DT-overlays: adds support for Hifiberry AMP4 Pro

The AMP4 Pro uses a TI TAS5756 amplifier in master mode
and requires the DAC Plus card driver and the
pcm512x component driver with TAS support.

Signed-off-by: Joerg Schambacher <[email protected]>

Author: j-schambacher

arch/arm/boot/dts/overlays/Makefile

@@ -86,6 +86,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
 	hifiberry-amp.dtbo \
 	hifiberry-amp100.dtbo \
 	hifiberry-amp3.dtbo \
+	hifiberry-amp4pro.dtbo \
 	hifiberry-dac.dtbo \
 	hifiberry-dacplus.dtbo \
 	hifiberry-dacplusadc.dtbo \

arch/arm/boot/dts/overlays/README

@@ -1738,6 +1738,34 @@ Load:   dtoverlay=hifiberry-amp3
 Params: <None>
 
 
+Name:   hifiberry-amp4pro
+Info:   Configures the HifiBerry AMP4 Pro audio card
+Load:   dtoverlay=hifiberry-amp4pro,<param>=<val>
+Params: 24db_digital_gain       Allow gain to be applied via the TAS5756
+                                Digital volume control. Enable with
+                                "dtoverlay=hifiberry-amp4pro,24db_digital_gain"
+                                (The default behaviour is that the Digital
+                                volume control is limited to a maximum of
+                                0dB. ie. it can attenuate but not provide
+                                gain. For most users, this will be desired
+                                as it will prevent clipping. By appending
+                                the 24dB_digital_gain parameter, the Digital
+                                volume control will allow up to 24dB of
+                                gain. If this parameter is enabled, it is the
+                                responsibility of the user to ensure that
+                                the Digital volume control is set to a value
+                                that does not result in clipping/distortion!)
+        slave                   Force the amp into slave mode, using Pi as
+                                master for bit clock and frame clock.
+        leds_off                If set to 'true' the onboard indicator LEDs
+                                are switched off at all times.
+        auto_mute               If set to 'true' the amplifier is automatically
+                                muted when it is not playing.
+        mute_ext_ctl            The amplifier's HW mute control is enabled
+                                in ALSA mixer and set to <val>.
+                                Will be overwritten by ALSA user settings.
+
+
 Name:   hifiberry-dac
 Info:   Configures the HifiBerry DAC audio cards
 Load:   dtoverlay=hifiberry-dac

arch/arm/boot/dts/overlays/hifiberry-amp4pro-overlay.dts

@@ -0,0 +1,63 @@
+// Definitions for HiFiBerry AMP4PRO
+/dts-v1/;
+/plugin/;
+#include <dt-bindings/gpio/gpio.h>
+
+/ {
+	compatible = "brcm,bcm2835";
+
+	fragment@0 {
+		target-path = "/";
+		__overlay__ {
+			dacpro_osc: dacpro_osc {
+				compatible = "hifiberry,dacpro-clk";
+				#clock-cells = <0>;
+			};
+		};
+	};
+
+	frag1: fragment@1 {
+		target = <&i2s_clk_consumer>;
+		__overlay__ {
+			status = "okay";
+		};
+	};
+
+	fragment@2 {
+		target = <&i2c1>;
+		__overlay__ {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "okay";
+
+			tas5756@4d {
+				#sound-dai-cells = <0>;
+				compatible = "ti,tas5756";
+				reg = <0x4d>;
+				clocks = <&dacpro_osc>;
+				status = "okay";
+			};
+		};
+	};
+
+	fragment@3 {
+		target = <&sound>;
+		hifiberry_dacplus: __overlay__ {
+			compatible = "hifiberry,hifiberry-dacplus";
+			i2s-controller = <&i2s_clk_consumer>;
+			status = "okay";
+			mute-gpio = <&gpio 4 GPIO_ACTIVE_LOW>;
+		};
+	};
+
+	__overrides__ {
+		24db_digital_gain =
+			<&hifiberry_dacplus>,"hifiberry-amp4,24db_digital_gain?";
+		leds_off = <&hifiberry_dacplus>,"hifiberry-amp4,leds_off?";
+		mute_ext_ctl = <&hifiberry_dacplus>,"hifiberry-amp4,mute_ext_ctl:0";
+		auto_mute = <&hifiberry_dacplus>,"hifiberry-amp4,auto_mute?";
+		slave = <&hifiberry_dacplus>,"hifiberry-dacplus,slave?",
+			<&frag1>,"target:0=",<&i2s_clk_producer>,
+			<&hifiberry_dacplus>,"i2s-controller:0=",<&i2s_clk_producer>;
+	};
+};