litex/misoclib/mem/sdram/lasmicon/crossbar.py

from migen.fhdl.std import *
from migen.genlib import roundrobin
from migen.genlib.record import *
from migen.genlib.misc import optree

from misoclib.mem.sdram.bus.lasmibus import Interface

def _getattr_all(l, attr):
	it = iter(l)
	r = getattr(next(it), attr)
	for e in it:
		if getattr(e, attr) != r:
			raise ValueError
	return r

class Crossbar(Module):
	def __init__(self, controllers, cba_shift):
		self._controllers = controllers
		self._cba_shift = cba_shift

		self._rca_bits = _getattr_all(controllers, "aw")
		self._dw = _getattr_all(controllers, "dw")
		self._nbanks = _getattr_all(controllers, "nbanks")
		self._req_queue_size = _getattr_all(controllers, "req_queue_size")
		self._read_latency = _getattr_all(controllers, "read_latency")
		self._write_latency = _getattr_all(controllers, "write_latency")

		self._bank_bits = log2_int(self._nbanks, False)
		self._controller_bits = log2_int(len(self._controllers), False)

		self._masters = []

	def get_master(self):
		if self.finalized:
			raise FinalizeError
		lasmi_master = Interface(self._rca_bits + self._bank_bits + self._controller_bits,
			self._dw, 1, self._req_queue_size, self._read_latency, self._write_latency)
		self._masters.append(lasmi_master)
		return lasmi_master

	def do_finalize(self):
		nmasters = len(self._masters)

		m_ca, m_ba, m_rca = self._split_master_addresses(self._controller_bits,
			self._bank_bits, self._rca_bits, self._cba_shift)

		for nc, controller in enumerate(self._controllers):
			if self._controller_bits:
				controller_selected = [ca == nc for ca in m_ca]
			else:
				controller_selected = [1]*nmasters
			master_req_acks = [0]*nmasters
			master_dat_acks = [0]*nmasters
			rrs = [roundrobin.RoundRobin(nmasters, roundrobin.SP_CE) for n in range(self._nbanks)]
			self.submodules += rrs
			for nb, rr in enumerate(rrs):
				bank = getattr(controller, "bank"+str(nb))

				# for each master, determine if another bank locks it
				master_locked = []
				for nm, master in enumerate(self._masters):
					locked = 0
					for other_nb, other_rr in enumerate(rrs):
						if other_nb != nb:
							other_bank = getattr(controller, "bank"+str(other_nb))
							locked = locked | (other_bank.lock & (other_rr.grant == nm))
					master_locked.append(locked)

				# arbitrate
				bank_selected = [cs & (ba == nb) & ~locked for cs, ba, locked in zip(controller_selected, m_ba, master_locked)]
				bank_requested = [bs & master.stb for bs, master in zip(bank_selected, self._masters)]
				self.comb += [
					rr.request.eq(Cat(*bank_requested)),
					rr.ce.eq(~bank.stb & ~bank.lock)
				]

				# route requests
				self.comb += [
					bank.adr.eq(Array(m_rca)[rr.grant]),
					bank.we.eq(Array(self._masters)[rr.grant].we),
					bank.stb.eq(Array(bank_requested)[rr.grant])
				]
				master_req_acks = [master_req_ack | ((rr.grant == nm) & bank_selected[nm] & bank.req_ack)
					for nm, master_req_ack in enumerate(master_req_acks)]
				master_dat_acks = [master_dat_ack | ((rr.grant == nm) & bank.dat_ack)
					for nm, master_dat_ack in enumerate(master_dat_acks)]

			self.comb += [master.req_ack.eq(master_req_ack) for master, master_req_ack in zip(self._masters, master_req_acks)]
			self.comb += [master.dat_ack.eq(master_dat_ack) for master, master_dat_ack in zip(self._masters, master_dat_acks)]

			# route data writes
			controller_selected_wl = controller_selected
			for i in range(self._write_latency):
				n_controller_selected_wl = [Signal() for i in range(nmasters)]
				self.sync += [n.eq(o) for n, o in zip(n_controller_selected_wl, controller_selected_wl)]
				controller_selected_wl = n_controller_selected_wl
			dat_w_maskselect = []
			dat_we_maskselect = []
			for master, selected in zip(self._masters, controller_selected_wl):
				o_dat_w = Signal(self._dw)
				o_dat_we = Signal(self._dw//8)
				self.comb += If(selected,
						o_dat_w.eq(master.dat_w),
						o_dat_we.eq(master.dat_we)
					)
				dat_w_maskselect.append(o_dat_w)
				dat_we_maskselect.append(o_dat_we)
			self.comb += [
				controller.dat_w.eq(optree("|", dat_w_maskselect)),
				controller.dat_we.eq(optree("|", dat_we_maskselect))
			]

		# route data reads
		if self._controller_bits:
			for master in self._masters:
				controller_sel = Signal(self._controller_bits)
				for nc, controller in enumerate(self._controllers):
					for nb in range(nbanks):
						bank = getattr(controller, "bank"+str(nb))
						self.comb += If(bank.stb & bank.ack, controller_sel.eq(nc))
				for i in range(self._read_latency):
					n_controller_sel = Signal(self._controller_bits)
					self.sync += n_controller_sel.eq(controller_sel)
					controller_sel = n_controller_sel
				self.comb += master.dat_r.eq(Array(self._controllers)[controller_sel].dat_r)
		else:
			self.comb += [master.dat_r.eq(self._controllers[0].dat_r) for master in self._masters]

	def _split_master_addresses(self, controller_bits, bank_bits, rca_bits, cba_shift):
		m_ca = []	# controller address
		m_ba = []	# bank address
		m_rca = []	# row and column address
		for master in self._masters:
			cba = Signal(self._controller_bits + self._bank_bits)
			rca = Signal(self._rca_bits)
			cba_upper = cba_shift + controller_bits + bank_bits
			self.comb += cba.eq(master.adr[cba_shift:cba_upper])
			if cba_shift < self._rca_bits:
				if cba_shift:
					self.comb += rca.eq(Cat(master.adr[:cba_shift], master.adr[cba_upper:]))
				else:
					self.comb += rca.eq(master.adr[cba_upper:])
			else:
				self.comb += rca.eq(master.adr[:cba_shift])

			if self._controller_bits:
				ca = Signal(self._controller_bits)
				ba = Signal(self._bank_bits)
				self.comb += Cat(ba, ca).eq(cba)
			else:
				ca = None
				ba = cba

			m_ca.append(ca)
			m_ba.append(ba)
			m_rca.append(rca)
		return m_ca, m_ba, m_rca