ARM: da850-lego-ev3: Add device tree node for sound

This adds a device tree node for sound on LEGO MINDSTORMS EV3. The EV3
uses one of the SoC PWMs connected to an amplifier to create sound from
a speaker.

The PWM is passed through a low-pass filter, so it is actually possible
to do PCM playback, but there is no existing driver, so just using
pwm-beeper for now, since it is also a compatible mode of operation.
Signed-off-by: NDavid Lechner <david@lechnology.com>
Signed-off-by: NSekhar Nori <nsekhar@ti.com>

arch/arm/boot/dts/da850-lego-ev3.dts

@@ -123,6 +123,14 @@ gpio-poweroff {
 		pinctrl-0 = <&system_power_pin>;
 	};
 
+	sound {
+		compatible = "pwm-beeper";
+		pinctrl-names = "default";
+		pinctrl-0 = <&ehrpwm0b_pins>;
+		pwms = <&ehrpwm0 1 1000000 0>;
+		amp-supply = <&amp>;
+	};
+
 	/*
 	 * This is a 5V current limiting regulator that is shared by USB,
 	 * the sensor (input) ports, the motor (output) ports and the A/DC.
@@ -152,6 +160,18 @@ adc_ref: regulator2 {
 		regulator-boot-on;
 		vin-supply = <&vcc5v>;
 	};
+
+	/*
+	 * This is the amplifier for the speaker.
+	 */
+	amp: regulator3 {
+		pinctrl-names = "default";
+		pinctrl-0 = <&amp_pins>;
+		compatible = "regulator-fixed";
+		regulator-name = "amp";
+		gpio = <&gpio 111 GPIO_ACTIVE_HIGH>;
+		enable-active-high;
+	};
 };
 
 &pmx_core {
@@ -208,6 +228,13 @@ vcc5v_pins: pinmux_vcc5v {
 			0x4c 0x00008000 0x0000f000
 		>;
 	};
+
+	amp_pins: pinmux_amp_pins {
+		pinctrl-single,bits = <
+			/* GP6[15] */
+			0x34 0x00000008 0x0000000f
+		>;
+	};
 };
 
 &pinconf {
@@ -316,6 +343,10 @@ adc: adc@3 {
 	};
 };
 
+&ehrpwm0 {
+	status = "okay";
+};
+
 &gpio {
 	status = "okay";
 };