总线（bus）;设备（devices）;驱动（drivers）

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Linux/include/linux/device.h

   /*
    * device.h - generic, centralized driver model
    *
    * Copyright (c) 2001-2003 Patrick Mochel <mochel@osdl.org>
    * Copyright (c) 2004-2009 Greg Kroah-Hartman <gregkh@suse.de>
    * Copyright (c) 2008-2009 Novell Inc.
    *
    * This file is released under the GPLv2
    *
   * See Documentation/driver-model/ for more information.
   */
  
  #ifndef _DEVICE_H_
  #define _DEVICE_H_
  
  #include <linux/ioport.h>
  #include <linux/kobject.h>
  #include <linux/klist.h>
  #include <linux/list.h>
  #include <linux/lockdep.h>
  #include <linux/compiler.h>
  #include <linux/types.h>
  #include <linux/mutex.h>
  #include <linux/pinctrl/devinfo.h>
  #include <linux/pm.h>
  #include <linux/atomic.h>
  #include <linux/ratelimit.h>
  #include <linux/uidgid.h>
  #include <linux/gfp.h>
  #include <asm/device.h>
  
  struct device;
  struct device_private;
  struct device_driver;
  struct driver_private;
  struct module;
  struct class;
  struct subsys_private;
  struct bus_type;
  struct device_node;
  struct fwnode_handle;
  struct iommu_ops;
  struct iommu_group;
  
  struct bus_attribute {
          struct attribute        attr;
          ssize_t (*show)(struct bus_type *bus, char *buf);
          ssize_t (*store)(struct bus_type *bus, const char *buf, size_t count);
  };
  
  #define BUS_ATTR(_name, _mode, _show, _store)   \
          struct bus_attribute bus_attr_##_name = __ATTR(_name, _mode, _show, _store)
  #define BUS_ATTR_RW(_name) \
          struct bus_attribute bus_attr_##_name = __ATTR_RW(_name)
  #define BUS_ATTR_RO(_name) \
          struct bus_attribute bus_attr_##_name = __ATTR_RO(_name)
  
  extern int __must_check bus_create_file(struct bus_type *,
                                          struct bus_attribute *);
  extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
  
  /**
   * struct bus_type - The bus type of the device
   *
   * @name:       The name of the bus.
   * @dev_name:   Used for subsystems to enumerate devices like ("foo%u", dev->id).
   * @dev_root:   Default device to use as the parent.
   * @dev_attrs:  Default attributes of the devices on the bus.
   * @bus_groups: Default attributes of the bus.
   * @dev_groups: Default attributes of the devices on the bus.
   * @drv_groups: Default attributes of the device drivers on the bus.
   * @match:      Called, perhaps multiple times, whenever a new device or driver
   *              is added for this bus. It should return a nonzero value if the
   *              given device can be handled by the given driver.
   * @uevent:     Called when a device is added, removed, or a few other things
   *              that generate uevents to add the environment variables.
   * @probe:      Called when a new device or driver add to this bus, and callback
   *              the specific driver's probe to initial the matched device.
   * @remove:     Called when a device removed from this bus.
   * @shutdown:   Called at shut-down time to quiesce the device.
   *
   * @online:     Called to put the device back online (after offlining it).
   * @offline:    Called to put the device offline for hot-removal. May fail.
   *
   * @suspend:    Called when a device on this bus wants to go to sleep mode.
   * @resume:     Called to bring a device on this bus out of sleep mode.
   * @pm:         Power management operations of this bus, callback the specific
   *              device driver's pm-ops.
   * @iommu_ops:  IOMMU specific operations for this bus, used to attach IOMMU
   *              driver implementations to a bus and allow the driver to do
   *              bus-specific setup
   * @p:          The private data of the driver core, only the driver core can
   *              touch this.
   * @lock_key:   Lock class key for use by the lock validator
   *
   * A bus is a channel between the processor and one or more devices. For the
   * purposes of the device model, all devices are connected via a bus, even if
   * it is an internal, virtual, "platform" bus. Buses can plug into each other.
   * A USB controller is usually a PCI device, for example. The device model
  * represents the actual connections between buses and the devices they control.
  * A bus is represented by the bus_type structure. It contains the name, the
  * default attributes, the bus' methods, PM operations, and the driver core's
  * private data.
  */
 struct bus_type {
106         const char              *name;
107         const char              *dev_name;
108         struct device           *dev_root;
109         struct device_attribute *dev_attrs;     /* use dev_groups instead */
110         const struct attribute_group **bus_groups;
111         const struct attribute_group **dev_groups;
112         const struct attribute_group **drv_groups;
113 
114         int (*match)(struct device *dev, struct device_driver *drv);
115         int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
116         int (*probe)(struct device *dev);
117         int (*remove)(struct device *dev);
118         void (*shutdown)(struct device *dev);
119 
120         int (*online)(struct device *dev);
121         int (*offline)(struct device *dev);
122 
123         int (*suspend)(struct device *dev, pm_message_t state);
124         int (*resume)(struct device *dev);
125 
126         const struct dev_pm_ops *pm;
127 
128         const struct iommu_ops *iommu_ops;
129 
130         struct subsys_private *p;
131         struct lock_class_key lock_key;
132 };
 
