ASoC: add support for TAS5720 digital amplifier

The Texas Instruments TAS5720L/M device is a high-efficiency mono
Class-D audio power amplifier optimized for high transient power
capability to use the dynamic power headroom of small loudspeakers.
Its digital time division multiplexed (TDM) interface enables up to
16 devices to share the same bus.

Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 620 insertions, 0 deletions

diff --git a/sound/soc/codecs/tas5720.c b/sound/soc/codecs/tas5720.c
new file mode 100644
index 000000000000..f54fb46b77c2
--- /dev/null
+++ b/sound/soc/codecs/tas5720.c
@@ -0,0 +1,620 @@
+/*
+ * tas5720.c - ALSA SoC Texas Instruments TAS5720 Mono Audio Amplifier
+ *
+ * Copyright (C)2015-2016 Texas Instruments Incorporated -  http://www.ti.com
+ *
+ * Author: Andreas Dannenberg <dannenberg@ti.com>
+ *
+ * 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/errno.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/regulator/consumer.h>
+#include <linux/delay.h>
+
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/soc-dapm.h>
+#include <sound/tlv.h>
+
+#include "tas5720.h"
+
+/* Define how often to check (and clear) the fault status register (in ms) */
+#define TAS5720_FAULT_CHECK_INTERVAL		200
+
+static const char * const tas5720_supply_names[] = {
+	"dvdd",		/* Digital power supply. Connect to 3.3-V supply. */
+	"pvdd",		/* Class-D amp and analog power supply (connected). */
+};
+
+#define TAS5720_NUM_SUPPLIES	ARRAY_SIZE(tas5720_supply_names)
+
+struct tas5720_data {
+	struct snd_soc_codec *codec;
+	struct regmap *regmap;
+	struct i2c_client *tas5720_client;
+	struct regulator_bulk_data supplies[TAS5720_NUM_SUPPLIES];
+	struct delayed_work fault_check_work;
+	unsigned int last_fault;
+};
+
+static int tas5720_hw_params(struct snd_pcm_substream *substream,
+			     struct snd_pcm_hw_params *params,
+			     struct snd_soc_dai *dai)
+{
+	struct snd_soc_codec *codec = dai->codec;
+	unsigned int rate = params_rate(params);
+	bool ssz_ds;
+	int ret;
+
+	switch (rate) {
+	case 44100:
+	case 48000:
+		ssz_ds = false;
+		break;
+	case 88200:
+	case 96000:
+		ssz_ds = true;
+		break;
+	default:
+		dev_err(codec->dev, "unsupported sample rate: %u\n", rate);
+		return -EINVAL;
+	}
+
+	ret = snd_soc_update_bits(codec, TAS5720_DIGITAL_CTRL1_REG,
+				  TAS5720_SSZ_DS, ssz_ds);
+	if (ret < 0) {
+		dev_err(codec->dev, "error setting sample rate: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int tas5720_set_dai_fmt(struct snd_soc_dai *dai, unsigned int fmt)
+{
+	struct snd_soc_codec *codec = dai->codec;
+	u8 serial_format;
+	int ret;
+
+	if ((fmt & SND_SOC_DAIFMT_MASTER_MASK) != SND_SOC_DAIFMT_CBS_CFS) {
+		dev_vdbg(codec->dev, "DAI Format master is not found\n");
+		return -EINVAL;
+	}
+
+	switch (fmt & (SND_SOC_DAIFMT_FORMAT_MASK |
+		       SND_SOC_DAIFMT_INV_MASK)) {
+	case (SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_NF):
+		/* 1st data bit occur one BCLK cycle after the frame sync */
+		serial_format = TAS5720_SAIF_I2S;
+		break;
+	case (SND_SOC_DAIFMT_DSP_A | SND_SOC_DAIFMT_NB_NF):
+		/*
+		 * Note that although the TAS5720 does not have a dedicated DSP
+		 * mode it doesn't care about the LRCLK duty cycle during TDM
+		 * operation. Therefore we can use the device's I2S mode with
+		 * its delaying of the 1st data bit to receive DSP_A formatted
+		 * data. See device datasheet for additional details.
+		 */
+		serial_format = TAS5720_SAIF_I2S;
+		break;
+	case (SND_SOC_DAIFMT_DSP_B | SND_SOC_DAIFMT_NB_NF):
+		/*
+		 * Similar to DSP_A, we can use the fact that the TAS5720 does
+		 * not care about the LRCLK duty cycle during TDM to receive
+		 * DSP_B formatted data in LEFTJ mode (no delaying of the 1st
+		 * data bit).
