ram: rk3399: Map chipselect for lpddr4

Assign desired cs_map values for lpddr4 during set memory map.

Initial cs_map values is based on the sdram parameters, so
the same will adjusted based dramtype as LPDDR4.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: YouMin Chen <cym@rock-chips.com>
diff --git a/drivers/ram/rockchip/sdram_rk3399.c b/drivers/ram/rockchip/sdram_rk3399.c
index e526512..2498620 100644
--- a/drivers/ram/rockchip/sdram_rk3399.c
+++ b/drivers/ram/rockchip/sdram_rk3399.c
@@ -188,6 +188,16 @@
 	clrsetbits_le32(&denali_pi[155], (0x3 << 16) | (0x7 << 24),
 			((3 - sdram_ch->cap_info.bk) << 16) |
 			((16 - row) << 24));
+
+	if (IS_ENABLED(CONFIG_RAM_RK3399_LPDDR4)) {
+		if (cs_map == 1)
+			cs_map = 0x5;
+		else if (cs_map == 2)
+			cs_map = 0xa;
+		else
+			cs_map = 0xF;
+	}
+
 	/* PI_41 PI_CS_MAP:RW:24:4 */
 	clrsetbits_le32(&denali_pi[41], 0xf << 24, cs_map << 24);
 	if (sdram_ch->cap_info.rank == 1 && params->base.dramtype == DDR3)