include/linux/device.h

// SPDX-License-Identifier: GPL-2.0
/*
 * 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.
 *
 * See Documentation/driver-api/driver-model/ for more information.
 */

#ifndef _DEVICE_H_
#define _DEVICE_H_

#include <linux/dev_printk.h>
#include <linux/energy_model.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/pm.h>
#include <linux/atomic.h>
#include <linux/uidgid.h>
#include <linux/gfp.h>
#include <linux/overflow.h>
#include <linux/device/bus.h>
#include <linux/device/class.h>
#include <linux/device/driver.h>
#include <linux/cleanup.h>
#include <asm/device.h>

struct device;
struct device_private;
struct device_driver;
struct driver_private;
struct module;
struct class;
struct subsys_private;
struct device_node;
struct fwnode_handle;
struct iommu_group;
struct dev_pin_info;
struct dev_iommu;
struct msi_device_data;

/**
 * struct subsys_interface - interfaces to device functions
 * @name:       name of the device function
 * @subsys:     subsystem 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;
	const struct bus_type *subsys;
	struct list_head node;
	int (*add_dev)(struct device *dev, struct subsys_interface *sif);
	void (*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(const struct bus_type *subsys,
			   const struct attribute_group **groups);
int subsys_virtual_register(const struct bus_type *subsys,
			    const struct attribute_group **groups);

/*
 * 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 {
	const char *name;
	const struct attribute_group **groups;
	int (*uevent)(const struct device *dev, struct kobj_uevent_env *env);
	char *(*devnode)(const struct device *dev, umode_t *mode,
			 kuid_t *uid, kgid_t *gid);
	void (*release)(struct device *dev);

	const struct dev_pm_ops *pm;
};

/**
 * struct device_attribute - Interface for exporting device attributes.
 * @attr: sysfs attribute definition.
 * @show: Show handler.
 * @store: Store handler.
 */
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 - Exported device attribute with extra context.
 * @attr: Exported device attribute.
 * @var: Pointer to context.
 */
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);

/**
 * DEVICE_ATTR - Define a device attribute.
 * @_name: Attribute name.
 * @_mode: File mode.
 * @_show: Show handler. Optional, but mandatory if attribute is readable.
 * @_store: Store handler. Optional, but mandatory if attribute is writable.
 *
 * Convenience macro for defining a struct device_attribute.
 *
 * For example, ``DEVICE_ATTR(foo, 0644, foo_show, foo_store);`` expands to:
 *
 * .. code-block:: c
 *
 *	struct device_attribute dev_attr_foo = {
 *		.attr	= { .name = "foo", .mode = 0644 },
 *		.show	= foo_show,
 *		.store	= foo_store,
 *	};
 */
#define DEVICE_ATTR(_name, _mode, _show, _store) \
	struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store)

/**
 * DEVICE_ATTR_PREALLOC - Define a preallocated device attribute.
 * @_name: Attribute name.
 * @_mode: File mode.
 * @_show: Show handler. Optional, but mandatory if attribute is readable.
 * @_store: Store handler. Optional, but mandatory if attribute is writable.
 *
 * Like DEVICE_ATTR(), but ``SYSFS_PREALLOC`` is set on @_mode.
 */
#define DEVICE_ATTR_PREALLOC(_name, _mode, _show, _store) \
	struct device_attribute dev_attr_##_name = \
		__ATTR_PREALLOC(_name, _mode, _show, _store)

/**
 * DEVICE_ATTR_RW - Define a read-write device attribute.
 * @_name: Attribute name.
 *
 * Like DEVICE_ATTR(), but @_mode is 0644, @_show is <_name>_show,
 * and @_store is <_name>_store.
 */
#define DEVICE_ATTR_RW(_name) \
	struct device_attribute dev_attr_##_name = __ATTR_RW(_name)

/**
 * DEVICE_ATTR_ADMIN_RW - Define an admin-only read-write device attribute.
 * @_name: Attribute name.
 *
 * Like DEVICE_ATTR_RW(), but @_mode is 0600.
 */
#define DEVICE_ATTR_ADMIN_RW(_name) \
	struct device_attribute dev_attr_##_name = __ATTR_RW_MODE(_name, 0600)

/**
 * DEVICE_ATTR_RO - Define a readable device attribute.
 * @_name: Attribute name.
 *
 * Like DEVICE_ATTR(), but @_mode is 0444 and @_show is <_name>_show.
 */
#define DEVICE_ATTR_RO(_name) \
	struct device_attribute dev_attr_##_name = __ATTR_RO(_name)

