litex/liteeth/core/arp/__init__.py

from liteeth.common import *
from liteeth.generic.depacketizer import LiteEthDepacketizer
from liteeth.generic.packetizer import LiteEthPacketizer

_arp_table_layout = [
		("reply", 1),
		("request", 1),
		("ip_address", 32),
		("mac_address", 48)
	]

class LiteEthARPDepacketizer(LiteEthDepacketizer):
	def __init__(self):
		LiteEthDepacketizer.__init__(self,
			eth_mac_description(8),
			eth_arp_description(8),
			arp_header,
			arp_header_len)

class LiteEthARPPacketizer(LiteEthPacketizer):
	def __init__(self):
		LiteEthPacketizer.__init__(self,
			eth_arp_description(8),
			eth_mac_description(8),
			arp_header,
			arp_header_len)

class LiteEthARPTX(Module):
	def __init__(self, mac_address, ip_address):
		self.sink = sink = Sink(_arp_table_layout)
		self.source = source = Source(eth_mac_description(8))
		###
		self.submodules.packetizer = packetizer = LiteEthARPPacketizer()

		counter = Counter(max=max(arp_header_len, eth_min_len))
		self.submodules += counter

		self.submodules.fsm = fsm = FSM(reset_state="IDLE")
		fsm.act("IDLE",
			sink.ack.eq(1),
			counter.reset.eq(1),
			If(sink.stb,
				sink.ack.eq(0),
				NextState("SEND")
			)
		)
		self.comb += [
			packetizer.sink.sop.eq(counter.value == 0),
			packetizer.sink.eop.eq(counter.value == max(arp_header_len, eth_min_len)-1),
			packetizer.sink.hwtype.eq(arp_hwtype_ethernet),
			packetizer.sink.proto.eq(arp_proto_ip),
			packetizer.sink.hwsize.eq(6),
			packetizer.sink.protosize.eq(4),
			packetizer.sink.sender_mac.eq(mac_address),
			packetizer.sink.sender_ip.eq(ip_address),
			If(sink.reply,
				packetizer.sink.opcode.eq(arp_opcode_reply),
				packetizer.sink.target_mac.eq(sink.mac_address),
				packetizer.sink.target_ip.eq(sink.ip_address)
			).Elif(sink.request,

				packetizer.sink.opcode.eq(arp_opcode_request),
				packetizer.sink.target_mac.eq(0xffffffffffff),
				packetizer.sink.target_ip.eq(sink.ip_address)
			)
		]
		fsm.act("SEND",
			packetizer.sink.stb.eq(1),
			Record.connect(packetizer.source, source),
			source.target_mac.eq(packetizer.sink.target_mac),
			source.sender_mac.eq(mac_address),
			source.ethernet_type.eq(ethernet_type_arp),
			If(source.stb & source.ack,
				counter.ce.eq(1),
				If(source.eop,
					sink.ack.eq(1),
					NextState("IDLE")
				)
			)
		)

class LiteEthARPRX(Module):
	def __init__(self, mac_address, ip_address):
		self.sink = sink = Sink(eth_mac_description(8))
		self.source = source = Source(_arp_table_layout)
		###
		self.submodules.depacketizer = depacketizer = LiteEthARPDepacketizer()
		self.comb += Record.connect(sink, depacketizer.sink)

		self.submodules.fsm = fsm = FSM(reset_state="IDLE")
		fsm.act("IDLE",
			depacketizer.source.ack.eq(1),
			If(depacketizer.source.stb & depacketizer.source.sop,
				depacketizer.source.ack.eq(0),
				NextState("CHECK")
			)
		)
		valid = Signal()
		self.sync += valid.eq(
			depacketizer.source.stb &
			(depacketizer.source.hwtype == arp_hwtype_ethernet) &
			(depacketizer.source.proto == arp_proto_ip) &
			(depacketizer.source.hwsize == 6) &
			(depacketizer.source.protosize == 4) &
			(depacketizer.source.target_ip == ip_address)
		)
		reply = Signal()
		request = Signal()
		self.comb += Case(depacketizer.source.opcode, {
			arp_opcode_request	:	[request.eq(1)],
			arp_opcode_reply	:	[reply.eq(1)],
			"default"			:	[]
			})
		self.comb += [
			source.ip_address.eq(depacketizer.source.sender_ip),
			source.mac_address.eq(depacketizer.source.sender_mac)
		]
		fsm.act("CHECK",
			If(valid,
				source.stb.eq(1),
				source.reply.eq(reply),
				source.request.eq(request)
			),
			NextState("TERMINATE")
		),
		fsm.act("TERMINATE",
			depacketizer.source.ack.eq(1),
			If(depacketizer.source.stb & depacketizer.source.eop,
				NextState("IDLE")
			)
		)

class LiteEthARPTable(Module):
	def __init__(self, clk_freq, max_requests=8):
		self.sink = sink = Sink(_arp_table_layout) 			# from arp_rx
		self.source = source = Source(_arp_table_layout) 	# to arp_tx

