gen: In conjunction with the corresponding changes in litex itself, this will allow us to generate a more useful standalone litedram core.

The CSR alignment and base can be specified (which mostly affects
the generation of csr.h) andwe stop trying to copy the init code
that we haven't generated

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

litedram/gen.py

@@ -248,9 +248,11 @@ class LiteDRAMCore(SoCSDRAM):
     def __init__(self, platform, core_config, **kwargs):
         platform.add_extension(get_common_ios())
         sys_clk_freq = core_config["sys_clk_freq"]
+        csr_align = core_config.get("csr_port_align", "32")
         SoCSDRAM.__init__(self, platform, sys_clk_freq,
             cpu_type=core_config["cpu"],
             l2_size=16*core_config["sdram_module_nb"],
+            csr_alignment=csr_align,
             **kwargs)
 
         # crg
@@ -303,6 +305,9 @@ class LiteDRAMCore(SoCSDRAM):
                 csr_port.dat_w.eq(_csr_port_io.dat_w),
                 _csr_port_io.dat_r.eq(csr_port.dat_r),
             ]
+            if self.cpu_type == None:
+                csr_base = core_config.get("csr_base", 0)
+                self.shadow_base = csr_base;
 
         # user port
         self.comb += [
@@ -450,6 +455,7 @@ def main():
         with open(filename, 'w') as file:
             file.write(filedata)
 
+    if soc.cpu_type is not None:
         init_filename = "mem.init"
         os.system("mv build/gateware/{} build/gateware/litedram_core.init".format(init_filename))
         replace_in_file("build/gateware/litedram_core.v", init_filename, "litedram_core.init")