+		 */
+		serial_format = TAS5720_SAIF_LEFTJ;
+		break;
+	case (SND_SOC_DAIFMT_LEFT_J | SND_SOC_DAIFMT_NB_NF):
+		/* No delay after the frame sync */
+		serial_format = TAS5720_SAIF_LEFTJ;
+		break;
+	default:
+		dev_vdbg(codec->dev, "DAI Format is not found\n");
+		return -EINVAL;
+	}
+
+	ret = snd_soc_update_bits(codec, TAS5720_DIGITAL_CTRL1_REG,
+				  TAS5720_SAIF_FORMAT_MASK,
+				  serial_format);
+	if (ret < 0) {
+		dev_err(codec->dev, "error setting SAIF format: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int tas5720_set_dai_tdm_slot(struct snd_soc_dai *dai,
+				    unsigned int tx_mask, unsigned int rx_mask,
+				    int slots, int slot_width)
+{
+	struct snd_soc_codec *codec = dai->codec;
+	unsigned int first_slot;
+	int ret;
+
+	if (!tx_mask) {
+		dev_err(codec->dev, "tx masks must not be 0\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Determine the first slot that is being requested. We will only
+	 * use the first slot that is found since the TAS5720 is a mono
+	 * amplifier.
+	 */
+	first_slot = __ffs(tx_mask);
+
+	if (first_slot > 7) {
+		dev_err(codec->dev, "slot selection out of bounds (%u)\n",
+			first_slot);
+		return -EINVAL;
+	}
+
+	/* Enable manual TDM slot selection (instead of I2C ID based) */
+	ret = snd_soc_update_bits(codec, TAS5720_DIGITAL_CTRL1_REG,
+				  TAS5720_TDM_CFG_SRC, TAS5720_TDM_CFG_SRC);
+	if (ret < 0)
+		goto error_snd_soc_update_bits;
+
+	/* Configure the TDM slot to process audio from */
+	ret = snd_soc_update_bits(codec, TAS5720_DIGITAL_CTRL2_REG,
+				  TAS5720_TDM_SLOT_SEL_MASK, first_slot);
+	if (ret < 0)
+		goto error_snd_soc_update_bits;
+
+	return 0;
+
+error_snd_soc_update_bits:
+	dev_err(codec->dev, "error configuring TDM mode: %d\n", ret);
+	return ret;
+}
+
+static int tas5720_mute(struct snd_soc_dai *dai, int mute)
+{
+	struct snd_soc_codec *codec = dai->codec;
+	int ret;
+
+	ret = snd_soc_update_bits(codec, TAS5720_DIGITAL_CTRL2_REG,
+				  TAS5720_MUTE, mute ? TAS5720_MUTE : 0);
+	if (ret < 0) {
+		dev_err(codec->dev, "error (un-)muting device: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void tas5720_fault_check_work(struct work_struct *work)
+{
+	struct tas5720_data *tas5720 = container_of(work, struct tas5720_data,
+			fault_check_work.work);
+	struct device *dev = tas5720->codec->dev;
+	unsigned int curr_fault;
+	int ret;
+
+	ret = regmap_read(tas5720->regmap, TAS5720_FAULT_REG, &curr_fault);
+	if (ret < 0) {
+		dev_err(dev, "failed to read FAULT register: %d\n", ret);
+		goto out;
+	}
+
+	/* Check/handle all errors except SAIF clock errors */
+	curr_fault &= TAS5720_OCE | TAS5720_DCE | TAS5720_OTE;
+
+	/*
+	 * Only flag errors once for a given occurrence. This is needed as
+	 * the TAS5720 will take time clearing the fault condition internally
+	 * during which we don't want to bombard the system with the same
+	 * error message over and over.
+	 */
+	if ((curr_fault & TAS5720_OCE) && !(tas5720->last_fault & TAS5720_OCE))
+		dev_crit(dev, "experienced an over current hardware fault\n");
+
+	if ((curr_fault & TAS5720_DCE) && !(tas5720->last_fault & TAS5720_DCE))
+		dev_crit(dev, "experienced a DC detection fault\n");
+
+	if ((curr_fault & TAS5720_OTE) && !(tas5720->last_fault & TAS5720_OTE))
+		dev_crit(dev, "experienced an over temperature fault\n");
+
+	/* Store current fault value so we can detect any changes next time */
+	tas5720->last_fault = curr_fault;
+
+	if (!curr_fault)
+		goto out;
+
+	/*
+	 * Periodically toggle SDZ (shutdown bit) H->L->H to clear any latching
+	 * faults as long as a fault condition persists. Always going through
+	 * the full sequence no matter the first return value to minimizes
+	 * chances for the device to end up in shutdown mode.
