dm: sf: Add tests for SPI flash

Add a simple test for SPI that uses SPI flash. It operates by creating a
SPI flash file and using the 'sf test' command to test that all
operations work correctly.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>
diff --git a/test/dm/test.dts b/test/dm/test.dts
index 8489595..1fba792 100644
--- a/test/dm/test.dts
+++ b/test/dm/test.dts
@@ -81,7 +81,7 @@
 		compatible = "google,another-fdt-test";
 	};
 
-	base-gpios {
+	gpio_a: base-gpios {
 		compatible = "sandbox,gpio";
 		gpio-bank-name = "a";
 		num-gpios = <20>;
@@ -92,4 +92,19 @@
 		gpio-bank-name = "b";
 		num-gpios = <10>;
 	};
+
+	spi@0 {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		reg = <0>;
+		compatible = "sandbox,spi";
+		cs-gpios = <0>, <&gpio_a 0>;
+		spi.bin@0 {
+			reg = <0>;
+			compatible = "spansion,m25p16", "spi-flash";
+			spi-max-frequency = <40000000>;
+			sandbox,filename = "spi.bin";
+		};
+	};
+
 };