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/module.h>
  22 #include <linux/kthread.h>
  23 #include <linux/wait.h>
  24
  25 #include "base.h"
  26 #include "power/power.h"
  27
  28
  29 static void driver_bound(struct device *dev)
  30 {
  31         if (klist_node_attached(&dev->knode_driver)) {
  32                 printk(KERN_WARNING "%s: device %s already bound\n",
  33                         __func__, kobject_name(&dev->kobj));
  34                 return;
  35         }
  36
  37         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->bus_id,
  38                  __func__, dev->driver->name);
  39
  40         if (dev->bus)
  41                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
  42                                              BUS_NOTIFY_BOUND_DRIVER, dev);
  43
  44         klist_add_tail(&dev->knode_driver, &dev->driver->p->klist_devices);
  45 }
  46
  47 static int driver_sysfs_add(struct device *dev)
  48 {
  49         int ret;
  50
  51         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
  52                           kobject_name(&dev->kobj));
  53         if (ret == 0) {
  54                 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
  55                                         "driver");
  56                 if (ret)
  57                         sysfs_remove_link(&dev->driver->p->kobj,
  58                                         kobject_name(&dev->kobj));
  59         }
  60         return ret;
  61 }
  62
  63 static void driver_sysfs_remove(struct device *dev)
  64 {
  65         struct device_driver *drv = dev->driver;
  66
  67         if (drv) {
  68                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
  69                 sysfs_remove_link(&dev->kobj, "driver");
  70         }
  71 }
  72
  73 /**
  74  * device_bind_driver - bind a driver to one device.
  75  * @dev: device.
  76  *
  77  * Allow manual attachment of a driver to a device.
  78  * Caller must have already set @dev->driver.
  79  *
  80  * Note that this does not modify the bus reference count
  81  * nor take the bus's rwsem. Please verify those are accounted
  82  * for before calling this. (It is ok to call with no other effort
  83  * from a driver's probe() method.)
  84  *
  85  * This function must be called with @dev->sem held.
  86  */
  87 int device_bind_driver(struct device *dev)
  88 {
  89         int ret;
  90
  91         ret = driver_sysfs_add(dev);
  92         if (!ret)
  93                 driver_bound(dev);
  94         return ret;
  95 }
  96 EXPORT_SYMBOL_GPL(device_bind_driver);
  97
  98 static atomic_t probe_count = ATOMIC_INIT(0);
  99 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 100
 101 static int really_probe(struct device *dev, struct device_driver *drv)
 102 {
 103         int ret = 0;
 104
 105         atomic_inc(&probe_count);
 106         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 107                  drv->bus->name, __func__, drv->name, dev->bus_id);
 108         WARN_ON(!list_empty(&dev->devres_head));
 109
 110         dev->driver = drv;
 111         if (driver_sysfs_add(dev)) {
 112                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 113                         __func__, dev->bus_id);
 114                 goto probe_failed;
 115         }
 116
 117         if (dev->bus->probe) {
 118                 ret = dev->bus->probe(dev);
 119                 if (ret)
 120                         goto probe_failed;
 121         } else if (drv->probe) {
 122                 ret = drv->probe(dev);
 123                 if (ret)
 124                         goto probe_failed;
 125         }
 126
 127         driver_bound(dev);
 128         ret = 1;
 129         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 130                  drv->bus->name, __func__, dev->bus_id, drv->name);
 131         goto done;
 132
 133 probe_failed:
 134         devres_release_all(dev);
 135         driver_sysfs_remove(dev);
 136         dev->driver = NULL;
 137
 138         if (ret != -ENODEV && ret != -ENXIO) {
 139                 /* driver matched but the probe failed */
 140                 printk(KERN_WARNING
 141                        "%s: probe of %s failed with error %d\n",
 142                        drv->name, dev->bus_id, ret);
 143         }
 144         /*
 145          * Ignore errors returned by ->probe so that the next driver can try
 146          * its luck.
 147          */
 148         ret = 0;
 149 done:
 150         atomic_dec(&probe_count);
 151         wake_up(&probe_waitqueue);
 152         return ret;
 153 }
 154
 155 /**
 156  * driver_probe_done
 157  * Determine if the probe sequence is finished or not.
 158  *
 159  * Should somehow figure out how to use a semaphore, not an atomic variable...
 160  */
 161 int driver_probe_done(void)
 162 {
 163         pr_debug("%s: probe_count = %d\n", __func__,
 164                  atomic_read(&probe_count));
 165         if (atomic_read(&probe_count))
 166                 return -EBUSY;
 167         return 0;
 168 }
 169
 170 /**
 171  * driver_probe_device - attempt to bind device & driver together
 172  * @drv: driver to bind a device to
 173  * @dev: device to try to bind to the driver
 174  *
 175  * First, we call the bus's match function, if one present, which should
 176  * compare the device IDs the driver supports with the device IDs of the
 177  * device. Note we don't do this ourselves because we don't know the
 178  * format of the ID structures, nor what is to be considered a match and
 179  * what is not.
 180  *
 181  * This function returns 1 if a match is found, -ENODEV if the device is
 182  * not registered, and 0 otherwise.
 183  *
 184  * This function must be called with @dev->sem held.  When called for a
 185  * USB interface, @dev->parent->sem must be held as well.
