Line data Source code
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 :
20 : static struct device *next_device(struct klist_iter *i)
21 : {
22 0 : struct klist_node *n = klist_next(i);
23 0 : struct device *dev = NULL;
24 : struct device_private *dev_prv;
25 :
26 0 : if (n) {
27 0 : dev_prv = to_device_private_driver(n);
28 0 : 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 : */
48 0 : int 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 0 : 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 0 : 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 0 : len = strlen(s);
71 :
72 0 : if (!len) {
73 : /* Empty string passed - clear override */
74 0 : device_lock(dev);
75 0 : old = *override;
76 0 : *override = NULL;
77 0 : device_unlock(dev);
78 0 : kfree(old);
79 :
80 0 : return 0;
81 : }
82 :
83 0 : cp = strnchr(s, len, '\n');
84 0 : if (cp)
85 0 : len = cp - s;
86 :
87 0 : new = kstrndup(s, len, GFP_KERNEL);
88 0 : if (!new)
89 : return -ENOMEM;
90 :
91 0 : device_lock(dev);
92 0 : old = *override;
93 0 : if (cp != s) {
94 0 : *override = new;
95 : } else {
96 : /* "\n" passed - clear override */
97 0 : kfree(new);
98 0 : *override = NULL;
99 : }
100 0 : device_unlock(dev);
101 :
102 0 : kfree(old);
103 :
104 0 : return 0;
105 : }
106 : EXPORT_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 : */
117 0 : int driver_for_each_device(struct device_driver *drv, struct device *start,
118 : void *data, int (*fn)(struct device *, void *))
119 : {
120 : struct klist_iter i;
121 : struct device *dev;
122 0 : int error = 0;
123 :
124 0 : if (!drv)
125 : return -EINVAL;
126 :
127 0 : klist_iter_init_node(&drv->p->klist_devices, &i,
128 0 : start ? &start->p->knode_driver : NULL);
129 0 : while (!error && (dev = next_device(&i)))
130 0 : error = fn(dev, data);
131 0 : klist_iter_exit(&i);
132 0 : return error;
133 : }
134 : EXPORT_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 : */
151 0 : struct device *driver_find_device(struct device_driver *drv,
152 : struct device *start, const void *data,
153 : int (*match)(struct device *dev, const void *data))
154 : {
155 : struct klist_iter i;
156 : struct device *dev;
157 :
158 0 : if (!drv || !drv->p)
159 : return NULL;
160 :
161 0 : klist_iter_init_node(&drv->p->klist_devices, &i,
162 0 : (start ? &start->p->knode_driver : NULL));
163 0 : while ((dev = next_device(&i)))
164 0 : if (match(dev, data) && get_device(dev))
165 : break;
166 0 : klist_iter_exit(&i);
167 0 : return dev;
168 : }
169 : EXPORT_SYMBOL_GPL(driver_find_device);
170 :
171 : /**
172 : * driver_create_file - create sysfs file for driver.
173 : * @drv: driver.
174 : * @attr: driver attribute descriptor.
175 : */
176 63 : int driver_create_file(struct device_driver *drv,
177 : const struct driver_attribute *attr)
178 : {
179 : int error;
180 :
181 63 : if (drv)
182 126 : error = sysfs_create_file(&drv->p->kobj, &attr->attr);
183 : else
184 : error = -EINVAL;
185 63 : return error;
186 : }
187 : EXPORT_SYMBOL_GPL(driver_create_file);
188 :
189 : /**
190 : * driver_remove_file - remove sysfs file for driver.
191 : * @drv: driver.
192 : * @attr: driver attribute descriptor.
193 : */
194 18 : void driver_remove_file(struct device_driver *drv,
195 : const struct driver_attribute *attr)
196 : {
197 18 : if (drv)
198 18 : sysfs_remove_file(&drv->p->kobj, &attr->attr);
199 18 : }
200 : EXPORT_SYMBOL_GPL(driver_remove_file);
201 :
202 21 : int driver_add_groups(struct device_driver *drv,
203 : const struct attribute_group **groups)
204 : {
205 42 : return sysfs_create_groups(&drv->p->kobj, groups);
206 : }
207 :
208 6 : void driver_remove_groups(struct device_driver *drv,
209 : const struct attribute_group **groups)
210 : {
211 12 : sysfs_remove_groups(&drv->p->kobj, groups);
212 6 : }
213 :
214 : /**
215 : * driver_register - register driver with bus
216 : * @drv: driver to register
217 : *
218 : * We pass off most of the work to the bus_add_driver() call,
219 : * since most of the things we have to do deal with the bus
220 : * structures.
221 : */
222 21 : int driver_register(struct device_driver *drv)
223 : {
224 : int ret;
225 : struct device_driver *other;
226 :
227 21 : if (!bus_is_registered(drv->bus)) {
228 0 : pr_err("Driver '%s' was unable to register with bus_type '%s' because the bus was not initialized.\n",
229 : drv->name, drv->bus->name);
230 0 : return -EINVAL;
231 : }
232 :
233 42 : if ((drv->bus->probe && drv->probe) ||
234 63 : (drv->bus->remove && drv->remove) ||
235 31 : (drv->bus->shutdown && drv->shutdown))
236 0 : pr_warn("Driver '%s' needs updating - please use "
237 : "bus_type methods\n", drv->name);
238 :
239 21 : other = driver_find(drv->name, drv->bus);
240 21 : if (other) {
241 0 : pr_err("Error: Driver '%s' is already registered, "
242 : "aborting...\n", drv->name);
243 0 : return -EBUSY;
244 : }
245 :
246 21 : ret = bus_add_driver(drv);
247 21 : if (ret)
248 : return ret;
249 42 : ret = driver_add_groups(drv, drv->groups);
250 21 : if (ret) {
251 0 : bus_remove_driver(drv);
252 0 : return ret;
253 : }
254 21 : kobject_uevent(&drv->p->kobj, KOBJ_ADD);
255 21 : deferred_probe_extend_timeout();
256 :
257 21 : return ret;
258 : }
259 : EXPORT_SYMBOL_GPL(driver_register);
260 :
261 : /**
262 : * driver_unregister - remove driver from system.
263 : * @drv: driver.
264 : *
265 : * Again, we pass off most of the work to the bus-level call.
266 : */
267 6 : void driver_unregister(struct device_driver *drv)
268 : {
269 6 : if (!drv || !drv->p) {
270 0 : WARN(1, "Unexpected driver unregister!\n");
271 0 : return;
272 : }
273 12 : driver_remove_groups(drv, drv->groups);
274 6 : bus_remove_driver(drv);
275 : }
276 : EXPORT_SYMBOL_GPL(driver_unregister);
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