From e8e4537e1482037e3b0c37baba09ab9fff0ae8d0 Mon Sep 17 00:00:00 2001
From: Florent Kermarrec <florent@enjoy-digital.fr>
Date: Mon, 10 Feb 2020 19:02:44 +0100
Subject: [PATCH] soc/add_sdram: avoid L2 cache when l2_cache_size == 0.

---
 litex/soc/integration/soc.py | 50 ++++++++++++++++++++----------------
 1 file changed, 28 insertions(+), 22 deletions(-)

diff --git a/litex/soc/integration/soc.py b/litex/soc/integration/soc.py
index 739901678..3cb2df8b0 100755
--- a/litex/soc/integration/soc.py
+++ b/litex/soc/integration/soc.py
@@ -944,29 +944,35 @@ class LiteXSoC(SoC):
                     base_address = origin)
                 self.submodules += wishbone.Converter(mem_wb, litedram_wb)
         elif self.with_wishbone:
-            # Insert L2 cache inbetween Wishbone bus and LiteDRAM
-            l2_cache_size = max(l2_cache_size, int(2*port.data_width/8)) # Use minimal size if lower
-            l2_cache_size = 2**int(log2(l2_cache_size))                  # Round to nearest power of 2
-            self.add_config("L2_SIZE", l2_cache_size)
-
-            # SoC <--> L2 Cache Wishbone interface -------------------------------------------------
+            # Wishbone Slave SDRAM interface -------------------------------------------------------
             wb_sdram = wishbone.Interface()
             self.bus.add_slave("main_ram", wb_sdram, SoCRegion(origin=origin, size=sdram_size))
 
-            # L2 Cache -----------------------------------------------------------------------------
-            l2_cache_data_width = max(port.data_width, l2_cache_min_data_width)
-            l2_cache = wishbone.Cache(
-                cachesize = l2_cache_size//4,
-                master    = wb_sdram,
-                slave     = wishbone.Interface(l2_cache_data_width),
-                reverse   = l2_cache_reverse)
-            # XXX Vivado workaround, Vivado is not able to map correctly our L2 cache.
-            from litex.build.xilinx.vivado import XilinxVivadoToolchain
-            if isinstance(self.platform.toolchain, XilinxVivadoToolchain):
-                from migen.fhdl.simplify import FullMemoryWE
-                self.submodules.l2_cache = FullMemoryWE()(l2_cache)
-            else:
-                self.submodules.l2_cache = l2_cache
+            if l2_cache_size != 0:
+                # Insert L2 cache inbetween Wishbone bus and LiteDRAM
+                l2_cache_size = max(l2_cache_size, int(2*port.data_width/8)) # Use minimal size if lower
+                l2_cache_size = 2**int(log2(l2_cache_size))                  # Round to nearest power of 2
+                self.add_config("L2_SIZE", l2_cache_size)
 
-            # L2 Cache <--> LiteDRAM bridge --------------------------------------------------------
-            self.submodules.wishbone_bridge = LiteDRAMWishbone2Native(self.l2_cache.slave, port)
+                # L2 Cache -------------------------------------------------------------------------
+                l2_cache_data_width = max(port.data_width, l2_cache_min_data_width)
+                l2_cache = wishbone.Cache(
+                    cachesize = l2_cache_size//4,
+                    master    = wb_sdram,
+                    slave     = wishbone.Interface(l2_cache_data_width),
+                    reverse   = l2_cache_reverse)
+                # XXX Vivado workaround, Vivado is not able to map correctly our L2 cache.
+                from litex.build.xilinx.vivado import XilinxVivadoToolchain
+                if isinstance(self.platform.toolchain, XilinxVivadoToolchain):
+                    from migen.fhdl.simplify import FullMemoryWE
+                    self.submodules.l2_cache = FullMemoryWE()(l2_cache)
+                else:
+                    self.submodules.l2_cache = l2_cache
+                # L2 Cache <--> LiteDRAM bridge ----------------------------------------------------
+                self.submodules.wishbone_bridge = LiteDRAMWishbone2Native(self.l2_cache.slave, port)
+            else:
+                self.add_config("L2_SIZE", l2_cache_size)
+                litedram_wb = wishbone.Interface(port.data_width)
+                self.submodules += wishbone.Converter(wb_sdram, litedram_wb)
+                # Wishbone Slave <--> LiteDRAM bridge ----------------------------------------------
+                self.submodules.wishbone_bridge = LiteDRAMWishbone2Native(litedram_wb, port)