SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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  *
  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 struct stupid_thread_structure {
  98         struct device_driver *drv;
  99         struct device *dev;
 100 };
 101
 102 static atomic_t probe_count = ATOMIC_INIT(0);
 103 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 104
 105 static int really_probe(void *void_data)
 106 {
 107         struct stupid_thread_structure *data = void_data;
 108         struct device_driver *drv = data->drv;
 109         struct device *dev = data->dev;
 110         int ret = 0;
 111
 112         atomic_inc(&probe_count);
 113         pr_debug("%s: Probing driver %s with device %s\n",
 114                  drv->bus->name, drv->name, dev->bus_id);
 115
 116         dev->driver = drv;
 117         if (driver_sysfs_add(dev)) {
 118                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 119                         __FUNCTION__, dev->bus_id);
 120                 goto probe_failed;
 121         }
 122
 123         if (dev->bus->probe) {
 124                 ret = dev->bus->probe(dev);
 125                 if (ret)
 126                         goto probe_failed;
 127         } else if (drv->probe) {
 128                 ret = drv->probe(dev);
 129                 if (ret)
 130                         goto probe_failed;
 131         }
 132
 133         driver_bound(dev);
 134         ret = 1;
 135         pr_debug("%s: Bound Device %s to Driver %s\n",
 136                  drv->bus->name, dev->bus_id, drv->name);
 137         goto done;
 138
 139 probe_failed:
 140         driver_sysfs_remove(dev);
 141         dev->driver = NULL;
 142
 143         if (ret != -ENODEV && ret != -ENXIO) {
 144                 /* driver matched but the probe failed */
 145                 printk(KERN_WARNING
 146                        "%s: probe of %s failed with error %d\n",
 147                        drv->name, dev->bus_id, ret);
 148         }
 149         /*
 150          * Ignore errors returned by ->probe so that the next driver can try
 151          * its luck.
 152          */
 153         ret = 0;
 154 done:
 155         kfree(data);
 156         atomic_dec(&probe_count);
 157         wake_up(&probe_waitqueue);
 158         return ret;
 159 }
 160
 161 /**
 162  * driver_probe_done
 163  * Determine if the probe sequence is finished or not.
 164  *
 165  * Should somehow figure out how to use a semaphore, not an atomic variable...
 166  */
 167 int driver_probe_done(void)
 168 {
 169         pr_debug("%s: probe_count = %d\n", __FUNCTION__,
 170                  atomic_read(&probe_count));
 171         if (atomic_read(&probe_count))
 172                 return -EBUSY;
 173         return 0;
 174 }
 175
 176 /**
 177  * driver_probe_device - attempt to bind device & driver together
 178  * @drv: driver to bind a device to
 179  * @dev: device to try to bind to the driver
 180  *
 181  * First, we call the bus's match function, if one present, which should
 182  * compare the device IDs the driver supports with the device IDs of the
 183  * device. Note we don't do this ourselves because we don't know the
 184  * format of the ID structures, nor what is to be considered a match and
 185  * what is not.
 186  *
 187  * This function returns 1 if a match is found, an error if one occurs
 188  * (that is not -ENODEV or -ENXIO), and 0 otherwise.
 189  *
 190  * This function must be called with @dev->sem held.  When called for a
 191  * USB interface, @dev->parent->sem must be held as well.
 192  */
 193 int driver_probe_device(struct device_driver * drv, struct device * dev)
 194 {
 195         struct stupid_thread_structure *data;
 196         struct task_struct *probe_task;
 197         int ret = 0;
 198
 199         if (!device_is_registered(dev))
 200                 return -ENODEV;
 201         if (drv->bus->match && !drv->bus->match(dev, drv))
 202                 goto done;
 203
 204         pr_debug("%s: Matched Device %s with Driver %s\n",
 205                  drv->bus->name, dev->bus_id, drv->name);
 206
 207         data = kmalloc(sizeof(*data), GFP_KERNEL);
 208         if (!data)
 209                 return -ENOMEM;
 210         data->drv = drv;
 211         data->dev = dev;
 212
 213         if (drv->multithread_probe) {
 214                 probe_task = kthread_run(really_probe, data,
 215                                          "probe-%s", dev->bus_id);
 216                 if (IS_ERR(probe_task))
 217                         ret = really_probe(data);
 218         } else
 219                 ret = really_probe(data);
 220
 221 done:
 222         return ret;
 223 }
 224
 225 static int __device_attach(struct device_driver * drv, void * data)
 226 {
 227         struct device * dev = data;
 228         return driver_probe_device(drv, dev);
 229 }
 230
 231 /**
 232  *      device_attach - try to attach device to a driver.
 233  *      @dev:   device.
 234  *
 235  *      Walk the list of drivers that the bus has and call
 236  *      driver_probe_device() for each pair. If a compatible
 237  *      pair is found, break out and return.
 238  *
 239  *      Returns 1 if the device was bound to a driver;
 240  *      0 if no matching device was found; error code otherwise.
 241  *
 242  *      When called for a USB interface, @dev->parent->sem must be held.
