audio: codec: Add driver for MAX98091 codec

This patch adds a minimal driver for the MAX98091 audio codec.
Currently, playback functionality is supported.

Co-developed-by: Rutvij Trivedi <rutvij.trivedi@siliconsignals.io>
Signed-off-by: Rutvij Trivedi <rutvij.trivedi@siliconsignals.io>
Co-developed-by: Tarang Raval <tarang.raval@siliconsignals.io>
Signed-off-by: Tarang Raval <tarang.raval@siliconsignals.io>
Signed-off-by: Silicon Signals <siliconsignalsforgit@gmail.com>

Author: Silicon-Signals

drivers/audio/CMakeLists.txt

@@ -14,3 +14,4 @@ zephyr_library_sources_ifdef(CONFIG_AUDIO_CODEC_WM8904 wm8904.c)
 zephyr_library_sources_ifdef(CONFIG_AUDIO_CODEC_WM8962 wm8962.c)
 zephyr_library_sources_ifdef(CONFIG_AUDIO_CODEC_CS43L22 cs43l22.c)
 zephyr_library_sources_ifdef(CONFIG_AUDIO_CODEC_PCM1681 pcm1681.c)
+zephyr_library_sources_ifdef(CONFIG_AUDIO_CODEC_MAX98091 max98091.c)

drivers/audio/Kconfig

@@ -36,6 +36,7 @@ module-str = audio codec
 source "subsys/logging/Kconfig.template.log_config"
 
 source "drivers/audio/Kconfig.cs43l22"
+source "drivers/audio/Kconfig.max98091"
 source "drivers/audio/Kconfig.pcm1681"
 source "drivers/audio/Kconfig.tas6422dac"
 source "drivers/audio/Kconfig.tlv320aic3110"

drivers/audio/Kconfig.max98091

@@ -0,0 +1,10 @@
+# Copyright (c) 2025 Silicon Signals Pvt. Ltd.
+# SPDX-License-Identifier: Apache-2.0
+
+config AUDIO_CODEC_MAX98091
+	bool "Maxim MAX98091 codec support"
+	default y
+	select I2C
+	depends on DT_HAS_MAXIM_MAX98091_ENABLED
+	help
+	  Enable support for the MAX98091 I2S codec via I2C.

