artiq-zynq/src/gateware/aux_controller.py

"""Auxiliary controller, common to satellite and master"""

from migen import *
from migen.fhdl.simplify import FullMemoryWE

from misoc.interconnect.csr import *
from migen_axi.interconnect import axi
from artiq.gateware.drtio.aux_controller import Transmitter, Receiver

max_packet = 1024

OUT_BURST_LEN = 10
IN_BURST_LEN = 4

class SRAM(Module):
    def __init__(self, mem_or_size, read_only=False, init=None, bus=None):

        # SRAM initialisation

        if bus is None:
            bus = axi.Interface()
        self.bus = bus
        bus_data_width = len(self.bus.r.data)
        bus_addr_width = len(self.bus.ar.addr)
        if isinstance(mem_or_size, Memory):
            assert(mem_or_size.width <= bus_data_width)
            self.mem = mem_or_size
        else:
            self.mem = Memory(bus_data_width, mem_or_size//(bus_data_width//8), init=init)

        # memory
        port = self.mem.get_port(write_capable=not read_only, we_granularity=8)
        self.specials += self.mem, port

        ###

        # probably will get removed
        self.addr_base = CSRStorage(32)
        self.trig_count = CSRStatus(32)
        self.write_count = CSRStatus(32)

        self.trigger_stb = Signal()

        # Dout : Data received from CPU, output by SRAM <- port.dat_r
        # Din : Data driven into SRAM, written into CPU <- port.dat_w
        # When stb assert, index shows word being read/written, dout/din holds <- will be removed
        # data
        #
        # Cycle:
        # trigger_stb pulsed at start
        # Then out_burst_len words are strobed out of dout
        # Then, when din_ready is high, in_burst_len words are strobed in to din
        self.dout_stb = Signal() # there's no strobe signal for SRAM
        self.din_stb = Signal()
        self.dout_index = Signal(bus_addr_width)  # is this legal?
        self.din_index = Signal(bus_addr_width)
        self.din_ready = Signal()
        self.dout = Signal(64)
        self.din = Signal(64)

        # probably not correct here
        self.sync += If(self.trigger_stb, self.trig_count.status.eq(self.trig_count.status+1))

        ar, aw, w, r, b = attrgetter("ar", "aw", "w", "r", "b")(bus)

        ### Read
        self.comb += [
            ar.addr.eq(port.adr),  # shouldn't it be the other way around?
            port.dat_r.eq(r.data),
            r.ready.eq(1),
            ar.burst.eq(axi.Burst.incr.value),
            ar.len.eq(OUT_BURST_LEN-1), # Number of transfers in burst (0->1 transfer, 1->2 transfers...)
            ar.size.eq(3), # Width of burst: 3 = 8 bytes = 64 bits
            ar.cache.eq(0xf),
        ]

        # read control
        self.submodules.read_fsm = read_fsm = FSM(reset_state="IDLE")
        read_fsm.act("IDLE",
            If(self.trigger_stb,
                ar.valid.eq(1),
                If(ar.ready,
                    NextState("READ")
                ).Else(
                    NextState("READ_START")
                )
            )
        )
        read_fsm.act("READ_START",
            ar.valid.eq(1),
            If(ar.ready,
                NextState("READ"),
            )
        )
        read_fsm.act("READ",
            ar.valid.eq(0),
            If(r.last & r.valid,
                NextState("IDLE")
            )
        )

        self.sync += [
            If(read_fsm.ongoing("IDLE"),
                self.dout_index.eq(0) 
            ).Else(If(r.valid & read_fsm.ongoing("READ"),
                    self.dout_index.eq(self.dout_index+1),
                    port.adr.eq(port.adr + self.dout_index) # update address in the port
                )
            )
        ]

