test: panel: Add a test for the panel uclass

At present this uclass has no tests. Add a simple one which checks the PWM
configuration, regulator and GPIO.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/dts/sandbox_pmic.dtsi

@@ -60,7 +60,7 @@
 		regulator-max-microvolt = <3300000>;
 	};
 
-	ldo1 {
+	ldo_1: ldo1 {
 		regulator-name = "VDD_EMMC_1.8V";
 		regulator-min-microvolt = <1800000>;
 		regulator-max-microvolt = <1800000>;

arch/sandbox/dts/test.dts

@@ -11,6 +11,8 @@
 		eth0 = "/eth@10002000";
 		eth3 = &eth_3;
 		eth5 = &eth_5;
+		gpio1 = &gpio_a;
+		gpio2 = &gpio_b;
 		i2c0 = "/i2c@0";
 		mmc0 = "/mmc0";
 		mmc1 = "/mmc1";
@@ -91,6 +93,15 @@
 		reg = <2 1>;
 	};
 
+	backlight: backlight {
+		compatible = "pwm-backlight";
+		enable-gpios = <&gpio_a 1>;
+		power-supply = <&ldo_1>;
+		pwms = <&pwm 0 1000>;
+		default-brightness-level = <5>;
+		brightness-levels = <0 16 32 64 128 170 202 234 255>;
+	};
+
 	bind-test {
 		bind-test-child1 {
 			compatible = "sandbox,phy";
@@ -441,12 +452,14 @@
 		power-domains = <&pwrdom 2>;
 	};
 
-	pwm {
+	pwm: pwm {
 		compatible = "sandbox,pwm";
+		#pwm-cells = <2>;
 	};
 
 	pwm2 {
 		compatible = "sandbox,pwm";
+		#pwm-cells = <2>;
 	};
 
 	ram {
@@ -483,6 +496,11 @@
 		remoteproc-name = "remoteproc-test-dev2";
 	};
 
+	panel {
+		compatible = "simple-panel";
+		backlight = <&backlight 0 100>;
+	};
+
 	smem@0 {
 		compatible = "sandbox,smem";
 	};

arch/sandbox/include/asm/test.h

@@ -98,4 +98,19 @@ int sandbox_usb_keyb_add_string(struct udevice *dev, const char *str);
  * @buflen:	length of buffer in bytes
  */
 int sandbox_osd_get_mem(struct udevice *dev, u8 *buf, size_t buflen);
+
+/**
+ * sandbox_pwm_get_config() - get the PWM config for a channel
+ *
+ * @dev: Device to check
+ * @channel: Channel number to check
+ * @period_ns: Period of the PWM in nanoseconds
+ * @duty_ns: Current duty cycle of the PWM in nanoseconds
+ * @enable: true if the PWM is enabled
+ * @polarity: true if the PWM polarity is active high
+ * @return 0 if OK, -ENOSPC if the PWM number is invalid
+ */
+int sandbox_pwm_get_config(struct udevice *dev, uint channel, uint *period_nsp,
+			   uint *duty_nsp, bool *enablep, bool *polarityp);
+
 #endif