litex/milkymist/minimac3/__init__.py

from migen.fhdl.structure import *
from migen.fhdl.specials import Instance
from migen.bank.description import *
from migen.bank.eventmanager import *
from migen.bank import csrgen
from migen.bus import wishbone

_count_width = 11

class MiniMAC:
	def __init__(self, address):
		# PHY signals
		self.phy_tx_clk = Signal()
		self.phy_tx_data = Signal(4)
		self.phy_tx_en = Signal()
		self.phy_tx_er = Signal()
		self.phy_rx_clk = Signal()
		self.phy_rx_data = Signal(4)
		self.phy_dv = Signal()
		self.phy_rx_er = Signal()
		self.phy_col = Signal()
		self.phy_crs = Signal()
		self.phy_rst_n = Signal()
		
		# CPU interface
		self._phy_reset = RegisterField("phy_reset", reset=1)
		self._rx_count_0 = RegisterField("rx_count_0", _count_width, access_bus=READ_ONLY, access_dev=WRITE_ONLY)
		self._rx_count_1 = RegisterField("rx_count_1", _count_width, access_bus=READ_ONLY, access_dev=WRITE_ONLY)
		self._tx_count = RegisterField("tx_count", _count_width, access_dev=READ_WRITE)
		self._tx_start = RegisterRaw("tx_start")
		regs = [self._phy_reset, self._rx_count_0, self._rx_count_1, self._tx_count, self._tx_start]
		
		self._rx_event_0 = EventSourcePulse()
		self._rx_event_1 = EventSourcePulse()
		self._tx_event = EventSourcePulse()
		self.events = EventManager(self._rx_event_0, self._rx_event_1, self._tx_event)
		
		self.bank = csrgen.Bank(regs + self.events.get_registers(), address=address)
		self.membus = wishbone.Interface()
		
	def get_fragment(self):
		init = Signal(reset=1)
		rx_ready_0 = Signal()
		rx_ready_1 = Signal()
		rx_pending_0 = self._rx_event_0.pending
		rx_pending_1 = self._rx_event_1.pending
		rx_pending_0_r = Signal()
		rx_pending_1_r = Signal()
		comb = [
			self.phy_rst_n.eq(~self._phy_reset.field.r),
			
			rx_ready_0.eq(init | (rx_pending_0_r & ~rx_pending_0)),
			rx_ready_1.eq(init | (rx_pending_1_r & ~rx_pending_1)),
			
			self._tx_count.field.w.eq(0),
			self._tx_count.field.we.eq(self._tx_event.trigger)
		]
		sync = [
			init.eq(0),
			rx_pending_0_r.eq(rx_pending_0),
			rx_pending_1_r.eq(rx_pending_1)
		]
		inst = Instance("minimac3",
				Instance.ClockPort("sys_clk"),
				Instance.ResetPort("sys_rst"),

				Instance.Output("rx_done_0", self._rx_event_0.trigger),
				Instance.Output("rx_count_0", self._rx_count_0.field.w),
				Instance.Output("rx_done_1", self._rx_event_1.trigger),
				Instance.Output("rx_count_1", self._rx_count_1.field.w),
				Instance.Input("rx_ready_0", rx_ready_0),
				Instance.Input("rx_ready_1", rx_ready_1),

				Instance.Input("tx_start", self._tx_start.re),
				Instance.Input("tx_count", self._tx_count.field.r),
				Instance.Output("tx_done", self._tx_event.trigger),
				
				Instance.Input("wb_adr_i", self.membus.adr),
				Instance.Input("wb_dat_i", self.membus.dat_w),
				Instance.Input("wb_sel_i", self.membus.sel),
				Instance.Input("wb_stb_i", self.membus.stb),
				Instance.Input("wb_cyc_i", self.membus.cyc),
				Instance.Input("wb_we_i", self.membus.we),
				Instance.Output("wb_dat_o", self.membus.dat_r),
				Instance.Output("wb_ack_o", self.membus.ack),
				
				Instance.ClockPort("phy_tx_clk", "eth_tx"),
				Instance.Output("phy_tx_data", self.phy_tx_data),
				Instance.Output("phy_tx_en", self.phy_tx_en),
				Instance.Output("phy_tx_er", self.phy_tx_er),
				Instance.ClockPort("phy_rx_clk", "eth_rx"),
				Instance.Input("phy_rx_data", self.phy_rx_data),
				Instance.Input("phy_dv", self.phy_dv),
				Instance.Input("phy_rx_er", self.phy_rx_er),
				Instance.Input("phy_col", self.phy_col),
				Instance.Input("phy_crs", self.phy_crs))
		return Fragment(comb, sync, specials={inst}) \
			+ self.events.get_fragment() \
			+ self.bank.get_fragment()