Nuvoton WPCM450 FIU SPI flash controller

Merge series from Jonathan Neuschäfer <j.neuschaefer@gmx.net>:

This patchset adds DT bindings and a driver for the Flash Interface Unit
(FIU), 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 existing NPCM7xx FIU driver is sufficitently incompatible with the
WPCM450 FIU that I decided to write a new driver.

Documentation/devicetree/bindings/spi/nuvoton,wpcm450-fiu.yaml

+# 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>;
+    };

drivers/spi/Kconfig

@@ -635,6 +635,17 @@ config SPI_MTK_SNFI
 	  is implemented as a SPI-MEM controller with pipelined ECC
 	  capcability.
 
+config SPI_WPCM_FIU
+	tristate "Nuvoton WPCM450 Flash Interface Unit"
+	depends on ARCH_NPCM || COMPILE_TEST
+	select REGMAP
+	help
+	  This enables support got the Flash Interface Unit SPI controller
+	  present in the Nuvoton WPCM450 SoC.
+
+	  This driver does not support generic SPI. The implementation only
+	  supports the spi-mem interface.
+
 config SPI_NPCM_FIU
 	tristate "Nuvoton NPCM FLASH Interface Unit"
 	depends on ARCH_NPCM || COMPILE_TEST

drivers/spi/Makefile

@@ -83,6 +83,7 @@ obj-$(CONFIG_SPI_MTK_NOR)		+= spi-mtk-nor.o
 obj-$(CONFIG_SPI_MTK_SNFI)		+= spi-mtk-snfi.o
 obj-$(CONFIG_SPI_MXIC)			+= spi-mxic.o
 obj-$(CONFIG_SPI_MXS)			+= spi-mxs.o
+obj-$(CONFIG_SPI_WPCM_FIU)		+= spi-wpcm-fiu.o
 obj-$(CONFIG_SPI_NPCM_FIU)		+= spi-npcm-fiu.o
 obj-$(CONFIG_SPI_NPCM_PSPI)		+= spi-npcm-pspi.o
 obj-$(CONFIG_SPI_NXP_FLEXSPI)		+= spi-nxp-fspi.o