driver core: Don't stop probing on ->probe errors.
[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 the probe failed */
141                 printk(KERN_WARNING
142                        "%s: probe of %s failed with error %d\n",
143                        drv->name, dev->bus_id, ret);
144         }
145         /*
146          * Ignore errors returned by ->probe so that the next driver can try
147          * its luck.
148          */
149         ret = 0;
150 done:
151         kfree(data);
152         atomic_dec(&probe_count);
153         wake_up(&probe_waitqueue);
154         return ret;
155 }
156
157 /**
158  * driver_probe_done
159  * Determine if the probe sequence is finished or not.
160  *
161  * Should somehow figure out how to use a semaphore, not an atomic variable...
162  */
163 int driver_probe_done(void)
164 {
165         pr_debug("%s: probe_count = %d\n", __FUNCTION__,
166                  atomic_read(&probe_count));
167         if (atomic_read(&probe_count))
168                 return -EBUSY;
169         return 0;
170 }
171
172 /**
173  * driver_probe_device - attempt to bind device & driver together
174  * @drv: driver to bind a device to
175  * @dev: device to try to bind to the driver
176  *
177  * First, we call the bus's match function, if one present, which should
178  * compare the device IDs the driver supports with the device IDs of the
179  * device. Note we don't do this ourselves because we don't know the
180  * format of the ID structures, nor what is to be considered a match and
181  * what is not.
182  *
183  * This function returns 1 if a match is found, an error if one occurs
184  * (that is not -ENODEV or -ENXIO), and 0 otherwise.
185  *
186  * This function must be called with @dev->sem held.  When called for a
187  * USB interface, @dev->parent->sem must be held as well.
188  */
189 int driver_probe_device(struct device_driver * drv, struct device * dev)
190 {
191         struct stupid_thread_structure *data;
192         struct task_struct *probe_task;
193         int ret = 0;
194
195         if (!device_is_registered(dev))
196                 return -ENODEV;
197         if (drv->bus->match && !drv->bus->match(dev, drv))
198                 goto done;
199
200         pr_debug("%s: Matched Device %s with Driver %s\n",
201                  drv->bus->name, dev->bus_id, drv->name);
202
203         data = kmalloc(sizeof(*data), GFP_KERNEL);
204         if (!data)
205                 return -ENOMEM;
206         data->drv = drv;
207         data->dev = dev;
208
209         if (drv->multithread_probe) {
210                 probe_task = kthread_run(really_probe, data,
211                                          "probe-%s", dev->bus_id);
212                 if (IS_ERR(probe_task))
213                         ret = really_probe(data);
214         } else
215                 ret = really_probe(data);
216
217 done:
218         return ret;
219 }
220
221 static int __device_attach(struct device_driver * drv, void * data)
222 {
223         struct device * dev = data;
224         return driver_probe_device(drv, dev);
225 }
226
227 /**
228  *      device_attach - try to attach device to a driver.
229  *      @dev:   device.
230  *
231  *      Walk the list of drivers that the bus has and call
232  *      driver_probe_device() for each pair. If a compatible
233  *      pair is found, break out and return.
234  *
235  *      Returns 1 if the device was bound to a driver;
236  *      0 if no matching device was found; error code otherwise.
237  *
238  *      When called for a USB interface, @dev->parent->sem must be held.
239  */
240 int device_attach(struct device * dev)
241 {
242         int ret = 0;
243
244         down(&dev->sem);
245         if (dev->driver) {
246                 ret = device_bind_driver(dev);
247                 if (ret == 0)
248                         ret = 1;
249         } else
250                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
251         up(&dev->sem);
252         return ret;
253 }
254
255 static int __driver_attach(struct device * dev, void * data)
256 {
257         struct device_driver * drv = data;
258
259         /*
260          * Lock device and try to bind to it. We drop the error
261          * here and always return 0, because we need to keep trying
262          * to bind to devices and some drivers will return an error
263          * simply if it didn't support the device.
264          *
265          * driver_probe_device() will spit a warning if there
266          * is an error.
