gen/common: Introduce LiteXModule class to simplify Modules creation and avoid common mistakes.

LiteXModule can be used as a remplacement of Migen's Module and in this initial version:
- Automatically inherit from AutoCSR (Forgeting to inherit from AutoCSR on a Module was a common mistake).
- Simplify design creation with:
  - m.module_x  = .. equivalent of Migen's m.submodules.module_x = ..
  - m.special_x = .. equivalent of Migen's m.specials.special_x  = ..
  - m.cd_x      = .. equivalent of Migen's m.clock_domains.cd_x  = ..
  - m += module_x  equivalent of Migen's m.submodules += module_x.
  - m += special_x equivalent of Migen's m.specials += special_x.
  - m += cd_x  equivalent of Migen's m.clock_domains += cd_x.
-> Forgeting to attach a correctly a Sub-module/Special was a very common mistake and having to use
m.submodules., m.specials., m.clock_domains. was not natural.

litex/gen/common.py

@@ -1,11 +1,16 @@
 #
 # This file is part of LiteX.
 #
-# This file is Copyright (c) 2018 Florent Kermarrec <florent@enjoy-digital.fr>
+# This file is Copyright (c) 2018-2022 Florent Kermarrec <florent@enjoy-digital.fr>
 # SPDX-License-Identifier: BSD-2-Clause
 
 from migen import *
+from migen.fhdl.module import _ModuleProxy
+from migen.fhdl.specials import Special
 
+from litex.soc.interconnect.csr import AutoCSR
+
+# Bit/Bytes Reversing ------------------------------------------------------------------------------
 
 def reverse_bits(s):
     return s[::-1]
@@ -15,3 +20,42 @@ def reverse_bytes(s):
     n = (len(s) + 7)//8
     return Cat(*[s[i*8:min((i + 1)*8, len(s))]
         for i in reversed(range(n))])
+
+# LiteX Module -------------------------------------------------------------------------------------
+
+class LiteXModule(Module, AutoCSR):
+    def __setattr__(m, name, value):
+        # Migen:
+        if name in ["comb", "sync", "specials", "submodules", "clock_domains"]:
+            if not isinstance(value, _ModuleProxy):
+                raise AttributeError("Attempted to assign special Module property - use += instead")
+        # LiteX fix-up: Automatically collect specials/submodules/clock_domains:
+        # - m.module_x  = .. equivalent of Migen's m.submodules.module_x = ..
+        elif isinstance(value, Module)      and ((name, value) not in m._submodules):
+            setattr(m.submodules, name, value)
+        # - m.special_x = .. equivalent of Migen's m.specials.special_x  = ..
+        elif isinstance(value, Special)     and (value not in m._fragment.specials):
+            setattr(m.specials, name, value)
+        # - m.cd_x      = .. equivalent of Migen's m.clock_domains.cd_x  = ..
+        elif isinstance(value, ClockDomain) and (value not in m._fragment.clock_domains):
+            setattr(m.clock_domains, name, value)
+        # Else use default __setattr__.
+        else:
+            object.__setattr__(m, name, value)
+
+    # LiteX fix-up: Automatically collect specials/submodules/clock_domains:
+    def __iadd__(m, other):
+        # - m += module_x  equivalent of Migen's m.submodules += module_x.
+        if isinstance(other, Module):
+            print(other)
+            m.submodules += other
+        # - m += special_x  equivalent of Migen's m.specials += special_x.
+        elif isinstnace(other, Special):
+            m.specials += other
+        # - m += cd_x  equivalent of Migen's m.clock_domains += cd_x.
+        elif isinstance(other, ClockDomain):
+            m.clock_domains += other
+        # Else use default __iadd__.
+        else:
+            object.__iadd__(m, other)
+        return m

litex/soc/integration/soc.py

@@ -15,6 +15,7 @@ import datetime
 from math import log2, ceil
 
 from migen import *
+from litex.gen import LiteXModule
 
 from litex.soc.cores import cpu
 
@@ -766,7 +767,7 @@ class SoCController(Module, AutoCSR):
 
 # SoC ----------------------------------------------------------------------------------------------
 
-class SoC(Module):
+class SoC(LiteXModule):
     mem_map = {}
     def __init__(self, platform, sys_clk_freq,
         bus_standard         = "wishbone",