[RFC V4 PATCH 13/19] ALSA: mixer_audient: Add enumerated controls

[Christian Ruppert <arc@gmx.li>]

From: Will Porter <mrwillporter@gmail.com>

The iD14 has selectors with a fixed set of device values: output
routing, mono mode, the iD key function, talkback source and the
digital input mode. Add an enumerated control type with a value list.

The item list has one item more than the values. A put cannot select
it. A get shows it for a device value outside the list, so a value set
by other means stays visible as such, not as a wrong item, and for a
write-only value that no write has confirmed.

Signed-off-by: Will Porter <mrwillporter@gmail.com>
---
 sound/usb/mixer_audient.c | 126 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 126 insertions(+)

diff --git a/sound/usb/mixer_audient.c b/sound/usb/mixer_audient.c
index 771a45cf6b45..2e1d4809645f 100644
--- a/sound/usb/mixer_audient.c
+++ b/sound/usb/mixer_audient.c
@@ -42,6 +42,25 @@ static const DECLARE_TLV_DB_MINMAX_MUTE(snd_audient_tlv_mixer, -12800, 600);
 #define SND_AUDIENT_CTYPE_FLAGS_GET_BROKEN	BIT(2)
 #define SND_AUDIENT_CTYPE_FLAGS_CACHE		BIT(3)
 
+/*
+ * An enumerated control: item i sends values[i]. A get of a device value
+ * outside the list returns -EIO; it does not show a wrong item.
+ */
+struct snd_audient_enum {
+	const char *const *texts;
+	const u32 *values;
+	unsigned int items;
+};
+
+#define SND_AUDIENT_ENUM(name, texts_, ...)				\
+	static const u32 name##_values[] = { __VA_ARGS__ };		\
+	static const struct snd_audient_enum name = {			\
+		.texts = texts_,					\
+		.values = name##_values,				\
+		.items = ARRAY_SIZE(name##_values),			\
+	};								\
+	static_assert(ARRAY_SIZE(texts_) == ARRAY_SIZE(name##_values))
+
 static const struct snd_audient_ctrl_type {
 	snd_ctl_elem_type_t type;
 	unsigned long flags;
@@ -54,6 +73,7 @@ static const struct snd_audient_ctrl_type {
 	} max;		/* for booleans holds physical int value for true */
 	u32 init;	/* hardware and cache are initialized to this value */
 	unsigned int res;	/* integers: device units per control step, 0 = 1 */
+	const struct snd_audient_enum *enumeration;
 	const unsigned int *tlv;
 	u8 unit;
 	u8 sel;
@@ -537,12 +557,114 @@ static int snd_ctl_audient_integer_set(struct snd_kcontrol *kctl,
 	return changed;
 }
 
+static unsigned int snd_audient_enum_item(const struct snd_audient_enum *e,
+					  u32 value)
+{
+	unsigned int item;
+
+	for (item = 0; item < e->items; item++)
+		if (e->values[item] == value)
+			break;
+
+	return item;	/* e->items: not in the list */
+}
+
+static int snd_ctl_audient_enum_get(struct snd_kcontrol *kctl,
+				    struct snd_ctl_elem_value *ctl_val)
+{
+	struct usb_mixer_elem_info *const elem = snd_kcontrol_chip(kctl);
+	struct usb_mixer_interface *const mixer = elem->head.mixer;
+
+	const unsigned int nchan = snd_audient_kctl_channels(kctl);
+	const unsigned int hwchan = snd_audient_kctl_hwchannels(kctl);
+	const struct snd_audient_ctrl_type *const ctype
+						= snd_audient_kctl_type(kctl);
+	const u8 base = snd_audient_kctl_cidxoffs(kctl);
+
+	unsigned int i;
+
+	CLASS(snd_usb_lock, pm)(mixer->chip);
+	if (pm.err < 0)
+		return pm.err;
+	/* serializes the transfers and the cache, also between gets */
+	guard(mutex)(&mixer->lock);
+
+	for (i = 0; i < hwchan; i++) {
+		unsigned int item;
+		u32 val;
+		int ret;
+
+		ret = snd_audient_raw_get_one(elem, ctype, base + i, &val);
+		if (ret == -ENODATA)	/* unknown write-only value: init */
+			val = ctype->init;
+		else if (ret < 0)
+			return ret;
+
+		item = snd_audient_enum_item(ctype->enumeration, val);
+		if (item >= ctype->enumeration->items)
+			return -EIO;
+
+		ctl_val->value.enumerated.item[i] = item;
+	}
+
+	for (; i < nchan; i++)
+		ctl_val->value.enumerated.item[i] = 0;
+
+	return 0;
+}
+
+static int snd_ctl_audient_enum_set(struct snd_kcontrol *kctl,
+				    struct snd_ctl_elem_value *ctl_val)
+{
+	struct usb_mixer_elem_info *const elem = snd_kcontrol_chip(kctl);
+	struct usb_mixer_interface *const mixer = elem->head.mixer;
+
+	const unsigned int hwchan = snd_audient_kctl_hwchannels(kctl);
+	const struct snd_audient_ctrl_type *const ctype
+						= snd_audient_kctl_type(kctl);
+	const struct snd_audient_enum *const e = ctype->enumeration;
+	const u8 base = snd_audient_kctl_cidxoffs(kctl);
+
+	unsigned int i;
+	int changed = 0;
+
+	for (i = 0; i < hwchan; i++)
+		if (ctl_val->value.enumerated.item[i] >= e->items)
+			return -EINVAL;
+
+	CLASS(snd_usb_lock, pm)(mixer->chip);
+	if (pm.err < 0)
+		return pm.err;
+	/* serializes the transfers and the cache, also between gets */
+	guard(mutex)(&mixer->lock);
+
+	for (i = 0; i < hwchan; i++) {
+		const unsigned int item = ctl_val->value.enumerated.item[i];
+		int ret;
+
+		ret = snd_audient_raw_set_one(elem, ctype, base + i,
+					      e->values[item], false);
+		if (ret < 0)
+			return ret;
+
+		if (ret)
+			changed = 1;
+	}
+
+	return changed;
+}
+
 static int snd_ctl_audient_info(struct snd_kcontrol *kctl,
 			    struct snd_ctl_elem_info *uinfo)
 {
 	const struct snd_audient_ctrl_type *const ctype
 						= snd_audient_kctl_type(kctl);
 
+	if (ctype->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED)
+		return snd_ctl_enum_info(uinfo, snd_audient_kctl_channels(kctl),
+					 ctype->enumeration->items,
+					 ctype->enumeration->texts);
+
 	uinfo->type = ctype->type;
 	uinfo->count = snd_audient_kctl_channels(kctl);
 
@@ -590,6 +712,10 @@ static int snd_audient_add_ctrl(struct usb_mixer_interface *mixer,
 		knew.get = snd_ctl_audient_boolean_get;
 		knew.put = snd_ctl_audient_boolean_set;
 		break;
+	case SNDRV_CTL_ELEM_TYPE_ENUMERATED:
+		knew.get = snd_ctl_audient_enum_get;
+		knew.put = snd_ctl_audient_enum_set;
+		break;
 	default:
 		return -EINVAL;
 	}
-- 
2.56.1