[PATCH v2 1/3] dt-bindings: spi: Add Nuvoton WPCM450 Flash Interface Unit (FIU)

["Jonathan Neuschäfer" <j.neuschaefer@gmx.net>]

The Flash Interface Unit (FIU) is the SPI flash controller in the
Nuvoton WPCM450 BMC SoC. It supports four chip selects, and direct
(memory-mapped) access to 16 MiB per chip. Larger flash chips can be
accessed by software-defined SPI transfers.

The FIU in newer NPCM7xx SoCs is not compatible with the WPCM450 FIU.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
---

v2:
- A few cleanups suggested by Krzysztof Kozlowski
- Simplify binding by making second reg item mandatory

v1:
- https://lore.kernel.org/lkml/20221105185911.1547847-4-j.neuschaefer@gmx.net/
---
 .../bindings/spi/nuvoton,wpcm450-fiu.yaml     | 66 +++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/nuvoton,wpcm450-fiu.yaml

diff --git a/Documentation/devicetree/bindings/spi/nuvoton,wpcm450-fiu.yaml b/Documentation/devicetree/bindings/spi/nuvoton,wpcm450-fiu.yaml
new file mode 100644
index 0000000000000..ef94803e75d90
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/nuvoton,wpcm450-fiu.yaml
@@ -0,0 +1,66 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/nuvoton,wpcm450-fiu.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Nuvoton WPCM450 Flash Interface Unit (FIU)
+
+maintainers:
+  - Jonathan Neuschäfer <j.neuschaefer@gmx.net>
+
+allOf:
+  - $ref: /schemas/spi/spi-controller.yaml#
+
+properties:
+  compatible:
+    const: nuvoton,wpcm450-fiu
+
+  reg:
+    items:
+      - description: FIU registers
+      - description: Memory-mapped flash contents
+
+  reg-names:
+    items:
+      - const: control
+      - const: memory
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  nuvoton,shm:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: a phandle to the SHM block (see ../arm/nuvoton,shm.yaml)
+
+required:
+  - compatible
+  - reg
+  - clocks
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/nuvoton,wpcm450-clk.h>
+    spi@c8000000 {
+      compatible = "nuvoton,wpcm450-fiu";
+      reg = <0xc8000000 0x1000>, <0xc0000000 0x4000000>;
+      #address-cells = <1>;
+      #size-cells = <0>;
+      reg-names = "control", "memory";
+      clocks = <&clk WPCM450_CLK_FIU>;
+      nuvoton,shm = <&shm>;
+
+      flash@0 {
+        compatible = "jedec,spi-nor";
+      };
+    };
+
+    shm: syscon@c8001000 {
+      compatible = "nuvoton,wpcm450-shm", "syscon";
+      reg = <0xc8001000 0x1000>;
+    };
--
2.35.1