litex/migen/bank/eventmanager.py

from migen.fhdl.structure import *
from migen.fhdl.module import Module
from migen.bank.description import *
from migen.genlib.misc import optree

class _EventSource(HUID):
	def __init__(self):
		HUID.__init__(self)
		self.status = Signal() # value in the status register
		self.pending = Signal() # value in the pending register + assert irq if unmasked
		self.trigger = Signal() # trigger signal interface to the user design
		self.clear = Signal() # clearing attempt by W1C to pending register, ignored by some event sources

# set on a positive trigger pulse
class EventSourcePulse(Module, _EventSource):
	def __init__(self):
		_EventSource.__init__(self)
		self.comb += self.status.eq(0)
		self.sync += [
			If(self.clear, self.pending.eq(0)),
			If(self.trigger, self.pending.eq(1))
		]

# set on the falling edge of the trigger, status = trigger
class EventSourceProcess(Module, _EventSource):
	def __init__(self):
		_EventSource.__init__(self)
		self.comb += self.status.eq(self.trigger)
		old_trigger = Signal()
		self.sync += [
			If(self.clear, self.pending.eq(0)),
			old_trigger.eq(self.trigger),
			If(~self.trigger & old_trigger, self.pending.eq(1))
		]

# all status set by external trigger
class EventSourceLevel(Module, _EventSource):
	def __init__(self):
		_EventSource.__init__(self)
		self.comb += [
			self.status.eq(self.trigger),
			self.pending.eq(self.trigger)
		]

class EventManager(Module, AutoCSR):
	def __init__(self):
		self.irq = Signal()
	
	def do_finalize(self):
		sources_u = [v for v in self.__dict__.values() if isinstance(v, _EventSource)]
		sources = sorted(sources_u, key=lambda x: x.huid)
		n = len(sources)
		self.status = CSR(n)
		self.pending = CSR(n)
		self.enable = CSRStorage(n)

		for i, source in enumerate(sources):
			self.comb += [
				self.status.w[i].eq(source.status),
				If(self.pending.re & self.pending.r[i], source.clear.eq(1)),
				self.pending.w[i].eq(source.pending)
			]
		
		irqs = [self.pending.w[i] & self.enable.storage[i] for i in range(n)]
		self.comb += self.irq.eq(optree("|", irqs))

	def __setattr__(self, name, value):
		object.__setattr__(self, name, value)
		if isinstance(value, _EventSource):
			if self.finalized:
				raise FinalizeError
			self.submodules += value