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/init.h> 16 #include <linux/device.h> 17 #include <linux/kernel.h> 18 #include <linux/slab.h> 19 #include <linux/list.h> 20 #include <linux/module.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 class_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 class_device_get(&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 class_device_put(&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 class_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 struct list_head attribute_container_list; 64 65 static DECLARE_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 down(&attribute_container_mutex); 81 list_add_tail(&cont->node, &attribute_container_list); 82 up(&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 down(&attribute_container_mutex); 98 spin_lock(&cont->containers.k_lock); 99 if (!list_empty(&cont->containers.k_list)) 100 goto out; 101 retval = 0; 102 list_del(&cont->node); 103 out: 104 spin_unlock(&cont->containers.k_lock); 105 up(&attribute_container_mutex); 106 return retval; 107 108 } 109 EXPORT_SYMBOL_GPL(attribute_container_unregister); 110 111 /* private function used as class release */ 112 static void attribute_container_release(struct class_device *classdev) 113 { 114 struct internal_container *ic 115 = container_of(classdev, struct internal_container, classdev); 116 struct device *dev = classdev->dev; 117 118 kfree(ic); 119 put_device(dev); 120 } 121 122 /** 123 * attribute_container_add_device - see if any container is interested in dev 124 * 125 * @dev: device to add attributes to 126 * @fn: function to trigger addition of class device. 127 * 128 * This function allocates storage for the class device(s) to be 129 * attached to dev (one for each matching attribute_container). If no 130 * fn is provided, the code will simply register the class device via 131 * class_device_add. If a function is provided, it is expected to add 132 * the class device at the appropriate time. One of the things that 133 * might be necessary is to allocate and initialise the classdev and 134 * then add it a later time. To do this, call this routine for 135 * allocation and initialisation and then use 136 * attribute_container_device_trigger() to call class_device_add() on 137 * it. Note: after this, the class device contains a reference to dev 138 * which is not relinquished until the release of the classdev. 139 */ 140 void 141 attribute_container_add_device(struct device *dev, 142 int (*fn)(struct attribute_container *, 143 struct device *, 144 struct class_device *)) 145 { 146 struct attribute_container *cont; 147 148 down(&attribute_container_mutex); 149 list_for_each_entry(cont, &attribute_container_list, node) { 150 struct internal_container *ic; 151 152 if (attribute_container_no_classdevs(cont)) 153 continue; 154 155 if (!cont->match(cont, dev)) 156 continue; 157 158 ic = kzalloc(sizeof(*ic), GFP_KERNEL); 159 if (!ic) { 160 dev_printk(KERN_ERR, dev, "failed to allocate class container\n"); 161 continue; 162 } 163 164 ic->cont = cont; 165 class_device_initialize(&ic->classdev); 166 ic->classdev.dev = get_device(dev); 167 ic->classdev.class = cont->class; 168 cont->class->release = attribute_container_release; 169 strcpy(ic->classdev.class_id, dev->bus_id); 170 if (fn) 171 fn(cont, dev, &ic->classdev); 172 else 173 attribute_container_add_class_device(&ic->classdev); 174 klist_add_tail(&ic->node, &cont->containers); 175 } 176 up(&attribute_container_mutex); 177 } 178 179 /* FIXME: can't break out of this unless klist_iter_exit is also 180 * called before doing the break 181 */ 182 #define klist_for_each_entry(pos, head, member, iter) \ 183 for (klist_iter_init(head, iter); (pos = ({ \ 184 struct klist_node *n = klist_next(iter); \ 185 n ? container_of(n, typeof(*pos), member) : \ 186 ({ klist_iter_exit(iter) ; NULL; }); \ 187 }) ) != NULL; ) 188 189 190 /** 191 * attribute_container_remove_device - make device eligible for removal. 192 * 193 * @dev: The generic device 194 * @fn: A function to call to remove the device 195 * 196 * This routine triggers device removal. If fn is NULL, then it is 197 * simply done via class_device_unregister (note that if something 198 * still has a reference to the classdev, then the memory occupied 199 * will not be freed until the classdev is released). If you want a 200 * two phase release: remove from visibility and then delete the 201 * device, then you should use this routine with a fn that calls 202 * class_device_del() and then use 203 * attribute_container_device_trigger() to do the final put on the 204 * classdev. 