driver core: don't fail attaching the device if it cannot be bound
[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  *
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 static atomic_t probe_count = ATOMIC_INIT(0);
98 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
99
100 static int really_probe(struct device *dev, struct device_driver *drv)
101 {
102         int ret = 0;
103
104         atomic_inc(&probe_count);
105         pr_debug("%s: Probing driver %s with device %s\n",
106                  drv->bus->name, drv->name, dev->bus_id);
107         WARN_ON(!list_empty(&dev->devres_head));
108
109         dev->driver = drv;
110         if (driver_sysfs_add(dev)) {
111                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
112                         __FUNCTION__, dev->bus_id);
113                 goto probe_failed;
114         }
115
116         if (dev->bus->probe) {
117                 ret = dev->bus->probe(dev);
118                 if (ret)
119                         goto probe_failed;
120         } else if (drv->probe) {
121                 ret = drv->probe(dev);
122                 if (ret)
123                         goto probe_failed;
124         }
125
126         driver_bound(dev);
127         ret = 1;
128         pr_debug("%s: Bound Device %s to Driver %s\n",
129                  drv->bus->name, dev->bus_id, drv->name);
130         goto done;
131
132 probe_failed:
133         devres_release_all(dev);
134         driver_sysfs_remove(dev);
135         dev->driver = NULL;
136
137         if (ret != -ENODEV && ret != -ENXIO) {
138                 /* driver matched but the probe failed */
139                 printk(KERN_WARNING
140                        "%s: probe of %s failed with error %d\n",
141                        drv->name, dev->bus_id, ret);
142         }
143         /*
144          * Ignore errors returned by ->probe so that the next driver can try
145          * its luck.
146          */
147         ret = 0;
148 done:
149         atomic_dec(&probe_count);
150         wake_up(&probe_waitqueue);
151         return ret;
152 }
153
154 /**
155  * driver_probe_done
156  * Determine if the probe sequence is finished or not.
157  *
158  * Should somehow figure out how to use a semaphore, not an atomic variable...
159  */
160 int driver_probe_done(void)
161 {
162         pr_debug("%s: probe_count = %d\n", __FUNCTION__,
163                  atomic_read(&probe_count));
164         if (atomic_read(&probe_count))
165                 return -EBUSY;
166         return 0;
167 }
168
169 /**
170  * driver_probe_device - attempt to bind device & driver together
171  * @drv: driver to bind a device to
172  * @dev: device to try to bind to the driver
173  *
174  * First, we call the bus's match function, if one present, which should
175  * compare the device IDs the driver supports with the device IDs of the
176  * device. Note we don't do this ourselves because we don't know the
177  * format of the ID structures, nor what is to be considered a match and
178  * what is not.
179  *
180  * This function returns 1 if a match is found, -ENODEV if the device is
181  * not registered, and 0 otherwise.
182  *
183  * This function must be called with @dev->sem held.  When called for a
184  * USB interface, @dev->parent->sem must be held as well.
185  */
186 int driver_probe_device(struct device_driver * drv, struct device * dev)
187 {
188         int ret = 0;
189
190         if (!device_is_registered(dev))
191                 return -ENODEV;
192         if (drv->bus->match && !drv->bus->match(dev, drv))
193                 goto done;
194
195         pr_debug("%s: Matched Device %s with Driver %s\n",
196                  drv->bus->name, dev->bus_id, drv->name);
197
198         ret = really_probe(dev, drv);
199
200 done:
201         return ret;
202 }
203
204 static int __device_attach(struct device_driver * drv, void * data)
205 {
206         struct device * dev = data;
207         return driver_probe_device(drv, dev);
208 }
209
210 static int device_probe_drivers(void *data)
211 {
212         struct device *dev = data;
213         int ret = 0;
214
215         if (dev->bus) {
216                 down(&dev->sem);
217                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
218                 up(&dev->sem);
219         }
220         return ret;
221 }
222
223 /**
224  *      device_attach - try to attach device to a driver.
225  *      @dev:   device.
226  *
227  *      Walk the list of drivers that the bus has and call
228  *      driver_probe_device() for each pair. If a compatible
229  *      pair is found, break out and return. If the bus specifies
230  *      multithreaded probing, walking the list of drivers is done
231  *      on a probing thread.
232  *
233  *      Returns 1 if the device was bound to a driver;
234  *      0 if no matching device was found or multithreaded probing is done;
235  *      -ENODEV if the device is not registered.
236  *
237  *      When called for a USB interface, @dev->parent->sem must be held.
238  */
239 int device_attach(struct device * dev)
240 {
241         int ret = 0;
242         struct task_struct *probe_task = ERR_PTR(-ENOMEM);
243
244         down(&dev->sem);
245         if (dev->driver) {
246                 ret = device_bind_driver(dev);
247                 if (ret == 0)
248                         ret = 1;
249                 else {
250                         dev->driver = NULL;
251                         ret = 0;
252                 }
253         } else {
254                 if (dev->bus->multithread_probe)
255                         probe_task = kthread_run(device_probe_drivers, dev,
256                                                  "probe-%s", dev->bus_id);
257                 if(IS_ERR(probe_task))
258                         ret = bus_for_each_drv(dev->bus, NULL, dev,
259                                                __device_attach);
260         }
261         up(&dev->sem);
262         return ret;
263 }
264
265 static int __driver_attach(struct device * dev, void * data)
266 {
267         struct device_driver * drv = data;
268
269         /*
270          * Lock device and try to bind to it. We drop the error
271          * here and always return 0, because we need to keep trying
272          * to bind to devices and some drivers will return an error
273          * simply if it didn't support the device.
