dma-buf: add support for kernel cpu access
[linux-2.6.git] / 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) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
15  * Copyright (c) 2007-2009 Novell Inc.
16  *
17  * This file is released under the GPLv2
18  */
19
20 #include <linux/device.h>
21 #include <linux/delay.h>
22 #include <linux/module.h>
23 #include <linux/kthread.h>
24 #include <linux/wait.h>
25 #include <linux/async.h>
26 #include <linux/pm_runtime.h>
27
28 #include "base.h"
29 #include "power/power.h"
30
31
32 static void driver_bound(struct device *dev)
33 {
34         if (klist_node_attached(&dev->p->knode_driver)) {
35                 printk(KERN_WARNING "%s: device %s already bound\n",
36                         __func__, kobject_name(&dev->kobj));
37                 return;
38         }
39
40         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev_name(dev),
41                  __func__, dev->driver->name);
42
43         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
44
45         if (dev->bus)
46                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
47                                              BUS_NOTIFY_BOUND_DRIVER, dev);
48 }
49
50 static int driver_sysfs_add(struct device *dev)
51 {
52         int ret;
53
54         if (dev->bus)
55                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
56                                              BUS_NOTIFY_BIND_DRIVER, dev);
57
58         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
59                           kobject_name(&dev->kobj));
60         if (ret == 0) {
61                 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
62                                         "driver");
63                 if (ret)
64                         sysfs_remove_link(&dev->driver->p->kobj,
65                                         kobject_name(&dev->kobj));
66         }
67         return ret;
68 }
69
70 static void driver_sysfs_remove(struct device *dev)
71 {
72         struct device_driver *drv = dev->driver;
73
74         if (drv) {
75                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
76                 sysfs_remove_link(&dev->kobj, "driver");
77         }
78 }
79
80 /**
81  * device_bind_driver - bind a driver to one device.
82  * @dev: device.
83  *
84  * Allow manual attachment of a driver to a device.
85  * Caller must have already set @dev->driver.
86  *
87  * Note that this does not modify the bus reference count
88  * nor take the bus's rwsem. Please verify those are accounted
89  * for before calling this. (It is ok to call with no other effort
90  * from a driver's probe() method.)
91  *
92  * This function must be called with the device lock held.
93  */
94 int device_bind_driver(struct device *dev)
95 {
96         int ret;
97
98         ret = driver_sysfs_add(dev);
99         if (!ret)
100                 driver_bound(dev);
101         return ret;
102 }
103 EXPORT_SYMBOL_GPL(device_bind_driver);
104
105 static atomic_t probe_count = ATOMIC_INIT(0);
106 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
107
108 static int really_probe(struct device *dev, struct device_driver *drv)
109 {
110         int ret = 0;
111
112         atomic_inc(&probe_count);
113         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
114                  drv->bus->name, __func__, drv->name, dev_name(dev));
115         WARN_ON(!list_empty(&dev->devres_head));
116
117         dev->driver = drv;
118         if (driver_sysfs_add(dev)) {
119                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
120                         __func__, dev_name(dev));
121                 goto probe_failed;
122         }
123
124         if (dev->bus->probe) {
125                 ret = dev->bus->probe(dev);
126                 if (ret)
127                         goto probe_failed;
128         } else if (drv->probe) {
129                 ret = drv->probe(dev);
130                 if (ret)
131                         goto probe_failed;
132         }
133
134         driver_bound(dev);
135         ret = 1;
136         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
137                  drv->bus->name, __func__, dev_name(dev), drv->name);
138         goto done;
139
140 probe_failed:
141         devres_release_all(dev);
142         driver_sysfs_remove(dev);
143         dev->driver = NULL;
144
145         if (ret != -ENODEV && ret != -ENXIO) {
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_name(dev), ret);
150         } else {
151                 pr_debug("%s: probe of %s rejects match %d\n",
152                        drv->name, dev_name(dev), ret);
153         }
154         /*
155          * Ignore errors returned by ->probe so that the next driver can try
156          * its luck.
157          */
158         ret = 0;
159 done:
160         atomic_dec(&probe_count);
161         wake_up(&probe_waitqueue);
162         return ret;
163 }
164
165 /**
166  * driver_probe_done
167  * Determine if the probe sequence is finished or not.
168  *
169  * Should somehow figure out how to use a semaphore, not an atomic variable...
170  */
171 int driver_probe_done(void)
172 {
173         pr_debug("%s: probe_count = %d\n", __func__,
174                  atomic_read(&probe_count));
175         if (atomic_read(&probe_count))
176                 return -EBUSY;
177         return 0;
178 }
179
180 /**
181  * wait_for_device_probe
182  * Wait for device probing to be completed.
183  */
184 void wait_for_device_probe(void)
185 {
186         /* wait for the known devices to complete their probing */
187         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
188         async_synchronize_full();
189 }
190 EXPORT_SYMBOL_GPL(wait_for_device_probe);
191
192 /**
193  * driver_probe_device - attempt to bind device & driver together
194  * @drv: driver to bind a device to
195  * @dev: device to try to bind to the driver
196  *
197  * This function returns -ENODEV if the device is not registered,
198  * 1 if the device is bound successfully and 0 otherwise.
199  *
200  * This function must be called with @dev lock held.  When called for a
201  * USB interface, @dev->parent lock must be held as well.
202  */
203 int driver_probe_device(struct device_driver *drv, struct device *dev)
204 {
205         int ret = 0;
206
207         if (!device_is_registered(dev))
208                 return -ENODEV;
209
210         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
211                  drv->bus->name, __func__, dev_name(dev), drv->name);
212
213         pm_runtime_get_noresume(dev);
214         pm_runtime_barrier(dev);
215         ret = really_probe(dev, drv);
216         pm_runtime_put_sync(dev);
217
218         return ret;
219 }
220
221 static int __device_attach(struct device_driver *drv, void *data)
222 {
223         struct device *dev = data;
224
225         if (!driver_match_device(drv, dev))
226                 return 0;
227
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 driver was found;
241  * -ENODEV if the device is not registered.
