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 /**
  30  *      device_bind_driver - bind a driver to one device.
  31  *      @dev:   device.
  32  *
  33  *      Allow manual attachment of a driver to a device.
  34  *      Caller must have already set @dev->driver.
  35  *
  36  *      Note that this does not modify the bus reference count
  37  *      nor take the bus's rwsem. Please verify those are accounted
  38  *      for before calling this. (It is ok to call with no other effort
  39  *      from a driver's probe() method.)
  40  *
  41  *      This function must be called with @dev->sem held.
  42  */
  43 int device_bind_driver(struct device *dev)
  44 {
  45         int ret;
  46
  47         if (klist_node_attached(&dev->knode_driver)) {
  48                 printk(KERN_WARNING "%s: device %s already bound\n",
  49                         __FUNCTION__, kobject_name(&dev->kobj));
  50                 return 0;
  51         }
  52
  53         pr_debug("bound device '%s' to driver '%s'\n",
  54                  dev->bus_id, dev->driver->name);
  55         klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices);
  56         ret = sysfs_create_link(&dev->driver->kobj, &dev->kobj,
  57                           kobject_name(&dev->kobj));
  58         if (ret == 0) {
  59                 ret = sysfs_create_link(&dev->kobj, &dev->driver->kobj,
  60                                         "driver");
  61                 if (ret)
  62                         sysfs_remove_link(&dev->driver->kobj,
  63                                         kobject_name(&dev->kobj));
  64         }
  65         return ret;
  66 }
  67
  68 struct stupid_thread_structure {
  69         struct device_driver *drv;
  70         struct device *dev;
  71 };
  72
  73 static atomic_t probe_count = ATOMIC_INIT(0);
  74 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
  75
  76 static int really_probe(void *void_data)
  77 {
  78         struct stupid_thread_structure *data = void_data;
  79         struct device_driver *drv = data->drv;
  80         struct device *dev = data->dev;
  81         int ret = 0;
  82
  83         atomic_inc(&probe_count);
  84         pr_debug("%s: Probing driver %s with device %s\n",
  85                  drv->bus->name, drv->name, dev->bus_id);
  86
  87         dev->driver = drv;
  88         if (dev->bus->probe) {
  89                 ret = dev->bus->probe(dev);
  90                 if (ret) {
  91                         dev->driver = NULL;
  92                         goto probe_failed;
  93                 }
  94         } else if (drv->probe) {
  95                 ret = drv->probe(dev);
  96                 if (ret) {
  97                         dev->driver = NULL;
  98                         goto probe_failed;
  99                 }
 100         }
 101         if (device_bind_driver(dev)) {
 102                 printk(KERN_ERR "%s: device_bind_driver(%s) failed\n",
 103                         __FUNCTION__, dev->bus_id);
 104                 /* How does undo a ->probe?  We're screwed. */
 105         }
 106         ret = 1;
 107         pr_debug("%s: Bound Device %s to Driver %s\n",
 108                  drv->bus->name, dev->bus_id, drv->name);
 109         goto done;
 110
 111 probe_failed:
 112         if (ret == -ENODEV || ret == -ENXIO) {
 113                 /* Driver matched, but didn't support device
 114                  * or device not found.
 115                  * Not an error; keep going.
 116                  */
 117                 ret = 0;
 118         } else {
 119                 /* driver matched but the probe failed */
 120                 printk(KERN_WARNING
 121                        "%s: probe of %s failed with error %d\n",
 122                        drv->name, dev->bus_id, ret);
 123         }
 124 done:
 125         kfree(data);
 126         atomic_dec(&probe_count);
 127         wake_up(&probe_waitqueue);
 128         return ret;
 129 }
 130
 131 /**
 132  * driver_probe_done
 133  * Determine if the probe sequence is finished or not.
 134  *
 135  * Should somehow figure out how to use a semaphore, not an atomic variable...
