ASoC: nau8821: Add slew rate controls.

The patch supports DMIC clock slew rate controls.
Signed-off-by: Seven Lee <wtli@nuvoton.com>
Link: https://lore.kernel.org/r/20231107035230.1241683-3-wtli@nuvoton.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/nau8821.c

@@ -1738,6 +1738,10 @@ static int nau8821_read_device_properties(struct device *dev,
 		&nau8821->dmic_clk_threshold);
 	if (ret)
 		nau8821->dmic_clk_threshold = 3072000;
+	ret = device_property_read_u32(dev, "nuvoton,dmic-slew-rate",
+		&nau8821->dmic_slew_rate);
+	if (ret)
+		nau8821->dmic_slew_rate = 0;
 
 	return 0;
 }
@@ -1797,6 +1801,9 @@ static void nau8821_init_regs(struct nau8821 *nau8821)
 		NAU8821_ADC_SYNC_DOWN_MASK, NAU8821_ADC_SYNC_DOWN_64);
 	regmap_update_bits(regmap, NAU8821_R2C_DAC_CTRL1,
 		NAU8821_DAC_OVERSAMPLE_MASK, NAU8821_DAC_OVERSAMPLE_64);
+	regmap_update_bits(regmap, NAU8821_R13_DMIC_CTRL,
+		NAU8821_DMIC_SLEW_MASK, nau8821->dmic_slew_rate <<
+		NAU8821_DMIC_SLEW_SFT);
 	if (nau8821->left_input_single_end) {
 		regmap_update_bits(regmap, NAU8821_R6B_PGA_MUTE,
 			NAU8821_MUTE_MICNL_EN, NAU8821_MUTE_MICNL_EN);

sound/soc/codecs/nau8821.h

@@ -236,6 +236,8 @@
 #define NAU8821_DMIC_SRC_MASK	(0x3 << NAU8821_DMIC_SRC_SFT)
 #define NAU8821_CLK_DMIC_SRC	(0x2 << NAU8821_DMIC_SRC_SFT)
 #define NAU8821_DMIC_EN_SFT	0
+#define NAU8821_DMIC_SLEW_SFT  8
+#define NAU8821_DMIC_SLEW_MASK (0x7 << NAU8821_DMIC_SLEW_SFT)
 
 /* GPIO12_CTRL (0x1a) */
 #define NAU8821_JKDET_PULL_UP	(0x1 << 11) /* 0 - pull down, 1 - pull up */
@@ -573,6 +575,7 @@ struct nau8821 {
 	int jack_eject_debounce;
 	int fs;
 	int dmic_clk_threshold;
+	int dmic_slew_rate;
 	int key_enable;
 };