drivers/audio/max98091.c

@@ -0,0 +1,326 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Copyright (c) 2025 Silicon Signals Pvt. Ltd.
+ * Author: Rutvij Trivedi <rutvij.trivedi@siliconsignals.io>
+ * Author: Tarang Raval <tarang.raval@siliconsignals.io>
+ */
+
+#include <zephyr/drivers/i2c.h>
+#include <zephyr/audio/codec.h>
+#include <zephyr/device.h>
+#include <zephyr/logging/log.h>
+#include "max98091.h"
+
+LOG_MODULE_REGISTER(maxim_max98091);
+
+#define DT_DRV_COMPAT maxim_max98091
+
+struct max98091_config {
+	struct i2c_dt_spec i2c;
+	uint32_t mclk_freq;
+};
+
+static void max98091_write_reg(const struct device *dev, uint8_t reg, uint8_t val)
+{
+	const struct max98091_config *const dev_cfg = dev->config;
+
+	i2c_reg_write_byte_dt(&dev_cfg->i2c, reg, val);
+}
+
+static void max98091_read_reg(const struct device *dev, uint8_t reg, uint8_t *val)
+{
+	const struct max98091_config *const dev_cfg = dev->config;
+
+	i2c_reg_read_byte_dt(&dev_cfg->i2c, reg, val);
+}
+
+static void max98091_update_reg(const struct device *dev, uint8_t reg, uint8_t mask, uint8_t val)
+{
+	const struct max98091_config *const dev_cfg = dev->config;
+
+	i2c_reg_update_byte_dt(&dev_cfg->i2c, reg, mask, val);
+}
+
+static void max98091_soft_reset(const struct device *dev)
+{
+	max98091_write_reg(dev, M98091_REG_SOFTWARE_RESET, 0x01);
+	k_msleep(20);
+}
+
+/* Configuration Functions */
+static int max98091_protocol_config(const struct device *dev, audio_dai_type_t dai_type)
+{
+	uint8_t fmt_reg = 0;
+
+	switch (dai_type) {
+	case AUDIO_DAI_TYPE_I2S:
+		fmt_reg |= M98091_I2S_S_MASK;
+		break;
+	case AUDIO_DAI_TYPE_LEFT_JUSTIFIED:
+		fmt_reg |= M98091_LJ_S_MASK;
+		break;
+	case AUDIO_DAI_TYPE_RIGHT_JUSTIFIED:
+		fmt_reg |= M98091_RJ_S_MASK;
+		break;
+	default:
+		LOG_ERR("Unsupported DAI type: %d", dai_type);
+		return -EINVAL;
+	}
+	max98091_write_reg(dev, M98091_REG_DAI_INTERFACE, fmt_reg);
+	LOG_DBG("Protocol configured: 0x%02x", fmt_reg);
+	return 0;
+}
+
+static int max98091_audio_fmt_config(const struct device *dev, audio_dai_cfg_t *cfg)
+{
+	uint8_t sample_rate;
+	uint8_t channels;
+	uint8_t word_size;
+
+	switch (cfg->i2s.frame_clk_freq) {
+	case 8000:
+		sample_rate = M98091_SR_8K_MASK;
+		break;
+	case 16000:
+		sample_rate = M98091_SR_16K_MASK;
+		break;
+	case 32000:
+		sample_rate = M98091_SR_32K_MASK;
+		break;
+	case 44100:
+		sample_rate = M98091_SR_44K1_MASK;
+		break;
+	case 48000:
+		sample_rate = M98091_SR_48K_MASK;
+		break;
+	case 96000:
+		sample_rate = M98091_SR_96K_MASK;
+		break;
+	default:
+		LOG_ERR("Unsupported sample rate: %d", cfg->i2s.frame_clk_freq);
+		return -EINVAL;
+	}
+
+	max98091_write_reg(dev, M98091_REG_QUICK_SAMPLE_RATE, sample_rate);
+
+	switch (cfg->i2s.channels) {
+	case 1: /* Mono */
+		channels = 1;
+		break;
+	case 2: /* Stereo */
+		channels = 0;
+		break;
+	default:
+		LOG_ERR("Unsupported channels: %d", cfg->i2s.channels);
+		return -EINVAL;
+	}
+	max98091_update_reg(dev, M98091_REG_IO_CONFIGURATION, M98091_DMONO_MASK, channels);
+
+	switch (cfg->i2s.word_size) {
+	case 16:
+		word_size = M98091_16B_WS;
+		break;
