ASoC: Add support for Conexant CX20442-11 voice modem codec

This patch adds support for Conexant CX20442-11 voice modem codec, suitable
for use by the ASoC board driver for Amstrad E3 (Delta) videophone. Related
sound card driver will follow.

This codec is an optional part of the Conexant SmartV three chip modem design.
As such, documentation for its proprietary digital audio interface is not
available. However, on Amstrad Delta board, thanks to Mark Underwood who
created an initial, omap-alsa based sound driver a few years ago[1], the codec
has been discovered to be accessible not only from the modem side, but also
over the OMAP McBSP based CPU DAI. Thus, the driver can be used by any sound
card that can access the codec DAI directly. The DAI configuration parameters
(sample rate and format, number of channels) has been selected out empirically
for best user experience.

The codec analogue interface consists of two pairs of analogue I/O pins:
speakerphone interface or telephone handset/headset interface. Furthermore, it
seams to provide two operation modes for speakerphone I/O: standard and
advanced, with automatic gain control and echo cancelation. Even if the codec
control interface is unknown and not available, all those interfaces and modes
can be selected over the modem chip using V.253 commands. The driver is able
to issue necessary commands over a suitable hw_write function if provided by a
sound card driver. Otherwise, the codec can be controlled over the modem from
userspace while inactive.

Even if nothig is known about the codec internal power management
capabilities, DAPM widgets has been used to model the codec audio map.
Automatically performed powering up/down of those virtual widgets results in
corresponding V.253 commands being issued.

Some driver features/oddities may be board specific, but I have no way to
verify that with any board other than Amstrad Delta.

[1] http://www.earth.li/pipermail/e3-hacking/2006-April/000481.html

Created and tested against linux-2.6.31-rc3.
Applies and works with linux-omap-2.6 commit
7c5cb7862d32cb344be7831d466535d5255e35ac as well.
Signed-off-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/codecs/Kconfig

@@ -94,6 +94,9 @@ config SND_SOC_CS4270_VD33_ERRATA
 	bool
 	depends on SND_SOC_CS4270
 
+config SND_SOC_CX20442
+	tristate
+
 config SND_SOC_L3
        tristate
 

sound/soc/codecs/Makefile

@@ -5,6 +5,7 @@ snd-soc-ad73311-objs := ad73311.o
 snd-soc-ak4104-objs := ak4104.o
 snd-soc-ak4535-objs := ak4535.o
 snd-soc-cs4270-objs := cs4270.o
+snd-soc-cx20442-objs := cx20442.o
 snd-soc-l3-objs := l3.o
 snd-soc-pcm3008-objs := pcm3008.o
 snd-soc-spdif-objs := spdif_transciever.o
@@ -49,6 +50,7 @@ obj-$(CONFIG_SND_SOC_AD73311) += snd-soc-ad73311.o
 obj-$(CONFIG_SND_SOC_AK4104)	+= snd-soc-ak4104.o
 obj-$(CONFIG_SND_SOC_AK4535)	+= snd-soc-ak4535.o
 obj-$(CONFIG_SND_SOC_CS4270)	+= snd-soc-cs4270.o
+obj-$(CONFIG_SND_SOC_CX20442)	+= snd-soc-cx20442.o
 obj-$(CONFIG_SND_SOC_L3)	+= snd-soc-l3.o
 obj-$(CONFIG_SND_SOC_PCM3008)	+= snd-soc-pcm3008.o
 obj-$(CONFIG_SND_SOC_SPDIF)	+= snd-soc-spdif.o

