spi: rockchip-sfc: Bindings for Rockchip serial flash controller

Add bindings for the Rockchip serial flash controller. New device
specific parameter of rockchip,sfc-no-dma included in documentation.
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Signed-off-by: Jon Lin <jon.lin@rock-chips.com>
Tested-by: Peter Geis <pgwipeout@gmail.com>
Link: https://lore.kernel.org/r/20210812134546.31340-2-jon.lin@rock-chips.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/rockchip-sfc.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/rockchip-sfc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Rockchip Serial Flash Controller (SFC)
+
+maintainers:
+  - Heiko Stuebner <heiko@sntech.de>
+  - Chris Morgan <macromorgan@hotmail.com>
+
+allOf:
+  - $ref: spi-controller.yaml#
+
+properties:
+  compatible:
+    const: rockchip,sfc
+    description:
+      The rockchip sfc controller is a standalone IP with version register,
+      and the driver can handle all the feature difference inside the IP
+      depending on the version register.
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: Bus Clock
+      - description: Module Clock
+
+  clock-names:
+    items:
+      - const: clk_sfc
+      - const: hclk_sfc
+
+  power-domains:
+    maxItems: 1
+
+  rockchip,sfc-no-dma:
+    description: Disable DMA and utilize FIFO mode only
+    type: boolean
+
+patternProperties:
+  "^flash@[0-3]$":
+    type: object
+    properties:
+      reg:
+        minimum: 0
+        maximum: 3
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/px30-cru.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/power/px30-power.h>
+
+    sfc: spi@ff3a0000 {
+        compatible = "rockchip,sfc";
+        reg = <0xff3a0000 0x4000>;
+        interrupts = <GIC_SPI 56 IRQ_TYPE_LEVEL_HIGH>;
+        clocks = <&cru SCLK_SFC>, <&cru HCLK_SFC>;
+        clock-names = "clk_sfc", "hclk_sfc";
+        pinctrl-0 = <&sfc_clk &sfc_cs &sfc_bus2>;
+        pinctrl-names = "default";
+        power-domains = <&power PX30_PD_MMC_NAND>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        flash@0 {
+            compatible = "jedec,spi-nor";
+            reg = <0>;
+            spi-max-frequency = <108000000>;
+            spi-rx-bus-width = <2>;
+            spi-tx-bus-width = <2>;
+        };
+    };
+
+...