ARM: dts: sun9i: Add secure SRAM node used for SMP hotplug

The A80 stores some magic flags in a portion of the secure SRAM. The
BROM jumps directly to the software entry point set by the SMP code
if the flags are set. This is required for CPU0 hotplugging.
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>

arch/arm/boot/dts/sun9i-a80.dtsi

@@ -250,6 +250,25 @@ soc {
 		 */
 		ranges = <0 0 0 0x20000000>;
 
+		sram_b: sram@20000 {
+			/* 256 KiB secure SRAM at 0x20000 */
+			compatible = "mmio-sram";
+			reg = <0x00020000 0x40000>;
+
+			#address-cells = <1>;
+			#size-cells = <1>;
+			ranges = <0 0x00020000 0x40000>;
+
+			smp-sram@1000 {
+				/*
+				 * This is checked by BROM to determine if
+				 * cpu0 should jump to SMP entry vector
+				 */
+				compatible = "allwinner,sun9i-a80-smp-sram";
+				reg = <0x1000 0x8>;
+			};
+		};
+
 		ehci0: usb@a00000 {
 			compatible = "allwinner,sun9i-a80-ehci", "generic-ehci";
 			reg = <0x00a00000 0x100>;