1 files changed, 51 insertions, 0 deletions
diff --git a/arch/x86/lib/early_cmos.c b/arch/x86/lib/early_cmos.c
new file mode 100644
index 0000000000..fa0b3273a8
--- /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;
+}