ASoC: ssm3515: Add new amp driver

The Analog Devices' SSM3515 is a mono audio amplifier with digital
input, equipped on Apple's 2021 iMacs. Add an ASoC driver for it, and
register both the driver code and schema in MAINTAINERS.

Signed-off-by: Martin Povišer <povik+lin@cutebit.org
Link: https://lore.kernel.org/r/20230511150546.8499-3-povik+lin@cutebit.org
Signed-off-by: Mark Brown <broonie@kernel.org

MAINTAINERS

@@ -1990,9 +1990,11 @@ M:	Martin Povišer <povik+lin@cutebit.org>
 L:	asahi@lists.linux.dev
 L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
 S:	Maintained
+F:	Documentation/devicetree/bindings/sound/adi,ssm3515.yaml
 F:	Documentation/devicetree/bindings/sound/apple,*
 F:	sound/soc/apple/*
 F:	sound/soc/codecs/cs42l83-i2c.c
+F:	sound/soc/codecs/ssm3515.c
 
 ARM/ARTPEC MACHINE SUPPORT
 M:	Jesper Nilsson <jesper.nilsson@axis.com>

sound/soc/codecs/Kconfig

@@ -1659,6 +1659,12 @@ config SND_SOC_SSM2602_I2C
 	select SND_SOC_SSM2602
 	select REGMAP_I2C
 
+config SND_SOC_SSM3515
+	tristate "Analog Devices SSM3515 amplifier driver"
+	select REGMAP_I2C
+	depends on I2C
+	depends on OF
+
 config SND_SOC_SSM4567
 	tristate "Analog Devices ssm4567 amplifier driver support"
 	depends on I2C

sound/soc/codecs/Makefile

@@ -257,6 +257,7 @@ snd-soc-ssm2518-objs := ssm2518.o
 snd-soc-ssm2602-objs := ssm2602.o
 snd-soc-ssm2602-spi-objs := ssm2602-spi.o
 snd-soc-ssm2602-i2c-objs := ssm2602-i2c.o
+snd-soc-ssm3515-objs := ssm3515.o
 snd-soc-ssm4567-objs := ssm4567.o
 snd-soc-sta32x-objs := sta32x.o
 snd-soc-sta350-objs := sta350.o
@@ -625,6 +626,7 @@ obj-$(CONFIG_SND_SOC_SSM2518)	+= snd-soc-ssm2518.o
 obj-$(CONFIG_SND_SOC_SSM2602)	+= snd-soc-ssm2602.o
 obj-$(CONFIG_SND_SOC_SSM2602_SPI)	+= snd-soc-ssm2602-spi.o
 obj-$(CONFIG_SND_SOC_SSM2602_I2C)	+= snd-soc-ssm2602-i2c.o
+obj-$(CONFIG_SND_SOC_SSM3515)	+= snd-soc-ssm3515.o
 obj-$(CONFIG_SND_SOC_SSM4567)	+= snd-soc-ssm4567.o
 obj-$(CONFIG_SND_SOC_STA32X)   += snd-soc-sta32x.o
 obj-$(CONFIG_SND_SOC_STA350)   += snd-soc-sta350.o

