ASoC: nau8822: add MCLK support

This change adds MCLK clock handling directly within driver.
When used in combination with simple-audio-card, and mclk-fs is set,
simple-audio-card will change MCLK frequency before configuring PLL.
In some cases, however, MCLK reference clock should be static (see [1]),
which means it needs to be moved away from simple-audio-card.

[1]: https://lore.kernel.org/all/ZfBdxrzX3EnPuGOn@ediswmail9.ad.cirrus.com/Signed-off-by: Andrejs Cainikovs <andrejs.cainikovs@toradex.com>
Link: https://msgid.link/r/20240613084652.13113-4-andrejs.cainikovs@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/nau8822.c

@@ -14,6 +14,7 @@
 #include <linux/moduleparam.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/pm.h>
 #include <linux/i2c.h>
@@ -773,11 +774,26 @@ static int nau8822_set_dai_sysclk(struct snd_soc_dai *dai, int clk_id,
 {
 	struct snd_soc_component *component = dai->component;
 	struct nau8822 *nau8822 = snd_soc_component_get_drvdata(component);
+	unsigned long mclk_freq;
 
 	nau8822->div_id = clk_id;
 	nau8822->sysclk = freq;
+
+	if (nau8822->mclk) {
+		mclk_freq = clk_get_rate(nau8822->mclk);
+		if (mclk_freq != freq) {
+			int ret = nau8822_set_pll(dai, NAU8822_CLK_MCLK,
+				NAU8822_CLK_MCLK, mclk_freq, freq);
+			if (ret) {
+				dev_err(component->dev, "Failed to set PLL\n");
+				return ret;
+			}
+			nau8822->div_id = NAU8822_CLK_PLL;
+		}
+	}
+
 	dev_dbg(component->dev, "master sysclk %dHz, source %s\n", freq,
-		clk_id == NAU8822_CLK_PLL ? "PLL" : "MCLK");
+		nau8822->div_id == NAU8822_CLK_PLL ? "PLL" : "MCLK");
 
 	return 0;
 }
@@ -848,7 +864,7 @@ static int nau8822_hw_params(struct snd_pcm_substream *substream,
 {
 	struct snd_soc_component *component = dai->component;
 	struct nau8822 *nau8822 = snd_soc_component_get_drvdata(component);
-	int val_len = 0, val_rate = 0;
+	int div = 0, val_len = 0, val_rate = 0;
 	unsigned int ctrl_val, bclk_fs, bclk_div;
 
 	/* make BCLK and LRC divide configuration if the codec as master. */
@@ -915,8 +931,10 @@ static int nau8822_hw_params(struct snd_pcm_substream *substream,
 	/* If the master clock is from MCLK, provide the runtime FS for driver
 	 * to get the master clock prescaler configuration.
 	 */
-	if (nau8822->div_id == NAU8822_CLK_MCLK)
-		nau8822_config_clkdiv(dai, 0, params_rate(params));
+	if (nau8822->div_id != NAU8822_CLK_MCLK)
+		div = nau8822->pll.mclk_scaler;
+
+	nau8822_config_clkdiv(dai, div, params_rate(params));
 
 	return 0;
 }
@@ -940,17 +958,34 @@ static int nau8822_mute(struct snd_soc_dai *dai, int mute, int direction)
 static int nau8822_set_bias_level(struct snd_soc_component *component,
 				 enum snd_soc_bias_level level)
 {
+	struct nau8822 *nau8822 = snd_soc_component_get_drvdata(component);
+
 	switch (level) {
 	case SND_SOC_BIAS_ON:
 		break;
 
 	case SND_SOC_BIAS_PREPARE:
+		if (nau8822->mclk &&
+			snd_soc_component_get_bias_level(component) != SND_SOC_BIAS_ON) {
+			int ret = clk_prepare_enable(nau8822->mclk);
+
+			if (ret) {
+				dev_err(component->dev,
+					"Failed to enable MCLK: %d\n", ret);
+				return ret;
+			}
+		}
+
 		snd_soc_component_update_bits(component,
 			NAU8822_REG_POWER_MANAGEMENT_1,
 			NAU8822_REFIMP_MASK, NAU8822_REFIMP_80K);
 		break;
 
 	case SND_SOC_BIAS_STANDBY:
+		if (nau8822->mclk &&
+			snd_soc_component_get_bias_level(component) != SND_SOC_BIAS_OFF)
+			clk_disable_unprepare(nau8822->mclk);
+
 		snd_soc_component_update_bits(component,
 			NAU8822_REG_POWER_MANAGEMENT_1,
 			NAU8822_IOBUF_EN | NAU8822_ABIAS_EN,
@@ -1127,6 +1162,11 @@ static int nau8822_i2c_probe(struct i2c_client *i2c)
 	}
 	i2c_set_clientdata(i2c, nau8822);
 
+	nau8822->mclk = devm_clk_get_optional(&i2c->dev, "mclk");
+	if (IS_ERR(nau8822->mclk))
+		return dev_err_probe(&i2c->dev, PTR_ERR(nau8822->mclk),
+			"Error getting mclk\n");
+
 	nau8822->regmap = devm_regmap_init_i2c(i2c, &nau8822_regmap_config);
 	if (IS_ERR(nau8822->regmap)) {
 		ret = PTR_ERR(nau8822->regmap);

sound/soc/codecs/nau8822.h

@@ -215,6 +215,7 @@ struct nau8822_pll {
 struct nau8822 {
 	struct device *dev;
 	struct regmap *regmap;
+	struct clk *mclk;
 	struct nau8822_pll pll;
 	int sysclk;
 	int div_id;