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 = 0; 40 41 if (dev_attr->show) 42 ret = dev_attr->show(dev, 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 = 0; 53 54 if (dev_attr->store) 55 ret = dev_attr->store(dev, 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 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 } 193 194 195 /** 196 * device_initialize - init device structure. 197 * @dev: device. 198 * 199 * This prepares the device for use by other layers, 200 * including adding it to the device hierarchy. 201 * It is the first half of device_register(), if called by 202 * that, though it can also be called separately, so one 203 * may use @dev's fields (e.g. the refcount). 204 */ 205 206 void device_initialize(struct device *dev) 207 { 208 kobj_set_kset_s(dev, devices_subsys); 209 kobject_init(&dev->kobj); 210 INIT_LIST_HEAD(&dev->node); 211 INIT_LIST_HEAD(&dev->children); 212 INIT_LIST_HEAD(&dev->driver_list); 213 INIT_LIST_HEAD(&dev->bus_list); 214 INIT_LIST_HEAD(&dev->dma_pools); 215 } 216 217 /** 218 * device_add - add device to device hierarchy. 219 * @dev: device. 220 * 221 * This is part 2 of device_register(), though may be called 222 * separately _iff_ device_initialize() has been called separately. 223 * 224 * This adds it to the kobject hierarchy via kobject_add(), adds it 225 * to the global and sibling lists for the device, then 226 * adds it to the other relevant subsystems of the driver model. 227 */ 228 int device_add(struct device *dev) 229 { 230 struct device *parent = NULL; 231 int error = -EINVAL; 232 233 dev = get_device(dev); 234 if (!dev || !strlen(dev->bus_id)) 235 goto Error; 236 237 parent = get_device(dev->parent); 238 239 pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id); 240 241 /* first, register with generic layer. */ 242 kobject_set_name(&dev->kobj, "%s", dev->bus_id); 243 if (parent) 244 dev->kobj.parent = &parent->kobj; 245 246 if ((error = kobject_add(&dev->kobj))) 247 goto Error; 248 kobject_hotplug(&dev->kobj, KOBJ_ADD); 249 if ((error = device_pm_add(dev))) 250 goto PMError; 251 if ((error = bus_add_device(dev))) 252 goto BusError; 253 down_write(&devices_subsys.rwsem); 254 if (parent) 255 list_add_tail(&dev->node, &parent->children); 256 up_write(&devices_subsys.rwsem); 257 258 /* notify platform of device entry */ 259 if (platform_notify) 260 platform_notify(dev); 261 Done: 262 put_device(dev); 263 return error; 264 BusError: 265 device_pm_remove(dev); 266 PMError: 267 kobject_hotplug(&dev->kobj, KOBJ_REMOVE); 268 kobject_del(&dev->kobj); 269 Error: 270 if (parent) 271 put_device(parent); 272 goto Done; 273 } 274 275 276 /** 277 * device_register - register a device with the system. 278 * @dev: pointer to the device structure 279 * 280 * This happens in two clean steps - initialize the device 281 * and add it to the system. The two steps can be called 282 * separately, but this is the easiest and most common. 283 * I.e. you should only call the two helpers separately if 284 * have a clearly defined need to use and refcount the device 285 * before it is added to the hierarchy. 286 */ 287 288 int device_register(struct device *dev) 289 { 290 device_initialize(dev); 291 return device_add(dev); 292 } 293 294 295 /** 296 * get_device - increment reference count for device. 297 * @dev: device. 298 * 299 * This simply forwards the call to kobject_get(), though 300 * we do take care to provide for the case that we get a NULL 301 * pointer passed in. 302 */ 303 304 struct device * get_device(struct device * dev) 305 { 306 return dev ? to_dev(kobject_get(&dev->kobj)) : NULL; 307 } 308 309 310 /** 311 * put_device - decrement reference count. 312 * @dev: device in question. 