99 lines
2.9 KiB
Python
99 lines
2.9 KiB
Python
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from enum import Enum
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from collections import OrderedDict
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from nmigen import *
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from nmigen.utils import bits_for
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__all__ = ["CSRAccess", "CSR", "AutoCSR", "CSRFile"]
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class CSRAccess(Enum):
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RW = 0
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RO = 1
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class CSR(Record):
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def __init__(self, addr, description, name=None, src_loc_at=0):
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fields = []
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mask = 0
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offset = 0
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for fname, shape, access in description:
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if isinstance(shape, int):
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shape = shape, False
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width, signed = shape
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fields.append((fname, shape))
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if access is CSRAccess.RW:
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mask |= ((1 << width) - 1) << offset
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offset += width
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self.addr = addr
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self.mask = mask
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super().__init__([
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("r", fields),
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("w", fields),
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("re", 1),
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("we", 1),
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], name=name, src_loc_at=1 + src_loc_at)
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class AutoCSR():
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def iter_csrs(self):
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for v in vars(self).values():
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if isinstance(v, CSR):
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yield v
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elif hasattr(v, "iter_csrs"):
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yield from v.iter_csrs()
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class CSRFile(Elaboratable):
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def __init__(self, width=32, depth=2**12):
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self.width = width
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self.depth = depth
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self._csr_map = OrderedDict()
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self._read_ports = []
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self._write_ports = []
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def add_csrs(self, csrs):
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for csr in csrs:
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if not isinstance(csr, CSR):
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raise TypeError("Object {!r} is not a CSR".format(csr))
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if csr.addr in self._csr_map:
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raise ValueError("CSR address 0x{:x} has already been allocated"
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.format(csr.addr))
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self._csr_map[csr.addr] = csr
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def read_port(self):
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port = Record([("addr", bits_for(self.depth)), ("en", 1), ("data", self.width)], name="rp")
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self._read_ports.append(port)
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return port
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def write_port(self):
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port = Record([("addr", bits_for(self.depth)), ("en", 1), ("data", self.width)], name="wp")
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self._write_ports.append(port)
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return port
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def elaborate(self, platform):
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m = Module()
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for rp in self._read_ports:
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with m.Switch(rp.addr):
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for addr, csr in self._csr_map.items():
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with m.Case(addr):
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m.d.comb += [
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csr.re.eq(rp.en),
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rp.data.eq(csr.r)
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]
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for wp in self._write_ports:
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with m.Switch(wp.addr):
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for addr, csr in self._csr_map.items():
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with m.Case(addr):
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m.d.comb += csr.we.eq(wp.en)
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for i in range(self.width):
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rw = (1 << i) & csr.mask
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m.d.comb += csr.w[i].eq(wp.data[i] if rw else csr.r[i])
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return m
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