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...@gmail.com>
Reviewed-by: Simon Glass <s...@chromium.org>
---
Changes in v2: None
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...@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 21f59a0..fe00d75 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...@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;
+}
--
2.9.2
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