c89291f8a16bb09749664f9717c98c55a8176a18
[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         if (dev->bus)
44                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
45                                              BUS_NOTIFY_BOUND_DRIVER, dev);
46
47         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
48 }
49
50 static int driver_sysfs_add(struct device *dev)
51 {
52         int ret;
53
54         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
55                           kobject_name(&dev->kobj));
56         if (ret == 0) {
57                 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
58                                         "driver");
59                 if (ret)
60                         sysfs_remove_link(&dev->driver->p->kobj,
61                                         kobject_name(&dev->kobj));
62         }
63         return ret;
64 }
65
66 static void driver_sysfs_remove(struct device *dev)
67 {
68         struct device_driver *drv = dev->driver;
69
70         if (drv) {
71                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
72                 sysfs_remove_link(&dev->kobj, "driver");
73         }
74 }
75
76 /**
77  * device_bind_driver - bind a driver to one device.
78  * @dev: device.
79  *
80  * Allow manual attachment of a driver to a device.
81  * Caller must have already set @dev->driver.
82  *
83  * Note that this does not modify the bus reference count
84  * nor take the bus's rwsem. Please verify those are accounted
85  * for before calling this. (It is ok to call with no other effort
86  * from a driver's probe() method.)
87  *
88  * This function must be called with the device lock held.
89  */
90 int device_bind_driver(struct device *dev)
91 {
92         int ret;
93
94         ret = driver_sysfs_add(dev);
95         if (!ret)
96                 driver_bound(dev);
97         return ret;
98 }
99 EXPORT_SYMBOL_GPL(device_bind_driver);
100
101 static atomic_t probe_count = ATOMIC_INIT(0);
102 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
103
104 static int really_probe(struct device *dev, struct device_driver *drv)
105 {
106         int ret = 0;
107
108         atomic_inc(&probe_count);
109         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
110                  drv->bus->name, __func__, drv->name, dev_name(dev));
111         WARN_ON(!list_empty(&dev->devres_head));
112
113         dev->driver = drv;
114         if (driver_sysfs_add(dev)) {
115                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
116                         __func__, dev_name(dev));
117                 goto probe_failed;
118         }
119
120         if (dev->bus->probe) {
121                 ret = dev->bus->probe(dev);
122                 if (ret)
123                         goto probe_failed;
124         } else if (drv->probe) {
125                 ret = drv->probe(dev);
126                 if (ret)
127                         goto probe_failed;
128         }
129
130         driver_bound(dev);
131         ret = 1;
132         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
133                  drv->bus->name, __func__, dev_name(dev), drv->name);
134         goto done;
135
136 probe_failed:
137         devres_release_all(dev);
138         driver_sysfs_remove(dev);
139         dev->driver = NULL;
140
141         if (ret != -ENODEV && ret != -ENXIO) {
142                 /* driver matched but the probe failed */
143                 printk(KERN_WARNING
144                        "%s: probe of %s failed with error %d\n",
145                        drv->name, dev_name(dev), ret);
146         }
147         /*
148          * Ignore errors returned by ->probe so that the next driver can try
149          * its luck.
150          */
151         ret = 0;
152 done:
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", __func__,
167                  atomic_read(&probe_count));
168         if (atomic_read(&probe_count))
169                 return -EBUSY;
170         return 0;
171 }
172
173 /**
174  * wait_for_device_probe
175  * Wait for device probing to be completed.
176  */
177 void wait_for_device_probe(void)
178 {
179         /* wait for the known devices to complete their probing */
180         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
181         async_synchronize_full();
182 }
183 EXPORT_SYMBOL_GPL(wait_for_device_probe);
184
185 /**
186  * driver_probe_device - attempt to bind device & driver together
187  * @drv: driver to bind a device to
188  * @dev: device to try to bind to the driver
189  *
190  * This function returns -ENODEV if the device is not registered,
191  * 1 if the device is bound successfully and 0 otherwise.
192  *
193  * This function must be called with @dev lock held.  When called for a
194  * USB interface, @dev->parent lock must be held as well.
195  */
196 int driver_probe_device(struct device_driver *drv, struct device *dev)
197 {
198         int ret = 0;
199
200         if (!device_is_registered(dev))
201                 return -ENODEV;
202
203         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
204                  drv->bus->name, __func__, dev_name(dev), drv->name);
205
206         pm_runtime_get_noresume(dev);
207         pm_runtime_barrier(dev);
208         ret = really_probe(dev, drv);
209         pm_runtime_put_sync(dev);
210
211         return ret;
212 }
213
214 static int __device_attach(struct device_driver *drv, void *data)
215 {
216         struct device *dev = data;
217
218         if (!driver_match_device(drv, dev))
219                 return 0;
220
221         return driver_probe_device(drv, dev);
222 }
223
224 /**
225  * device_attach - try to attach device to a driver.
226  * @dev: device.
227  *
228  * Walk the list of drivers that the bus has and call
229  * driver_probe_device() for each pair. If a compatible
230  * pair is found, break out and return.
231  *
232  * Returns 1 if the device was bound to a driver;
233  * 0 if no matching driver was found;
234  * -ENODEV if the device is not registered.
235  *
236  * When called for a USB interface, @dev->parent lock must be held.