sound/soc/codecs/ssm3515.c

+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+//
+// Analog Devices' SSM3515 audio amp driver
+//
+// Copyright (C) The Asahi Linux Contributors
+
+#include <linux/bits.h>
+#include <linux/bitfield.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/tlv.h>
+
+
+#define SSM3515_PWR		0x00
+#define SSM3515_PWR_APWDN_EN	BIT(7)
+#define SSM3515_PWR_BSNS_PWDN	BIT(6)
+#define SSM3515_PWR_S_RST	BIT(1)
+#define SSM3515_PWR_SPWDN	BIT(0)
+
+#define SSM3515_GEC		0x01
+#define SSM3515_GEC_EDGE	BIT(4)
+#define SSM3515_GEC_EDGE_SHIFT	4
+#define SSM3515_GEC_ANA_GAIN	GENMASK(1, 0)
+
+#define SSM3515_DAC		0x02
+#define SSM3515_DAC_HV		BIT(7)
+#define SSM3515_DAC_MUTE	BIT(6)
+#define SSM3515_DAC_HPF		BIT(5)
+#define SSM3515_DAC_LPM		BIT(4)
+#define SSM3515_DAC_FS		GENMASK(2, 0)
+
+#define SSM3515_DAC_VOL		0x03
+
+#define SSM3515_SAI1		0x04
+#define SSM3515_SAI1_DAC_POL	BIT(7)
+#define SSM3515_SAI1_BCLK_POL	BIT(6)
+#define SSM3515_SAI1_TDM_BCLKS	GENMASK(5, 3)
+#define SSM3515_SAI1_FSYNC_MODE	BIT(2)
+#define SSM3515_SAI1_SDATA_FMT	BIT(1)
+#define SSM3515_SAI1_SAI_MODE	BIT(0)
+
+#define SSM3515_SAI2		0x05
+#define SSM3515_SAI2_DATA_WIDTH	BIT(7)
+#define SSM3515_SAI2_AUTO_SLOT	BIT(4)
+#define SSM3515_SAI2_TDM_SLOT	GENMASK(3, 0)
+
+#define SSM3515_VBAT_OUT	0x06
+
+#define SSM3515_STATUS		0x0a
+#define SSM3515_STATUS_UVLO_REG	BIT(6)
+#define SSM3515_STATUS_LIM_EG	BIT(5)
+#define SSM3515_STATUS_CLIP	BIT(4)
+#define SSM3515_STATUS_AMP_OC	BIT(3)
+#define SSM3515_STATUS_OTF	BIT(2)
+#define SSM3515_STATUS_OTW	BIT(1)
+#define SSM3515_STATUS_BAT_WARN	BIT(0)
+
+static bool ssm3515_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case SSM3515_STATUS:
+	case SSM3515_VBAT_OUT:
+		return true;
+
+	default:
+		return false;
+	}
+}
+
+static const struct reg_default ssm3515_reg_defaults[] = {
+	{ SSM3515_PWR, 0x81 },
+	{ SSM3515_GEC, 0x01 },
+	{ SSM3515_DAC, 0x32 },
+	{ SSM3515_DAC_VOL, 0x40 },
+	{ SSM3515_SAI1, 0x11 },
+	{ SSM3515_SAI2, 0x00 },
+};
+
+static const struct regmap_config ssm3515_i2c_regmap = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.volatile_reg = ssm3515_volatile_reg,
+	.max_register = 0xb,
+	.reg_defaults = ssm3515_reg_defaults,
+	.num_reg_defaults = ARRAY_SIZE(ssm3515_reg_defaults),
+	.cache_type = REGCACHE_FLAT,
+};
+
+struct ssm3515_data {
+	struct device *dev;
+	struct regmap *regmap;
+};
+
+// The specced range is -71.25...24.00 dB with step size of 0.375 dB,
+// and a mute item below that. This is represented by -71.62...24.00 dB
+// with the mute item mapped onto the low end.
+static DECLARE_TLV_DB_MINMAX_MUTE(ssm3515_dac_volume, -7162, 2400);
+
+static const char * const ssm3515_ana_gain_text[] = {
+	"8.4 V Span", "12.6 V Span", "14 V Span", "15 V Span",
+};
+
+static SOC_ENUM_SINGLE_DECL(ssm3515_ana_gain_enum, SSM3515_GEC,
+			    __bf_shf(SSM3515_GEC_ANA_GAIN),
+			    ssm3515_ana_gain_text);
+
+static const struct snd_kcontrol_new ssm3515_snd_controls[] = {
