dt-bindings: spi: Add Cirrus EP93xx

Add YAML bindings for ep93xx SoC SPI.
Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>
Tested-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Documentation/devicetree/bindings/spi/cirrus,ep9301-spi.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/cirrus,ep9301-spi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: EP93xx SoC SPI controller
+
+maintainers:
+  - Alexander Sverdlin <alexander.sverdlin@gmail.com>
+  - Nikita Shubin <nikita.shubin@maquefel.me>
+
+allOf:
+  - $ref: spi-controller.yaml#
+
+properties:
+  compatible:
+    oneOf:
+      - const: cirrus,ep9301-spi
+      - items:
+          - enum:
+              - cirrus,ep9302-spi
+              - cirrus,ep9307-spi
+              - cirrus,ep9312-spi
+              - cirrus,ep9315-spi
+          - const: cirrus,ep9301-spi
+
+  reg:
+    items:
+      - description: SPI registers region
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: SPI Controller reference clock source
+
+  dmas:
+    items:
+      - description: rx DMA channel
+      - description: tx DMA channel
+
+  dma-names:
+    items:
+      - const: rx
+      - const: tx
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/clock/cirrus,ep9301-syscon.h>
+    spi@808a0000 {
+        compatible = "cirrus,ep9301-spi";
+        reg = <0x808a0000 0x18>;
+        interrupt-parent = <&vic1>;
+        interrupts = <21>;
+        clocks = <&syscon EP93XX_CLK_SPI>;
+        dmas = <&dma1 10 2>, <&dma1 10 1>;
+        dma-names = "rx", "tx";
+        cs-gpios = <&gpio5 2 GPIO_ACTIVE_HIGH>;
+    };