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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         driver_bound(dev);
  90         return driver_sysfs_add(dev);
  91 }
  92
  93 struct stupid_thread_structure {
  94         struct device_driver *drv;
  95         struct device *dev;
  96 };
  97
  98 static atomic_t probe_count = ATOMIC_INIT(0);
  99 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 100
 101 static int really_probe(void *void_data)
 102 {
 103         struct stupid_thread_structure *data = void_data;
 104         struct device_driver *drv = data->drv;
 105         struct device *dev = data->dev;
 106         int ret = 0;
 107
 108         atomic_inc(&probe_count);
 109         pr_debug("%s: Probing driver %s with device %s\n",
 110                  drv->bus->name, drv->name, dev->bus_id);
 111
 112         dev->driver = drv;
 113         if (driver_sysfs_add(dev)) {
 114                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 115                         __FUNCTION__, dev->bus_id);
 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("%s: Bound Device %s to Driver %s\n",
 132                  drv->bus->name, dev->bus_id, drv->name);
 133         goto done;
 134
 135 probe_failed:
 136         driver_sysfs_remove(dev);
 137         dev->driver = NULL;
 138
 139         if (ret == -ENODEV || ret == -ENXIO) {
 140                 /* Driver matched, but didn't support device
 141                  * or device not found.
 142                  * Not an error; keep going.
 143                  */
 144                 ret = 0;
 145         } else {
 146                 /* driver matched but the probe failed */
 147                 printk(KERN_WARNING
 148                        "%s: probe of %s failed with error %d\n",
 149                        drv->name, dev->bus_id, ret);
 150         }
 151 done:
 152         kfree(data);
 153         atomic_dec(&probe_count);
 154         wake_up(&probe_waitqueue);
 155         return ret;
 156 }
 157
 158 /**
 159  * driver_probe_done
 160  * Determine if the probe sequence is finished or not.
 161  *
 162  * Should somehow figure out how to use a semaphore, not an atomic variable...
 163  */
 164 int driver_probe_done(void)
 165 {
 166         pr_debug("%s: probe_count = %d\n", __FUNCTION__,
 167                  atomic_read(&probe_count));
 168         if (atomic_read(&probe_count))
 169                 return -EBUSY;
 170         return 0;
 171 }
 172
 173 /**
 174  * driver_probe_device - attempt to bind device & driver together
 175  * @drv: driver to bind a device to
 176  * @dev: device to try to bind to the driver
 177  *
 178  * First, we call the bus's match function, if one present, which should
 179  * compare the device IDs the driver supports with the device IDs of the
 180  * device. Note we don't do this ourselves because we don't know the
 181  * format of the ID structures, nor what is to be considered a match and
 182  * what is not.
 183  *
 184  * This function returns 1 if a match is found, an error if one occurs
 185  * (that is not -ENODEV or -ENXIO), and 0 otherwise.
 186  *
 187  * This function must be called with @dev->sem held.  When called for a
 188  * USB interface, @dev->parent->sem must be held as well.
 189  */
 190 int driver_probe_device(struct device_driver * drv, struct device * dev)
 191 {
 192         struct stupid_thread_structure *data;
 193         struct task_struct *probe_task;
 194         int ret = 0;
 195
 196         if (!device_is_registered(dev))
 197                 return -ENODEV;
 198         if (drv->bus->match && !drv->bus->match(dev, drv))
 199                 goto done;
 200
 201         pr_debug("%s: Matched Device %s with Driver %s\n",
 202                  drv->bus->name, dev->bus_id, drv->name);
 203
 204         data = kmalloc(sizeof(*data), GFP_KERNEL);
 205         if (!data)
 206                 return -ENOMEM;
 207         data->drv = drv;
 208         data->dev = dev;
 209
 210         if (drv->multithread_probe) {
 211                 probe_task = kthread_run(really_probe, data,
 212                                          "probe-%s", dev->bus_id);
 213                 if (IS_ERR(probe_task))
 214                         ret = really_probe(data);
 215         } else
 216                 ret = really_probe(data);
 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; error code otherwise.
 238  *
 239  *      When called for a USB interface, @dev->parent->sem must be held.
 240  */
 241 int device_attach(struct device * dev)
 242 {
 243         int ret = 0;
 244
 245         down(&dev->sem);
 246         if (dev->driver) {
 247                 ret = device_bind_driver(dev);
 248                 if (ret == 0)
 249                         ret = 1;
 250         } else
 251                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
 252         up(&dev->sem);
 253         return ret;
 254 }
 255
 256 static int __driver_attach(struct device * dev, void * data)
 257 {
 258         struct device_driver * drv = data;
 259
 260         /*
 261          * Lock device and try to bind to it. We drop the error
 262          * here and always return 0, because we need to keep trying
 263          * to bind to devices and some drivers will return an error
 264          * simply if it didn't support the device.