 extern int __must_check bus_register(struct bus_type *bus);
 
 extern void bus_unregister(struct bus_type *bus);
 
 extern int __must_check bus_rescan_devices(struct bus_type *bus);
 
 /* iterator helpers for buses */
 struct subsys_dev_iter {
         struct klist_iter               ki;
         const struct device_type        *type;
 };
 void subsys_dev_iter_init(struct subsys_dev_iter *iter,
                          struct bus_type *subsys,
                          struct device *start,
                          const struct device_type *type);
 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter);
 void subsys_dev_iter_exit(struct subsys_dev_iter *iter);
 
 int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data,
                      int (*fn)(struct device *dev, void *data));
 struct device *bus_find_device(struct bus_type *bus, struct device *start,
                                void *data,
                                int (*match)(struct device *dev, void *data));
 struct device *bus_find_device_by_name(struct bus_type *bus,
                                        struct device *start,
                                        const char *name);
 struct device *subsys_find_device_by_id(struct bus_type *bus, unsigned int id,
                                         struct device *hint);
 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
                      void *data, int (*fn)(struct device_driver *, void *));
 void bus_sort_breadthfirst(struct bus_type *bus,
                            int (*compare)(const struct device *a,
                                           const struct device *b));
 /*
  * Bus notifiers: Get notified of addition/removal of devices
  * and binding/unbinding of drivers to devices.
  * In the long run, it should be a replacement for the platform
  * notify hooks.
  */
 struct notifier_block;
 
 extern int bus_register_notifier(struct bus_type *bus,
                                  struct notifier_block *nb);
 extern int bus_unregister_notifier(struct bus_type *bus,
                                    struct notifier_block *nb);
 
 /* All 4 notifers below get called with the target struct device *
  * as an argument. Note that those functions are likely to be called
  * with the device lock held in the core, so be careful.
  */
 #define BUS_NOTIFY_ADD_DEVICE           0x00000001 /* device added */
 #define BUS_NOTIFY_DEL_DEVICE           0x00000002 /* device to be removed */
 #define BUS_NOTIFY_REMOVED_DEVICE       0x00000003 /* device removed */
 #define BUS_NOTIFY_BIND_DRIVER          0x00000004 /* driver about to be
                                                       bound */
 #define BUS_NOTIFY_BOUND_DRIVER         0x00000005 /* driver bound to device */
 #define BUS_NOTIFY_UNBIND_DRIVER        0x00000006 /* driver about to be
                                                       unbound */
 #define BUS_NOTIFY_UNBOUND_DRIVER       0x00000007 /* driver is unbound
                                                       from the device */
 
 extern struct kset *bus_get_kset(struct bus_type *bus);
 extern struct klist *bus_get_device_klist(struct bus_type *bus);
 