/**
 * DEVICE_ATTR_ADMIN_RO - Define an admin-only readable device attribute.
 * @_name: Attribute name.
 *
 * Like DEVICE_ATTR_RO(), but @_mode is 0400.
 */
#define DEVICE_ATTR_ADMIN_RO(_name) \
	struct device_attribute dev_attr_##_name = __ATTR_RO_MODE(_name, 0400)

/**
 * DEVICE_ATTR_WO - Define an admin-only writable device attribute.
 * @_name: Attribute name.
 *
 * Like DEVICE_ATTR(), but @_mode is 0200 and @_store is <_name>_store.
 */
#define DEVICE_ATTR_WO(_name) \
	struct device_attribute dev_attr_##_name = __ATTR_WO(_name)

/**
 * DEVICE_ULONG_ATTR - Define a device attribute backed by an unsigned long.
 * @_name: Attribute name.
 * @_mode: File mode.
 * @_var: Identifier of unsigned long.
 *
 * Like DEVICE_ATTR(), but @_show and @_store are automatically provided
 * such that reads and writes to the attribute from userspace affect @_var.
 */
#define DEVICE_ULONG_ATTR(_name, _mode, _var) \
	struct dev_ext_attribute dev_attr_##_name = \
		{ __ATTR(_name, _mode, device_show_ulong, device_store_ulong), &(_var) }

/**
 * DEVICE_INT_ATTR - Define a device attribute backed by an int.
 * @_name: Attribute name.
 * @_mode: File mode.
 * @_var: Identifier of int.
 *
 * Like DEVICE_ULONG_ATTR(), but @_var is an int.
 */
#define DEVICE_INT_ATTR(_name, _mode, _var) \
	struct dev_ext_attribute dev_attr_##_name = \
		{ __ATTR(_name, _mode, device_show_int, device_store_int), &(_var) }

/**
 * DEVICE_BOOL_ATTR - Define a device attribute backed by a bool.
 * @_name: Attribute name.
 * @_mode: File mode.
 * @_var: Identifier of bool.
 *
 * Like DEVICE_ULONG_ATTR(), but @_var is a bool.
 */
#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)

int device_create_file(struct device *device,
		       const struct device_attribute *entry);
void device_remove_file(struct device *dev,
			const struct device_attribute *attr);
bool device_remove_file_self(struct device *dev,
			     const struct device_attribute *attr);
int __must_check device_create_bin_file(struct device *dev,
					const struct bin_attribute *attr);
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);

void *__devres_alloc_node(dr_release_t release, size_t size, gfp_t gfp,
			  int nid, const char *name) __malloc;
#define devres_alloc(release, size, gfp) \
	__devres_alloc_node(release, size, gfp, NUMA_NO_NODE, #release)
#define devres_alloc_node(release, size, gfp, nid) \
	__devres_alloc_node(release, size, gfp, nid, #release)

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);
void devres_free(void *res);
void devres_add(struct device *dev, void *res);
void *devres_find(struct device *dev, dr_release_t release,
		  dr_match_t match, void *match_data);
void *devres_get(struct device *dev, void *new_res,
		 dr_match_t match, void *match_data);
void *devres_remove(struct device *dev, dr_release_t release,
		    dr_match_t match, void *match_data);
int devres_destroy(struct device *dev, dr_release_t release,
		   dr_match_t match, void *match_data);
int devres_release(struct device *dev, dr_release_t release,
		   dr_match_t match, void *match_data);

/* devres group */
void * __must_check devres_open_group(struct device *dev, void *id, gfp_t gfp);
void devres_close_group(struct device *dev, void *id);
void devres_remove_group(struct device *dev, void *id);
int devres_release_group(struct device *dev, void *id);

/* managed devm_k.alloc/kfree for device drivers */
void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) __alloc_size(2);
void *devm_krealloc(struct device *dev, void *ptr, size_t size,
		    gfp_t gfp) __must_check __realloc_size(3);
__printf(3, 0) char *devm_kvasprintf(struct device *dev, gfp_t gfp,
				     const char *fmt, va_list ap) __malloc;
__printf(3, 4) char *devm_kasprintf(struct device *dev, gfp_t gfp,
				    const char *fmt, ...) __malloc;
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)
{
	size_t bytes;

	if (unlikely(check_mul_overflow(n, size, &bytes)))
		return NULL;

	return devm_kmalloc(dev, bytes, 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);
}
static inline __realloc_size(3, 4) void * __must_check
devm_krealloc_array(struct device *dev, void *p, size_t new_n, size_t new_size, gfp_t flags)
{
	size_t bytes;

	if (unlikely(check_mul_overflow(new_n, new_size, &bytes)))
		return NULL;

	return devm_krealloc(dev, p, bytes, flags);
}

void devm_kfree(struct device *dev, const void *p);
char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp) __malloc;
const char *devm_kstrdup_const(struct device *dev, const char *s, gfp_t gfp);
void *devm_kmemdup(struct device *dev, const void *src, size_t len, gfp_t gfp)
	__realloc_size(3);

unsigned long devm_get_free_pages(struct device *dev,
				  gfp_t gfp_mask, unsigned int order);
void devm_free_pages(struct device *dev, unsigned long addr);

