dt-bindings: Add devicetree bindings

Add snapshot of device tree bindings from keystone common kernel, branch
"android-mainline-keystone-qcom-release" at c4c12103f9c0 ("Snap for 9228065
from e32903b9a63bb558df8b803b076619c53c16baad to
android-mainline-keystone-qcom-release").

Change-Id: I7682079615cbd9f29340a5c1f2a1d84ec441a1f1
Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>

bindings/fpga/xilinx-slave-serial.txt

@@ -0,0 +1,51 @@
+Xilinx Slave Serial SPI FPGA Manager
+
+Xilinx Spartan-6 and 7 Series FPGAs support a method of loading the
+bitstream over what is referred to as "slave serial" interface.
+The slave serial link is not technically SPI, and might require extra
+circuits in order to play nicely with other SPI slaves on the same bus.
+
+See:
+- https://www.xilinx.com/support/documentation/user_guides/ug380.pdf
+- https://www.xilinx.com/support/documentation/user_guides/ug470_7Series_Config.pdf
+- https://www.xilinx.com/support/documentation/application_notes/xapp583-fpga-configuration.pdf
+
+Required properties:
+- compatible: should contain "xlnx,fpga-slave-serial"
+- reg: spi chip select of the FPGA
+- prog_b-gpios: config pin (referred to as PROGRAM_B in the manual)
+- done-gpios: config status pin (referred to as DONE in the manual)
+
+Optional properties:
+- init-b-gpios: initialization status and configuration error pin
+                (referred to as INIT_B in the manual)
+
+Example for full FPGA configuration:
+
+	fpga-region0 {
+		compatible = "fpga-region";
+		fpga-mgr = <&fpga_mgr_spi>;
+		#address-cells = <0x1>;
+		#size-cells = <0x1>;
+	};
+
+	spi1: spi@10680 {
+		compatible = "marvell,armada-xp-spi", "marvell,orion-spi";
+		pinctrl-0 = <&spi0_pins>;
+		pinctrl-names = "default";
+		#address-cells = <1>;
+		#size-cells = <0>;
+		cell-index = <1>;
+		interrupts = <92>;
+		clocks = <&coreclk 0>;
+
+		fpga_mgr_spi: fpga-mgr@0 {
+			compatible = "xlnx,fpga-slave-serial";
+			spi-max-frequency = <60000000>;
+			spi-cpha;
+			reg = <0>;
+			prog_b-gpios = <&gpio0 29 GPIO_ACTIVE_LOW>;
+			init-b-gpios = <&gpio0 28 GPIO_ACTIVE_LOW>;
+			done-gpios = <&gpio0 9 GPIO_ACTIVE_HIGH>;
+		};
+	};