ASoC: dt-bindings: Document Microchip's PDMC

Add DT bindings for the new Microchip PDMC embedded in sama7g5 SoCs.
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20220307122202.2251639-3-codrin.ciubotariu@microchip.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/microchip,pdmc.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/sound/microchip,pdmc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip Pulse Density Microphone Controller
+
+maintainers:
+  - Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
+
+description:
+  The Microchip Pulse Density Microphone Controller (PDMC) interfaces up to 4
+  digital microphones having Pulse Density Modulated (PDM) outputs.
+
+properties:
+  compatible:
+    const: microchip,sama7g5-pdmc
+
+  reg:
+    maxItems: 1
+
+  "#sound-dai-cells":
+    const: 0
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: Peripheral Bus Clock
+      - description: Generic Clock
+
+  clock-names:
+    items:
+      - const: pclk
+      - const: gclk
+
+  dmas:
+    description: RX DMA Channel
+    maxItems: 1
+
+  dma-names:
+    const: rx
+
+  microchip,mic-pos:
+    description: |
+      Position of PDM microphones on the DS line and the sampling edge (rising
+      or falling) of the CLK line. A microphone is represented as a pair of DS
+      line and the sampling edge. The first microphone is mapped to channel 0,
+      the second to channel 1, etc.
+    $ref: /schemas/types.yaml#/definitions/uint32-matrix
+    items:
+      items:
+        - description: value for DS line
+        - description: value for sampling edge
+      anyOf:
+        - enum:
+            - [0, 0]
+            - [0, 1]
+            - [1, 0]
+            - [1, 1]
+    minItems: 1
+    maxItems: 4
+    uniqueItems: true
+
+required:
+  - compatible
+  - reg
+  - "#sound-dai-cells"
+  - interrupts
+  - clocks
+  - clock-names
+  - dmas
+  - dma-names
+  - microchip,mic-pos
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/at91.h>
+    #include <dt-bindings/dma/at91.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/sound/microchip,pdmc.h>
+
+    pdmc: sound@e1608000 {
+        compatible = "microchip,sama7g5-pdmc";
+        reg = <0xe1608000 0x4000>;
+        #sound-dai-cells = <0>;
+        interrupts = <GIC_SPI 68 IRQ_TYPE_LEVEL_HIGH>;
+        dmas = <&dma0 AT91_XDMAC_DT_PERID(37)>;
+        dma-names = "rx";
+        clocks = <&pmc PMC_TYPE_PERIPHERAL 68>, <&pmc PMC_TYPE_GCK 68>;
+        clock-names = "pclk", "gclk";
+        microchip,mic-pos = <MCHP_PDMC_DS0 MCHP_PDMC_CLK_POSITIVE>,
+                            <MCHP_PDMC_DS0 MCHP_PDMC_CLK_NEGATIVE>,
+                            <MCHP_PDMC_DS1 MCHP_PDMC_CLK_POSITIVE>,
+                            <MCHP_PDMC_DS1 MCHP_PDMC_CLK_NEGATIVE>;
+    };

include/dt-bindings/sound/microchip,pdmc.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __DT_BINDINGS_MICROCHIP_PDMC_H__
+#define __DT_BINDINGS_MICROCHIP_PDMC_H__
+
+/* PDM microphone's pin placement */
+#define MCHP_PDMC_DS0 0
+#define MCHP_PDMC_DS1 1
+
+/* PDM microphone clock edge sampling */
+#define MCHP_PDMC_CLK_POSITIVE 0
+#define MCHP_PDMC_CLK_NEGATIVE 1
+
+#endif /* __DT_BINDINGS_MICROCHIP_PDMC_H__ */