Driver core: add notification of bus events
[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 /**
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
56         if (dev->bus)
57                 blocking_notifier_call_chain(&dev->bus->bus_notifier,
58                                              BUS_NOTIFY_BOUND_DRIVER, dev);
59
60         klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices);
61         ret = sysfs_create_link(&dev->driver->kobj, &dev->kobj,
62                           kobject_name(&dev->kobj));
63         if (ret == 0) {
64                 ret = sysfs_create_link(&dev->kobj, &dev->driver->kobj,
65                                         "driver");
66                 if (ret)
67                         sysfs_remove_link(&dev->driver->kobj,
68                                         kobject_name(&dev->kobj));
69         }
70         return ret;
71 }
72
73 struct stupid_thread_structure {
74         struct device_driver *drv;
75         struct device *dev;
76 };
77
78 static atomic_t probe_count = ATOMIC_INIT(0);
79 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
80
81 static int really_probe(void *void_data)
82 {
83         struct stupid_thread_structure *data = void_data;
84         struct device_driver *drv = data->drv;
85         struct device *dev = data->dev;
86         int ret = 0;
87
88         atomic_inc(&probe_count);
89         pr_debug("%s: Probing driver %s with device %s\n",
90                  drv->bus->name, drv->name, dev->bus_id);
91
92         dev->driver = drv;
93         if (dev->bus->probe) {
94                 ret = dev->bus->probe(dev);
95                 if (ret) {
96                         dev->driver = NULL;
97                         goto probe_failed;
98                 }
99         } else if (drv->probe) {
100                 ret = drv->probe(dev);
101                 if (ret) {
102                         dev->driver = NULL;
103                         goto probe_failed;
104                 }
105         }
106         if (device_bind_driver(dev)) {
107                 printk(KERN_ERR "%s: device_bind_driver(%s) failed\n",
108                         __FUNCTION__, dev->bus_id);
109                 /* How does undo a ->probe?  We're screwed. */
110         }
111         ret = 1;
112         pr_debug("%s: Bound Device %s to Driver %s\n",
113                  drv->bus->name, dev->bus_id, drv->name);
114         goto done;
115
116 probe_failed:
117         if (ret == -ENODEV || ret == -ENXIO) {
118                 /* Driver matched, but didn't support device
119                  * or device not found.
120                  * Not an error; keep going.
121                  */
122                 ret = 0;
123         } else {
124                 /* driver matched but the probe failed */
125                 printk(KERN_WARNING
126                        "%s: probe of %s failed with error %d\n",
127                        drv->name, dev->bus_id, ret);
128         }
129 done:
130         kfree(data);
131         atomic_dec(&probe_count);
132         wake_up(&probe_waitqueue);
133         return ret;
134 }
135
136 /**
137  * driver_probe_done
138  * Determine if the probe sequence is finished or not.
139  *
140  * Should somehow figure out how to use a semaphore, not an atomic variable...
141  */
142 int driver_probe_done(void)
143 {
144         pr_debug("%s: probe_count = %d\n", __FUNCTION__,
145                  atomic_read(&probe_count));
146         if (atomic_read(&probe_count))
147                 return -EBUSY;
148         return 0;
149 }
150
151 /**
152  * driver_probe_device - attempt to bind device & driver together
153  * @drv: driver to bind a device to
154  * @dev: device to try to bind to the driver
155  *
156  * First, we call the bus's match function, if one present, which should
157  * compare the device IDs the driver supports with the device IDs of the
158  * device. Note we don't do this ourselves because we don't know the
159  * format of the ID structures, nor what is to be considered a match and
160  * what is not.
161  *
162  * This function returns 1 if a match is found, an error if one occurs
163  * (that is not -ENODEV or -ENXIO), and 0 otherwise.
164  *
165  * This function must be called with @dev->sem held.  When called for a
166  * USB interface, @dev->parent->sem must be held as well.
167  */
168 int driver_probe_device(struct device_driver * drv, struct device * dev)
169 {
170         struct stupid_thread_structure *data;
171         struct task_struct *probe_task;
172         int ret = 0;
173
174         if (!device_is_registered(dev))
175                 return -ENODEV;
176         if (drv->bus->match && !drv->bus->match(dev, drv))
177                 goto done;
178
179         pr_debug("%s: Matched Device %s with Driver %s\n",
180                  drv->bus->name, dev->bus_id, drv->name);
181
182         data = kmalloc(sizeof(*data), GFP_KERNEL);
183         if (!data)
184                 return -ENOMEM;
185         data->drv = drv;
186         data->dev = dev;
187
188         if (drv->multithread_probe) {
189                 probe_task = kthread_run(really_probe, data,
190                                          "probe-%s", dev->bus_id);
191                 if (IS_ERR(probe_task))
192                         ret = really_probe(data);
193         } else
194                 ret = really_probe(data);
195
196 done:
197         return ret;
198 }
199
200 static int __device_attach(struct device_driver * drv, void * data)
201 {
202         struct device * dev = data;
203         return driver_probe_device(drv, dev);
204 }
205
206 /**
207  *      device_attach - try to attach device to a driver.
208  *      @dev:   device.
209  *
210  *      Walk the list of drivers that the bus has and call
211  *      driver_probe_device() for each pair. If a compatible
212  *      pair is found, break out and return.