#ifdef CONFIG_HAS_IOMEM
void __iomem *devm_ioremap_resource(struct device *dev,
				    const struct resource *res);
void __iomem *devm_ioremap_resource_wc(struct device *dev,
				       const struct resource *res);

void __iomem *devm_of_iomap(struct device *dev,
			    struct device_node *node, int index,
			    resource_size_t *size);
#else

static inline
void __iomem *devm_ioremap_resource(struct device *dev,
				    const struct resource *res)
{
	return ERR_PTR(-EINVAL);
}

static inline
void __iomem *devm_ioremap_resource_wc(struct device *dev,
				       const struct resource *res)
{
	return ERR_PTR(-EINVAL);
}

static inline
void __iomem *devm_of_iomap(struct device *dev,
			    struct device_node *node, int index,
			    resource_size_t *size)
{
	return ERR_PTR(-EINVAL);
}

#endif

/* allows to add/remove a custom action to devres stack */
void devm_remove_action(struct device *dev, void (*action)(void *), void *data);
void devm_release_action(struct device *dev, void (*action)(void *), void *data);

int __devm_add_action(struct device *dev, void (*action)(void *), void *data, const char *name);
#define devm_add_action(dev, action, data) \
	__devm_add_action(dev, action, data, #action)

static inline int __devm_add_action_or_reset(struct device *dev, void (*action)(void *),
					     void *data, const char *name)
{
	int ret;

	ret = __devm_add_action(dev, action, data, name);
	if (ret)
		action(data);

	return ret;
}
#define devm_add_action_or_reset(dev, action, data) \
	__devm_add_action_or_reset(dev, action, data, #action)

/**
 * devm_alloc_percpu - Resource-managed alloc_percpu
 * @dev: Device to allocate per-cpu memory for
 * @type: Type to allocate per-cpu memory for
 *
 * Managed alloc_percpu. Per-cpu memory allocated with this function is
 * automatically freed on driver detach.
 *
 * RETURNS:
 * Pointer to allocated memory on success, NULL on failure.
 */
#define devm_alloc_percpu(dev, type)      \
	((typeof(type) __percpu *)__devm_alloc_percpu((dev), sizeof(type), \
						      __alignof__(type)))

void __percpu *__devm_alloc_percpu(struct device *dev, size_t size,
				   size_t align);
void devm_free_percpu(struct device *dev, void __percpu *pdata);

struct device_dma_parameters {
	/*
	 * a low level driver may set these to teach IOMMU code about
	 * sg limitations.
	 */
	unsigned int max_segment_size;
	unsigned int min_align_mask;
	unsigned long segment_boundary_mask;
};

/**
 * enum device_link_state - Device link states.
 * @DL_STATE_NONE: The presence of the drivers is not being tracked.
 * @DL_STATE_DORMANT: None of the supplier/consumer drivers is present.
 * @DL_STATE_AVAILABLE: The supplier driver is present, but the consumer is not.
 * @DL_STATE_CONSUMER_PROBE: The consumer is probing (supplier driver present).
 * @DL_STATE_ACTIVE: Both the supplier and consumer drivers are present.
 * @DL_STATE_SUPPLIER_UNBIND: The supplier driver is unbinding.
 */
enum device_link_state {
	DL_STATE_NONE = -1,
	DL_STATE_DORMANT = 0,
	DL_STATE_AVAILABLE,
	DL_STATE_CONSUMER_PROBE,
	DL_STATE_ACTIVE,
	DL_STATE_SUPPLIER_UNBIND,
};