sound/soc/codecs/cx20442.c

+/*
+ * cx20442.c  --  CX20442 ALSA Soc Audio driver
+ *
+ * Copyright 2009 Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
+ *
+ * Initially based on sound/soc/codecs/wm8400.c
+ * Copyright 2008, 2009 Wolfson Microelectronics PLC.
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ *
+ *  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 <sound/core.h>
+#include <sound/initval.h>
+#include <sound/soc-dapm.h>
+
+#include "cx20442.h"
+
+
+struct cx20442_priv {
+	struct snd_soc_codec codec;
+	u8 reg_cache[1];
+};
+
+#define CX20442_PM		0x0
+
+#define CX20442_TELIN		0
+#define CX20442_TELOUT		1
+#define CX20442_MIC		2
+#define CX20442_SPKOUT		3
+#define CX20442_AGC		4
+
+static const struct snd_soc_dapm_widget cx20442_dapm_widgets[] = {
+	SND_SOC_DAPM_OUTPUT("TELOUT"),
+	SND_SOC_DAPM_OUTPUT("SPKOUT"),
+	SND_SOC_DAPM_OUTPUT("AGCOUT"),
+
+	SND_SOC_DAPM_MIXER("SPKOUT Mixer", SND_SOC_NOPM, 0, 0, NULL, 0),
+
+	SND_SOC_DAPM_PGA("TELOUT Amp", CX20442_PM, CX20442_TELOUT, 0, NULL, 0),
+	SND_SOC_DAPM_PGA("SPKOUT Amp", CX20442_PM, CX20442_SPKOUT, 0, NULL, 0),
+	SND_SOC_DAPM_PGA("SPKOUT AGC", CX20442_PM, CX20442_AGC, 0, NULL, 0),
+
+	SND_SOC_DAPM_DAC("DAC", "Playback", SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_ADC("ADC", "Capture", SND_SOC_NOPM, 0, 0),
+
+	SND_SOC_DAPM_MIXER("Input Mixer", SND_SOC_NOPM, 0, 0, NULL, 0),
+
+	SND_SOC_DAPM_MICBIAS("TELIN Bias", CX20442_PM, CX20442_TELIN, 0),
+	SND_SOC_DAPM_MICBIAS("MIC Bias", CX20442_PM, CX20442_MIC, 0),
+
+	SND_SOC_DAPM_PGA("MIC AGC", CX20442_PM, CX20442_AGC, 0, NULL, 0),
+
+	SND_SOC_DAPM_INPUT("TELIN"),
+	SND_SOC_DAPM_INPUT("MIC"),
+	SND_SOC_DAPM_INPUT("AGCIN"),
+};
+
+static const struct snd_soc_dapm_route cx20442_audio_map[] = {
+	{"TELOUT", NULL, "TELOUT Amp"},
+
+	{"SPKOUT", NULL, "SPKOUT Mixer"},
+	{"SPKOUT Mixer", NULL, "SPKOUT Amp"},
+
+	{"TELOUT Amp", NULL, "DAC"},
+	{"SPKOUT Amp", NULL, "DAC"},
+
+	{"SPKOUT Mixer", NULL, "SPKOUT AGC"},
+	{"SPKOUT AGC", NULL, "AGCIN"},
+
+	{"AGCOUT", NULL, "MIC AGC"},
+	{"MIC AGC", NULL, "MIC"},
+
+	{"MIC Bias", NULL, "MIC"},
+	{"Input Mixer", NULL, "MIC Bias"},
+
+	{"TELIN Bias", NULL, "TELIN"},
+	{"Input Mixer", NULL, "TELIN Bias"},
+
+	{"ADC", NULL, "Input Mixer"},
+};
+
+static int cx20442_add_widgets(struct snd_soc_codec *codec)
+{
+	snd_soc_dapm_new_controls(codec, cx20442_dapm_widgets,
+				  ARRAY_SIZE(cx20442_dapm_widgets));
+
+	snd_soc_dapm_add_routes(codec, cx20442_audio_map,
+				ARRAY_SIZE(cx20442_audio_map));
+
+	snd_soc_dapm_new_widgets(codec);
+	return 0;
+}
+
+static unsigned int cx20442_read_reg_cache(struct snd_soc_codec *codec,
+							unsigned int reg)
+{
+	u8 *reg_cache = codec->reg_cache;
+
+	if (reg >= codec->reg_cache_size)
+		return -EINVAL;
+
+	return reg_cache[reg];
+}
+
+enum v253_vls {
+	V253_VLS_NONE = 0,
+	V253_VLS_T,
+	V253_VLS_L,
+	V253_VLS_LT,
+	V253_VLS_S,
+	V253_VLS_ST,
+	V253_VLS_M,
+	V253_VLS_MST,
+	V253_VLS_S1,
+	V253_VLS_S1T,
+	V253_VLS_MS1T,
+	V253_VLS_M1,
+	V253_VLS_M1ST,
+	V253_VLS_M1S1T,
+	V253_VLS_H,
+	V253_VLS_HT,
+	V253_VLS_MS,
+	V253_VLS_MS1,
+	V253_VLS_M1S,
+	V253_VLS_M1S1,
+	V253_VLS_TEST,
+};
+
+static int cx20442_pm_to_v253_vls(u8 value)
+{
+	switch(value & ~(1 << CX20442_AGC)) {
