targets: Add new 1bitsquared_icebreaker_bitsy target

Most basic SoC ever but ... it runs

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

litex_boards/targets/1bitsquared_icebreaker_bitsy.py

+#!/usr/bin/env python3
+
+#
+# This file is part of LiteX-Boards.
+#
+# Copyright (c) 2019 Sean Cross <sean@xobs.io>
+# Copyright (c) 2018 David Shah <dave@ds0.me>
+# Copyright (c) 2020 Piotr Esden-Tempski <piotr@esden.net>
+# Copyright (c) 2020 Florent Kermarrec <florent@enjoy-digital.fr>
+# Copyright (c) 2021 Sylvain Munaut <tnt@246tNt.com>
+# SPDX-License-Identifier: BSD-2-Clause
+
+# This target file provides a minimal LiteX SoC for the iCEBreaker-bitsy with a CPU,
+# its ROM (in SPI Flash), its SRAM, close to the others LiteX targets.
+# For more complete example of LiteX SoC for the iCEBreaker-bitsy with more features and
+# documentation can be found, refer to :
+# https://github.com/icebreaker-fpga/icebreaker-litex-examples
+
+import os
+import argparse
+
+from migen import *
+from migen.genlib.resetsync import AsyncResetSynchronizer
+
+from litex_boards.platforms import icebreaker_bitsy
+
+from litex.soc.cores.ram import Up5kSPRAM
+from litex.soc.cores.spi_flash import SpiFlash
+from litex.soc.cores.clock import iCE40PLL
+from litex.soc.integration.soc_core import *
+from litex.soc.integration.soc import SoCRegion
+from litex.soc.integration.builder import *
+
+kB = 1024
+mB = 1024*kB
+
+# CRG ----------------------------------------------------------------------------------------------
+
+class _CRG(Module):
+    def __init__(self, platform, sys_clk_freq):
+        self.rst = Signal()
+        self.clock_domains.cd_sys = ClockDomain()
+        self.clock_domains.cd_por = ClockDomain(reset_less=True)
+
+        # # #
+
+        # Clk/Rst
+        clk12 = platform.request("clk12")
+        rst_n = platform.request("user_btn_n")
+
+        # Power On Reset
+        por_count = Signal(16, reset=2**16-1)
+        por_done  = Signal()
+        self.comb += self.cd_por.clk.eq(ClockSignal())
+        self.comb += por_done.eq(por_count == 0)
+        self.sync.por += If(~por_done, por_count.eq(por_count - 1))
+
+        # PLL
+        self.submodules.pll = pll = iCE40PLL(primitive="SB_PLL40_PAD")
+        self.comb += pll.reset.eq(~rst_n) # FIXME: Add proper iCE40PLL reset support and add back | self.rst.
+        pll.register_clkin(clk12, 12e6)
+        pll.create_clkout(self.cd_sys, sys_clk_freq, with_reset=False)
+        self.specials += AsyncResetSynchronizer(self.cd_sys, ~por_done | ~pll.locked)
+        platform.add_period_constraint(self.cd_sys.clk, 1e9/sys_clk_freq)
+
+# BaseSoC ------------------------------------------------------------------------------------------
+
+class BaseSoC(SoCCore):
+    mem_map = {**SoCCore.mem_map, **{"spiflash": 0x80000000}}
+    def __init__(self, bios_flash_offset, sys_clk_freq=int(24e6), revision="v1", **kwargs):
+        platform = icebreaker_bitsy.Platform(revision=revision)
+
+        # Disable Integrated ROM/SRAM since too large for iCE40 and UP5K has specific SPRAM.
+        kwargs["integrated_sram_size"] = 0
+        kwargs["integrated_rom_size"]  = 0
+
+        # Set CPU variant / reset address
+        kwargs["cpu_reset_address"] = self.mem_map["spiflash"] + bios_flash_offset
+
+        # SoCCore ----------------------------------------------------------------------------------
+        SoCCore.__init__(self, platform, sys_clk_freq,
+            ident          = "LiteX SoC on iCEBreaker-bitsy",
+            ident_version  = True,
+            **kwargs)
+
+        # CRG --------------------------------------------------------------------------------------
+        self.submodules.crg = _CRG(platform, sys_clk_freq)
+
+        # 128KB SPRAM (used as SRAM) ---------------------------------------------------------------
+        self.submodules.spram = Up5kSPRAM(size=128*kB)
+        self.bus.add_slave("sram", self.spram.bus, SoCRegion(size=128*kB))
+
+        # SPI Flash --------------------------------------------------------------------------------
+        self.add_spi_flash(mode="1x", dummy_cycles=8)
+
+        # Add ROM linker region --------------------------------------------------------------------
+        self.bus.add_region("rom", SoCRegion(
+            origin = self.mem_map["spiflash"] + bios_flash_offset,
+            size   = 32*kB,
+            linker = True)
+        )
+
+# Build --------------------------------------------------------------------------------------------
+
+def main():
+    parser = argparse.ArgumentParser(description="LiteX SoC on iCEBreaker")
+    parser.add_argument("--build",               action="store_true", help="Build bitstream")
+    parser.add_argument("--flash",               action="store_true", help="Flash bitstream and bios")
+    parser.add_argument("--sys-clk-freq",        default=24e6,        help="System clock frequency (default: 24MHz)")
+    parser.add_argument("--bios-flash-offset",   default=0xa0000,     help="BIOS offset in SPI Flash (default: 0xa0000)")
+    parser.add_argument("--revision",            default="v1",        help="Board revision 'v0' or 'v1'")
+    builder_args(parser)
+    soc_core_args(parser)
+    args = parser.parse_args()
+
+    soc = BaseSoC(
+        bios_flash_offset   = args.bios_flash_offset,
+        sys_clk_freq        = int(float(args.sys_clk_freq)),
+		revision            = args.revision,
+        **soc_core_argdict(args)
+    )
+    builder = Builder(soc, **builder_argdict(args))
+    builder.build(run=args.build)
+
+    if args.flash:
+        from litex.build.dfu import DFUProg
+        prog_gw = DFUProg(vid="1d50", pid="0x6146", alt=0)
+        prog_sw = DFUProg(vid="1d50", pid="0x6146", alt=1)
+
+        prog_gw.load_bitstream(os.path.join(builder.gateware_dir, soc.build_name + ".bin"), reset=False)
+        prog_sw.load_bitstream(os.path.join(builder.software_dir, 'bios/bios.bin'))
+
+if __name__ == "__main__":
+    main()