bank: support for atomic writes

This commit is contained in:
Sebastien Bourdeauducq 2012-10-08 18:43:18 +02:00
parent 24877f271b
commit e410973352
3 changed files with 54 additions and 23 deletions

View file

@ -6,7 +6,7 @@ from migen.bank.description import READ_ONLY, WRITE_ONLY
ninputs = 32
noutputs = 32
oreg = description.RegisterField("o", noutputs)
oreg = description.RegisterField("o", noutputs, atomic_write=True)
ireg = description.RegisterField("i", ninputs, READ_ONLY, WRITE_ONLY)
# input path

View file

@ -39,6 +39,11 @@ class Bank:
if len(bwra) > 1:
bwra.append(reg.re.eq(1))
bwcases.append(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.interface.we & self.interface.adr[:nbits] == i, *commit_instr))
else:
raise TypeError
if bwcases:
@ -59,10 +64,7 @@ class Bank:
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])])
brcases.append([Constant(i, BV(nbits)), self.interface.dat_r.eq(Cat(*brs))])
else:
raise TypeError
if brcases:

View file

@ -11,12 +11,13 @@ class RegisterRaw:
(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):
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(BV(self.size), reset=reset)
self.atomic_write = atomic_write
if self.access_bus == READ_ONLY and self.access_dev == WRITE_ONLY:
self.w = Signal(BV(self.size))
else:
@ -36,16 +37,27 @@ class RegisterFields:
self.re = re
class RegisterField(RegisterFields):
def __init__(self, name, size=1, access_bus=READ_WRITE, access_dev=READ_ONLY, reset=0):
self.field = Field(name, size, access_bus, access_dev, reset)
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, f, start, end):
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
self.storage = f.storage[start:end]
if mode == ALIAS_ATOMIC_HOLD:
self.storage = Signal(BV(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):
@ -57,28 +69,45 @@ def expand_description(description, busword):
d.append(reg)
elif isinstance(reg, RegisterFields):
f = []
size = 0
offset = 0
totalsize = 0
for field in reg.fields:
size += field.size
if size > busword:
offset += field.size
totalsize += field.size
if offset > busword:
# add padding
totalsize = sum([field.size for field in reg.fields])
padding = busword - (totalsize % busword)
if padding == busword:
padding = 0
size += padding
if padding != busword:
totalsize += padding
offset += padding
top = field.size
while size > busword:
slice1 = busword - size + top
slice2 = min(size - busword, busword)
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:
f.append(FieldAlias(field, top - slice1, top))
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))
f = [FieldAlias(field, top - slice2, top)]
alias = FieldAlias(mode, field, top - slice2, top, commit_list)
f = [alias]
if mode == ALIAS_ATOMIC_HOLD:
commit_list.append(alias)
top -= slice2
size -= busword
offset -= busword
else:
f.append(field)
if f: