ASoC: SAMSUNG: Add I2S soundcard using stub codec

HDMI can be configured to source audio data from I2S bus. For boards
on which there are no external audio chips, we still need to create
a I2S-based soundcard with a dummy codec driver to enable I2S subsystem
to pump data to the I2S bus, which can be used by HDMI module.

Signed-off-by: Tushar Behera <tushar.behera@linaro.org>

sound/soc/samsung/Kconfig

@@ -231,3 +231,12 @@ config SND_SOC_LITTLEMILL
 	select SND_SAMSUNG_I2S
 	select MFD_WM8994
 	select SND_SOC_WM8994
+
+config SND_SOC_SMDK_I2S_STUB
+	tristate "SoC I2S Audio support for boards without external codec chip"
+	depends on SND_SOC_SAMSUNG
+	select SND_SAMSUNG_I2S
+	select SND_SOC_I2S_STUB
+	help
+	  Say Y if you want to add support for SoC audio on boards without
+	  exteral codec chip.

sound/soc/samsung/Makefile

@@ -45,6 +45,7 @@ snd-soc-tobermory-objs := tobermory.o
 snd-soc-lowland-objs := lowland.o
 snd-soc-littlemill-objs := littlemill.o
 snd-soc-bells-objs := bells.o
+snd-soc-smdk-i2s-stub-objs := smdk_i2s_stub.o
 
 obj-$(CONFIG_SND_SOC_SAMSUNG_JIVE_WM8750) += snd-soc-jive-wm8750.o
 obj-$(CONFIG_SND_SOC_SAMSUNG_NEO1973_WM8753) += snd-soc-neo1973-wm8753.o
@@ -69,3 +70,4 @@ obj-$(CONFIG_SND_SOC_TOBERMORY) += snd-soc-tobermory.o
 obj-$(CONFIG_SND_SOC_LOWLAND) += snd-soc-lowland.o
 obj-$(CONFIG_SND_SOC_LITTLEMILL) += snd-soc-littlemill.o
 obj-$(CONFIG_SND_SOC_BELLS) += snd-soc-bells.o
+obj-$(CONFIG_SND_SOC_SMDK_I2S_STUB) += snd-soc-smdk-i2s-stub.o

sound/soc/samsung/smdk_i2s_stub.c

@@ -0,0 +1,166 @@
+/*
+ * Copyright (C) 2011 Insignal Co., Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/of.h>
+
+#include <sound/soc.h>
+#include <sound/soc-dapm.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+
+#include "i2s.h"
+
+static int smdk_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;
+	int bfs, ret;
+
+	switch (params_format(params)) {
+	case SNDRV_PCM_FORMAT_U24:
+	case SNDRV_PCM_FORMAT_S24:
+		bfs = 48;
+		break;
+	case SNDRV_PCM_FORMAT_U16_LE:
+	case SNDRV_PCM_FORMAT_S16_LE:
+		bfs = 32;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Set the AP DAI configuration */
+	ret = snd_soc_dai_set_fmt(cpu_dai, SND_SOC_DAIFMT_I2S |
+						SND_SOC_DAIFMT_NB_NF |
+						SND_SOC_DAIFMT_CBS_CFS);
+	if (ret < 0)
+		return ret;
+
+	ret = snd_soc_dai_set_sysclk(cpu_dai, SAMSUNG_I2S_CDCLK, 0,
+						SND_SOC_CLOCK_OUT);
+	if (ret < 0)
+		return ret;
+
+	ret = snd_soc_dai_set_clkdiv(cpu_dai, SAMSUNG_I2S_DIV_BCLK, bfs);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static struct snd_soc_ops smdk_ops = {
+	.hw_params = smdk_hw_params,
+};
+
+static int smdk_init_paiftx(struct snd_soc_pcm_runtime *rtd)
+{
+	struct snd_soc_codec *codec = rtd->codec;
+	struct snd_soc_dapm_context *dapm = &codec->dapm;
+
+	snd_soc_dapm_sync(dapm);
+
+	return 0;
+}
+
+static struct snd_soc_dai_link smdk_dai[] = {
+	{ /* Primary DAI i/f */
+		.name = "I2S",
+		.stream_name = "Pri_Dai",
+		.cpu_dai_name = "samsung-i2s.0",
+		.codec_dai_name = "i2s-stub-hifi",
+		.platform_name = "samsung-i2s.0",
+		.codec_name = "i2s-stub",
+		.init = smdk_init_paiftx,
+		.ops = &smdk_ops,
+	},
+};
+
+static struct snd_soc_card smdk = {
+	.name = "I2S-STUB",
+	.owner = THIS_MODULE,
+	.dai_link = smdk_dai,
+	.num_links = ARRAY_SIZE(smdk_dai),
+};
+
+static int smdk_audio_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct device_node *np = pdev->dev.of_node;
+	struct snd_soc_card *card = &smdk;
+	struct snd_soc_dai_link *dai_link = &smdk_dai[0];
+
+	card->dev = &pdev->dev;
+
+	if (np) {
+		dai_link->cpu_of_node = of_parse_phandle(np,
+				"samsung,i2s-controller", 0);
+		if (!dai_link->cpu_of_node) {
+			dev_err(&pdev->dev,
+				"Property 'samsung,i2s-controller' missing\n");
+			return -EINVAL;
+		}
+
+		dai_link->cpu_dai_name = NULL;
+		dai_link->platform_name = NULL;
+		dai_link->platform_of_node = dai_link->cpu_of_node;
+
+		dai_link->codec_of_node = of_parse_phandle(np,
+				"samsung,audio-codec", 0);
+		if (!dai_link->codec_of_node) {
+			dev_err(&pdev->dev,
+				"Property 'samsung,audio-codec' missing\n");
+			return -EINVAL;
+		}
+		dai_link->codec_name = NULL;
+	}
+
+	ret = snd_soc_register_card(card);
+
+	if (ret)
+		dev_err(&pdev->dev, "snd_soc_register_card() failed:%d\n", ret);
+
+	return ret;
+}
+
+static int smdk_audio_remove(struct platform_device *pdev)
+{
+	struct snd_soc_card *card = platform_get_drvdata(pdev);
+
+	snd_soc_unregister_card(card);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id samsung_i2s_stub_of_match[] = {
+	{ .compatible = "samsung,smdk-i2s-stub", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, samsung_wm8994_of_match);
+#endif /* CONFIG_OF */
+
+static struct platform_driver smdk_audio_driver = {
+	.driver		= {
+		.name	= "smdk-i2s-audio",
+		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(samsung_i2s_stub_of_match),
+	},
+	.probe		= smdk_audio_probe,
+	.remove		= smdk_audio_remove,
+};
+
+module_platform_driver(smdk_audio_driver);
+
+MODULE_AUTHOR("Tushar Behera");
+MODULE_DESCRIPTION("ALSA SoC I2S STUB");
+MODULE_LICENSE("GPL");