projects/linux·blob v2.6.21 · refs

221 lines · 5.6 KiB

1/*
2 * driver.c - centralized device driver management
3 *
4 * Copyright (c) 2002-3 Patrick Mochel
5 * Copyright (c) 2002-3 Open Source Development Labs
6 *
7 * This file is released under the GPLv2
8 *
9 */
10
11#include <linux/device.h>
12#include <linux/module.h>
13#include <linux/errno.h>
14#include <linux/string.h>
15#include "base.h"
16
17#define to_dev(node) container_of(node, struct device, driver_list)
18#define to_drv(obj) container_of(obj, struct device_driver, kobj)
19
20
21static struct device * next_device(struct klist_iter * i)
22{
23 struct klist_node * n = klist_next(i);
24 return n ? container_of(n, struct device, knode_driver) : NULL;
25}
26
27/**
28 * driver_for_each_device - Iterator for devices bound to a driver.
29 * @drv: Driver we're iterating.
30 * @start: Device to begin with
31 * @data: Data to pass to the callback.
32 * @fn: Function to call for each device.
33 *
34 * Iterate over the @drv's list of devices calling @fn for each one.
35 */
36
37int driver_for_each_device(struct device_driver * drv, struct device * start,
38 void * data, int (*fn)(struct device *, void *))
39{
40 struct klist_iter i;
41 struct device * dev;
42 int error = 0;
43
44 if (!drv)
45 return -EINVAL;
46
47 klist_iter_init_node(&drv->klist_devices, &i,
48 start ? &start->knode_driver : NULL);
49 while ((dev = next_device(&i)) && !error)
50 error = fn(dev, data);
51 klist_iter_exit(&i);
52 return error;
53}
54
55EXPORT_SYMBOL_GPL(driver_for_each_device);
56
57
58/**
59 * driver_find_device - device iterator for locating a particular device.
60 * @drv: The device's driver
61 * @start: Device to begin with
62 * @data: Data to pass to match function
63 * @match: Callback function to check device
64 *
65 * This is similar to the driver_for_each_device() function above, but
66 * it returns a reference to a device that is 'found' for later use, as
67 * determined by the @match callback.
68 *
69 * The callback should return 0 if the device doesn't match and non-zero
70 * if it does. If the callback returns non-zero, this function will
71 * return to the caller and not iterate over any more devices.
72 */
73struct device * driver_find_device(struct device_driver *drv,
74 struct device * start, void * data,
75 int (*match)(struct device *, void *))
76{
77 struct klist_iter i;
78 struct device *dev;
79
80 if (!drv)
81 return NULL;
82
83 klist_iter_init_node(&drv->klist_devices, &i,
84 (start ? &start->knode_driver : NULL));
85 while ((dev = next_device(&i)))
86 if (match(dev, data) && get_device(dev))
87 break;
88 klist_iter_exit(&i);
89 return dev;
90}
91EXPORT_SYMBOL_GPL(driver_find_device);
92
93/**
94 * driver_create_file - create sysfs file for driver.
95 * @drv: driver.
96 * @attr: driver attribute descriptor.
97 */
98
99int driver_create_file(struct device_driver * drv, struct driver_attribute * attr)
100{
101 int error;
102 if (get_driver(drv)) {
103 error = sysfs_create_file(&drv->kobj, &attr->attr);
104 put_driver(drv);
105 } else
106 error = -EINVAL;
107 return error;
108}
109
110
111/**
112 * driver_remove_file - remove sysfs file for driver.
113 * @drv: driver.
114 * @attr: driver attribute descriptor.
115 */
116
117void driver_remove_file(struct device_driver * drv, struct driver_attribute * attr)
118{
119 if (get_driver(drv)) {
120 sysfs_remove_file(&drv->kobj, &attr->attr);
121 put_driver(drv);
122 }
123}
124
125
126/**
127 * get_driver - increment driver reference count.
128 * @drv: driver.
129 */
130struct device_driver * get_driver(struct device_driver * drv)
131{
132 return drv ? to_drv(kobject_get(&drv->kobj)) : NULL;
133}
134
135
136/**
137 * put_driver - decrement driver's refcount.
138 * @drv: driver.
139 */
140void put_driver(struct device_driver * drv)
141{
142 kobject_put(&drv->kobj);
143}
144
145/**
146 * driver_register - register driver with bus
147 * @drv: driver to register
148 *
149 * We pass off most of the work to the bus_add_driver() call,
150 * since most of the things we have to do deal with the bus
151 * structures.
152 *
153 * The one interesting aspect is that we setup @drv->unloaded
154 * as a completion that gets complete when the driver reference
155 * count reaches 0.
156 */
157int driver_register(struct device_driver * drv)
158{
159 if ((drv->bus->probe && drv->probe) ||
160 (drv->bus->remove && drv->remove) ||
161 (drv->bus->shutdown && drv->shutdown)) {
162 printk(KERN_WARNING "Driver '%s' needs updating - please use bus_type methods\n", drv->name);
163 }
164 klist_init(&drv->klist_devices, NULL, NULL);
165 init_completion(&drv->unloaded);
166 return bus_add_driver(drv);
167}
168
169
170/**
171 * driver_unregister - remove driver from system.
172 * @drv: driver.
173 *
174 * Again, we pass off most of the work to the bus-level call.
175 *
176 * Though, once that is done, we wait until @drv->unloaded is completed.
177 * This will block until the driver refcount reaches 0, and it is
178 * released. Only modular drivers will call this function, and we
179 * have to guarantee that it won't complete, letting the driver
180 * unload until all references are gone.
181 */
182
183void driver_unregister(struct device_driver * drv)
184{
185 bus_remove_driver(drv);
186 /*
187 * If the driver is a module, we are probably in
188 * the module unload path, and we want to wait
189 * for everything to unload before we can actually
190 * finish the unload.
191 */
192 if (drv->owner)
193 wait_for_completion(&drv->unloaded);
194}
195
196/**
197 * driver_find - locate driver on a bus by its name.
198 * @name: name of the driver.
199 * @bus: bus to scan for the driver.
200 *
201 * Call kset_find_obj() to iterate over list of drivers on
202 * a bus to find driver by name. Return driver if found.
203 *
204 * Note that kset_find_obj increments driver's reference count.
205 */
206struct device_driver *driver_find(const char *name, struct bus_type *bus)
207{
208 struct kobject *k = kset_find_obj(&bus->drivers, name);
209 if (k)
210 return to_drv(k);
211 return NULL;
212}
213
214EXPORT_SYMBOL_GPL(driver_register);
215EXPORT_SYMBOL_GPL(driver_unregister);
216EXPORT_SYMBOL_GPL(get_driver);
217EXPORT_SYMBOL_GPL(put_driver);
218EXPORT_SYMBOL_GPL(driver_find);
219
220EXPORT_SYMBOL_GPL(driver_create_file);
221EXPORT_SYMBOL_GPL(driver_remove_file);