u-boot/arch/x86/include/asm/early_cmos.h
Bin Meng 9f1fad1e36 x86: Add an early CMOS access library
This adds a library that provides CMOS (inside RTC SRAM) access
at a very early stage when driver model is not available yet.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Stefan Roese <sr@denx.de>
2017-05-17 17:11:46 +08:00

43 lines
1,009 B
C

/*
* Copyright (C) 2017, Bin Meng <bmeng.cn@gmail.com>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#ifndef __EARLY_CMOS_H
#define __EARLY_CMOS_H
/* CMOS actually resides in the RTC SRAM */
#define CMOS_IO_PORT 0x70
/**
* cmos_read8() - Get 8-bit data stored at the given address
*
* This reads from CMOS for the 8-bit data stored at the given address.
*
* @addr: RTC SRAM address
* @return: 8-bit data stored at the given address
*/
u8 cmos_read8(u8 addr);
/**
* cmos_read16() - Get 16-bit data stored at the given address
*
* This reads from CMOS for the 16-bit data stored at the given address.
*
* @addr: RTC SRAM address
* @return: 16-bit data stored at the given address
*/
u16 cmos_read16(u8 addr);
/**
* cmos_read32() - Get 32-bit data stored at the given address
*
* This reads from CMOS for the 32-bit data stored at the given address.
*
* @addr: RTC SRAM address
* @return: 32-bit data stored at the given address
*/
u32 cmos_read32(u8 addr);
#endif /* __EARLY_CMOS_H */