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   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  *
  15  *      This file is released under the GPLv2
  16  */
  17
  18 #include <linux/device.h>
  19 #include <linux/module.h>
  20 #include <linux/kthread.h>
  21 #include <linux/wait.h>
  22
  23 #include "base.h"
  24 #include "power/power.h"
  25
  26 #define to_drv(node) container_of(node, struct device_driver, kobj.entry)
  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                         __FUNCTION__, kobject_name(&dev->kobj));
  34                 return;
  35         }
  36
  37         pr_debug("bound device '%s' to driver '%s'\n",
  38                  dev->bus_id, dev->driver->name);
  39
  40         if (dev->bus)
  41                 blocking_notifier_call_chain(&dev->bus->bus_notifier,
  42                                              BUS_NOTIFY_BOUND_DRIVER, dev);
  43
  44         klist_add_tail(&dev->knode_driver, &dev->driver->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->kobj, &dev->kobj,
  52                           kobject_name(&dev->kobj));
  53         if (ret == 0) {
  54                 ret = sysfs_create_link(&dev->kobj, &dev->driver->kobj,
  55                                         "driver");
  56                 if (ret)
  57                         sysfs_remove_link(&dev->driver->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->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
  97 static atomic_t probe_count = ATOMIC_INIT(0);
  98 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
  99
 100 static int really_probe(struct device *dev, struct device_driver *drv)
 101 {
 102         int ret = 0;
 103
 104         atomic_inc(&probe_count);
 105         pr_debug("%s: Probing driver %s with device %s\n",
 106                  drv->bus->name, drv->name, dev->bus_id);
 107         WARN_ON(!list_empty(&dev->devres_head));
 108
 109         dev->driver = drv;
 110         if (driver_sysfs_add(dev)) {
 111                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 112                         __FUNCTION__, dev->bus_id);
 113                 goto probe_failed;
 114         }
 115
 116         if (dev->bus->probe) {
 117                 ret = dev->bus->probe(dev);
 118                 if (ret)
 119                         goto probe_failed;
 120         } else if (drv->probe) {
 121                 ret = drv->probe(dev);
 122                 if (ret)
 123                         goto probe_failed;
 124         }
 125
 126         driver_bound(dev);
 127         ret = 1;
 128         pr_debug("%s: Bound Device %s to Driver %s\n",
 129                  drv->bus->name, dev->bus_id, drv->name);
 130         goto done;
 131
 132 probe_failed:
 133         devres_release_all(dev);
 134         driver_sysfs_remove(dev);
 135         dev->driver = NULL;
 136
 137         if (ret != -ENODEV && ret != -ENXIO) {
 138                 /* driver matched but the probe failed */
 139                 printk(KERN_WARNING
 140                        "%s: probe of %s failed with error %d\n",
 141                        drv->name, dev->bus_id, ret);
 142         }
 143         /*
 144          * Ignore errors returned by ->probe so that the next driver can try
 145          * its luck.
 146          */
 147         ret = 0;
 148 done:
 149         atomic_dec(&probe_count);
 150         wake_up(&probe_waitqueue);
 151         return ret;
 152 }
 153
 154 /**
 155  * driver_probe_done
 156  * Determine if the probe sequence is finished or not.
 157  *
 158  * Should somehow figure out how to use a semaphore, not an atomic variable...
 159  */
 160 int driver_probe_done(void)
 161 {
 162         pr_debug("%s: probe_count = %d\n", __FUNCTION__,
 163                  atomic_read(&probe_count));
 164         if (atomic_read(&probe_count))
 165                 return -EBUSY;
 166         return 0;
 167 }
 168
 169 /**
 170  * driver_probe_device - attempt to bind device & driver together
 171  * @drv: driver to bind a device to
 172  * @dev: device to try to bind to the driver
 173  *
 174  * First, we call the bus's match function, if one present, which should
 175  * compare the device IDs the driver supports with the device IDs of the
 176  * device. Note we don't do this ourselves because we don't know the
 177  * format of the ID structures, nor what is to be considered a match and
 178  * what is not.
