sound: soc: raspberrypi: RP1 Audio Out driver as an ASOC DAI

Only 48000Hz stereo 16-bit output is currently supported.

It requires some additional OF plumbing to connect it to a
"dummy" codec and generic sound card.

Signed-off-by: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com>

Author: njhollinghurst

arch/arm64/configs/bcm2712_defconfig

@@ -1155,6 +1155,7 @@ CONFIG_SND_PISOUND=m
 CONFIG_SND_DACBERRY400=m
 CONFIG_SND_DESIGNWARE_I2S=m
 CONFIG_SND_DESIGNWARE_PCM=y
+CONFIG_SND_RP1_AUDIO_OUT=m
 CONFIG_SND_SOC_AD193X_SPI=m
 CONFIG_SND_SOC_AD193X_I2C=m
 CONFIG_SND_SOC_ADAU1701=m

sound/soc/Kconfig

@@ -106,6 +106,7 @@ source "sound/soc/meson/Kconfig"
 source "sound/soc/mxs/Kconfig"
 source "sound/soc/pxa/Kconfig"
 source "sound/soc/qcom/Kconfig"
+source "sound/soc/raspberrypi/Kconfig"
 source "sound/soc/rockchip/Kconfig"
 source "sound/soc/samsung/Kconfig"
 source "sound/soc/sh/Kconfig"

sound/soc/Makefile

@@ -59,6 +59,7 @@ obj-$(CONFIG_SND_SOC)	+= mxs/
 obj-$(CONFIG_SND_SOC)	+= kirkwood/
 obj-$(CONFIG_SND_SOC)	+= pxa/
 obj-$(CONFIG_SND_SOC)	+= qcom/
+obj-$(CONFIG_SND_SOC)	+= raspberrypi/
 obj-$(CONFIG_SND_SOC)	+= rockchip/
 obj-$(CONFIG_SND_SOC)	+= samsung/
 obj-$(CONFIG_SND_SOC)	+= sh/

sound/soc/raspberrypi/Kconfig

@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config SND_RP1_AUDIO_OUT
+	tristate "PWM Audio Out from RP1"
+	select SND_SOC_GENERIC_DMAENGINE_PCM
+	select SND_SOC_SPDIF
+	help
+	 Say Y or M if you want to add support for PWM digital
+	 audio output from a Raspberry Pi 5, 500 or CM5.
+
+	 Output is from RP1 GPIOs pins 12 and 13 only, and additional
+	 components will be needed. It may be useful when HDMI, I2S
+	 or USB audio devices are unavailable, or for compatibility.

sound/soc/raspberrypi/Makefile

@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_SND_RP1_AUDIO_OUT) += rp1_aout.o