267          */
268
269         if (dev->parent)        /* Needed for USB */
270                 down(&dev->parent->sem);
271         down(&dev->sem);
272         if (!dev->driver)
273                 driver_probe_device(drv, dev);
274         up(&dev->sem);
275         if (dev->parent)
276                 up(&dev->parent->sem);
277
278         return 0;
279 }
280
281 /**
282  *      driver_attach - try to bind driver to devices.
283  *      @drv:   driver.
284  *
285  *      Walk the list of devices that the bus has on it and try to
286  *      match the driver with each one.  If driver_probe_device()
287  *      returns 0 and the @dev->driver is set, we've found a
288  *      compatible pair.
289  */
290 int driver_attach(struct device_driver * drv)
291 {
292         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
293 }
294
295 /**
296  *      device_release_driver - manually detach device from driver.
297  *      @dev:   device.
298  *
299  *      Manually detach device from driver.
300  *
301  *      __device_release_driver() must be called with @dev->sem held.
302  *      When called for a USB interface, @dev->parent->sem must be held
303  *      as well.
304  */
305
306 static void __device_release_driver(struct device * dev)
307 {
308         struct device_driver * drv;
309
310         drv = dev->driver;
311         if (drv) {
312                 get_driver(drv);
313                 driver_sysfs_remove(dev);
314                 sysfs_remove_link(&dev->kobj, "driver");
315                 klist_remove(&dev->knode_driver);
316
317                 if (dev->bus)
318                         blocking_notifier_call_chain(&dev->bus->bus_notifier,
319                                                      BUS_NOTIFY_UNBIND_DRIVER,
320                                                      dev);
321
322                 if (dev->bus && dev->bus->remove)
323                         dev->bus->remove(dev);
324                 else if (drv->remove)
325                         drv->remove(dev);
326                 dev->driver = NULL;
327                 put_driver(drv);
328         }
329 }
330
331 void device_release_driver(struct device * dev)
332 {
333         /*
334          * If anyone calls device_release_driver() recursively from
335          * within their ->remove callback for the same device, they
336          * will deadlock right here.
337          */
338         down(&dev->sem);
339         __device_release_driver(dev);
340         up(&dev->sem);
341 }
342
343
344 /**
345  * driver_detach - detach driver from all devices it controls.
346  * @drv: driver.
347  */
348 void driver_detach(struct device_driver * drv)
349 {
350         struct device * dev;
351
352         for (;;) {
353                 spin_lock(&drv->klist_devices.k_lock);
354                 if (list_empty(&drv->klist_devices.k_list)) {
355                         spin_unlock(&drv->klist_devices.k_lock);
356                         break;
357                 }
358                 dev = list_entry(drv->klist_devices.k_list.prev,
359                                 struct device, knode_driver.n_node);
360                 get_device(dev);
361                 spin_unlock(&drv->klist_devices.k_lock);
362
363                 if (dev->parent)        /* Needed for USB */
364                         down(&dev->parent->sem);
365                 down(&dev->sem);
366                 if (dev->driver == drv)
367                         __device_release_driver(dev);
368                 up(&dev->sem);
369                 if (dev->parent)
370                         up(&dev->parent->sem);
371                 put_device(dev);
372         }
373 }
374
375 #ifdef CONFIG_PCI_MULTITHREAD_PROBE
376 static int __init wait_for_probes(void)
377 {
378         DEFINE_WAIT(wait);
379
380         printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__,
381                         atomic_read(&probe_count));
382         if (!atomic_read(&probe_count))
383                 return 0;
384         while (atomic_read(&probe_count)) {
385                 prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE);
386                 if (atomic_read(&probe_count))
387                         schedule();
388         }
389         finish_wait(&probe_waitqueue, &wait);
390         return 0;
391 }
392
393 core_initcall_sync(wait_for_probes);
394 postcore_initcall_sync(wait_for_probes);
395 arch_initcall_sync(wait_for_probes);
396 subsys_initcall_sync(wait_for_probes);
397 fs_initcall_sync(wait_for_probes);
398 device_initcall_sync(wait_for_probes);
399 late_initcall_sync(wait_for_probes);
400 #endif
401
402 EXPORT_SYMBOL_GPL(device_bind_driver);
403 EXPORT_SYMBOL_GPL(device_release_driver);
404 EXPORT_SYMBOL_GPL(device_attach);
405 EXPORT_SYMBOL_GPL(driver_attach);
406