Introduce Socionext F_OSPI SPI flash controller

Merge series from Kunihiko Hayashi <hayashi.kunihiko@socionext.com>:

This series adds dt-bindings and a driver for Socionext F_OSPI controller
for connecting an SPI Flash memory over up to 8-bit wide bus.
The controller supports up to 4 chip selects.

Documentation/devicetree/bindings/spi/socionext,f-ospi.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/socionext,f-ospi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Socionext F_OSPI controller
+
+description: |
+  The Socionext F_OSPI is a controller used to interface with flash
+  memories using the SPI communication interface.
+
+maintainers:
+  - Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
+
+allOf:
+  - $ref: spi-controller.yaml#
+
+properties:
+  compatible:
+    const: socionext,f-ospi
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  num-cs:
+    minimum: 1
+    maximum: 4
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - "#address-cells"
+  - "#size-cells"
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    ospi0: spi@80000000 {
+        compatible = "socionext,f-ospi";
+        reg = <0x80000000 0x1000>;
+        clocks = <&clks 0>;
+        num-cs = <1>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        flash@0 {
+            compatible = "spansion,s25fl128s", "jedec,spi-nor";
+            reg = <0>;
+            spi-max-frequency = <50000000>;
+        };
+    };

drivers/spi/Kconfig

@@ -906,6 +906,15 @@ config SPI_SLAVE_MT27XX
 	  say Y or M here.If you are not sure, say N.
 	  SPI slave drivers for Mediatek MT27XX series ARM SoCs.
 
+config SPI_SN_F_OSPI
+	tristate "Socionext F_OSPI SPI flash controller"
+	depends on OF && HAS_IOMEM
+	depends on SPI_MEM
+	help
+	  This enables support for the Socionext F_OSPI controller
+	  for connecting an SPI Flash memory over up to 8-bit wide bus.
+	  It supports indirect access mode only.
+
 config SPI_SPRD
 	tristate "Spreadtrum SPI controller"
 	depends on ARCH_SPRD || COMPILE_TEST

drivers/spi/Makefile

@@ -121,6 +121,7 @@ obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
 obj-$(CONFIG_SPI_SH_SCI)		+= spi-sh-sci.o
 obj-$(CONFIG_SPI_SIFIVE)		+= spi-sifive.o
 obj-$(CONFIG_SPI_SLAVE_MT27XX)          += spi-slave-mt27xx.o
+obj-$(CONFIG_SPI_SN_F_OSPI)		+= spi-sn-f-ospi.o
 obj-$(CONFIG_SPI_SPRD)			+= spi-sprd.o
 obj-$(CONFIG_SPI_SPRD_ADI)		+= spi-sprd-adi.o
 obj-$(CONFIG_SPI_STM32) 		+= spi-stm32.o