drivers/base/core.c

   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);