+	case 0:
+		return V253_VLS_T;
+	case (1 << CX20442_SPKOUT):
+		return V253_VLS_S1;
+	case (1 << CX20442_MIC):
+		return V253_VLS_M1;
+	case (1 << CX20442_SPKOUT) | (1 << CX20442_MIC):
+		return V253_VLS_M1S1;
+	case (1 << CX20442_TELOUT):
+	case (1 << CX20442_TELIN):
+	case (1 << CX20442_TELOUT) | (1 << CX20442_TELIN):
+		return V253_VLS_L;
+	case (1 << CX20442_TELOUT) | (1 << CX20442_MIC):
+		return V253_VLS_NONE;
+	}
+	return -EINVAL;
+}
+static int cx20442_pm_to_v253_vsp(u8 value)
+{
+	switch(value & ~(1 << CX20442_AGC)) {
+	case (1 << CX20442_SPKOUT):
+	case (1 << CX20442_MIC):
+	case (1 << CX20442_SPKOUT) | (1 << CX20442_MIC):
+		return (bool)(value & (1 << CX20442_AGC));
+	}
+	return (value & (1 << CX20442_AGC)) ? -EINVAL : 0;
+}
+
+static int cx20442_write(struct snd_soc_codec *codec, unsigned int reg,
+							unsigned int value)
+{
+	u8 *reg_cache = codec->reg_cache;
+	int vls, vsp, old, len;
+	char buf[18];
+
+	if (reg >= codec->reg_cache_size)
+		return -EINVAL;
+
+	if (!codec->hw_write || !codec->control_data)
+		return -EIO;
+
+	old = reg_cache[reg];
+	reg_cache[reg] = value;
+
+	vls = cx20442_pm_to_v253_vls(value);
+	if (vls < 0)
+		return vls;
+
+	vsp = cx20442_pm_to_v253_vsp(value);
+	if (vsp < 0 )
+		return vsp;
+
+	if ((vls == V253_VLS_T) ||
+			(vls == cx20442_pm_to_v253_vls(old))) {
+		if (vsp == cx20442_pm_to_v253_vsp(old))
+			return 0;
+		len = snprintf(buf, ARRAY_SIZE(buf), "at+vsp=%d\r", vsp);
+	} else if (vsp == cx20442_pm_to_v253_vsp(old))
+		len = snprintf(buf, ARRAY_SIZE(buf), "at+vls=%d\r", vls);
+	else
+		len = snprintf(buf, ARRAY_SIZE(buf),
+					"at+vls=%d;+vsp=%d\r", vls, vsp);
+
+	if (unlikely(len > (ARRAY_SIZE(buf) - 1)))
+		return -ENOMEM;
+
+	if (codec->hw_write(codec->control_data, buf, len) != len)
+		return -EIO;
+
+	return 0;
+}
+
+struct snd_soc_dai cx20442_dai = {
+	.name = "CX20442",
+	.playback = {
+		.stream_name = "Playback",
+		.channels_min = 1,
+		.channels_max = 1,
+		.rates = SNDRV_PCM_RATE_8000,
+		.formats = SNDRV_PCM_FMTBIT_S16_LE,
+	},
+	.capture = {
+		.stream_name = "Capture",
+		.channels_min = 1,
+		.channels_max = 1,
+		.rates = SNDRV_PCM_RATE_8000,
+		.formats = SNDRV_PCM_FMTBIT_S16_LE,
+	},
+};
+EXPORT_SYMBOL_GPL(cx20442_dai);
+
+static struct snd_soc_codec *cx20442_codec;
+
+static int cx20442_codec_probe(struct platform_device *pdev)
+{
+	struct snd_soc_device *socdev = platform_get_drvdata(pdev);
+	struct snd_soc_codec *codec;
+	int ret;
+
+	if(!cx20442_codec) {
+		dev_err(&pdev->dev, "cx20442 not yet discovered\n");
+		return -ENODEV;
+	}
+	codec = cx20442_codec;
+
+	socdev->card->codec = codec;
+
+	/* register pcms */
+	ret = snd_soc_new_pcms(socdev, SNDRV_DEFAULT_IDX1, SNDRV_DEFAULT_STR1);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to create pcms\n");
+		goto pcm_err;
+	}
+
+	cx20442_add_widgets(codec);
+
+	ret = snd_soc_init_card(socdev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to register card\n");
+		goto card_err;
+	}
+
+	return ret;
+
+card_err:
+	snd_soc_free_pcms(socdev);
+	snd_soc_dapm_free(socdev);
+pcm_err:
+	return ret;
+}
+
+/* power down chip */
+static int cx20442_codec_remove(struct platform_device *pdev)
+{
+	struct snd_soc_device *socdev = platform_get_drvdata(pdev);
