serdes-transceiver/kasli_crg.py

from migen import *
from migen.build.platforms.sinara import kasli
from migen.genlib.resetsync import AsyncResetSynchronizer


class KasliCRG(Module):
    def __init__(self, platform):
        self.platform = platform

        # Generated clock domains
        self.clock_domains.cd_sys = ClockDomain()
        self.clock_domains.cd_sys5x = ClockDomain()
        self.clock_domains.cd_rx_sys = ClockDomain()
        self.clock_domains.cd_rx_sys5x = ClockDomain()
        self.clock_domains.cd_clk200 = ClockDomain()

        # Configure system clock using GTP ports
        self.sys_clk_freq = 125e6
        clk125 = self.platform.request("clk125_gtp")
        clk125_buf = Signal()
        clk125_div2 = Signal()

        self.specials += Instance("IBUFDS_GTE2",
            i_CEB=0,
            i_I=clk125.p, i_IB=clk125.n,
            o_O=clk125_buf,
            o_ODIV2=clk125_div2)

        # MMCM to generate different frequencies
        mmcm_fb = Signal()
        mmcm_locked = Signal()
        mmcm_sys = Signal()
        mmcm_sys5x = Signal()
        mmcm_rx_sys = Signal()
        mmcm_rx_sys5x = Signal()

        # PLL to IDELAYCTRL clock
        pll_locked = Signal()
        pll_fb = Signal()
        pll_clk200 = Signal()

        # Actual MMCM/PLL instances
        self.specials += [
            Instance("MMCME2_BASE",
                p_CLKIN1_PERIOD=16.0,
                i_CLKIN1=clk125_div2,

                i_CLKFBIN=mmcm_fb,
                o_CLKFBOUT=mmcm_fb,
                o_LOCKED=mmcm_locked,

                # VCO @ 1.25GHz with MULT=20
                p_CLKFBOUT_MULT_F=20.0, p_DIVCLK_DIVIDE=1,

                # ~125MHz
                p_CLKOUT0_DIVIDE_F=10.0, p_CLKOUT0_PHASE=0.0, o_CLKOUT0=mmcm_sys,

                # ~625MHz
                p_CLKOUT1_DIVIDE=2, p_CLKOUT1_PHASE=0.0, o_CLKOUT1=mmcm_sys5x,

                # ~125MHz separated from sysclk, for RX
                p_CLKOUT2_DIVIDE=10, p_CLKOUT2_PHASE=0.0, o_CLKOUT2=mmcm_rx_sys,

                # ~625MHz separated from sysclk, for RX
                p_CLKOUT3_DIVIDE=2, p_CLKOUT3_PHASE=0.0, o_CLKOUT3=mmcm_rx_sys5x,

                # Leftovers...
                # p_CLKOUT2_DIVIDE=2, p_CLKOUT2_PHASE=90.0, o_CLKOUT2=mmcm_sys4x_dqs,
            ),
            Instance("PLLE2_BASE",
                p_CLKIN1_PERIOD=16.0,
                i_CLKIN1=clk125_div2,

                i_CLKFBIN=pll_fb,
                o_CLKFBOUT=pll_fb,
                o_LOCKED=pll_locked,

                # VCO @ 1GHz
                p_CLKFBOUT_MULT=16, p_DIVCLK_DIVIDE=1,

                # 200MHz for IDELAYCTRL
                p_CLKOUT0_DIVIDE=5, p_CLKOUT0_PHASE=0.0, o_CLKOUT0=pll_clk200,
            ),
        ]

        self.specials += [
            Instance("BUFG", i_I=mmcm_sys, o_O=self.cd_sys.clk),
            Instance("BUFG", i_I=mmcm_sys5x, o_O=self.cd_sys5x.clk),
            Instance("BUFG", i_I=mmcm_rx_sys, o_O=self.cd_rx_sys.clk),
            Instance("BUFG", i_I=mmcm_rx_sys5x, o_O=self.cd_rx_sys5x.clk),
            Instance("BUFG", i_I=pll_clk200, o_O=self.cd_clk200.clk),
            AsyncResetSynchronizer(self.cd_clk200, ~pll_locked),
        ]

        reset_counter = Signal(4, reset=15)
        ic_reset = Signal(reset=1)
        self.sync.clk200 += \
            If(reset_counter != 0,
                reset_counter.eq(reset_counter - 1)
            ).Else(
                ic_reset.eq(0)
            )
        self.specials += Instance("IDELAYCTRL", i_REFCLK=ClockSignal("clk200"), i_RST=ic_reset)

        # Add clock costraints for all clock signals
        platform.add_period_constraint(self.cd_sys.clk, 8.)
        platform.add_period_constraint(self.cd_sys5x.clk, 1.6)
        platform.add_period_constraint(self.cd_rx_sys.clk, 8.)
        platform.add_period_constraint(self.cd_rx_sys5x.clk, 1.6)
        platform.add_period_constraint(self.cd_clk200.clk, 5.)

        platform.add_platform_command(
            "set_false_path -quiet "
            "-through [get_pins -filter {{REF_PIN_NAME == OQ || REF_PIN_NAME == TQ}} "
                "-of [get_cells -filter {{REF_NAME == OSERDESE2}}]] "
            "-to [get_pins -filter {{REF_PIN_NAME == D}} "
                "-of [get_cells -filter {{REF_NAME == ISERDESE2}}]]"
        )
        platform.add_platform_command(
            "set_false_path -quiet "
            "-through [get_pins -filter {{REF_PIN_NAME == OQ || REF_PIN_NAME == TQ}} "
                "-of [get_cells -filter {{REF_NAME == OSERDESE2}}]] "
            "-to [get_pins -filter {{REF_PIN_NAME == DDLY}} "
                "-of [get_cells -filter {{REF_NAME == ISERDESE2}}]]"
        )