linux/include/linux/nvram.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_NVRAM_H
#define _LINUX_NVRAM_H

#include <linux/errno.h>
#include <uapi/linux/nvram.h>

#ifdef CONFIG_PPC
#include <asm/machdep.h>
#endif

/**
 * struct nvram_ops - NVRAM functionality made available to drivers
 * @read: validate checksum (if any) then load a range of bytes from NVRAM
 * @write: store a range of bytes to NVRAM then update checksum (if any)
 * @read_byte: load a single byte from NVRAM
 * @write_byte: store a single byte to NVRAM
 * @get_size: return the fixed number of bytes in the NVRAM
 *
 * Architectures which provide an nvram ops struct need not implement all
 * of these methods. If the NVRAM hardware can be accessed only one byte
 * at a time then it may be sufficient to provide .read_byte and .write_byte.
 * If the NVRAM has a checksum (and it is to be checked) the .read and
 * .write methods can be used to implement that efficiently.
 *
 * Portable drivers may use the wrapper functions defined here.
 * The nvram_read() and nvram_write() functions call the .read and .write
 * methods when available and fall back on the .read_byte and .write_byte
 * methods otherwise.
 */

struct nvram_ops { … };

extern const struct nvram_ops arch_nvram_ops;

static inline ssize_t nvram_get_size(void)
{ … }

static inline unsigned char nvram_read_byte(int addr)
{ … }

static inline void nvram_write_byte(unsigned char val, int addr)
{ … }

static inline ssize_t nvram_read_bytes(char *buf, size_t count, loff_t *ppos)
{ … }

static inline ssize_t nvram_write_bytes(char *buf, size_t count, loff_t *ppos)
{ … }

static inline ssize_t nvram_read(char *buf, size_t count, loff_t *ppos)
{ … }

static inline ssize_t nvram_write(char *buf, size_t count, loff_t *ppos)
{ … }

#endif  /* _LINUX_NVRAM_H */