+	 */
+	ret = regmap_write_bits(tas5720->regmap, TAS5720_POWER_CTRL_REG,
+				TAS5720_SDZ, 0);
+	if (ret < 0)
+		dev_err(dev, "failed to write POWER_CTRL register: %d\n", ret);
+
+	ret = regmap_write_bits(tas5720->regmap, TAS5720_POWER_CTRL_REG,
+				TAS5720_SDZ, TAS5720_SDZ);
+	if (ret < 0)
+		dev_err(dev, "failed to write POWER_CTRL register: %d\n", ret);
+
+out:
+	/* Schedule the next fault check at the specified interval */
+	schedule_delayed_work(&tas5720->fault_check_work,
+			      msecs_to_jiffies(TAS5720_FAULT_CHECK_INTERVAL));
+}
+
+static int tas5720_codec_probe(struct snd_soc_codec *codec)
+{
+	struct tas5720_data *tas5720 = snd_soc_codec_get_drvdata(codec);
+	unsigned int device_id;
+	int ret;
+
+	tas5720->codec = codec;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(tas5720->supplies),
+				    tas5720->supplies);
+	if (ret != 0) {
+		dev_err(codec->dev, "failed to enable supplies: %d\n", ret);
+		return ret;
+	}
+
+	ret = regmap_read(tas5720->regmap, TAS5720_DEVICE_ID_REG, &device_id);
+	if (ret < 0) {
+		dev_err(codec->dev, "failed to read device ID register: %d\n",
+			ret);
+		goto probe_fail;
+	}
+
+	if (device_id != TAS5720_DEVICE_ID) {
+		dev_err(codec->dev, "wrong device ID. expected: %u read: %u\n",
+			TAS5720_DEVICE_ID, device_id);
+		ret = -ENODEV;
+		goto probe_fail;
+	}
+
+	/* Set device to mute */
+	ret = snd_soc_update_bits(codec, TAS5720_DIGITAL_CTRL2_REG,
+				  TAS5720_MUTE, TAS5720_MUTE);
+	if (ret < 0)
+		goto error_snd_soc_update_bits;
+
+	/*
+	 * Enter shutdown mode - our default when not playing audio - to
+	 * minimize current consumption. On the TAS5720 there is no real down
+	 * side doing so as all device registers are preserved and the wakeup
+	 * of the codec is rather quick which we do using a dapm widget.
+	 */
+	ret = snd_soc_update_bits(codec, TAS5720_POWER_CTRL_REG,
+				  TAS5720_SDZ, 0);
+	if (ret < 0)
+		goto error_snd_soc_update_bits;
+
+	INIT_DELAYED_WORK(&tas5720->fault_check_work, tas5720_fault_check_work);
+
+	return 0;
+
+error_snd_soc_update_bits:
+	dev_err(codec->dev, "error configuring device registers: %d\n", ret);
+
+probe_fail:
+	regulator_bulk_disable(ARRAY_SIZE(tas5720->supplies),
+			       tas5720->supplies);
+	return ret;
+}
+
+static int tas5720_codec_remove(struct snd_soc_codec *codec)
+{
+	struct tas5720_data *tas5720 = snd_soc_codec_get_drvdata(codec);
+	int ret;
+
+	cancel_delayed_work_sync(&tas5720->fault_check_work);
+
+	ret = regulator_bulk_disable(ARRAY_SIZE(tas5720->supplies),
+				     tas5720->supplies);
+	if (ret < 0)
+		dev_err(codec->dev, "failed to disable supplies: %d\n", ret);
+
+	return ret;
+};
+
+static int tas5720_dac_event(struct snd_soc_dapm_widget *w,
+			     struct snd_kcontrol *kcontrol, int event)
+{
+	struct snd_soc_codec *codec = snd_soc_dapm_to_codec(w->dapm);
+	struct tas5720_data *tas5720 = snd_soc_codec_get_drvdata(codec);
+	int ret;
+
+	if (event & SND_SOC_DAPM_POST_PMU) {
+		/* Take TAS5720 out of shutdown mode */
+		ret = snd_soc_update_bits(codec, TAS5720_POWER_CTRL_REG,
+					  TAS5720_SDZ, TAS5720_SDZ);
+		if (ret < 0) {
+			dev_err(codec->dev, "error waking codec: %d\n", ret);
+			return ret;
+		}
+
+		/*
+		 * Observe codec shutdown-to-active time. The datasheet only
+		 * lists a nominal value however just use-it as-is without
+		 * additional padding to minimize the delay introduced in
+		 * starting to play audio (actually there is other setup done
+		 * by the ASoC framework that will provide additional delays,
+		 * so we should always be safe).
