ASoC: Disable WM8994 VMID for digital only paths

On WM8994 class devices only the analogue portions of the CODEC require
VMID so when running digital only paths we can leave VMID disabled.
On some earlier devices the FLL uses VMID so we don't use DAPM reference
counting alone, we maintain an internal reference count which is also
enabled and disabled by the FLL startup.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>

sound/soc/codecs/wm8994.c

@@ -682,6 +682,97 @@ static int clk_sys_event(struct snd_soc_dapm_widget *w,
 	return 0;
 }
 
+static void vmid_reference(struct snd_soc_codec *codec)
+{
+	struct wm8994_priv *wm8994 = snd_soc_codec_get_drvdata(codec);
+
+	wm8994->vmid_refcount++;
+
+	dev_dbg(codec->dev, "Referencing VMID, refcount is now %d\n",
+		wm8994->vmid_refcount);
+
+	if (wm8994->vmid_refcount == 1) {
+		/* Startup bias, VMID ramp & buffer */
+		snd_soc_update_bits(codec, WM8994_ANTIPOP_2,
+				    WM8994_STARTUP_BIAS_ENA |
+				    WM8994_VMID_BUF_ENA |
+				    WM8994_VMID_RAMP_MASK,
+				    WM8994_STARTUP_BIAS_ENA |
+				    WM8994_VMID_BUF_ENA |
+				    (0x11 << WM8994_VMID_RAMP_SHIFT));
+
+		/* Main bias enable, VMID=2x40k */
+		snd_soc_update_bits(codec, WM8994_POWER_MANAGEMENT_1,
+				    WM8994_BIAS_ENA |
+				    WM8994_VMID_SEL_MASK,
+				    WM8994_BIAS_ENA | 0x2);
+
+		msleep(20);
+	}
+}
+
+static void vmid_dereference(struct snd_soc_codec *codec)
+{
+	struct wm8994_priv *wm8994 = snd_soc_codec_get_drvdata(codec);
+
+	wm8994->vmid_refcount--;
+
+	dev_dbg(codec->dev, "Dereferencing VMID, refcount is now %d\n",
+		wm8994->vmid_refcount);
+
+	if (wm8994->vmid_refcount == 0) {
+		/* Switch over to startup biases */
+		snd_soc_update_bits(codec, WM8994_ANTIPOP_2,
+				    WM8994_BIAS_SRC |
+				    WM8994_STARTUP_BIAS_ENA |
+				    WM8994_VMID_BUF_ENA |
+				    WM8994_VMID_RAMP_MASK,
+				    WM8994_BIAS_SRC |
+				    WM8994_STARTUP_BIAS_ENA |
+				    WM8994_VMID_BUF_ENA |
+				    (1 << WM8994_VMID_RAMP_SHIFT));
+
+		/* Disable main biases */
+		snd_soc_update_bits(codec, WM8994_POWER_MANAGEMENT_1,
+				    WM8994_BIAS_ENA |
+				    WM8994_VMID_SEL_MASK, 0);
+
+		/* Discharge line */
+		snd_soc_update_bits(codec, WM8994_ANTIPOP_1,
+				    WM8994_LINEOUT1_DISCH |
+				    WM8994_LINEOUT2_DISCH,
+				    WM8994_LINEOUT1_DISCH |
+				    WM8994_LINEOUT2_DISCH);
+
+		msleep(5);
+
+		/* Switch off startup biases */
+		snd_soc_update_bits(codec, WM8994_ANTIPOP_2,
+				    WM8994_BIAS_SRC |
+				    WM8994_STARTUP_BIAS_ENA |
+				    WM8994_VMID_BUF_ENA |
+				    WM8994_VMID_RAMP_MASK, 0);
+	}
+}
+
+static int vmid_event(struct snd_soc_dapm_widget *w,
+		      struct snd_kcontrol *kcontrol, int event)
+{
+	struct snd_soc_codec *codec = w->codec;
+
+	switch (event) {
+	case SND_SOC_DAPM_PRE_PMU:
+		vmid_reference(codec);
+		break;
+
+	case SND_SOC_DAPM_POST_PMD:
+		vmid_dereference(codec);
+		break;
+	}
+
+	return 0;
+}
+
 static void wm8994_update_class_w(struct snd_soc_codec *codec)
 {
 	struct wm8994_priv *wm8994 = snd_soc_codec_get_drvdata(codec);
@@ -1209,7 +1300,8 @@ SND_SOC_DAPM_INPUT("Clock"),
 
 SND_SOC_DAPM_SUPPLY_S("MICBIAS Supply", 1, SND_SOC_NOPM, 0, 0, micbias_ev,
 		      SND_SOC_DAPM_PRE_PMU),
-SND_SOC_DAPM_SUPPLY("VMID", SND_SOC_NOPM, 0, 0, NULL, 0),
+SND_SOC_DAPM_SUPPLY("VMID", SND_SOC_NOPM, 0, 0, vmid_event,
+		    SND_SOC_DAPM_PRE_PMU | SND_SOC_DAPM_POST_PMD),
 
 SND_SOC_DAPM_SUPPLY("CLK_SYS", SND_SOC_NOPM, 0, 0, clk_sys_event,
 		    SND_SOC_DAPM_POST_PMU | SND_SOC_DAPM_PRE_PMD),
@@ -1633,10 +1725,12 @@ static int _wm8994_set_fll(struct snd_soc_codec *codec, int id, int src,
 			  unsigned int freq_in, unsigned int freq_out)
 {
 	struct wm8994_priv *wm8994 = snd_soc_codec_get_drvdata(codec);
+	struct wm8994 *control = codec->control_data;
 	int reg_offset, ret;
 	struct fll_div fll;
 	u16 reg, aif1, aif2;
 	unsigned long timeout;
+	bool was_enabled;
 
 	aif1 = snd_soc_read(codec, WM8994_AIF1_CLOCKING_1)
 		& WM8994_AIF1CLK_ENA;
@@ -1657,6 +1751,9 @@ static int _wm8994_set_fll(struct snd_soc_codec *codec, int id, int src,
 		return -EINVAL;
 	}
 
