
  69         if (drv) {
  70                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
  71                 sysfs_remove_link(&dev->kobj, "driver");
  72         }
  73 }
  74
  75 /**
  76  * device_bind_driver - bind a driver to one device.
  77  * @dev: device.
  78  *
  79  * Allow manual attachment of a driver to a device.
  80  * Caller must have already set @dev->driver.
  81  *
  82  * Note that this does not modify the bus reference count
  83  * nor take the bus's rwsem. Please verify those are accounted
  84  * for before calling this. (It is ok to call with no other effort
  85  * from a driver's probe() method.)
  86  *
  87  * This function must be called with @dev->sem held.
  88  */
  89 int device_bind_driver(struct device *dev)
  90 {
  91         int ret;
  92
  93         ret = driver_sysfs_add(dev);
  94         if (!ret)
  95                 driver_bound(dev);
  96         return ret;
  97 }
  98 EXPORT_SYMBOL_GPL(device_bind_driver);
  99
 100 static atomic_t probe_count = ATOMIC_INIT(0);
 101 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 102
 103 static int really_probe(struct device *dev, struct device_driver *drv)
 104 {
 105         int ret = 0;
 106
 107         atomic_inc(&probe_count);
 108         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 109                  drv->bus->name, __func__, drv->name, dev_name(dev));
 110         WARN_ON(!list_empty(&dev->devres_head));
 111
 112         dev->driver = drv;
 113         if (driver_sysfs_add(dev)) {
 114                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 115                         __func__, dev_name(dev));
 116                 goto probe_failed;
 117         }
 118
 119         if (dev->bus->probe) {
 120                 ret = dev->bus->probe(dev);
 121                 if (ret)
 122                         goto probe_failed;
 123         } else if (drv->probe) {
 124                 ret = drv->probe(dev);
 125                 if (ret)
 126                         goto probe_failed;
 127         }
 128
 129         driver_bound(dev);
 130         ret = 1;
 131         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 132                  drv->bus->name, __func__, dev_name(dev), drv->name);
 133         goto done;
 134
 135 probe_failed:
 136         devres_release_all(dev);
 137         driver_sysfs_remove(dev);
 138         dev->driver = NULL;
 139
 140         if (ret != -ENODEV && ret != -ENXIO) {
 141                 /* driver matched but the probe failed */
 142                 printk(KERN_WARNING
 143                        "%s: probe of %s failed with error %d\n",
 144                        drv->name, dev_name(dev), ret);
 145         }
 146         /*
 147          * Ignore errors returned by ->probe so that the next driver can try
 148          * its luck.
 149          */
 150         ret = 0;
 151 done:
 152         atomic_dec(&probe_count);
 153         wake_up(&probe_waitqueue);
 154         return ret;
 155 }
 156
 157 /**
 158  * driver_probe_done
 159  * Determine if the probe sequence is finished or not.
 160  *
 161  * Should somehow figure out how to use a semaphore, not an atomic variable...
 162  */
 163 int driver_probe_done(void)
 164 {
 165         pr_debug("%s: probe_count = %d\n", __func__,
 166                  atomic_read(&probe_count));
 167         if (atomic_read(&probe_count))
 168                 return -EBUSY;
 169         return 0;
 170 }
 171
 172 /**
 173  * wait_for_device_probe
 174  * Wait for device probing to be completed.
 175  */
 176 void wait_for_device_probe(void)
 177 {
 178         /* wait for the known devices to complete their probing */
 179         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
 180         async_synchronize_full();
 181 }
 182 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 183
 184 /**
 185  * driver_probe_device - attempt to bind device & driver together
 186  * @drv: driver to bind a device to
 187  * @dev: device to try to bind to the driver
 188  *
 189  * This function returns -ENODEV if the device is not registered,
 190  * 1 if the device is bound sucessfully and 0 otherwise.
 191  *
 192  * This function must be called with @dev->sem held.  When called for a
 193  * USB interface, @dev->parent->sem must be held as well.
 194  */
 195 int driver_probe_device(struct device_driver *drv, struct device *dev)
 196 {
 197         int ret = 0;
 198
 199         if (!device_is_registered(dev))
 200                 return -ENODEV;
 201
 202         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 203                  drv->bus->name, __func__, dev_name(dev), drv->name);
 204
 205         ret = really_probe(dev, drv);
 206
 207         return ret;
 208 }
 209
 210 static int __device_attach(struct device_driver *drv, void *data)
 211 {
 212         struct device *dev = data;
 213
 214         if (!driver_match_device(drv, dev))
 215                 return 0;
 216
 217         return driver_probe_device(drv, dev);
 218 }
 219
 220 /**
 221  * device_attach - try to attach device to a driver.
 222  * @dev: device.
 223  *
 224  * Walk the list of drivers that the bus has and call
 225  * driver_probe_device() for each pair. If a compatible
 226  * pair is found, break out and return.