 /**
  * struct device_driver - The basic device driver structure
  * @name:       Name of the device driver.
  * @bus:        The bus which the device of this driver belongs to.
  * @owner:      The module owner.
  * @mod_name:   Used for built-in modules.
  * @suppress_bind_attrs: Disables bind/unbind via sysfs.
  * @of_match_table: The open firmware table.
  * @acpi_match_table: The ACPI match table.
  * @probe:      Called to query the existence of a specific device,
  *              whether this driver can work with it, and bind the driver
  *              to a specific device.
  * @remove:     Called when the device is removed from the system to
  *              unbind a device from this driver.
  * @shutdown:   Called at shut-down time to quiesce the device.
  * @suspend:    Called to put the device to sleep mode. Usually to a
  *              low power state.
  * @resume:     Called to bring a device from sleep mode.
  * @groups:     Default attributes that get created by the driver core
  *              automatically.
  * @pm:         Power management operations of the device which matched
  *              this driver.
  * @p:          Driver core's private data, no one other than the driver
  *              core can touch this.
  *
  * The device driver-model tracks all of the drivers known to the system.
  * The main reason for this tracking is to enable the driver core to match
  * up drivers with new devices. Once drivers are known objects within the
  * system, however, a number of other things become possible. Device drivers
  * can export information and configuration variables that are independent
  * of any specific device.
  */
 struct device_driver {
231         const char              *name;
232         struct bus_type         *bus;
233 
234         struct module           *owner;
235         const char              *mod_name;      /* used for built-in modules */
236 
237         bool suppress_bind_attrs;       /* disables bind/unbind via sysfs */
238 
239         const struct of_device_id       *of_match_table;
240         const struct acpi_device_id     *acpi_match_table;
241 
242         int (*probe) (struct device *dev);
243         int (*remove) (struct device *dev);
244         void (*shutdown) (struct device *dev);
245         int (*suspend) (struct device *dev, pm_message_t state);
246         int (*resume) (struct device *dev);
247         const struct attribute_group **groups;
248 
249         const struct dev_pm_ops *pm;
250 
251         struct driver_private *p;
252 };
 
 
 extern int __must_check driver_register(struct device_driver *drv);
 extern void driver_unregister(struct device_driver *drv);
 
 extern struct device_driver *driver_find(const char *name,
                                          struct bus_type *bus);
 extern int driver_probe_done(void);
 extern void wait_for_device_probe(void);
 
 
 /* sysfs interface for exporting driver attributes */
 
 struct driver_attribute {
         struct attribute attr;
         ssize_t (*show)(struct device_driver *driver, char *buf);
         ssize_t (*store)(struct device_driver *driver, const char *buf,
                          size_t count);
 };
 
 #define DRIVER_ATTR(_name, _mode, _show, _store) \
         struct driver_attribute driver_attr_##_name = __ATTR(_name, _mode, _show, _store)
 #define DRIVER_ATTR_RW(_name) \
         struct driver_attribute driver_attr_##_name = __ATTR_RW(_name)
 #define DRIVER_ATTR_RO(_name) \
         struct driver_attribute driver_attr_##_name = __ATTR_RO(_name)
 #define DRIVER_ATTR_WO(_name) \
         struct driver_attribute driver_attr_##_name = __ATTR_WO(_name)
 
 extern int __must_check driver_create_file(struct device_driver *driver,
                                         const struct driver_attribute *attr);
 extern void driver_remove_file(struct device_driver *driver,
                                const struct driver_attribute *attr);
 
 extern int __must_check driver_for_each_device(struct device_driver *drv,
                                                struct device *start,
                                                void *data,
                                                int (*fn)(struct device *dev,
                                                          void *));
 struct device *driver_find_device(struct device_driver *drv,
                                   struct device *start, void *data,
                                   int (*match)(struct device *dev, void *data));
 
 /**
  * struct subsys_interface - interfaces to device functions
  * @name:       name of the device function
  * @subsys:     subsytem of the devices to attach to
  * @node:       the list of functions registered at the subsystem
  * @add_dev:    device hookup to device function handler
  * @remove_dev: device hookup to device function handler
  *
  * Simple interfaces attached to a subsystem. Multiple interfaces can
  * attach to a subsystem and its devices. Unlike drivers, they do not
  * exclusively claim or control devices. Interfaces usually represent
  * a specific functionality of a subsystem/class of devices.
  */
 struct subsys_interface {
         const char *name;
         struct bus_type *subsys;
         struct list_head node;
         int (*add_dev)(struct device *dev, struct subsys_interface *sif);
         int (*remove_dev)(struct device *dev, struct subsys_interface *sif);
 };
 
 int subsys_interface_register(struct subsys_interface *sif);
 void subsys_interface_unregister(struct subsys_interface *sif);
 
 int subsys_system_register(struct bus_type *subsys,
                            const struct attribute_group **groups);
 int subsys_virtual_register(struct bus_type *subsys,
                             const struct attribute_group **groups);
 
