linux-kernel - [PATCH v2 4/4] ASoC: cs4271: Add support for the external mclk

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Message-ID: <20251029093921.624088-5-herve.codina@bootlin.com>
Date: Wed, 29 Oct 2025 10:39:20 +0100
From: Herve Codina <herve.codina@...tlin.com>
To: David Rhodes <david.rhodes@...rus.com>,
	Richard Fitzgerald <rf@...nsource.cirrus.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>,
	Alexander Sverdlin <alexander.sverdlin@...il.com>,
	Nikita Shubin <nikita.shubin@...uefel.me>,
	Axel Lin <axel.lin@...ics.com>,
	Brian Austin <brian.austin@...rus.com>
Cc: linux-sound@...r.kernel.org,
	patches@...nsource.cirrus.com,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Herve Codina <herve.codina@...tlin.com>
Subject: [PATCH v2 4/4] ASoC: cs4271: Add support for the external mclk

The mclk (master clock) of the cs4271 codec can be an input clock.

In this case the connected clock needs to be enabled outside of any
audio stream. Indeed, this clock is needed for i2c communication.

Add support of this clock and enable it before the first i2c transfer.

Signed-off-by: Herve Codina <herve.codina@...tlin.com>
---
 sound/soc/codecs/cs4271.c | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/sound/soc/codecs/cs4271.c b/sound/soc/codecs/cs4271.c
index a9d333e6c723..b8a50b9001e1 100644
--- a/sound/soc/codecs/cs4271.c
+++ b/sound/soc/codecs/cs4271.c
@@ -10,6 +10,7 @@
  * DAPM support not implemented.
  */
 
+#include <linux/clk.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/delay.h>
@@ -163,6 +164,7 @@ struct cs4271_private {
 	/* enable soft reset workaround */
 	bool				enable_soft_reset;
 	struct regulator_bulk_data      supplies[ARRAY_SIZE(supply_names)];
+	struct clk *clk;
 };
 
 static const struct snd_soc_dapm_widget cs4271_dapm_widgets[] = {
@@ -505,6 +507,7 @@ static int cs4271_soc_suspend(struct snd_soc_component *component)
 		return ret;
 
 	regcache_mark_dirty(cs4271->regmap);
+	clk_disable_unprepare(cs4271->clk);
 	regulator_bulk_disable(ARRAY_SIZE(cs4271->supplies), cs4271->supplies);
 
 	return 0;
@@ -522,6 +525,12 @@ static int cs4271_soc_resume(struct snd_soc_component *component)
 		return ret;
 	}
 
+	ret = clk_prepare_enable(cs4271->clk);
+	if (ret) {
+		dev_err(component->dev, "Failed to enable clk: %d\n", ret);
+		return ret;
+	}
+
 	/* Do a proper reset after power up */
 	cs4271_reset(component);
 
@@ -567,22 +576,29 @@ static int cs4271_component_probe(struct snd_soc_component *component)
 		cs4271->enable_soft_reset = cs4271plat->enable_soft_reset;
 	}
 
+	ret = clk_prepare_enable(cs4271->clk);
+	if (ret) {
+		dev_err(component->dev, "Failed to enable clk: %d\n", ret);
+		goto err_disable_regulators;
+	}
+
 	/* Reset codec */
 	cs4271_reset(component);
 
 	ret = regcache_sync(cs4271->regmap);
 	if (ret < 0)
-		goto err_disable_regulators;
+		goto err_disable_clk;
 
 	ret = regmap_update_bits(cs4271->regmap, CS4271_MODE2,
 				 CS4271_MODE2_PDN | CS4271_MODE2_CPEN,
 				 CS4271_MODE2_PDN | CS4271_MODE2_CPEN);
 	if (ret < 0)
-		goto err_disable_regulators;
+		goto err_disable_clk;
 	ret = regmap_update_bits(cs4271->regmap, CS4271_MODE2,
 				 CS4271_MODE2_PDN, 0);
 	if (ret < 0)
-		goto err_disable_regulators;
+		goto err_disable_clk;
+
 	/* Power-up sequence requires 85 uS */
 	udelay(85);
 
@@ -593,6 +609,8 @@ static int cs4271_component_probe(struct snd_soc_component *component)
 
 	return 0;
 
+err_disable_clk:
+	clk_disable_unprepare(cs4271->clk);
 err_disable_regulators:
 	regulator_bulk_disable(ARRAY_SIZE(cs4271->supplies), cs4271->supplies);
 	return ret;
@@ -607,6 +625,7 @@ static void cs4271_component_remove(struct snd_soc_component *component)
 
 	regcache_mark_dirty(cs4271->regmap);
 	regulator_bulk_disable(ARRAY_SIZE(cs4271->supplies), cs4271->supplies);
+	clk_disable_unprepare(cs4271->clk);
 };
 
 static const struct snd_soc_component_driver soc_component_dev_cs4271 = {
@@ -641,6 +660,10 @@ static int cs4271_common_probe(struct device *dev,
 				     "error retrieving RESET GPIO\n");
 	gpiod_set_consumer_name(cs4271->reset, "CS4271 Reset");
 
+	cs4271->clk = devm_clk_get_optional(dev, "mclk");
+	if (IS_ERR(cs4271->clk))
+		return dev_err_probe(dev, PTR_ERR(cs4271->clk), "Failed to get mclk\n");
+
 	for (i = 0; i < ARRAY_SIZE(supply_names); i++)
 		cs4271->supplies[i].supply = supply_names[i];
 
-- 
2.51.0