litex/migen/bank/csrgen.py

87 lines
2.8 KiB
Python

from migen.fhdl.structure import *
from migen.bus.csr import *
from migen.bank.description import *
class Bank:
def __init__(self, description, address=0, interface=None):
self.description = description
self.address = address
if interface is None:
interface = Interface()
self.interface = interface
def get_fragment(self):
comb = []
sync = []
sel = Signal()
comb.append(sel.eq(self.interface.adr[9:] == Constant(self.address, BV(5))))
desc_exp = expand_description(self.description, 8)
nbits = bits_for(len(desc_exp)-1)
# Bus writes
bwcases = []
for i, reg in enumerate(desc_exp):
if isinstance(reg, RegisterRaw):
comb.append(reg.r.eq(self.interface.dat_w[:reg.size]))
comb.append(reg.re.eq(sel & \
self.interface.we & \
(self.interface.adr[:nbits] == Constant(i, BV(nbits)))))
elif isinstance(reg, RegisterFields):
sync.append(reg.re.eq(0))
bwra = [Constant(i, BV(nbits))]
offset = 0
for field in reg.fields:
if field.access_bus == WRITE_ONLY or field.access_bus == READ_WRITE:
bwra.append(field.storage.eq(self.interface.dat_w[offset:offset+field.size]))
offset += field.size
if len(bwra) > 1:
bwra.append(reg.re.eq(1))
bwcases.append(bwra)
else:
raise TypeError
if bwcases:
sync.append(If(sel & self.interface.we, Case(self.interface.adr[:nbits], *bwcases)))
# Bus reads
brcases = []
for i, reg in enumerate(desc_exp):
if isinstance(reg, RegisterRaw):
brcases.append([Constant(i, BV(nbits)), self.interface.dat_r.eq(reg.w)])
elif isinstance(reg, RegisterFields):
brs = []
reg_readable = False
for field in reg.fields:
if field.access_bus == READ_ONLY or field.access_bus == READ_WRITE:
brs.append(field.storage)
reg_readable = True
else:
brs.append(Constant(0, BV(field.size)))
if reg_readable:
if len(brs) > 1:
brcases.append([Constant(i, BV(nbits)), self.interface.dat_r.eq(Cat(*brs))])
else:
brcases.append([Constant(i, BV(nbits)), self.interface.dat_r.eq(brs[0])])
else:
raise TypeError
if brcases:
sync.append(self.interface.dat_r.eq(Constant(0, BV(8))))
sync.append(If(sel, Case(self.interface.adr[:nbits], *brcases)))
else:
comb.append(self.interface.dat_r.eq(Constant(0, BV(8))))
# Device access
for reg in self.description:
if isinstance(reg, RegisterFields):
for field in reg.fields:
if field.access_bus == READ_ONLY and field.access_dev == WRITE_ONLY:
comb.append(field.storage.eq(field.w))
else:
if field.access_dev == READ_ONLY or field.access_dev == READ_WRITE:
comb.append(field.r.eq(field.storage))
if field.access_dev == WRITE_ONLY or field.access_dev == READ_WRITE:
sync.append(If(field.we, field.storage.eq(field.w)))
return Fragment(comb, sync)