+	default:
+		LOG_ERR("Word size %d bits not supported; falling back to 16 bits",
+			cfg->i2s.word_size);
+		word_size = M98091_16B_WS;
+		break;
+	}
+	max98091_update_reg(dev, M98091_REG_INTERFACE_FORMAT, M98091_WS_MASK, word_size);
+
+	return 0;
+}
+
+static void max98091_set_system_clock(const struct device *dev, uint32_t mclk_freq)
+{
+	uint8_t psclk;
+
+	if (mclk_freq >= 10000000 && mclk_freq <= 20000000) {
+		psclk = M98091_PSCLK_DIV1;
+	} else if (mclk_freq > 20000000 && mclk_freq <= 40000000) {
+		psclk = M98091_PSCLK_DIV2;
+	} else if (mclk_freq > 40000000 && mclk_freq <= 60000000) {
+		psclk = M98091_PSCLK_DIV4;
+	} else {
+		LOG_ERR("Invalid MCLK frequency: %u", mclk_freq);
+		return;
+	}
+	max98091_write_reg(dev, M98091_REG_SYSTEM_CLOCK, psclk);
+	LOG_DBG("System clock set: PSCLK=0x%02x", psclk);
+
+	max98091_update_reg(dev, M98091_REG_MASTER_MODE, M98091_MAS_MASK, 0);
+}
+
+static int max98091_set_volume_or_mute(const struct device *dev, audio_channel_t channel, int value,
+				      bool is_volume)
+{
+	uint8_t hp_mask = is_volume ? M98091_HPVOLL_MASK : M98091_HPLM_MASK;
+	uint8_t spk_mask = is_volume ? M98091_SPVOLL_MASK : M98091_SPLM_MASK;
+
+	switch (channel) {
+	case AUDIO_CHANNEL_FRONT_LEFT:
+		max98091_update_reg(dev, M98091_REG_LEFT_SPK_VOLUME, spk_mask, value);
+		return 0;
+
+	case AUDIO_CHANNEL_FRONT_RIGHT:
+		max98091_update_reg(dev, M98091_REG_RIGHT_SPK_VOLUME, spk_mask, value);
+		return 0;
+
+	case AUDIO_CHANNEL_HEADPHONE_LEFT:
+		max98091_update_reg(dev, M98091_REG_LEFT_HP_VOLUME, hp_mask, value);
+		return 0;
+
+	case AUDIO_CHANNEL_HEADPHONE_RIGHT:
+		max98091_update_reg(dev, M98091_REG_RIGHT_HP_VOLUME, hp_mask, value);
+		return 0;
+
+	case AUDIO_CHANNEL_ALL:
+		max98091_update_reg(dev, M98091_REG_LEFT_SPK_VOLUME, spk_mask, value);
+		max98091_update_reg(dev, M98091_REG_RIGHT_SPK_VOLUME, spk_mask, value);
+		max98091_update_reg(dev, M98091_REG_LEFT_HP_VOLUME, hp_mask, value);
+		max98091_update_reg(dev, M98091_REG_RIGHT_HP_VOLUME, hp_mask, value);
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int max98091_out_volume_config(const struct device *dev, audio_channel_t channel, int volume)
+{
+	return max98091_set_volume_or_mute(dev, channel, volume, true);
+}
+
+static int max98091_out_mute_config(const struct device *dev, audio_channel_t channel, bool mute)
+{
+	return max98091_set_volume_or_mute(dev, channel, mute, false);
+}
+
+/* Audio Path Configuration */
+static void max98091_configure_output(const struct device *dev)
+{
+	max98091_update_reg(dev, M98091_REG_IO_CONFIGURATION, M98091_SDIEN_MASK, M98091_SDIEN_MASK);
+
+	max98091_write_reg(dev, M98091_REG_LEFT_SPK_MIXER, M98091_MIXSPL_DACL_MASK);
+	max98091_write_reg(dev, M98091_REG_RIGHT_SPK_MIXER, M98091_MIXSPR_DACR_MASK);
+
+	/* select DAC only source */
+	max98091_write_reg(dev, M98091_REG_HP_CONTROL, 0x00);
+
+	/* M98091_HPREN_MASK, M98091_HPLEN_MASK, M98091_SPREN_MASK,
+	 * M98091_SPLEN_MASK, M98091_DAREN_MASK, M98091_DALEN_MASK
+	 */
+	max98091_write_reg(dev, M98091_REG_OUTPUT_ENABLE, 0xf3);
+
+	max98091_out_volume_config(dev, AUDIO_CHANNEL_ALL, M98091_DEFAULT_VOLUME);
