From 89dbf17cb62f34816be2b812972fe64bc790fa95 Mon Sep 17 00:00:00 2001 From: Florent Kermarrec Date: Fri, 1 Oct 2021 19:56:10 +0200 Subject: [PATCH] mac/sram: Cleanup/Simplify LiteEthMACSRAMWriter. - Improve signal names. - Avoid IDLE State. - Also check for error when length > eth_mtu. - Use int(math.log2()) instead of log2_int. --- liteeth/mac/sram.py | 159 +++++++++++++++++++++----------------------- 1 file changed, 74 insertions(+), 85 deletions(-) diff --git a/liteeth/mac/sram.py b/liteeth/mac/sram.py index 3456269..2636af6 100644 --- a/liteeth/mac/sram.py +++ b/liteeth/mac/sram.py @@ -7,7 +7,7 @@ # Copyright (c) 2017 whitequark # SPDX-License-Identifier: BSD-2-Clause -from math import log2, ceil +import math from liteeth.common import * @@ -18,122 +18,111 @@ from litex.soc.interconnect.csr_eventmanager import * class LiteEthMACSRAMWriter(Module, AutoCSR): def __init__(self, dw, depth, nslots=2, endianness="big", timestamp=None): - assert dw in [32, 64] + # Endpoint / Signals. self.sink = sink = stream.Endpoint(eth_phy_description(dw)) self.crc_error = Signal() - slotbits = max(log2_int(nslots), 1) - lengthbits = 32 + # Parameters Check / Compute. + assert dw in [32, 64] + slotbits = max(int(math.log2(nslots)), 1) + lengthbits = bits_for(depth * dw//8) + # CSRs. self._slot = CSRStatus(slotbits) self._length = CSRStatus(lengthbits) - self._errors = CSRStatus(32) + self._errors = CSRStatus(32) + # Optional Timestamp of the incoming packets and expose value to software. if timestamp is not None: - # Timestamp the incoming packets when a Timestamp source is provided - # and expose value to a software. timestampbits = len(timestamp) self._timestamp = CSRStatus(timestampbits) + # Event Manager. self.submodules.ev = EventManager() self.ev.available = EventSourceLevel() self.ev.finalize() # # # - # Packet dropped if no slot available + write = Signal() + errors = self._errors.status + + slot = Signal(slotbits) + length = Signal(lengthbits) + length_inc = Signal(4) + + # Sink is already ready: packets are dropped when no slot is available. sink.ready.reset = 1 # Decode Length increment from from last_be. - inc = Signal(4) if dw == 32: self.comb += Case(sink.last_be, { - 0b0001 : inc.eq(1), - 0b0010 : inc.eq(2), - 0b0100 : inc.eq(3), - "default" : inc.eq(4) + 0b0001 : length_inc.eq(1), + 0b0010 : length_inc.eq(2), + 0b0100 : length_inc.eq(3), + "default" : length_inc.eq(4) }) else: self.comb += Case(sink.last_be, { - 0b00000001 : inc.eq(1), - 0b00000010 : inc.eq(2), - 0b00000100 : inc.eq(3), - 0b00001000 : inc.eq(4), - 0b00010000 : inc.eq(5), - 0b00100000 : inc.eq(6), - 0b01000000 : inc.eq(7), - "default" : inc.eq(8) + 0b00000001 : length_inc.eq(1), + 0b00000010 : length_inc.eq(2), + 0b00000100 : length_inc.eq(3), + 0b00001000 : length_inc.eq(4), + 0b00010000 : length_inc.eq(5), + 0b00100000 : length_inc.eq(6), + 0b01000000 : length_inc.eq(7), + "default" : length_inc.eq(8) }) - counter = Signal(lengthbits) - - # Slot computation - slot = Signal(slotbits) - slot_ce = Signal() - self.sync += If(slot_ce, slot.eq(slot + 1)) - - start = Signal() - ongoing = Signal() - - # Status FIFO + # Status FIFO. stat_fifo_layout = [("slot", slotbits), ("length", lengthbits)] if timestamp is not None: stat_fifo_layout += [("timestamp", timestampbits)] + self.submodules.stat_fifo = stat_fifo = stream.SyncFIFO(stat_fifo_layout, nslots) - stat_fifo = stream.SyncFIFO(stat_fifo_layout, nslots) - self.submodules += stat_fifo - - # FSM - self.submodules.fsm = fsm = FSM(reset_state="IDLE") - fsm.act("IDLE", + # FSM. + self.submodules.fsm = fsm = FSM(reset_state="WRITE") + fsm.act("WRITE", If(sink.valid, If(stat_fifo.sink.ready, - start.eq(1), - ongoing.eq(1), - NextValue(counter, counter + inc), - NextState("WRITE") + write.eq(1), + NextValue(length, length + length_inc), + If(length >= eth_mtu, + NextState("DISCARD-REMAINING") + ), + If(sink.last, + If((sink.error & sink.last_be) != 0, + NextState("DISCARD") + ).Else( + NextState("TERMINATE") + ) + ) ).Else( - NextValue(self._errors.status, self._errors.status + 1), - NextState("DISCARD_REMAINING") + NextValue(errors, errors + 1), + NextState("DISCARD-REMAINING") ) ) ) - fsm.act("WRITE", - If(sink.valid, - If(counter == eth_mtu, - NextState("DISCARD_REMAINING") + fsm.act("DISCARD-REMAINING", + If(sink.valid & sink.last, + If((sink.error & sink.last_be) != 0, + NextState("DISCARD") ).Else( - NextValue(counter, counter + inc), - ongoing.eq(1) - ), - If(sink.last, - If((sink.error & sink.last_be) != 0, - NextState("DISCARD") - ).Else( - NextState("TERMINATE") - ) + NextState("TERMINATE") ) ) ) fsm.act("DISCARD", - NextValue(counter, 0), - NextState("IDLE") + NextValue(length, 0), + NextState("WRITE") ) - fsm.act("DISCARD_REMAINING", - If(sink.valid & sink.last, - NextState("TERMINATE") - ) - ) - self.comb += [ - stat_fifo.sink.slot.eq(slot), - stat_fifo.sink.length.eq(counter) - ] - fsm.act("TERMINATE", - NextValue(counter, 0), - slot_ce.eq(1), stat_fifo.sink.valid.eq(1), - NextState("IDLE") + stat_fifo.sink.slot.eq(slot), + stat_fifo.sink.length.eq(length), + NextValue(length, 0), + NextValue(slot, slot + 1), + NextState("WRITE") ) self.comb += [ @@ -143,11 +132,11 @@ class LiteEthMACSRAMWriter(Module, AutoCSR): self._length.status.eq(stat_fifo.source.length), ] if timestamp is not None: - # Latch Timestamp on start of incoming packet. - self.sync += If(start, stat_fifo.sink.timestamp.eq(timestamp)) + # Latch Timestamp on start of packet. + self.sync += If(sink.length == 0, stat_fifo.sink.timestamp.eq(timestamp)) self.comb += self._timestamp.status.eq(stat_fifo.source.timestamp) - # Memory + # Memory. mems = [None] * nslots ports = [None] * nslots for n in range(nslots): @@ -160,9 +149,9 @@ class LiteEthMACSRAMWriter(Module, AutoCSR): cases = {} for n, port in enumerate(ports): cases[n] = [ - ports[n].adr.eq(counter[log2_int(dw // 8):]), + ports[n].adr.eq(length[int(math.log2(dw//8)):]), ports[n].dat_w.eq(data), - If(sink.valid & ongoing, + If(sink.valid & write, ports[n].we.eq(0xf) ) ] @@ -175,13 +164,13 @@ class LiteEthMACSRAMReader(Module, AutoCSR): assert dw in [32, 64] self.source = source = stream.Endpoint(eth_phy_description(dw)) - slotbits = max(log2_int(nslots), 1) - lengthbits = bits_for(depth * (dw // 8)) # length in bytes + slotbits = max(int(math.log2(nslots)), 1) + lengthbits = bits_for(depth * dw//8) self.lengthbits = lengthbits self._start = CSR() self._ready = CSRStatus() - self._level = CSRStatus(log2_int(nslots) + 1) + self._level = CSRStatus(int(math.log2(nslots)) + 1) self._slot = CSRStorage(slotbits, reset_less=True) self._length = CSRStorage(lengthbits, reset_less=True) @@ -235,7 +224,7 @@ class LiteEthMACSRAMReader(Module, AutoCSR): ) # Encode Length to last_be. - length_lsb = cmd_fifo.source.length[0:log2_int(dw // 8)] + length_lsb = cmd_fifo.source.length[0:int(math.log2(dw//8))] if dw == 32: self.comb += If(source.last, Case(length_lsb, { @@ -261,11 +250,11 @@ class LiteEthMACSRAMReader(Module, AutoCSR): fsm.act("SEND", source.valid.eq(1), - source.last.eq(counter >= (cmd_fifo.source.length - (dw // 8))), + source.last.eq(counter >= (cmd_fifo.source.length - dw//8)), read_address.eq(counter), If(source.ready, - read_address.eq(counter + (dw // 8)), - NextValue(counter, counter + (dw // 8)), + read_address.eq(counter + dw//8), + NextValue(counter, counter + dw//8), If(source.last, NextState("END") ) @@ -298,7 +287,7 @@ class LiteEthMACSRAMReader(Module, AutoCSR): cases = {} for n, port in enumerate(ports): - self.comb += ports[n].adr.eq(read_address[log2_int(dw // 8):]) + self.comb += ports[n].adr.eq(read_address[int(math.log2(dw//8)):]) cases[n] = [data.eq(port.dat_r)] self.comb += [