linux-kernel - [PATCH 3/3] ARM: da850-lego-ev3: Add device tree node for sound

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Date:   Tue,  7 Feb 2017 13:22:09 -0600
From:   David Lechner <david@...hnology.com>
To:     linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org
Cc:     David Lechner <david@...hnology.com>, Sekhar Nori <nsekhar@...com>,
        Kevin Hilman <khilman@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] 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: David Lechner <david@...hnology.com>
---
 arch/arm/boot/dts/da850-lego-ev3.dts | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/arch/arm/boot/dts/da850-lego-ev3.dts b/arch/arm/boot/dts/da850-lego-ev3.dts
index 0309537..c20580a 100644
--- a/arch/arm/boot/dts/da850-lego-ev3.dts
+++ b/arch/arm/boot/dts/da850-lego-ev3.dts
@@ -123,6 +123,14 @@
 		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 @@
 		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 @@
 			0x4c 0x00008000 0x0000f000
 		>;
 	};
+
+	amp_pins: pinmux_amp_pins {
+		pinctrl-single,bits = <
+			/* GP6[15] */
+			0x34 0x00000008 0x0000000f
+		>;
+	};
 };
 
 &pinconf {
@@ -316,6 +343,10 @@
 	};
 };
 
+&ehrpwm0 {
+	status = "okay";
+};
+
 &gpio {
 	status = "okay";
 };
-- 
2.7.4