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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 <linux/sysfs.h>
19#include "base.h"
20
21static struct device *next_device(struct klist_iter *i)
22{
23 struct klist_node *n = klist_next(i);
24 struct device *dev = NULL;
25 struct device_private *dev_prv;
26
27 if (n) {
28 dev_prv = to_device_private_driver(n);
29 dev = dev_prv->device;
30 }
31 return dev;
32}
33
34/**
35 * driver_for_each_device - Iterator for devices bound to a driver.
36 * @drv: Driver we're iterating.
37 * @start: Device to begin with
38 * @data: Data to pass to the callback.
39 * @fn: Function to call for each device.
40 *
41 * Iterate over the @drv's list of devices calling @fn for each one.
42 */
43int driver_for_each_device(struct device_driver *drv, struct device *start,
44 void *data, int (*fn)(struct device *, void *))
45{
46 struct klist_iter i;
47 struct device *dev;
48 int error = 0;
49
50 if (!drv)
51 return -EINVAL;
52
53 klist_iter_init_node(&drv->p->klist_devices, &i,
54 start ? &start->p->knode_driver : NULL);
55 while ((dev = next_device(&i)) && !error)
56 error = fn(dev, data);
57 klist_iter_exit(&i);
58 return error;
59}
60EXPORT_SYMBOL_GPL(driver_for_each_device);
61
62/**
63 * driver_find_device - device iterator for locating a particular device.
64 * @drv: The device's driver
65 * @start: Device to begin with
66 * @data: Data to pass to match function
67 * @match: Callback function to check device
68 *
69 * This is similar to the driver_for_each_device() function above, but
70 * it returns a reference to a device that is 'found' for later use, as
71 * determined by the @match callback.
72 *
73 * The callback should return 0 if the device doesn't match and non-zero
74 * if it does. If the callback returns non-zero, this function will
75 * return to the caller and not iterate over any more devices.
76 */
77struct device *driver_find_device(struct device_driver *drv,
78 struct device *start, void *data,
79 int (*match)(struct device *dev, void *data))
80{
81 struct klist_iter i;
82 struct device *dev;
83
84 if (!drv || !drv->p)
85 return NULL;
86
87 klist_iter_init_node(&drv->p->klist_devices, &i,
88 (start ? &start->p->knode_driver : NULL));
89 while ((dev = next_device(&i)))
90 if (match(dev, data) && get_device(dev))
91 break;
92 klist_iter_exit(&i);
93 return dev;
94}
95EXPORT_SYMBOL_GPL(driver_find_device);
96
97/**
98 * driver_create_file - create sysfs file for driver.
99 * @drv: driver.
100 * @attr: driver attribute descriptor.
101 */
102int driver_create_file(struct device_driver *drv,
103 const struct driver_attribute *attr)
104{
105 int error;
106 if (drv)
107 error = sysfs_create_file(&drv->p->kobj, &attr->attr);
108 else
109 error = -EINVAL;
110 return error;
111}
112EXPORT_SYMBOL_GPL(driver_create_file);
113
114/**
115 * driver_remove_file - remove sysfs file for driver.
116 * @drv: driver.
117 * @attr: driver attribute descriptor.
118 */
119void driver_remove_file(struct device_driver *drv,
120 const struct driver_attribute *attr)
121{
122 if (drv)
123 sysfs_remove_file(&drv->p->kobj, &attr->attr);
124}
125EXPORT_SYMBOL_GPL(driver_remove_file);
126
127int driver_add_groups(struct device_driver *drv,
128 const struct attribute_group **groups)
129{
130 return sysfs_create_groups(&drv->p->kobj, groups);
131}
132
133void driver_remove_groups(struct device_driver *drv,
134 const struct attribute_group **groups)
135{
136 sysfs_remove_groups(&drv->p->kobj, groups);
137}
138
139/**
140 * driver_register - register driver with bus
141 * @drv: driver to register
142 *
143 * We pass off most of the work to the bus_add_driver() call,
144 * since most of the things we have to do deal with the bus
145 * structures.
146 */
147int driver_register(struct device_driver *drv)
148{
149 int ret;
150 struct device_driver *other;
151
152 BUG_ON(!drv->bus->p);
153
154 if ((drv->bus->probe && drv->probe) ||
155 (drv->bus->remove && drv->remove) ||
156 (drv->bus->shutdown && drv->shutdown))
157 printk(KERN_WARNING "Driver '%s' needs updating - please use "
158 "bus_type methods\n", drv->name);
159
160 other = driver_find(drv->name, drv->bus);
161 if (other) {
162 printk(KERN_ERR "Error: Driver '%s' is already registered, "
163 "aborting...\n", drv->name);
164 return -EBUSY;
165 }
166
167 ret = bus_add_driver(drv);
168 if (ret)
169 return ret;
170 ret = driver_add_groups(drv, drv->groups);
171 if (ret) {
172 bus_remove_driver(drv);
173 return ret;
174 }
175 kobject_uevent(&drv->p->kobj, KOBJ_ADD);
176
177 return ret;
178}
179EXPORT_SYMBOL_GPL(driver_register);
180
181/**
182 * driver_unregister - remove driver from system.