 243  */
 244 int device_attach(struct device * dev)
 245 {
 246         int ret = 0;
 247
 248         down(&dev->sem);
 249         if (dev->driver) {
 250                 ret = device_bind_driver(dev);
 251                 if (ret == 0)
 252                         ret = 1;
 253         } else
 254                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
 255         up(&dev->sem);
 256         return ret;
 257 }
 258
 259 static int __driver_attach(struct device * dev, void * data)
 260 {
 261         struct device_driver * drv = data;
 262
 263         /*
 264          * Lock device and try to bind to it. We drop the error
 265          * here and always return 0, because we need to keep trying
 266          * to bind to devices and some drivers will return an error
 267          * simply if it didn't support the device.
 268          *
 269          * driver_probe_device() will spit a warning if there
 270          * is an error.
 271          */
 272
 273         if (dev->parent)        /* Needed for USB */
 274                 down(&dev->parent->sem);
 275         down(&dev->sem);
 276         if (!dev->driver)
 277                 driver_probe_device(drv, dev);
 278         up(&dev->sem);
 279         if (dev->parent)
 280                 up(&dev->parent->sem);
 281
 282         return 0;
 283 }
 284
 285 /**
 286  *      driver_attach - try to bind driver to devices.
 287  *      @drv:   driver.
 288  *
 289  *      Walk the list of devices that the bus has on it and try to
 290  *      match the driver with each one.  If driver_probe_device()
 291  *      returns 0 and the @dev->driver is set, we've found a
 292  *      compatible pair.
 293  */
 294 int driver_attach(struct device_driver * drv)
 295 {
 296         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 297 }
 298
 299 /**
 300  *      device_release_driver - manually detach device from driver.
 301  *      @dev:   device.
 302  *
 303  *      Manually detach device from driver.
 304  *
 305  *      __device_release_driver() must be called with @dev->sem held.
 306  *      When called for a USB interface, @dev->parent->sem must be held
 307  *      as well.
 308  */
 309
 310 static void __device_release_driver(struct device * dev)
 311 {
 312         struct device_driver * drv;
 313
 314         drv = dev->driver;
 315         if (drv) {
 316                 get_driver(drv);
 317                 driver_sysfs_remove(dev);
 318                 sysfs_remove_link(&dev->kobj, "driver");
 319                 klist_remove(&dev->knode_driver);
 320
 321                 if (dev->bus)
 322                         blocking_notifier_call_chain(&dev->bus->bus_notifier,
 323                                                      BUS_NOTIFY_UNBIND_DRIVER,
 324                                                      dev);
 325
 326                 if (dev->bus && dev->bus->remove)
 327                         dev->bus->remove(dev);
 328                 else if (drv->remove)
 329                         drv->remove(dev);
 330                 dev->driver = NULL;
 331                 put_driver(drv);
 332         }
 333 }
 334
 335 void device_release_driver(struct device * dev)
 336 {
 337         /*
 338          * If anyone calls device_release_driver() recursively from
 339          * within their ->remove callback for the same device, they
 340          * will deadlock right here.
 341          */
 342         down(&dev->sem);
 343         __device_release_driver(dev);
 344         up(&dev->sem);
 345 }
 346
 347
 348 /**
 349  * driver_detach - detach driver from all devices it controls.
 350  * @drv: driver.
 351  */
 352 void driver_detach(struct device_driver * drv)
 353 {
 354         struct device * dev;
 355
 356         for (;;) {
 357                 spin_lock(&drv->klist_devices.k_lock);
 358                 if (list_empty(&drv->klist_devices.k_list)) {
 359                         spin_unlock(&drv->klist_devices.k_lock);
 360                         break;
 361                 }
 362                 dev = list_entry(drv->klist_devices.k_list.prev,
 363                                 struct device, knode_driver.n_node);
 364                 get_device(dev);
 365                 spin_unlock(&drv->klist_devices.k_lock);
 366
 367                 if (dev->parent)        /* Needed for USB */
 368                         down(&dev->parent->sem);
 369                 down(&dev->sem);
 370                 if (dev->driver == drv)
 371                         __device_release_driver(dev);
 372                 up(&dev->sem);
 373                 if (dev->parent)
 374                         up(&dev->parent->sem);
 375                 put_device(dev);
 376         }
 377 }
 378
 379 #ifdef CONFIG_PCI_MULTITHREAD_PROBE
 380 static int __init wait_for_probes(void)
 381 {
 382         DEFINE_WAIT(wait);
 383
 384         printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__,
 385                         atomic_read(&probe_count));
 386         if (!atomic_read(&probe_count))
 387                 return 0;
 388         while (atomic_read(&probe_count)) {
 389                 prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE);
 390                 if (atomic_read(&probe_count))
 391                         schedule();
 392         }
 393         finish_wait(&probe_waitqueue, &wait);
 394         return 0;
 395 }
 396
 397 core_initcall_sync(wait_for_probes);
 398 postcore_initcall_sync(wait_for_probes);
 399 arch_initcall_sync(wait_for_probes);
 400 subsys_initcall_sync(wait_for_probes);
 401 fs_initcall_sync(wait_for_probes);
 402 device_initcall_sync(wait_for_probes);
 403 late_initcall_sync(wait_for_probes);
 404 #endif
 405
 406 EXPORT_SYMBOL_GPL(device_bind_driver);
 407 EXPORT_SYMBOL_GPL(device_release_driver);
 408 EXPORT_SYMBOL_GPL(device_attach);
 409 EXPORT_SYMBOL_GPL(driver_attach);
 410