+		 */
+		msleep(25);
+
+		/* Turn on TAS5720 periodic fault checking/handling */
+		tas5720->last_fault = 0;
+		schedule_delayed_work(&tas5720->fault_check_work,
+				msecs_to_jiffies(TAS5720_FAULT_CHECK_INTERVAL));
+	} else if (event & SND_SOC_DAPM_PRE_PMD) {
+		/* Disable TAS5720 periodic fault checking/handling */
+		cancel_delayed_work_sync(&tas5720->fault_check_work);
+
+		/* Place TAS5720 in shutdown mode to minimize current draw */
+		ret = snd_soc_update_bits(codec, TAS5720_POWER_CTRL_REG,
+					  TAS5720_SDZ, 0);
+		if (ret < 0) {
+			dev_err(codec->dev, "error shutting down codec: %d\n",
+				ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int tas5720_suspend(struct snd_soc_codec *codec)
+{
+	struct tas5720_data *tas5720 = snd_soc_codec_get_drvdata(codec);
+	int ret;
+
+	regcache_cache_only(tas5720->regmap, true);
+	regcache_mark_dirty(tas5720->regmap);
+
+	ret = regulator_bulk_disable(ARRAY_SIZE(tas5720->supplies),
+				     tas5720->supplies);
+	if (ret < 0)
+		dev_err(codec->dev, "failed to disable supplies: %d\n", ret);
+
+	return ret;
+}
+
+static int tas5720_resume(struct snd_soc_codec *codec)
+{
+	struct tas5720_data *tas5720 = snd_soc_codec_get_drvdata(codec);
+	int ret;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(tas5720->supplies),
+				    tas5720->supplies);
+	if (ret < 0) {
+		dev_err(codec->dev, "failed to enable supplies: %d\n", ret);
+		return ret;
+	}
+
+	regcache_cache_only(tas5720->regmap, false);
+
+	ret = regcache_sync(tas5720->regmap);
+	if (ret < 0) {
+		dev_err(codec->dev, "failed to sync regcache: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+#else
+#define tas5720_suspend NULL
+#define tas5720_resume NULL
+#endif
+
+static bool tas5720_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case TAS5720_DEVICE_ID_REG:
+	case TAS5720_FAULT_REG:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config tas5720_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.max_register = TAS5720_MAX_REG,
+	.cache_type = REGCACHE_RBTREE,
+	.volatile_reg = tas5720_is_volatile_reg,
+};
+
+/*
+ * DAC analog gain. There are four discrete values to select from, ranging
+ * from 19.2 dB to 26.3dB.
+ */
+static const DECLARE_TLV_DB_RANGE(dac_analog_tlv,
+	0x0, 0x0, TLV_DB_SCALE_ITEM(1920, 0, 0),
+	0x1, 0x1, TLV_DB_SCALE_ITEM(2070, 0, 0),
+	0x2, 0x2, TLV_DB_SCALE_ITEM(2350, 0, 0),
+	0x3, 0x3, TLV_DB_SCALE_ITEM(2630, 0, 0),
+);
+
+/*
+ * DAC digital volumes. From -103.5 to 24 dB in 0.5 dB steps. Note that
+ * setting the gain below -100 dB (register value <0x7) is effectively a MUTE
+ * as per device datasheet.