/*
 * Device link flags.
 *
 * STATELESS: The core will not remove this link automatically.
 * AUTOREMOVE_CONSUMER: Remove the link automatically on consumer driver unbind.
 * PM_RUNTIME: If set, the runtime PM framework will use this link.
 * RPM_ACTIVE: Run pm_runtime_get_sync() on the supplier during link creation.
 * AUTOREMOVE_SUPPLIER: Remove the link automatically on supplier driver unbind.
 * AUTOPROBE_CONSUMER: Probe consumer driver automatically after supplier binds.
 * MANAGED: The core tracks presence of supplier/consumer drivers (internal).
 * SYNC_STATE_ONLY: Link only affects sync_state() behavior.
 * INFERRED: Inferred from data (eg: firmware) and not from driver actions.
 */
#define DL_FLAG_STATELESS		BIT(0)
#define DL_FLAG_AUTOREMOVE_CONSUMER	BIT(1)
#define DL_FLAG_PM_RUNTIME		BIT(2)
#define DL_FLAG_RPM_ACTIVE		BIT(3)
#define DL_FLAG_AUTOREMOVE_SUPPLIER	BIT(4)
#define DL_FLAG_AUTOPROBE_CONSUMER	BIT(5)
#define DL_FLAG_MANAGED			BIT(6)
#define DL_FLAG_SYNC_STATE_ONLY		BIT(7)
#define DL_FLAG_INFERRED		BIT(8)
#define DL_FLAG_CYCLE			BIT(9)

/**
 * enum dl_dev_state - Device driver presence tracking information.
 * @DL_DEV_NO_DRIVER: There is no driver attached to the device.
 * @DL_DEV_PROBING: A driver is probing.
 * @DL_DEV_DRIVER_BOUND: The driver has been bound to the device.
 * @DL_DEV_UNBINDING: The driver is unbinding from the device.
 */
enum dl_dev_state {
	DL_DEV_NO_DRIVER = 0,
	DL_DEV_PROBING,
	DL_DEV_DRIVER_BOUND,
	DL_DEV_UNBINDING,
};

/**
 * enum device_removable - Whether the device is removable. The criteria for a
 * device to be classified as removable is determined by its subsystem or bus.
 * @DEVICE_REMOVABLE_NOT_SUPPORTED: This attribute is not supported for this
 *				    device (default).
 * @DEVICE_REMOVABLE_UNKNOWN:  Device location is Unknown.
 * @DEVICE_FIXED: Device is not removable by the user.
 * @DEVICE_REMOVABLE: Device is removable by the user.
 */
enum device_removable {
	DEVICE_REMOVABLE_NOT_SUPPORTED = 0, /* must be 0 */
	DEVICE_REMOVABLE_UNKNOWN,
	DEVICE_FIXED,
	DEVICE_REMOVABLE,
};

/**
 * struct dev_links_info - Device data related to device links.
 * @suppliers: List of links to supplier devices.
 * @consumers: List of links to consumer devices.
 * @defer_sync: Hook to global list of devices that have deferred sync_state.
 * @status: Driver status information.
 */
struct dev_links_info {
	struct list_head suppliers;
	struct list_head consumers;
	struct list_head defer_sync;
	enum dl_dev_state status;
};

/**
 * struct dev_msi_info - Device data related to MSI
 * @domain:	The MSI interrupt domain associated to the device
 * @data:	Pointer to MSI device data
 */
struct dev_msi_info {
#ifdef CONFIG_GENERIC_MSI_IRQ
	struct irq_domain	*domain;
	struct msi_device_data	*data;
#endif
};

/**
 * enum device_physical_location_panel - Describes which panel surface of the
 * system's housing the device connection point resides on.
 * @DEVICE_PANEL_TOP: Device connection point is on the top panel.
 * @DEVICE_PANEL_BOTTOM: Device connection point is on the bottom panel.
 * @DEVICE_PANEL_LEFT: Device connection point is on the left panel.
 * @DEVICE_PANEL_RIGHT: Device connection point is on the right panel.
 * @DEVICE_PANEL_FRONT: Device connection point is on the front panel.
 * @DEVICE_PANEL_BACK: Device connection point is on the back panel.
 * @DEVICE_PANEL_UNKNOWN: The panel with device connection point is unknown.
 */
enum device_physical_location_panel {
	DEVICE_PANEL_TOP,
	DEVICE_PANEL_BOTTOM,
	DEVICE_PANEL_LEFT,
	DEVICE_PANEL_RIGHT,
	DEVICE_PANEL_FRONT,
	DEVICE_PANEL_BACK,
	DEVICE_PANEL_UNKNOWN,
};

/**
 * enum device_physical_location_vertical_position - Describes vertical
 * position of the device connection point on the panel surface.
 * @DEVICE_VERT_POS_UPPER: Device connection point is at upper part of panel.
 * @DEVICE_VERT_POS_CENTER: Device connection point is at center part of panel.
 * @DEVICE_VERT_POS_LOWER: Device connection point is at lower part of panel.
 */
enum device_physical_location_vertical_position {
	DEVICE_VERT_POS_UPPER,
	DEVICE_VERT_POS_CENTER,
	DEVICE_VERT_POS_LOWER,
};

