linux/include/linux/device.h
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   1/*
   2 * device.h - generic, centralized driver model
   3 *
   4 * Copyright (c) 2001-2003 Patrick Mochel <mochel@osdl.org>
   5 * Copyright (c) 2004-2009 Greg Kroah-Hartman <gregkh@suse.de>
   6 * Copyright (c) 2008-2009 Novell Inc.
   7 *
   8 * This file is released under the GPLv2
   9 *
  10 * See Documentation/driver-model/ for more information.
  11 */
  12
  13#ifndef _DEVICE_H_
  14#define _DEVICE_H_
  15
  16#include <linux/ioport.h>
  17#include <linux/kobject.h>
  18#include <linux/klist.h>
  19#include <linux/list.h>
  20#include <linux/lockdep.h>
  21#include <linux/compiler.h>
  22#include <linux/types.h>
  23#include <linux/mutex.h>
  24#include <linux/pm.h>
  25#include <linux/atomic.h>
  26#include <linux/ratelimit.h>
  27#include <asm/device.h>
  28
  29struct device;
  30struct device_private;
  31struct device_driver;
  32struct driver_private;
  33struct module;
  34struct class;
  35struct subsys_private;
  36struct bus_type;
  37struct device_node;
  38struct iommu_ops;
  39struct iommu_group;
  40
  41struct bus_attribute {
  42        struct attribute        attr;
  43        ssize_t (*show)(struct bus_type *bus, char *buf);
  44        ssize_t (*store)(struct bus_type *bus, const char *buf, size_t count);
  45};
  46
  47#define BUS_ATTR(_name, _mode, _show, _store)   \
  48struct bus_attribute bus_attr_##_name = __ATTR(_name, _mode, _show, _store)
  49
  50extern int __must_check bus_create_file(struct bus_type *,
  51                                        struct bus_attribute *);
  52extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
  53
  54/**
  55 * struct bus_type - The bus type of the device
  56 *
  57 * @name:       The name of the bus.
  58 * @dev_name:   Used for subsystems to enumerate devices like ("foo%u", dev->id).
  59 * @dev_root:   Default device to use as the parent.
  60 * @bus_attrs:  Default attributes of the bus.
  61 * @dev_attrs:  Default attributes of the devices on the bus.
  62 * @drv_attrs:  Default attributes of the device drivers on the bus.
  63 * @match:      Called, perhaps multiple times, whenever a new device or driver
  64 *              is added for this bus. It should return a nonzero value if the
  65 *              given device can be handled by the given driver.
  66 * @uevent:     Called when a device is added, removed, or a few other things
  67 *              that generate uevents to add the environment variables.
  68 * @probe:      Called when a new device or driver add to this bus, and callback
  69 *              the specific driver's probe to initial the matched device.
  70 * @remove:     Called when a device removed from this bus.
  71 * @shutdown:   Called at shut-down time to quiesce the device.
  72 * @suspend:    Called when a device on this bus wants to go to sleep mode.
  73 * @resume:     Called to bring a device on this bus out of sleep mode.
  74 * @pm:         Power management operations of this bus, callback the specific
  75 *              device driver's pm-ops.
  76 * @iommu_ops:  IOMMU specific operations for this bus, used to attach IOMMU
  77 *              driver implementations to a bus and allow the driver to do
  78 *              bus-specific setup
  79 * @p:          The private data of the driver core, only the driver core can
  80 *              touch this.
  81 *
  82 * A bus is a channel between the processor and one or more devices. For the
  83 * purposes of the device model, all devices are connected via a bus, even if
  84 * it is an internal, virtual, "platform" bus. Buses can plug into each other.
  85 * A USB controller is usually a PCI device, for example. The device model
  86 * represents the actual connections between buses and the devices they control.
  87 * A bus is represented by the bus_type structure. It contains the name, the
  88 * default attributes, the bus' methods, PM operations, and the driver core's
  89 * private data.
  90 */
  91struct bus_type {
  92        const char              *name;
  93        const char              *dev_name;
  94        struct device           *dev_root;
  95        struct bus_attribute    *bus_attrs;
  96        struct device_attribute *dev_attrs;
  97        struct driver_attribute *drv_attrs;
  98
  99        int (*match)(struct device *dev, struct device_driver *drv);
 100        int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
 101        int (*probe)(struct device *dev);
 102        int (*remove)(struct device *dev);
 103        void (*shutdown)(struct device *dev);
 104
 105        int (*suspend)(struct device *dev, pm_message_t state);
 106        int (*resume)(struct device *dev);
 107
 108        const struct dev_pm_ops *pm;
 109
 110        struct iommu_ops *iommu_ops;
 111
 112        struct subsys_private *p;
 113};
 114
 115/* This is a #define to keep the compiler from merging different
 116 * instances of the __key variable */
 117#define bus_register(subsys)                    \
 118({                                              \
 119        static struct lock_class_key __key;     \
 120        __bus_register(subsys, &__key); \
 121})
 122extern int __must_check __bus_register(struct bus_type *bus,
 123                                       struct lock_class_key *key);
 124extern void bus_unregister(struct bus_type *bus);
 125
 126extern int __must_check bus_rescan_devices(struct bus_type *bus);
 127
 128/* iterator helpers for buses */
 129struct subsys_dev_iter {
 130        struct klist_iter               ki;
 131        const struct device_type        *type;
 132};
 133void subsys_dev_iter_init(struct subsys_dev_iter *iter,
 134                         struct bus_type *subsys,
 135                         struct device *start,
 136                         const struct device_type *type);
 137struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter);
 138void subsys_dev_iter_exit(struct subsys_dev_iter *iter);
 139
 140int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data,
 141                     int (*fn)(struct device *dev, void *data));
 142struct device *bus_find_device(struct bus_type *bus, struct device *start,
 143                               void *data,
 144                               int (*match)(struct device *dev, void *data));
 145struct device *bus_find_device_by_name(struct bus_type *bus,
 146                                       struct device *start,
 147                                       const char *name);
 148struct device *subsys_find_device_by_id(struct bus_type *bus, unsigned int id,
 149                                        struct device *hint);
 150int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
 151                     void *data, int (*fn)(struct device_driver *, void *));
 152void bus_sort_breadthfirst(struct bus_type *bus,
 153                           int (*compare)(const struct device *a,
 154                                          const struct device *b));
 155/*
 156 * Bus notifiers: Get notified of addition/removal of devices
 157 * and binding/unbinding of drivers to devices.
