serdes-transceiver/single_serdes_loopback.py

from migen import *
from sync_serdes import *
from migen.genlib.fifo import SyncFIFO
from migen.build.platforms.sinara import kasli
from migen.genlib.misc import WaitTimer
from kasli_crg import KasliCRG
from eem_helpers import generate_pads
from uart import UART
from io_loopback import SingleIOLoopback


SEPARATOR = Constant(0b0101)

class SingleSerDesLoopBack(Module):
    def __init__(self, io_pad, sys_clk_freq):
        self.uart_rx = Signal()
        self.uart_tx = Signal()

        self.submodules.uart = UART(round((115200/sys_clk_freq)*2**32))
        self.comb += [
            self.uart.phy_rx.eq(self.uart_rx),
            self.uart_tx.eq(self.uart.phy_tx),
        ]
        
        self.submodules.tx = SingleLineTX()
        self.submodules.rx = SingleLineRX()

        # Primary adjustment to master-slave bitslip
        self.submodules.bitslip_reader = BitSlipReader()
        self.submodules.slave_aligner = SlaveAligner()
        self.submodules.post_align_reader = BitSlipReader()

        # Optimal delay solver
        self.submodules.phase_reader = PhaseReader()
        self.submodules.delay_solver = DelayOptimizer()

        # self.submodules.delay_optimizer = DelayOptimizer()

        # The actual channel
        self.submodules.channel = SingleIOLoopback(io_pad)

        # Attach FIFO to UART TX, send rate is too slow w.r.t sysclk
        self.submodules.tx_fifo = SyncFIFO(8, 64)

        self.comb += [
            # Repetitively send 0b00100
            self.tx.txdata.eq(0b00100),

            # Loopback channel
            self.channel.i.eq(self.tx.ser_out),
            self.rx.ser_in_no_dly.eq(self.channel.o),
            self.channel.t.eq(self.tx.t_out),

            # TX path
            self.uart.tx_data.eq(self.tx_fifo.dout),
            self.uart.tx_stb.eq(self.tx_fifo.readable),
            self.tx_fifo.re.eq(self.uart.tx_ack),
        ]

        # Route deserializer to phase_reader & the delay tap optimizer
        self.comb += [
            # Start the reader initially
            self.bitslip_reader.start.eq(1),
            # Delay tap optimizer will start after the reader is done
            self.slave_aligner.start.eq(0),
            self.post_align_reader.start.eq(0),
            self.phase_reader.start.eq(0),
            self.delay_solver.start.eq(0),

            # RXDATA for both reader and optimzer
            self.bitslip_reader.loopback_rxdata.eq(self.rx.rxdata),
            self.slave_aligner.loopback_rxdata.eq(self.rx.rxdata),
            self.post_align_reader.loopback_rxdata.eq(self.rx.rxdata),
            self.phase_reader.loopback_rxdata.eq(self.rx.rxdata),
            self.delay_solver.loopback_rxdata.eq(self.rx.rxdata),

            # Delay tap value
            self.phase_reader.delay_tap.eq(self.rx.cnt_out),
            self.delay_solver.delay_tap.eq(self.rx.cnt_out),

            # Increment control enable, such that phase_reader can
            # increment tap value after delay measurement
            # Re-assign the incremnet control to the optimizer after the optimizer has started
            # If(self.delay_optimizer.start,
            #     self.rx.ce.eq(self.delay_optimizer.inc_en),
            # ).Else(
            #     self.rx.ce.eq(self.phase_reader.inc_en),
            # )
            self.rx.ce.eq(
                self.phase_reader.inc_en |
                self.delay_solver.inc_en
            ),
            self.rx.master_bitslip.eq(
                self.bitslip_reader.bitslip |
                self.slave_aligner.master_bitslip |
                self.post_align_reader.bitslip
            ),
            self.rx.slave_bitslip.eq(
                self.bitslip_reader.bitslip |
                self.slave_aligner.slave_bitslip |
                self.post_align_reader.bitslip
            ),
        ]

        # Show measured result on UART
        delay_tap_count = Signal(6)
        bitslip_count = Signal(3)
        post_align_bitslip_count = Signal(3)

        fsm = FSM(reset_state="WAIT_DONE")
        self.submodules += fsm

        fsm.act("WAIT_DONE",
            If(self.bitslip_reader.done,
                NextState("WRITE_UPPER"),
            ),
        )

        fsm.act("WRITE_UPPER",
            # Exist state if all results are sent
            If(bitslip_count == 5,
                NextState("START_SLAVE_ALIGNER"),
            ).Elif(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(self.bitslip_reader.data_result[bitslip_count][8:]),
                NextState("WRITE_LOWER"),
            ),
        )

        fsm.act("WRITE_LOWER",
            self.tx_fifo.we.eq(1),
            self.tx_fifo.din.eq(self.bitslip_reader.data_result[bitslip_count][:8]),
            NextValue(bitslip_count, bitslip_count + 1),
            NextState("WRITE_UPPER"),
        )

