[PATCH 2/3] ASoC: bdw-rt5650: channel constraint support

[Brent Lu <brent.lu@intel.com>]

BDW boards using this machine driver supports only 2 or 4-channel capture.
Implement a constraint to enforce it.

Signed-off-by: Brent Lu <brent.lu@intel.com>
---
 sound/soc/intel/boards/bdw-rt5650.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/sound/soc/intel/boards/bdw-rt5650.c b/sound/soc/intel/boards/bdw-rt5650.c
index af2f502..dd4f219 100644
--- a/sound/soc/intel/boards/bdw-rt5650.c
+++ b/sound/soc/intel/boards/bdw-rt5650.c
@@ -21,6 +21,9 @@
 
 #include "../../codecs/rt5645.h"
 
+#define DUAL_CHANNEL 2
+#define QUAD_CHANNEL 4
+
 struct bdw_rt5650_priv {
 	struct gpio_desc *gpio_hp_en;
 	struct snd_soc_component *component;
@@ -162,6 +165,36 @@ static int bdw_rt5650_rtd_init(struct snd_soc_pcm_runtime *rtd)
 }
 #endif
 
+static const unsigned int channels[] = {
+	DUAL_CHANNEL, QUAD_CHANNEL,
+};
+
+static const struct snd_pcm_hw_constraint_list constraints_channels = {
+	.count = ARRAY_SIZE(channels),
+	.list = channels,
+	.mask = 0,
+};
+
+static int bdw_fe_startup(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+
+	/*
+	 * On this platform for PCM device we support,
+	 * 2 or 4 channel capture
+	 */
+	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
+		snd_pcm_hw_constraint_list(runtime, 0,
+					   SNDRV_PCM_HW_PARAM_CHANNELS,
+					   &constraints_channels);
+
+	return 0;
+}
+
+static const struct snd_soc_ops bdw_rt5650_fe_ops = {
+	.startup = bdw_fe_startup,
+};
+
 static int bdw_rt5650_init(struct snd_soc_pcm_runtime *rtd)
 {
 	struct bdw_rt5650_priv *bdw_rt5650 =
@@ -234,6 +267,7 @@ static struct snd_soc_dai_link bdw_rt5650_dais[] = {
 		.name = "System PCM",
 		.stream_name = "System Playback",
 		.dynamic = 1,
+		.ops = &bdw_rt5650_fe_ops,
 #if !IS_ENABLED(CONFIG_SND_SOC_SOF_BROADWELL)
 		.init = bdw_rt5650_rtd_init,
 #endif
-- 
2.7.4