ASoC: qcom: Parse "pin-switches" and "widgets" from DT

Merge series from Stephan Gerhold <stephan@gerhold.net>:

Some sound card setups might require extra pin switches to allow
turning off certain audio components. simple-card supports this
already using the "pin-switches" and "widgets" device tree property.
This series makes it possible to use the same properties for the Qcom
sound cards.

To implement that, the function that parses the "pin-switches" property
in simple-card-utils.c is first moved into the ASoC core. Then two
simple function calls are added to the common Qcom sound card DT parser.
Finally there is a small patch for the msm8916-wcd-analog codec to make
it possible to model sound card setups used in some MSM8916 smartphones.
(See PATCH 2/4 for an explanation of some real example use cases.)

Using pin switches rather than patching codec drivers with switches was
originally suggested by Mark Brown on a patch for the tfa989x codec:
https://lore.kernel.org/alsa-devel/YXaMVHo9drCIuD3u@sirena.org.uk/

1 files changed, 50 insertions, 0 deletions

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 1d62160f96b1..434e61b46983 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -2823,6 +2823,56 @@ int snd_soc_of_parse_audio_simple_widgets(struct snd_soc_card *card,
 }
 EXPORT_SYMBOL_GPL(snd_soc_of_parse_audio_simple_widgets);
 
+int snd_soc_of_parse_pin_switches(struct snd_soc_card *card, const char *prop)
+{
+	const unsigned int nb_controls_max = 16;
+	const char **strings, *control_name;
+	struct snd_kcontrol_new *controls;
+	struct device *dev = card->dev;
+	unsigned int i, nb_controls;
+	int ret;
+
+	if (!of_property_read_bool(dev->of_node, prop))
+		return 0;
+
+	strings = devm_kcalloc(dev, nb_controls_max,
+			       sizeof(*strings), GFP_KERNEL);
+	if (!strings)
+		return -ENOMEM;
+
+	ret = of_property_read_string_array(dev->of_node, prop,
+					    strings, nb_controls_max);
+	if (ret < 0)
+		return ret;
+
+	nb_controls = (unsigned int)ret;
+
+	controls = devm_kcalloc(dev, nb_controls,
+				sizeof(*controls), GFP_KERNEL);
+	if (!controls)
+		return -ENOMEM;
+
+	for (i = 0; i < nb_controls; i++) {
+		control_name = devm_kasprintf(dev, GFP_KERNEL,
+					      "%s Switch", strings[i]);
+		if (!control_name)
+			return -ENOMEM;
+
+		controls[i].iface = SNDRV_CTL_ELEM_IFACE_MIXER;
+		controls[i].name = control_name;
+		controls[i].info = snd_soc_dapm_info_pin_switch;
+		controls[i].get = snd_soc_dapm_get_pin_switch;
+		controls[i].put = snd_soc_dapm_put_pin_switch;
+		controls[i].private_value = (unsigned long)strings[i];
+	}
+
+	card->controls = controls;
+	card->num_controls = nb_controls;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_of_parse_pin_switches);
+
 int snd_soc_of_get_slot_mask(struct device_node *np,
 			     const char *prop_name,
 			     unsigned int *mask)