dt-bindings: fpga: xlnx,fpga-selectmap: add DT schema

Document the SelectMAP interface of Xilinx 7 series FPGA.

Signed-off-by: Charles Perry <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Xu Yilun <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Xu Yilun <[e-mail]>

Documentation/devicetree/bindings/fpga/xlnx,fpga-selectmap.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/fpga/xlnx,fpga-selectmap.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Xilinx SelectMAP FPGA interface
+
+maintainers:
+  - Charles Perry <[e-mail]>
+
+description: |
+  Xilinx 7 Series FPGAs support a method of loading the bitstream over a
+  parallel port named the SelectMAP interface in the documentation. Only
+  the x8 mode is supported where data is loaded at one byte per rising edge of
+  the clock, with the MSB of each byte presented to the D0 pin.
+
+  Datasheets:
+    https://www.xilinx.com/support/documentation/user_guides/ug470_7Series_Config.pdf
+
+allOf:
+  - $ref: /schemas/memory-controllers/mc-peripheral-props.yaml#
+
+properties:
+  compatible:
+    enum:
+      - xlnx,fpga-xc7s-selectmap
+      - xlnx,fpga-xc7a-selectmap
+      - xlnx,fpga-xc7k-selectmap
+      - xlnx,fpga-xc7v-selectmap
+
+  reg:
+    description:
+      At least 1 byte of memory mapped IO
+    maxItems: 1
+
+  prog-gpios:
+    description:
+      config pin (referred to as PROGRAM_B in the manual)
+    maxItems: 1
+
+  done-gpios:
+    description:
+      config status pin (referred to as DONE in the manual)
+    maxItems: 1
+
+  init-gpios:
+    description:
+      initialization status and configuration error pin
+      (referred to as INIT_B in the manual)
+    maxItems: 1
+
+  csi-gpios:
+    description:
+      chip select pin (referred to as CSI_B in the manual)
+      Optional gpio for if the bus controller does not provide a chip select.
+    maxItems: 1
+
+  rdwr-gpios:
+    description:
+      read/write select pin (referred to as RDWR_B in the manual)
+      Optional gpio for if the bus controller does not provide this pin.
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - prog-gpios
+  - done-gpios
+  - init-gpios
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    fpga-mgr@8000000 {
+      compatible = "xlnx,fpga-xc7s-selectmap";
+      reg = <0x8000000 0x4>;
+      prog-gpios = <&gpio5 5 GPIO_ACTIVE_LOW>;
+      init-gpios = <&gpio5 8 GPIO_ACTIVE_LOW>;
+      done-gpios = <&gpio2 30 GPIO_ACTIVE_HIGH>;
+      csi-gpios = <&gpio3 19 GPIO_ACTIVE_LOW>;
+      rdwr-gpios = <&gpio3 10 GPIO_ACTIVE_LOW>;
+    };
+...