 /**
  * struct class - device classes
  * @name:       Name of the class.
  * @owner:      The module owner.
  * @class_attrs: Default attributes of this class.
  * @dev_groups: Default attributes of the devices that belong to the class.
  * @dev_kobj:   The kobject that represents this class and links it into the hierarchy.
  * @dev_uevent: Called when a device is added, removed from this class, or a
  *              few other things that generate uevents to add the environment
  *              variables.
  * @devnode:    Callback to provide the devtmpfs.
  * @class_release: Called to release this class.
  * @dev_release: Called to release the device.
  * @suspend:    Used to put the device to sleep mode, usually to a low power
  *              state.
  * @resume:     Used to bring the device from the sleep mode.
  * @ns_type:    Callbacks so sysfs can detemine namespaces.
  * @namespace:  Namespace of the device belongs to this class.
  * @pm:         The default device power management operations of this class.
  * @p:          The private data of the driver core, no one other than the
  *              driver core can touch this.
  *
  * A class is a higher-level view of a device that abstracts out low-level
  * implementation details. Drivers may see a SCSI disk or an ATA disk, but,
  * at the class level, they are all simply disks. Classes allow user space
  * to work with devices based on what they do, rather than how they are
  * connected or how they work.
  */
 struct class {
         const char              *name;
         struct module           *owner;
 
         struct class_attribute          *class_attrs;
         const struct attribute_group    **dev_groups;
         struct kobject                  *dev_kobj;
 
         int (*dev_uevent)(struct device *dev, struct kobj_uevent_env *env);
         char *(*devnode)(struct device *dev, umode_t *mode);
 
         void (*class_release)(struct class *class);
         void (*dev_release)(struct device *dev);
 
         int (*suspend)(struct device *dev, pm_message_t state);
         int (*resume)(struct device *dev);
 
         const struct kobj_ns_type_operations *ns_type;
         const void *(*namespace)(struct device *dev);
 
         const struct dev_pm_ops *pm;
 
         struct subsys_private *p;
 };
 
 struct class_dev_iter {
         struct klist_iter               ki;
         const struct device_type        *type;
 };
 
 extern struct kobject *sysfs_dev_block_kobj;
 extern struct kobject *sysfs_dev_char_kobj;
 extern int __must_check __class_register(struct class *class,
                                          struct lock_class_key *key);
 extern void class_unregister(struct class *class);
 
 /* This is a #define to keep the compiler from merging different
  * instances of the __key variable */
 #define class_register(class)                   \
 ({                                              \
         static struct lock_class_key __key;     \
         __class_register(class, &__key);        \
 })
 
 struct class_compat;
 struct class_compat *class_compat_register(const char *name);
 void class_compat_unregister(struct class_compat *cls);
 int class_compat_create_link(struct class_compat *cls, struct device *dev,
                              struct device *device_link);
 void class_compat_remove_link(struct class_compat *cls, struct device *dev,
                               struct device *device_link);
 
 extern void class_dev_iter_init(struct class_dev_iter *iter,
                                 struct class *class,
                                 struct device *start,
                                 const struct device_type *type);
 extern struct device *class_dev_iter_next(struct class_dev_iter *iter);
 extern void class_dev_iter_exit(struct class_dev_iter *iter);
 
 extern int class_for_each_device(struct class *class, struct device *start,
                                  void *data,
                                  int (*fn)(struct device *dev, void *data));
 extern struct device *class_find_device(struct class *class,
                                         struct device *start, const void *data,
                                         int (*match)(struct device *, const void *));
 
 struct class_attribute {
         struct attribute attr;
         ssize_t (*show)(struct class *class, struct class_attribute *attr,
                         char *buf);
         ssize_t (*store)(struct class *class, struct class_attribute *attr,
                         const char *buf, size_t count);
 };
 