+	max98091_out_mute_config(dev, AUDIO_CHANNEL_ALL, false);
+}
+
+static void max98091_start_output(const struct device *dev)
+{
+	ARG_UNUSED(dev);
+}
+
+static void max98091_stop_output(const struct device *dev)
+{
+	ARG_UNUSED(dev);
+}
+
+static int max98091_set_property(const struct device *dev, audio_property_t property,
+				 audio_channel_t channel, audio_property_value_t val)
+{
+	switch (property) {
+	case AUDIO_PROPERTY_OUTPUT_VOLUME:
+		max98091_out_volume_config(dev, channel, val.vol);
+	case AUDIO_PROPERTY_OUTPUT_MUTE:
+		max98091_out_mute_config(dev, channel, val.mute);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int max98091_configure(const struct device *dev, struct audio_codec_cfg *cfg)
+{
+	const struct max98091_config *const dev_cfg = dev->config;
+
+	if (cfg->dai_type >= AUDIO_DAI_TYPE_INVALID) {
+		LOG_ERR("dai_type not supported");
+		return -EINVAL;
+	}
+
+	max98091_soft_reset(dev);
+
+	if (cfg->dai_route == AUDIO_ROUTE_BYPASS) {
+		return 0;
+	}
+
+	/* Put the audio codec into shutdown mode */
+	max98091_write_reg(dev, M98091_REG_DEVICE_SHUTDOWN, 0x00);
+
+	max98091_write_reg(dev, M98091_REG_DAC_CONTROL, 0x00);
+
+	max98091_write_reg(dev, M98091_REG_TDM_CONTROL, 0x00);
+
+	/* Set DLY = 1 to conform to the I2S standard.
+	 * DLY is only effective when TDM = 0
+	 */
+	max98091_write_reg(dev, M98091_REG_INTERFACE_FORMAT, M98091_DLY_MASK);
+
+	/* Configure system clock */
+	max98091_set_system_clock(dev, dev_cfg->mclk_freq);
+
+	max98091_protocol_config(dev, cfg->dai_type);
+	max98091_audio_fmt_config(dev, &cfg->dai_cfg);
+
+	/* Configure audio paths based on route */
+	switch (cfg->dai_route) {
+	case AUDIO_ROUTE_PLAYBACK:
+		max98091_configure_output(dev);
+		break;
+	default:
+		LOG_DBG("Unsupported audio route selected");
+		break;
+	}
+
+	/* Bring the audio codec out of shutdown mode */
+	max98091_write_reg(dev, M98091_REG_DEVICE_SHUTDOWN, M98091_SHDNN_MASK);
+
+	return 0;
+}
+
+static const struct audio_codec_api max98091_api = {
+	.configure = max98091_configure,
+	.start_output = max98091_start_output,
+	.stop_output = max98091_stop_output,
+	.set_property = max98091_set_property,
+};
+
+static int max98091_init(const struct device *dev)
+{
+	const struct max98091_config *cfg_tan = dev->config;
+	uint8_t device_id;
+
+	if (!i2c_is_ready_dt(&cfg_tan->i2c)) {
+		LOG_ERR("I2C bus not ready");
+		return -ENODEV;
+	}
+
+	max98091_read_reg(dev, M98091_REG_REVISION_ID, &device_id);
+	if (device_id >= M98091_REVA && (device_id <= M98091_REVA + 0x0f)) {
+		LOG_INF("MAX98091 Device ID: 0x%02X", device_id);
+		return 0;
+	}
+
+	LOG_ERR("Invalid MAX98091 Device ID: 0x%02X", device_id);
+	return -EINVAL;
+}
+
+#define MAX98091_INIT(inst)								\
+	static const struct max98091_config max98091_config_##inst = {			\
+		.i2c = I2C_DT_SPEC_INST_GET(inst),					\
+		.mclk_freq = DT_INST_PROP(inst, mclk_frequency)};			\
+	DEVICE_DT_INST_DEFINE(inst, max98091_init, NULL, NULL, &max98091_config_##inst, \
+			      POST_KERNEL, CONFIG_AUDIO_CODEC_INIT_PRIORITY, &max98091_api);
+
+DT_INST_FOREACH_STATUS_OKAY(MAX98091_INIT)