1// SPDX-License-Identifier: GPL-2.0
2/*
3 * driver.c - centralized device driver management
4 *
5 * Copyright (c) 2002-3 Patrick Mochel
6 * Copyright (c) 2002-3 Open Source Development Labs
7 * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
8 * Copyright (c) 2007 Novell Inc.
9 */
10
11#include <linux/device/driver.h>
12#include <linux/device.h>
13#include <linux/module.h>
14#include <linux/errno.h>
15#include <linux/slab.h>
16#include <linux/string.h>
17#include <linux/sysfs.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_set_override() - Helper to set or clear driver override.
35 * @dev: Device to change
36 * @override: Address of string to change (e.g. &device->driver_override);
37 * The contents will be freed and hold newly allocated override.
38 * @s: NUL-terminated string, new driver name to force a match, pass empty
39 * string to clear it ("" or "\n", where the latter is only for sysfs
40 * interface).
41 * @len: length of @s
42 *
43 * Helper to set or clear driver override in a device, intended for the cases
44 * when the driver_override field is allocated by driver/bus code.
45 *
46 * Returns: 0 on success or a negative error code on failure.
47 */
48int driver_set_override(struct device *dev, const char **override,
49 const char *s, size_t len)
50{
51 const char *new, *old;
52 char *cp;
53
54 if (!override || !s)
55 return -EINVAL;
56
57 /*
58 * The stored value will be used in sysfs show callback (sysfs_emit()),
59 * which has a length limit of PAGE_SIZE and adds a trailing newline.
60 * Thus we can store one character less to avoid truncation during sysfs
61 * show.
62 */
63 if (len >= (PAGE_SIZE - 1))
64 return -EINVAL;
65
66 /*
67 * Compute the real length of the string in case userspace sends us a
68 * bunch of \0 characters like python likes to do.
69 */
70 len = strlen(s);
71
72 if (!len) {
73 /* Empty string passed - clear override */
74 device_lock(dev);
75 old = *override;
76 *override = NULL;
77 device_unlock(dev);
78 kfree(objp: old);
79
80 return 0;
81 }
82
83 cp = strnchr(s, len, '\n');
84 if (cp)
85 len = cp - s;
86
87 new = kstrndup(s, len, GFP_KERNEL);
88 if (!new)
89 return -ENOMEM;
90
91 device_lock(dev);
92 old = *override;
93 if (cp != s) {
94 *override = new;
95 } else {
96 /* "\n" passed - clear override */
97 kfree(objp: new);
98 *override = NULL;
99 }
100 device_unlock(dev);
101
102 kfree(objp: old);
103
104 return 0;
105}
106EXPORT_SYMBOL_GPL(driver_set_override);
107
108/**
109 * driver_for_each_device - Iterator for devices bound to a driver.
110 * @drv: Driver we're iterating.
111 * @start: Device to begin with
112 * @data: Data to pass to the callback.
113 * @fn: Function to call for each device.
114 *
115 * Iterate over the @drv's list of devices calling @fn for each one.
116 */
117int driver_for_each_device(struct device_driver *drv, struct device *start,
118 void *data, device_iter_t fn)
119{
120 struct klist_iter i;
121 struct device *dev;
122 int error = 0;
123
124 if (!drv)
125 return -EINVAL;
126
127 klist_iter_init_node(k: &drv->p->klist_devices, i: &i,
128 n: start ? &start->p->knode_driver : NULL);
129 while (!error && (dev = next_device(i: &i)))
130 error = fn(dev, data);
131 klist_iter_exit(i: &i);
132 return error;
133}
134EXPORT_SYMBOL_GPL(driver_for_each_device);
135
136/**
137 * driver_find_device - device iterator for locating a particular device.
138 * @drv: The device's driver
139 * @start: Device to begin with
140 * @data: Data to pass to match function
141 * @match: Callback function to check device
142 *
143 * This is similar to the driver_for_each_device() function above, but
144 * it returns a reference to a device that is 'found' for later use, as
145 * determined by the @match callback.
146 *
147 * The callback should return 0 if the device doesn't match and non-zero
148 * if it does. If the callback returns non-zero, this function will
149 * return to the caller and not iterate over any more devices.