 227  *
 228  * Returns 1 if the device was bound to a driver;
 229  * 0 if no matching device was found;
 230  * -ENODEV if the device is not registered.
 231  *
 232  * When called for a USB interface, @dev->parent->sem must be held.
 233  */
 234 int device_attach(struct device *dev)
 235 {
 236         int ret = 0;
 237
 238         down(&dev->sem);
 239         if (dev->driver) {
 240                 ret = device_bind_driver(dev);
 241                 if (ret == 0)
 242                         ret = 1;
 243                 else {
 244                         dev->driver = NULL;
 245                         ret = 0;
 246                 }
 247         } else {
 248                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
 249         }
 250         up(&dev->sem);
 251         return ret;
 252 }
 253 EXPORT_SYMBOL_GPL(device_attach);
 254
 255 static int __driver_attach(struct device *dev, void *data)
 256 {
 257         struct device_driver *drv = data;
 258
 259         /*
 260          * Lock device and try to bind to it. We drop the error
 261          * here and always return 0, because we need to keep trying
 262          * to bind to devices and some drivers will return an error
 263          * simply if it didn't support the device.
 264          *
 265          * driver_probe_device() will spit a warning if there
 266          * is an error.
 267          */
 268
 269         if (!driver_match_device(drv, dev))
 270                 return 0;
 271
 272         if (dev->parent)        /* Needed for USB */
 273                 down(&dev->parent->sem);
 274         down(&dev->sem);
 275         if (!dev->driver)
 276                 driver_probe_device(drv, dev);
 277         up(&dev->sem);
 278         if (dev->parent)
 279                 up(&dev->parent->sem);
 280
 281         return 0;
 282 }
 283
 284 /**
 285  * driver_attach - try to bind driver to devices.
 286  * @drv: driver.
 287  *
 288  * Walk the list of devices that the bus has on it and try to
 289  * match the driver with each one.  If driver_probe_device()
 290  * returns 0 and the @dev->driver is set, we've found a
 291  * compatible pair.
 292  */
 293 int driver_attach(struct device_driver *drv)
 294 {
 295         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 296 }
 297 EXPORT_SYMBOL_GPL(driver_attach);
 298
 299 /*
 300  * __device_release_driver() must be called with @dev->sem held.
 301  * When called for a USB interface, @dev->parent->sem must be held as well.
 302  */
 303 static void __device_release_driver(struct device *dev)
 304 {
 305         struct device_driver *drv;
 306
 307         drv = dev->driver;
 308         if (drv) {
 309                 driver_sysfs_remove(dev);
 310
 311                 if (dev->bus)
 312                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 313                                                      BUS_NOTIFY_UNBIND_DRIVER,
 314                                                      dev);
 315
 316                 if (dev->bus && dev->bus->remove)
 317                         dev->bus->remove(dev);
 318                 else if (drv->remove)
 319                         drv->remove(dev);
 320                 devres_release_all(dev);
 321                 dev->driver = NULL;
 322                 klist_remove(&dev->p->knode_driver);
 323         }
 324 }
 325
 326 /**
 327  * device_release_driver - manually detach device from driver.
 328  * @dev: device.
 329  *
 330  * Manually detach device from driver.
 331  * When called for a USB interface, @dev->parent->sem must be held.
 332  */
 333 void device_release_driver(struct device *dev)
 334 {
 335         /*
 336          * If anyone calls device_release_driver() recursively from
 337          * within their ->remove callback for the same device, they
 338          * will deadlock right here.
 339          */
 340         down(&dev->sem);
 341         __device_release_driver(dev);
 342         up(&dev->sem);
 343 }
 344 EXPORT_SYMBOL_GPL(device_release_driver);
 345
 346 /**
 347  * driver_detach - detach driver from all devices it controls.
 348  * @drv: driver.
 349  */
 350 void driver_detach(struct device_driver *drv)
 351 {
 352         struct device_private *dev_prv;
 353         struct device *dev;
 354
 355         for (;;) {
 356                 spin_lock(&drv->p->klist_devices.k_lock);
 357                 if (list_empty(&drv->p->klist_devices.k_list)) {
 358                         spin_unlock(&drv->p->klist_devices.k_lock);
 359                         break;
 360                 }
 361                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
 362                                      struct device_private,
 363                                      knode_driver.n_node);
 364                 dev = dev_prv->device;
 365                 get_device(dev);
 366                 spin_unlock(&drv->p->klist_devices.k_lock);
 367
 368                 if (dev->parent)        /* Needed for USB */
 369                         down(&dev->parent->sem);
 370                 down(&dev->sem);
 371                 if (dev->driver == drv)
 372                         __device_release_driver(dev);
 373                 up(&dev->sem);
 374                 if (dev->parent)
 375                         up(&dev->parent->sem);
 376                 put_device(dev);
 377         }
 378 }