ASoC: imx-pcm-rpmsg: Add platform driver for audio base on rpmsg

Platform driver based on rpmsg is the interface for sending and
receiving rpmsg to and from M core. It will tell the Cortex-M core
sound format/rate/channel, where is the data buffer, where is
the period size, when to start, when to stop and when suspend
or resume happen, each this behavior there is defined rpmsg
command.

Especially we designed the low power audio case, that is to
allocate a large buffer and fill the data, then Cortex-A core can go
to sleep mode, Cortex-M core continue to play the sound, when the
buffer is consumed, Cortex-M core will trigger the Cortex-A core to
wake up.
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Link: https://lore.kernel.org/r/1615516725-4975-6-git-send-email-shengjiu.wang@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/fsl/Kconfig

@@ -133,6 +133,11 @@ config SND_SOC_IMX_AUDIO_RPMSG
 	tristate
 	depends on RPMSG
 
+config SND_SOC_IMX_PCM_RPMSG
+	tristate
+	depends on SND_SOC_IMX_AUDIO_RPMSG
+	select SND_SOC_GENERIC_DMAENGINE_PCM
+
 config SND_SOC_IMX_AUDMUX
 	tristate "Digital Audio Mux module support"
 	help

sound/soc/fsl/Makefile

@@ -61,6 +61,7 @@ obj-$(CONFIG_SND_SOC_IMX_AUDMUX) += snd-soc-imx-audmux.o
 obj-$(CONFIG_SND_SOC_IMX_PCM_FIQ) += imx-pcm-fiq.o
 obj-$(CONFIG_SND_SOC_IMX_PCM_DMA) += imx-pcm-dma.o
 obj-$(CONFIG_SND_SOC_IMX_AUDIO_RPMSG) += imx-audio-rpmsg.o
+obj-$(CONFIG_SND_SOC_IMX_PCM_RPMSG) += imx-pcm-rpmsg.o
 
 # i.MX Machine Support
 snd-soc-eukrea-tlv320-objs := eukrea-tlv320.o