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->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->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  * Note: this function polls at 100 msec intervals.
 177  */
 178 int wait_for_device_probe(void)
 179 {
 180         /* wait for the known devices to complete their probing */
 181         while (driver_probe_done() != 0)
 182                 msleep(100);
 183         async_synchronize_full();
 184         return 0;
 185 }
 186
 187 /**
 188  * driver_probe_device - attempt to bind device & driver together
 189  * @drv: driver to bind a device to
 190  * @dev: device to try to bind to the driver
 191  *
 192  * First, we call the bus's match function, if one present, which should
 193  * compare the device IDs the driver supports with the device IDs of the
 194  * device. Note we don't do this ourselves because we don't know the
 195  * format of the ID structures, nor what is to be considered a match and
 196  * what is not.
 197  *
 198  * This function returns 1 if a match is found, -ENODEV if the device is
 199  * not registered, and 0 otherwise.
 200  *
 201  * This function must be called with @dev->sem held.  When called for a
 202  * USB interface, @dev->parent->sem must be held as well.
 203  */
 204 int driver_probe_device(struct device_driver *drv, struct device *dev)
 205 {
 206         int ret = 0;
 207
 208         if (!device_is_registered(dev))
 209                 return -ENODEV;
 210         if (drv->bus->match && !drv->bus->match(dev, drv))
 211                 goto done;
 212
 213         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 214                  drv->bus->name, __func__, dev_name(dev), drv->name);
 215
 216         ret = really_probe(dev, drv);
 217
 218 done:
 219         return ret;
 220 }
 221
 222 static int __device_attach(struct device_driver *drv, void *data)
 223 {
 224         struct device *dev = data;
 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 device was found;
 238  * -ENODEV if the device is not registered.
 239  *
 240  * When called for a USB interface, @dev->parent->sem must be held.
 241  */
 242 int device_attach(struct device *dev)
 243 {
 244         int ret = 0;
 245
 246         down(&dev->sem);
 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                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
 257         }
 258         up(&dev->sem);
 259         return ret;
 260 }
 261 EXPORT_SYMBOL_GPL(device_attach);
 262
 263 static int __driver_attach(struct device *dev, void *data)
 264 {
 265         struct device_driver *drv = data;
 266
 267         /*
 268          * Lock device and try to bind to it. We drop the error
 269          * here and always return 0, because we need to keep trying
 270          * to bind to devices and some drivers will return an error
 271          * simply if it didn't support the device.
 272          *
 273          * driver_probe_device() will spit a warning if there
 274          * is an error.
 275          */
 276
 277         if (drv->bus->match && !drv->bus->match(dev, drv))
 278                 return 0;
 279
 280         if (dev->parent)        /* Needed for USB */
 281                 down(&dev->parent->sem);
 282         down(&dev->sem);
 283         if (!dev->driver)
 284                 driver_probe_device(drv, dev);
 285         up(&dev->sem);
 286         if (dev->parent)
 287                 up(&dev->parent->sem);
 288
 289         return 0;
 290 }
 291
 292 /**
 293  * driver_attach - try to bind driver to devices.
 294  * @drv: driver.
 295  *
 296  * Walk the list of devices that the bus has on it and try to
 297  * match the driver with each one.  If driver_probe_device()
 298  * returns 0 and the @dev->driver is set, we've found a
 299  * compatible pair.
 300  */
 301 int driver_attach(struct device_driver *drv)
 302 {
 303         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 304 }
 305 EXPORT_SYMBOL_GPL(driver_attach);
 306
 307 /*
 308  * __device_release_driver() must be called with @dev->sem held.
 309  * When called for a USB interface, @dev->parent->sem must be held as well.
 310  */
 311 static void __device_release_driver(struct device *dev)
 312 {
 313         struct device_driver *drv;
 314
 315         drv = dev->driver;
 316         if (drv) {
 317                 driver_sysfs_remove(dev);
 318
 319                 if (dev->bus)
 320                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 321                                                      BUS_NOTIFY_UNBIND_DRIVER,
 322                                                      dev);
 323
 324                 if (dev->bus && dev->bus->remove)
 325                         dev->bus->remove(dev);
 326                 else if (drv->remove)
 327                         drv->remove(dev);
 328                 devres_release_all(dev);
 329                 dev->driver = NULL;
 330                 klist_remove(&dev->knode_driver);
 331         }
 332 }
 333
 334 /**
 335  * device_release_driver - manually detach device from driver.
 336  * @dev: device.
 337  *
 338  * Manually detach device from driver.
 339  * When called for a USB interface, @dev->parent->sem must be held.
 340  */
 341 void device_release_driver(struct device *dev)
 342 {
 343         /*
 344          * If anyone calls device_release_driver() recursively from
 345          * within their ->remove callback for the same device, they
 346          * will deadlock right here.
 347          */
 348         down(&dev->sem);
 349         __device_release_driver(dev);
 350         up(&dev->sem);
 351 }
 352 EXPORT_SYMBOL_GPL(device_release_driver);
 353
 354 /**
 355  * driver_detach - detach driver from all devices it controls.
 356  * @drv: driver.
 357  */
 358 void driver_detach(struct device_driver *drv)
 359 {
 360         struct device *dev;
 361
 362         for (;;) {
 363                 spin_lock(&drv->p->klist_devices.k_lock);
 364                 if (list_empty(&drv->p->klist_devices.k_list)) {
 365                         spin_unlock(&drv->p->klist_devices.k_lock);
 366                         break;
 367                 }
 368                 dev = list_entry(drv->p->klist_devices.k_list.prev,
 369                                 struct device, knode_driver.n_node);
 370                 get_device(dev);
 371                 spin_unlock(&drv->p->klist_devices.k_lock);
 372
 373                 if (dev->parent)        /* Needed for USB */
 374                         down(&dev->parent->sem);
 375                 down(&dev->sem);
 376                 if (dev->driver == drv)
 377                         __device_release_driver(dev);
 378                 up(&dev->sem);
 379                 if (dev->parent)
 380                         up(&dev->parent->sem);
 381                 put_device(dev);
 382         }
 383 }