ASoC: wm8994: Add support for MCLKn clock gating

As an intermediate step before covering the clocking subsystem
of the CODEC entirely by the clk API add handling of external CODEC's
master clocks in DAPM events when the AIFn clocks are sourced directly
from MCLKn; when FLLn are used we enable/disable respective MCLKn
before/after FLLn is enabled/disabled.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20190920130218.32690-5-s.nawrocki@samsung.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/wm8994.c

@@ -1033,6 +1033,45 @@ static bool wm8994_check_class_w_digital(struct snd_soc_component *component)
 	return true;
 }
 
+static int aif_mclk_set(struct snd_soc_component *component, int aif, bool enable)
+{
+	struct wm8994_priv *wm8994 = snd_soc_component_get_drvdata(component);
+	unsigned int offset, val, clk_idx;
+	int ret;
+
+	if (aif)
+		offset = 4;
+	else
+		offset = 0;
+
+	val = snd_soc_component_read32(component, WM8994_AIF1_CLOCKING_1 + offset);
+	val &= WM8994_AIF1CLK_SRC_MASK;
+
+	switch (val) {
+	case 0:
+		clk_idx = WM8994_MCLK1;
+		break;
+	case 1:
+		clk_idx = WM8994_MCLK2;
+		break;
+	default:
+		return 0;
+	}
+
+	if (enable) {
+		ret = clk_prepare_enable(wm8994->mclk[clk_idx].clk);
+		if (ret < 0) {
+			dev_err(component->dev,	"Failed to enable MCLK%d\n",
+				clk_idx);
+			return ret;
+		}
+	} else {
+		clk_disable_unprepare(wm8994->mclk[clk_idx].clk);
+	}
+
+	return 0;
+}
+
 static int aif1clk_ev(struct snd_soc_dapm_widget *w,
 		      struct snd_kcontrol *kcontrol, int event)
 {
@@ -1040,7 +1079,7 @@ static int aif1clk_ev(struct snd_soc_dapm_widget *w,
 	struct wm8994_priv *wm8994 = snd_soc_component_get_drvdata(component);
 	struct wm8994 *control = wm8994->wm8994;
 	int mask = WM8994_AIF1DAC1L_ENA | WM8994_AIF1DAC1R_ENA;
-	int i;
+	int ret, i;
 	int dac;
 	int adc;
 	int val;
@@ -1056,6 +1095,10 @@ static int aif1clk_ev(struct snd_soc_dapm_widget *w,
 
 	switch (event) {
 	case SND_SOC_DAPM_PRE_PMU:
+		ret = aif_mclk_set(component, 0, true);
+		if (ret < 0)
+			return ret;
+
 		/* Don't enable timeslot 2 if not in use */
 		if (wm8994->channels[0] <= 2)
 			mask &= ~(WM8994_AIF1DAC2L_ENA | WM8994_AIF1DAC2R_ENA);
@@ -1128,6 +1171,12 @@ static int aif1clk_ev(struct snd_soc_dapm_widget *w,
 		break;
 	}
 
+	switch (event) {
+	case SND_SOC_DAPM_POST_PMD:
+		aif_mclk_set(component, 0, false);
+		break;
+	}
+
 	return 0;
 }
 
@@ -1135,13 +1184,17 @@ static int aif2clk_ev(struct snd_soc_dapm_widget *w,
 		      struct snd_kcontrol *kcontrol, int event)
 {
 	struct snd_soc_component *component = snd_soc_dapm_to_component(w->dapm);
-	int i;
+	int ret, i;
 	int dac;
 	int adc;
 	int val;
 
 	switch (event) {
 	case SND_SOC_DAPM_PRE_PMU:
+		ret = aif_mclk_set(component, 1, true);
+		if (ret < 0)
+			return ret;
+
 		val = snd_soc_component_read32(component, WM8994_AIF2_CONTROL_1);
 		if ((val & WM8994_AIF2ADCL_SRC) &&
 		    (val & WM8994_AIF2ADCR_SRC))
@@ -1213,6 +1266,12 @@ static int aif2clk_ev(struct snd_soc_dapm_widget *w,
 		break;
 	}
 
+	switch (event) {
+	case SND_SOC_DAPM_POST_PMD:
+		aif_mclk_set(component, 1, false);
+		break;
+	}
+
 	return 0;
 }
 
