ASoC: intel/sdw_utils: Add volume limits to CS35L56

Merge series from Stefan Binding <sbinding@opensource.cirrus.com>:

Both CS35L56 and CS42L43 have maximum volumes above 0dB.
However, for many use cases, this can cause distorted audio, depending
various factors, such as other signal-processing elements in the chain,
for example if the audio passes through a gain control before reaching
the amp or the signal path has been tuned for a particular maximum
gain in the amp.

In the cases where systems use the soc_sdw_* drivers, audio above the
0dB volume will likely always be distorted, therefore apply a 0dB
limit to those devices.

Stefan Binding (2):
  ASoC: intel/sdw_utils: Add volume limit to cs42l43 speakers
  ASoC: intel/sdw_utils: Add volume limit to cs35l56 speakers

 include/sound/soc_sdw_utils.h                |  1 +
 sound/soc/sdw_utils/soc_sdw_bridge_cs35l56.c |  4 ++++
 sound/soc/sdw_utils/soc_sdw_cs42l43.c        | 10 ++++++++
 sound/soc/sdw_utils/soc_sdw_cs_amp.c         | 24 ++++++++++++++++++++
 4 files changed, 39 insertions(+)

--
2.43.0

include/sound/soc_sdw_utils.h

@@ -226,6 +226,7 @@ int asoc_sdw_cs_amp_init(struct snd_soc_card *card,
 			 bool playback);
 int asoc_sdw_cs_spk_feedback_rtd_init(struct snd_soc_pcm_runtime *rtd,
 				      struct snd_soc_dai *dai);
+int asoc_sdw_cs35l56_volume_limit(struct snd_soc_card *card, const char *name_prefix);
 
 /* MAXIM codec support */
 int asoc_sdw_maxim_init(struct snd_soc_card *card,

sound/soc/sdw_utils/soc_sdw_bridge_cs35l56.c

@@ -60,6 +60,10 @@ static int asoc_sdw_bridge_cs35l56_asp_init(struct snd_soc_pcm_runtime *rtd)
 
 	/* 4 x 16-bit sample slots and FSYNC=48000, BCLK=3.072 MHz */
 	for_each_rtd_codec_dais(rtd, i, codec_dai) {
+		ret = asoc_sdw_cs35l56_volume_limit(card, codec_dai->component->name_prefix);
+		if (ret)
+			return ret;
+
 		ret = snd_soc_dai_set_tdm_slot(codec_dai, tx_mask, rx_mask, 4, 16);
 		if (ret < 0)
 			return ret;

sound/soc/sdw_utils/soc_sdw_cs42l43.c

@@ -20,6 +20,8 @@
 #include <sound/soc-dapm.h>
 #include <sound/soc_sdw_utils.h>
 
+#define CS42L43_SPK_VOLUME_0DB	128 /* 0dB Max */
+
 static const struct snd_soc_dapm_route cs42l43_hs_map[] = {
 	{ "Headphone", NULL, "cs42l43 AMP3_OUT" },
 	{ "Headphone", NULL, "cs42l43 AMP4_OUT" },
@@ -117,6 +119,14 @@ int asoc_sdw_cs42l43_spk_rtd_init(struct snd_soc_pcm_runtime *rtd, struct snd_so
 			return -ENOMEM;
 	}
 
+	ret = snd_soc_limit_volume(card, "cs42l43 Speaker Digital Volume",
+				   CS42L43_SPK_VOLUME_0DB);
+	if (ret)
+		dev_err(card->dev, "cs42l43 speaker volume limit failed: %d\n", ret);
+	else
+		dev_info(card->dev, "Setting CS42L43 Speaker volume limit to %d\n",
+			 CS42L43_SPK_VOLUME_0DB);
+
 	ret = snd_soc_dapm_add_routes(&card->dapm, cs42l43_spk_map,
 				      ARRAY_SIZE(cs42l43_spk_map));
 	if (ret)

sound/soc/sdw_utils/soc_sdw_cs_amp.c

@@ -16,6 +16,25 @@
 
 #define CODEC_NAME_SIZE	8
 #define CS_AMP_CHANNELS_PER_AMP	4
+#define CS35L56_SPK_VOLUME_0DB 400 /* 0dB Max */
+
+int asoc_sdw_cs35l56_volume_limit(struct snd_soc_card *card, const char *name_prefix)
+{
+	char *volume_ctl_name;
+	int ret;
+
+	volume_ctl_name = kasprintf(GFP_KERNEL, "%s Speaker Volume", name_prefix);
+	if (!volume_ctl_name)
+		return -ENOMEM;
+
+	ret = snd_soc_limit_volume(card, volume_ctl_name, CS35L56_SPK_VOLUME_0DB);
+	if (ret)
+		dev_err(card->dev, "%s limit set failed: %d\n", volume_ctl_name, ret);
+
+	kfree(volume_ctl_name);
+	return ret;
+}
+EXPORT_SYMBOL_NS(asoc_sdw_cs35l56_volume_limit, "SND_SOC_SDW_UTILS");
 
 int asoc_sdw_cs_spk_rtd_init(struct snd_soc_pcm_runtime *rtd, struct snd_soc_dai *dai)
 {
@@ -40,6 +59,11 @@ int asoc_sdw_cs_spk_rtd_init(struct snd_soc_pcm_runtime *rtd, struct snd_soc_dai
 
 		snprintf(widget_name, sizeof(widget_name), "%s SPK",
 			 codec_dai->component->name_prefix);
+
+		ret = asoc_sdw_cs35l56_volume_limit(card, codec_dai->component->name_prefix);
+		if (ret)
+			return ret;
+
 		ret = snd_soc_dapm_add_routes(&card->dapm, &route, 1);
 		if (ret)
 			return ret;