#!/usr/bin/env python3

#
# This file is part of LiteX-Boards.
#
# Copyright (c) 2020 Gary Wong <gtw@gnu.org>
# SPDX-License-Identifier: BSD-2-Clause

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

from litex.gen import LiteXModule

from litex_boards.platforms import fpc_iii

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

from litedram.modules import IS43TR16256A
from litedram.phy import ECP5DDRPHY

from liteeth.phy.mii import LiteEthPHYMII

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

class _CRG(LiteXModule):
    def __init__(self, platform, sys_clk_freq):
        self.rst        = Signal()
        self.cd_init    = ClockDomain()
        self.cd_por     = ClockDomain()
        self.cd_sys     = ClockDomain()
        self.cd_sys2x   = ClockDomain()
        self.cd_sys2x_i = ClockDomain()

        self.stop  = Signal()
        self.reset = Signal()

        # Clk / Rst
        clk25 = platform.request("clk25")

        # Power on reset
        por_count = Signal(16, reset=2**16-1)
        por_done  = Signal()
        self.comb += self.cd_por.clk.eq(clk25)
        self.comb += por_done.eq(por_count == 0)
        self.sync.por += If(~por_done, por_count.eq(por_count - 1))

        # PLL
        sys2x_clk_ecsout = Signal()
        self.pll = pll = ECP5PLL()
        self.comb += pll.reset.eq(~por_done | self.rst)
        pll.register_clkin(clk25, 25e6)
        pll.create_clkout(self.cd_sys2x_i, 2*sys_clk_freq)
        pll.create_clkout(self.cd_init, 25e6)
        self.specials += [
            Instance("ECLKBRIDGECS",
                i_CLK0   = self.cd_sys2x_i.clk,
                i_SEL    = 0,
                o_ECSOUT = sys2x_clk_ecsout,
            ),
            Instance("ECLKSYNCB",
                i_ECLKI = sys2x_clk_ecsout,
                i_STOP  = self.stop,
                o_ECLKO = self.cd_sys2x.clk),
            Instance("CLKDIVF",
                p_DIV     = "2.0",
                i_ALIGNWD = 0,
                i_CLKI    = self.cd_sys2x.clk,
                i_RST     = self.reset,
                o_CDIVX   = self.cd_sys.clk),
            AsyncResetSynchronizer(self.cd_sys, ~pll.locked | self.reset),
        ]

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

class BaseSoC(SoCCore):
    def __init__(self, sys_clk_freq=80e6, toolchain="trellis", with_ethernet=False,
                 with_etherbone=False, with_led_chaser=True, **kwargs):
        platform = fpc_iii.Platform(toolchain=toolchain)

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

        # SoCCore ----------------------------------------------------------------------------------
        if kwargs[ "uart_name" ] == "serial":
            # Defaults to USB FIFO since no real serial.
            kwargs[ "uart_name" ] = "usb_fifo"
        SoCCore.__init__(self, platform, sys_clk_freq, ident = "LiteX SoC on FPC-III", **kwargs)

        # DDR3 SDRAM -------------------------------------------------------------------------------
        if not self.integrated_main_ram_size:
            ddram = platform.request("ddram")
            self.ddrphy = ECP5DDRPHY(ddram, sys_clk_freq, clk_polarity=1) # clk_p/n swapped.
            self.ddrphy.settings.rtt_nom = "disabled"
            self.comb += self.crg.stop.eq(self.ddrphy.init.stop)
            self.comb += self.crg.reset.eq(self.ddrphy.init.reset)
            self.comb += ddram.vccio.eq(Replicate(C(1), ddram.vccio.nbits))
            self.add_sdram("sdram",
                phy           = self.ddrphy,
                module        = IS43TR16256A(sys_clk_freq, "1:2"),
                l2_cache_size = kwargs.get("l2_size", 8192)
            )
        self.comb += platform.request("dram_vtt_en").eq(0 if self.integrated_main_ram_size else 1)

        # Ethernet ---------------------------------------------------------------------------------
        if with_ethernet or with_etherbone:
            self.ethphy = LiteEthPHYMII(
                clock_pads = self.platform.request("eth_clocks"),
                pads       = self.platform.request("eth"))
            if with_ethernet:
                self.add_ethernet(phy=self.ethphy)
            if with_etherbone:
                self.add_etherbone(phy=self.ethphy)

        # 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=fpc_iii.Platform, description="LiteX SoC on FPC-III.")
    parser.add_target_argument("--sys-clk-freq", default=80e6, type=float, help="System clock frequency.")
    ethopts = parser.target_group.add_mutually_exclusive_group()
    ethopts.add_argument("--with-ethernet",  action="store_true", help="Enable Ethernet support.")
    ethopts.add_argument("--with-etherbone", action="store_true", help="Enable Etherbone support.")
    sdopts = parser.target_group.add_mutually_exclusive_group()
    sdopts.add_argument("--with-spi-sdcard", action="store_true", help="Enable SPI-mode SDCard support.")
    sdopts.add_argument("--with-sdcard",     action="store_true", help="Enable SDCard support.")
    args = parser.parse_args()

    soc = BaseSoC(
        sys_clk_freq   = args.sys_clk_freq,
        toolchain      = args.toolchain,
        with_ethernet  = args.with_ethernet,
        with_etherbone = args.with_etherbone,
        **parser.soc_argdict)
    if args.with_spi_sdcard:
        soc.add_spi_sdcard()
    if args.with_sdcard:
        soc.add_sdcard()
    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(builder.get_bitstream_filename(mode="sram"))

if __name__ == "__main__":
    main()