 #define CLASS_ATTR(_name, _mode, _show, _store) \
         struct class_attribute class_attr_##_name = __ATTR(_name, _mode, _show, _store)
 #define CLASS_ATTR_RW(_name) \
         struct class_attribute class_attr_##_name = __ATTR_RW(_name)
 #define CLASS_ATTR_RO(_name) \
         struct class_attribute class_attr_##_name = __ATTR_RO(_name)
 
 extern int __must_check class_create_file_ns(struct class *class,
                                              const struct class_attribute *attr,
                                              const void *ns);
 extern void class_remove_file_ns(struct class *class,
                                  const struct class_attribute *attr,
                                  const void *ns);
 
 static inline int __must_check class_create_file(struct class *class,
                                         const struct class_attribute *attr)
 {
         return class_create_file_ns(class, attr, NULL);
 }
 
 static inline void class_remove_file(struct class *class,
                                      const struct class_attribute *attr)
 {
         return class_remove_file_ns(class, attr, NULL);
 }
 
 /* Simple class attribute that is just a static string */
 struct class_attribute_string {
         struct class_attribute attr;
         char *str;
 };
 
 /* Currently read-only only */
 #define _CLASS_ATTR_STRING(_name, _mode, _str) \
         { __ATTR(_name, _mode, show_class_attr_string, NULL), _str }
 #define CLASS_ATTR_STRING(_name, _mode, _str) \
         struct class_attribute_string class_attr_##_name = \
                 _CLASS_ATTR_STRING(_name, _mode, _str)
 
 extern ssize_t show_class_attr_string(struct class *class, struct class_attribute *attr,
                         char *buf);
 
 struct class_interface {
         struct list_head        node;
         struct class            *class;
 
         int (*add_dev)          (struct device *, struct class_interface *);
         void (*remove_dev)      (struct device *, struct class_interface *);
 };
 
 extern int __must_check class_interface_register(struct class_interface *);
 extern void class_interface_unregister(struct class_interface *);
 
 extern struct class * __must_check __class_create(struct module *owner,
                                                   const char *name,
                                                   struct lock_class_key *key);
 extern void class_destroy(struct class *cls);
 
 /* This is a #define to keep the compiler from merging different
  * instances of the __key variable */
 #define class_create(owner, name)               \
 ({                                              \
         static struct lock_class_key __key;     \
         __class_create(owner, name, &__key);    \
 })
 
 /*
  * The type of device, "struct device" is embedded in. A class
  * or bus can contain devices of different types
  * like "partitions" and "disks", "mouse" and "event".
  * This identifies the device type and carries type-specific
  * information, equivalent to the kobj_type of a kobject.
  * If "name" is specified, the uevent will contain it in
  * the DEVTYPE variable.
  */
 struct device_type {
503         const char *name;
504         const struct attribute_group **groups;
505         int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
506         char *(*devnode)(struct device *dev, umode_t *mode,
507                          kuid_t *uid, kgid_t *gid);
508         void (*release)(struct device *dev);
509 
510         const struct dev_pm_ops *pm;
511 };
512 
 /* interface for exporting device attributes */
 struct device_attribute {
         struct attribute        attr;
         ssize_t (*show)(struct device *dev, struct device_attribute *attr,
                         char *buf);
         ssize_t (*store)(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count);
 };
 
 struct dev_ext_attribute {
         struct device_attribute attr;
         void *var;
 };
 
 ssize_t device_show_ulong(struct device *dev, struct device_attribute *attr,
                           char *buf);
 ssize_t device_store_ulong(struct device *dev, struct device_attribute *attr,
                            const char *buf, size_t count);
 ssize_t device_show_int(struct device *dev, struct device_attribute *attr,
                         char *buf);
 ssize_t device_store_int(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count);
 ssize_t device_show_bool(struct device *dev, struct device_attribute *attr,
                         char *buf);
 ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count);
 
