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