Merge pull request #40 from mithro/or1k-linux

cpu: Adding "variant" support.

litex/soc/cores/cpu/lm32/core.py

@@ -6,7 +6,8 @@ from litex.soc.interconnect import wishbone
 
 
 class LM32(Module):
-    def __init__(self, platform, eba_reset):
+    def __init__(self, platform, eba_reset, variant=None):
+        assert variant == None, "No lm32 variants currently supported."
         self.ibus = i = wishbone.Interface()
         self.dbus = d = wishbone.Interface()
         self.interrupt = Signal(32)

litex/soc/cores/cpu/mor1kx/core.py

@@ -6,16 +6,15 @@ from litex.soc.interconnect import wishbone
 
 
 class MOR1KX(Module):
-    def __init__(self, platform, reset_pc):
+    def __init__(self, platform, reset_pc, variant=None):
+        assert variant in (None, "linux"), "Unsupported variant %s" % variant
         self.ibus = i = wishbone.Interface()
         self.dbus = d = wishbone.Interface()
         self.interrupt = Signal(32)
 
         # # #
 
-        i_adr_o = Signal(32)
-        d_adr_o = Signal(32)
-        self.specials += Instance("mor1kx",
+        cpu_args = dict(
             p_FEATURE_INSTRUCTIONCACHE="ENABLED",
             p_OPTION_ICACHE_BLOCK_WIDTH=4,
             p_OPTION_ICACHE_SET_WIDTH=8,
@@ -39,6 +38,35 @@ class MOR1KX(Module):
             p_OPTION_RESET_PC=reset_pc,
             p_IBUS_WB_TYPE="B3_REGISTERED_FEEDBACK",
             p_DBUS_WB_TYPE="B3_REGISTERED_FEEDBACK",
+        )
+
+        if variant == None:
+            # Use the default configuration
+            pass
+        elif variant == "linux":
+            cpu_args.update(dict(
+                # Linux needs the memory management units.
+                p_FEATURE_IMMU="ENABLED",
+                p_FEATURE_DMMU="ENABLED",
+                # FIXME: Currently we need the or1k timer when we should be
+                # using the litex timer.
+                p_FEATURE_TIMER="ENABLED",
+            ))
+            # FIXME: Check if these are needed?
+            use_defaults = (
+                "p_FEATURE_SYSCALL", "p_FEATURE_TRAP", "p_FEATURE_RANGE",
+                "p_FEATURE_OVERFLOW",
+            )
+            for to_remove in use_defaults:
+                del cpu_args[to_remove]
+
+        else:
+            assert False, "Unsupported variant %s" % variant
+
+        i_adr_o = Signal(32)
+        d_adr_o = Signal(32)
+        self.specials += Instance("mor1kx",
+            **cpu_args,
 
             i_clk=ClockSignal(),
             i_rst=ResetSignal(),

litex/soc/integration/soc_core.py

@@ -60,7 +60,7 @@ class SoCCore(Module):
         "csr":      0x60000000,  # (default shadow @0xe0000000)
     }
     def __init__(self, platform, clk_freq,
-                cpu_type="lm32", cpu_reset_address=0x00000000,
+                cpu_type="lm32", cpu_reset_address=0x00000000, cpu_variant=None,
                 integrated_rom_size=0, integrated_rom_init=[],
                 integrated_sram_size=4096,
                 integrated_main_ram_size=0, integrated_main_ram_init=[],
@@ -76,6 +76,7 @@ class SoCCore(Module):
         self.clk_freq = clk_freq
 
         self.cpu_type = cpu_type
+        self.cpu_variant = cpu_variant
         if integrated_rom_size:
             cpu_reset_address = self.mem_map["rom"]
         self.cpu_reset_address = cpu_reset_address
@@ -103,16 +104,18 @@ class SoCCore(Module):
 
         if cpu_type is not None:
             if cpu_type == "lm32":
-                self.add_cpu_or_bridge(lm32.LM32(platform, self.cpu_reset_address))
+                self.add_cpu_or_bridge(lm32.LM32(platform, self.cpu_reset_address, self.cpu_variant))
             elif cpu_type == "or1k":
-                self.add_cpu_or_bridge(mor1kx.MOR1KX(platform, self.cpu_reset_address))
+                self.add_cpu_or_bridge(mor1kx.MOR1KX(platform, self.cpu_reset_address, self.cpu_variant))
             elif cpu_type == "riscv32":
-                self.add_cpu_or_bridge(picorv32.PicoRV32(platform, self.cpu_reset_address))
+                self.add_cpu_or_bridge(picorv32.PicoRV32(platform, self.cpu_reset_address, self.cpu_variant))
             else:
                 raise ValueError("Unsupported CPU type: {}".format(cpu_type))
             self.add_wb_master(self.cpu_or_bridge.ibus)
             self.add_wb_master(self.cpu_or_bridge.dbus)
         self.config["CPU_TYPE"] = str(cpu_type).upper()
+        if self.cpu_variant:
+            self.config["CPU_VARIANT"] = str(cpu_type).upper()
 
         if integrated_rom_size:
             self.submodules.rom = wishbone.SRAM(integrated_rom_size, read_only=True, init=integrated_rom_init)