213  *
214  *      Returns 1 if the device was bound to a driver;
215  *      0 if no matching device was found; error code otherwise.
216  *
217  *      When called for a USB interface, @dev->parent->sem must be held.
218  */
219 int device_attach(struct device * dev)
220 {
221         int ret = 0;
222
223         down(&dev->sem);
224         if (dev->driver) {
225                 ret = device_bind_driver(dev);
226                 if (ret == 0)
227                         ret = 1;
228         } else
229                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
230         up(&dev->sem);
231         return ret;
232 }
233
234 static int __driver_attach(struct device * dev, void * data)
235 {
236         struct device_driver * drv = data;
237
238         /*
239          * Lock device and try to bind to it. We drop the error
240          * here and always return 0, because we need to keep trying
241          * to bind to devices and some drivers will return an error
242          * simply if it didn't support the device.
243          *
244          * driver_probe_device() will spit a warning if there
245          * is an error.
246          */
247
248         if (dev->parent)        /* Needed for USB */
249                 down(&dev->parent->sem);
250         down(&dev->sem);
251         if (!dev->driver)
252                 driver_probe_device(drv, dev);
253         up(&dev->sem);
254         if (dev->parent)
255                 up(&dev->parent->sem);
256
257         return 0;
258 }
259
260 /**
261  *      driver_attach - try to bind driver to devices.
262  *      @drv:   driver.
263  *
264  *      Walk the list of devices that the bus has on it and try to
265  *      match the driver with each one.  If driver_probe_device()
266  *      returns 0 and the @dev->driver is set, we've found a
267  *      compatible pair.
268  */
269 int driver_attach(struct device_driver * drv)
270 {
271         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
272 }
273
274 /**
275  *      device_release_driver - manually detach device from driver.
276  *      @dev:   device.
277  *
278  *      Manually detach device from driver.
279  *
280  *      __device_release_driver() must be called with @dev->sem held.
281  *      When called for a USB interface, @dev->parent->sem must be held
282  *      as well.
283  */
284
285 static void __device_release_driver(struct device * dev)
286 {
287         struct device_driver * drv;
288
289         drv = dev->driver;
290         if (drv) {
291                 get_driver(drv);
292                 sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
293                 sysfs_remove_link(&dev->kobj, "driver");
294                 klist_remove(&dev->knode_driver);
295
296                 if (dev->bus)
297                         blocking_notifier_call_chain(&dev->bus->bus_notifier,
298                                                      BUS_NOTIFY_UNBIND_DRIVER,
299                                                      dev);
300
301                 if (dev->bus && dev->bus->remove)
302                         dev->bus->remove(dev);
303                 else if (drv->remove)
304                         drv->remove(dev);
305                 dev->driver = NULL;
306                 put_driver(drv);
307         }
308 }
309
310 void device_release_driver(struct device * dev)
311 {
312         /*
313          * If anyone calls device_release_driver() recursively from
314          * within their ->remove callback for the same device, they
315          * will deadlock right here.
316          */
317         down(&dev->sem);
318         __device_release_driver(dev);
319         up(&dev->sem);
320 }
321
322
323 /**
324  * driver_detach - detach driver from all devices it controls.
325  * @drv: driver.
326  */
327 void driver_detach(struct device_driver * drv)
328 {
329         struct device * dev;
330
331         for (;;) {
332                 spin_lock(&drv->klist_devices.k_lock);
333                 if (list_empty(&drv->klist_devices.k_list)) {
334                         spin_unlock(&drv->klist_devices.k_lock);
335                         break;
336                 }
337                 dev = list_entry(drv->klist_devices.k_list.prev,
338                                 struct device, knode_driver.n_node);
339                 get_device(dev);
340                 spin_unlock(&drv->klist_devices.k_lock);
341
342                 if (dev->parent)        /* Needed for USB */
343                         down(&dev->parent->sem);
344                 down(&dev->sem);
345                 if (dev->driver == drv)
346                         __device_release_driver(dev);
347                 up(&dev->sem);
348                 if (dev->parent)
349                         up(&dev->parent->sem);
350                 put_device(dev);
351         }
352 }
353
354 #ifdef CONFIG_PCI_MULTITHREAD_PROBE
355 static int __init wait_for_probes(void)
356 {
357         DEFINE_WAIT(wait);
358
359         printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__,
360                         atomic_read(&probe_count));
361         if (!atomic_read(&probe_count))
362                 return 0;
363         while (atomic_read(&probe_count)) {
364                 prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE);
365                 if (atomic_read(&probe_count))
366                         schedule();
367         }
368         finish_wait(&probe_waitqueue, &wait);
369         return 0;
370 }
371
372 core_initcall_sync(wait_for_probes);
373 postcore_initcall_sync(wait_for_probes);
374 arch_initcall_sync(wait_for_probes);
375 subsys_initcall_sync(wait_for_probes);
376 fs_initcall_sync(wait_for_probes);
377 device_initcall_sync(wait_for_probes);
378 late_initcall_sync(wait_for_probes);
379 #endif
380
381 EXPORT_SYMBOL_GPL(device_bind_driver);
382 EXPORT_SYMBOL_GPL(device_release_driver);
383 EXPORT_SYMBOL_GPL(device_attach);
384 EXPORT_SYMBOL_GPL(driver_attach);
385