150 */
151struct device *driver_find_device(const struct device_driver *drv,
152 struct device *start, const void *data,
153 device_match_t match)
154{
155 struct klist_iter i;
156 struct device *dev;
157
158 if (!drv || !drv->p)
159 return NULL;
160
161 klist_iter_init_node(k: &drv->p->klist_devices, i: &i,
162 n: (start ? &start->p->knode_driver : NULL));
163 while ((dev = next_device(i: &i))) {
164 if (match(dev, data)) {
165 get_device(dev);
166 break;
167 }
168 }
169 klist_iter_exit(i: &i);
170 return dev;
171}
172EXPORT_SYMBOL_GPL(driver_find_device);
173
174/**
175 * driver_create_file - create sysfs file for driver.
176 * @drv: driver.
177 * @attr: driver attribute descriptor.
178 */
179int driver_create_file(const struct device_driver *drv,
180 const struct driver_attribute *attr)
181{
182 int error;
183
184 if (drv)
185 error = sysfs_create_file(kobj: &drv->p->kobj, attr: &attr->attr);
186 else
187 error = -EINVAL;
188 return error;
189}
190EXPORT_SYMBOL_GPL(driver_create_file);
191
192/**
193 * driver_remove_file - remove sysfs file for driver.
194 * @drv: driver.
195 * @attr: driver attribute descriptor.
196 */
197void driver_remove_file(const struct device_driver *drv,
198 const struct driver_attribute *attr)
199{
200 if (drv)
201 sysfs_remove_file(kobj: &drv->p->kobj, attr: &attr->attr);
202}
203EXPORT_SYMBOL_GPL(driver_remove_file);
204
205int driver_add_groups(const struct device_driver *drv,
206 const struct attribute_group **groups)
207{
208 return sysfs_create_groups(kobj: &drv->p->kobj, groups);
209}
210
211void driver_remove_groups(const struct device_driver *drv,
212 const struct attribute_group **groups)
213{
214 sysfs_remove_groups(kobj: &drv->p->kobj, groups);
215}
216
217/**
218 * driver_register - register driver with bus
219 * @drv: driver to register
220 *
221 * We pass off most of the work to the bus_add_driver() call,
222 * since most of the things we have to do deal with the bus
223 * structures.
224 */
225int driver_register(struct device_driver *drv)
226{
227 int ret;
228 struct device_driver *other;
229
230 if (!bus_is_registered(bus: drv->bus)) {
231 pr_err("Driver '%s' was unable to register with bus_type '%s' because the bus was not initialized.\n",
232 drv->name, drv->bus->name);
233 return -EINVAL;
234 }
235
236 if ((drv->bus->probe && drv->probe) ||
237 (drv->bus->remove && drv->remove) ||
238 (drv->bus->shutdown && drv->shutdown))
239 pr_warn("Driver '%s' needs updating - please use "
240 "bus_type methods\n", drv->name);
241
242 other = driver_find(name: drv->name, bus: drv->bus);
243 if (other) {
244 pr_err("Error: Driver '%s' is already registered, "
245 "aborting...\n", drv->name);
246 return -EBUSY;
247 }
248
249 ret = bus_add_driver(drv);
250 if (ret)
251 return ret;
252 ret = driver_add_groups(drv, groups: drv->groups);
253 if (ret) {
254 bus_remove_driver(drv);
255 return ret;
256 }
257 kobject_uevent(kobj: &drv->p->kobj, action: KOBJ_ADD);
258 deferred_probe_extend_timeout();
259
260 return ret;
261}
262EXPORT_SYMBOL_GPL(driver_register);
263
264/**
265 * driver_unregister - remove driver from system.
266 * @drv: driver.
267 *
268 * Again, we pass off most of the work to the bus-level call.
269 */
270void driver_unregister(struct device_driver *drv)
271{
272 if (!drv || !drv->p) {
273 WARN(1, "Unexpected driver unregister!\n");
274 return;
275 }
276 driver_remove_groups(drv, groups: drv->groups);
277 bus_remove_driver(drv);
278}
279EXPORT_SYMBOL_GPL(driver_unregister);
280

source code of linux/drivers/base/driver.c