Add PWM-DAC audio support for StarFive JH7110

Merge series from Hal Feng <hal.feng@starfivetech.com>:

This patchset adds PWM-DAC audio support for the StarFive JH7110 SoC.
The PWM-DAC module does not require a hardware codec, but a dummy codec is
needed for the driver. The dummy spdif codec driver, which is already
upstream, is compatible with the one which JH7110 PWM-DAC needed. So we
use it as the dummy codec driver for the JH7110 PWM-DAC module.

Documentation/devicetree/bindings/sound/starfive,jh7110-pwmdac.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/sound/starfive,jh7110-pwmdac.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: StarFive JH7110 PWM-DAC Controller
+
+description:
+  The PWM-DAC Controller uses PWM square wave generators plus RC filters to
+  form a DAC for audio play in StarFive JH7110 SoC. This audio play controller
+  supports 16 bit audio format, up to 48K sampling frequency, up to left and
+  right dual channels.
+
+maintainers:
+  - Hal Feng <hal.feng@starfivetech.com>
+
+allOf:
+  - $ref: dai-common.yaml#
+
+properties:
+  compatible:
+    const: starfive,jh7110-pwmdac
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: PWMDAC APB
+      - description: PWMDAC CORE
+
+  clock-names:
+    items:
+      - const: apb
+      - const: core
+
+  resets:
+    maxItems: 1
+    description: PWMDAC APB
+
+  dmas:
+    maxItems: 1
+    description: TX DMA Channel
+
+  dma-names:
+    const: tx
+
+  "#sound-dai-cells":
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - resets
+  - dmas
+  - dma-names
+  - "#sound-dai-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    pwmdac@100b0000 {
+        compatible = "starfive,jh7110-pwmdac";
+        reg = <0x100b0000 0x1000>;
+        clocks = <&syscrg 157>,
+                 <&syscrg 158>;
+        clock-names = "apb", "core";
+        resets = <&syscrg 96>;
+        dmas = <&dma 22>;
+        dma-names = "tx";
+        #sound-dai-cells = <0>;
+    };

MAINTAINERS

@@ -20466,6 +20466,13 @@ S:	Supported
 F:	Documentation/devicetree/bindings/clock/starfive,jh7110-pll.yaml
 F:	drivers/clk/starfive/clk-starfive-jh7110-pll.c
 
+STARFIVE JH7110 PWMDAC DRIVER
+M:	Hal Feng <hal.feng@starfivetech.com>
+M:	Xingyu Wu <xingyu.wu@starfivetech.com>
+S:	Supported
+F:	Documentation/devicetree/bindings/sound/starfive,jh7110-pwmdac.yaml
+F:	sound/soc/starfive/jh7110_pwmdac.c
+
 STARFIVE JH7110 SYSCON
 M:	William Qiu <william.qiu@starfivetech.com>
 M:	Xingyu Wu <xingyu.wu@starfivetech.com>

sound/soc/starfive/Kconfig

@@ -7,6 +7,15 @@ config SND_SOC_STARFIVE
 	  the Starfive SoCs' Audio interfaces. You will also need to
 	  select the audio interfaces to support below.
 
+config SND_SOC_JH7110_PWMDAC
+	tristate "JH7110 PWM-DAC device driver"
+	depends on HAVE_CLK && SND_SOC_STARFIVE
+	select SND_SOC_GENERIC_DMAENGINE_PCM
+	select SND_SOC_SPDIF
+	help
+	 Say Y or M if you want to add support for StarFive JH7110
+	 PWM-DAC driver.
+
 config SND_SOC_JH7110_TDM
 	tristate "JH7110 TDM device driver"
 	depends on HAVE_CLK && SND_SOC_STARFIVE

sound/soc/starfive/Makefile

 # StarFive Platform Support
+obj-$(CONFIG_SND_SOC_JH7110_PWMDAC) += jh7110_pwmdac.o
 obj-$(CONFIG_SND_SOC_JH7110_TDM) += jh7110_tdm.o