6a48824e43ff6559ff386d4eb23c301e5293d753
[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         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                         __FUNCTION__, dev->bus_id);
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("%s: Bound Device %s to Driver %s\n",
137                  drv->bus->name, dev->bus_id, 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->bus_id, ret);
150         }
151         /*
152          * Ignore errors returned by ->probe so that the next driver can try
153          * its luck.
154          */
155         ret = 0;
156 done:
157         kfree(data);
158         atomic_dec(&probe_count);
159         wake_up(&probe_waitqueue);
160         return ret;
161 }
162
163 /**
164  * driver_probe_done
165  * Determine if the probe sequence is finished or not.
166  *
167  * Should somehow figure out how to use a semaphore, not an atomic variable...
168  */
169 int driver_probe_done(void)
170 {
171         pr_debug("%s: probe_count = %d\n", __FUNCTION__,
172                  atomic_read(&probe_count));
173         if (atomic_read(&probe_count))
174                 return -EBUSY;
175         return 0;
176 }
177
178 /**
179  * driver_probe_device - attempt to bind device & driver together
180  * @drv: driver to bind a device to
181  * @dev: device to try to bind to the driver
182  *
183  * First, we call the bus's match function, if one present, which should
184  * compare the device IDs the driver supports with the device IDs of the
185  * device. Note we don't do this ourselves because we don't know the
186  * format of the ID structures, nor what is to be considered a match and
187  * what is not.
188  *
189  * This function returns 1 if a match is found, an error if one occurs
190  * (that is not -ENODEV or -ENXIO), and 0 otherwise.
191  *
192  * This function must be called with @dev->sem held.  When called for a
193  * USB interface, @dev->parent->sem must be held as well.
194  */
195 int driver_probe_device(struct device_driver * drv, struct device * dev)
196 {
197         struct stupid_thread_structure *data;
198         struct task_struct *probe_task;
199         int ret = 0;
200
201         if (!device_is_registered(dev))
202                 return -ENODEV;
203         if (drv->bus->match && !drv->bus->match(dev, drv))
204                 goto done;
205
206         pr_debug("%s: Matched Device %s with Driver %s\n",
207                  drv->bus->name, dev->bus_id, drv->name);
208
209         data = kmalloc(sizeof(*data), GFP_KERNEL);
210         if (!data)
211                 return -ENOMEM;
212         data->drv = drv;
213         data->dev = dev;
214
215         if (drv->multithread_probe) {
216                 probe_task = kthread_run(really_probe, data,
217                                          "probe-%s", dev->bus_id);
218                 if (IS_ERR(probe_task))
219                         ret = really_probe(data);
220         } else
221                 ret = really_probe(data);
222
223 done:
224         return ret;
225 }
226
227 static int __device_attach(struct device_driver * drv, void * data)
228 {
229         struct device * dev = data;
230         return driver_probe_device(drv, dev);
231 }
232
233 /**
234  *      device_attach - try to attach device to a driver.
235  *      @dev:   device.
236  *
237  *      Walk the list of drivers that the bus has and call
238  *      driver_probe_device() for each pair. If a compatible
239  *      pair is found, break out and return.
240  *
241  *      Returns 1 if the device was bound to a driver;
242  *      0 if no matching device was found; error code otherwise.
243  *
244  *      When called for a USB interface, @dev->parent->sem must be held.
245  */
246 int device_attach(struct device * dev)
247 {
248         int ret = 0;
249
250         down(&dev->sem);
251         if (dev->driver) {
252                 ret = device_bind_driver(dev);
253                 if (ret == 0)
254                         ret = 1;
255         } else
256                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
257         up(&dev->sem);
258         return ret;
259 }
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 (dev->parent)        /* Needed for USB */
276                 down(&dev->parent->sem);
277         down(&dev->sem);
278         if (!dev->driver)
279                 driver_probe_device(drv, dev);
280         up(&dev->sem);
281         if (dev->parent)
282                 up(&dev->parent->sem);
283
284         return 0;
285 }
286
287 /**
288  *      driver_attach - try to bind driver to devices.
