litex/migen/bank/description.py

119 lines
3.4 KiB
Python

from migen.fhdl.structure import *
def regprefix(prefix, registers):
for register in registers:
register.name = prefix + register.name
return registers
class RegisterRaw:
def __init__(self, name, size=1):
self.name = name
self.size = size
self.re = Signal()
self.r = Signal(self.size)
self.w = Signal(self.size)
(READ_ONLY, WRITE_ONLY, READ_WRITE) = range(3)
class Field:
def __init__(self, name, size=1, access_bus=READ_WRITE, access_dev=READ_ONLY, reset=0, atomic_write=False):
self.name = name
self.size = size
self.access_bus = access_bus
self.access_dev = access_dev
self.storage = Signal(self.size, reset=reset)
self.atomic_write = atomic_write
if self.access_bus == READ_ONLY and self.access_dev == WRITE_ONLY:
self.w = Signal(self.size)
else:
if self.access_dev == READ_ONLY or self.access_dev == READ_WRITE:
self.r = Signal(self.size)
if self.access_dev == WRITE_ONLY or self.access_dev == READ_WRITE:
self.w = Signal(self.size)
self.we = Signal()
class RegisterFields:
def __init__(self, name, fields):
self.name = name
self.fields = fields
class RegisterField(RegisterFields):
def __init__(self, name, size=1, access_bus=READ_WRITE, access_dev=READ_ONLY, reset=0, atomic_write=False):
self.field = Field(name, size, access_bus, access_dev, reset, atomic_write)
super().__init__(name, [self.field])
(ALIAS_NON_ATOMIC, ALIAS_ATOMIC_HOLD, ALIAS_ATOMIC_COMMIT) = range(3)
class FieldAlias:
def __init__(self, mode, f, start, end, commit_list):
self.mode = mode
self.size = end - start
self.access_bus = f.access_bus
self.access_dev = f.access_dev
if mode == ALIAS_ATOMIC_HOLD:
self.storage = Signal(end-start, name="atomic_hold")
self.commit_to = f.storage[start:end]
else:
self.storage = f.storage[start:end]
if mode == ALIAS_ATOMIC_COMMIT:
self.commit_list = commit_list
else:
self.commit_list = []
# device access is through the original field
def expand_description(description, busword):
d = []
for reg in description:
if isinstance(reg, RegisterRaw):
if reg.size > busword:
raise ValueError("Raw register larger than a bus word")
d.append(reg)
elif isinstance(reg, RegisterFields):
f = []
offset = 0
totalsize = 0
for field in reg.fields:
offset += field.size
totalsize += field.size
if offset > busword:
# add padding
padding = busword - (totalsize % busword)
if padding != busword:
totalsize += padding
offset += padding
top = field.size
commit_list = []
while offset > busword:
if field.atomic_write:
if offset - busword > busword:
mode = ALIAS_ATOMIC_HOLD
else:
# last iteration
mode = ALIAS_ATOMIC_COMMIT
else:
mode = ALIAS_NON_ATOMIC
slice1 = busword - offset + top
slice2 = min(offset - busword, busword)
if slice1:
alias = FieldAlias(mode, field, top - slice1, top, commit_list)
f.append(alias)
if mode == ALIAS_ATOMIC_HOLD:
commit_list.append(alias)
top -= slice1
d.append(RegisterFields(reg.name, f))
alias = FieldAlias(mode, field, top - slice2, top, commit_list)
f = [alias]
if mode == ALIAS_ATOMIC_HOLD:
commit_list.append(alias)
top -= slice2
offset -= busword
else:
f.append(field)
if f:
d.append(RegisterFields(reg.name, f))
else:
raise TypeError
return d