 158 * In the long run, it should be a replacement for the platform
 159 * notify hooks.
 160 */
 161struct notifier_block;
 162
 163extern int bus_register_notifier(struct bus_type *bus,
 164                                 struct notifier_block *nb);
 165extern int bus_unregister_notifier(struct bus_type *bus,
 166                                   struct notifier_block *nb);
 167
 168/* All 4 notifers below get called with the target struct device *
 169 * as an argument. Note that those functions are likely to be called
 170 * with the device lock held in the core, so be careful.
 171 */
 172#define BUS_NOTIFY_ADD_DEVICE           0x00000001 /* device added */
 173#define BUS_NOTIFY_DEL_DEVICE           0x00000002 /* device removed */
 174#define BUS_NOTIFY_BIND_DRIVER          0x00000003 /* driver about to be
 175                                                      bound */
 176#define BUS_NOTIFY_BOUND_DRIVER         0x00000004 /* driver bound to device */
 177#define BUS_NOTIFY_UNBIND_DRIVER        0x00000005 /* driver about to be
 178                                                      unbound */
 179#define BUS_NOTIFY_UNBOUND_DRIVER       0x00000006 /* driver is unbound
 180                                                      from the device */
 181
 182extern struct kset *bus_get_kset(struct bus_type *bus);
 183extern struct klist *bus_get_device_klist(struct bus_type *bus);
 184
 185/**
 186 * struct device_driver - The basic device driver structure
 187 * @name:       Name of the device driver.
 188 * @bus:        The bus which the device of this driver belongs to.
 189 * @owner:      The module owner.
 190 * @mod_name:   Used for built-in modules.
 191 * @suppress_bind_attrs: Disables bind/unbind via sysfs.
 192 * @of_match_table: The open firmware table.
 193 * @probe:      Called to query the existence of a specific device,
 194 *              whether this driver can work with it, and bind the driver
 195 *              to a specific device.
 196 * @remove:     Called when the device is removed from the system to
 197 *              unbind a device from this driver.
 198 * @shutdown:   Called at shut-down time to quiesce the device.
 199 * @suspend:    Called to put the device to sleep mode. Usually to a
 200 *              low power state.
 201 * @resume:     Called to bring a device from sleep mode.
 202 * @groups:     Default attributes that get created by the driver core
 203 *              automatically.
 204 * @pm:         Power management operations of the device which matched
 205 *              this driver.
 206 * @p:          Driver core's private data, no one other than the driver
 207 *              core can touch this.
 208 *
 209 * The device driver-model tracks all of the drivers known to the system.
 210 * The main reason for this tracking is to enable the driver core to match
 211 * up drivers with new devices. Once drivers are known objects within the
 212 * system, however, a number of other things become possible. Device drivers
 213 * can export information and configuration variables that are independent
 214 * of any specific device.
 215 */
 216struct device_driver {
 217        const char              *name;
 218        struct bus_type         *bus;
 219
 220        struct module           *owner;
 221        const char              *mod_name;      /* used for built-in modules */
 222
 223        bool suppress_bind_attrs;       /* disables bind/unbind via sysfs */
 224
 225        const struct of_device_id       *of_match_table;
 226
 227        int (*probe) (struct device *dev);
 228        int (*remove) (struct device *dev);
 229        void (*shutdown) (struct device *dev);
 230        int (*suspend) (struct device *dev, pm_message_t state);
 231        int (*resume) (struct device *dev);
 232        const struct attribute_group **groups;
 233
 234        const struct dev_pm_ops *pm;
 235
 236        struct driver_private *p;
 237};
 238
 239
 240extern int __must_check driver_register(struct device_driver *drv);
 241extern void driver_unregister(struct device_driver *drv);
 242
 243extern struct device_driver *driver_find(const char *name,
 244                                         struct bus_type *bus);
 245extern int driver_probe_done(void);
 246extern void wait_for_device_probe(void);
 247
 248
 249/* sysfs interface for exporting driver attributes */
 250
 251struct driver_attribute {
 252        struct attribute attr;
 253        ssize_t (*show)(struct device_driver *driver, char *buf);
 254        ssize_t (*store)(struct device_driver *driver, const char *buf,
 255                         size_t count);
 256};
 257
 258#define DRIVER_ATTR(_name, _mode, _show, _store)        \
 259struct driver_attribute driver_attr_##_name =           \
 260        __ATTR(_name, _mode, _show, _store)
 261
 262extern int __must_check driver_create_file(struct device_driver *driver,
 263                                        const struct driver_attribute *attr);
 264extern void driver_remove_file(struct device_driver *driver,
 265                               const struct driver_attribute *attr);
 266
 267extern int __must_check driver_for_each_device(struct device_driver *drv,
 268                                               struct device *start,
 269                                               void *data,
 270                                               int (*fn)(struct device *dev,
 271                                                         void *));
 272struct device *driver_find_device(struct device_driver *drv,
 273                                  struct device *start, void *data,
 274                                  int (*match)(struct device *dev, void *data));
 275
 276/**
 277 * struct subsys_interface - interfaces to device functions
 278 * @name:       name of the device function
 279 * @subsys:     subsytem of the devices to attach to
 280 * @node:       the list of functions registered at the subsystem
 281 * @add_dev:    device hookup to device function handler
 282 * @remove_dev: device hookup to device function handler
 283 *
 284 * Simple interfaces attached to a subsystem. Multiple interfaces can
 285 * attach to a subsystem and its devices. Unlike drivers, they do not
 286 * exclusively claim or control devices. Interfaces usually represent
 287 * a specific functionality of a subsystem/class of devices.