183 * @drv: driver.
184 *
185 * Again, we pass off most of the work to the bus-level call.
186 */
187void driver_unregister(struct device_driver *drv)
188{
189 if (!drv || !drv->p) {
190 WARN(1, "Unexpected driver unregister!\n");
191 return;
192 }
193 driver_remove_groups(drv, drv->groups);
194 bus_remove_driver(drv);
195}
196EXPORT_SYMBOL_GPL(driver_unregister);
197
198/**
199 * driver_find - locate driver on a bus by its name.
200 * @name: name of the driver.
201 * @bus: bus to scan for the driver.
202 *
203 * Call kset_find_obj() to iterate over list of drivers on
204 * a bus to find driver by name. Return driver if found.
205 *
206 * This routine provides no locking to prevent the driver it returns
207 * from being unregistered or unloaded while the caller is using it.
208 * The caller is responsible for preventing this.
209 */
210struct device_driver *driver_find(const char *name, struct bus_type *bus)
211{
212 struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
213 struct driver_private *priv;
214
215 if (k) {
216 /* Drop reference added by kset_find_obj() */
217 kobject_put(k);
218 priv = to_driver(k);
219 return priv->driver;
220 }
221 return NULL;
222}
223EXPORT_SYMBOL_GPL(driver_find);
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(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(new);
98 *override = NULL;
99 }
100 device_unlock(dev);
101
102 kfree(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, 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(&drv->p->klist_devices, &i,
128 start ? &start->p->knode_driver : NULL);
129 while (!error && (dev = next_device(&i)))
130 error = fn(dev, data);
131 klist_iter_exit(&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(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(&drv->p->klist_devices, &i,
162 (start ? &start->p->knode_driver : NULL));
163 while ((dev = next_device(&i)))
164 if (match(dev, data) && get_device(dev))
165 break;
166 klist_iter_exit(&i);
167 return dev;
168}
169EXPORT_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 */
176int 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(&drv->p->kobj, &attr->attr);
183 else
184 error = -EINVAL;
185 return error;
186}
187EXPORT_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 */
194void driver_remove_file(struct device_driver *drv,
195 const struct driver_attribute *attr)
196{
197 if (drv)
198 sysfs_remove_file(&drv->p->kobj, &attr->attr);
199}
200EXPORT_SYMBOL_GPL(driver_remove_file);
201
202int driver_add_groups(struct device_driver *drv,
203 const struct attribute_group **groups)
204{
205 return sysfs_create_groups(&drv->p->kobj, groups);
206}
207
208void driver_remove_groups(struct device_driver *drv,
209 const struct attribute_group **groups)
210{
211 sysfs_remove_groups(&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 */
222int driver_register(struct device_driver *drv)
223{
224 int ret;
225 struct device_driver *other;
226
227 if (!drv->bus->p) {
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(drv->name, 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, drv->groups);
250 if (ret) {
251 bus_remove_driver(drv);
252 return ret;
253 }
254 kobject_uevent(&drv->p->kobj, KOBJ_ADD);
255 deferred_probe_extend_timeout();
256
257 return ret;
258}
259EXPORT_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 */
267void 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, drv->groups);
274 bus_remove_driver(drv);
275}
276EXPORT_SYMBOL_GPL(driver_unregister);
277
278/**
279 * driver_find - locate driver on a bus by its name.
280 * @name: name of the driver.
281 * @bus: bus to scan for the driver.
282 *
283 * Call kset_find_obj() to iterate over list of drivers on
284 * a bus to find driver by name. Return driver if found.
285 *
286 * This routine provides no locking to prevent the driver it returns
287 * from being unregistered or unloaded while the caller is using it.
288 * The caller is responsible for preventing this.
289 */
290struct device_driver *driver_find(const char *name, struct bus_type *bus)
291{
292 struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
293 struct driver_private *priv;
294
295 if (k) {
296 /* Drop reference added by kset_find_obj() */
297 kobject_put(k);
298 priv = to_driver(k);
299 return priv->driver;
300 }
301 return NULL;
302}
303EXPORT_SYMBOL_GPL(driver_find);