1 /* 2 * attribute_container.c - implementation of a simple container for classes 3 * 4 * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com> 5 * 6 * This file is licensed under GPLv2 7 * 8 * The basic idea here is to enable a device to be attached to an 9 * aritrary numer of classes without having to allocate storage for them. 10 * Instead, the contained classes select the devices they need to attach 11 * to via a matching function. 12 */ 13 14 #include <linux/attribute_container.h> 15 #include <linux/device.h> 16 #include <linux/kernel.h> 17 #include <linux/slab.h> 18 #include <linux/list.h> 19 #include <linux/module.h> 20 #include <linux/mutex.h> 21 22 #include "base.h" 23 24 /* This is a private structure used to tie the classdev and the 25 * container .. it should never be visible outside this file */ 26 struct internal_container { 27 struct klist_node node; 28 struct attribute_container *cont; 29 struct device classdev; 30 }; 31 32 static void internal_container_klist_get(struct klist_node *n) 33 { 34 struct internal_container *ic = 35 container_of(n, struct internal_container, node); 36 get_device(&ic->classdev); 37 } 38 39 static void internal_container_klist_put(struct klist_node *n) 40 { 41 struct internal_container *ic = 42 container_of(n, struct internal_container, node); 43 put_device(&ic->classdev); 44 } 45 46 47 /** 48 * attribute_container_classdev_to_container - given a classdev, return the container 49 * 50 * @classdev: the class device created by attribute_container_add_device. 51 * 52 * Returns the container associated with this classdev. 53 */ 54 struct attribute_container * 55 attribute_container_classdev_to_container(struct device *classdev) 56 { 57 struct internal_container *ic = 58 container_of(classdev, struct internal_container, classdev); 59 return ic->cont; 60 } 61 EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container); 62 63 static LIST_HEAD(attribute_container_list); 64 65 static DEFINE_MUTEX(attribute_container_mutex); 66 67 /** 68 * attribute_container_register - register an attribute container 69 * 70 * @cont: The container to register. This must be allocated by the 71 * callee and should also be zeroed by it. 72 */ 73 int 74 attribute_container_register(struct attribute_container *cont) 75 { 76 INIT_LIST_HEAD(&cont->node); 77 klist_init(&cont->containers, internal_container_klist_get, 78 internal_container_klist_put); 79 80 mutex_lock(&attribute_container_mutex); 81 list_add_tail(&cont->node, &attribute_container_list); 82 mutex_unlock(&attribute_container_mutex); 83 84 return 0; 85 } 86 EXPORT_SYMBOL_GPL(attribute_container_register); 87 88 /** 89 * attribute_container_unregister - remove a container registration 90 * 91 * @cont: previously registered container to remove 92 */ 93 int 94 attribute_container_unregister(struct attribute_container *cont) 95 { 96 int retval = -EBUSY; 97 98 mutex_lock(&attribute_container_mutex); 99 spin_lock(&cont->containers.k_lock); 100 if (!list_empty(&cont->containers.k_list)) 101 goto out; 102 retval = 0; 103 list_del(&cont->node); 104 out: 105 spin_unlock(&cont->containers.k_lock); 106 mutex_unlock(&attribute_container_mutex); 107 return retval; 108 109 } 110 EXPORT_SYMBOL_GPL(attribute_container_unregister); 111 112 /* private function used as class release */ 113 static void attribute_container_release(struct device *classdev) 114 { 115 struct internal_container *ic 116 = container_of(classdev, struct internal_container, classdev); 117 struct device *dev = classdev->parent; 118 119 kfree(ic); 120 put_device(dev); 121 } 122 123 /** 124 * attribute_container_add_device - see if any container is interested in dev 125 * 126 * @dev: device to add attributes to 127 * @fn: function to trigger addition of class device. 128 * 129 * This function allocates storage for the class device(s) to be 130 * attached to dev (one for each matching attribute_container). If no 131 * fn is provided, the code will simply register the class device via 132 * device_add. If a function is provided, it is expected to add 133 * the class device at the appropriate time. One of the things that 134 * might be necessary is to allocate and initialise the classdev and 135 * then add it a later time. To do this, call this routine for 136 * allocation and initialisation and then use 137 * attribute_container_device_trigger() to call device_add() on 138 * it. Note: after this, the class device contains a reference to dev 139 * which is not relinquished until the release of the classdev. 