litex/migen/bank/csrgen.py

85 lines
2.6 KiB
Python

from migen.fhdl.structure import *
from migen.bus import csr
from migen.bank.description import *
class Bank:
def __init__(self, description, address=0, bus=csr.Interface()):
self.description = description
self.address = address
self.bus = bus
def get_fragment(self):
comb = []
sync = []
sel = Signal()
comb.append(sel.eq(self.bus.adr[9:] == self.address))
desc_exp = expand_description(self.description, csr.data_width)
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.bus.dat_w[:reg.size]))
comb.append(reg.re.eq(sel & \
self.bus.we & \
(self.bus.adr[:nbits] == i)))
elif isinstance(reg, RegisterFields):
bwra = []
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.bus.dat_w[offset:offset+field.size]))
offset += field.size
if bwra:
bwcases[i] = bwra
# commit atomic writes
for field in reg.fields:
if isinstance(field, FieldAlias) and field.commit_list:
commit_instr = [hf.commit_to.eq(hf.storage) for hf in field.commit_list]
sync.append(If(sel & self.bus.we & self.bus.adr[:nbits] == i, *commit_instr))
else:
raise TypeError
if bwcases:
sync.append(If(sel & self.bus.we, Case(self.bus.adr[:nbits], bwcases)))
# Bus reads
brcases = {}
for i, reg in enumerate(desc_exp):
if isinstance(reg, RegisterRaw):
brcases[i] = [self.bus.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(Replicate(0, field.size))
if reg_readable:
brcases[i] = [self.bus.dat_r.eq(Cat(*brs))]
else:
raise TypeError
if brcases:
sync.append(self.bus.dat_r.eq(0))
sync.append(If(sel, Case(self.bus.adr[:nbits], brcases)))
else:
comb.append(self.bus.dat_r.eq(0))
# 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)