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 } 193 194 195 /** 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 klist_init(&dev->klist_children); 211 INIT_LIST_HEAD(&dev->dma_pools); 212 init_MUTEX(&dev->sem); 213 } 214 215 /** 216 * device_add - add device to device hierarchy. 217 * @dev: device. 218 * 219 * This is part 2 of device_register(), though may be called 220 * separately _iff_ device_initialize() has been called separately. 221 * 222 * This adds it to the kobject hierarchy via kobject_add(), adds it 223 * to the global and sibling lists for the device, then 224 * adds it to the other relevant subsystems of the driver model. 225 */ 226 int device_add(struct device *dev) 227 { 228 struct device *parent = NULL; 229 int error = -EINVAL; 230 231 dev = get_device(dev); 232 if (!dev || !strlen(dev->bus_id)) 233 goto Error; 234 235 parent = get_device(dev->parent); 236 237 pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id); 238 239 /* first, register with generic layer. */ 240 kobject_set_name(&dev->kobj, "%s", dev->bus_id); 241 if (parent) 242 dev->kobj.parent = &parent->kobj; 243 244 if ((error = kobject_add(&dev->kobj))) 245 goto Error; 246 kobject_hotplug(&dev->kobj, KOBJ_ADD); 247 if ((error = device_pm_add(dev))) 248 goto PMError; 249 if ((error = bus_add_device(dev))) 250 goto BusError; 251 if (parent) 252 klist_add_tail(&parent->klist_children, &dev->knode_parent); 253 254 /* notify platform of device entry */ 255 if (platform_notify) 256 platform_notify(dev); 257 Done: 258 put_device(dev); 259 return error; 260 BusError: 261 device_pm_remove(dev); 262 PMError: 263 kobject_hotplug(&dev->kobj, KOBJ_REMOVE); 264 kobject_del(&dev->kobj); 265 Error: 266 if (parent) 267 put_device(parent); 268 goto Done; 269 } 270 271 272 /** 273 * device_register - register a device with the system. 274 * @dev: pointer to the device structure 275 * 276 * This happens in two clean steps - initialize the device 277 * and add it to the system. The two steps can be called 278 * separately, but this is the easiest and most common. 279 * I.e. you should only call the two helpers separately if 280 * have a clearly defined need to use and refcount the device 281 * before it is added to the hierarchy. 282 */ 283 284 int device_register(struct device *dev) 285 { 286 device_initialize(dev); 287 return device_add(dev); 288 } 289 290 291 /** 292 * get_device - increment reference count for device. 293 * @dev: device. 294 * 295 * This simply forwards the call to kobject_get(), though 296 * we do take care to provide for the case that we get a NULL 297 * pointer passed in. 298 */ 299 300 struct device * get_device(struct device * dev) 301 { 302 return dev ? to_dev(kobject_get(&dev->kobj)) : NULL; 303 } 304 305 306 /** 307 * put_device - decrement reference count. 308 * @dev: device in question. 309 */ 310 void put_device(struct device * dev) 311 { 312 if (dev) 313 kobject_put(&dev->kobj); 314 } 315 316 317 /** 318 * device_del - delete device from system. 319 * @dev: device. 320 * 321 * This is the first part of the device unregistration 322 * sequence. This removes the device from the lists we control 323 * from here, has it removed from the other driver model 324 * subsystems it was added to in device_add(), and removes it 325 * from the kobject hierarchy. 326 * 327 * NOTE: this should be called manually _iff_ device_add() was 328 * also called manually. 329 */ 330 331 void device_del(struct device * dev) 332 { 333 struct device * parent = dev->parent; 334 335 if (parent) 336 klist_del(&dev->knode_parent); 337 338 /* Notify the platform of the removal, in case they 339 * need to do anything... 340 */ 341 if (platform_notify_remove) 342 platform_notify_remove(dev); 343 bus_remove_device(dev); 344 device_pm_remove(dev); 345 kobject_hotplug(&dev->kobj, KOBJ_REMOVE); 346 kobject_del(&dev->kobj); 347 if (parent) 348 put_device(parent); 349 } 350 351 /** 352 * device_unregister - unregister device from system. 353 * @dev: device going away. 354 * 355 * We do this in two parts, like we do device_register(). First, 356 * we remove it from all the subsystems with device_del(), then 357 * we decrement the reference count via put_device(). If that 358 * is the final reference count, the device will be cleaned up 359 * via device_release() above. Otherwise, the structure will 360 * stick around until the final reference to the device is dropped. 361 */ 362 void device_unregister(struct device * dev) 363 { 364 pr_debug("DEV: Unregistering device. ID = '%s'\n", dev->bus_id); 365 device_del(dev); 366 put_device(dev); 367 } 368 369 370 static struct device * next_device(struct klist_iter * i) 371 { 372 struct klist_node * n = klist_next(i); 373 return n ? container_of(n, struct device, knode_parent) : NULL; 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 * parent, void * data, 389 int (*fn)(struct device *, void *)) 390 { 391 struct klist_iter i; 392 struct device * child; 393 int error = 0; 394 395 klist_iter_init(&parent->klist_children, &i); 396 while ((child = next_device(&i)) && !error) 397 error = fn(child, data); 398 klist_iter_exit(&i); 399 return error; 400 } 401 402 int __init devices_init(void) 403 { 404 return subsystem_register(&devices_subsys); 405 } 406 407 EXPORT_SYMBOL_GPL(device_for_each_child); 408 409 EXPORT_SYMBOL_GPL(device_initialize); 410 EXPORT_SYMBOL_GPL(device_add); 411 EXPORT_SYMBOL_GPL(device_register); 412 413 EXPORT_SYMBOL_GPL(device_del); 414 EXPORT_SYMBOL_GPL(device_unregister); 415 EXPORT_SYMBOL_GPL(get_device); 416 EXPORT_SYMBOL_GPL(put_device); 417 418 EXPORT_SYMBOL_GPL(device_create_file); 419 EXPORT_SYMBOL_GPL(device_remove_file); 420