 288 */
 289struct subsys_interface {
 290        const char *name;
 291        struct bus_type *subsys;
 292        struct list_head node;
 293        int (*add_dev)(struct device *dev, struct subsys_interface *sif);
 294        int (*remove_dev)(struct device *dev, struct subsys_interface *sif);
 295};
 296
 297int subsys_interface_register(struct subsys_interface *sif);
 298void subsys_interface_unregister(struct subsys_interface *sif);
 299
 300int subsys_system_register(struct bus_type *subsys,
 301                           const struct attribute_group **groups);
 302
 303/**
 304 * struct class - device classes
 305 * @name:       Name of the class.
 306 * @owner:      The module owner.
 307 * @class_attrs: Default attributes of this class.
 308 * @dev_attrs:  Default attributes of the devices belong to the class.
 309 * @dev_bin_attrs: Default binary attributes of the devices belong to the class.
 310 * @dev_kobj:   The kobject that represents this class and links it into the hierarchy.
 311 * @dev_uevent: Called when a device is added, removed from this class, or a
 312 *              few other things that generate uevents to add the environment
 313 *              variables.
 314 * @devnode:    Callback to provide the devtmpfs.
 315 * @class_release: Called to release this class.
 316 * @dev_release: Called to release the device.
 317 * @suspend:    Used to put the device to sleep mode, usually to a low power
 318 *              state.
 319 * @resume:     Used to bring the device from the sleep mode.
 320 * @ns_type:    Callbacks so sysfs can detemine namespaces.
 321 * @namespace:  Namespace of the device belongs to this class.
 322 * @pm:         The default device power management operations of this class.
 323 * @p:          The private data of the driver core, no one other than the
 324 *              driver core can touch this.
 325 *
 326 * A class is a higher-level view of a device that abstracts out low-level
 327 * implementation details. Drivers may see a SCSI disk or an ATA disk, but,
 328 * at the class level, they are all simply disks. Classes allow user space
 329 * to work with devices based on what they do, rather than how they are
 330 * connected or how they work.
 331 */
 332struct class {
 333        const char              *name;
 334        struct module           *owner;
 335
 336        struct class_attribute          *class_attrs;
 337        struct device_attribute         *dev_attrs;
 338        struct bin_attribute            *dev_bin_attrs;
 339        struct kobject                  *dev_kobj;
 340
 341        int (*dev_uevent)(struct device *dev, struct kobj_uevent_env *env);
 342        char *(*devnode)(struct device *dev, umode_t *mode);
 343
 344        void (*class_release)(struct class *class);
 345        void (*dev_release)(struct device *dev);
 346
 347        int (*suspend)(struct device *dev, pm_message_t state);
 348        int (*resume)(struct device *dev);
 349
 350        const struct kobj_ns_type_operations *ns_type;
 351        const void *(*namespace)(struct device *dev);
 352
 353        const struct dev_pm_ops *pm;
 354
 355        struct subsys_private *p;
 356};
 357
 358struct class_dev_iter {
 359        struct klist_iter               ki;
 360        const struct device_type        *type;
 361};
 362
 363extern struct kobject *sysfs_dev_block_kobj;
 364extern struct kobject *sysfs_dev_char_kobj;
 365extern int __must_check __class_register(struct class *class,
 366                                         struct lock_class_key *key);
 367extern void class_unregister(struct class *class);
 368
 369/* This is a #define to keep the compiler from merging different
 370 * instances of the __key variable */
 371#define class_register(class)                   \
 372({                                              \
 373        static struct lock_class_key __key;     \
 374        __class_register(class, &__key);        \
 375})
 376
 377struct class_compat;
 378struct class_compat *class_compat_register(const char *name);
 379void class_compat_unregister(struct class_compat *cls);
 380int class_compat_create_link(struct class_compat *cls, struct device *dev,
 381                             struct device *device_link);
 382void class_compat_remove_link(struct class_compat *cls, struct device *dev,
 383                              struct device *device_link);
 384
 385extern void class_dev_iter_init(struct class_dev_iter *iter,
 386                                struct class *class,
 387                                struct device *start,
 388                                const struct device_type *type);
 389extern struct device *class_dev_iter_next(struct class_dev_iter *iter);
 390extern void class_dev_iter_exit(struct class_dev_iter *iter);
 391
 392extern int class_for_each_device(struct class *class, struct device *start,
 393                                 void *data,
 394                                 int (*fn)(struct device *dev, void *data));
 395extern struct device *class_find_device(struct class *class,
 396                                        struct device *start, void *data,
 397                                        int (*match)(struct device *, void *));
 398
 399struct class_attribute {
 400        struct attribute attr;
 401        ssize_t (*show)(struct class *class, struct class_attribute *attr,
 402                        char *buf);
 403        ssize_t (*store)(struct class *class, struct class_attribute *attr,
 404                        const char *buf, size_t count);
 405        const void *(*namespace)(struct class *class,
 406                                 const struct class_attribute *attr);
 407};
 408
 409#define CLASS_ATTR(_name, _mode, _show, _store)                 \
