ARM: dts: alt: Add QSPI device to DT

Enable the QSPI controller in the alt device tree.

Based similar work for the silk board by by Vladimir Barinov and
Sergei Shtylyov.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm/boot/dts/r8a7794-alt.dts

@@ -138,6 +138,13 @@ &cmt0 {
 	status = "okay";
 };
 
+&pfc {
+	qspi_pins: spi0 {
+		renesas,groups = "qspi_ctrl", "qspi_data4";
+		renesas,function = "qspi";
+	};
+};
+
 &ether {
 	pinctrl-0 = <&ether_pins &phy1_pins>;
 	pinctrl-names = "default";
@@ -197,3 +204,42 @@ &scif2 {
 
 	status = "okay";
 };
+
+&qspi {
+	pinctrl-0 = <&qspi_pins>;
+	pinctrl-names = "default";
+
+	status = "okay";
+
+	flash@0 {
+		compatible = "spansion,s25fl512s", "jedec,spi-nor";
+		reg = <0>;
+		spi-max-frequency = <30000000>;
+		spi-tx-bus-width = <4>;
+		spi-rx-bus-width = <4>;
+		spi-cpol;
+		spi-cpha;
+		m25p,fast-read;
+
+		partitions {
+			compatible = "fixed-partitions";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			partition@0 {
+				label = "loader";
+				reg = <0x00000000 0x00040000>;
+				read-only;
+			};
+			partition@40000 {
+				label = "system";
+				reg = <0x00040000 0x00040000>;
+				read-only;
+			};
+			partition@80000 {
+				label = "user";
+				reg = <0x00080000 0x03f80000>;
+			};
+		};
+	};
+};