313 */ 314 void put_device(struct device * dev) 315 { 316 if (dev) 317 kobject_put(&dev->kobj); 318 } 319 320 321 /** 322 * device_del - delete device from system. 323 * @dev: device. 324 * 325 * This is the first part of the device unregistration 326 * sequence. This removes the device from the lists we control 327 * from here, has it removed from the other driver model 328 * subsystems it was added to in device_add(), and removes it 329 * from the kobject hierarchy. 330 * 331 * NOTE: this should be called manually _iff_ device_add() was 332 * also called manually. 333 */ 334 335 void device_del(struct device * dev) 336 { 337 struct device * parent = dev->parent; 338 339 down_write(&devices_subsys.rwsem); 340 if (parent) 341 list_del_init(&dev->node); 342 up_write(&devices_subsys.rwsem); 343 344 /* Notify the platform of the removal, in case they 345 * need to do anything... 346 */ 347 if (platform_notify_remove) 348 platform_notify_remove(dev); 349 bus_remove_device(dev); 350 device_pm_remove(dev); 351 kobject_hotplug(&dev->kobj, KOBJ_REMOVE); 352 kobject_del(&dev->kobj); 353 if (parent) 354 put_device(parent); 355 } 356 357 /** 358 * device_unregister - unregister device from system. 359 * @dev: device going away. 360 * 361 * We do this in two parts, like we do device_register(). First, 362 * we remove it from all the subsystems with device_del(), then 363 * we decrement the reference count via put_device(). If that 364 * is the final reference count, the device will be cleaned up 365 * via device_release() above. Otherwise, the structure will 366 * stick around until the final reference to the device is dropped. 367 */ 368 void device_unregister(struct device * dev) 369 { 370 pr_debug("DEV: Unregistering device. ID = '%s'\n", dev->bus_id); 371 device_del(dev); 372 put_device(dev); 373 } 374 375 376 /** 377 * device_for_each_child - device child iterator. 378 * @dev: parent struct device. 379 * @data: data for the callback. 380 * @fn: function to be called for each device. 381 * 382 * Iterate over @dev's child devices, and call @fn for each, 383 * passing it @data. 384 * 385 * We check the return of @fn each time. If it returns anything 386 * other than 0, we break out and return that value. 387 */ 388 int device_for_each_child(struct device * dev, void * data, 389 int (*fn)(struct device *, void *)) 390 { 391 struct device * child; 392 int error = 0; 393 394 down_read(&devices_subsys.rwsem); 395 list_for_each_entry(child, &dev->children, node) { 396 if((error = fn(child, data))) 397 break; 398 } 399 up_read(&devices_subsys.rwsem); 400 return error; 401 } 402 403 /** 404 * device_find - locate device on a bus by name. 405 * @name: name of the device. 406 * @bus: bus to scan for the device. 407 * 408 * Call kset_find_obj() to iterate over list of devices on 409 * a bus to find device by name. Return device if found. 410 * 411 * Note that kset_find_obj increments device's reference count. 412 */ 413 struct device *device_find(const char *name, struct bus_type *bus) 414 { 415 struct kobject *k = kset_find_obj(&bus->devices, name); 416 if (k) 417 return to_dev(k); 418 return NULL; 419 } 420 421 int __init devices_init(void) 422 { 423 return subsystem_register(&devices_subsys); 424 } 425 426 EXPORT_SYMBOL_GPL(device_for_each_child); 427 428 EXPORT_SYMBOL_GPL(device_initialize); 429 EXPORT_SYMBOL_GPL(device_add); 430 EXPORT_SYMBOL_GPL(device_register); 431 432 EXPORT_SYMBOL_GPL(device_del); 433 EXPORT_SYMBOL_GPL(device_unregister); 434 EXPORT_SYMBOL_GPL(get_device); 435 EXPORT_SYMBOL_GPL(put_device); 436 EXPORT_SYMBOL_GPL(device_find); 437 438 EXPORT_SYMBOL_GPL(device_create_file); 439 EXPORT_SYMBOL_GPL(device_remove_file); 440