 410struct class_attribute class_attr_##_name = __ATTR(_name, _mode, _show, _store)
 411
 412extern int __must_check class_create_file(struct class *class,
 413                                          const struct class_attribute *attr);
 414extern void class_remove_file(struct class *class,
 415                              const struct class_attribute *attr);
 416
 417/* Simple class attribute that is just a static string */
 418
 419struct class_attribute_string {
 420        struct class_attribute attr;
 421        char *str;
 422};
 423
 424/* Currently read-only only */
 425#define _CLASS_ATTR_STRING(_name, _mode, _str) \
 426        { __ATTR(_name, _mode, show_class_attr_string, NULL), _str }
 427#define CLASS_ATTR_STRING(_name, _mode, _str) \
 428        struct class_attribute_string class_attr_##_name = \
 429                _CLASS_ATTR_STRING(_name, _mode, _str)
 430
 431extern ssize_t show_class_attr_string(struct class *class, struct class_attribute *attr,
 432                        char *buf);
 433
 434struct class_interface {
 435        struct list_head        node;
 436        struct class            *class;
 437
 438        int (*add_dev)          (struct device *, struct class_interface *);
 439        void (*remove_dev)      (struct device *, struct class_interface *);
 440};
 441
 442extern int __must_check class_interface_register(struct class_interface *);
 443extern void class_interface_unregister(struct class_interface *);
 444
 445extern struct class * __must_check __class_create(struct module *owner,
 446                                                  const char *name,
 447                                                  struct lock_class_key *key);
 448extern void class_destroy(struct class *cls);
 449
 450/* This is a #define to keep the compiler from merging different
 451 * instances of the __key variable */
 452#define class_create(owner, name)               \
 453({                                              \
 454        static struct lock_class_key __key;     \
 455        __class_create(owner, name, &__key);    \
 456})
 457
 458/*
 459 * The type of device, "struct device" is embedded in. A class
 460 * or bus can contain devices of different types
 461 * like "partitions" and "disks", "mouse" and "event".
 462 * This identifies the device type and carries type-specific
 463 * information, equivalent to the kobj_type of a kobject.
 464 * If "name" is specified, the uevent will contain it in
 465 * the DEVTYPE variable.
 466 */
 467struct device_type {
 468        const char *name;
 469        const struct attribute_group **groups;
 470        int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
 471        char *(*devnode)(struct device *dev, umode_t *mode);
 472        void (*release)(struct device *dev);
 473
 474        const struct dev_pm_ops *pm;
 475};
 476
 477/* interface for exporting device attributes */
 478struct device_attribute {
 479        struct attribute        attr;
 480        ssize_t (*show)(struct device *dev, struct device_attribute *attr,
 481                        char *buf);
 482        ssize_t (*store)(struct device *dev, struct device_attribute *attr,
 483                         const char *buf, size_t count);
 484};
 485
 486struct dev_ext_attribute {
 487        struct device_attribute attr;
 488        void *var;
 489};
 490
 491ssize_t device_show_ulong(struct device *dev, struct device_attribute *attr,
 492                          char *buf);
 493ssize_t device_store_ulong(struct device *dev, struct device_attribute *attr,
 494                           const char *buf, size_t count);
 495ssize_t device_show_int(struct device *dev, struct device_attribute *attr,
 496                        char *buf);
 497ssize_t device_store_int(struct device *dev, struct device_attribute *attr,
 498                         const char *buf, size_t count);
 499
 500#define DEVICE_ATTR(_name, _mode, _show, _store) \
 501        struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store)
 502#define DEVICE_ULONG_ATTR(_name, _mode, _var) \
 503        struct dev_ext_attribute dev_attr_##_name = \
 504                { __ATTR(_name, _mode, device_show_ulong, device_store_ulong), &(_var) }
 505#define DEVICE_INT_ATTR(_name, _mode, _var) \
 506        struct dev_ext_attribute dev_attr_##_name = \
 507                { __ATTR(_name, _mode, device_show_int, device_store_int), &(_var) }
 508#define DEVICE_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
 509        struct device_attribute dev_attr_##_name =              \
 510                __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
 511
 512extern int device_create_file(struct device *device,
 513                              const struct device_attribute *entry);
 514extern void device_remove_file(struct device *dev,
 515                               const struct device_attribute *attr);
 516extern int __must_check device_create_bin_file(struct device *dev,
 517                                        const struct bin_attribute *attr);
 518extern void device_remove_bin_file(struct device *dev,
 519                                   const struct bin_attribute *attr);
 520extern int device_schedule_callback_owner(struct device *dev,
 521                void (*func)(struct device *dev), struct module *owner);
 522
 523/* This is a macro to avoid include problems with THIS_MODULE */
 524#define device_schedule_callback(dev, func)                     \
 525        device_schedule_callback_owner(dev, func, THIS_MODULE)
 526
 527/* device resource management */
 528typedef void (*dr_release_t)(struct device *dev, void *res);
 529typedef int (*dr_match_t)(struct device *dev, void *res, void *match_data);
 530
 531#ifdef CONFIG_DEBUG_DEVRES