/**
 * enum device_physical_location_horizontal_position - Describes horizontal
 * position of the device connection point on the panel surface.
 * @DEVICE_HORI_POS_LEFT: Device connection point is at left part of panel.
 * @DEVICE_HORI_POS_CENTER: Device connection point is at center part of panel.
 * @DEVICE_HORI_POS_RIGHT: Device connection point is at right part of panel.
 */
enum device_physical_location_horizontal_position {
	DEVICE_HORI_POS_LEFT,
	DEVICE_HORI_POS_CENTER,
	DEVICE_HORI_POS_RIGHT,
};

/**
 * struct device_physical_location - Device data related to physical location
 * of the device connection point.
 * @panel: Panel surface of the system's housing that the device connection
 *         point resides on.
 * @vertical_position: Vertical position of the device connection point within
 *                     the panel.
 * @horizontal_position: Horizontal position of the device connection point
 *                       within the panel.
 * @dock: Set if the device connection point resides in a docking station or
 *        port replicator.
 * @lid: Set if this device connection point resides on the lid of laptop
 *       system.
 */
struct device_physical_location {
	enum device_physical_location_panel panel;
	enum device_physical_location_vertical_position vertical_position;
	enum device_physical_location_horizontal_position horizontal_position;
	bool dock;
	bool lid;
};

/**
 * 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.
 * @links:	Links to suppliers and consumers of this device.
 * @power:	For device power management.
 *		See Documentation/driver-api/pm/devices.rst 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.
 * @em_pd:	device's energy model performance domain
 * @pins:	For device pin management.
 *		See Documentation/driver-api/pin-control.rst for details.
 * @msi:	MSI related data
 * @numa_node:	NUMA node this device is close to.
 * @dma_ops:    DMA mapping operations for this device.
 * @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.
 * @bus_dma_limit: Limit of an upstream bridge or bus which imposes a smaller
 *		DMA limit than the device itself supports.
 * @dma_range_map: map for DMA memory ranges relative to that 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
 * @dma_io_tlb_mem: Software IO TLB allocator.  Not for driver use.
 * @dma_io_tlb_pools:	List of transient swiotlb memory pools.
 * @dma_io_tlb_lock:	Protects changes to the list of active pools.
 * @dma_uses_io_tlb: %true if device has used the software IO TLB.
 * @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.
 * @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.
 * @iommu:	Per device generic IOMMU runtime data
 * @physical_location: Describes physical location of the device connection
 *		point in the system housing.
 * @removable:  Whether the device can be removed from the system. This
 *              should be set by the subsystem / bus driver that discovered
 *              the device.
 *
 * @offline_disabled: If set, the device is permanently online.
 * @offline:	Set after successful invocation of bus type's .offline().
 * @of_node_reused: Set if the device-tree node is shared with an ancestor
 *              device.
 * @state_synced: The hardware state of this device has been synced to match
 *		  the software state of this device by calling the driver/bus
 *		  sync_state() callback.
 * @can_match:	The device has matched with a driver at least once or it is in
 *		a bus (like AMBA) which can't check for matching drivers until
 *		other devices probe successfully.
 * @dma_coherent: this particular device is dma coherent, even if the
 *		architecture supports non-coherent devices.
 * @dma_ops_bypass: If set to %true then the dma_ops are bypassed for the
 *		streaming DMA operations (->map_* / ->unmap_* / ->sync_*),
 *		and optionall (if the coherent mask is large enough) also
 *		for dma allocations.  This flag is managed by the dma ops
 *		instance from ->dma_supported.
 *
 * 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.
 */
struct device {
	struct kobject kobj;
	struct device		*parent;

	struct device_private	*p;

	const char		*init_name; /* initial name of the device */
	const struct device_type *type;

	const struct bus_type	*bus;	/* type of bus device is on */
	struct device_driver *driver;	/* which driver has allocated this
					   device */
	void		*platform_data;	/* Platform specific data, device
					   core doesn't touch it */
	void		*driver_data;	/* Driver data, set and get with
					   dev_set_drvdata/dev_get_drvdata */
	struct mutex		mutex;	/* mutex to synchronize calls to
					 * its driver.
					 */

	struct dev_links_info	links;
	struct dev_pm_info	power;
	struct dev_pm_domain	*pm_domain;

