#!/usr/bin/env python3

#
# This file is part of LiteX-Boards.
#
# Copyright (c) 2015-2020 Florent Kermarrec <florent@enjoy-digital.fr>
# SPDX-License-Identifier: BSD-2-Clause

import os
import argparse

from migen import *
from migen.genlib.resetsync import AsyncResetSynchronizer

from litex.build.io import DDROutput

from litex_boards.platforms import de0nano

from litex.soc.cores.clock import CycloneIVPLL
from litex.soc.integration.soc_core import *
from litex.soc.integration.builder import *
from litex.soc.cores.led import LedChaser

from litedram.modules import IS42S16160
from litedram.phy import GENSDRPHY, HalfRateGENSDRPHY

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

class _CRG(Module):
    def __init__(self, platform, sys_clk_freq, sdram_rate="1:1"):
        self.rst = Signal()
        self.clock_domains.cd_sys    = ClockDomain()
        if sdram_rate == "1:2":
            self.clock_domains.cd_sys2x    = ClockDomain()
            self.clock_domains.cd_sys2x_ps = ClockDomain(reset_less=True)
        else:
            self.clock_domains.cd_sys_ps = ClockDomain(reset_less=True)

        # # #

        # Clk / Rst
        clk50 = platform.request("clk50")

        # PLL
        self.submodules.pll = pll = CycloneIVPLL(speedgrade="-6")
        self.comb += pll.reset.eq(self.rst)
        pll.register_clkin(clk50, 50e6)
        pll.create_clkout(self.cd_sys,    sys_clk_freq)
        if sdram_rate == "1:2":
            pll.create_clkout(self.cd_sys2x,    2*sys_clk_freq)
            pll.create_clkout(self.cd_sys2x_ps, 2*sys_clk_freq, phase=180)  # Idealy 90° but needs to be increased.
        else:
            pll.create_clkout(self.cd_sys_ps, sys_clk_freq, phase=90)

        # SDRAM clock
        sdram_clk = ClockSignal("sys2x_ps" if sdram_rate == "1:2" else "sys_ps")
        self.specials += DDROutput(1, 0, platform.request("sdram_clock"), sdram_clk)

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

class BaseSoC(SoCCore):
    def __init__(self, sys_clk_freq=int(50e6), sdram_rate="1:1", **kwargs):
        platform = de0nano.Platform()

        # SoCCore ----------------------------------------------------------------------------------
        SoCCore.__init__(self, platform, sys_clk_freq,
            ident          = "LiteX SoC on DE0-Nano",
            ident_version  = True,
            **kwargs)

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

        # SDR SDRAM --------------------------------------------------------------------------------
        if not self.integrated_main_ram_size:
            sdrphy_cls = HalfRateGENSDRPHY if sdram_rate == "1:2" else GENSDRPHY
            self.submodules.sdrphy = sdrphy_cls(platform.request("sdram"), sys_clk_freq)
            self.add_sdram("sdram",
                phy           = self.sdrphy,
                module        = IS42S16160(sys_clk_freq, sdram_rate),
                l2_cache_size = kwargs.get("l2_size", 8192)
            )

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

# Build --------------------------------------------------------------------------------------------

def main():
    parser = argparse.ArgumentParser(description="LiteX SoC on DE0-Nano")
    parser.add_argument("--build",        action="store_true", help="Build bitstream")
    parser.add_argument("--load",         action="store_true", help="Load bitstream")
    parser.add_argument("--sys-clk-freq", default=50e6,        help="System clock frequency (default: 50MHz)")
    parser.add_argument("--sdram-rate",   default="1:1",       help="SDRAM Rate: 1:1 Full Rate (default), 1:2 Half Rate")
    builder_args(parser)
    soc_core_args(parser)
    args = parser.parse_args()

    soc = BaseSoC(
        sys_clk_freq = int(float(args.sys_clk_freq)),
        sdram_rate   = args.sdram_rate,
        **soc_core_argdict(args)
    )
    builder = Builder(soc, **builder_argdict(args))
    builder.build(run=args.build)

    if args.load:
        prog = soc.platform.create_programmer()
        prog.load_bitstream(os.path.join(builder.gateware_dir, soc.build_name + ".sof"))

if __name__ == "__main__":
    main()