summaryrefslogtreecommitdiffstats
path: root/drivers/base/dd.c
blob: 3565e9795301d6d90a72ce2e433313a635df5c1c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
/*
 *	drivers/base/dd.c - The core device/driver interactions.
 *
 * 	This file contains the (sometimes tricky) code that controls the
 *	interactions between devices and drivers, which primarily includes
 *	driver binding and unbinding.
 *
 *	All of this code used to exist in drivers/base/bus.c, but was
 *	relocated to here in the name of compartmentalization (since it wasn't
 *	strictly code just for the 'struct bus_type'.
 *
 *	Copyright (c) 2002-5 Patrick Mochel
 *	Copyright (c) 2002-3 Open Source Development Labs
 *
 *	This file is released under the GPLv2
 */

#include <linux/device.h>
#include <linux/module.h>

#include "base.h"
#include "power/power.h"

#define to_drv(node) container_of(node, struct device_driver, kobj.entry)


/**
 *	device_bind_driver - bind a driver to one device.
 *	@dev:	device.
 *
 *	Allow manual attachment of a driver to a device.
 *	Caller must have already set @dev->driver.
 *
 *	Note that this does not modify the bus reference count
 *	nor take the bus's rwsem. Please verify those are accounted
 *	for before calling this. (It is ok to call with no other effort
 *	from a driver's probe() method.)
 *
 *	This function must be called with @dev->sem held.
 */
void device_bind_driver(struct device * dev)
{
	if (klist_node_attached(&dev->knode_driver))
		return;

	pr_debug("bound device '%s' to driver '%s'\n",
		 dev->bus_id, dev->driver->name);
	klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices);
	sysfs_create_link(&dev->driver->kobj, &dev->kobj,
			  kobject_name(&dev->kobj));
	sysfs_create_link(&dev->kobj, &dev->driver->kobj, "driver");
}

/**
 *	driver_probe_device - attempt to bind device & driver.
 *	@drv:	driver.
 *	@dev:	device.
 *
 *	First, we call the bus's match function, if one present, which
 *	should compare the device IDs the driver supports with the
 *	device IDs of the device. Note we don't do this ourselves
 *	because we don't know the format of the ID structures, nor what
 *	is to be considered a match and what is not.
 *
 *
 *	This function returns 1 if a match is found, an error if one
 *	occurs (that is not -ENODEV or -ENXIO), and 0 otherwise.
 *
 *	This function must be called with @dev->sem held.
 */
int driver_probe_device(struct device_driver * drv, struct device * dev)
{
	int ret = 0;

	if (drv->bus->match && !drv->bus->match(dev, drv))
		goto Done;

	pr_debug("%s: Matched Device %s with Driver %s\n",
		 drv->bus->name, dev->bus_id, drv->name);
	dev->driver = drv;
	if (drv->probe) {
		ret = drv->probe(dev);
		if (ret) {
			dev->driver = NULL;
			goto ProbeFailed;
		}
	}
	device_bind_driver(dev);
	ret = 1;
	pr_debug("%s: Bound Device %s to Driver %s\n",
		 drv->bus->name, dev->bus_id, drv->name);
	goto Done;

 ProbeFailed:
	if (ret == -ENODEV || ret == -ENXIO) {
		/* Driver matched, but didn't support device
		 * or device not found.
		 * Not an error; keep going.
		 */
		ret = 0;
	} else {
		/* driver matched but the probe failed */
		printk(KERN_WARNING
		       "%s: probe of %s failed with error %d\n",
		       drv->name, dev->bus_id, ret);
	}
 Done:
	return ret;
}

static int __device_attach(struct device_driver * drv, void * data)
{
	struct device * dev = data;
	return driver_probe_device(drv, dev);
}

/**
 *	device_attach - try to attach device to a driver.
 *	@dev:	device.
 *
 *	Walk the list of drivers that the bus has and call
 *	driver_probe_device() for each pair. If a compatible
 *	pair is found, break out and return.
 *
 *	Returns 1 if the device was bound to a driver;
 *	0 if no matching device was found; error code otherwise.
 */
int device_attach(struct device * dev)
{
	int ret = 0;

	down(&dev->sem);
	if (dev->driver) {
		device_bind_driver(dev);
		ret = 1;
	} else
		ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
	up(&dev->sem);
	return ret;
}

static int __driver_attach(struct device * dev, void * data)
{
	struct device_driver * drv = data;

	/*
	 * Lock device and try to bind to it. We drop the error
	 * here and always return 0, because we need to keep trying
	 * to bind to devices and some drivers will return an error
	 * simply if it didn't support the device.
	 *
	 * driver_probe_device() will spit a warning if there
	 * is an error.
	 */

	down(&dev->sem);
	if (!dev->driver)
		driver_probe_device(drv, dev);
	up(&dev->sem);


	return 0;
}

/**
 *	driver_attach - try to bind driver to devices.
 *	@drv:	driver.
 *
 *	Walk the list of devices that the bus has on it and try to
 *	match the driver with each one.  If driver_probe_device()
 *	returns 0 and the @dev->driver is set, we've found a
 *	compatible pair.
 */
void driver_attach(struct device_driver * drv)
{
	bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
}

/**
 *	device_release_driver - manually detach device from driver.
 *	@dev:	device.
 *
 *	Manually detach device from driver.
 *
 *	__device_release_driver() must be called with @dev->sem held.
 */

static void __device_release_driver(struct device * dev)
{
	struct device_driver * drv;

	drv = dev->driver;
	if (drv) {
		get_driver(drv);
		sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
		sysfs_remove_link(&dev->kobj, "driver");
		klist_remove(&dev->knode_driver);

		if (drv->remove)
			drv->remove(dev);
		dev->driver = NULL;
		put_driver(drv);
	}
}

void device_release_driver(struct device * dev)
{
	/*
	 * If anyone calls device_release_driver() recursively from
	 * within their ->remove callback for the same device, they
	 * will deadlock right here.
	 */
	down(&dev->sem);
	__device_release_driver(dev);
	up(&dev->sem);
}


/**
 * driver_detach - detach driver from all devices it controls.
 * @drv: driver.
 */
void driver_detach(struct device_driver * drv)
{
	struct device * dev;

	for (;;) {
		spin_lock_irq(&drv->klist_devices.k_lock);
		if (list_empty(&drv->klist_devices.k_list)) {
			spin_unlock_irq(&drv->klist_devices.k_lock);
			break;
		}
		dev = list_entry(drv->klist_devices.k_list.prev,
				struct device, knode_driver.n_node);
		get_device(dev);
		spin_unlock_irq(&drv->klist_devices.k_lock);

		down(&dev->sem);
		if (dev->driver == drv)
			__device_release_driver(dev);
		up(&dev->sem);
		put_device(dev);
	}
}


EXPORT_SYMBOL_GPL(device_bind_driver);
EXPORT_SYMBOL_GPL(device_release_driver);
EXPORT_SYMBOL_GPL(device_attach);
EXPORT_SYMBOL_GPL(driver_attach);