 179  *
 180  * This function returns 1 if a match is found, -ENODEV if the device is
 181  * not registered, and 0 otherwise.
 182  *
 183  * This function must be called with @dev->sem held.  When called for a
 184  * USB interface, @dev->parent->sem must be held as well.
 185  */
 186 int driver_probe_device(struct device_driver * drv, struct device * dev)
 187 {
 188         int ret = 0;
 189
 190         if (!device_is_registered(dev))
 191                 return -ENODEV;
 192         if (drv->bus->match && !drv->bus->match(dev, drv))
 193                 goto done;
 194
 195         pr_debug("%s: Matched Device %s with Driver %s\n",
 196                  drv->bus->name, dev->bus_id, drv->name);
 197
 198         ret = really_probe(dev, drv);
 199
 200 done:
 201         return ret;
 202 }
 203
 204 static int __device_attach(struct device_driver * drv, void * data)
 205 {
 206         struct device * dev = data;
 207         return driver_probe_device(drv, dev);
 208 }
 209
 210 static int device_probe_drivers(void *data)
 211 {
 212         struct device *dev = data;
 213         int ret = 0;
 214
 215         if (dev->bus) {
 216                 down(&dev->sem);
 217                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
 218                 up(&dev->sem);
 219         }
 220         return ret;
 221 }
 222
 223 /**
 224  *      device_attach - try to attach device to a driver.
 225  *      @dev:   device.
 226  *
 227  *      Walk the list of drivers that the bus has and call
 228  *      driver_probe_device() for each pair. If a compatible
 229  *      pair is found, break out and return. If the bus specifies
 230  *      multithreaded probing, walking the list of drivers is done
 231  *      on a probing thread.
 232  *
 233  *      Returns 1 if the device was bound to a driver;
 234  *      0 if no matching device was found or multithreaded probing is done;
 235  *      -ENODEV if the device is not registered.
 236  *
 237  *      When called for a USB interface, @dev->parent->sem must be held.
 238  */
 239 int device_attach(struct device * dev)
 240 {
 241         int ret = 0;
 242         struct task_struct *probe_task = ERR_PTR(-ENOMEM);
 243
 244         down(&dev->sem);
 245         if (dev->driver) {
 246                 ret = device_bind_driver(dev);
 247                 if (ret == 0)
 248                         ret = 1;
 249                 else {
 250                         dev->driver = NULL;
 251                         ret = 0;
 252                 }
 253         } else {
 254                 if (dev->bus->multithread_probe)
 255                         probe_task = kthread_run(device_probe_drivers, dev,
 256                                                  "probe-%s", dev->bus_id);
 257                 if(IS_ERR(probe_task))
 258                         ret = bus_for_each_drv(dev->bus, NULL, dev,
 259                                                __device_attach);
 260         }
 261         up(&dev->sem);
 262         return ret;
 263 }
 264
 265 static int __driver_attach(struct device * dev, void * data)
 266 {
 267         struct device_driver * drv = data;
 268
 269         /*
 270          * Lock device and try to bind to it. We drop the error
 271          * here and always return 0, because we need to keep trying
 272          * to bind to devices and some drivers will return an error
 273          * simply if it didn't support the device.
 274          *
 275          * driver_probe_device() will spit a warning if there
 276          * is an error.
 277          */
 278
 279         if (dev->parent)        /* Needed for USB */
 280                 down(&dev->parent->sem);
 281         down(&dev->sem);
 282         if (!dev->driver)
 283                 driver_probe_device(drv, dev);
 284         up(&dev->sem);
 285         if (dev->parent)
 286                 up(&dev->parent->sem);
 287
 288         return 0;
 289 }
 290
 291 /**
 292  *      driver_attach - try to bind driver to devices.
 293  *      @drv:   driver.
 294  *
 295  *      Walk the list of devices that the bus has on it and try to
 296  *      match the driver with each one.  If driver_probe_device()
 297  *      returns 0 and the @dev->driver is set, we've found a
 298  *      compatible pair.