 265          *
 266          * driver_probe_device() will spit a warning if there
 267          * is an error.
 268          */
 269
 270         if (dev->parent)        /* Needed for USB */
 271                 down(&dev->parent->sem);
 272         down(&dev->sem);
 273         if (!dev->driver)
 274                 driver_probe_device(drv, dev);
 275         up(&dev->sem);
 276         if (dev->parent)
 277                 up(&dev->parent->sem);
 278
 279         return 0;
 280 }
 281
 282 /**
 283  *      driver_attach - try to bind driver to devices.
 284  *      @drv:   driver.
 285  *
 286  *      Walk the list of devices that the bus has on it and try to
 287  *      match the driver with each one.  If driver_probe_device()
 288  *      returns 0 and the @dev->driver is set, we've found a
 289  *      compatible pair.
 290  */
 291 int driver_attach(struct device_driver * drv)
 292 {
 293         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 294 }
 295
 296 /**
 297  *      device_release_driver - manually detach device from driver.
 298  *      @dev:   device.
 299  *
 300  *      Manually detach device from driver.
 301  *
 302  *      __device_release_driver() must be called with @dev->sem held.
 303  *      When called for a USB interface, @dev->parent->sem must be held
 304  *      as well.
 305  */
 306
 307 static void __device_release_driver(struct device * dev)
 308 {
 309         struct device_driver * drv;
 310
 311         drv = dev->driver;
 312         if (drv) {
 313                 get_driver(drv);
 314                 driver_sysfs_remove(dev);
 315                 sysfs_remove_link(&dev->kobj, "driver");
 316                 klist_remove(&dev->knode_driver);
 317
 318                 if (dev->bus)
 319                         blocking_notifier_call_chain(&dev->bus->bus_notifier,
 320                                                      BUS_NOTIFY_UNBIND_DRIVER,
 321                                                      dev);
 322
 323                 if (dev->bus && dev->bus->remove)
 324                         dev->bus->remove(dev);
 325                 else if (drv->remove)
 326                         drv->remove(dev);
 327                 dev->driver = NULL;
 328                 put_driver(drv);
 329         }
 330 }
 331
 332 void device_release_driver(struct device * dev)
 333 {
 334         /*
 335          * If anyone calls device_release_driver() recursively from
 336          * within their ->remove callback for the same device, they
 337          * will deadlock right here.
 338          */
 339         down(&dev->sem);
 340         __device_release_driver(dev);
 341         up(&dev->sem);
 342 }
 343
 344
 345 /**
 346  * driver_detach - detach driver from all devices it controls.
 347  * @drv: driver.
 348  */
 349 void driver_detach(struct device_driver * drv)
 350 {
 351         struct device * dev;
 352
 353         for (;;) {
 354                 spin_lock(&drv->klist_devices.k_lock);
 355                 if (list_empty(&drv->klist_devices.k_list)) {
 356                         spin_unlock(&drv->klist_devices.k_lock);
 357                         break;
 358                 }
 359                 dev = list_entry(drv->klist_devices.k_list.prev,
 360                                 struct device, knode_driver.n_node);
 361                 get_device(dev);
 362                 spin_unlock(&drv->klist_devices.k_lock);
 363
 364                 if (dev->parent)        /* Needed for USB */
 365                         down(&dev->parent->sem);
 366                 down(&dev->sem);
 367                 if (dev->driver == drv)
 368                         __device_release_driver(dev);
 369                 up(&dev->sem);
 370                 if (dev->parent)
 371                         up(&dev->parent->sem);
 372                 put_device(dev);
 373         }
 374 }
 375
 376 #ifdef CONFIG_PCI_MULTITHREAD_PROBE
 377 static int __init wait_for_probes(void)
 378 {
 379         DEFINE_WAIT(wait);
 380
 381         printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__,
 382                         atomic_read(&probe_count));
 383         if (!atomic_read(&probe_count))
 384                 return 0;
 385         while (atomic_read(&probe_count)) {
 386                 prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE);
 387                 if (atomic_read(&probe_count))
 388                         schedule();
 389         }
 390         finish_wait(&probe_waitqueue, &wait);
 391         return 0;
 392 }
 393
 394 core_initcall_sync(wait_for_probes);
 395 postcore_initcall_sync(wait_for_probes);
 396 arch_initcall_sync(wait_for_probes);
 397 subsys_initcall_sync(wait_for_probes);
 398 fs_initcall_sync(wait_for_probes);
 399 device_initcall_sync(wait_for_probes);
 400 late_initcall_sync(wait_for_probes);
 401 #endif
 402
 403 EXPORT_SYMBOL_GPL(device_bind_driver);
 404 EXPORT_SYMBOL_GPL(device_release_driver);
 405 EXPORT_SYMBOL_GPL(device_attach);
 406 EXPORT_SYMBOL_GPL(driver_attach);
 407