ddr: altera: Add DDR driver for Agilex5 series

Adding DDR driver support for Agilex5 series.

Signed-off-by: Tingting Meng <tingting.meng@altera.com>
diff --git a/arch/arm/dts/socfpga_agilex5_socdk-u-boot.dtsi b/arch/arm/dts/socfpga_agilex5_socdk-u-boot.dtsi
index 540b266..e08dd55 100644
--- a/arch/arm/dts/socfpga_agilex5_socdk-u-boot.dtsi
+++ b/arch/arm/dts/socfpga_agilex5_socdk-u-boot.dtsi
@@ -22,11 +22,38 @@
 		};
 	};
 
-	memory {
-		/* 8GB */
-		reg = <0 0x80000000 0 0x80000000>,
-		      <8 0x80000000 1 0x80000000>;
-	};
+	/*
+	 * Both Memory base address and size default info is retrieved from HW setting.
+	 * Reconfiguration / Overwrite these info can be done with examples below.
+	 */
+	/*
+	 * Example for memory size with 2GB:
+	 * memory {
+	 *	reg = <0x0 0x80000000 0x0 0x80000000>;
+	 * };
+	 */
+	/*
+	 * Example for memory size with 8GB:
+	 * memory {
+	 *	reg = <0x0 0x80000000 0x0 0x80000000>,
+	 *	      <0x8 0x80000000 0x1 0x80000000>;
+	 * };
+	 */
+	/*
+	 * Example for memory size with 32GB:
+	 * memory {
+	 *	reg = <0x0 0x80000000 0x0 0x80000000>,
+	 *	      <0x8 0x80000000 0x7 0x80000000>;
+	 * };
+	 */
+	/*
+	 * Example for memory size with 512GB:
+	 * memory {
+	 *	reg = <0x0 0x80000000 0x0 0x80000000>,
+	 *	      <0x8 0x80000000 0x7 0x80000000>,
+	 *	      <0x88 0x00000000 0x78 0x00000000>;
+	 * };
+	 */
 
 	chosen {
 		stdout-path = "serial0:115200n8";