+
+	snd_soc_free_pcms(socdev);
+	snd_soc_dapm_free(socdev);
+
+	return 0;
+}
+
+struct snd_soc_codec_device cx20442_codec_dev = {
+	.probe = 	cx20442_codec_probe,
+	.remove = 	cx20442_codec_remove,
+};
+EXPORT_SYMBOL_GPL(cx20442_codec_dev);
+
+static int cx20442_register(struct cx20442_priv *cx20442)
+{
+	struct snd_soc_codec *codec = &cx20442->codec;
+	int ret;
+
+	mutex_init(&codec->mutex);
+	INIT_LIST_HEAD(&codec->dapm_widgets);
+	INIT_LIST_HEAD(&codec->dapm_paths);
+
+	codec->name = "CX20442";
+	codec->owner = THIS_MODULE;
+	codec->private_data = cx20442;
+
+	codec->dai = &cx20442_dai;
+	codec->num_dai = 1;
+
+	codec->reg_cache = &cx20442->reg_cache;
+	codec->reg_cache_size = ARRAY_SIZE(cx20442->reg_cache);
+	codec->read = cx20442_read_reg_cache;
+	codec->write = cx20442_write;
+
+	codec->bias_level = SND_SOC_BIAS_OFF;
+
+	cx20442_dai.dev = codec->dev;
+
+	cx20442_codec = codec;
+
+	ret = snd_soc_register_codec(codec);
+	if (ret != 0) {
+		//dev_err(&dev->dev, "Failed to register codec: %d\n", ret);
+		goto err;
+	}
+
+	ret = snd_soc_register_dai(&cx20442_dai);
+	if (ret != 0) {
+		//dev_err(&dev->dev, "Failed to register DAI: %d\n", ret);
+		goto err_codec;
+	}
+
+	return 0;
+
+err_codec:
+	snd_soc_unregister_codec(codec);
+err:
+	cx20442_codec = NULL;
+	kfree(cx20442);
+	return ret;
+}
+
+static void cx20442_unregister(struct cx20442_priv *cx20442)
+{
+	snd_soc_unregister_dai(&cx20442_dai);
+	snd_soc_unregister_codec(&cx20442->codec);
+
+	cx20442_codec = NULL;
+	kfree(cx20442);
+}
+
+static int cx20442_platform_probe(struct platform_device *pdev)
+{
+	struct cx20442_priv *cx20442;
+	struct snd_soc_codec *codec;
+
+	cx20442 = kzalloc(sizeof(struct cx20442_priv), GFP_KERNEL);
+	if (cx20442 == NULL)
+		return -ENOMEM;
+
+	codec = &cx20442->codec;
+
+	codec->control_data = NULL;
+	codec->hw_write = NULL;
+	codec->pop_time = 0;
+
+	codec->dev = &pdev->dev;
+	platform_set_drvdata(pdev, cx20442);
+
+	return cx20442_register(cx20442);
+}
+
+static int __exit cx20442_platform_remove(struct platform_device *pdev)
+{
+	struct cx20442_priv *cx20442 = platform_get_drvdata(pdev);
+
+	cx20442_unregister(cx20442);
+	return 0;
+}
+
+static struct platform_driver cx20442_platform_driver = {
+	.driver = {
+		.name = "cx20442",
+		.owner = THIS_MODULE,
+		},
+	.probe = cx20442_platform_probe,
+	.remove = __exit_p(cx20442_platform_remove),
+};
+
+static int __init cx20442_init(void)
+{
+	return platform_driver_register(&cx20442_platform_driver);
+}
+module_init(cx20442_init);
+
+static void __exit cx20442_exit(void)
+{
+	platform_driver_unregister(&cx20442_platform_driver);
+}
+module_exit(cx20442_exit);
+
+MODULE_DESCRIPTION("ASoC CX20442-11 voice modem codec driver");
+MODULE_AUTHOR("Janusz Krzysztofik");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:cx20442-codec");

sound/soc/codecs/cx20442.h

+/*
+ * cx20442.h  --  audio driver for CX20442
+ *
+ * Copyright 2009 Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
+ *
+ *  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.
+ *
+ */
+
+#ifndef _CX20442_CODEC_H
+#define _CX20442_CODEC_H
+
+extern struct snd_soc_dai cx20442_dai;
+extern struct snd_soc_codec_device cx20442_codec_dev;
+
+#endif