actorlib: LASMI DMA (untested)

migen/actorlib/dma_lasmi.py

@@ -0,0 +1,107 @@
+from migen.fhdl.std import *
+from migen.flow.actor import *
+from migen.genlib.fifo import SyncFIFO
+
+class Reader(Module):
+	def __init__(self, lasmim, fifo_depth=None):
+		self.address = Sink([("a", lasmim.aw)])
+		self.data = Source([("d", lasmim.dw)])
+		self.busy = Signal()
+	
+		###
+
+		if fifo_depth is None:
+			fifo_depth = lasmim.read_latency + 2
+		assert(fifo_depth >= lasmim.read_latency)
+	
+		# request issuance
+		request_enable = Signal()
+		request_issued = Signal()
+
+		self.comb += [
+			self.bus.we.eq(0),
+			lasmim.stb.eq(self.address.stb & request_enable),
+			lasmim.adr.eq(self.address.payload.a),
+			self.address.ack.eq(lasmim.ack),
+			request_issued.eq(lasmim.stb & lasmim.ack)
+		]
+
+		# FIFO reservation level counter
+		# incremented when data is planned to be queued
+		# decremented when data is dequeued
+		data_dequeued = Signal()
+		rsv_level = Signal(max=fifo_depth+1)
+		self.sync += [
+			If(request_issued,
+				If(~data_dequeued, rsv_level.eq(rsv_level + 1))
+			).Elif(data_dequeued,
+				rsv_level.eq(rsv_level - 1)
+			)
+		]
+		self.comb += [
+			self.busy.eq(rsv_level != 0),
+			request_enable.eq(rsv_level != fifo_depth)
+		]
+
+		# data available
+		data_available = request_issued
+		for i in range(lasmim.read_latency):
+			new_data_available = Signal()
+			self.sync += new_data_available.eq(data_available)
+			data_available = new_data_available
+
+		# FIFO
+		fifo = SyncFIFO(lasmim.dw, fifo_depth)
+		self.submodules += fifo
+
+		self.comb += [
+			fifo.din.eq(lasmim.dat_r),
+			fifo.we.eq(data_available),
+
+			self.data.stb.eq(fifo.readable),
+			fifo.re.eq(self.data.ack),
+			self.data.payload.d.eq(fifo.dout),
+			data_dequeued.eq(self.data.stb & self.data.ack)
+		]
+
+
+class Writer(Module):
+	def __init__(self, lasmim):
+		self.address_data = Sink([("a", lasmim.aw), ("d", lasmim.dw)])
+		self.busy = Signal()
+
+		###
+
+		self.comb += [
+			lasmim.we.eq(1),
+			lasmim.stb.eq(self.address_data.stb),
+			lasmim.adr.eq(self.address_data.payload.a),
+			self.address_data.ack.eq(lasmim.ack)
+		]
+
+		busy_expr = 0
+		data_valid = Signal()
+		data = Signal(lasmim.dw)
+		self.comb += [
+			data_valid.eq(lasmim.stb & lasmim.ack),
+			data.eq(self.address_data.payload.d)
+		]
+
+		for i in range(lasmim.write_latency):
+			new_data_valid = Signal()
+			new_data = Signal(lasmim.dw)
+			self.sync += [
+				new_data_valid.eq(data_valid),
+				new_data.eq(data)
+			]
+			busy_expr = busy_expr | new_data_valid
+			data_valid = new_data_valid
+			data = new_data
+
+		self.comb += [
+			If(data_valid,
+				lasmim.dat_we.eq(2**(lasmim.dw//8)-1),
+				lasmim.dat_w.eq(data)
+			),
+			self.busy.eq(busy_expr)
+		]