@@ -1618,10 +1677,10 @@ SND_SOC_DAPM_POST("Late Disable PGA", late_disable_ev)
 static const struct snd_soc_dapm_widget wm8994_lateclk_widgets[] = {
 SND_SOC_DAPM_SUPPLY("AIF1CLK", WM8994_AIF1_CLOCKING_1, 0, 0, aif1clk_ev,
 		    SND_SOC_DAPM_PRE_PMU | SND_SOC_DAPM_POST_PMU |
-		    SND_SOC_DAPM_PRE_PMD),
+		    SND_SOC_DAPM_PRE_PMD | SND_SOC_DAPM_POST_PMD),
 SND_SOC_DAPM_SUPPLY("AIF2CLK", WM8994_AIF2_CLOCKING_1, 0, 0, aif2clk_ev,
 		    SND_SOC_DAPM_PRE_PMU | SND_SOC_DAPM_POST_PMU |
-		    SND_SOC_DAPM_PRE_PMD),
+		    SND_SOC_DAPM_PRE_PMD | SND_SOC_DAPM_POST_PMD),
 SND_SOC_DAPM_PGA("Direct Voice", SND_SOC_NOPM, 0, 0, NULL, 0),
 SND_SOC_DAPM_MIXER("SPKL", WM8994_POWER_MANAGEMENT_3, 8, 0,
 		   left_speaker_mixer, ARRAY_SIZE(left_speaker_mixer)),
@@ -2136,6 +2195,7 @@ static int _wm8994_set_fll(struct snd_soc_component *component, int id, int src,
 	u16 reg, clk1, aif_reg, aif_src;
 	unsigned long timeout;
 	bool was_enabled;
+	struct clk *mclk;
 
 	switch (id) {
 	case WM8994_FLL1:
@@ -2211,6 +2271,27 @@ static int _wm8994_set_fll(struct snd_soc_component *component, int id, int src,
 	snd_soc_component_update_bits(component, WM8994_FLL1_CONTROL_1 + reg_offset,
 			    WM8994_FLL1_ENA, 0);
 
+	/* Disable MCLK if needed before we possibly change to new clock parent */
+	if (was_enabled) {
+		reg = snd_soc_component_read32(component, WM8994_FLL1_CONTROL_5
+							+ reg_offset);
+		reg = ((reg & WM8994_FLL1_REFCLK_SRC_MASK)
+			>> WM8994_FLL1_REFCLK_SRC_SHIFT) + 1;
+
+		switch (reg) {
+		case WM8994_FLL_SRC_MCLK1:
+			mclk = wm8994->mclk[WM8994_MCLK1].clk;
+			break;
+		case WM8994_FLL_SRC_MCLK2:
+			mclk = wm8994->mclk[WM8994_MCLK2].clk;
+			break;
+		default:
+			mclk = NULL;
+		}
+
+		clk_disable_unprepare(mclk);
+	}
+
 	if (wm8994->fll_byp && src == WM8994_FLL_SRC_BCLK &&
 	    freq_in == freq_out && freq_out) {
 		dev_dbg(component->dev, "Bypassing FLL%d\n", id + 1);
@@ -2255,10 +2336,29 @@ static int _wm8994_set_fll(struct snd_soc_component *component, int id, int src,
 	/* Clear any pending completion from a previous failure */
 	try_wait_for_completion(&wm8994->fll_locked[id]);
 
+	switch (src) {
+	case WM8994_FLL_SRC_MCLK1:
+		mclk = wm8994->mclk[WM8994_MCLK1].clk;
+		break;
+	case WM8994_FLL_SRC_MCLK2:
+		mclk = wm8994->mclk[WM8994_MCLK2].clk;
+		break;
+	default:
+		mclk = NULL;
+	}
+
 	/* Enable (with fractional mode if required) */
 	if (freq_out) {
+		ret = clk_prepare_enable(mclk);
+		if (ret < 0) {
+			dev_err(component->dev, "Failed to enable MCLK for FLL%d\n",
+				id + 1);
+			return ret;
+		}
+
 		/* Enable VMID if we need it */
 		if (!was_enabled) {
+
 			active_reference(component);
 
 			switch (control->type) {