#!/usr/bin/env python3

#
# This file is part of LiteX-Boards.
#
# Copyright (c) 2022 Alex Petrov <sysman@sysman.net>
# SPDX-License-Identifier: BSD-2-Clause

from migen import *

from litex.gen import *

from litex_boards.platforms import aliexpress_xc7k420t

from litex.soc.integration.soc_core import *
from litex.soc.integration.builder import *

from litex.soc.cores.clock import *
from litex.soc.cores.led import LedChaser

# CRG ----------------------------------------------------------------------------------------------

class _CRG(LiteXModule):
    def __init__(self, platform, sys_clk_freq):
        self.rst    = Signal()
        self.cd_sys = ClockDomain()

        # Clk / Rst.
        clk100 = platform.request("clk100")
        rst_n  = platform.request("user_btn_k3") # FIXME: Why not cpu_reset?

        # PLL.
        self.pll = pll = S7MMCM(speedgrade=-1)
        self.comb += pll.reset.eq(~rst_n | self.rst)
        pll.register_clkin(clk100, 100e6)
        pll.create_clkout(self.cd_sys,    sys_clk_freq)
        platform.add_false_path_constraints(self.cd_sys.clk, pll.clkin) # Ignore sys_clk to pll.clkin path created by SoC's rst.

# BaseSoC ------------------------------------------------------------------------------------------

class BaseSoC(SoCCore):
    def __init__(self, sys_clk_freq=100e6,
        with_led_chaser = True,
        with_spi_flash  = False,
        **kwargs):
        platform = aliexpress_xc7k420t.Platform()

        # CRG --------------------------------------------------------------------------------------
        self.crg = _CRG(platform, sys_clk_freq)

        # SoCCore ----------------------------------_-----------------------------------------------
        SoCCore.__init__(self, platform, sys_clk_freq, ident="LiteX SoC on AliExpress u420t", **kwargs)

	    # SPI Flash --------------------------------------------------------------------------------
        if with_spi_flash:
            from litespi.modules import N25Q256
            from litespi.opcodes import SpiNorFlashOpCodes as Codes
            self.add_spi_flash(mode="4x", module=W25Q256(Codes.READ_1_1_4))

        # Leds -------------------------------------------------------------------------------------
        if with_led_chaser:
            self.leds = LedChaser(
                pads         = platform.request_all("user_led"),
                sys_clk_freq = sys_clk_freq)

# Build --------------------------------------------------------------------------------------------  
def main():
    from litex.build.parser import LiteXArgumentParser
    parser = LiteXArgumentParser(platform=aliexpress_xc7k420t.Platform, description="LiteX SoC on AliExpress u420t.")
    parser.add_target_argument("--sys-clk-freq",   default=100e6, type=float, help="System clock frequency.")
    parser.add_target_argument("--with-spi-flash", action="store_true",       help="Enable SPI-mode flash support.")
    args = parser.parse_args()

    soc = BaseSoC(
        sys_clk_freq = args.sys_clk_freq,
        **parser.soc_argdict
    )
    builder = Builder(soc, **parser.builder_argdict)
    if args.build:
        builder.build(**parser.toolchain_argdict)

    if args.load:
        prog = soc.platform.create_programmer()
        prog.load_bitstream(obuilder.get_bitstream_filename(mode="sram"))

if __name__ == "__main__":
    main()