#ifdef CONFIG_ENERGY_MODEL
	struct em_perf_domain	*em_pd;
#endif

#ifdef CONFIG_PINCTRL
	struct dev_pin_info	*pins;
#endif
	struct dev_msi_info	msi;
#ifdef CONFIG_DMA_OPS
	const struct dma_map_ops *dma_ops;
#endif
	u64		*dma_mask;	/* dma mask (if dma'able device) */
	u64		coherent_dma_mask;/* Like dma_mask, but for
					     alloc_coherent mappings as
					     not all hardware supports
					     64 bit addresses for consistent
					     allocations such descriptors. */
	u64		bus_dma_limit;	/* upstream dma constraint */
	const struct bus_dma_region *dma_range_map;

	struct device_dma_parameters *dma_parms;

	struct list_head	dma_pools;	/* dma pools (if dma'ble) */

#ifdef CONFIG_DMA_DECLARE_COHERENT
	struct dma_coherent_mem	*dma_mem; /* internal for coherent mem
					     override */
#endif
#ifdef CONFIG_DMA_CMA
	struct cma *cma_area;		/* contiguous memory area for dma
					   allocations */
#endif
#ifdef CONFIG_SWIOTLB
	struct io_tlb_mem *dma_io_tlb_mem;
#endif
#ifdef CONFIG_SWIOTLB_DYNAMIC
	struct list_head dma_io_tlb_pools;
	spinlock_t dma_io_tlb_lock;
	bool dma_uses_io_tlb;
#endif
	/* arch specific additions */
	struct dev_archdata	archdata;

	struct device_node	*of_node; /* associated device tree node */
	struct fwnode_handle	*fwnode; /* firmware device node */

#ifdef CONFIG_NUMA
	int		numa_node;	/* NUMA node this device is close to */
#endif
	dev_t			devt;	/* dev_t, creates the sysfs "dev" */
	u32			id;	/* device instance */

	spinlock_t		devres_lock;
	struct list_head	devres_head;

	const struct class	*class;
	const struct attribute_group **groups;	/* optional groups */

	void	(*release)(struct device *dev);
	struct iommu_group	*iommu_group;
	struct dev_iommu	*iommu;

	struct device_physical_location *physical_location;

	enum device_removable	removable;

	bool			offline_disabled:1;
	bool			offline:1;
	bool			of_node_reused:1;
	bool			state_synced:1;
	bool			can_match:1;
#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
    defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
    defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
	bool			dma_coherent:1;
#endif
#ifdef CONFIG_DMA_OPS_BYPASS
	bool			dma_ops_bypass : 1;
#endif
};

/**
 * struct device_link - Device link representation.
 * @supplier: The device on the supplier end of the link.
 * @s_node: Hook to the supplier device's list of links to consumers.
 * @consumer: The device on the consumer end of the link.
 * @c_node: Hook to the consumer device's list of links to suppliers.
 * @link_dev: device used to expose link details in sysfs
 * @status: The state of the link (with respect to the presence of drivers).
 * @flags: Link flags.
 * @rpm_active: Whether or not the consumer device is runtime-PM-active.
 * @kref: Count repeated addition of the same link.
 * @rm_work: Work structure used for removing the link.
 * @supplier_preactivated: Supplier has been made active before consumer probe.
 */
struct device_link {
	struct device *supplier;
	struct list_head s_node;
	struct device *consumer;
	struct list_head c_node;
	struct device link_dev;
	enum device_link_state status;
	u32 flags;
	refcount_t rpm_active;
	struct kref kref;
	struct work_struct rm_work;
	bool supplier_preactivated; /* Owned by consumer probe. */
};

#define kobj_to_dev(__kobj)	container_of_const(__kobj, struct device, kobj)

/**
 * device_iommu_mapped - Returns true when the device DMA is translated
 *			 by an IOMMU
 * @dev: Device to perform the check on
 */
static inline bool device_iommu_mapped(struct device *dev)
{
	return (dev->iommu_group != NULL);
}

/* Get the wakeup routines, which depend on struct device */
#include <linux/pm_wakeup.h>

/**
 * dev_name - Return a device's name.
 * @dev: Device with name to get.
 * Return: The kobject name of the device, or its initial name if unavailable.
 */
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);
}

/**
 * dev_bus_name - Return a device's bus/class name, if at all possible
 * @dev: struct device to get the bus/class name of
 *
 * Will return the name of the bus/class the device is attached to.  If it is
 * not attached to a bus/class, an empty string will be returned.
 */
static inline const char *dev_bus_name(const struct device *dev)
{
	return dev->bus ? dev->bus->name : (dev->class ? dev->class->name : "");
}