140 */ 141 void 142 attribute_container_add_device(struct device *dev, 143 int (*fn)(struct attribute_container *, 144 struct device *, 145 struct device *)) 146 { 147 struct attribute_container *cont; 148 149 mutex_lock(&attribute_container_mutex); 150 list_for_each_entry(cont, &attribute_container_list, node) { 151 struct internal_container *ic; 152 153 if (attribute_container_no_classdevs(cont)) 154 continue; 155 156 if (!cont->match(cont, dev)) 157 continue; 158 159 ic = kzalloc(sizeof(*ic), GFP_KERNEL); 160 if (!ic) { 161 dev_err(dev, "failed to allocate class container\n"); 162 continue; 163 } 164 165 ic->cont = cont; 166 device_initialize(&ic->classdev); 167 ic->classdev.parent = get_device(dev); 168 ic->classdev.class = cont->class; 169 cont->class->dev_release = attribute_container_release; 170 dev_set_name(&ic->classdev, "%s", dev_name(dev)); 171 if (fn) 172 fn(cont, dev, &ic->classdev); 173 else 174 attribute_container_add_class_device(&ic->classdev); 175 klist_add_tail(&ic->node, &cont->containers); 176 } 177 mutex_unlock(&attribute_container_mutex); 178 } 179 180 /* FIXME: can't break out of this unless klist_iter_exit is also 181 * called before doing the break 182 */ 183 #define klist_for_each_entry(pos, head, member, iter) \ 184 for (klist_iter_init(head, iter); (pos = ({ \ 185 struct klist_node *n = klist_next(iter); \ 186 n ? container_of(n, typeof(*pos), member) : \ 187 ({ klist_iter_exit(iter) ; NULL; }); \ 188 })) != NULL;) 189 190 191 /** 192 * attribute_container_remove_device - make device eligible for removal. 193 * 194 * @dev: The generic device 195 * @fn: A function to call to remove the device 196 * 197 * This routine triggers device removal. If fn is NULL, then it is 198 * simply done via device_unregister (note that if something 199 * still has a reference to the classdev, then the memory occupied 200 * will not be freed until the classdev is released). If you want a 201 * two phase release: remove from visibility and then delete the 202 * device, then you should use this routine with a fn that calls 203 * device_del() and then use attribute_container_device_trigger() 204 * to do the final put on the classdev. 205 */ 206 void 207 attribute_container_remove_device(struct device *dev, 208 void (*fn)(struct attribute_container *, 209 struct device *, 210 struct device *)) 211 { 212 struct attribute_container *cont; 213 214 mutex_lock(&attribute_container_mutex); 215 list_for_each_entry(cont, &attribute_container_list, node) { 216 struct internal_container *ic; 217 struct klist_iter iter; 218 219 if (attribute_container_no_classdevs(cont)) 220 continue; 221 222 if (!cont->match(cont, dev)) 223 continue; 224 225 klist_for_each_entry(ic, &cont->containers, node, &iter) { 226 if (dev != ic->classdev.parent) 227 continue; 228 klist_del(&ic->node); 229 if (fn) 230 fn(cont, dev, &ic->classdev); 231 else { 232 attribute_container_remove_attrs(&ic->classdev); 233 device_unregister(&ic->classdev); 234 } 235 } 236 } 237 mutex_unlock(&attribute_container_mutex); 238 } 239 240 /** 241 * attribute_container_device_trigger - execute a trigger for each matching classdev 242 * 243 * @dev: The generic device to run the trigger for 244 * @fn the function to execute for each classdev. 245 * 246 * This function is for executing a trigger when you need to know both 247 * the container and the classdev. If you only care about the 248 * container, then use attribute_container_trigger() instead. 249 */ 250 void 251 attribute_container_device_trigger(struct device *dev, 252 int (*fn)(struct attribute_container *, 253 struct device *, 254 struct device *)) 255 { 256 struct attribute_container *cont; 257 258 mutex_lock(&attribute_container_mutex); 259 list_for_each_entry(cont, &attribute_container_list, node) { 260 struct internal_container *ic; 261 struct klist_iter iter; 262 263 if (!cont->match(cont, dev)) 264 continue; 265 266 if (attribute_container_no_classdevs(cont)) { 267 fn(cont, dev, NULL); 268 continue; 269 } 270 271 klist_for_each_entry(ic, &cont->containers, node, &iter) { 272 if (dev == ic->classdev.parent) 273 fn(cont, dev, &ic->classdev); 274 } 275 } 276 mutex_unlock(&attribute_container_mutex); 277 } 278 279 /** 280 * attribute_container_trigger - trigger a function for each matching container 281 * 282 * @dev: The generic device to activate the trigger for 283 * @fn: the function to trigger 284 * 285 * This routine triggers a function that only needs to know the 286 * matching containers (not the classdev) associated with a device. 