 136  */
 137 int driver_probe_done(void)
 138 {
 139         pr_debug("%s: probe_count = %d\n", __FUNCTION__,
 140                  atomic_read(&probe_count));
 141         if (atomic_read(&probe_count))
 142                 return -EBUSY;
 143         return 0;
 144 }
 145
 146 /**
 147  * driver_probe_device - attempt to bind device & driver together
 148  * @drv: driver to bind a device to
 149  * @dev: device to try to bind to the driver
 150  *
 151  * First, we call the bus's match function, if one present, which should
 152  * compare the device IDs the driver supports with the device IDs of the
 153  * device. Note we don't do this ourselves because we don't know the
 154  * format of the ID structures, nor what is to be considered a match and
 155  * what is not.
 156  *
 157  * This function returns 1 if a match is found, an error if one occurs
 158  * (that is not -ENODEV or -ENXIO), and 0 otherwise.
 159  *
 160  * This function must be called with @dev->sem held.  When called for a
 161  * USB interface, @dev->parent->sem must be held as well.
 162  */
 163 int driver_probe_device(struct device_driver * drv, struct device * dev)
 164 {
 165         struct stupid_thread_structure *data;
 166         struct task_struct *probe_task;
 167         int ret = 0;
 168
 169         if (!device_is_registered(dev))
 170                 return -ENODEV;
 171         if (drv->bus->match && !drv->bus->match(dev, drv))
 172                 goto done;
 173
 174         pr_debug("%s: Matched Device %s with Driver %s\n",
 175                  drv->bus->name, dev->bus_id, drv->name);
 176
 177         data = kmalloc(sizeof(*data), GFP_KERNEL);
 178         if (!data)
 179                 return -ENOMEM;
 180         data->drv = drv;
 181         data->dev = dev;
 182
 183         if (drv->multithread_probe) {
 184                 probe_task = kthread_run(really_probe, data,
 185                                          "probe-%s", dev->bus_id);
 186                 if (IS_ERR(probe_task))
 187                         ret = really_probe(data);
 188         } else
 189                 ret = really_probe(data);
 190
 191 done:
 192         return ret;
 193 }
 194
 195 static int __device_attach(struct device_driver * drv, void * data)
 196 {
 197         struct device * dev = data;
 198         return driver_probe_device(drv, dev);
 199 }
 200
 201 /**
 202  *      device_attach - try to attach device to a driver.
 203  *      @dev:   device.
 204  *
 205  *      Walk the list of drivers that the bus has and call
 206  *      driver_probe_device() for each pair. If a compatible
 207  *      pair is found, break out and return.
 208  *
 209  *      Returns 1 if the device was bound to a driver;
 210  *      0 if no matching device was found; error code otherwise.
 211  *
 212  *      When called for a USB interface, @dev->parent->sem must be held.
 213  */
 214 int device_attach(struct device * dev)
 215 {
 216         int ret = 0;
 217
 218         down(&dev->sem);
 219         if (dev->driver) {
 220                 ret = device_bind_driver(dev);
 221                 if (ret == 0)
 222                         ret = 1;
 223         } else
 224                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
 225         up(&dev->sem);
 226         return ret;
 227 }
 228
 229 static int __driver_attach(struct device * dev, void * data)
 230 {
 231         struct device_driver * drv = data;
 232
 233         /*
 234          * Lock device and try to bind to it. We drop the error
 235          * here and always return 0, because we need to keep trying
 236          * to bind to devices and some drivers will return an error
 237          * simply if it didn't support the device.
 238          *
 239          * driver_probe_device() will spit a warning if there
 240          * is an error.
 241          */
 242
 243         if (dev->parent)        /* Needed for USB */
 244                 down(&dev->parent->sem);
 245         down(&dev->sem);
 246         if (!dev->driver)
 247                 driver_probe_device(drv, dev);
 248         up(&dev->sem);
 249         if (dev->parent)
 250                 up(&dev->parent->sem);
 251
 252         return 0;
 253 }
 254
 255 /**
 256  *      driver_attach - try to bind driver to devices.
 257  *      @drv:   driver.
