video_osd: Add osd sandbox driver and tests

Add sandbox driver and tests for the new OSD uclass.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: Simon Glass <sjg@chromium.org>

arch/sandbox/dts/test.dts

@@ -37,6 +37,7 @@
 		usb1 = &usb_1;
 		usb2 = &usb_2;
 		axi0 = &axi;
+		osd0 = "/osd";
 	};
 
 	a-test {
@@ -642,6 +643,10 @@
 			};
 		};
 	};
+
+	osd {
+		compatible = "sandbox,sandbox_osd";
+	};
 };
 
 #include "sandbox_pmic.dtsi"

arch/sandbox/include/asm/test.h

@@ -90,4 +90,12 @@ long sandbox_i2c_rtc_get_set_base_time(struct udevice *dev, long base_time);
 
 int sandbox_usb_keyb_add_string(struct udevice *dev, const char *str);
 
+/**
+ * sandbox_osd_get_mem() - get the internal memory of a sandbox OSD
+ *
+ * @dev:	OSD device for which to access the internal memory for
+ * @buf:	pointer to buffer to receive the OSD memory data
+ * @buflen:	length of buffer in bytes
+ */
+int sandbox_osd_get_mem(struct udevice *dev, u8 *buf, size_t buflen);
 #endif