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 | 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 | */ |
48 | 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 | 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 | } |
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 | 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 | 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 | } |
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 | 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 | 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) && get_device(dev)) |
165 | break; |
166 | klist_iter_exit(i: &i); |
167 | 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 | int driver_create_file(struct device_driver *drv, |
177 | const struct driver_attribute *attr) |
178 | { |
179 | int error; |
180 | |
181 | if (drv) |
182 | error = sysfs_create_file(kobj: &drv->p->kobj, attr: &attr->attr); |
183 | else |
184 | error = -EINVAL; |
185 | 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 | void driver_remove_file(struct device_driver *drv, |
195 | const struct driver_attribute *attr) |
196 | { |
197 | if (drv) |
198 | sysfs_remove_file(kobj: &drv->p->kobj, attr: &attr->attr); |
199 | } |
200 | EXPORT_SYMBOL_GPL(driver_remove_file); |
201 | |
202 | int driver_add_groups(struct device_driver *drv, |
203 | const struct attribute_group **groups) |
204 | { |
205 | return sysfs_create_groups(kobj: &drv->p->kobj, groups); |
206 | } |
207 | |
208 | void driver_remove_groups(struct device_driver *drv, |
209 | const struct attribute_group **groups) |
210 | { |
211 | sysfs_remove_groups(kobj: &drv->p->kobj, groups); |
212 | } |
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 | int driver_register(struct device_driver *drv) |
223 | { |
224 | int ret; |
225 | struct device_driver *other; |
226 | |
227 | if (!bus_is_registered(bus: drv->bus)) { |
228 | 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 | return -EINVAL; |
231 | } |
232 | |
233 | if ((drv->bus->probe && drv->probe) || |
234 | (drv->bus->remove && drv->remove) || |
235 | (drv->bus->shutdown && drv->shutdown)) |
236 | pr_warn("Driver '%s' needs updating - please use " |
237 | "bus_type methods\n" , drv->name); |
238 | |
239 | other = driver_find(name: drv->name, bus: drv->bus); |
240 | if (other) { |
241 | pr_err("Error: Driver '%s' is already registered, " |
242 | "aborting...\n" , drv->name); |
243 | return -EBUSY; |
244 | } |
245 | |
246 | ret = bus_add_driver(drv); |
247 | if (ret) |
248 | return ret; |
249 | ret = driver_add_groups(drv, groups: drv->groups); |
250 | if (ret) { |
251 | bus_remove_driver(drv); |
252 | return ret; |
253 | } |
254 | kobject_uevent(kobj: &drv->p->kobj, action: KOBJ_ADD); |
255 | deferred_probe_extend_timeout(); |
256 | |
257 | 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 | void driver_unregister(struct device_driver *drv) |
268 | { |
269 | if (!drv || !drv->p) { |
270 | WARN(1, "Unexpected driver unregister!\n" ); |
271 | return; |
272 | } |
273 | driver_remove_groups(drv, groups: drv->groups); |
274 | bus_remove_driver(drv); |
275 | } |
276 | EXPORT_SYMBOL_GPL(driver_unregister); |
277 | |