287 * It is more lightweight than attribute_container_device_trigger, so 288 * should be used in preference unless the triggering function 289 * actually needs to know the classdev. 290 */ 291 void 292 attribute_container_trigger(struct device *dev, 293 int (*fn)(struct attribute_container *, 294 struct device *)) 295 { 296 struct attribute_container *cont; 297 298 mutex_lock(&attribute_container_mutex); 299 list_for_each_entry(cont, &attribute_container_list, node) { 300 if (cont->match(cont, dev)) 301 fn(cont, dev); 302 } 303 mutex_unlock(&attribute_container_mutex); 304 } 305 306 /** 307 * attribute_container_add_attrs - add attributes 308 * 309 * @classdev: The class device 310 * 311 * This simply creates all the class device sysfs files from the 312 * attributes listed in the container 313 */ 314 int 315 attribute_container_add_attrs(struct device *classdev) 316 { 317 struct attribute_container *cont = 318 attribute_container_classdev_to_container(classdev); 319 struct device_attribute **attrs = cont->attrs; 320 int i, error; 321 322 BUG_ON(attrs && cont->grp); 323 324 if (!attrs && !cont->grp) 325 return 0; 326 327 if (cont->grp) 328 return sysfs_create_group(&classdev->kobj, cont->grp); 329 330 for (i = 0; attrs[i]; i++) { 331 sysfs_attr_init(&attrs[i]->attr); 332 error = device_create_file(classdev, attrs[i]); 333 if (error) 334 return error; 335 } 336 337 return 0; 338 } 339 340 /** 341 * attribute_container_add_class_device - same function as device_add 342 * 343 * @classdev: the class device to add 344 * 345 * This performs essentially the same function as device_add except for 346 * attribute containers, namely add the classdev to the system and then 347 * create the attribute files 348 */ 349 int 350 attribute_container_add_class_device(struct device *classdev) 351 { 352 int error = device_add(classdev); 353 354 if (error) 355 return error; 356 return attribute_container_add_attrs(classdev); 357 } 358 359 /** 360 * attribute_container_add_class_device_adapter - simple adapter for triggers 361 * 362 * This function is identical to attribute_container_add_class_device except 363 * that it is designed to be called from the triggers 364 */ 365 int 366 attribute_container_add_class_device_adapter(struct attribute_container *cont, 367 struct device *dev, 368 struct device *classdev) 369 { 370 return attribute_container_add_class_device(classdev); 371 } 372 373 /** 374 * attribute_container_remove_attrs - remove any attribute files 375 * 376 * @classdev: The class device to remove the files from 377 * 378 */ 379 void 380 attribute_container_remove_attrs(struct device *classdev) 381 { 382 struct attribute_container *cont = 383 attribute_container_classdev_to_container(classdev); 384 struct device_attribute **attrs = cont->attrs; 385 int i; 386 387 if (!attrs && !cont->grp) 388 return; 389 390 if (cont->grp) { 391 sysfs_remove_group(&classdev->kobj, cont->grp); 392 return ; 393 } 394 395 for (i = 0; attrs[i]; i++) 396 device_remove_file(classdev, attrs[i]); 397 } 398 399 /** 400 * attribute_container_class_device_del - equivalent of class_device_del 401 * 402 * @classdev: the class device 403 * 404 * This function simply removes all the attribute files and then calls 405 * device_del. 406 */ 407 void 408 attribute_container_class_device_del(struct device *classdev) 409 { 410 attribute_container_remove_attrs(classdev); 411 device_del(classdev); 412 } 413 414 /** 415 * attribute_container_find_class_device - find the corresponding class_device 416 * 417 * @cont: the container 418 * @dev: the generic device 419 * 420 * Looks up the device in the container's list of class devices and returns 421 * the corresponding class_device. 422 */ 423 struct device * 424 attribute_container_find_class_device(struct attribute_container *cont, 425 struct device *dev) 426 { 427 struct device *cdev = NULL; 428 struct internal_container *ic; 429 struct klist_iter iter; 430 431 klist_for_each_entry(ic, &cont->containers, node, &iter) { 432 if (ic->classdev.parent == dev) { 433 cdev = &ic->classdev; 434 /* FIXME: must exit iterator then break */ 435 klist_iter_exit(&iter); 436 break; 437 } 438 } 439 440 return cdev; 441 } 442 EXPORT_SYMBOL_GPL(attribute_container_find_class_device); 443