개념 설명 전체 · v6.6 / drivers/base/driver.c
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(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 } 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(&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 } 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(&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 } 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(&drv->p->kobj, &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(&drv->p->kobj, &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(&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(&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(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(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 } 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, drv->groups); 274 bus_remove_driver(drv); 275 } 276 EXPORT_SYMBOL_GPL(driver_unregister);