 299  */
 300 int driver_attach(struct device_driver * drv)
 301 {
 302         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 303 }
 304
 305 /**
 306  *      device_release_driver - manually detach device from driver.
 307  *      @dev:   device.
 308  *
 309  *      Manually detach device from driver.
 310  *
 311  *      __device_release_driver() must be called with @dev->sem held.
 312  *      When called for a USB interface, @dev->parent->sem must be held
 313  *      as well.
 314  */
 315
 316 static void __device_release_driver(struct device * dev)
 317 {
 318         struct device_driver * drv;
 319
 320         drv = dev->driver;
 321         if (drv) {
 322                 get_driver(drv);
 323                 driver_sysfs_remove(dev);
 324                 sysfs_remove_link(&dev->kobj, "driver");
 325                 klist_remove(&dev->knode_driver);
 326
 327                 if (dev->bus)
 328                         blocking_notifier_call_chain(&dev->bus->bus_notifier,
 329                                                      BUS_NOTIFY_UNBIND_DRIVER,
 330                                                      dev);
 331
 332                 if (dev->bus && dev->bus->remove)
 333                         dev->bus->remove(dev);
 334                 else if (drv->remove)
 335                         drv->remove(dev);
 336                 devres_release_all(dev);
 337                 dev->driver = NULL;
 338                 put_driver(drv);
 339         }
 340 }
 341
 342 void device_release_driver(struct device * dev)
 343 {
 344         /*
 345          * If anyone calls device_release_driver() recursively from
 346          * within their ->remove callback for the same device, they
 347          * will deadlock right here.
 348          */
 349         down(&dev->sem);
 350         __device_release_driver(dev);
 351         up(&dev->sem);
 352 }
 353
 354
 355 /**
 356  * driver_detach - detach driver from all devices it controls.
 357  * @drv: driver.
 358  */
 359 void driver_detach(struct device_driver * drv)
 360 {
 361         struct device * dev;
 362
 363         for (;;) {
 364                 spin_lock(&drv->klist_devices.k_lock);
 365                 if (list_empty(&drv->klist_devices.k_list)) {
 366                         spin_unlock(&drv->klist_devices.k_lock);
 367                         break;
 368                 }
 369                 dev = list_entry(drv->klist_devices.k_list.prev,
 370                                 struct device, knode_driver.n_node);
 371                 get_device(dev);
 372                 spin_unlock(&drv->klist_devices.k_lock);
 373
 374                 if (dev->parent)        /* Needed for USB */
 375                         down(&dev->parent->sem);
 376                 down(&dev->sem);
 377                 if (dev->driver == drv)
 378                         __device_release_driver(dev);
 379                 up(&dev->sem);
 380                 if (dev->parent)
 381                         up(&dev->parent->sem);
 382                 put_device(dev);
 383         }
 384 }
 385
 386 #ifdef CONFIG_PCI_MULTITHREAD_PROBE
 387 static int __init wait_for_probes(void)
 388 {
 389         DEFINE_WAIT(wait);
 390
 391         printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__,
 392                         atomic_read(&probe_count));
 393         if (!atomic_read(&probe_count))
 394                 return 0;
 395         while (atomic_read(&probe_count)) {
 396                 prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE);
 397                 if (atomic_read(&probe_count))
 398                         schedule();
 399         }
 400         finish_wait(&probe_waitqueue, &wait);
 401         return 0;
 402 }
 403
 404 core_initcall_sync(wait_for_probes);
 405 postcore_initcall_sync(wait_for_probes);
 406 arch_initcall_sync(wait_for_probes);
 407 subsys_initcall_sync(wait_for_probes);
 408 fs_initcall_sync(wait_for_probes);
 409 device_initcall_sync(wait_for_probes);
 410 late_initcall_sync(wait_for_probes);
 411 #endif
 412
 413 EXPORT_SYMBOL_GPL(device_bind_driver);
 414 EXPORT_SYMBOL_GPL(device_release_driver);
 415 EXPORT_SYMBOL_GPL(device_attach);
 416 EXPORT_SYMBOL_GPL(driver_attach);
 417