FreeBSD/Linux Kernel Cross Reference
sys/contrib/device-tree/Bindings/fpga/xilinx-slave-serial.txt

     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>;
                    };
            };

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