dt-bindings: mmc: Add Sparx5 SDHCI controller bindings

The Sparx5 SDHCI controller is based on the Designware controller IP.
Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com>
Link: https://lore.kernel.org/r/20200825081357.32354-2-lars.povlsen@microchip.com
Link: https://lore.kernel.org/r/20200826130106.22889-1-lars.povlsen@microchip.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/microchip,dw-sparx5-sdhci.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mmc/microchip,dw-sparx5-sdhci.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip Sparx5 Mobile Storage Host Controller Binding
+
+allOf:
+  - $ref: "mmc-controller.yaml"
+
+maintainers:
+  - Lars Povlsen <lars.povlsen@microchip.com>
+
+# Everything else is described in the common file
+properties:
+  compatible:
+    const: microchip,dw-sparx5-sdhci
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+    description:
+      Handle to "core" clock for the sdhci controller.
+
+  clock-names:
+    items:
+      - const: core
+
+  microchip,clock-delay:
+    description: Delay clock to card to meet setup time requirements.
+      Each step increase by 1.25ns.
+    $ref: "/schemas/types.yaml#/definitions/uint32"
+    minimum: 1
+    maximum: 15
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/clock/microchip,sparx5.h>
+    sdhci0: mmc@600800000 {
+        compatible = "microchip,dw-sparx5-sdhci";
+        reg = <0x00800000 0x1000>;
+        pinctrl-0 = <&emmc_pins>;
+        pinctrl-names = "default";
+        clocks = <&clks CLK_ID_AUX1>;
+        clock-names = "core";
+        assigned-clocks = <&clks CLK_ID_AUX1>;
+        assigned-clock-rates = <800000000>;
+        interrupts = <GIC_SPI 4 IRQ_TYPE_LEVEL_HIGH>;
+        bus-width = <8>;
+        microchip,clock-delay = <10>;
+    };