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     ┬дц└║uобаю ?В     /* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Pointer abstraction for IO/system memory
 */

#ifndef __IOSYS_MAP_H__
#define __IOSYS_MAP_H__

#include <linux/compiler_types.h>
#include <linux/io.h>
#include <linux/string.h>

/**
 * DOC: overview
 *
 * When accessing a memory region, depending on its location, users may have to
 * access it with I/O operations or memory load/store operations. For example,
 * copying to system memory could be done with memcpy(), copying to I/O memory
 * would be done with memcpy_toio().
 *
 * .. code-block:: c
 *
 *	void *vaddr = ...; // pointer to system memory
 *	memcpy(vaddr, src, len);
 *
 *	void *vaddr_iomem = ...; // pointer to I/O memory
 *	memcpy_toio(vaddr_iomem, src, len);
 *
 * The user of such pointer may not have information about the mapping of that
 * region or may want to have a single code path to handle operations on that
 * buffer, regardless if it's located in system or IO memory. The type
 * :c:type:`struct iosys_map <iosys_map>` and its helpers abstract that so the
 * buffer can be passed around to other drivers or have separate duties inside
 * the same driver for allocation, read and write operations.
 *
 * Open-coding access to :c:type:`struct iosys_map <iosys_map>` is considered
 * bad style. Rather then accessing its fields directly, use one of the provided
 * helper functions, or implement your own. For example, instances of
 * :c:type:`struct iosys_map <iosys_map>` can be initialized statically with
 * IOSYS_MAP_INIT_VADDR(), or at runtime with iosys_map_set_vaddr(). These
 * helpers will set an address in system memory.
 *
 * .. code-block:: c
 *
 *	struct iosys_map map = IOSYS_MAP_INIT_VADDR(0xdeadbeaf);
 *
 *	iosys_map_set_vaddr(&map, 0xdeadbeaf);
 *
 * To set an address in I/O memory, use IOSYS_MAP_INIT_VADDR_IOMEM() or
 * iosys_map_set_vaddr_iomem().
 *
 * .. code-block:: c
 *
 *	struct iosys_map map = IOSYS_MAP_INIT_VADDR_IOMEM(0xdeadbeaf);
 *
 *	iosys_map_set_vaddr_iomem(&map, 0xdeadbeaf);
 *
 * Instances of struct iosys_map do not have to be cleaned up, but
 * can be cleared to NULL with iosys_map_clear(). Cleared mappings
 * always refer to system memory.
 *
 * .. code-block:: c
 *
 *	iosys_map_clear(&map);
 *
 * Test if a mapping is valid with either iosys_map_is_set() or
 * iosys_map_is_null().
 *
 * .. code-block:: c
 *
 *	if (iosys_map_is_set(&map) != iosys_map_is_null(&map))
 *		// always true
 *
 * Instances of :c:type:`struct iosys_map <iosys_map>` can be compared for
 * equality with iosys_map_is_equal(). Mappings that point to different memory
 * spaces, system or I/O, are never equal. That's even true if both spaces are
 * located in the same address space, both mappings contain the same address
 * value, or both mappings refer to NULL.
 *
 * .. code-block:: c
 *
 *	struct iosys_map sys_map; // refers to system memory
 *	struct iosys_map io_map; // refers to I/O memory
 *
 *	if (iosys_map_is_equal(&sys_map, &io_map))
 *		// always false
 *
 * A set up instance of struct iosys_map can be used to access or manipulate the
 * buffer memory. Depending on the location of the memory, the provided helpers
 * will pick the correct operations. Data can be copied into the memory with
 * iosys_map_memcpy_to(). The address can be manipulated with iosys_map_incr().
 *
 * .. code-block:: c
 *
 *	const void *src = ...; // source buffer
 *	size_t len = ...; // length of src
 *
 *	iosys_map_memcpy_to(&map, src, len);
 *	iosys_map_incr(&map, len); // go to first byte after the memcpy
 */

/**
 * struct iosys_map - Pointer to IO/system memory
 * @vaddr_iomem:	The buffer's address if in I/O memory
 * @vaddr:		The buffer's address if in system memory
 * @is_iomem:		True if the buffer is located in I/O memory, or false
 *			otherwise.
 */
struct iosys_map {
	union {
		void __iomem *vaddr_iomem;
		void *vaddr;
	};
	bool is_iomem;
};

/**
 * IOSYS_MAP_INIT_VADDR - Initializes struct iosys_map to an address in system memory
 * @vaddr_:	A system