1 /* 2 * drivers/base/core.c - core driver model code (device registration, etc) 3 * 4 * Copyright (c) 2002-3 Patrick Mochel 5 * Copyright (c) 2002-3 Open Source Development Labs 6 * 7 * This file is released under the GPLv2 8 * 9 */ 10 11 #include <linux/config.h> 12 #include <linux/device.h> 13 #include <linux/err.h> 14 #include <linux/init.h> 15 #include <linux/module.h> 16 #include <linux/slab.h> 17 #include <linux/string.h> 18 19 #include <asm/semaphore.h> 20 21 #include "base.h" 22 #include "power/power.h" 23 24 int (*platform_notify)(struct device * dev) = NULL; 25 int (*platform_notify_remove)(struct device * dev) = NULL; 26 27 /* 28 * sysfs bindings for devices. 29 */ 30 31 #define to_dev(obj) container_of(obj, struct device, kobj) 32 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr) 33 34 static ssize_t 35 dev_attr_show(struct kobject * kobj, struct attribute * attr, char * buf) 36 { 37 struct device_attribute * dev_attr = to_dev_attr(attr); 38 struct device * dev = to_dev(kobj); 39 ssize_t ret = -EIO; 40 41 if (dev_attr->show) 42 ret = dev_attr->show(dev, dev_attr, buf); 43 return ret; 44 } 45 46 static ssize_t 47 dev_attr_store(struct kobject * kobj, struct attribute * attr, 48 const char * buf, size_t count) 49 { 50 struct device_attribute * dev_attr = to_dev_attr(attr); 51 struct device * dev = to_dev(kobj); 52 ssize_t ret = -EIO; 53 54 if (dev_attr->store) 55 ret = dev_attr->store(dev, dev_attr, buf, count); 56 return ret; 57 } 58 59 static struct sysfs_ops dev_sysfs_ops = { 60 .show = dev_attr_show, 61 .store = dev_attr_store, 62 }; 63 64 65 /** 66 * device_release - free device structure. 67 * @kobj: device's kobject. 68 * 69 * This is called once the reference count for the object 70 * reaches 0. We forward the call to the device's release 71 * method, which should handle actually freeing the structure. 72 */ 73 static void device_release(struct kobject * kobj) 74 { 75 struct device * dev = to_dev(kobj); 76 77 if (dev->release) 78 dev->release(dev); 79 else { 80 printk(KERN_ERR "Device '%s' does not have a release() function, " 81 "it is broken and must be fixed.\n", 82 dev->bus_id); 83 WARN_ON(1); 84 } 85 } 86 87 static struct kobj_type ktype_device = { 88 .release = device_release, 89 .sysfs_ops = &dev_sysfs_ops, 90 }; 91 92 93 static int dev_hotplug_filter(struct kset *kset, struct kobject *kobj) 94 { 95 struct kobj_type *ktype = get_ktype(kobj); 96 97 if (ktype == &ktype_device) { 98 struct device *dev = to_dev(kobj); 99 if (dev->bus) 100 return 1; 101 } 102 return 0; 103 } 104 105 static const char *dev_hotplug_name(struct kset *kset, struct kobject *kobj) 106 { 107 struct device *dev = to_dev(kobj); 108 109 return dev->bus->name; 110 } 111 112 static int dev_hotplug(struct kset *kset, struct kobject *kobj, char **envp, 113 int num_envp, char *buffer, int buffer_size) 114 { 115 struct device *dev = to_dev(kobj); 116 int i = 0; 117 int length = 0; 118 int retval = 0; 119 120 /* add bus name of physical device */ 121 if (dev->bus) 122 add_hotplug_env_var(envp, num_envp, &i, 123 buffer, buffer_size, &length, 124 "PHYSDEVBUS=%s", dev->bus->name); 125 126 /* add driver name of physical device */ 127 if (dev->driver) 128 add_hotplug_env_var(envp, num_envp, &i, 129 buffer, buffer_size, &length, 130 "PHYSDEVDRIVER=%s", dev->driver->name); 131 132 /* terminate, set to next free slot, shrink available space */ 133 envp[i] = NULL; 134 envp = &envp[i]; 135 num_envp -= i; 136 buffer = &buffer[length]; 137 buffer_size -= length; 138 139 if (dev->bus && dev->bus->hotplug) { 140 /* have the bus specific function add its stuff */ 141 retval = dev->bus->hotplug (dev, envp, num_envp, buffer, buffer_size); 142 if (retval) { 143 pr_debug ("%s - hotplug() returned %d\n", 144 __FUNCTION__, retval); 145 } 146 } 147 148 return retval; 149 } 150 151 static struct kset_hotplug_ops device_hotplug_ops = { 152 .filter = dev_hotplug_filter, 153 .name = dev_hotplug_name, 154 .hotplug = dev_hotplug, 155 }; 156 157 /** 158 * device_subsys - structure to be registered with kobject core. 159 */ 160 161 decl_subsys(devices, &ktype_device, &device_hotplug_ops); 162 163 164 /** 165 * device_create_file - create sysfs attribute file for device. 