 186  */
 187 int driver_probe_device(struct device_driver *drv, struct device *dev)
 188 {
 189         int ret = 0;
 190
 191         if (!device_is_registered(dev))
 192                 return -ENODEV;
 193         if (drv->bus->match && !drv->bus->match(dev, drv))
 194                 goto done;
 195
 196         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 197                  drv->bus->name, __func__, dev->bus_id, drv->name);
 198
 199         ret = really_probe(dev, drv);
 200
 201 done:
 202         return ret;
 203 }
 204
 205 static int __device_attach(struct device_driver *drv, void *data)
 206 {
 207         struct device *dev = data;
 208         return driver_probe_device(drv, dev);
 209 }
 210
 211 /**
 212  * device_attach - try to attach device to a driver.
 213  * @dev: device.
 214  *
 215  * Walk the list of drivers that the bus has and call
 216  * driver_probe_device() for each pair. If a compatible
 217  * pair is found, break out and return.
 218  *
 219  * Returns 1 if the device was bound to a driver;
 220  * 0 if no matching device was found;
 221  * -ENODEV if the device is not registered.
 222  *
 223  * When called for a USB interface, @dev->parent->sem must be held.
 224  */
 225 int device_attach(struct device *dev)
 226 {
 227         int ret = 0;
 228
 229         down(&dev->sem);
 230         if (dev->driver) {
 231                 ret = device_bind_driver(dev);
 232                 if (ret == 0)
 233                         ret = 1;
 234                 else {
 235                         dev->driver = NULL;
 236                         ret = 0;
 237                 }
 238         } else {
 239                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
 240         }
 241         up(&dev->sem);
 242         return ret;
 243 }
 244 EXPORT_SYMBOL_GPL(device_attach);
 245
 246 static int __driver_attach(struct device *dev, void *data)
 247 {
 248         struct device_driver *drv = data;
 249
 250         /*
 251          * Lock device and try to bind to it. We drop the error
 252          * here and always return 0, because we need to keep trying
 253          * to bind to devices and some drivers will return an error
 254          * simply if it didn't support the device.
 255          *
 256          * driver_probe_device() will spit a warning if there
 257          * is an error.
 258          */
 259
 260         if (drv->bus->match && !drv->bus->match(dev, drv))
 261                 return 0;
 262
 263         if (dev->parent)        /* Needed for USB */
 264                 down(&dev->parent->sem);
 265         down(&dev->sem);
 266         if (!dev->driver)
 267                 driver_probe_device(drv, dev);
 268         up(&dev->sem);
 269         if (dev->parent)
 270                 up(&dev->parent->sem);
 271
 272         return 0;
 273 }
 274
 275 /**
 276  * driver_attach - try to bind driver to devices.
 277  * @drv: driver.
 278  *
 279  * Walk the list of devices that the bus has on it and try to
 280  * match the driver with each one.  If driver_probe_device()
 281  * returns 0 and the @dev->driver is set, we've found a
 282  * compatible pair.
 283  */
 284 int driver_attach(struct device_driver *drv)
 285 {
 286         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 287 }
 288 EXPORT_SYMBOL_GPL(driver_attach);
 289
 290 /*
 291  * __device_release_driver() must be called with @dev->sem held.
 292  * When called for a USB interface, @dev->parent->sem must be held as well.
 293  */
 294 static void __device_release_driver(struct device *dev)
 295 {
 296         struct device_driver *drv;
 297
 298         drv = dev->driver;
 299         if (drv) {
 300                 driver_sysfs_remove(dev);
 301                 sysfs_remove_link(&dev->kobj, "driver");
 302
 303                 if (dev->bus)
 304                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 305                                                      BUS_NOTIFY_UNBIND_DRIVER,
 306                                                      dev);
 307
 308                 if (dev->bus && dev->bus->remove)
 309                         dev->bus->remove(dev);
 310                 else if (drv->remove)
 311                         drv->remove(dev);
 312                 devres_release_all(dev);
 313                 dev->driver = NULL;
 314                 klist_remove(&dev->knode_driver);
 315         }
 316 }
 317
 318 /**
 319  * device_release_driver - manually detach device from driver.
 320  * @dev: device.
 321  *
 322  * Manually detach device from driver.
 323  * When called for a USB interface, @dev->parent->sem must be held.
 324  */
 325 void device_release_driver(struct device *dev)
 326 {
 327         /*
 328          * If anyone calls device_release_driver() recursively from
 329          * within their ->remove callback for the same device, they
 330          * will deadlock right here.
 331          */
 332         down(&dev->sem);
 333         __device_release_driver(dev);
 334         up(&dev->sem);
 335 }
 336 EXPORT_SYMBOL_GPL(device_release_driver);
 337
 338 /**
 339  * driver_detach - detach driver from all devices it controls.
 340  * @drv: driver.
 341  */
 342 void driver_detach(struct device_driver *drv)
 343 {
 344         struct device *dev;
 345
 346         for (;;) {
 347                 spin_lock(&drv->p->klist_devices.k_lock);
 348                 if (list_empty(&drv->p->klist_devices.k_list)) {
 349                         spin_unlock(&drv->p->klist_devices.k_lock);
 350                         break;
 351                 }
 352                 dev = list_entry(drv->p->klist_devices.k_list.prev,
 353                                 struct device, knode_driver.n_node);
 354                 get_device(dev);
 355                 spin_unlock(&drv->p->klist_devices.k_lock);
 356
 357                 if (dev->parent)        /* Needed for USB */
 358                         down(&dev->parent->sem);
 359                 down(&dev->sem);
 360                 if (dev->driver == drv)
 361                         __device_release_driver(dev);
 362                 up(&dev->sem);
 363                 if (dev->parent)
 364                         up(&dev->parent->sem);
 365                 put_device(dev);
 366         }
 367 }