 258  *
 259  *      Walk the list of devices that the bus has on it and try to
 260  *      match the driver with each one.  If driver_probe_device()
 261  *      returns 0 and the @dev->driver is set, we've found a
 262  *      compatible pair.
 263  */
 264 int driver_attach(struct device_driver * drv)
 265 {
 266         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 267 }
 268
 269 /**
 270  *      device_release_driver - manually detach device from driver.
 271  *      @dev:   device.
 272  *
 273  *      Manually detach device from driver.
 274  *
 275  *      __device_release_driver() must be called with @dev->sem held.
 276  *      When called for a USB interface, @dev->parent->sem must be held
 277  *      as well.
 278  */
 279
 280 static void __device_release_driver(struct device * dev)
 281 {
 282         struct device_driver * drv;
 283
 284         drv = dev->driver;
 285         if (drv) {
 286                 get_driver(drv);
 287                 sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
 288                 sysfs_remove_link(&dev->kobj, "driver");
 289                 klist_remove(&dev->knode_driver);
 290
 291                 if (dev->bus && dev->bus->remove)
 292                         dev->bus->remove(dev);
 293                 else if (drv->remove)
 294                         drv->remove(dev);
 295                 dev->driver = NULL;
 296                 put_driver(drv);
 297         }
 298 }
 299
 300 void device_release_driver(struct device * dev)
 301 {
 302         /*
 303          * If anyone calls device_release_driver() recursively from
 304          * within their ->remove callback for the same device, they
 305          * will deadlock right here.
 306          */
 307         down(&dev->sem);
 308         __device_release_driver(dev);
 309         up(&dev->sem);
 310 }
 311
 312
 313 /**
 314  * driver_detach - detach driver from all devices it controls.
 315  * @drv: driver.
 316  */
 317 void driver_detach(struct device_driver * drv)
 318 {
 319         struct device * dev;
 320
 321         for (;;) {
 322                 spin_lock(&drv->klist_devices.k_lock);
 323                 if (list_empty(&drv->klist_devices.k_list)) {
 324                         spin_unlock(&drv->klist_devices.k_lock);
 325                         break;
 326                 }
 327                 dev = list_entry(drv->klist_devices.k_list.prev,
 328                                 struct device, knode_driver.n_node);
 329                 get_device(dev);
 330                 spin_unlock(&drv->klist_devices.k_lock);
 331
 332                 if (dev->parent)        /* Needed for USB */
 333                         down(&dev->parent->sem);
 334                 down(&dev->sem);
 335                 if (dev->driver == drv)
 336                         __device_release_driver(dev);
 337                 up(&dev->sem);
 338                 if (dev->parent)
 339                         up(&dev->parent->sem);
 340                 put_device(dev);
 341         }
 342 }
 343
 344 #ifdef CONFIG_PCI_MULTITHREAD_PROBE
 345 static int __init wait_for_probes(void)
 346 {
 347         DEFINE_WAIT(wait);
 348
 349         printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__,
 350                         atomic_read(&probe_count));
 351         if (!atomic_read(&probe_count))
 352                 return 0;
 353         while (atomic_read(&probe_count)) {
 354                 prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE);
 355                 if (atomic_read(&probe_count))
 356                         schedule();
 357         }
 358         finish_wait(&probe_waitqueue, &wait);
 359         return 0;
 360 }
 361
 362 core_initcall_sync(wait_for_probes);
 363 postcore_initcall_sync(wait_for_probes);
 364 arch_initcall_sync(wait_for_probes);
 365 subsys_initcall_sync(wait_for_probes);
 366 fs_initcall_sync(wait_for_probes);
 367 device_initcall_sync(wait_for_probes);
 368 late_initcall_sync(wait_for_probes);
 369 #endif
 370
 371 EXPORT_SYMBOL_GPL(device_bind_driver);
 372 EXPORT_SYMBOL_GPL(device_release_driver);
 373 EXPORT_SYMBOL_GPL(device_attach);
 374 EXPORT_SYMBOL_GPL(driver_attach);
 375