166 * @dev: device. 167 * @attr: device attribute descriptor. 168 */ 169 170 int device_create_file(struct device * dev, struct device_attribute * attr) 171 { 172 int error = 0; 173 if (get_device(dev)) { 174 error = sysfs_create_file(&dev->kobj, &attr->attr); 175 put_device(dev); 176 } 177 return error; 178 } 179 180 /** 181 * device_remove_file - remove sysfs attribute file. 182 * @dev: device. 183 * @attr: device attribute descriptor. 184 */ 185 186 void device_remove_file(struct device * dev, struct device_attribute * attr) 187 { 188 if (get_device(dev)) { 189 sysfs_remove_file(&dev->kobj, &attr->attr); 190 put_device(dev); 191 } 192 } 193 194 static void klist_children_get(struct klist_node *n) 195 { 196 struct device *dev = container_of(n, struct device, knode_parent); 197 198 get_device(dev); 199 } 200 201 static void klist_children_put(struct klist_node *n) 202 { 203 struct device *dev = container_of(n, struct device, knode_parent); 204 205 put_device(dev); 206 } 207 208 209 /** 210 * device_initialize - init device structure. 211 * @dev: device. 212 * 213 * This prepares the device for use by other layers, 214 * including adding it to the device hierarchy. 215 * It is the first half of device_register(), if called by 216 * that, though it can also be called separately, so one 217 * may use @dev's fields (e.g. the refcount). 218 */ 219 220 void device_initialize(struct device *dev) 221 { 222 kobj_set_kset_s(dev, devices_subsys); 223 kobject_init(&dev->kobj); 224 klist_init(&dev->klist_children, klist_children_get, 225 klist_children_put); 226 INIT_LIST_HEAD(&dev->dma_pools); 227 init_MUTEX(&dev->sem); 228 } 229 230 /** 231 * device_add - add device to device hierarchy. 232 * @dev: device. 233 * 234 * This is part 2 of device_register(), though may be called 235 * separately _iff_ device_initialize() has been called separately. 236 * 237 * This adds it to the kobject hierarchy via kobject_add(), adds it 238 * to the global and sibling lists for the device, then 239 * adds it to the other relevant subsystems of the driver model. 240 */ 241 int device_add(struct device *dev) 242 { 243 struct device *parent = NULL; 244 int error = -EINVAL; 245 246 dev = get_device(dev); 247 if (!dev || !strlen(dev->bus_id)) 248 goto Error; 249 250 parent = get_device(dev->parent); 251 252 pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id); 253 254 /* first, register with generic layer. */ 255 kobject_set_name(&dev->kobj, "%s", dev->bus_id); 256 if (parent) 257 dev->kobj.parent = &parent->kobj; 258 259 if ((error = kobject_add(&dev->kobj))) 260 goto Error; 261 kobject_hotplug(&dev->kobj, KOBJ_ADD); 262 if ((error = device_pm_add(dev))) 263 goto PMError; 264 if ((error = bus_add_device(dev))) 265 goto BusError; 266 if (parent) 267 klist_add_tail(&dev->knode_parent, &parent->klist_children); 268 269 /* notify platform of device entry */ 270 if (platform_notify) 271 platform_notify(dev); 272 Done: 273 put_device(dev); 274 return error; 275 BusError: 276 device_pm_remove(dev); 277 PMError: 278 kobject_hotplug(&dev->kobj, KOBJ_REMOVE); 279 kobject_del(&dev->kobj); 280 Error: 281 if (parent) 282 put_device(parent); 283 goto Done; 284 } 285 286 287 /** 288 * device_register - register a device with the system. 289 * @dev: pointer to the device structure 290 * 291 * This happens in two clean steps - initialize the device 292 * and add it to the system. The two steps can be called 293 * separately, but this is the easiest and most common. 294 * I.e. you should only call the two helpers separately if 295 * have a clearly defined need to use and refcount the device 296 * before it is added to the hierarchy. 