 532extern void *__devres_alloc(dr_release_t release, size_t size, gfp_t gfp,
 533                             const char *name);
 534#define devres_alloc(release, size, gfp) \
 535        __devres_alloc(release, size, gfp, #release)
 536#else
 537extern void *devres_alloc(dr_release_t release, size_t size, gfp_t gfp);
 538#endif
 539extern void devres_free(void *res);
 540extern void devres_add(struct device *dev, void *res);
 541extern void *devres_find(struct device *dev, dr_release_t release,
 542                         dr_match_t match, void *match_data);
 543extern void *devres_get(struct device *dev, void *new_res,
 544                        dr_match_t match, void *match_data);
 545extern void *devres_remove(struct device *dev, dr_release_t release,
 546                           dr_match_t match, void *match_data);
 547extern int devres_destroy(struct device *dev, dr_release_t release,
 548                          dr_match_t match, void *match_data);
 549extern int devres_release(struct device *dev, dr_release_t release,
 550                          dr_match_t match, void *match_data);
 551
 552/* devres group */
 553extern void * __must_check devres_open_group(struct device *dev, void *id,
 554                                             gfp_t gfp);
 555extern void devres_close_group(struct device *dev, void *id);
 556extern void devres_remove_group(struct device *dev, void *id);
 557extern int devres_release_group(struct device *dev, void *id);
 558
 559/* managed kzalloc/kfree for device drivers, no kmalloc, always use kzalloc */
 560extern void *devm_kzalloc(struct device *dev, size_t size, gfp_t gfp);
 561extern void devm_kfree(struct device *dev, void *p);
 562
 563void __iomem *devm_request_and_ioremap(struct device *dev,
 564                        struct resource *res);
 565
 566struct device_dma_parameters {
 567        /*
 568         * a low level driver may set these to teach IOMMU code about
 569         * sg limitations.
 570         */
 571        unsigned int max_segment_size;
 572        unsigned long segment_boundary_mask;
 573};
 574
 575/**
 576 * struct device - The basic device structure
 577 * @parent:     The device's "parent" device, the device to which it is attached.
 578 *              In most cases, a parent device is some sort of bus or host
 579 *              controller. If parent is NULL, the device, is a top-level device,
 580 *              which is not usually what you want.
 581 * @p:          Holds the private data of the driver core portions of the device.
 582 *              See the comment of the struct device_private for detail.
 583 * @kobj:       A top-level, abstract class from which other classes are derived.
 584 * @init_name:  Initial name of the device.
 585 * @type:       The type of device.
 586 *              This identifies the device type and carries type-specific
 587 *              information.
 588 * @mutex:      Mutex to synchronize calls to its driver.
 589 * @bus:        Type of bus device is on.
 590 * @driver:     Which driver has allocated this
 591 * @platform_data: Platform data specific to the device.
 592 *              Example: For devices on custom boards, as typical of embedded
 593 *              and SOC based hardware, Linux often uses platform_data to point
 594 *              to board-specific structures describing devices and how they
 595 *              are wired.  That can include what ports are available, chip
 596 *              variants, which GPIO pins act in what additional roles, and so
 597 *              on.  This shrinks the "Board Support Packages" (BSPs) and
 598 *              minimizes board-specific #ifdefs in drivers.
 599 * @power:      For device power management.
 600 *              See Documentation/power/devices.txt for details.
 601 * @pm_domain:  Provide callbacks that are executed during system suspend,
 602 *              hibernation, system resume and during runtime PM transitions
 603 *              along with subsystem-level and driver-level callbacks.
 604 * @numa_node:  NUMA node this device is close to.
 605 * @dma_mask:   Dma mask (if dma'ble device).
 606 * @coherent_dma_mask: Like dma_mask, but for alloc_coherent mapping as not all
 607 *              hardware supports 64-bit addresses for consistent allocations
 608 *              such descriptors.
 609 * @dma_parms:  A low level driver may set these to teach IOMMU code about
 610 *              segment limitations.
 611 * @dma_pools:  Dma pools (if dma'ble device).
 612 * @dma_mem:    Internal for coherent mem override.
 613 * @archdata:   For arch-specific additions.
 614 * @of_node:    Associated device tree node.
 615 * @devt:       For creating the sysfs "dev".
 616 * @id:         device instance
 617 * @devres_lock: Spinlock to protect the resource of the device.
 618 * @devres_head: The resources list of the device.
 619 * @knode_class: The node used to add the device to the class list.
 620 * @class:      The class of the device.
 621 * @groups:     Optional attribute groups.
 622 * @release:    Callback to free the device after all references have
 623 *              gone away. This should be set by the allocator of the
 624 *              device (i.e. the bus driver that discovered the device).
 625 *
 626 * At the lowest level, every device in a Linux system is represented by an
 627 * instance of struct device. The device structure contains the information
 628 * that the device model core needs to model the system. Most subsystems,
 629 * however, track additional information about the devices they host. As a
 630 * result, it is rare for devices to be represented by bare device structures;
 631 * instead, that structure, like kobject structures, is usually embedded within
 632 * a higher-level representation of the device.
