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add wishbone components

This commit is contained in:
Sebastien Bourdeauducq 2019-05-02 12:53:08 +08:00
parent 88db84cfd7
commit 70638e6d87
2 changed files with 210 additions and 20 deletions
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20
heavycomps/heavycomps/roundrobin.py
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from nmigen import *
class RoundRobin(Elaboratable):
def __init__(self, n):
self.n = n
self.request = Signal(n)
self.grant = Signal(max=n)
def elaborate(self, platform):
m = Module()
with m.Switch(self.grant):
for i in range(self.n):
with m.Case(i):
with m.If(~self.request[i]):
for j in reversed(range(i+1, i+self.n)):
t = j % self.n
with m.If(self.request[t]):
m.d.sync += self.grant.eq(t)
return m

210
heavycomps/heavycomps/wishbone.py Normal file
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from enum import Enum
from functools import reduce
from operator import or_
from nmigen import *
from nmigen.hdl.rec import *
__all__ = ["Cycle", "Interface", "Arbiter", "Decoder", "InterconnectShared"]
class Cycle(Enum):
CLASSIC = 0
CONSTANT = 1
INCREMENT = 2
END = 7
wishbone_layout = [
("adr", 30, DIR_FANOUT),
("dat_w", 32, DIR_FANOUT),
("dat_r", 32, DIR_FANIN),
("sel", 4, DIR_FANOUT),
("cyc", 1, DIR_FANOUT),
("stb", 1, DIR_FANOUT),
("ack", 1, DIR_FANIN),
("we", 1, DIR_FANOUT),
("cti", 3, DIR_FANOUT),
("bte", 2, DIR_FANOUT),
("err", 1, DIR_FANIN)
]
class Interface(Record):
def __init__(self):
Record.__init__(self, wishbone_layout)
def _do_transaction(self):
yield self.cyc.eq(1)
yield self.stb.eq(1)
yield
while not (yield self.ack):
yield
yield self.cyc.eq(0)
yield self.stb.eq(0)
def write(self, adr, dat, sel=None):
if sel is None:
sel = 2**len(self.sel) - 1
yield self.adr.eq(adr)
yield self.dat_w.eq(dat)
yield self.sel.eq(sel)
yield self.we.eq(1)
yield from self._do_transaction()
def read(self, adr):
yield self.adr.eq(adr)
yield self.we.eq(0)
yield from self._do_transaction()
return (yield self.dat_r)
class SRAM(Elaboratable):
def __init__(self, mem, read_only=False, bus=None):
self.mem = mem
self.read_only = read_only
if bus is None:
bus = Interface()
self.bus = bus
def elaborate(self, platform):
m = Module()
if self.mem.width > len(self.bus.dat_r):
raise NotImplementedError
# read
m.submodules.rdport = rdport = self.mem.read_port()
m.d.comb += [
rdport.addr.eq(self.bus.adr[:len(rdport.addr)]),
self.bus.dat_r.eq(rdport.data)
]
# write
if not self.read_only:
m.submodules.wrport = wrport = self.mem.write_port(granularity=8)
m.d.comb += [
wrport.addr.eq(self.bus.adr[:len(rdport.addr)]),
wrport.data.eq(self.bus.dat_w)
]
for i in range(4):
m.d.comb += wrport.en[i].eq(self.bus.cyc & self.bus.stb & self.bus.we & self.bus.sel[i])
# generate ack
m.d.sync += self.bus.ack.eq(0)
with m.If(self.bus.cyc & self.bus.stb & ~self.bus.ack):
m.d.sync += self.bus.ack.eq(1)
return m
class RoundRobin(Elaboratable):
def __init__(self, n):
self.n = n
self.request = Signal(n)
self.grant = Signal(max=n)
def elaborate(self, platform):
m = Module()
with m.Switch(self.grant):
for i in range(self.n):
with m.Case(i):
with m.If(~self.request[i]):
for j in reversed(range(i+1, i+self.n)):
t = j % self.n
with m.If(self.request[t]):
m.d.sync += self.grant.eq(t)
return m
class Arbiter(Elaboratable):
def __init__(self, masters, target):
self.masters = masters
self.target = target
def elaborate(self, platform):
m = Module()
m.submodules.rr = rr = RoundRobin(len(self.masters))
# mux master->target signals
for name, size, direction in wishbone_layout:
if direction == DIR_FANOUT:
choices = Array(getattr(m, name) for m in self.masters)
m.d.comb += getattr(self.target, name).eq(choices[rr.grant])
# connect target->master signals
for name, size, direction in wishbone_layout:
if direction == DIR_FANIN:
source = getattr(self.target, name)
for i, master in enumerate(self.masters):
dest = getattr(master, name)
if name == "ack" or name == "err":
m.d.comb += dest.eq(source & (rr.grant == i))
else:
m.d.comb += dest.eq(source)
# connect bus requests to round-robin selector
reqs = [m.cyc & ~m.ack for m in self.masters]
m.d.comb += rr.request.eq(Cat(*reqs))
return m
class Decoder(Elaboratable):
def __init__(self, master, targets, register=False):
self.master = master
self.targets = targets
self.register = register
def elaborate(self, platform):
m = Module()
nt = len(self.targets)
target_sel = Signal(nt)
target_sel_r = Signal(nt)
# decode target addresses
for i, (fun, bus) in enumerate(self.targets):
m.d.comb += target_sel[i].eq(fun(self.master.adr))
if self.register:
m.d.sync += target_sel_r.eq(target_sel)
else:
m.d.comb += target_sel_r.eq(target_sel)
# connect master->targets signals except cyc
for target in self.targets:
for name, size, direction in wishbone_layout:
if direction == DIR_FANOUT and name != "cyc":
m.d.comb += getattr(target[1], name).eq(getattr(self.master, name))
# combine cyc with target selection signals
for i, target in enumerate(self.targets):
m.d.comb += target[1].cyc.eq(self.master.cyc & target_sel[i])
# generate master ack (resp. err) by ORing all target acks (resp. errs)
m.d.comb += [
self.master.ack.eq(reduce(or_, [target[1].ack for target in self.targets])),
self.master.err.eq(reduce(or_, [target[1].err for target in self.targets]))
]
# mux (1-hot) target data return
masked = [Repl(target_sel_r[i], len(self.master.dat_r)) & self.targets[i][1].dat_r for i in range(nt)]
m.d.comb += self.master.dat_r.eq(reduce(or_, masked))
return m
class InterconnectShared(Module):
def __init__(self, masters, targets, register=False):
self.masters = masters
self.targets = targets
self.register = register
def elaborate(self, platform):
m = Module()
shared = Interface()
m.submodules.arbiter = Arbiter(self.masters, shared)
m.submodules.decoder = Decoder(shared, self.targets, self.register)
return m