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