uart2wb: copy UARTTX/UARTRX from MiSoC to avoid dependency

litescope/bridge/uart2wb.py

@@ -1,8 +1,105 @@
 from litescope.common import *
 from migen.bus import wishbone
 from migen.genlib.misc import chooser
+from migen.genlib.cdc import MultiReg
+from migen.bank.description import *
+from migen.bank.eventmanager import *
+from migen.genlib.record import Record
+from migen.flow.actor import Sink, Source
 
-from misoclib.uart import UARTRX, UARTTX
+class UARTRX(Module):
+	def __init__(self, pads, tuning_word):
+		self.source = Source([("d", 8)])
+
+		###
+
+		uart_clk_rxen = Signal()
+		phase_accumulator_rx = Signal(32)
+
+		rx = Signal()
+		self.specials += MultiReg(pads.rx, rx)
+		rx_r = Signal()
+		rx_reg = Signal(8)
+		rx_bitcount = Signal(4)
+		rx_busy = Signal()
+		rx_done = self.source.stb
+		rx_data = self.source.d
+		self.sync += [
+			rx_done.eq(0),
+			rx_r.eq(rx),
+			If(~rx_busy,
+				If(~rx & rx_r, # look for start bit
+					rx_busy.eq(1),
+					rx_bitcount.eq(0),
+				)
+			).Else(
+				If(uart_clk_rxen,
+					rx_bitcount.eq(rx_bitcount + 1),
+					If(rx_bitcount == 0,
+						If(rx, # verify start bit
+							rx_busy.eq(0)
+						)
+					).Elif(rx_bitcount == 9,
+						rx_busy.eq(0),
+						If(rx, # verify stop bit
+							rx_data.eq(rx_reg),
+							rx_done.eq(1)
+						)
+					).Else(
+						rx_reg.eq(Cat(rx_reg[1:], rx))
+					)
+				)
+			)
+		]
+		self.sync += \
+				If(rx_busy,
+					Cat(phase_accumulator_rx, uart_clk_rxen).eq(phase_accumulator_rx + tuning_word)
+				).Else(
+					Cat(phase_accumulator_rx, uart_clk_rxen).eq(2**31)
+				)
+
+class UARTTX(Module):
+	def __init__(self, pads, tuning_word):
+		self.sink = Sink([("d", 8)])
+
+		###
+
+		uart_clk_txen = Signal()
+		phase_accumulator_tx = Signal(32)
+
+		pads.tx.reset = 1
+
+		tx_reg = Signal(8)
+		tx_bitcount = Signal(4)
+		tx_busy = Signal()
+		self.sync += [
+			self.sink.ack.eq(0),
+			If(self.sink.stb & ~tx_busy & ~self.sink.ack,
+				tx_reg.eq(self.sink.d),
+				tx_bitcount.eq(0),
+				tx_busy.eq(1),
+				pads.tx.eq(0)
+			).Elif(uart_clk_txen & tx_busy,
+				tx_bitcount.eq(tx_bitcount + 1),
+				If(tx_bitcount == 8,
+					pads.tx.eq(1)
+				).Elif(tx_bitcount == 9,
+					pads.tx.eq(1),
+					tx_busy.eq(0),
+					self.sink.ack.eq(1),
+				).Else(
+					pads.tx.eq(tx_reg[0]),
+					tx_reg.eq(Cat(tx_reg[1:], 0))
+				)
+			)
+		]
+		self.sync += [
+				If(tx_busy,
+					Cat(phase_accumulator_tx, uart_clk_txen).eq(phase_accumulator_tx + tuning_word)
+				).Else(
+					Cat(phase_accumulator_tx, uart_clk_txen).eq(0)
+				)
+		]
 
 class UART(Module, AutoCSR):
 	def __init__(self, pads, clk_freq, baud=115200):