		# Request/Response interface
		self.request = request = Sink(arp_table_request_layout)
		self.response = response = Source(arp_table_response_layout)
		###
		request_timeout = Timeout(clk_freq//10)
		request_counter = Counter(max=max_requests)
		request_pending = FlipFlop()
		request_ip_address = FlipFlop(32)
		self.submodules += request_timeout, request_counter, request_pending, request_ip_address
		self.comb += [
			request_timeout.ce.eq(request_pending.q),
			request_pending.d.eq(1),
			request_ip_address.d.eq(request.ip_address)
		]

		# Note: Store only 1 IP/MAC couple, can be improved with a real
		# table in the future to improve performance when packets are
		# targeting multiple destinations.
		update = Signal()
		cached_valid = Signal()
		cached_ip_address = Signal(32)
		cached_mac_address = Signal(48)
		cached_timeout = Timeout(clk_freq*10)
		self.submodules += cached_timeout

		self.submodules.fsm = fsm = FSM(reset_state="IDLE")
		fsm.act("IDLE",
			# Note: for simplicicy, if APR table is busy response from arp_rx
			# is lost. This is compensated by the protocol (retries)
			If(sink.stb & sink.request,
				NextState("SEND_REPLY")
			).Elif(sink.stb & sink.reply & request_pending.q,
				NextState("UPDATE_TABLE"),
			).Elif(request_counter.value == max_requests-1,
				NextState("PRESENT_RESPONSE")
			).Elif(request.stb | (request_pending.q & request_timeout.reached),
				NextState("CHECK_TABLE")
			)
		)
		fsm.act("SEND_REPLY",
			source.stb.eq(1),
			source.reply.eq(1),
			source.ip_address.eq(sink.ip_address),
			If(source.ack,
				NextState("IDLE")
			)
		)
		fsm.act("UPDATE_TABLE",
			request_pending.reset.eq(1),
			update.eq(1),
			NextState("CHECK_TABLE")
		)
		self.sync += [
			If(update,
				cached_valid.eq(1),
				cached_ip_address.eq(sink.ip_address),
				cached_mac_address.eq(sink.mac_address),
				cached_timeout.reset.eq(1)
			).Else(
				cached_timeout.ce.eq(1),
				If(cached_timeout.reached,
					cached_valid.eq(0)
				)
			)
		]
		found = Signal()
		fsm.act("CHECK_TABLE",
			If(cached_valid,
				If(request_ip_address.q == cached_ip_address,
					request_ip_address.reset.eq(1),
					NextState("PRESENT_RESPONSE"),
				).Elif(request.ip_address == cached_ip_address,
					request.ack.eq(request.stb),
					NextState("PRESENT_RESPONSE"),
				).Else(
					request_ip_address.ce.eq(request.stb),
					NextState("SEND_REQUEST")
				)
			).Else(
				request_ip_address.ce.eq(request.stb),
				NextState("SEND_REQUEST")
			)
		)
		fsm.act("SEND_REQUEST",
			source.stb.eq(1),
			source.request.eq(1),
			source.ip_address.eq(request_ip_address.q),
			If(source.ack,
				request_timeout.reset.eq(1),
				request_counter.reset.eq(request.stb),
				request_counter.ce.eq(1),
				request_pending.ce.eq(1),
				request.ack.eq(1),
				NextState("IDLE")
			)
		)
		self.comb += [
			If(request_counter == max_requests-1,
				response.failed.eq(1),
				request_counter.reset.eq(1),
				request_pending.reset.eq(1)
			),
			response.mac_address.eq(cached_mac_address)
		]
		fsm.act("PRESENT_RESPONSE",
			response.stb.eq(1),
			If(response.ack,
				NextState("IDLE")
			)
		)

class LiteEthARP(Module):
	def __init__(self, mac, mac_address, ip_address, clk_freq):
		self.submodules.tx = tx = LiteEthARPTX(mac_address, ip_address)
		self.submodules.rx = rx = LiteEthARPRX(mac_address, ip_address)
		self.submodules.table = table = LiteEthARPTable(clk_freq)
		self.comb += [
			Record.connect(rx.source, table.sink),
			Record.connect(table.source, tx.sink)
		]
		mac_port = mac.crossbar.get_port(ethernet_type_arp)
		self.comb += [
			Record.connect(tx.source, mac_port.sink),
			Record.connect(mac_port.source, rx.sink)
		]