 #define DEVICE_ATTR(_name, _mode, _show, _store) \
         struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store)
 #define DEVICE_ATTR_RW(_name) \
         struct device_attribute dev_attr_##_name = __ATTR_RW(_name)
 #define DEVICE_ATTR_RO(_name) \
         struct device_attribute dev_attr_##_name = __ATTR_RO(_name)
 #define DEVICE_ATTR_WO(_name) \
         struct device_attribute dev_attr_##_name = __ATTR_WO(_name)
 #define DEVICE_ULONG_ATTR(_name, _mode, _var) \
         struct dev_ext_attribute dev_attr_##_name = \
                 { __ATTR(_name, _mode, device_show_ulong, device_store_ulong), &(_var) }
 #define DEVICE_INT_ATTR(_name, _mode, _var) \
         struct dev_ext_attribute dev_attr_##_name = \
                 { __ATTR(_name, _mode, device_show_int, device_store_int), &(_var) }
 #define DEVICE_BOOL_ATTR(_name, _mode, _var) \
         struct dev_ext_attribute dev_attr_##_name = \
                 { __ATTR(_name, _mode, device_show_bool, device_store_bool), &(_var) }
 #define DEVICE_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
         struct device_attribute dev_attr_##_name =              \
                 __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
 
 extern int device_create_file(struct device *device,
                               const struct device_attribute *entry);
 extern void device_remove_file(struct device *dev,
                                const struct device_attribute *attr);
 extern bool device_remove_file_self(struct device *dev,
                                     const struct device_attribute *attr);
 extern int __must_check device_create_bin_file(struct device *dev,
                                         const struct bin_attribute *attr);
 extern void device_remove_bin_file(struct device *dev,
                                    const struct bin_attribute *attr);
 
 /* device resource management */
 typedef void (*dr_release_t)(struct device *dev, void *res);
 typedef int (*dr_match_t)(struct device *dev, void *res, void *match_data);
 
 #ifdef CONFIG_DEBUG_DEVRES
 extern void *__devres_alloc(dr_release_t release, size_t size, gfp_t gfp,
                              const char *name);
 #define devres_alloc(release, size, gfp) \
         __devres_alloc(release, size, gfp, #release)
 #else
 extern void *devres_alloc(dr_release_t release, size_t size, gfp_t gfp);
 #endif
 extern void devres_for_each_res(struct device *dev, dr_release_t release,
                                 dr_match_t match, void *match_data,
                                 void (*fn)(struct device *, void *, void *),
                                 void *data);
 extern void devres_free(void *res);
 extern void devres_add(struct device *dev, void *res);
 extern void *devres_find(struct device *dev, dr_release_t release,
                          dr_match_t match, void *match_data);
 extern void *devres_get(struct device *dev, void *new_res,
                         dr_match_t match, void *match_data);
 extern void *devres_remove(struct device *dev, dr_release_t release,
                            dr_match_t match, void *match_data);
 extern int devres_destroy(struct device *dev, dr_release_t release,
                           dr_match_t match, void *match_data);
 extern int devres_release(struct device *dev, dr_release_t release,
                           dr_match_t match, void *match_data);
 
 /* devres group */
 extern void * __must_check devres_open_group(struct device *dev, void *id,
                                              gfp_t gfp);
 extern void devres_close_group(struct device *dev, void *id);
 extern void devres_remove_group(struct device *dev, void *id);
 extern int devres_release_group(struct device *dev, void *id);
 
 /* managed devm_k.alloc/kfree for device drivers */
 extern void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp);
 extern char *devm_kvasprintf(struct device *dev, gfp_t gfp, const char *fmt,
                              va_list ap);
 extern __printf(3, 4)
 char *devm_kasprintf(struct device *dev, gfp_t gfp, const char *fmt, ...);
 static inline void *devm_kzalloc(struct device *dev, size_t size, gfp_t gfp)
 {
         return devm_kmalloc(dev, size, gfp | __GFP_ZERO);
 }
 static inline void *devm_kmalloc_array(struct device *dev,
                                        size_t n, size_t size, gfp_t flags)
 {
         if (size != 0 && n > SIZE_MAX / size)
                 return NULL;
         return devm_kmalloc(dev, n * size, flags);
 }
 static inline void *devm_kcalloc(struct device *dev,
                                  size_t n, size_t size, gfp_t flags)
 {
         return devm_kmalloc_array(dev, n, size, flags | __GFP_ZERO);
 }
 extern void devm_kfree(struct device *dev, void *p);
 extern char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp);
 extern void *devm_kmemdup(struct device *dev, const void *src, size_t len,
                           gfp_t gfp);
 
 extern unsigned long devm_get_free_pages(struct device *dev,
                                          gfp_t gfp_mask, unsigned int order);
 extern void devm_free_pages(struct device *dev, unsigned long addr);
 
 void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res);
 