 633 */
 634struct device {
 635        struct device           *parent;
 636
 637        struct device_private   *p;
 638
 639        struct kobject kobj;
 640        const char              *init_name; /* initial name of the device */
 641        const struct device_type *type;
 642
 643        struct mutex            mutex;  /* mutex to synchronize calls to
 644                                         * its driver.
 645                                         */
 646
 647        struct bus_type *bus;           /* type of bus device is on */
 648        struct device_driver *driver;   /* which driver has allocated this
 649                                           device */
 650        void            *platform_data; /* Platform specific data, device
 651                                           core doesn't touch it */
 652        struct dev_pm_info      power;
 653        struct dev_pm_domain    *pm_domain;
 654
 655#ifdef CONFIG_NUMA
 656        int             numa_node;      /* NUMA node this device is close to */
 657#endif
 658        u64             *dma_mask;      /* dma mask (if dma'able device) */
 659        u64             coherent_dma_mask;/* Like dma_mask, but for
 660                                             alloc_coherent mappings as
 661                                             not all hardware supports
 662                                             64 bit addresses for consistent
 663                                             allocations such descriptors. */
 664
 665        struct device_dma_parameters *dma_parms;
 666
 667        struct list_head        dma_pools;      /* dma pools (if dma'ble) */
 668
 669        struct dma_coherent_mem *dma_mem; /* internal for coherent mem
 670                                             override */
 671#ifdef CONFIG_CMA
 672        struct cma *cma_area;           /* contiguous memory area for dma
 673                                           allocations */
 674#endif
 675        /* arch specific additions */
 676        struct dev_archdata     archdata;
 677
 678        struct device_node      *of_node; /* associated device tree node */
 679
 680        dev_t                   devt;   /* dev_t, creates the sysfs "dev" */
 681        u32                     id;     /* device instance */
 682
 683        spinlock_t              devres_lock;
 684        struct list_head        devres_head;
 685
 686        struct klist_node       knode_class;
 687        struct class            *class;
 688        const struct attribute_group **groups;  /* optional groups */
 689
 690        void    (*release)(struct device *dev);
 691        struct iommu_group      *iommu_group;
 692};
 693
 694static inline struct device *kobj_to_dev(struct kobject *kobj)
 695{
 696        return container_of(kobj, struct device, kobj);
 697}
 698
 699/* Get the wakeup routines, which depend on struct device */
 700#include <linux/pm_wakeup.h>
 701
 702static inline const char *dev_name(const struct device *dev)
 703{
 704        /* Use the init name until the kobject becomes available */
 705        if (dev->init_name)
 706                return dev->init_name;
 707
 708        return kobject_name(&dev->kobj);
 709}
 710
 711extern __printf(2, 3)
 712int dev_set_name(struct device *dev, const char *name, ...);
 713
 714#ifdef CONFIG_NUMA
 715static inline int dev_to_node(struct device *dev)
 716{
 717        return dev->numa_node;
 718}
 719static inline void set_dev_node(struct device *dev, int node)
 720{
 721        dev->numa_node = node;
 722}
 723#else
 724static inline int dev_to_node(struct device *dev)
 725{
 726        return -1;
 727}
 728static inline void set_dev_node(struct device *dev, int node)
 729{
 730}
 731#endif
 732
 733static inline struct pm_subsys_data *dev_to_psd(struct device *dev)
 734{
 735        return dev ? dev->power.subsys_data : NULL;
 736}
 737
 738static inline unsigned int dev_get_uevent_suppress(const struct device *dev)
 739{
 740        return dev->kobj.uevent_suppress;
 741}
 742
 743static inline void dev_set_uevent_suppress(struct device *dev, int val)
 744{
 745        dev->kobj.uevent_suppress = val;
 746}
 747
 748static inline int device_is_registered(struct device *dev)
 749{
 750        return dev->kobj.state_in_sysfs;
 751}
 752
 753static inline void device_enable_async_suspend(struct device *dev)
 754{
 755        if (!dev->power.is_prepared)
 756                dev->power.async_suspend = true;
 757}
 758
 759static inline void device_disable_async_suspend(struct device *dev)
 760{
 761        if (!dev->power.is_prepared)
 762                dev->power.async_suspend = false;
 763}
 764
 765static inline bool device_async_suspend_enabled(struct device *dev)
 766{
 767        return !!dev->power.async_suspend;
 768}
 769
 770static inline void pm_suspend_ignore_children(struct device *dev, bool enable)
 771{
 772        dev->power.ignore_children = enable;
 773}
 774
 775static inline void device_lock(struct device *dev)
 776{
 777        mutex_lock(&dev->mutex);
 778}
 779
 780static inline int device_trylock(struct device *dev)
 781{
 782        return mutex_trylock(&dev->mutex);
 783}
 784
 785static inline void device_unlock(struct device *dev)
 786{
 787        mutex_unlock(&dev->mutex);
 788}
 789
 790void driver_init(void);
 791
 792/*
 793 * High level routines for use by the bus drivers
 794 */
 795extern int __must_check device_register(struct device *dev);
 796extern void device_unregister(struct device *dev);
 797extern void device_initialize(struct device *dev);
 798extern int __must_check device_add(struct device *dev);
 799extern void device_del(struct device *dev);
 800extern int device_for_each_child(struct device *dev, void *data,
 801                     int (*fn)(struct device *dev, void *data));
 802extern struct device *device_find_child(struct device *dev, void *data,
 803                                int (*match)(struct device *dev, void *data));
 804extern int device_rename(struct device *dev, const char *new_name);
 805extern int device_move(struct device *dev, struct device *new_parent,
 806                       enum dpm_order dpm_order);
 807extern const char *device_get_devnode(struct device *dev,
 808                                      umode_t *mode, const char **tmp);
 809extern void *dev_get_drvdata(const struct device *dev);
 810extern int dev_set_drvdata(struct device *dev, void *data);
 811
 812/*
 813 * Root device objects for grouping under /sys/devices
 814 */
 815extern struct device *__root_device_register(const char *name,
 816                                             struct module *owner);
 817
 818/*
 819 * This is a macro to avoid include problems with THIS_MODULE,
 820 * just as per what is done for device_schedule_callback() above.
