Merge pull request #303 from sergachev/master

sipeed_tang_nano_4k: add option to build with Gowin EMCU

litex_boards/targets/sipeed_tang_nano_4k.py

@@ -64,16 +64,18 @@ class _CRG(Module):
 # BaseSoC ------------------------------------------------------------------------------------------
 
 class BaseSoC(SoCCore):
-    mem_map = {**SoCCore.mem_map, **{"spiflash": 0x80000000}}
     def __init__(self, sys_clk_freq=int(27e6), with_hyperram=False, with_led_chaser=True, with_video_terminal=True, **kwargs):
         platform = tang_nano_4k.Platform()
 
-        # Put BIOS in SPIFlash to save BlockRAMs.
-        kwargs["integrated_rom_size"] = 0
-        kwargs["cpu_reset_address"]   = self.mem_map["spiflash"] + 0
-
-        kwargs["cpu_type"] = 'vexriscv'
-        kwargs["cpu_variant"] = 'minimal'
+        if 'cpu_type' in kwargs and kwargs['cpu_type'] == 'gowin_emcu':
+            kwargs['with_uart'] = False  # CPU has own UART
+            kwargs['integrated_sram_size'] = 0  # SRAM is directly attached to CPU
+            kwargs["integrated_rom_size"] = 0  # boot flash directly attached to CPU
+        else:
+            # Put BIOS in SPIFlash to save BlockRAMs.
+            self.mem_map = {**SoCCore.mem_map, **{"spiflash": 0x80000000}}
+            kwargs["integrated_rom_size"] = 0
+            kwargs["cpu_reset_address"]   = self.mem_map["spiflash"] + 0
 
         # SoCCore ----------------------------------------------------------------------------------
         SoCCore.__init__(self, platform, sys_clk_freq,
@@ -81,6 +83,9 @@ class BaseSoC(SoCCore):
             ident_version = True,
             **kwargs)
 
+        if self.cpu_type == 'vexriscv':
+            assert self.cpu_variant == 'minimal', 'use --cpu-variant=minimal to fit into number of BSRAMs'
+
         # CRG --------------------------------------------------------------------------------------
         self.submodules.crg = _CRG(platform, sys_clk_freq, with_video_pll=with_video_terminal)
 
@@ -89,12 +94,15 @@ class BaseSoC(SoCCore):
         from litespi.opcodes import SpiNorFlashOpCodes as Codes
         self.add_spi_flash(mode="1x", module=W25Q32(Codes.READ_1_1_1), with_master=False)
 
+        if self.cpu_type == 'gowin_emcu':
+            self.cpu.connect_uart(platform.request('serial'))
+        else:
         # Add ROM linker region --------------------------------------------------------------------
-        self.bus.add_region("rom", SoCRegion(
-            origin = self.mem_map["spiflash"] + 0,
-            size   = 64*kB,
-            linker = True)
-        )
+            self.bus.add_region("rom", SoCRegion(
+                origin = self.mem_map["spiflash"] + 0,
+                size   = 64*kB,
+                linker = True)
+            )
 
         # HyperRAM ---------------------------------------------------------------------------------
         if with_hyperram:
@@ -136,8 +144,12 @@ def main():
     soc_core_args(parser)
     args = parser.parse_args()
 
+    if args.cpu_type == 'gowin_emcu':
+        # FIXME: ARM software not supported yet
+        args.no_compile_software = True
+
     soc = BaseSoC(
-        sys_clk_freq      = int(float(args.sys_clk_freq)),
+        sys_clk_freq=int(float(args.sys_clk_freq)),
         **soc_core_argdict(args)
     )