297 */ 298 299 int device_register(struct device *dev) 300 { 301 device_initialize(dev); 302 return device_add(dev); 303 } 304 305 306 /** 307 * get_device - increment reference count for device. 308 * @dev: device. 309 * 310 * This simply forwards the call to kobject_get(), though 311 * we do take care to provide for the case that we get a NULL 312 * pointer passed in. 313 */ 314 315 struct device * get_device(struct device * dev) 316 { 317 return dev ? to_dev(kobject_get(&dev->kobj)) : NULL; 318 } 319 320 321 /** 322 * put_device - decrement reference count. 323 * @dev: device in question. 324 */ 325 void put_device(struct device * dev) 326 { 327 if (dev) 328 kobject_put(&dev->kobj); 329 } 330 331 332 /** 333 * device_del - delete device from system. 334 * @dev: device. 335 * 336 * This is the first part of the device unregistration 337 * sequence. This removes the device from the lists we control 338 * from here, has it removed from the other driver model 339 * subsystems it was added to in device_add(), and removes it 340 * from the kobject hierarchy. 341 * 342 * NOTE: this should be called manually _iff_ device_add() was 343 * also called manually. 344 */ 345 346 void device_del(struct device * dev) 347 { 348 struct device * parent = dev->parent; 349 350 if (parent) 351 klist_del(&dev->knode_parent); 352 353 /* Notify the platform of the removal, in case they 354 * need to do anything... 355 */ 356 if (platform_notify_remove) 357 platform_notify_remove(dev); 358 bus_remove_device(dev); 359 device_pm_remove(dev); 360 kobject_hotplug(&dev->kobj, KOBJ_REMOVE); 361 kobject_del(&dev->kobj); 362 if (parent) 363 put_device(parent); 364 } 365 366 /** 367 * device_unregister - unregister device from system. 368 * @dev: device going away. 369 * 370 * We do this in two parts, like we do device_register(). First, 371 * we remove it from all the subsystems with device_del(), then 372 * we decrement the reference count via put_device(). If that 373 * is the final reference count, the device will be cleaned up 374 * via device_release() above. Otherwise, the structure will 375 * stick around until the final reference to the device is dropped. 376 */ 377 void device_unregister(struct device * dev) 378 { 379 pr_debug("DEV: Unregistering device. ID = '%s'\n", dev->bus_id); 380 device_del(dev); 381 put_device(dev); 382 } 383 384 385 static struct device * next_device(struct klist_iter * i) 386 { 387 struct klist_node * n = klist_next(i); 388 return n ? container_of(n, struct device, knode_parent) : NULL; 389 } 390 391 /** 392 * device_for_each_child - device child iterator. 393 * @dev: parent struct device. 394 * @data: data for the callback. 395 * @fn: function to be called for each device. 396 * 397 * Iterate over @dev's child devices, and call @fn for each, 398 * passing it @data. 399 * 400 * We check the return of @fn each time. If it returns anything 401 * other than 0, we break out and return that value. 402 */ 403 int device_for_each_child(struct device * parent, void * data, 404 int (*fn)(struct device *, void *)) 405 { 406 struct klist_iter i; 407 struct device * child; 408 int error = 0; 409 410 klist_iter_init(&parent->klist_children, &i); 411 while ((child = next_device(&i)) && !error) 412 error = fn(child, data); 413 klist_iter_exit(&i); 414 return error; 415 } 416 417 int __init devices_init(void) 418 { 419 return subsystem_register(&devices_subsys); 420 } 421 422 EXPORT_SYMBOL_GPL(device_for_each_child); 423 424 EXPORT_SYMBOL_GPL(device_initialize); 425 EXPORT_SYMBOL_GPL(device_add); 426 EXPORT_SYMBOL_GPL(device_register); 427 428 EXPORT_SYMBOL_GPL(device_del); 429 EXPORT_SYMBOL_GPL(device_unregister); 430 EXPORT_SYMBOL_GPL(get_device); 431 EXPORT_SYMBOL_GPL(put_device); 432 433 EXPORT_SYMBOL_GPL(device_create_file); 434 EXPORT_SYMBOL_GPL(device_remove_file); 435