+	SOC_SINGLE_TLV("DAC Playback Volume", SSM3515_DAC_VOL,
+		       0, 255, 1, ssm3515_dac_volume),
+	SOC_SINGLE("Low EMI Mode Switch", SSM3515_GEC,
+		   __bf_shf(SSM3515_GEC_EDGE), 1, 0),
+	SOC_SINGLE("Soft Volume Ramping Switch", SSM3515_DAC,
+		   __bf_shf(SSM3515_DAC_HV), 1, 1),
+	SOC_SINGLE("HPF Switch", SSM3515_DAC,
+		   __bf_shf(SSM3515_DAC_HPF), 1, 0),
+	SOC_SINGLE("DAC Invert Switch", SSM3515_SAI1,
+		   __bf_shf(SSM3515_SAI1_DAC_POL), 1, 0),
+	SOC_ENUM("DAC Analog Gain Select", ssm3515_ana_gain_enum),
+};
+
+static void ssm3515_read_faults(struct snd_soc_component *component)
+{
+	int ret;
+
+	ret = snd_soc_component_read(component, SSM3515_STATUS);
+	if (ret <= 0) {
+		/*
+		 * If the read was erroneous, ASoC core has printed a message,
+		 * and that's all that's appropriate in handling the error here.
+		 */
+		return;
+	}
+
+	dev_err(component->dev, "device reports:%s%s%s%s%s%s%s\n",
+		FIELD_GET(SSM3515_STATUS_UVLO_REG, ret) ? " voltage regulator fault" : "",
+		FIELD_GET(SSM3515_STATUS_LIM_EG, ret)   ? " limiter engaged" : "",
+		FIELD_GET(SSM3515_STATUS_CLIP, ret)     ? " clipping detected" : "",
+		FIELD_GET(SSM3515_STATUS_AMP_OC, ret)   ? " amp over-current fault" : "",
+		FIELD_GET(SSM3515_STATUS_OTF, ret)      ? " overtemperature fault" : "",
+		FIELD_GET(SSM3515_STATUS_OTW, ret)      ? " overtemperature warning" : "",
+		FIELD_GET(SSM3515_STATUS_BAT_WARN, ret) ? " bat voltage low warning" : "");
+}
+
+static int ssm3515_probe(struct snd_soc_component *component)
+{
+	int ret;
+
+	/* Start out muted */
+	ret = snd_soc_component_update_bits(component, SSM3515_DAC,
+			SSM3515_DAC_MUTE, SSM3515_DAC_MUTE);
+	if (ret < 0)
+		return ret;
+
+	/* Disable the 'master power-down' */
+	ret = snd_soc_component_update_bits(component, SSM3515_PWR,
+			SSM3515_PWR_SPWDN, 0);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int ssm3515_mute(struct snd_soc_dai *dai, int mute, int direction)
+{
+	int ret;
+
+	ret = snd_soc_component_update_bits(dai->component,
+					    SSM3515_DAC,
+					    SSM3515_DAC_MUTE,
+					    FIELD_PREP(SSM3515_DAC_MUTE, mute));
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+static int ssm3515_hw_params(struct snd_pcm_substream *substream,
+			     struct snd_pcm_hw_params *params,
+			     struct snd_soc_dai *dai)
+{
+	struct snd_soc_component *component = dai->component;
+	int ret, rateval;
+
+	switch (params_format(params)) {
+	case SNDRV_PCM_FORMAT_S16:
+	case SNDRV_PCM_FORMAT_S24:
+		ret = snd_soc_component_update_bits(component,
+				SSM3515_SAI2, SSM3515_SAI2_DATA_WIDTH,
+				FIELD_PREP(SSM3515_SAI2_DATA_WIDTH,
+					   params_width(params) == 16));
+		if (ret < 0)
+			return ret;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	switch (params_rate(params)) {
+	case 8000 ... 12000:
+		rateval = 0;
+		break;
+	case 16000 ... 24000:
+		rateval = 1;
+		break;
+	case 32000 ... 48000:
+		rateval = 2;