274          *
275          * driver_probe_device() will spit a warning if there
276          * is an error.
277          */
278
279         if (dev->parent)        /* Needed for USB */
280                 down(&dev->parent->sem);
281         down(&dev->sem);
282         if (!dev->driver)
283                 driver_probe_device(drv, dev);
284         up(&dev->sem);
285         if (dev->parent)
286                 up(&dev->parent->sem);
287
288         return 0;
289 }
290
291 /**
292  *      driver_attach - try to bind driver to devices.
293  *      @drv:   driver.
294  *
295  *      Walk the list of devices that the bus has on it and try to
296  *      match the driver with each one.  If driver_probe_device()
297  *      returns 0 and the @dev->driver is set, we've found a
298  *      compatible pair.
299  */
300 int driver_attach(struct device_driver * drv)
301 {
302         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
303 }
304
305 /**
306  *      device_release_driver - manually detach device from driver.
307  *      @dev:   device.
308  *
309  *      Manually detach device from driver.
310  *
311  *      __device_release_driver() must be called with @dev->sem held.
312  *      When called for a USB interface, @dev->parent->sem must be held
313  *      as well.
314  */
315
316 static void __device_release_driver(struct device * dev)
317 {
318         struct device_driver * drv;
319
320         drv = dev->driver;
321         if (drv) {
322                 get_driver(drv);
323                 driver_sysfs_remove(dev);
324                 sysfs_remove_link(&dev->kobj, "driver");
325                 klist_remove(&dev->knode_driver);
326
327                 if (dev->bus)
328                         blocking_notifier_call_chain(&dev->bus->bus_notifier,
329                                                      BUS_NOTIFY_UNBIND_DRIVER,
330                                                      dev);
331
332                 if (dev->bus && dev->bus->remove)
333                         dev->bus->remove(dev);
334                 else if (drv->remove)
335                         drv->remove(dev);
336                 devres_release_all(dev);
337                 dev->driver = NULL;
338                 put_driver(drv);
339         }
340 }
341
342 void device_release_driver(struct device * dev)
343 {
344         /*
345          * If anyone calls device_release_driver() recursively from
346          * within their ->remove callback for the same device, they
347          * will deadlock right here.
348          */
349         down(&dev->sem);
350         __device_release_driver(dev);
351         up(&dev->sem);
352 }
353
354
355 /**
356  * driver_detach - detach driver from all devices it controls.
357  * @drv: driver.
358  */
359 void driver_detach(struct device_driver * drv)
360 {
361         struct device * dev;
362
363         for (;;) {
364                 spin_lock(&drv->klist_devices.k_lock);
365                 if (list_empty(&drv->klist_devices.k_list)) {
366                         spin_unlock(&drv->klist_devices.k_lock);
367                         break;
368                 }
369                 dev = list_entry(drv->klist_devices.k_list.prev,
370                                 struct device, knode_driver.n_node);
371                 get_device(dev);
372                 spin_unlock(&drv->klist_devices.k_lock);
373
374                 if (dev->parent)        /* Needed for USB */
375                         down(&dev->parent->sem);
376                 down(&dev->sem);
377                 if (dev->driver == drv)
378                         __device_release_driver(dev);
379                 up(&dev->sem);
380                 if (dev->parent)
381                         up(&dev->parent->sem);
382                 put_device(dev);
383         }
384 }
385
386 #ifdef CONFIG_PCI_MULTITHREAD_PROBE
387 static int __init wait_for_probes(void)
388 {
389         DEFINE_WAIT(wait);
390
391         printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__,
392                         atomic_read(&probe_count));
393         if (!atomic_read(&probe_count))
394                 return 0;
395         while (atomic_read(&probe_count)) {
396                 prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE);
397                 if (atomic_read(&probe_count))
398                         schedule();
399         }
400         finish_wait(&probe_waitqueue, &wait);
401         return 0;
402 }
403
404 core_initcall_sync(wait_for_probes);
405 postcore_initcall_sync(wait_for_probes);
406 arch_initcall_sync(wait_for_probes);
407 subsys_initcall_sync(wait_for_probes);
408 fs_initcall_sync(wait_for_probes);
409 device_initcall_sync(wait_for_probes);
410 late_initcall_sync(wait_for_probes);
411 #endif
412
413 EXPORT_SYMBOL_GPL(device_bind_driver);
414 EXPORT_SYMBOL_GPL(device_release_driver);
415 EXPORT_SYMBOL_GPL(device_attach);
416 EXPORT_SYMBOL_GPL(driver_attach);
417