        fsm.act("START_SLAVE_ALIGNER",
            self.slave_aligner.start.eq(1),
            # self.rx.ce.eq(self.delay_optimizer.inc_en),
            If(self.slave_aligner.done,
                NextState("WRITE_DONE_UPPER"),
            ).Else(
                NextState("START_SLAVE_ALIGNER")
            )
        )

        fsm.act("WRITE_DONE_UPPER",
            self.post_align_reader.start.eq(1),
            If(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(0xFF),
                NextState("WRITE_DONE_LOWER")
            )
        )

        fsm.act("WRITE_DONE_LOWER",
            self.post_align_reader.start.eq(1),
            If(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(0xFF),
                NextState("REREAD_BITSLIP")
            )
        )

        fsm.act("REREAD_BITSLIP",
            If(self.post_align_reader.done,
                NextState("REWRITE_UPPER"),
            ).Else(
                NextState("REREAD_BITSLIP"),
            ),
        )

        fsm.act("REWRITE_UPPER",
            # Exist state if all results are sent
            If(post_align_bitslip_count == 5,
                NextState("WRITE_B2P_DIVIDER_UPPER"),
            ).Elif(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(self.post_align_reader.data_result[post_align_bitslip_count][8:]),
                NextState("REWRITE_LOWER"),
            ),
        )

        fsm.act("REWRITE_LOWER",
            self.tx_fifo.we.eq(1),
            self.tx_fifo.din.eq(self.post_align_reader.data_result[post_align_bitslip_count][:8]),
            NextValue(post_align_bitslip_count, post_align_bitslip_count + 1),
            NextState("REWRITE_UPPER"),
        )

        fsm.act("WRITE_B2P_DIVIDER_UPPER",
            self.phase_reader.start.eq(1),
            If(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(0xFF),
                NextState("WRITE_B2P_DIVIDER_LOWER"),
            )
        )

        fsm.act("WRITE_B2P_DIVIDER_LOWER",
            self.phase_reader.start.eq(1),
            If(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(0xFF),
                NextState("WAIT_PHASE_READER"),
            )
        )

        fsm.act("WAIT_PHASE_READER",
            If(self.phase_reader.done,
                NextState("WRITE_DELAY_UPPER"),
            ).Else(
                NextState("WAIT_PHASE_READER"),
            )
        )

        fsm.act("WRITE_DELAY_UPPER",
            If(delay_tap_count == 32,
                NextState("DELAY_SOLVER_DIVIDER_UPPER")
            ).Elif(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(self.phase_reader.data_result[delay_tap_count][8:]),
                NextState("WRITE_DELAY_LOWER"),
            ),
        )

        fsm.act("WRITE_DELAY_LOWER",
            If(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(self.phase_reader.data_result[delay_tap_count][:8]),
                NextValue(delay_tap_count, delay_tap_count + 1),
                NextState("WRITE_DELAY_UPPER")
            ),
        )

        fsm.act("DELAY_SOLVER_DIVIDER_UPPER",
            self.delay_solver.start.eq(1),
            If(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(0xFF),
                NextState("DELAY_SOLVER_DIVIDER_LOWER"),
            )
        )

        fsm.act("DELAY_SOLVER_DIVIDER_LOWER",
            self.delay_solver.start.eq(1),
            If(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(0xFF),
                NextState("WAIT_DELAY_SOLVER"),
            )
        )

        fsm.act("WAIT_DELAY_SOLVER",
            If(self.delay_solver.done,
                NextState("WRITE_UPPER_ZERO"),
            ).Else(
                NextState("WAIT_DELAY_SOLVER"),
            )
        )

        fsm.act("WRITE_UPPER_ZERO",
            If(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(0x00),
                NextState("WRITE_LOWER_OPT"),
            )
        )

        fsm.act("WRITE_LOWER_OPT",
            If(self.tx_fifo.writable,
                self.tx_fifo.we.eq(1),
                self.tx_fifo.din.eq(self.delay_solver.opt_delay_tap),
                NextState("TERMINATE"),
            ),
        )

        fsm.act("TERMINATE",
            NextState("TERMINATE"),
        )

        # # Output control
        # self.sync += [
        #     # Send data to FIFO if not repeated
        #     If(self.rxdata_r[:5] != self.rx.rxdata,
        #         self.rxdata_r.eq(self.rx.rxdata),
        #         self.tx_fifo.din.eq(self.rx.rxdata),
        #         self.tx_fifo.we.eq(1)
        #     ).Else(
        #         self.tx_fifo.we.eq(0)
        #     )
        # ]


if __name__ == "__main__":
    platform = kasli.Platform(hw_rev="v2.0")

    # Generate pads for the I/O blocks
    eem = 3
    generate_pads(platform, eem)
    # pads = [
    #     platform.request("dio{}".format(eem), i) for i in range(4)
    # ]
    pad = platform.request("dio{}".format(eem), 0)

    crg = KasliCRG(platform)
    top = SingleSerDesLoopBack(pad, crg.sys_clk_freq)

    # Wire up UART core to the pads
    uart_pads = platform.request("serial")
    top.comb += [
        top.uart_rx.eq(uart_pads.rx),
        uart_pads.tx.eq(top.uart_tx),
    ]

    top.submodules += crg
    platform.build(top)