 821 */
 822#define root_device_register(name) \
 823        __root_device_register(name, THIS_MODULE)
 824
 825extern void root_device_unregister(struct device *root);
 826
 827static inline void *dev_get_platdata(const struct device *dev)
 828{
 829        return dev->platform_data;
 830}
 831
 832/*
 833 * Manual binding of a device to driver. See drivers/base/bus.c
 834 * for information on use.
 835 */
 836extern int __must_check device_bind_driver(struct device *dev);
 837extern void device_release_driver(struct device *dev);
 838extern int  __must_check device_attach(struct device *dev);
 839extern int __must_check driver_attach(struct device_driver *drv);
 840extern int __must_check device_reprobe(struct device *dev);
 841
 842/*
 843 * Easy functions for dynamically creating devices on the fly
 844 */
 845extern struct device *device_create_vargs(struct class *cls,
 846                                          struct device *parent,
 847                                          dev_t devt,
 848                                          void *drvdata,
 849                                          const char *fmt,
 850                                          va_list vargs);
 851extern __printf(5, 6)
 852struct device *device_create(struct class *cls, struct device *parent,
 853                             dev_t devt, void *drvdata,
 854                             const char *fmt, ...);
 855extern void device_destroy(struct class *cls, dev_t devt);
 856
 857/*
 858 * Platform "fixup" functions - allow the platform to have their say
 859 * about devices and actions that the general device layer doesn't
 860 * know about.
 861 */
 862/* Notify platform of device discovery */
 863extern int (*platform_notify)(struct device *dev);
 864
 865extern int (*platform_notify_remove)(struct device *dev);
 866
 867
 868/*
 869 * get_device - atomically increment the reference count for the device.
 870 *
 871 */
 872extern struct device *get_device(struct device *dev);
 873extern void put_device(struct device *dev);
 874
 875#ifdef CONFIG_DEVTMPFS
 876extern int devtmpfs_create_node(struct device *dev);
 877extern int devtmpfs_delete_node(struct device *dev);
 878extern int devtmpfs_mount(const char *mntdir);
 879#else
 880static inline int devtmpfs_create_node(struct device *dev) { return 0; }
 881static inline int devtmpfs_delete_node(struct device *dev) { return 0; }
 882static inline int devtmpfs_mount(const char *mountpoint) { return 0; }
 883#endif
 884
 885/* drivers/base/power/shutdown.c */
 886extern void device_shutdown(void);
 887
 888/* debugging and troubleshooting/diagnostic helpers. */
 889extern const char *dev_driver_string(const struct device *dev);
 890
 891
 892#ifdef CONFIG_PRINTK
 893
 894extern int __dev_printk(const char *level, const struct device *dev,
 895                        struct va_format *vaf);
 896extern __printf(3, 4)
 897int dev_printk(const char *level, const struct device *dev,
 898               const char *fmt, ...)
 899        ;
 900extern __printf(2, 3)
 901int dev_emerg(const struct device *dev, const char *fmt, ...);
 902extern __printf(2, 3)
 903int dev_alert(const struct device *dev, const char *fmt, ...);
 904extern __printf(2, 3)
 905int dev_crit(const struct device *dev, const char *fmt, ...);
 906extern __printf(2, 3)
 907int dev_err(const struct device *dev, const char *fmt, ...);
 908extern __printf(2, 3)
 909int dev_warn(const struct device *dev, const char *fmt, ...);
 910extern __printf(2, 3)
 911int dev_notice(const struct device *dev, const char *fmt, ...);
 912extern __printf(2, 3)
 913int _dev_info(const struct device *dev, const char *fmt, ...);
 914
 915#else
 916
 917static inline int __dev_printk(const char *level, const struct device *dev,
 918                               struct va_format *vaf)
 919{ return 0; }
 920static inline __printf(3, 4)
 921int dev_printk(const char *level, const struct device *dev,
 922               const char *fmt, ...)
 923{ return 0; }
 924
 925static inline __printf(2, 3)
 926int dev_emerg(const struct device *dev, const char *fmt, ...)
 927{ return 0; }
 928static inline __printf(2, 3)
 929int dev_crit(const struct device *dev, const char *fmt, ...)
 930{ return 0; }
 931static inline __printf(2, 3)
 932int dev_alert(const struct device *dev, const char *fmt, ...)
 933{ return 0; }
 934static inline __printf(2, 3)
 935int dev_err(const struct device *dev, const char *fmt, ...)
 936{ return 0; }
 937static inline __printf(2, 3)
 938int dev_warn(const struct device *dev, const char *fmt, ...)
 939{ return 0; }
 940static inline __printf(2, 3)
 941int dev_notice(const struct device *dev, const char *fmt, ...)
 942{ return 0; }
 943static inline __printf(2, 3)
 944int _dev_info(const struct device *dev, const char *fmt, ...)