289  *      @drv:   driver.
290  *
291  *      Walk the list of devices that the bus has on it and try to
292  *      match the driver with each one.  If driver_probe_device()
293  *      returns 0 and the @dev->driver is set, we've found a
294  *      compatible pair.
295  */
296 int driver_attach(struct device_driver * drv)
297 {
298         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
299 }
300
301 /**
302  *      device_release_driver - manually detach device from driver.
303  *      @dev:   device.
304  *
305  *      Manually detach device from driver.
306  *
307  *      __device_release_driver() must be called with @dev->sem held.
308  *      When called for a USB interface, @dev->parent->sem must be held
309  *      as well.
310  */
311
312 static void __device_release_driver(struct device * dev)
313 {
314         struct device_driver * drv;
315
316         drv = dev->driver;
317         if (drv) {
318                 get_driver(drv);
319                 driver_sysfs_remove(dev);
320                 sysfs_remove_link(&dev->kobj, "driver");
321                 klist_remove(&dev->knode_driver);
322
323                 if (dev->bus)
324                         blocking_notifier_call_chain(&dev->bus->bus_notifier,
325                                                      BUS_NOTIFY_UNBIND_DRIVER,
326                                                      dev);
327
328                 if (dev->bus && dev->bus->remove)
329                         dev->bus->remove(dev);
330                 else if (drv->remove)
331                         drv->remove(dev);
332                 devres_release_all(dev);
333                 dev->driver = NULL;
334                 put_driver(drv);
335         }
336 }
337
338 void device_release_driver(struct device * dev)
339 {
340         /*
341          * If anyone calls device_release_driver() recursively from
342          * within their ->remove callback for the same device, they
343          * will deadlock right here.
344          */
345         down(&dev->sem);
346         __device_release_driver(dev);
347         up(&dev->sem);
348 }
349
350
351 /**
352  * driver_detach - detach driver from all devices it controls.
353  * @drv: driver.
354  */
355 void driver_detach(struct device_driver * drv)
356 {
357         struct device * dev;
358
359         for (;;) {
360                 spin_lock(&drv->klist_devices.k_lock);
361                 if (list_empty(&drv->klist_devices.k_list)) {
362                         spin_unlock(&drv->klist_devices.k_lock);
363                         break;
364                 }
365                 dev = list_entry(drv->klist_devices.k_list.prev,
366                                 struct device, knode_driver.n_node);
367                 get_device(dev);
368                 spin_unlock(&drv->klist_devices.k_lock);
369
370                 if (dev->parent)        /* Needed for USB */
371                         down(&dev->parent->sem);
372                 down(&dev->sem);
373                 if (dev->driver == drv)
374                         __device_release_driver(dev);
375                 up(&dev->sem);
376                 if (dev->parent)
377                         up(&dev->parent->sem);
378                 put_device(dev);
379         }
380 }
381
382 #ifdef CONFIG_PCI_MULTITHREAD_PROBE
383 static int __init wait_for_probes(void)
384 {
385         DEFINE_WAIT(wait);
386
387         printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__,
388                         atomic_read(&probe_count));
389         if (!atomic_read(&probe_count))
390                 return 0;
391         while (atomic_read(&probe_count)) {
392                 prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE);
393                 if (atomic_read(&probe_count))
394                         schedule();
395         }
396         finish_wait(&probe_waitqueue, &wait);
397         return 0;
398 }
399
400 core_initcall_sync(wait_for_probes);
401 postcore_initcall_sync(wait_for_probes);
402 arch_initcall_sync(wait_for_probes);
403 subsys_initcall_sync(wait_for_probes);
404 fs_initcall_sync(wait_for_probes);
405 device_initcall_sync(wait_for_probes);
406 late_initcall_sync(wait_for_probes);
407 #endif
408
409 EXPORT_SYMBOL_GPL(device_bind_driver);
410 EXPORT_SYMBOL_GPL(device_release_driver);
411 EXPORT_SYMBOL_GPL(device_attach);
412 EXPORT_SYMBOL_GPL(driver_attach);
413