+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;
+}
+