Driver core: fix "driver" symlink timing
[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         driver_bound(dev);
90         return driver_sysfs_add(dev);
91 }
92
93 struct stupid_thread_structure {
94         struct device_driver *drv;
95         struct device *dev;
96 };
97
98 static atomic_t probe_count = ATOMIC_INIT(0);
99 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
100
101 static int really_probe(void *void_data)
102 {
103         struct stupid_thread_structure *data = void_data;
104         struct device_driver *drv = data->drv;
105         struct device *dev = data->dev;
106         int ret = 0;
107
108         atomic_inc(&probe_count);
109         pr_debug("%s: Probing driver %s with device %s\n",
110                  drv->bus->name, drv->name, dev->bus_id);
111
112         dev->driver = drv;
113         if (driver_sysfs_add(dev)) {
114                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
115                         __FUNCTION__, dev->bus_id);
116                 goto probe_failed;
117         }
118
119         if (dev->bus->probe) {
120                 ret = dev->bus->probe(dev);
121                 if (ret)
122                         goto probe_failed;
123         } else if (drv->probe) {
124                 ret = drv->probe(dev);
125                 if (ret)
126                         goto probe_failed;
127         }
128
129         driver_bound(dev);
130         ret = 1;
131         pr_debug("%s: Bound Device %s to Driver %s\n",
132                  drv->bus->name, dev->bus_id, drv->name);
133         goto done;
134
135 probe_failed:
136         driver_sysfs_remove(dev);
137         dev->driver = NULL;
138
139         if (ret == -ENODEV || ret == -ENXIO) {
140                 /* Driver matched, but didn't support device
141                  * or device not found.
142                  * Not an error; keep going.
143                  */
144                 ret = 0;
145         } else {
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 done:
152         kfree(data);
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", __FUNCTION__,
167                  atomic_read(&probe_count));
168         if (atomic_read(&probe_count))
169                 return -EBUSY;
170         return 0;
171 }
172
173 /**
174  * driver_probe_device - attempt to bind device & driver together
175  * @drv: driver to bind a device to
176  * @dev: device to try to bind to the driver
177  *
178  * First, we call the bus's match function, if one present, which should
179  * compare the device IDs the driver supports with the device IDs of the
180  * device. Note we don't do this ourselves because we don't know the
181  * format of the ID structures, nor what is to be considered a match and
182  * what is not.
183  *
184  * This function returns 1 if a match is found, an error if one occurs
185  * (that is not -ENODEV or -ENXIO), and 0 otherwise.
186  *
187  * This function must be called with @dev->sem held.  When called for a
188  * USB interface, @dev->parent->sem must be held as well.
189  */
190 int driver_probe_device(struct device_driver * drv, struct device * dev)
191 {
192         struct stupid_thread_structure *data;
193         struct task_struct *probe_task;
194         int ret = 0;
195
196         if (!device_is_registered(dev))
197                 return -ENODEV;
198         if (drv->bus->match && !drv->bus->match(dev, drv))
199                 goto done;
200
201         pr_debug("%s: Matched Device %s with Driver %s\n",
202                  drv->bus->name, dev->bus_id, drv->name);
203
204         data = kmalloc(sizeof(*data), GFP_KERNEL);
205         if (!data)
206                 return -ENOMEM;
207         data->drv = drv;
208         data->dev = dev;
209
210         if (drv->multithread_probe) {
211                 probe_task = kthread_run(really_probe, data,
212                                          "probe-%s", dev->bus_id);
213                 if (IS_ERR(probe_task))
214                         ret = really_probe(data);
215         } else
216                 ret = really_probe(data);
217
218 done:
219         return ret;
220 }
221
222 static int __device_attach(struct device_driver * drv, void * data)
223 {
224         struct device * dev = data;
225         return driver_probe_device(drv, dev);
226 }
227
228 /**
229  *      device_attach - try to attach device to a driver.
230  *      @dev:   device.
231  *
232  *      Walk the list of drivers that the bus has and call
233  *      driver_probe_device() for each pair. If a compatible
234  *      pair is found, break out and return.
235  *
236  *      Returns 1 if the device was bound to a driver;
237  *      0 if no matching device was found; error code otherwise.
238  *
239  *      When called for a USB interface, @dev->parent->sem must be held.
240  */
241 int device_attach(struct device * dev)
242 {
243         int ret = 0;
244
245         down(&dev->sem);
246         if (dev->driver) {
247                 ret = device_bind_driver(dev);
248                 if (ret == 0)
249                         ret = 1;
250         } else
251                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
252         up(&dev->sem);
253         return ret;
254 }
255
256 static int __driver_attach(struct device * dev, void * data)
257 {
258         struct device_driver * drv = data;
259
260         /*
261          * Lock device and try to bind to it. We drop the error
262          * here and always return 0, because we need to keep trying
263          * to bind to devices and some drivers will return an error
264          * simply if it didn't support the device.
