Allo Piano DAC boards: Initial 2 channel (stereo) support

arch/arm/boot/dts/overlays/Makefile

@@ -16,6 +16,7 @@ dtbo-$(RPI_DT_OVERLAYS) += adau1977-adc.dtbo
 dtbo-$(RPI_DT_OVERLAYS) += ads1015.dtbo
 dtbo-$(RPI_DT_OVERLAYS) += ads7846.dtbo
 dtbo-$(RPI_DT_OVERLAYS) += akkordion-iqdacplus.dtbo
+dtbo-$(RPI_DT_OVERLAYS) += allo-piano-dac-pcm512x-audio.dtbo
 dtbo-$(RPI_DT_OVERLAYS) += at86rf233.dtbo
 dtbo-$(RPI_DT_OVERLAYS) += audioinjector-wm8731-audio.dtbo
 dtbo-$(RPI_DT_OVERLAYS) += audremap.dtbo

arch/arm/boot/dts/overlays/README

@@ -235,6 +235,26 @@ Params: 24db_digital_gain       Allow gain to be applied via the PCM512x codec
                                 that does not result in clipping/distortion!)
 
 
+Name:   allo-piano-dac-pcm512x-audio
+Info:   Configures the Allo Piano DAC (2.0/2.1) audio cards.
+        (NB. This initial support is for 2.0 channel audio ONLY! ie. stereo.
+        The subwoofer outputs on the Piano 2.1 are not currently supported!)
+Load:   dtoverlay=allo-piano-dac-pcm512x-audio,<param>
+Params: 24db_digital_gain       Allow gain to be applied via the PCM512x codec
+                                Digital volume control.
+                                (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!)
+
+
 Name:   at86rf233
 Info:   Configures the Atmel AT86RF233 802.15.4 low-power WPAN transceiver,
         connected to spi0.0

arch/arm/boot/dts/overlays/allo-piano-dac-pcm512x-audio-overlay.dts

@@ -0,0 +1,54 @@
+/*
+ * Definitions for Allo Piano DAC (2.0/2.1) boards
+ *
+ * NB. The Piano DAC 2.1 board contains 2x TI PCM5142 DAC's. One DAC is stereo
+ * (left/right) and the other provides a subwoofer output, using DSP on the
+ * chip for digital high/low pass crossover.
+ * The initial support for this hardware, that doesn't require any codec driver
+ * modifications, uses only one DAC chip for stereo (left/right) output, the
+ * chip with 0x4c slave address. The other chip at 0x4d is currently ignored!
+ */
+
+/dts-v1/;
+/plugin/;
+
+/ {
+	compatible = "brcm,bcm2708";
+
+	fragment@0 {
+		target = <&i2s>;
+		__overlay__ {
+			status = "okay";
+		};
+	};
+
+	fragment@1 {
+		target = <&i2c1>;
+		__overlay__ {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "okay";
+
+			pcm5142@4c {
+				#sound-dai-cells = <0>;
+				compatible = "ti,pcm5142";
+				reg = <0x4c>;
+				status = "okay";
+			};
+		};
+	};
+
+	fragment@2 {
+		target = <&sound>;
+		piano_dac: __overlay__ {
+			compatible = "allo,piano-dac";
+			i2s-controller = <&i2s>;
+			status = "okay";
+		};
+	};
+
+	__overrides__ {
+		24db_digital_gain =
+			<&piano_dac>,"allo,24db_digital_gain?";
+	};
+};

arch/arm/configs/bcm2709_defconfig

@@ -879,6 +879,7 @@ CONFIG_SND_BCM2708_SOC_ADAU1977_ADC=m
 CONFIG_SND_AUDIOINJECTOR_PI_SOUNDCARD=m
 CONFIG_SND_DIGIDAC1_SOUNDCARD=m
 CONFIG_SND_BCM2708_SOC_DIONAUDIO_LOCO=m
+CONFIG_SND_BCM2708_SOC_ALLO_PIANO_DAC=m
 CONFIG_SND_SOC_ADAU1701=m
 CONFIG_SND_SOC_WM8804_I2C=m
 CONFIG_SND_SIMPLE_CARD=m