205 */ 206 void 207 attribute_container_remove_device(struct device *dev, 208 void (*fn)(struct attribute_container *, 209 struct device *, 210 struct class_device *)) 211 { 212 struct attribute_container *cont; 213 214 down(&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.dev) 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 class_device_unregister(&ic->classdev); 234 } 235 } 236 } 237 up(&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 funcion 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 class_device *)) 255 { 256 struct attribute_container *cont; 257 258 down(&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.dev) 273 fn(cont, dev, &ic->classdev); 274 } 275 } 276 up(&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 down(&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 up(&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 class_device *classdev) 316 { 317 struct attribute_container *cont = 318 attribute_container_classdev_to_container(classdev); 319 struct class_device_attribute **attrs = cont->attrs; 320 int i, error; 321 322 if (!attrs) 323 return 0; 324 325 for (i = 0; attrs[i]; i++) { 326 error = class_device_create_file(classdev, attrs[i]); 327 if (error) 328 return error; 329 } 330 331 return 0; 332 } 333 334 /** 335 * attribute_container_add_class_device - same function as class_device_add 336 * 337 * @classdev: the class device to add 338 * 339 * This performs essentially the same function as class_device_add except for 340 * attribute containers, namely add the classdev to the system and then 341 * create the attribute files 342 */ 343 int 344 attribute_container_add_class_device(struct class_device *classdev) 345 { 346 int error = class_device_add(classdev); 347 if (error) 348 return error; 349 return attribute_container_add_attrs(classdev); 350 } 351 352 /** 353 * attribute_container_add_class_device_adapter - simple adapter for triggers 354 * 355 * This function is identical to attribute_container_add_class_device except 356 * that it is designed to be called from the triggers 357 */ 358 int 359 attribute_container_add_class_device_adapter(struct attribute_container *cont, 360 struct device *dev, 361 struct class_device *classdev) 362 { 363 return attribute_container_add_class_device(classdev); 364 } 365 366 /** 367 * attribute_container_remove_attrs - remove any attribute files 368 * 369 * @classdev: The class device to remove the files from 370 * 371 */ 372 void 373 attribute_container_remove_attrs(struct class_device *classdev) 374 { 375 struct attribute_container *cont = 376 attribute_container_classdev_to_container(classdev); 377 struct class_device_attribute **attrs = cont->attrs; 378 int i; 379 380 if (!attrs) 381 return; 382 383 for (i = 0; attrs[i]; i++) 384 class_device_remove_file(classdev, attrs[i]); 385 } 386 387 /** 388 * attribute_container_class_device_del - equivalent of class_device_del 389 * 390 * @classdev: the class device 391 * 392 * This function simply removes all the attribute files and then calls 393 * class_device_del. 394 */ 395 void 396 attribute_container_class_device_del(struct class_device *classdev) 397 { 398 attribute_container_remove_attrs(classdev); 399 class_device_del(classdev); 400 } 401 402 /** 403 * attribute_container_find_class_device - find the corresponding class_device 404 * 405 * @cont: the container 406 * @dev: the generic device 407 * 408 * Looks up the device in the container's list of class devices and returns 409 * the corresponding class_device. 410 */ 411 struct class_device * 412 attribute_container_find_class_device(struct attribute_container *cont, 413 struct device *dev) 414 { 415 struct class_device *cdev = NULL; 416 struct internal_container *ic; 417 struct klist_iter iter; 418 419 klist_for_each_entry(ic, &cont->containers, node, &iter) { 420 if (ic->classdev.dev == dev) { 421 cdev = &ic->classdev; 422 /* FIXME: must exit iterator then break */ 423 klist_iter_exit(&iter); 424 break; 425 } 426 } 427 428 return cdev; 429 } 430 EXPORT_SYMBOL_GPL(attribute_container_find_class_device); 431 432 int __init 433 attribute_container_init(void) 434 { 435 INIT_LIST_HEAD(&attribute_container_list); 436 return 0; 437 } 438