__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 NUMA_NO_NODE;
}
static inline void set_dev_node(struct device *dev, int node)
{
}
#endif

static inline struct irq_domain *dev_get_msi_domain(const struct device *dev)
{
#ifdef CONFIG_GENERIC_MSI_IRQ
	return dev->msi.domain;
#else
	return NULL;
#endif
}

static inline void dev_set_msi_domain(struct device *dev, struct irq_domain *d)
{
#ifdef CONFIG_GENERIC_MSI_IRQ
	dev->msi.domain = d;
#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)
{
	if (!dev->power.is_prepared)
		dev->power.async_suspend = true;
}

static inline void device_disable_async_suspend(struct device *dev)
{
	if (!dev->power.is_prepared)
		dev->power.async_suspend = false;
}

static inline bool device_async_suspend_enabled(struct device *dev)
{
	return !!dev->power.async_suspend;
}

static inline bool device_pm_not_required(struct device *dev)
{
	return dev->power.no_pm;
}

static inline void device_set_pm_not_required(struct device *dev)
{
	dev->power.no_pm = true;
}

static inline void dev_pm_syscore_device(struct device *dev, bool val)
{
#ifdef CONFIG_PM_SLEEP
	dev->power.syscore = val;
#endif
}

static inline void dev_pm_set_driver_flags(struct device *dev, u32 flags)
{
	dev->power.driver_flags = flags;
}

static inline bool dev_pm_test_driver_flags(struct device *dev, u32 flags)
{
	return !!(dev->power.driver_flags & flags);
}

static inline void device_lock(struct device *dev)
{
	mutex_lock(&dev->mutex);
}

static inline int device_lock_interruptible(struct device *dev)
{
	return mutex_lock_interruptible(&dev->mutex);
}

static inline int device_trylock(struct device *dev)
{
	return mutex_trylock(&dev->mutex);
}

static inline void device_unlock(struct device *dev)
{
	mutex_unlock(&dev->mutex);
}

DEFINE_GUARD(device, struct device *, device_lock(_T), device_unlock(_T))

static inline void device_lock_assert(struct device *dev)
{
	lockdep_assert_held(&dev->mutex);
}

static inline struct device_node *dev_of_node(struct device *dev)
{
	if (!IS_ENABLED(CONFIG_OF) || !dev)
		return NULL;
	return dev->of_node;
}

static inline bool dev_has_sync_state(struct device *dev)
{
	if (!dev)
		return false;
	if (dev->driver && dev->driver->sync_state)
		return true;
	if (dev->bus && dev->bus->sync_state)
		return true;
	return false;
}

static inline void dev_set_removable(struct device *dev,
				     enum device_removable removable)
{
	dev->removable = removable;
}

static inline bool dev_is_removable(struct device *dev)
{
	return dev->removable == DEVICE_REMOVABLE;
}

static inline bool dev_removable_is_valid(struct device *dev)
{
	return dev->removable != DEVICE_REMOVABLE_NOT_SUPPORTED;
}

/*
 * High level routines for use by the bus drivers
 */
int __must_check device_register(struct device *dev);
void device_unregister(struct device *dev);
void device_initialize(struct device *dev);
int __must_check device_add(struct device *dev);
void device_del(struct device *dev);

DEFINE_FREE(device_del, struct device *, if (_T) device_del(_T))

int device_for_each_child(struct device *dev, void *data,
			  int (*fn)(struct device *dev, void *data));
int device_for_each_child_reverse(struct device *dev, void *data,
				  int (*fn)(struct device *dev, void *data));
struct device *device_find_child(struct device *dev, void *data,
				 int (*match)(struct device *dev, void *data));
struct device *device_find_child_by_name(struct device *parent,
					 const char *name);
struct device *device_find_any_child(struct device *parent);

int device_rename(struct device *dev, const char *new_name);
int device_move(struct device *dev, struct device *new_parent,
		enum dpm_order dpm_order);
int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid);

static inline bool device_supports_offline(struct device *dev)
{
	return dev->bus && dev->bus->offline && dev->bus->online;
}

#define __device_lock_set_class(dev, name, key)                        \
do {                                                                   \
	struct device *__d2 __maybe_unused = dev;                      \
	lock_set_class(&__d2->mutex.dep_map, name, key, 0, _THIS_IP_); \
} while (0)

/**
 * device_lock_set_class - Specify a temporary lock class while a device
 *			   is attached to a driver
 * @dev: device to modify
 * @key: lock class key data
 *
 * This must be called with the device_lock() already held, for example
 * from driver ->probe(). Take care to only override the default
 * lockdep_no_validate class.
 */
#ifdef CONFIG_LOCKDEP
#define device_lock_set_class(dev, key)                                    \
do {                                                                       \
	struct device *__d = dev;                                          \
	dev_WARN_ONCE(__d, !lockdep_match_class(&__d->mutex,               \
						&__lockdep_no_validate__), \
		 "overriding existing custom lock class\n");               \
	__device_lock_set_class(__d, #key, key);                           \
} while (0)
#else
#define device_lock_set_class(dev, key) __device_lock_set_class(dev, #key, key)
#endif

