From dc2bd1c4b038c4f2d921808891b69a803805d984 Mon Sep 17 00:00:00 2001
From: Gordon Garrity <gordon@iqaudio.com>
Date: Sat, 8 Mar 2014 16:56:57 +0000
Subject: [PATCH] Add IQaudIO Sound Card support for Raspberry Pi

Set a limit of 0dB on Digital Volume Control

The main volume control in the PCM512x DAC has a range up to
+24dB. This is dangerously loud and can potentially cause massive
clipping in the output stages. Therefore this sets a sensible
limit of 0dB for this control.
---
 sound/soc/bcm/Kconfig       |   7 +++
 sound/soc/bcm/Makefile      |   2 +
 sound/soc/bcm/iqaudio-dac.c | 132 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 141 insertions(+)
 create mode 100644 sound/soc/bcm/iqaudio-dac.c

--- a/sound/soc/bcm/Kconfig
+++ b/sound/soc/bcm/Kconfig
@@ -28,3 +28,10 @@ config SND_BCM2708_SOC_RPI_DAC
         select SND_SOC_PCM1794A
         help
          Say Y or M if you want to add support for RPi-DAC.
+
+config SND_BCM2708_SOC_IQAUDIO_DAC
+	tristate "Support for IQaudIO-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 IQaudIO-DAC.
--- a/sound/soc/bcm/Makefile
+++ b/sound/soc/bcm/Makefile
@@ -7,7 +7,9 @@ obj-$(CONFIG_SND_BCM2835_SOC_I2S) += snd
 snd-soc-hifiberry-dac-objs := hifiberry_dac.o
 snd-soc-hifiberry-digi-objs := hifiberry_digi.o
 snd-soc-rpi-dac-objs := rpi-dac.o
+snd-soc-iqaudio-dac-objs := iqaudio-dac.o
 
 obj-$(CONFIG_SND_BCM2708_SOC_HIFIBERRY_DAC) += snd-soc-hifiberry-dac.o
 obj-$(CONFIG_SND_BCM2708_SOC_HIFIBERRY_DIGI) += snd-soc-hifiberry-digi.o
 obj-$(CONFIG_SND_BCM2708_SOC_RPI_DAC) += snd-soc-rpi-dac.o
+obj-$(CONFIG_SND_BCM2708_SOC_IQAUDIO_DAC) += snd-soc-iqaudio-dac.o
--- /dev/null
+++ b/sound/soc/bcm/iqaudio-dac.c
@@ -0,0 +1,132 @@
+/*
+ * ASoC Driver for IQaudIO DAC
+ *
+ * Author:	Florian Meier <florian.meier@koalo.de>
+ *		Copyright 2013
+ *
+ * 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>
+#include <sound/jack.h>
+
+static int snd_rpi_iqaudio_dac_init(struct snd_soc_pcm_runtime *rtd)
+{
+	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_rpi_iqaudio_dac_hw_params(struct snd_pcm_substream *substream,
+				       struct snd_pcm_hw_params *params)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+// NOT USED	struct snd_soc_dai *codec_dai = rtd->codec_dai;
+// NOT USED	struct snd_soc_codec *codec = rtd->codec;
+	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_rpi_iqaudio_dac_ops = {
+	.hw_params = snd_rpi_iqaudio_dac_hw_params,
+};
+
+static struct snd_soc_dai_link snd_rpi_iqaudio_dac_dai[] = {
+{
+	.name		= "IQaudIO DAC",
+	.stream_name	= "IQaudIO 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_rpi_iqaudio_dac_ops,
+	.init		= snd_rpi_iqaudio_dac_init,
+},
+};
+
+/* audio machine driver */
+static struct snd_soc_card snd_rpi_iqaudio_dac = {
+	.name         = "IQaudIODAC",
+	.dai_link     = snd_rpi_iqaudio_dac_dai,
+	.num_links    = ARRAY_SIZE(snd_rpi_iqaudio_dac_dai),
+};
+
+static int snd_rpi_iqaudio_dac_probe(struct platform_device *pdev)
+{
+	int ret = 0;
+
+	snd_rpi_iqaudio_dac.dev = &pdev->dev;
+
+	if (pdev->dev.of_node) {
+	    struct device_node *i2s_node;
+	    struct snd_soc_dai_link *dai = &snd_rpi_iqaudio_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;
+	    }
+	}
+
+	ret = snd_soc_register_card(&snd_rpi_iqaudio_dac);
+	if (ret)
+		dev_err(&pdev->dev,
+			"snd_soc_register_card() failed: %d\n", ret);
+
+	return ret;
+}
+
+static int snd_rpi_iqaudio_dac_remove(struct platform_device *pdev)
+{
+	return snd_soc_unregister_card(&snd_rpi_iqaudio_dac);
+}
+
+static const struct of_device_id iqaudio_of_match[] = {
+	{ .compatible = "iqaudio,iqaudio-dac", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, iqaudio_of_match);
+
+static struct platform_driver snd_rpi_iqaudio_dac_driver = {
+	.driver = {
+		.name   = "snd-rpi-iqaudio-dac",
+		.owner  = THIS_MODULE,
+		.of_match_table = iqaudio_of_match,
+	},
+	.probe          = snd_rpi_iqaudio_dac_probe,
+	.remove         = snd_rpi_iqaudio_dac_remove,
+};
+
+module_platform_driver(snd_rpi_iqaudio_dac_driver);
+
+MODULE_AUTHOR("Florian Meier <florian.meier@koalo.de>");
+MODULE_DESCRIPTION("ASoC Driver for IQAudio DAC");
+MODULE_LICENSE("GPL v2");
