Root/drivers/base/driver.c

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 * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
7 * Copyright (c) 2007 Novell Inc.
8 *
9 * This file is released under the GPLv2
10 *
11 */
12
13#include <linux/device.h>
14#include <linux/module.h>
15#include <linux/errno.h>
16#include <linux/slab.h>
17#include <linux/string.h>
18#include "base.h"
19
20static struct device *next_device(struct klist_iter *i)
21{
22    struct klist_node *n = klist_next(i);
23    struct device *dev = NULL;
24    struct device_private *dev_prv;
25
26    if (n) {
27        dev_prv = to_device_private_driver(n);
28        dev = dev_prv->device;
29    }
30    return dev;
31}
32
33/**
34 * driver_for_each_device - Iterator for devices bound to a driver.
35 * @drv: Driver we're iterating.
36 * @start: Device to begin with
37 * @data: Data to pass to the callback.
38 * @fn: Function to call for each device.
39 *
40 * Iterate over the @drv's list of devices calling @fn for each one.
41 */
42int driver_for_each_device(struct device_driver *drv, struct device *start,
43               void *data, int (*fn)(struct device *, void *))
44{
45    struct klist_iter i;
46    struct device *dev;
47    int error = 0;
48
49    if (!drv)
50        return -EINVAL;
51
52    klist_iter_init_node(&drv->p->klist_devices, &i,
53                 start ? &start->p->knode_driver : NULL);
54    while ((dev = next_device(&i)) && !error)
55        error = fn(dev, data);
56    klist_iter_exit(&i);
57    return error;
58}
59EXPORT_SYMBOL_GPL(driver_for_each_device);
60
61/**
62 * driver_find_device - device iterator for locating a particular device.
63 * @drv: The device's driver
64 * @start: Device to begin with
65 * @data: Data to pass to match function
66 * @match: Callback function to check device
67 *
68 * This is similar to the driver_for_each_device() function above, but
69 * it returns a reference to a device that is 'found' for later use, as
70 * determined by the @match callback.
71 *
72 * The callback should return 0 if the device doesn't match and non-zero
73 * if it does. If the callback returns non-zero, this function will
74 * return to the caller and not iterate over any more devices.
75 */
76struct device *driver_find_device(struct device_driver *drv,
77                  struct device *start, void *data,
78                  int (*match)(struct device *dev, void *data))
79{
80    struct klist_iter i;
81    struct device *dev;
82
83    if (!drv || !drv->p)
84        return NULL;
85
86    klist_iter_init_node(&drv->p->klist_devices, &i,
87                 (start ? &start->p->knode_driver : NULL));
88    while ((dev = next_device(&i)))
89        if (match(dev, data) && get_device(dev))
90            break;
91    klist_iter_exit(&i);
92    return dev;
93}
94EXPORT_SYMBOL_GPL(driver_find_device);
95
96/**
97 * driver_create_file - create sysfs file for driver.
98 * @drv: driver.
99 * @attr: driver attribute descriptor.
100 */
101int driver_create_file(struct device_driver *drv,
102               const struct driver_attribute *attr)
103{
104    int error;
105    if (drv)
106        error = sysfs_create_file(&drv->p->kobj, &attr->attr);
107    else
108        error = -EINVAL;
109    return error;
110}
111EXPORT_SYMBOL_GPL(driver_create_file);
112
113/**
114 * driver_remove_file - remove sysfs file for driver.
115 * @drv: driver.
116 * @attr: driver attribute descriptor.
117 */
118void driver_remove_file(struct device_driver *drv,
119            const struct driver_attribute *attr)
120{
121    if (drv)
122        sysfs_remove_file(&drv->p->kobj, &attr->attr);
123}
124EXPORT_SYMBOL_GPL(driver_remove_file);
125
126static int driver_add_groups(struct device_driver *drv,
127                 const struct attribute_group **groups)
128{
129    int error = 0;
130    int i;
131
132    if (groups) {
133        for (i = 0; groups[i]; i++) {
134            error = sysfs_create_group(&drv->p->kobj, groups[i]);
135            if (error) {
136                while (--i >= 0)
137                    sysfs_remove_group(&drv->p->kobj,
138                               groups[i]);
139                break;
140            }
141        }
142    }
143    return error;
144}
145
146static void driver_remove_groups(struct device_driver *drv,
147                 const struct attribute_group **groups)
148{
149    int i;
150
151    if (groups)
152        for (i = 0; groups[i]; i++)
153            sysfs_remove_group(&drv->p->kobj, groups[i]);
154}
155
156/**
157 * driver_register - register driver with bus
158 * @drv: driver to register
159 *
160 * We pass off most of the work to the bus_add_driver() call,
161 * since most of the things we have to do deal with the bus
162 * structures.
163 */
164int driver_register(struct device_driver *drv)
165{
166    int ret;
167    struct device_driver *other;
168
169    BUG_ON(!drv->bus->p);
170
171    if ((drv->bus->probe && drv->probe) ||
172        (drv->bus->remove && drv->remove) ||
173        (drv->bus->shutdown && drv->shutdown))
174        printk(KERN_WARNING "Driver '%s' needs updating - please use "
175            "bus_type methods\n", drv->name);
176
177    other = driver_find(drv->name, drv->bus);
178    if (other) {
179        printk(KERN_ERR "Error: Driver '%s' is already registered, "
180            "aborting...\n", drv->name);
181        return -EBUSY;
182    }
183
184    ret = bus_add_driver(drv);
185    if (ret)
186        return ret;
187    ret = driver_add_groups(drv, drv->groups);
188    if (ret) {
189        bus_remove_driver(drv);
190        return ret;
191    }
192    kobject_uevent(&drv->p->kobj, KOBJ_ADD);
193
194    return ret;
195}
196EXPORT_SYMBOL_GPL(driver_register);
197
198/**
199 * driver_unregister - remove driver from system.
200 * @drv: driver.
201 *
202 * Again, we pass off most of the work to the bus-level call.
203 */
204void driver_unregister(struct device_driver *drv)
205{
206    if (!drv || !drv->p) {
207        WARN(1, "Unexpected driver unregister!\n");
208        return;
209    }
210    driver_remove_groups(drv, drv->groups);
211    bus_remove_driver(drv);
212}
213EXPORT_SYMBOL_GPL(driver_unregister);
214
215/**
216 * driver_find - locate driver on a bus by its name.
217 * @name: name of the driver.
218 * @bus: bus to scan for the driver.
219 *
220 * Call kset_find_obj() to iterate over list of drivers on
221 * a bus to find driver by name. Return driver if found.
222 *
223 * This routine provides no locking to prevent the driver it returns
224 * from being unregistered or unloaded while the caller is using it.
225 * The caller is responsible for preventing this.
226 */
227struct device_driver *driver_find(const char *name, struct bus_type *bus)
228{
229    struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
230    struct driver_private *priv;
231
232    if (k) {
233        /* Drop reference added by kset_find_obj() */
234        kobject_put(k);
235        priv = to_driver(k);
236        return priv->driver;
237    }
238    return NULL;
239}
240EXPORT_SYMBOL_GPL(driver_find);
241

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