242  *
243  * When called for a USB interface, @dev->parent lock must be held.
244  */
245 int device_attach(struct device *dev)
246 {
247         int ret = 0;
248
249         device_lock(dev);
250         if (dev->driver) {
251                 if (klist_node_attached(&dev->p->knode_driver)) {
252                         ret = 1;
253                         goto out_unlock;
254                 }
255                 ret = device_bind_driver(dev);
256                 if (ret == 0)
257                         ret = 1;
258                 else {
259                         dev->driver = NULL;
260                         ret = 0;
261                 }
262         } else {
263                 pm_runtime_get_noresume(dev);
264                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
265                 pm_runtime_put_sync(dev);
266         }
267 out_unlock:
268         device_unlock(dev);
269         return ret;
270 }
271 EXPORT_SYMBOL_GPL(device_attach);
272
273 static int __driver_attach(struct device *dev, void *data)
274 {
275         struct device_driver *drv = data;
276
277         /*
278          * Lock device and try to bind to it. We drop the error
279          * here and always return 0, because we need to keep trying
280          * to bind to devices and some drivers will return an error
281          * simply if it didn't support the device.
282          *
283          * driver_probe_device() will spit a warning if there
284          * is an error.
285          */
286
287         if (!driver_match_device(drv, dev))
288                 return 0;
289
290         if (dev->parent)        /* Needed for USB */
291                 device_lock(dev->parent);
292         device_lock(dev);
293         if (!dev->driver)
294                 driver_probe_device(drv, dev);
295         device_unlock(dev);
296         if (dev->parent)
297                 device_unlock(dev->parent);
298
299         return 0;
300 }
301
302 /**
303  * driver_attach - try to bind driver to devices.
304  * @drv: driver.
305  *
306  * Walk the list of devices that the bus has on it and try to
307  * match the driver with each one.  If driver_probe_device()
308  * returns 0 and the @dev->driver is set, we've found a
309  * compatible pair.
310  */
311 int driver_attach(struct device_driver *drv)
312 {
313         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
314 }
315 EXPORT_SYMBOL_GPL(driver_attach);
316
317 /*
318  * __device_release_driver() must be called with @dev lock held.
319  * When called for a USB interface, @dev->parent lock must be held as well.
320  */
321 static void __device_release_driver(struct device *dev)
322 {
323         struct device_driver *drv;
324
325         drv = dev->driver;
326         if (drv) {
327                 pm_runtime_get_sync(dev);
328
329                 driver_sysfs_remove(dev);
330
331                 if (dev->bus)
332                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
333                                                      BUS_NOTIFY_UNBIND_DRIVER,
334                                                      dev);
335
336                 pm_runtime_put_sync(dev);
337
338                 if (dev->bus && dev->bus->remove)
339                         dev->bus->remove(dev);
340                 else if (drv->remove)
341                         drv->remove(dev);
342                 devres_release_all(dev);
343                 dev->driver = NULL;
344                 klist_remove(&dev->p->knode_driver);
345                 if (dev->bus)
346                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
347                                                      BUS_NOTIFY_UNBOUND_DRIVER,
348                                                      dev);
349
350         }
351 }
352
353 /**
354  * device_release_driver - manually detach device from driver.
355  * @dev: device.
356  *
357  * Manually detach device from driver.
358  * When called for a USB interface, @dev->parent lock must be held.
359  */
360 void device_release_driver(struct device *dev)
361 {
362         /*
363          * If anyone calls device_release_driver() recursively from
364          * within their ->remove callback for the same device, they
365          * will deadlock right here.
366          */
367         device_lock(dev);
368         __device_release_driver(dev);
369         device_unlock(dev);
370 }
371 EXPORT_SYMBOL_GPL(device_release_driver);
372
373 /**
374  * driver_detach - detach driver from all devices it controls.
375  * @drv: driver.
376  */
377 void driver_detach(struct device_driver *drv)
378 {
379         struct device_private *dev_prv;
380         struct device *dev;
381
382         for (;;) {
383                 spin_lock(&drv->p->klist_devices.k_lock);
384                 if (list_empty(&drv->p->klist_devices.k_list)) {
385                         spin_unlock(&drv->p->klist_devices.k_lock);
386                         break;
387                 }
388                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
389                                      struct device_private,
390                                      knode_driver.n_node);
391                 dev = dev_prv->device;
392                 get_device(dev);
393                 spin_unlock(&drv->p->klist_devices.k_lock);
394
395                 if (dev->parent)        /* Needed for USB */
396                         device_lock(dev->parent);
397                 device_lock(dev);
398                 if (dev->driver == drv)
399                         __device_release_driver(dev);
400                 device_unlock(dev);
401                 if (dev->parent)
402                         device_unlock(dev->parent);
403                 put_device(dev);
404         }
405 }
406
407 /*
408  * These exports can't be _GPL due to .h files using this within them, and it
409  * might break something that was previously working...
410  */
411 void *dev_get_drvdata(const struct device *dev)
412 {
413         if (dev && dev->p)
414                 return dev->p->driver_data;
415         return NULL;
416 }
417 EXPORT_SYMBOL(dev_get_drvdata);
418
419 int dev_set_drvdata(struct device *dev, void *data)
420 {
421         int error;
422
423         if (!dev->p) {
424                 error = device_private_init(dev);
425                 if (error)
426                         return error;
427         }
428         dev->p->driver_data = data;
429         return 0;
430 }
431 EXPORT_SYMBOL(dev_set_drvdata);