 /* allows to add/remove a custom action to devres stack */
 int devm_add_action(struct device *dev, void (*action)(void *), void *data);
 void devm_remove_action(struct device *dev, void (*action)(void *), void *data);
 
 struct device_dma_parameters {
         /*
          * a low level driver may set these to teach IOMMU code about
          * sg limitations.
          */
         unsigned int max_segment_size;
         unsigned long segment_boundary_mask;
 };
 
 /**
  * struct device - The basic device structure
  * @parent:     The device's "parent" device, the device to which it is attached.
  *              In most cases, a parent device is some sort of bus or host
  *              controller. If parent is NULL, the device, is a top-level device,
  *              which is not usually what you want.
  * @p:          Holds the private data of the driver core portions of the device.
  *              See the comment of the struct device_private for detail.
  * @kobj:       A top-level, abstract class from which other classes are derived.
  * @init_name:  Initial name of the device.
  * @type:       The type of device.
  *              This identifies the device type and carries type-specific
  *              information.
  * @mutex:      Mutex to synchronize calls to its driver.
  * @bus:        Type of bus device is on.
  * @driver:     Which driver has allocated this
  * @platform_data: Platform data specific to the device.
  *              Example: For devices on custom boards, as typical of embedded
  *              and SOC based hardware, Linux often uses platform_data to point
  *              to board-specific structures describing devices and how they
  *              are wired.  That can include what ports are available, chip
  *              variants, which GPIO pins act in what additional roles, and so
  *              on.  This shrinks the "Board Support Packages" (BSPs) and
  *              minimizes board-specific #ifdefs in drivers.
  * @driver_data: Private pointer for driver specific info.
  * @power:      For device power management.
  *              See Documentation/power/devices.txt for details.
  * @pm_domain:  Provide callbacks that are executed during system suspend,
  *              hibernation, system resume and during runtime PM transitions
  *              along with subsystem-level and driver-level callbacks.
  * @pins:       For device pin management.
  *              See Documentation/pinctrl.txt for details.
  * @numa_node:  NUMA node this device is close to.
  * @dma_mask:   Dma mask (if dma'ble device).
  * @coherent_dma_mask: Like dma_mask, but for alloc_coherent mapping as not all
  *              hardware supports 64-bit addresses for consistent allocations
  *              such descriptors.
  * @dma_pfn_offset: offset of DMA memory range relatively of RAM
  * @dma_parms:  A low level driver may set these to teach IOMMU code about
  *              segment limitations.
  * @dma_pools:  Dma pools (if dma'ble device).
  * @dma_mem:    Internal for coherent mem override.
  * @cma_area:   Contiguous memory area for dma allocations
  * @archdata:   For arch-specific additions.
  * @of_node:    Associated device tree node.
  * @fwnode:     Associated device node supplied by platform firmware.
  * @devt:       For creating the sysfs "dev".
  * @id:         device instance
  * @devres_lock: Spinlock to protect the resource of the device.
  * @devres_head: The resources list of the device.
  * @knode_class: The node used to add the device to the class list.
  * @class:      The class of the device.
  * @groups:     Optional attribute groups.
  * @release:    Callback to free the device after all references have
  *              gone away. This should be set by the allocator of the
  *              device (i.e. the bus driver that discovered the device).
  * @iommu_group: IOMMU group the device belongs to.
  *
  * @offline_disabled: If set, the device is permanently online.
  * @offline:    Set after successful invocation of bus type's .offline().
  *
  * At the lowest level, every device in a Linux system is represented by an
  * instance of struct device. The device structure contains the information
  * that the device model core needs to model the system. Most subsystems,
  * however, track additional information about the devices they host. As a
  * result, it is rare for devices to be represented by bare device structures;
  * instead, that structure, like kobject structures, is usually embedded within
  * a higher-level representation of the device.
  */
723 struct device {
724         struct device           *parent;
725 
726         struct device_private   *p;
727 
728         struct kobject kobj;
729         const char              *init_name; /* initial name of the device */
730         const struct device_type *type;
731 
732         struct mutex            mutex;  /* mutex to synchronize calls to
733                                          * its driver.
734                                          */
735 
736         struct bus_type *bus;           /* type of bus device is on */
737         struct device_driver *driver;   /* which driver has allocated this
738                                            device */
739         void            *platform_data; /* Platform specific data, device
740                                            core doesn't touch it */
741         void            *driver_data;   /* Driver data, set and get with
742                                            dev_set/get_drvdata */
743         struct dev_pm_info      power;
744         struct dev_pm_domain    *pm_domain;
745 
746 #ifdef CONFIG_PINCTRL
747         struct dev_pin_info     *pins;
748 #endif
749 
750 #ifdef CONFIG_NUMA
751         int             numa_node;      /* NUMA node this device is close to */
752 #endif
753         u64             *dma_mask;      /* dma mask (if dma'able device) */
754         u64             coherent_dma_mask;/* Like dma_mask, but for
755                                              alloc_coherent mappings as
756                                              not all hardware supports
757                                              64 bit addresses for consistent
758                                              allocations such descriptors. */
759         unsigned long   dma_pfn_offset;
760 
761         struct device_dma_parameters *dma_parms;
762 
763         struct list_head        dma_pools;      /* dma pools (if dma'ble) */
764 
765         struct dma_coherent_mem *dma_mem; /* internal for coherent mem
766                                              override */
767 #ifdef CONFIG_DMA_CMA
768         struct cma *cma_area;           /* contiguous memory area for dma
769                                            allocations */
770 #endif
771         /* arch specific additions */
772         struct dev_archdata     archdata;
773 
774         struct device_node      *of_node; /* associated device tree node */
775         struct fwnode_handle    *fwnode; /* firmware device node */
776 
777         dev_t                   devt;   /* dev_t, creates the sysfs "dev" */
778         u32                     id;     /* device instance */
779 
780         spinlock_t              devres_lock;
781         struct list_head        devres_head;
782 
783         struct klist_node       knode_class;
784         struct class            *class;
785         const struct attribute_group **groups;  /* optional groups */
786 
787         void    (*release)(struct device *dev);
788         struct iommu_group      *iommu_group;
789 
790         bool                    offline_disabled:1;
791         bool                    offline:1;
792 };
 