/**
 * device_lock_reset_class - Return a device to the default lockdep novalidate state
 * @dev: device to modify
 *
 * This must be called with the device_lock() already held, for example
 * from driver ->remove().
 */
#define device_lock_reset_class(dev) \
do { \
	struct device *__d __maybe_unused = dev;                       \
	lock_set_novalidate_class(&__d->mutex.dep_map, "&dev->mutex",  \
				  _THIS_IP_);                          \
} while (0)

void lock_device_hotplug(void);
void unlock_device_hotplug(void);
int lock_device_hotplug_sysfs(void);
int device_offline(struct device *dev);
int device_online(struct device *dev);
void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode);
void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode);
void device_set_of_node_from_dev(struct device *dev, const struct device *dev2);
void device_set_node(struct device *dev, struct fwnode_handle *fwnode);

static inline int dev_num_vf(struct device *dev)
{
	if (dev->bus && dev->bus->num_vf)
		return dev->bus->num_vf(dev);
	return 0;
}

/*
 * Root device objects for grouping under /sys/devices
 */
struct device *__root_device_register(const char *name, struct module *owner);

/* This is a macro to avoid include problems with THIS_MODULE */
#define root_device_register(name) \
	__root_device_register(name, THIS_MODULE)

void root_device_unregister(struct device *root);

static inline void *dev_get_platdata(const struct device *dev)
{
	return dev->platform_data;
}

/*
 * Manual binding of a device to driver. See drivers/base/bus.c
 * for information on use.
 */
int __must_check device_driver_attach(struct device_driver *drv,
				      struct device *dev);
int __must_check device_bind_driver(struct device *dev);
void device_release_driver(struct device *dev);
int  __must_check device_attach(struct device *dev);
int __must_check driver_attach(struct device_driver *drv);
void device_initial_probe(struct device *dev);
int __must_check device_reprobe(struct device *dev);

bool device_is_bound(struct device *dev);

/*
 * Easy functions for dynamically creating devices on the fly
 */
__printf(5, 6) struct device *
device_create(const struct class *cls, struct device *parent, dev_t devt,
	      void *drvdata, const char *fmt, ...);
__printf(6, 7) struct device *
device_create_with_groups(const struct class *cls, struct device *parent, dev_t devt,
			  void *drvdata, const struct attribute_group **groups,
			  const char *fmt, ...);
void device_destroy(const struct class *cls, dev_t devt);

int __must_check device_add_groups(struct device *dev,
				   const struct attribute_group **groups);
void device_remove_groups(struct device *dev,
			  const struct attribute_group **groups);

static inline int __must_check device_add_group(struct device *dev,
					const struct attribute_group *grp)
{
	const struct attribute_group *groups[] = { grp, NULL };

	return device_add_groups(dev, groups);
}

static inline void device_remove_group(struct device *dev,
				       const struct attribute_group *grp)
{
	const struct attribute_group *groups[] = { grp, NULL };

	return device_remove_groups(dev, groups);
}

int __must_check devm_device_add_groups(struct device *dev,
					const struct attribute_group **groups);
int __must_check devm_device_add_group(struct device *dev,
				       const struct attribute_group *grp);

/*
 * Platform "fixup" functions - allow the platform to have their say
 * about devices and actions that the general device layer doesn't
 * know about.
 */
/* Notify platform of device discovery */
extern int (*platform_notify)(struct device *dev);

extern int (*platform_notify_remove)(struct device *dev);


/*
 * get_device - atomically increment the reference count for the device.
 *
 */
struct device *get_device(struct device *dev);
void put_device(struct device *dev);

DEFINE_FREE(put_device, struct device *, if (_T) put_device(_T))

bool kill_device(struct device *dev);

#ifdef CONFIG_DEVTMPFS
int devtmpfs_mount(void);
#else
static inline int devtmpfs_mount(void) { return 0; }
#endif

/* drivers/base/power/shutdown.c */
void device_shutdown(void);

/* debugging and troubleshooting/diagnostic helpers. */
const char *dev_driver_string(const struct device *dev);

/* Device links interface. */
struct device_link *device_link_add(struct device *consumer,
				    struct device *supplier, u32 flags);
void device_link_del(struct device_link *link);
void device_link_remove(void *consumer, struct device *supplier);
void device_links_supplier_sync_state_pause(void);
void device_links_supplier_sync_state_resume(void);

/* Create alias, so I can be autoloaded. */
#define MODULE_ALIAS_CHARDEV(major,minor) \
	MODULE_ALIAS("char-major-" __stringify(major) "-" __stringify(minor))
#define MODULE_ALIAS_CHARDEV_MAJOR(major) \
	MODULE_ALIAS("char-major-" __stringify(major) "-*")

#endif /* _DEVICE_H_ */