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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 | |
21 | #include "base.h" |
22 | #include "power/power.h" |
23 | |
24 | #define to_drv(node) container_of(node, struct device_driver, kobj.entry) |
25 | |
26 | |
27 | /** |
28 | * device_bind_driver - bind a driver to one device. |
29 | * @dev: device. |
30 | * |
31 | * Allow manual attachment of a driver to a device. |
32 | * Caller must have already set @dev->driver. |
33 | * |
34 | * Note that this does not modify the bus reference count |
35 | * nor take the bus's rwsem. Please verify those are accounted |
36 | * for before calling this. (It is ok to call with no other effort |
37 | * from a driver's probe() method.) |
38 | */ |
39 | void device_bind_driver(struct device * dev) |
40 | { |
41 | pr_debug("bound device '%s' to driver '%s'\n", |
42 | dev->bus_id, dev->driver->name); |
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43 | klist_add_tail(&dev->driver->klist_devices, &dev->knode_driver); |
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44 | sysfs_create_link(&dev->driver->kobj, &dev->kobj, |
45 | kobject_name(&dev->kobj)); |
46 | sysfs_create_link(&dev->kobj, &dev->driver->kobj, "driver"); |
47 | } |
48 | |
49 | /** |
50 | * driver_probe_device - attempt to bind device & driver. |
51 | * @drv: driver. |
52 | * @dev: device. |
53 | * |
54 | * First, we call the bus's match function, if one present, which |
55 | * should compare the device IDs the driver supports with the |
56 | * device IDs of the device. Note we don't do this ourselves |
57 | * because we don't know the format of the ID structures, nor what |
58 | * is to be considered a match and what is not. |
59 | * |
60 | * If we find a match, we call @drv->probe(@dev) if it exists, and |
61 | * call device_bind_driver() above. |
62 | */ |
63 | int driver_probe_device(struct device_driver * drv, struct device * dev) |
64 | { |
65 | int error = 0; |
66 | |
67 | if (drv->bus->match && !drv->bus->match(dev, drv)) |
68 | return -ENODEV; |
69 | |
70 | down(&dev->sem); |
71 | dev->driver = drv; |
72 | if (drv->probe) { |
73 | error = drv->probe(dev); |
74 | if (error) { |
75 | dev->driver = NULL; |
76 | up(&dev->sem); |
77 | return error; |
78 | } |
79 | } |
80 | up(&dev->sem); |
81 | device_bind_driver(dev); |
82 | return 0; |
83 | } |
84 | |
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85 | static int __device_attach(struct device_driver * drv, void * data) |
86 | { |
87 | struct device * dev = data; |
88 | int error; |
89 | |
90 | error = driver_probe_device(drv, dev); |
91 | |
92 | if (error == -ENODEV && error == -ENXIO) { |
93 | /* Driver matched, but didn't support device |
94 | * or device not found. |
95 | * Not an error; keep going. |
96 | */ |
97 | error = 0; |
98 | } else { |
99 | /* driver matched but the probe failed */ |
100 | printk(KERN_WARNING |
101 | "%s: probe of %s failed with error %d\n", |
102 | drv->name, dev->bus_id, error); |
103 | } |
104 | return 0; |
105 | } |
106 | |
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107 | /** |
108 | * device_attach - try to attach device to a driver. |
109 | * @dev: device. |
110 | * |
111 | * Walk the list of drivers that the bus has and call |
112 | * driver_probe_device() for each pair. If a compatible |
113 | * pair is found, break out and return. |
114 | */ |
115 | int device_attach(struct device * dev) |
116 | { |
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117 | if (dev->driver) { |
118 | device_bind_driver(dev); |
119 | return 1; |
120 | } |
121 | |
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122 | return bus_for_each_drv(dev->bus, NULL, dev, __device_attach); |
123 | } |
124 | |
125 | static int __driver_attach(struct device * dev, void * data) |
126 | { |
127 | struct device_driver * drv = data; |
128 | int error = 0; |
129 | |
130 | if (!dev->driver) { |
131 | error = driver_probe_device(drv, dev); |
132 | if (error) { |
133 | if (error != -ENODEV) { |
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134 | /* driver matched but the probe failed */ |
135 | printk(KERN_WARNING |
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136 | "%s: probe of %s failed with error %d\n", |
137 | drv->name, dev->bus_id, error); |
138 | } else |
139 | error = 0; |
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140 | } |
141 | } |
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142 | return 0; |
143 | } |
144 | |
145 | /** |
146 | * driver_attach - try to bind driver to devices. |
147 | * @drv: driver. |
148 | * |
149 | * Walk the list of devices that the bus has on it and try to |
150 | * match the driver with each one. If driver_probe_device() |
151 | * returns 0 and the @dev->driver is set, we've found a |
152 | * compatible pair. |
153 | * |
154 | * Note that we ignore the -ENODEV error from driver_probe_device(), |
155 | * since it's perfectly valid for a driver not to bind to any devices. |
156 | */ |
157 | void driver_attach(struct device_driver * drv) |
158 | { |
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159 | bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); |
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160 | } |
161 | |
162 | /** |
163 | * device_release_driver - manually detach device from driver. |
164 | * @dev: device. |
165 | * |
166 | * Manually detach device from driver. |
167 | * Note that this is called without incrementing the bus |
168 | * reference count nor taking the bus's rwsem. Be sure that |
169 | * those are accounted for before calling this function. |
170 | */ |
171 | void device_release_driver(struct device * dev) |
172 | { |
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173 | struct device_driver * drv = dev->driver; |
174 | |
175 | if (!drv) |
176 | return; |
177 | |
178 | sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj)); |
179 | sysfs_remove_link(&dev->kobj, "driver"); |
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180 | klist_del(&dev->knode_driver); |
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181 | |
182 | down(&dev->sem); |
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183 | if (drv->remove) |
184 | drv->remove(dev); |
185 | dev->driver = NULL; |
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186 | up(&dev->sem); |
187 | } |
188 | |
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189 | static int __remove_driver(struct device * dev, void * unused) |
190 | { |
191 | device_release_driver(dev); |
192 | return 0; |
193 | } |
194 | |
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195 | /** |
196 | * driver_detach - detach driver from all devices it controls. |
197 | * @drv: driver. |
198 | */ |
199 | void driver_detach(struct device_driver * drv) |
200 | { |
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201 | driver_for_each_device(drv, NULL, NULL, __remove_driver); |
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202 | } |
203 | |
204 | |
205 | EXPORT_SYMBOL_GPL(driver_probe_device); |
206 | EXPORT_SYMBOL_GPL(device_bind_driver); |
207 | EXPORT_SYMBOL_GPL(device_release_driver); |
208 | EXPORT_SYMBOL_GPL(device_attach); |
209 | EXPORT_SYMBOL_GPL(driver_attach); |
210 | |