265          *
266          * driver_probe_device() will spit a warning if there
267          * is an error.
268          */
269
270         if (dev->parent)        /* Needed for USB */
271                 down(&dev->parent->sem);
272         down(&dev->sem);
273         if (!dev->driver)
274                 driver_probe_device(drv, dev);
275         up(&dev->sem);
276         if (dev->parent)
277                 up(&dev->parent->sem);
278
279         return 0;
280 }
281
282 /**
283  *      driver_attach - try to bind driver to devices.
284  *      @drv:   driver.
285  *
286  *      Walk the list of devices that the bus has on it and try to
287  *      match the driver with each one.  If driver_probe_device()
288  *      returns 0 and the @dev->driver is set, we've found a
289  *      compatible pair.
290  */
291 int driver_attach(struct device_driver * drv)
292 {
293         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
294 }
295
296 /**
297  *      device_release_driver - manually detach device from driver.
298  *      @dev:   device.
299  *
300  *      Manually detach device from driver.
301  *
302  *      __device_release_driver() must be called with @dev->sem held.
303  *      When called for a USB interface, @dev->parent->sem must be held
304  *      as well.
305  */
306
307 static void __device_release_driver(struct device * dev)
308 {
309         struct device_driver * drv;
310
311         drv = dev->driver;
312         if (drv) {
313                 get_driver(drv);
314                 driver_sysfs_remove(dev);
315                 sysfs_remove_link(&dev->kobj, "driver");
316                 klist_remove(&dev->knode_driver);
317
318                 if (dev->bus)
319                         blocking_notifier_call_chain(&dev->bus->bus_notifier,
320                                                      BUS_NOTIFY_UNBIND_DRIVER,
321                                                      dev);
322
323                 if (dev->bus && dev->bus->remove)
324                         dev->bus->remove(dev);
325                 else if (drv->remove)
326                         drv->remove(dev);
327                 dev->driver = NULL;
328                 put_driver(drv);
329         }
330 }
331
332 void device_release_driver(struct device * dev)
333 {
334         /*
335          * If anyone calls device_release_driver() recursively from
336          * within their ->remove callback for the same device, they
337          * will deadlock right here.
338          */
339         down(&dev->sem);
340         __device_release_driver(dev);
341         up(&dev->sem);
342 }
343
344
345 /**
346  * driver_detach - detach driver from all devices it controls.
347  * @drv: driver.
348  */
349 void driver_detach(struct device_driver * drv)
350 {
351         struct device * dev;
352
353         for (;;) {
354                 spin_lock(&drv->klist_devices.k_lock);
355                 if (list_empty(&drv->klist_devices.k_list)) {
356                         spin_unlock(&drv->klist_devices.k_lock);
357                         break;
358                 }
359                 dev = list_entry(drv->klist_devices.k_list.prev,
360                                 struct device, knode_driver.n_node);
361                 get_device(dev);
362                 spin_unlock(&drv->klist_devices.k_lock);
363
364                 if (dev->parent)        /* Needed for USB */
365                         down(&dev->parent->sem);
366                 down(&dev->sem);
367                 if (dev->driver == drv)
368                         __device_release_driver(dev);
369                 up(&dev->sem);
370                 if (dev->parent)
371                         up(&dev->parent->sem);
372                 put_device(dev);
373         }
374 }
375
376 #ifdef CONFIG_PCI_MULTITHREAD_PROBE
377 static int __init wait_for_probes(void)
378 {
379         DEFINE_WAIT(wait);
380
381         printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__,
382                         atomic_read(&probe_count));
383         if (!atomic_read(&probe_count))
384                 return 0;
385         while (atomic_read(&probe_count)) {
386                 prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE);
387                 if (atomic_read(&probe_count))
388                         schedule();
389         }
390         finish_wait(&probe_waitqueue, &wait);
391         return 0;
392 }
393
394 core_initcall_sync(wait_for_probes);
395 postcore_initcall_sync(wait_for_probes);
396 arch_initcall_sync(wait_for_probes);
397 subsys_initcall_sync(wait_for_probes);
398 fs_initcall_sync(wait_for_probes);
399 device_initcall_sync(wait_for_probes);
400 late_initcall_sync(wait_for_probes);
401 #endif
402
403 EXPORT_SYMBOL_GPL(device_bind_driver);
404 EXPORT_SYMBOL_GPL(device_release_driver);
405 EXPORT_SYMBOL_GPL(device_attach);
406 EXPORT_SYMBOL_GPL(driver_attach);
407