+ */
+static DECLARE_TLV_DB_SCALE(dac_tlv, -10350, 50, 0);
+
+static const struct snd_kcontrol_new tas5720_snd_controls[] = {
+	SOC_SINGLE_TLV("Speaker Driver Playback Volume",
+		       TAS5720_VOLUME_CTRL_REG, 0, 0xff, 0, dac_tlv),
+	SOC_SINGLE_TLV("Speaker Driver Analog Gain", TAS5720_ANALOG_CTRL_REG,
+		       TAS5720_ANALOG_GAIN_SHIFT, 3, 0, dac_analog_tlv),
+};
+
+static const struct snd_soc_dapm_widget tas5720_dapm_widgets[] = {
+	SND_SOC_DAPM_AIF_IN("DAC IN", "Playback", 0, SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_DAC_E("DAC", NULL, SND_SOC_NOPM, 0, 0, tas5720_dac_event,
+			   SND_SOC_DAPM_POST_PMU | SND_SOC_DAPM_PRE_PMD),
+	SND_SOC_DAPM_OUTPUT("OUT")
+};
+
+static const struct snd_soc_dapm_route tas5720_audio_map[] = {
+	{ "DAC", NULL, "DAC IN" },
+	{ "OUT", NULL, "DAC" },
+};
+
+static struct snd_soc_codec_driver soc_codec_dev_tas5720 = {
+	.probe = tas5720_codec_probe,
+	.remove = tas5720_codec_remove,
+	.suspend = tas5720_suspend,
+	.resume = tas5720_resume,
+
+	.controls = tas5720_snd_controls,
+	.num_controls = ARRAY_SIZE(tas5720_snd_controls),
+	.dapm_widgets = tas5720_dapm_widgets,
+	.num_dapm_widgets = ARRAY_SIZE(tas5720_dapm_widgets),
+	.dapm_routes = tas5720_audio_map,
+	.num_dapm_routes = ARRAY_SIZE(tas5720_audio_map),
+};
+
+/* PCM rates supported by the TAS5720 driver */
+#define TAS5720_RATES	(SNDRV_PCM_RATE_44100 | SNDRV_PCM_RATE_48000 |\
+			 SNDRV_PCM_RATE_88200 | SNDRV_PCM_RATE_96000)
+
+/* Formats supported by TAS5720 driver */
+#define TAS5720_FORMATS (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S18_3LE |\
+			 SNDRV_PCM_FMTBIT_S20_3LE | SNDRV_PCM_FMTBIT_S24_LE)
+
+static struct snd_soc_dai_ops tas5720_speaker_dai_ops = {
+	.hw_params	= tas5720_hw_params,
+	.set_fmt	= tas5720_set_dai_fmt,
+	.set_tdm_slot	= tas5720_set_dai_tdm_slot,
+	.digital_mute	= tas5720_mute,
+};
+
+/*
+ * TAS5720 DAI structure
+ *
+ * Note that were are advertising .playback.channels_max = 2 despite this being
+ * a mono amplifier. The reason for that is that some serial ports such as TI's
+ * McASP module have a minimum number of channels (2) that they can output.
+ * Advertising more channels than we have will allow us to interface with such
+ * a serial port without really any negative side effects as the TAS5720 will
+ * simply ignore any extra channel(s) asides from the one channel that is
+ * configured to be played back.
+ */
+static struct snd_soc_dai_driver tas5720_dai[] = {
+	{
+		.name = "tas5720-amplifier",
+		.playback = {
+			.stream_name = "Playback",
+			.channels_min = 1,
+			.channels_max = 2,
+			.rates = TAS5720_RATES,
+			.formats = TAS5720_FORMATS,
+		},
+		.ops = &tas5720_speaker_dai_ops,
+	},
+};
+
+static int tas5720_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct tas5720_data *data;
+	int ret;
+	int i;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->tas5720_client = client;
+	data->regmap = devm_regmap_init_i2c(client, &tas5720_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		ret = PTR_ERR(data->regmap);
+		dev_err(dev, "failed to allocate register map: %d\n", ret);
+		return ret;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(data->supplies); i++)
+		data->supplies[i].supply = tas5720_supply_names[i];
+
+	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(data->supplies),
+				      data->supplies);
+	if (ret != 0) {
+		dev_err(dev, "failed to request supplies: %d\n", ret);
+		return ret;
+	}
+
+	dev_set_drvdata(dev, data);
+
+	ret = snd_soc_register_codec(&client->dev,
+				     &soc_codec_dev_tas5720,
+				     tas5720_dai, ARRAY_SIZE(tas5720_dai));
+	if (ret < 0) {
+		dev_err(dev, "failed to register codec: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int tas5720_remove(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+
+	snd_soc_unregister_codec(dev);
+
+	return 0;
+}
+
+static const struct i2c_device_id tas5720_id[] = {
+	{ "tas5720", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tas5720_id);
+
+#if IS_ENABLED(CONFIG_OF)
+static const struct of_device_id tas5720_of_match[] = {
+	{ .compatible = "ti,tas5720", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, tas5720_of_match);
+#endif
+
+static struct i2c_driver tas5720_i2c_driver = {
+	.driver = {
+		.name = "tas5720",
+		.of_match_table = of_match_ptr(tas5720_of_match),
+	},
+	.probe = tas5720_probe,
+	.remove = tas5720_remove,
+	.id_table = tas5720_id,
+};
+
+module_i2c_driver(tas5720_i2c_driver);
+
+MODULE_AUTHOR("Andreas Dannenberg <dannenberg@ti.com>");
+MODULE_DESCRIPTION("TAS5720 Audio amplifier driver");
+MODULE_LICENSE("GPL");