+	reg = snd_soc_read(codec, WM8994_FLL1_CONTROL_1 + reg_offset);
+	was_enabled = reg & WM8994_FLL1_ENA;
+
 	switch (src) {
 	case 0:
 		/* Allow no source specification when stopping */
@@ -1723,6 +1820,21 @@ static int _wm8994_set_fll(struct snd_soc_codec *codec, int id, int src,
 
 	/* Enable (with fractional mode if required) */
 	if (freq_out) {
+		/* Enable VMID if we need it */
+		if (!was_enabled) {
+			switch (control->type) {
+			case WM8994:
+				vmid_reference(codec);
+				break;
+			case WM8958:
+				if (wm8994->revision < 1)
+					vmid_reference(codec);
+				break;
+			default:
+				break;
+			}
+		}
+
 		if (fll.k)
 			reg = WM8994_FLL1_ENA | WM8994_FLL1_FRAC;
 		else
@@ -1740,6 +1852,20 @@ static int _wm8994_set_fll(struct snd_soc_codec *codec, int id, int src,
 		} else {
 			msleep(5);
 		}
+	} else {
+		if (was_enabled) {
+			switch (control->type) {
+			case WM8994:
+				vmid_dereference(codec);
+				break;
+			case WM8958:
+				if (wm8994->revision < 1)
+					vmid_dereference(codec);
+				break;
+			default:
+				break;
+			}
+		}
 	}
 
 	wm8994->fll[id].in = freq_in;
@@ -1856,9 +1982,6 @@ static int wm8994_set_bias_level(struct snd_soc_codec *codec,
 		break;
 
 	case SND_SOC_BIAS_PREPARE:
-		/* VMID=2x40k */
-		snd_soc_update_bits(codec, WM8994_POWER_MANAGEMENT_1,
-				    WM8994_VMID_SEL_MASK, 0x2);
 		break;
 
 	case SND_SOC_BIAS_STANDBY:
@@ -1900,65 +2023,13 @@ static int wm8994_set_bias_level(struct snd_soc_codec *codec,
 					    WM8994_LINEOUT2_DISCH,
 					    WM8994_LINEOUT1_DISCH |
 					    WM8994_LINEOUT2_DISCH);
-
-			/* Startup bias, VMID ramp & buffer */
-			snd_soc_update_bits(codec, WM8994_ANTIPOP_2,
-					    WM8994_STARTUP_BIAS_ENA |
-					    WM8994_VMID_BUF_ENA |
-					    WM8994_VMID_RAMP_MASK,
-					    WM8994_STARTUP_BIAS_ENA |
-					    WM8994_VMID_BUF_ENA |
-					    (0x11 << WM8994_VMID_RAMP_SHIFT));
-
-			/* Main bias enable, VMID=2x40k */
-			snd_soc_update_bits(codec, WM8994_POWER_MANAGEMENT_1,
-					    WM8994_BIAS_ENA |
-					    WM8994_VMID_SEL_MASK,
-					    WM8994_BIAS_ENA | 0x2);
-
-			msleep(20);
 		}
 
-		/* VMID=2x500k */
-		snd_soc_update_bits(codec, WM8994_POWER_MANAGEMENT_1,
-				    WM8994_VMID_SEL_MASK, 0x4);
 
 		break;
 
 	case SND_SOC_BIAS_OFF:
 		if (codec->dapm.bias_level == SND_SOC_BIAS_STANDBY) {
-			/* Switch over to startup biases */
-			snd_soc_update_bits(codec, WM8994_ANTIPOP_2,
-					    WM8994_BIAS_SRC |
-					    WM8994_STARTUP_BIAS_ENA |
-					    WM8994_VMID_BUF_ENA |
-					    WM8994_VMID_RAMP_MASK,
-					    WM8994_BIAS_SRC |
-					    WM8994_STARTUP_BIAS_ENA |
-					    WM8994_VMID_BUF_ENA |
-					    (1 << WM8994_VMID_RAMP_SHIFT));
-
-			/* Disable main biases */
-			snd_soc_update_bits(codec, WM8994_POWER_MANAGEMENT_1,
-					    WM8994_BIAS_ENA |
-					    WM8994_VMID_SEL_MASK, 0);
-
-			/* Discharge line */
-			snd_soc_update_bits(codec, WM8994_ANTIPOP_1,
-					    WM8994_LINEOUT1_DISCH |
-					    WM8994_LINEOUT2_DISCH,
-					    WM8994_LINEOUT1_DISCH |
-					    WM8994_LINEOUT2_DISCH);
-
-			msleep(5);
-
-			/* Switch off startup biases */
-			snd_soc_update_bits(codec, WM8994_ANTIPOP_2,
-					    WM8994_BIAS_SRC |
-					    WM8994_STARTUP_BIAS_ENA |
-					    WM8994_VMID_BUF_ENA |
-					    WM8994_VMID_RAMP_MASK, 0);
-
 			wm8994->cur_fw = NULL;
 
 			pm_runtime_put(codec->dev);

sound/soc/codecs/wm8994.h

@@ -83,6 +83,8 @@ struct wm8994_priv {
 	struct completion fll_locked[2];
 	bool fll_locked_irq;
 
+	int vmid_refcount;
+
 	int dac_rates[2];
 	int lrclk_shared[2];