ASoC: Add MICFIL SoC Digital Audio Interface driver.

Add Digital Audio Interface driver that convers PDM bitstream to PCM
format.

Features:
- Fixed filtering characteristics for audio application.
- Full or partial set of channels operation with individual enable control.
- Programmable PDM clock generator.
- Programmable decimation rate.
- 16-bit signed output result.
- Overall stopband attenuation more than 80dB.
- Overall passband ripple less than 0.2dB.
Signed-off-by: Cosmin-Gabriel Samoila <cosmin.samoila@nxp.com>
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/fsl/Kconfig

@@ -57,6 +57,15 @@ config SND_SOC_FSL_ESAI
 	  This option is only useful for out-of-tree drivers since
 	  in-tree drivers select it automatically.
 
+config SND_SOC_FSL_MICFIL
+	tristate "Pulse Density Modulation Microphone Interface (MICFIL) module support"
+	select REGMAP_MMIO
+	select SND_SOC_IMX_PCM_DMA if SND_IMX_SOC != n
+	select SND_SOC_GENERIC_DMAENGINE_PCM
+	help
+	  Say Y if you want to add Pulse Density Modulation microphone
+	  interface (MICFIL) support for NXP.
+
 config SND_SOC_FSL_UTILS
 	tristate
 

sound/soc/fsl/Makefile

@@ -19,6 +19,7 @@ snd-soc-fsl-ssi-y := fsl_ssi.o
 snd-soc-fsl-ssi-$(CONFIG_DEBUG_FS) += fsl_ssi_dbg.o
 snd-soc-fsl-spdif-objs := fsl_spdif.o
 snd-soc-fsl-esai-objs := fsl_esai.o
+snd-soc-fsl-micfil-objs := fsl_micfil.o
 snd-soc-fsl-utils-objs := fsl_utils.o
 snd-soc-fsl-dma-objs := fsl_dma.o
 obj-$(CONFIG_SND_SOC_FSL_ASOC_CARD) += snd-soc-fsl-asoc-card.o
@@ -27,6 +28,7 @@ obj-$(CONFIG_SND_SOC_FSL_SAI) += snd-soc-fsl-sai.o
 obj-$(CONFIG_SND_SOC_FSL_SSI) += snd-soc-fsl-ssi.o
 obj-$(CONFIG_SND_SOC_FSL_SPDIF) += snd-soc-fsl-spdif.o
 obj-$(CONFIG_SND_SOC_FSL_ESAI) += snd-soc-fsl-esai.o
+obj-$(CONFIG_SND_SOC_FSL_MICFIL) += snd-soc-fsl-micfil.o
 obj-$(CONFIG_SND_SOC_FSL_UTILS) += snd-soc-fsl-utils.o
 obj-$(CONFIG_SND_SOC_POWERPC_DMA) += snd-soc-fsl-dma.o