        # possibly unnecessary too
        self.comb += self.dout_stb.eq(r.valid & r.ready)

        ### Write
        self.comb += [
            w.data.eq(port.dat_w),
            aw.addr.eq(port.addr), # shouldn't it be the other way around?
            w.strb.eq(0xff),
            aw.burst.eq(axi.Burst.incr.value),
            aw.len.eq(IN_BURST_LEN-1), # Number of transfers in burst minus 1
            aw.size.eq(3), # Width of burst: 3 = 8 bytes = 64 bits
            aw.cache.eq(0xf),
            b.ready.eq(1),
        ]

        self.submodules.write_fsm = write_fsm = FSM(reset_state="IDLE")
        write_fsm.act("IDLE",
            w.valid.eq(0),
            aw.valid.eq(0),
            If(self.trigger_stb,
                aw.valid.eq(1),
                If(aw.ready, # assumes aw.ready is not randomly deasserted
                    NextState("DATA_WAIT")
                ).Else(
                    NextState("AW_READY_WAIT")
                )
            )
        )
        write_fsm.act("AW_READY_WAIT",
            aw.valid.eq(1),
            If(aw.ready,
                NextState("DATA_WAIT"),
            )
        )
        write_fsm.act("DATA_WAIT",
            aw.valid.eq(0),
            If(self.din_ready,  # probably unnecessary?
                w.valid.eq(1),
                NextState("WRITE")
            )
        )
        write_fsm.act("WRITE",
            w.valid.eq(1),
            If(w.ready & w.last,
                NextState("IDLE")
            )
        )

        # refer to port.we instead
        self.sync += If(w.ready & w.valid, port.we.eq(1))

        self.sync += [
            If(write_fsm.ongoing("IDLE"),
                self.din_index.eq(0) # replace with address?
            ), # but need to synchronise the address too
            If(w.ready & w.valid, self.din_index.eq(self.din_index+1), port.adr.eq(port.addr+self.din_index))
        ]

        self.comb += [
            w.last.eq(0),
            If(self.din_index==aw.len, w.last.eq(1))
        ]

        # check if necessary
        self.comb += self.din_stb.eq(w.valid & w.ready)


        # # generate write enable signal
        # if not read_only:
        #     #                          replace with?      stb -> w.strb    we->w.ready?     sel[i]-> r.valid
        #     self.comb += [port.we[i].eq(self.bus.cyc & self.bus.w.strb & self.bus.w.ready & self.bus.r.valid)
        #         for i in range(4)]
        # # address and data
        # self.comb += [
        #     self.bus.r.ready.eq(self.bus.r.valid), # AXI handshake?
        #     port.adr.eq(self.bus.ar.addr[:len(port.adr)]),
        #     self.bus.r.data.eq(port.dat_r)
        # ]
        # if not read_only:
        #     self.comb += port.dat_w.eq(self.bus.w.data),
        # # generate ack
        # self.sync += [
        #     self.bus.ack.eq(0),
        #     If(self.bus.cyc & self.bus.stb & ~self.bus.ack, self.bus.ack.eq(1))
        # ]

# TODO: FullMemoryWE should be applied by migen.build
@FullMemoryWE()
class DRTIOAuxController(Module):
    def __init__(self, link_layer):
        self.bus = axi.Interface()
        self.submodules.transmitter = Transmitter(link_layer, len(self.bus.w.data))
        self.submodules.receiver = Receiver(link_layer, len(self.bus.w.data))

        # probably will need to make axi.SRAM based on wb code
        tx_sdram_if = SRAM(self.transmitter.mem, read_only=False)
        rx_sdram_if = SRAM(self.receiver.mem, read_only=True)
        wsb = log2_int(len(self.w.data)//8)
        decoder = axi.AddressDecoder(self.bus,
            [(lambda a: a[log2_int(max_packet)-wsb] == 0, tx_sdram_if.bus),
             (lambda a: a[log2_int(max_packet)-wsb] == 1, rx_sdram_if.bus)],
            register=True)
        self.submodules += tx_sdram_if, rx_sdram_if, decoder

    def get_csrs(self):
        return self.transmitter.get_csrs() + self.receiver.get_csrs()