arch/arm/configs/bcmrpi_defconfig

@@ -871,6 +871,7 @@ CONFIG_SND_BCM2708_SOC_ADAU1977_ADC=m
 CONFIG_SND_AUDIOINJECTOR_PI_SOUNDCARD=m
 CONFIG_SND_DIGIDAC1_SOUNDCARD=m
 CONFIG_SND_BCM2708_SOC_DIONAUDIO_LOCO=m
+CONFIG_SND_BCM2708_SOC_ALLO_PIANO_DAC=m
 CONFIG_SND_SOC_ADAU1701=m
 CONFIG_SND_SOC_WM8804_I2C=m
 CONFIG_SND_SIMPLE_CARD=m

sound/soc/bcm/Kconfig

@@ -114,3 +114,10 @@ config SND_BCM2708_SOC_DIONAUDIO_LOCO
 	select SND_SOC_PCM5102a
 	help
 	  Say Y or M if you want to add support for Dion Audio LOCO.
+
+config SND_BCM2708_SOC_ALLO_PIANO_DAC
+	tristate "Support for Allo Piano DAC"
+	depends on SND_BCM2708_SOC_I2S || SND_BCM2835_SOC_I2S
+	select SND_SOC_PCM512x_I2C
+	help
+	  Say Y or M if you want to add support for Allo Piano DAC.

sound/soc/bcm/Makefile

@@ -19,6 +19,7 @@ snd-soc-raspidac3-objs := raspidac3.o
 snd-soc-audioinjector-pi-soundcard-objs := audioinjector-pi-soundcard.o
 snd-soc-digidac1-soundcard-objs := digidac1-soundcard.o
 snd-soc-dionaudio-loco-objs := dionaudio_loco.o
+snd-soc-allo-piano-dac-objs := allo-piano-dac.o
 
 obj-$(CONFIG_SND_BCM2708_SOC_ADAU1977_ADC) += snd-soc-adau1977-adc.o
 obj-$(CONFIG_SND_BCM2708_SOC_HIFIBERRY_DAC) += snd-soc-hifiberry-dac.o
@@ -35,3 +36,4 @@ obj-$(CONFIG_SND_BCM2708_SOC_RASPIDAC3) += snd-soc-raspidac3.o
 obj-$(CONFIG_SND_AUDIOINJECTOR_PI_SOUNDCARD) += snd-soc-audioinjector-pi-soundcard.o
 obj-$(CONFIG_SND_DIGIDAC1_SOUNDCARD) += snd-soc-digidac1-soundcard.o
 obj-$(CONFIG_SND_BCM2708_SOC_DIONAUDIO_LOCO) += snd-soc-dionaudio-loco.o
+obj-$(CONFIG_SND_BCM2708_SOC_ALLO_PIANO_DAC) += snd-soc-allo-piano-dac.o