+		break;
+	case 64000 ... 96000:
+		rateval = 3;
+		break;
+	case 128000 ... 192000:
+		rateval = 4;
+		break;
+	case 48001 ... 63999: /* this is ...72000 but overlaps */
+		rateval = 5;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = snd_soc_component_update_bits(component,
+			SSM3515_DAC, SSM3515_DAC_FS,
+			FIELD_PREP(SSM3515_DAC_FS, rateval));
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int ssm3515_set_fmt(struct snd_soc_dai *dai, unsigned int fmt)
+{
+	struct snd_soc_component *component = dai->component;
+	bool fpol_inv = false; /* non-inverted: frame starts with low-to-high FSYNC */
+	int ret;
+	u8 sai1 = 0;
+
+	switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
+	case SND_SOC_DAIFMT_IB_NF:
+	case SND_SOC_DAIFMT_IB_IF:
+		sai1 |= SSM3515_SAI1_BCLK_POL;
+		break;
+	}
+
+	switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
+	case SND_SOC_DAIFMT_I2S:
+		fpol_inv = 1;
+		sai1 &= ~SSM3515_SAI1_SDATA_FMT; /* 1 bit start delay */
+		break;
+	case SND_SOC_DAIFMT_LEFT_J:
+		fpol_inv = 0;
+		sai1 |= SSM3515_SAI1_SDATA_FMT; /* no start delay */
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
+	case SND_SOC_DAIFMT_NB_IF:
+	case SND_SOC_DAIFMT_IB_IF:
+		fpol_inv ^= 1;
+		break;
+	}
+
+	/* Set the serial input to 'TDM mode' */
+	sai1 |= SSM3515_SAI1_SAI_MODE;
+
+	if (fpol_inv) {
+		/*
+		 * We configure the codec in a 'TDM mode', in which the
+		 * FSYNC_MODE bit of SAI1 is supposed to select between
+		 * what the datasheet calls 'Pulsed FSYNC mode' and '50%
+		 * FSYNC mode'.
+		 *
+		 * Experiments suggest that this bit in fact simply selects
+		 * the FSYNC polarity, so go with that.
+		 */
+		sai1 |= SSM3515_SAI1_FSYNC_MODE;
+	}
+
+	ret = snd_soc_component_update_bits(component, SSM3515_SAI1,
+			SSM3515_SAI1_BCLK_POL | SSM3515_SAI1_SDATA_FMT |
+			SSM3515_SAI1_SAI_MODE | SSM3515_SAI1_FSYNC_MODE, sai1);
+
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+static int ssm3515_set_tdm_slot(struct snd_soc_dai *dai,
+				unsigned int tx_mask,
+				unsigned int rx_mask,
+				int slots, int slot_width)
+{
+	struct snd_soc_component *component = dai->component;
+	int slot, tdm_bclks_val, ret;
+
+	if (tx_mask == 0 || rx_mask != 0)
+		return -EINVAL;
+
+	slot = __ffs(tx_mask);
+
+	if (tx_mask & ~BIT(slot))
+		return -EINVAL;
+
+	switch (slot_width) {
+	case 16:
+		tdm_bclks_val = 0;
+		break;
+	case 24:
+		tdm_bclks_val = 1;
+		break;
+	case 32:
+		tdm_bclks_val = 2;
+		break;
+	case 48:
+		tdm_bclks_val = 3;
+		break;
+	case 64:
+		tdm_bclks_val = 4;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = snd_soc_component_update_bits(component, SSM3515_SAI1,
+			SSM3515_SAI1_TDM_BCLKS,
+			FIELD_PREP(SSM3515_SAI1_TDM_BCLKS, tdm_bclks_val));
+	if (ret < 0)
+		return ret;
+
+	ret = snd_soc_component_update_bits(component, SSM3515_SAI2,
+			SSM3515_SAI2_TDM_SLOT,
+			FIELD_PREP(SSM3515_SAI2_TDM_SLOT, slot));
