litex/migen/bus/lasmibus.py

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from migen.fhdl.std import *
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from migen.bus.transactions import *
from migen.genlib import roundrobin
from migen.genlib.record import *
from migen.genlib.misc import optree
class Interface(Record):
def __init__(self, aw, dw, nbanks, req_queue_size, read_latency, write_latency):
self.aw = aw
self.dw = dw
self.nbanks = nbanks
self.req_queue_size = req_queue_size
self.read_latency = read_latency
self.write_latency = write_latency
bank_layout = [
("adr", aw, DIR_M_TO_S),
("we", 1, DIR_M_TO_S),
("stb", 1, DIR_M_TO_S),
("req_ack", 1, DIR_S_TO_M),
("dat_ack", 1, DIR_S_TO_M),
("lock", 1, DIR_S_TO_M)
]
if nbanks > 1:
layout = [("bank"+str(i), bank_layout) for i in range(nbanks)]
else:
layout = bank_layout
layout += [
("dat_w", dw, DIR_M_TO_S),
("dat_we", dw//8, DIR_M_TO_S),
("dat_r", dw, DIR_S_TO_M)
]
Record.__init__(self, layout)
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, nmasters, cba_shift):
ncontrollers = len(controllers)
rca_bits = _getattr_all(controllers, "aw")
dw = _getattr_all(controllers, "dw")
nbanks = _getattr_all(controllers, "nbanks")
req_queue_size = _getattr_all(controllers, "req_queue_size")
read_latency = _getattr_all(controllers, "read_latency")
write_latency = _getattr_all(controllers, "write_latency")
bank_bits = log2_int(nbanks, False)
controller_bits = log2_int(ncontrollers, False)
self.masters = [Interface(rca_bits + bank_bits + controller_bits, dw, 1, req_queue_size, read_latency, write_latency)
for i in range(nmasters)]
###
m_ca, m_ba, m_rca = self._split_master_addresses(controller_bits, bank_bits, rca_bits, cba_shift)
for nc, controller in enumerate(controllers):
if 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
for nb in range(nbanks):
bank = getattr(controller, "bank"+str(nb))
# arbitrate
rr = roundrobin.RoundRobin(nmasters, roundrobin.SP_CE)
self.submodules += rr
bank_selected = [cs & (ba == nb) for cs, ba in zip(controller_selected, m_ba)]
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]),
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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)]
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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(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(dw)
o_dat_we = Signal(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 controller_bits:
for master in self.masters:
controller_sel = Signal(controller_bits)
for nc, controller in enumerate(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(read_latency):
n_controller_sel = Signal(controller_bits)
self.sync += n_controller_sel.eq(controller_sel)
controller_sel = n_controller_sel
self.comb += master.dat_r.eq(Array(controllers)[controller_sel].dat_r)
else:
self.comb += [master.dat_r.eq(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(controller_bits + bank_bits)
rca = Signal(rca_bits)
cba_upper = cba_shift + controller_bits + bank_bits
self.comb += cba.eq(master.adr[cba_shift:cba_upper])
if cba_shift < 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 controller_bits:
ca = Signal(controller_bits)
ba = Signal(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
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class Initiator(Module):
def __init__(self, generator, bus):
self.generator = generator
self.bus = bus
self.transaction_start = 0
self.transaction = None
self.transaction_end = None
self.done = False
def do_simulation(self, s):
s.wr(self.bus.dat_w, 0)
s.wr(self.bus.dat_we, 0)
if not self.done:
if self.transaction is not None and s.rd(self.bus.ack):
s.wr(self.bus.stb, 0)
if isinstance(self.transaction, TRead):
self.transaction_end = s.cycle_counter + self.bus.read_latency
else:
self.transaction_end = s.cycle_counter + self.bus.write_latency - 1
if self.transaction is None or s.cycle_counter == self.transaction_end:
if self.transaction is not None:
self.transaction.latency = s.cycle_counter - self.transaction_start - 1
if isinstance(self.transaction, TRead):
self.transaction.data = s.rd(self.bus.dat_r)
else:
s.wr(self.bus.dat_w, self.transaction.data)
s.wr(self.bus.dat_we, self.transaction.sel)
try:
self.transaction = next(self.generator)
except StopIteration:
self.done = True
self.transaction = None
if self.transaction is not None:
self.transaction_start = s.cycle_counter
s.wr(self.bus.stb, 1)
s.wr(self.bus.adr, self.transaction.address)
if isinstance(self.transaction, TRead):
s.wr(self.bus.we, 0)
else:
s.wr(self.bus.we, 1)
class TargetModel:
def __init__(self):
self.last_bank = 0
def read(self, bank, address):
return 0
def write(self, bank, address, data, we):
pass
# Round-robin scheduling
def select_bank(self, pending_banks):
if not pending_banks:
return -1
self.last_bank += 1
if self.last_bank > max(pending_banks):
self.last_bank = 0
while self.last_bank not in pending_banks:
self.last_bank += 1
return self.last_bank
class Target(Module):
def __init__(self, model, *ifargs, **ifkwargs):
self.model = model
self.bus = Interface(*ifargs, **ifkwargs)
self.rd_pipeline = [None]*self.bus.read_latency
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self.wr_pipeline = [None]*(self.bus.write_latency + 1)
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def do_simulation(self, s):
# determine banks with pending requests
pending_banks = set()
for nb in range(self.bus.nbanks):
bank = getattr(self.bus, "bank"+str(nb))
if s.rd(bank.stb) and not s.rd(bank.ack):
pending_banks.add(nb)
# issue new transactions
selected_bank_n = self.model.select_bank(pending_banks)
for nb in range(self.bus.nbanks):
bank = getattr(self.bus, "bank"+str(nb))
if nb == selected_bank_n:
s.wr(bank.ack, 1)
else:
s.wr(bank.ack, 0)
rd_transaction = None
wr_transaction = None
if selected_bank_n >= 0:
selected_bank = getattr(self.bus, "bank"+str(selected_bank_n))
if s.rd(selected_bank.we):
wr_transaction = selected_bank_n, s.rd(selected_bank.adr)
else:
rd_transaction = selected_bank_n, s.rd(selected_bank.adr)
# data pipeline
self.rd_pipeline.append(rd_transaction)
self.wr_pipeline.append(wr_transaction)
done_rd_transaction = self.rd_pipeline.pop(0)
done_wr_transaction = self.wr_pipeline.pop(0)
if done_rd_transaction is not None:
s.wr(self.bus.dat_r, self.model.read(done_rd_transaction[0], done_rd_transaction[1]))
if done_wr_transaction is not None:
self.model.write(done_wr_transaction[0], done_wr_transaction[1],
s.rd(self.bus.dat_w), s.rd(self.bus.dat_we))