From 78bdde04246710afde40c7e814e2946f02ca02bf Mon Sep 17 00:00:00 2001
From: Florent Kermarrec <florent@enjoy-digital.fr>
Date: Mon, 17 May 2021 10:01:41 +0200
Subject: [PATCH] cpu/vexriscv: Simplify CFU integration, use Cfu.v as default
 CFU when not specified and rename argument to --cpu-cfu.

---
 CHANGES                              |  2 +-
 litex/soc/cores/cpu/vexriscv/core.py | 11 +++++++++--
 litex/soc/integration/soc_core.py    | 13 ++++---------
 3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/CHANGES b/CHANGES
index 7a138c5fa..145609b90 100644
--- a/CHANGES
+++ b/CHANGES
@@ -7,7 +7,7 @@
 
 	[> Added Features
 	-----------------
-	-
+	- cpu/vexriscv: Add CFU support.
 
 	[> API changes/Deprecation
 	--------------------------
diff --git a/litex/soc/cores/cpu/vexriscv/core.py b/litex/soc/cores/cpu/vexriscv/core.py
index c836d1f72..45cd811e2 100644
--- a/litex/soc/cores/cpu/vexriscv/core.py
+++ b/litex/soc/cores/cpu/vexriscv/core.py
@@ -101,7 +101,7 @@ class VexRiscv(CPU, AutoCSR):
     gcc_triple           = CPU_GCC_TRIPLE_RISCV32
     linker_output_format = "elf32-littleriscv"
     nop                  = "nop"
-    io_regions           = {0x80000000: 0x80000000} # origin, length
+    io_regions           = {0x80000000: 0x80000000} # Origin, Length
 
     # Memory Mapping.
     @property
@@ -121,7 +121,7 @@ class VexRiscv(CPU, AutoCSR):
         flags += " -D__vexriscv__"
         return flags
 
-    def __init__(self, platform, variant="standard", with_timer=False):
+    def __init__(self, platform, variant="standard", with_timer=False, cfu=None):
         self.platform         = platform
         self.variant          = variant
         self.human_name       = CPU_VARIANTS.get(variant, "VexRiscv")
@@ -174,6 +174,9 @@ class VexRiscv(CPU, AutoCSR):
         if "debug" in variant:
             self.add_debug()
 
+        if "cfu" in variant:
+            self.add_cfu(cfu_filename="Cfu.v" if cfu is None else cfu)
+
     def set_reset_address(self, reset_address):
         assert not hasattr(self, "reset_address")
         self.reset_address = reset_address
@@ -268,6 +271,10 @@ class VexRiscv(CPU, AutoCSR):
         )
 
     def add_cfu(self, cfu_filename):
+        # Check CFU presence.
+        if not os.path.exists(cfu_filename):
+            raise OSError(f"Unable to find VexRiscv CFU plugin {cfu_filename}.")
+
         # CFU Layout.
         cfu_bus_layout = [
             ("cmd", [
diff --git a/litex/soc/integration/soc_core.py b/litex/soc/integration/soc_core.py
index 830a9ab3e..03a233e1c 100644
--- a/litex/soc/integration/soc_core.py
+++ b/litex/soc/integration/soc_core.py
@@ -71,6 +71,7 @@ class SoCCore(LiteXSoC):
         cpu_reset_address        = None,
         cpu_variant              = None,
         cpu_cls                  = None,
+        cpu_cfu                  = None,
 
         # CFU parameters
         cfu_filename             = None,
@@ -186,8 +187,9 @@ class SoCCore(LiteXSoC):
         self.add_cpu(
             name          = str(cpu_type),
             variant       = "standard" if cpu_variant is None else cpu_variant,
+            reset_address = None if integrated_rom_size else cpu_reset_address,
             cls           = cpu_cls,
-            reset_address = None if integrated_rom_size else cpu_reset_address)
+            cfu           = cpu_cfu)
 
         # Add User's interrupts
         if self.irq.enabled:
@@ -220,11 +222,6 @@ class SoCCore(LiteXSoC):
             if timer_uptime:
                 self.timer0.add_uptime()
 
-        # Add CFU
-        if cfu_filename:
-            assert(cpu_type == "vexriscv")
-            self.cpu.add_cfu(cfu_filename=cfu_filename)
-
     # Methods --------------------------------------------------------------------------------------
 
     def add_interrupt(self, interrupt_name, interrupt_id=None, use_loc_if_exists=False):
@@ -300,6 +297,7 @@ def soc_core_args(parser):
     parser.add_argument("--cpu-type",          default=None,                     help="Select CPU: {}, (default=vexriscv).".format(", ".join(iter(cpu.CPUS.keys()))))
     parser.add_argument("--cpu-variant",       default=None,                     help="CPU variant (default=standard).")
     parser.add_argument("--cpu-reset-address", default=None,      type=auto_int, help="CPU reset address (default=None : Boot from Integrated ROM).")
+    parser.add_argument("--cpu-cfu",           default=None,                     help="Optional CPU CFU file/instance to add to the CPU.")
 
     # Controller parameters
     parser.add_argument("--no-ctrl", action="store_true", help="Disable Controller (default=False).")
@@ -337,9 +335,6 @@ def soc_core_args(parser):
     # L2 Cache
     parser.add_argument("--l2-size",           default=8192, type=auto_int, help="L2 cache size (default=8192).")
 
-    # CFU
-    parser.add_argument("--cfu-filename",      default=None,                help="CFU verilog filename.")
-
 def soc_core_argdict(args):
     r = dict()
     for a in inspect.getargspec(SoCCore.__init__).args: