spi: dt-bindings: nuvoton,npcm-pspi: Convert to DT schema

Convert the Nuvoton NPCM PSPI binding to DT schema format.

Also update the binding to fix shortcoming:
* Drop clock-frequency property: it is never read in the NPCM PSPI
driver and has no effect.

Signed-off-by: Tomer Maimon <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/spi/nuvoton,npcm-pspi.txt

···
-Nuvoton NPCM Peripheral Serial Peripheral Interface(PSPI) controller driver
-
-Nuvoton NPCM7xx SOC support two PSPI channels.
-
-Required properties:
- - compatible : "nuvoton,npcm750-pspi" for Poleg NPCM7XX.
-				"nuvoton,npcm845-pspi" for Arbel NPCM8XX.
- - #address-cells : should be 1. see spi-bus.txt
- - #size-cells : should be 0. see spi-bus.txt
- - specifies physical base address and size of the register.
- - interrupts : contain PSPI interrupt.
- - clocks : phandle of PSPI reference clock.
- - clock-names: Should be "clk_apb5".
- - pinctrl-names : a pinctrl state named "default" must be defined.
- - pinctrl-0 : phandle referencing pin configuration of the device.
- - resets : phandle to the reset control for this device.
- - cs-gpios: Specifies the gpio pins to be used for chipselects.
-            See: Documentation/devicetree/bindings/spi/spi-bus.txt
-
-Optional properties:
-- clock-frequency : Input clock frequency to the PSPI block in Hz.
-		    Default is 25000000 Hz.
-
-spi0: spi@f0200000 {
-	compatible = "nuvoton,npcm750-pspi";
-	reg = <0xf0200000 0x1000>;
-	pinctrl-names = "default";
-	pinctrl-0 = <&pspi1_pins>;
-	#address-cells = <1>;
-	#size-cells = <0>;
-	interrupts = <GIC_SPI 31 IRQ_TYPE_LEVEL_HIGH>;
-	clocks = <&clk NPCM7XX_CLK_APB5>;
-	clock-names = "clk_apb5";
-	resets = <&rstc NPCM7XX_RESET_IPSRST2 NPCM7XX_RESET_PSPI1>
-	cs-gpios = <&gpio6 11 GPIO_ACTIVE_LOW>;
-};

Documentation/devicetree/bindings/spi/nuvoton,npcm-pspi.yaml

···
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/nuvoton,npcm-pspi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Nuvoton NPCM Peripheral SPI (PSPI) Controller
+
+maintainers:
+  - Tomer Maimon <[e-mail]>
+
+allOf:
+  - $ref: spi-controller.yaml#
+
+description:
+  Nuvoton NPCM Peripheral Serial Peripheral Interface (PSPI) controller.
+  Nuvoton NPCM7xx SOC supports two PSPI channels.
+  Nuvoton NPCM8xx SOC support one PSPI channel.
+
+properties:
+  compatible:
+    enum:
+      - nuvoton,npcm750-pspi # Poleg NPCM7XX
+      - nuvoton,npcm845-pspi # Arbel NPCM8XX
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+    description: PSPI reference clock.
+
+  clock-names:
+    items:
+      - const: clk_apb5
+
+  resets:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+  - resets
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/nuvoton,npcm7xx-clock.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/reset/nuvoton,npcm7xx-reset.h>
+    #include "dt-bindings/gpio/gpio.h"
+    spi0: spi@f0200000 {
+        compatible = "nuvoton,npcm750-pspi";
+        reg = <0xf0200000 0x1000>;
+        pinctrl-names = "default";
+        pinctrl-0 = <&pspi1_pins>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+        interrupts = <GIC_SPI 31 IRQ_TYPE_LEVEL_HIGH>;
+        clocks = <&clk NPCM7XX_CLK_APB5>;
+        clock-names = "clk_apb5";
+        resets = <&rstc NPCM7XX_RESET_IPSRST2 NPCM7XX_RESET_PSPI1>;
+        cs-gpios = <&gpio6 11 GPIO_ACTIVE_LOW>;
+    };
+