sound/soc/bcm/allo-piano-dac.c

@@ -0,0 +1,144 @@
+/*
+ * ALSA ASoC Machine Driver for Allo Piano DAC
+ *
+ * Author:	Baswaraj K <[email protected]>
+ *		Copyright 2016
+ *		based on code by Daniel Matuschek <[email protected]>
+ *		based on code by Florian Meier <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+
+static bool digital_gain_0db_limit = true;
+
+static int snd_allo_piano_dac_init(struct snd_soc_pcm_runtime *rtd)
+{
+	if (digital_gain_0db_limit) {
+		int ret;
+		struct snd_soc_card *card = rtd->card;
+
+		ret = snd_soc_limit_volume(card, "Digital Playback Volume",
+					   207);
+		if (ret < 0)
+			dev_warn(card->dev, "Failed to set volume limit: %d\n",
+				 ret);
+	}
+
+	return 0;
+}
+
+static int snd_allo_piano_dac_hw_params(
+	struct snd_pcm_substream *substream, struct snd_pcm_hw_params *params)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
+
+	unsigned int sample_bits =
+		snd_pcm_format_physical_width(params_format(params));
+
+	return snd_soc_dai_set_bclk_ratio(cpu_dai, sample_bits * 2);
+}
+
+/* machine stream operations */
+static struct snd_soc_ops snd_allo_piano_dac_ops = {
+	.hw_params = snd_allo_piano_dac_hw_params,
+};
+
+static struct snd_soc_dai_link snd_allo_piano_dac_dai[] = {
+{
+	.name		= "Piano DAC",
+	.stream_name	= "Piano DAC HiFi",
+	.cpu_dai_name	= "bcm2708-i2s.0",
+	.codec_dai_name	= "pcm512x-hifi",
+	.platform_name	= "bcm2708-i2s.0",
+	.codec_name	= "pcm512x.1-004c",
+	.dai_fmt	= SND_SOC_DAIFMT_I2S |
+			  SND_SOC_DAIFMT_NB_NF |
+			  SND_SOC_DAIFMT_CBS_CFS,
+	.ops		= &snd_allo_piano_dac_ops,
+	.init		= snd_allo_piano_dac_init,
+},
+};
+
+/* audio machine driver */
+static struct snd_soc_card snd_allo_piano_dac = {
+	.name         = "PianoDAC",
+	.owner        = THIS_MODULE,
+	.dai_link     = snd_allo_piano_dac_dai,
+	.num_links    = ARRAY_SIZE(snd_allo_piano_dac_dai),
+};
+
+static int snd_allo_piano_dac_probe(struct platform_device *pdev)
+{
+	int ret = 0;
+
+	snd_allo_piano_dac.dev = &pdev->dev;
+
+	if (pdev->dev.of_node) {
+		struct device_node *i2s_node;
+		struct snd_soc_dai_link *dai;
+
+		dai = &snd_allo_piano_dac_dai[0];
+		i2s_node = of_parse_phandle(pdev->dev.of_node,
+					    "i2s-controller", 0);
+
+		if (i2s_node) {
+			dai->cpu_dai_name = NULL;
+			dai->cpu_of_node = i2s_node;
+			dai->platform_name = NULL;
+			dai->platform_of_node = i2s_node;
+		}
+
+		digital_gain_0db_limit = !of_property_read_bool(
+			pdev->dev.of_node, "allo,24db_digital_gain");
+	}
+
+	ret = snd_soc_register_card(&snd_allo_piano_dac);
+	if (ret)
+		dev_err(&pdev->dev,
+			"snd_soc_register_card() failed: %d\n", ret);
+
+	return ret;
+}
+
+static int snd_allo_piano_dac_remove(struct platform_device *pdev)
+{
+	return snd_soc_unregister_card(&snd_allo_piano_dac);
+}
+
+static const struct of_device_id snd_allo_piano_dac_of_match[] = {
+	{ .compatible = "allo,piano-dac", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, snd_allo_piano_dac_of_match);
+
+static struct platform_driver snd_allo_piano_dac_driver = {
+	.driver = {
+		.name   = "snd-allo-piano-dac",
+		.owner  = THIS_MODULE,
+		.of_match_table = snd_allo_piano_dac_of_match,
+	},
+	.probe          = snd_allo_piano_dac_probe,
+	.remove         = snd_allo_piano_dac_remove,
+};
+
+module_platform_driver(snd_allo_piano_dac_driver);
+
+MODULE_AUTHOR("Baswaraj K <[email protected]>");
+MODULE_DESCRIPTION("ALSA ASoC Machine Driver for Allo Piano DAC");
+MODULE_LICENSE("GPL v2");