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| -rw-r--r-- | Documentation/devicetree/bindings/mips/img/xilfpga.txt | 83 |
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diff --git a/Documentation/devicetree/bindings/mips/img/xilfpga.txt b/Documentation/devicetree/bindings/mips/img/xilfpga.txt new file mode 100644 index 000000000000..57e7ee942166 --- /dev/null +++ b/Documentation/devicetree/bindings/mips/img/xilfpga.txt @@ -0,0 +1,83 @@ +Imagination University Program MIPSfpga +======================================= + +Under the Imagination University Program, a microAptiv UP core has been +released for academic usage. + +As we are dealing with a MIPS core instantiated on an FPGA, specifications +are fluid and can be varied in RTL. + +This binding document is provided as baseline guidance for the example +project provided by IMG. + +The example project runs on the Nexys4DDR board by Digilent powered by +the ARTIX-7 FPGA by Xilinx. + +Relevant details about the example project and the Nexys4DDR board: + +- microAptiv UP core m14Kc +- 50MHz clock speed +- 128Mbyte DDR RAM at 0x0000_0000 +- 8Kbyte RAM at 0x1000_0000 +- axi_intc at 0x1020_0000 +- axi_uart16550 at 0x1040_0000 +- axi_gpio at 0x1060_0000 +- axi_i2c at 0x10A0_0000 +- custom_gpio at 0x10C0_0000 +- axi_ethernetlite at 0x10E0_0000 +- 8Kbyte BootRAM at 0x1FC0_0000 + +Required properties: +-------------------- + - compatible: Must include "digilent,nexys4ddr","img,xilfpga". + +CPU nodes: +---------- +A "cpus" node is required. Required properties: + - #address-cells: Must be 1. + - #size-cells: Must be 0. +A CPU sub-node is also required for at least CPU 0. Required properties: + - device_type: Must be "cpu". + - compatible: Must be "mips,m14Kc". + - reg: Must be <0>. + - clocks: phandle to ext clock for fixed-clock received by MIPS core. + +Example: + + compatible = "img,xilfpga","digilent,nexys4ddr"; + cpus { + #address-cells = <1>; + #size-cells = <0>; + + cpu0: cpu@0 { + device_type = "cpu"; + compatible = "mips,m14Kc"; + reg = <0>; + clocks = <&ext>; + }; + }; + + ext: ext { + compatible = "fixed-clock"; + #clock-cells = <0>; + clock-frequency = <50000000>; + }; + +Boot protocol: +-------------- + +The BootRAM is a writeable "RAM" in FPGA at 0x1FC0_0000. +This is for easy reprogrammibility via JTAG. + +The BootRAM initializes the cache and the axi_uart peripheral. + +DDR initialization is already handled by a HW IP block. + +When the example project bitstream is loaded, the cpu_reset button +needs to be pressed. + +The bootram initializes the cache and axi_uart. +Then outputs MIPSFPGA\n\r on the serial port on the Nexys4DDR board. + +At this point, the board is ready to load the Linux kernel +vmlinux file via JTAG. |