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int ssm3515_hw_free(struct snd_pcm_substream *substream,
+			   struct snd_soc_dai *dai)
+{
+	/*
+	 * We don't get live notification of faults, so at least at
+	 * this time, when playback is over, check if we have tripped
+	 * over anything and if so, log it.
+	 */
+	ssm3515_read_faults(dai->component);
+	return 0;
+}
+
+static const struct snd_soc_dai_ops ssm3515_dai_ops = {
+	.mute_stream	= ssm3515_mute,
+	.hw_params	= ssm3515_hw_params,
+	.set_fmt	= ssm3515_set_fmt,
+	.set_tdm_slot	= ssm3515_set_tdm_slot,
+	.hw_free	= ssm3515_hw_free,
+};
+
+static struct snd_soc_dai_driver ssm3515_dai_driver = {
+	.name = "SSM3515 SAI",
+	.id = 0,
+	.playback = {
+		.stream_name = "Playback",
+		.channels_min = 1,
+		.channels_max = 1,
+		.rates = SNDRV_PCM_RATE_CONTINUOUS,
+		.formats = SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S24_LE,
+	},
+	.ops = &ssm3515_dai_ops,
+};
+
+static const struct snd_soc_dapm_widget ssm3515_dapm_widgets[] = {
+	SND_SOC_DAPM_DAC("DAC", NULL, SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_OUTPUT("OUT"),
+};
+
+static const struct snd_soc_dapm_route ssm3515_dapm_routes[] = {
+	{"OUT", NULL, "DAC"},
+	{"DAC", NULL, "Playback"},
+};
+
+static const struct snd_soc_component_driver ssm3515_asoc_component = {
+	.probe = ssm3515_probe,
+	.controls = ssm3515_snd_controls,
+	.num_controls = ARRAY_SIZE(ssm3515_snd_controls),
+	.dapm_widgets = ssm3515_dapm_widgets,
+	.num_dapm_widgets = ARRAY_SIZE(ssm3515_dapm_widgets),
+	.dapm_routes = ssm3515_dapm_routes,
+	.num_dapm_routes = ARRAY_SIZE(ssm3515_dapm_routes),
+	.endianness = 1,
+};
+
+static int ssm3515_i2c_probe(struct i2c_client *client)
+{
+	struct ssm3515_data *data;
+	int ret;
+
+	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->dev = &client->dev;
+	i2c_set_clientdata(client, data);
+
+	data->regmap = devm_regmap_init_i2c(client, &ssm3515_i2c_regmap);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(data->dev, PTR_ERR(data->regmap),
+				     "initializing register map\n");
+
+	/* Perform a reset */
+	ret = regmap_update_bits(data->regmap, SSM3515_PWR,
+			SSM3515_PWR_S_RST, SSM3515_PWR_S_RST);
+	if (ret < 0)
+		return dev_err_probe(data->dev, ret,
+				     "performing software reset\n");
+	regmap_reinit_cache(data->regmap, &ssm3515_i2c_regmap);
+
+	return devm_snd_soc_register_component(data->dev,
+			&ssm3515_asoc_component,
+			&ssm3515_dai_driver, 1);
+}
+
+static const struct of_device_id ssm3515_of_match[] = {
+	{ .compatible = "adi,ssm3515" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ssm3515_of_match);
+
+static struct i2c_driver ssm3515_i2c_driver = {
+	.driver = {
+		.name = "ssm3515",
+		.of_match_table = of_match_ptr(ssm3515_of_match),
+	},
+	.probe_new = ssm3515_i2c_probe,
+};
+module_i2c_driver(ssm3515_i2c_driver);
+
+MODULE_AUTHOR("Martin Povišer <povik+lin@cutebit.org>");
+MODULE_DESCRIPTION("ASoC SSM3515 audio amp driver");
+MODULE_LICENSE("Dual MIT/GPL");