[PATCH v2 6/7] ASoC: tas2764: expose SDOUT bus keeper via set_tdm_idle operation

James Calligeros
2025-12-21T09:37:13Z

TAS2764, and the Apple-exclusive variant SN012776, include bus keepers
on the SDOUT pin that can be configured to alter the behaviour of the
SDOUT pin during specified TDM slots. The chip can either leave the
bus floating (default/uninitialised behaviour) or fill the specified
slots with zeroes.

Expose the SDOUT bus keeper and allow it to be configured using the
set_tdm_idle DAI op. The mask must be cropped to only cover slots
valid for the configured BCLK ratio, so introduce a set_bclk_ratio
op that properly configures this.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
---
sound/soc/codecs/tas2764.c | 95 +++++++++++++++++++++++++
sound/soc/codecs/tas2764.h | 11 +++
2 files changed, 106 insertions(+)

diff --git a/sound/soc/codecs/tas2764.c b/sound/soc/codecs/tas2764.c
index 36e25e48b354..423b7073b302 100644
--- a/sound/soc/codecs/tas2764.c
+++ b/sound/soc/codecs/tas2764.c
@@ -44,6 +44,11 @@ struct tas2764_priv {

bool dac_powered;
bool unmuted;
+
+ struct {
+ int tx_mode;
+ unsigned int tx_mask;
+ } idle_slot_config;
};

#include "tas2764-quirks.h"
@@ -509,11 +514,101 @@ static int tas2764_set_dai_tdm_slot(struct snd_soc_dai *dai,
return 0;
}

+static int tas2764_write_sdout_idle_mask(struct tas2764_priv *tas2764, u32 mask)
+{
+ struct snd_soc_component *component = tas2764->component;
+ int i, ret;
+
+ /* Hardware supports up to 64 slots, but we don't */
+ for (i = 0; i < 4; i++) {
+ ret = snd_soc_component_write(component,
+ TAS2764_SDOUT_HIZ_1 + i,
+ (mask >> (i * 8)) & 0xff);
+ if (ret < 0)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int tas2764_set_dai_tdm_idle(struct snd_soc_dai *dai,
+ unsigned int tx_mask, unsigned int rx_mask,
+ int tx_mode, int rx_mode)
+{
+ struct snd_soc_component *component = dai->component;
+ struct tas2764_priv *tas2764 = snd_soc_component_get_drvdata(component);
+ int ret;
+
+ /* We don't support setting anything on SDIN */
+ if (rx_mode)
+ return -EOPNOTSUPP;
+
+ if (tas2764->idle_slot_config.tx_mask == tx_mask &&
+ tas2764->idle_slot_config.tx_mode == tx_mode)
+ return 0;
+
+ switch (tx_mode) {
+ case SND_SOC_DAI_TDM_IDLE_ZERO:
+ if (!tx_mask)
+ return -EINVAL;
+
+ ret = tas2764_write_sdout_idle_mask(tas2764, tx_mask);
+ if (ret < 0)
+ return ret;
+
+ ret = snd_soc_component_update_bits(component,
+ TAS2764_SDOUT_HIZ_9,
+ TAS2764_SDOUT_HIZ_9_FORCE_0_EN,
+ TAS2764_SDOUT_HIZ_9_FORCE_0_EN);
+ if (ret < 0)
+ return ret;
+
+ tas2764->idle_slot_config.tx_mask = tx_mask;
+ tas2764->idle_slot_config.tx_mode = tx_mode;
+ break;
+ case SND_SOC_DAI_TDM_IDLE_HIZ:
+ case SND_SOC_DAI_TDM_IDLE_OFF:
+ /* HiZ mode does not support a slot mask */
+ ret = tas2764_write_sdout_idle_mask(tas2764, 0);
+ if (ret < 0)
+ return ret;
+
+ ret = snd_soc_component_update_bits(component,
+ TAS2764_SDOUT_HIZ_9,
+ TAS2764_SDOUT_HIZ_9_FORCE_0_EN, 0);
+ if (ret < 0)
+ return ret;
+
+ tas2764->idle_slot_config.tx_mask = 0;
+ tas2764->idle_slot_config.tx_mode = tx_mode;
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
+/* The SDOUT idle slot mask must be cropped based on the BCLK ratio */
+static int tas2764_set_bclk_ratio(struct snd_soc_dai *dai, unsigned int ratio)
+{
+ struct tas2764_priv *tas2764 = snd_soc_component_get_drvdata(dai->component);
+
+ if (!tas2764->idle_slot_config.tx_mask)
+ return 0;
+
+ tas2764->idle_slot_config.tx_mask &= GENMASK((ratio / 8) - 1, 0);
+
+ return tas2764_write_sdout_idle_mask(tas2764, tas2764->idle_slot_config.tx_mask);
+}
+
static const struct snd_soc_dai_ops tas2764_dai_ops = {
.mute_stream = tas2764_mute,
.hw_params = tas2764_hw_params,
.set_fmt = tas2764_set_fmt,
+ .set_bclk_ratio = tas2764_set_bclk_ratio,
.set_tdm_slot = tas2764_set_dai_tdm_slot,
+ .set_tdm_idle = tas2764_set_dai_tdm_idle,
.no_capture_mute = 1,
};

diff --git a/sound/soc/codecs/tas2764.h b/sound/soc/codecs/tas2764.h
index 538290ed3d92..4494bc4889dc 100644
--- a/sound/soc/codecs/tas2764.h
+++ b/sound/soc/codecs/tas2764.h
@@ -126,4 +126,15 @@

#define TAS2764_BOP_CFG0 TAS2764_REG(0X0, 0x1d)

+#define TAS2764_SDOUT_HIZ_1 TAS2764_REG(0x1, 0x3d)
+#define TAS2764_SDOUT_HIZ_2 TAS2764_REG(0x1, 0x3e)
+#define TAS2764_SDOUT_HIZ_3 TAS2764_REG(0x1, 0x3f)
+#define TAS2764_SDOUT_HIZ_4 TAS2764_REG(0x1, 0x40)
+#define TAS2764_SDOUT_HIZ_5 TAS2764_REG(0x1, 0x41)
+#define TAS2764_SDOUT_HIZ_6 TAS2764_REG(0x1, 0x42)
+#define TAS2764_SDOUT_HIZ_7 TAS2764_REG(0x1, 0x43)
+#define TAS2764_SDOUT_HIZ_8 TAS2764_REG(0x1, 0x44)
+#define TAS2764_SDOUT_HIZ_9 TAS2764_REG(0x1, 0x45)
+#define TAS2764_SDOUT_HIZ_9_FORCE_0_EN BIT(7)
+
#endif /* __TAS2764__ */

--
2.52.0