237  */
238 int device_attach(struct device *dev)
239 {
240         int ret = 0;
241
242         device_lock(dev);
243         if (dev->driver) {
244                 ret = device_bind_driver(dev);
245                 if (ret == 0)
246                         ret = 1;
247                 else {
248                         dev->driver = NULL;
249                         ret = 0;
250                 }
251         } else {
252                 pm_runtime_get_noresume(dev);
253                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
254                 pm_runtime_put_sync(dev);
255         }
256         device_unlock(dev);
257         return ret;
258 }
259 EXPORT_SYMBOL_GPL(device_attach);
260
261 static int __driver_attach(struct device *dev, void *data)
262 {
263         struct device_driver *drv = data;
264
265         /*
266          * Lock device and try to bind to it. We drop the error
267          * here and always return 0, because we need to keep trying
268          * to bind to devices and some drivers will return an error
269          * simply if it didn't support the device.
270          *
271          * driver_probe_device() will spit a warning if there
272          * is an error.
273          */
274
275         if (!driver_match_device(drv, dev))
276                 return 0;
277
278         if (dev->parent)        /* Needed for USB */
279                 device_lock(dev->parent);
280         device_lock(dev);
281         if (!dev->driver)
282                 driver_probe_device(drv, dev);
283         device_unlock(dev);
284         if (dev->parent)
285                 device_unlock(dev->parent);
286
287         return 0;
288 }
289
290 /**
291  * driver_attach - try to bind driver to devices.
292  * @drv: driver.
293  *
294  * Walk the list of devices that the bus has on it and try to
295  * match the driver with each one.  If driver_probe_device()
296  * returns 0 and the @dev->driver is set, we've found a
297  * compatible pair.
298  */
299 int driver_attach(struct device_driver *drv)
300 {
301         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
302 }
303 EXPORT_SYMBOL_GPL(driver_attach);
304
305 /*
306  * __device_release_driver() must be called with @dev lock held.
307  * When called for a USB interface, @dev->parent lock must be held as well.
308  */
309 static void __device_release_driver(struct device *dev)
310 {
311         struct device_driver *drv;
312
313         drv = dev->driver;
314         if (drv) {
315                 pm_runtime_get_noresume(dev);
316                 pm_runtime_barrier(dev);
317
318                 driver_sysfs_remove(dev);
319
320                 if (dev->bus)
321                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
322                                                      BUS_NOTIFY_UNBIND_DRIVER,
323                                                      dev);
324
325                 if (dev->bus && dev->bus->remove)
326                         dev->bus->remove(dev);
327                 else if (drv->remove)
328                         drv->remove(dev);
329                 devres_release_all(dev);
330                 dev->driver = NULL;
331                 klist_remove(&dev->p->knode_driver);
332                 if (dev->bus)
333                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
334                                                      BUS_NOTIFY_UNBOUND_DRIVER,
335                                                      dev);
336
337                 pm_runtime_put_sync(dev);
338         }
339 }
340
341 /**
342  * device_release_driver - manually detach device from driver.
343  * @dev: device.
344  *
345  * Manually detach device from driver.
346  * When called for a USB interface, @dev->parent lock must be held.
347  */
348 void device_release_driver(struct device *dev)
349 {
350         /*
351          * If anyone calls device_release_driver() recursively from
352          * within their ->remove callback for the same device, they
353          * will deadlock right here.
354          */
355         device_lock(dev);
356         __device_release_driver(dev);
357         device_unlock(dev);
358 }
359 EXPORT_SYMBOL_GPL(device_release_driver);
360
361 /**
362  * driver_detach - detach driver from all devices it controls.
363  * @drv: driver.
364  */
365 void driver_detach(struct device_driver *drv)
366 {
367         struct device_private *dev_prv;
368         struct device *dev;
369
370         for (;;) {
371                 spin_lock(&drv->p->klist_devices.k_lock);
372                 if (list_empty(&drv->p->klist_devices.k_list)) {
373                         spin_unlock(&drv->p->klist_devices.k_lock);
374                         break;
375                 }
376                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
377                                      struct device_private,
378                                      knode_driver.n_node);
379                 dev = dev_prv->device;
380                 get_device(dev);
381                 spin_unlock(&drv->p->klist_devices.k_lock);
382
383                 if (dev->parent)        /* Needed for USB */
384                         device_lock(dev->parent);
385                 device_lock(dev);
386                 if (dev->driver == drv)
387                         __device_release_driver(dev);
388                 device_unlock(dev);
389                 if (dev->parent)
390                         device_unlock(dev->parent);
391                 put_device(dev);
392         }
393 }
394
395 /*
396  * These exports can't be _GPL due to .h files using this within them, and it
397  * might break something that was previously working...
398  */
399 void *dev_get_drvdata(const struct device *dev)
400 {
401         if (dev && dev->p)
402                 return dev->p->driver_data;
403         return NULL;
404 }
405 EXPORT_SYMBOL(dev_get_drvdata);
406
407 void dev_set_drvdata(struct device *dev, void *data)
408 {
409         int error;
410
411         if (!dev)
412                 return;
413         if (!dev->p) {
414                 error = device_private_init(dev);
415                 if (error)
416                         return;
417         }
418         dev->p->driver_data = data;
419 }
420 EXPORT_SYMBOL(dev_set_drvdata);