 945{ return 0; }
 946
 947#endif
 948
 949#define dev_level_ratelimited(dev_level, dev, fmt, ...)                 \
 950do {                                                                    \
 951        static DEFINE_RATELIMIT_STATE(_rs,                              \
 952                                      DEFAULT_RATELIMIT_INTERVAL,       \
 953                                      DEFAULT_RATELIMIT_BURST);         \
 954        if (__ratelimit(&_rs))                                          \
 955                dev_level(dev, fmt, ##__VA_ARGS__);                     \
 956} while (0)
 957
 958#define dev_emerg_ratelimited(dev, fmt, ...)                            \
 959        dev_level_ratelimited(dev_emerg, dev, fmt, ##__VA_ARGS__)
 960#define dev_alert_ratelimited(dev, fmt, ...)                            \
 961        dev_level_ratelimited(dev_alert, dev, fmt, ##__VA_ARGS__)
 962#define dev_crit_ratelimited(dev, fmt, ...)                             \
 963        dev_level_ratelimited(dev_crit, dev, fmt, ##__VA_ARGS__)
 964#define dev_err_ratelimited(dev, fmt, ...)                              \
 965        dev_level_ratelimited(dev_err, dev, fmt, ##__VA_ARGS__)
 966#define dev_warn_ratelimited(dev, fmt, ...)                             \
 967        dev_level_ratelimited(dev_warn, dev, fmt, ##__VA_ARGS__)
 968#define dev_notice_ratelimited(dev, fmt, ...)                           \
 969        dev_level_ratelimited(dev_notice, dev, fmt, ##__VA_ARGS__)
 970#define dev_info_ratelimited(dev, fmt, ...)                             \
 971        dev_level_ratelimited(dev_info, dev, fmt, ##__VA_ARGS__)
 972#define dev_dbg_ratelimited(dev, fmt, ...)                              \
 973        dev_level_ratelimited(dev_dbg, dev, fmt, ##__VA_ARGS__)
 974
 975/*
 976 * Stupid hackaround for existing uses of non-printk uses dev_info
 977 *
 978 * Note that the definition of dev_info below is actually _dev_info
 979 * and a macro is used to avoid redefining dev_info
 980 */
 981
 982#define dev_info(dev, fmt, arg...) _dev_info(dev, fmt, ##arg)
 983
 984#if defined(CONFIG_DYNAMIC_DEBUG)
 985#define dev_dbg(dev, format, ...)                    \
 986do {                                                 \
 987        dynamic_dev_dbg(dev, format, ##__VA_ARGS__); \
 988} while (0)
 989#elif defined(DEBUG)
 990#define dev_dbg(dev, format, arg...)            \
 991        dev_printk(KERN_DEBUG, dev, format, ##arg)
 992#else
 993#define dev_dbg(dev, format, arg...)                            \
 994({                                                              \
 995        if (0)                                                  \
 996                dev_printk(KERN_DEBUG, dev, format, ##arg);     \
 997        0;                                                      \
 998})
 999#endif
1000
1001#ifdef VERBOSE_DEBUG
1002#define dev_vdbg        dev_dbg
1003#else
1004#define dev_vdbg(dev, format, arg...)                           \
1005({                                                              \
1006        if (0)                                                  \
1007                dev_printk(KERN_DEBUG, dev, format, ##arg);     \
1008        0;                                                      \
1009})
1010#endif
1011
1012/*
1013 * dev_WARN*() acts like dev_printk(), but with the key difference
1014 * of using a WARN/WARN_ON to get the message out, including the
1015 * file/line information and a backtrace.
1016 */
1017#define dev_WARN(dev, format, arg...) \
1018        WARN(1, "Device: %s\n" format, dev_driver_string(dev), ## arg);
1019
1020#define dev_WARN_ONCE(dev, condition, format, arg...) \
1021        WARN_ONCE(condition, "Device %s\n" format, \
1022                        dev_driver_string(dev), ## arg)
1023
1024/* Create alias, so I can be autoloaded. */
1025#define MODULE_ALIAS_CHARDEV(major,minor) \
1026        MODULE_ALIAS("char-major-" __stringify(major) "-" __stringify(minor))
1027#define MODULE_ALIAS_CHARDEV_MAJOR(major) \
1028        MODULE_ALIAS("char-major-" __stringify(major) "-*")
1029
1030#ifdef CONFIG_SYSFS_DEPRECATED
1031extern long sysfs_deprecated;
1032#else
1033#define sysfs_deprecated 0
1034#endif
1035
1036/**
1037 * module_driver() - Helper macro for drivers that don't do anything
1038 * special in module init/exit. This eliminates a lot of boilerplate.
1039 * Each module may only use this macro once, and calling it replaces
1040 * module_init() and module_exit().
1041 *
1042 * @__driver: driver name
1043 * @__register: register function for this driver type
1044 * @__unregister: unregister function for this driver type
1045 * @...: Additional arguments to be passed to __register and __unregister.
1046 *
1047 * Use this macro to construct bus specific macros for registering
1048 * drivers, and do not use it on its own.
1049 */
1050#define module_driver(__driver, __register, __unregister, ...) \
1051static int __init __driver##_init(void) \
1052{ \
1053        return __register(&(__driver) , ##__VA_ARGS__); \
1054} \
1055module_init(__driver##_init); \
1056static void __exit __driver##_exit(void) \
1057{ \
1058        __unregister(&(__driver) , ##__VA_ARGS__); \
1059} \
1060module_exit(__driver##_exit);
1061
1062#endif /* _DEVICE_H_ */
1063
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