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 ---
arch/x86/include/asm/early_cmos.h | 43 +++++++++++++++++++++++++++++++++ arch/x86/lib/Makefile | 1 + arch/x86/lib/early_cmos.c | 51 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 95 insertions(+) create mode 100644 arch/x86/include/asm/early_cmos.h create mode 100644 arch/x86/lib/early_cmos.c
diff --git a/arch/x86/include/asm/early_cmos.h b/arch/x86/include/asm/early_cmos.h new file mode 100644 index 0000000..cd2634d --- /dev/null +++ b/arch/x86/include/asm/early_cmos.h @@ -0,0 +1,43 @@ +/* + * 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 */ diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index c61f931..cd4e976 100644 --- a/arch/x86/lib/Makefile +++ b/arch/x86/lib/Makefile @@ -15,6 +15,7 @@ obj-$(CONFIG_CMD_BOOTM) += bootm.o endif obj-y += cmd_boot.o obj-$(CONFIG_SEABIOS) += coreboot_table.o +obj-y += early_cmos.o obj-$(CONFIG_EFI) += efi/ obj-y += e820.o obj-y += gcc.o diff --git a/arch/x86/lib/early_cmos.c b/arch/x86/lib/early_cmos.c new file mode 100644 index 0000000..fa0b327 --- /dev/null +++ b/arch/x86/lib/early_cmos.c @@ -0,0 +1,51 @@ +/* + * Copyright (C) 2017, Bin Meng bmeng.cn@gmail.com + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +/* + * This library provides CMOS (inside RTC SRAM) access routines at a very + * early stage when driver model is not available yet. Only read access is + * provided. The 16-bit/32-bit read are compatible with driver model RTC + * uclass write ops, that data is stored in little-endian mode. + */ + +#include <common.h> +#include <asm/early_cmos.h> +#include <asm/io.h> + +u8 cmos_read8(u8 addr) +{ + outb(addr, CMOS_IO_PORT); + + return inb(CMOS_IO_PORT + 1); +} + +u16 cmos_read16(u8 addr) +{ + u16 value = 0; + u16 data; + int i; + + for (i = 0; i < sizeof(value); i++) { + data = cmos_read8(addr + i); + value |= data << (i << 3); + } + + return value; +} + +u32 cmos_read32(u8 addr) +{ + u32 value = 0; + u32 data; + int i; + + for (i = 0; i < sizeof(value); i++) { + data = cmos_read8(addr + i); + value |= data << (i << 3); + } + + return value; +}