 static inline struct device *kobj_to_dev(struct kobject *kobj)
 {
         return container_of(kobj, struct device, kobj);
 }
 
 /* Get the wakeup routines, which depend on struct device */
 #include <linux/pm_wakeup.h>
 
 static inline const char *dev_name(const struct device *dev)
 {
         /* Use the init name until the kobject becomes available */
         if (dev->init_name)
                 return dev->init_name;
 
         return kobject_name(&dev->kobj);
 }
 
 extern __printf(2, 3)
 int dev_set_name(struct device *dev, const char *name, ...);
 
 #ifdef CONFIG_NUMA
 static inline int dev_to_node(struct device *dev)
 {
         return dev->numa_node;
 }
 static inline void set_dev_node(struct device *dev, int node)
 {
         dev->numa_node = node;
 }
 #else
 static inline int dev_to_node(struct device *dev)
 {
         return -1;
 }
 static inline void set_dev_node(struct device *dev, int node)
 {
 }
 #endif
 
 static inline void *dev_get_drvdata(const struct device *dev)
 {
         return dev->driver_data;
 }
 
 static inline void dev_set_drvdata(struct device *dev, void *data)
 {
         dev->driver_data = data;
 }
 
 static inline struct pm_subsys_data *dev_to_psd(struct device *dev)
 {
         return dev ? dev->power.subsys_data : NULL;
 }
 
 static inline unsigned int dev_get_uevent_suppress(const struct device *dev)
 {
         return dev->kobj.uevent_suppress;
 }
 
 static inline void dev_set_uevent_suppress(struct device *dev, int val)
 {
         dev->kobj.uevent_suppress = val;
 }
 
 static inline int device_is_registered(struct device *dev)
 {
         return dev->kobj.state_in_sysfs;
 }
 
 static inline void device_enable_async_suspend(struct device *dev)