diff --git a/arch/arm/mach-rockchip/sdram_common.c b/arch/arm/mach-rockchip/sdram_common.c
new file mode 100644
index 0000000..76dbdc8
--- /dev/null
+++ b/arch/arm/mach-rockchip/sdram_common.c
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2017 Rockchip Electronics Co., Ltd.
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <ram.h>
+#include <asm/io.h>
+#include <asm/arch/sdram_common.h>
+#include <dm/uclass-internal.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+size_t rockchip_sdram_size(phys_addr_t reg)
+{
+	u32 rank, col, bk, cs0_row, cs1_row, bw, row_3_4;
+	size_t chipsize_mb = 0;
+	size_t size_mb = 0;
+	u32 ch;
+
+	u32 sys_reg = readl(reg);
+	u32 ch_num = 1 + ((sys_reg >> SYS_REG_NUM_CH_SHIFT)
+		       & SYS_REG_NUM_CH_MASK);
+
+	debug("%s %x %x\n", __func__, (u32)reg, sys_reg);
+	for (ch = 0; ch < ch_num; ch++) {
+		rank = 1 + (sys_reg >> SYS_REG_RANK_SHIFT(ch) &
+			SYS_REG_RANK_MASK);
+		col = 9 + (sys_reg >> SYS_REG_COL_SHIFT(ch) & SYS_REG_COL_MASK);
+		bk = 3 - ((sys_reg >> SYS_REG_BK_SHIFT(ch)) & SYS_REG_BK_MASK);
+		cs0_row = 13 + (sys_reg >> SYS_REG_CS0_ROW_SHIFT(ch) &
+				SYS_REG_CS0_ROW_MASK);
+		cs1_row = 13 + (sys_reg >> SYS_REG_CS1_ROW_SHIFT(ch) &
+				SYS_REG_CS1_ROW_MASK);
+		bw = (2 >> ((sys_reg >> SYS_REG_BW_SHIFT(ch)) &
+			SYS_REG_BW_MASK));
+		row_3_4 = sys_reg >> SYS_REG_ROW_3_4_SHIFT(ch) &
+			SYS_REG_ROW_3_4_MASK;
+
+		chipsize_mb = (1 << (cs0_row + col + bk + bw - 20));
+
+		if (rank > 1)
+			chipsize_mb += chipsize_mb >> (cs0_row - cs1_row);
+		if (row_3_4)
+			chipsize_mb = chipsize_mb * 3 / 4;
+		size_mb += chipsize_mb;
+		debug("rank %d col %d bk %d cs0_row %d bw %d row_3_4 %d\n",
+		      rank, col, bk, cs0_row, bw, row_3_4);
+	}
+
+	return (size_t)size_mb << 20;
+}
+
+int dram_init(void)
+{
+	struct ram_info ram;
+	struct udevice *dev;
+	int ret;
+
+	ret = uclass_get_device(UCLASS_RAM, 0, &dev);
+	if (ret) {
+		debug("DRAM init failed: %d\n", ret);
+		return ret;
+	}
+	ret = ram_get_info(dev, &ram);
+	if (ret) {
+		debug("Cannot get DRAM size: %d\n", ret);
+		return ret;
+	}
+	gd->ram_size = ram.size;
+	debug("SDRAM base=%lx, size=%lx\n",
+	      (unsigned long)ram.base, (unsigned long)ram.size);
+
+	return 0;
+}
+
+ulong board_get_usable_ram_top(ulong total_size)
+{
+	unsigned long top = CONFIG_SYS_SDRAM_BASE + SDRAM_MAX_SIZE;
+
+	return (gd->ram_top > top) ? top : gd->ram_top;
+}