Add support for EBAZ4205 'Development' Board

Usage:

```
./ebaz4205.py --cpu-type=vexriscv --build --load
```

```
$ pwd
litex-boards/litex_boards/targets
```

Tip: Use `GTKTerm` to connect to /dev/ttyUSB0 (usually) and interact
with the LiteX BIOS.

References:

- https://github.com/fusesoc/blinky#ebaz4205-development-board
- https://github.com/olofk/serv/#ebaz4205-development-board
- https://github.com/xjtuecho/EBAZ4205#ebaz4205
- https://github.com/nmigen/nmigen-boards/pull/180 (merged)
- https://github.com/olofk/corescore/pull/33
- The existing 'Zybo Z7' example

Note: The `PS7` stuff remains untested via LiteX for now.

README.md

@@ -106,12 +106,13 @@ PCIe accelerators boards that you could use to accelerate your applications, Lit
 Repurposed FPGA hardware that has been "documented" by enthusiasts :), allows you to discover FPGAs for very cheap (starting at 15$)!
 
 | Name         | FPGA Family         | FPGA device   | Sys-Clk   | TTY  |       DRAM         |       Ethernet     |    Flash    |
-|--------------|---------------------|---------------|----------|------|--------------------|--------------------|-------------|
+|--------------|---------------------|---------------|-----------|------|--------------------|--------------------|-------------|
 | SDS1104X-E   | Xilinx Zynq         | XC7Z020       |  100MHz   | Eth  | 32-bit 256MB DDR3  | 100Mbps MII        |      ?      |
 | Colorlight5A | Lattice ECP5        | LFE5U-25F     |   60MHz   | IOs  | 32-bit 8MB SDR     | 2x 1Gbps RGMII     |   4MB QSPI  |
 | Linsn RV901  | Xilinx Spartan6     | XC6SLX16      |   75MHz   | IOs  | 32-bit 8MB SDR     | 2x 1Gbps RGMII     |   4MB QSPI  |
 | PanoLogic G2 | Xilinx Spartan6     | XC6SLX100-150 |   50MHz   | IOs  | 32-bit 128MB DDR2  | 1Gbps GMII         |  16MB QSPI  |
 | Camlink-4K   | Lattice ECP5        | LFE5U-25F     |   81MHz   | IOs  | 16-bit 128MB DDR3  |        No          |   ?MB QSPI  |
+| EBAZ4205     | Xilinx Zynq         | XC7Z010 (28k) | 33.333MHz | IOs  | 256MB DDR3         | 100Mbps RMII       |  128MB NAND |
 
 The Colorlight5A is a very nice board to start with, cheap, powerful, easy to use with the open-source toolchain, you can find a specific LiteX project [here](https://github.com/enjoy-digital/colorlite)
 

litex_boards/platforms/ebaz4205.py

@@ -0,0 +1,84 @@
+#
+# This file is part of LiteX-Boards.
+#
+# Copyright (c) 2019-2020 Florent Kermarrec <florent@enjoy-digital.fr>
+# Copyright (c) 2021 Dhiru Kholia <dhiru.kholia@gmail.com>
+# SPDX-License-Identifier: BSD-2-Clause
+
+from litex.build.generic_platform import *
+from litex.build.xilinx import XilinxPlatform, VivadoProgrammer
+from litex.build.xilinx.programmer import XC3SProg
+
+# IOs ----------------------------------------------------------------------------------------------
+
+_io = [
+    # Clk / Rst
+    ("clk33_333", 0, Pins("N18"), IOStandard("LVCMOS33")),
+
+    # Leds
+    ("user_led", 0, Pins("W14"), IOStandard("LVCMOS33")),
+    ("user_led", 1, Pins("W13"), IOStandard("LVCMOS33")),
+
+    # Serial
+    ("serial", 0,
+        Subsignal("tx", Pins("B20")),
+        Subsignal("rx", Pins("B19")),
+        IOStandard("LVCMOS33")
+    ),
+]
+
+# This is currently untested on this EBAZ4205 board
+_ps7_io = [
+    # PS7
+    ("ps7_clk",   0, Pins(1)),
+    ("ps7_porb",  0, Pins(1)),
+    ("ps7_srstb", 0, Pins(1)),
+    ("ps7_mio",   0, Pins(54)),
+    ("ps7_ddram", 0,
+        Subsignal("addr",    Pins(15)),
+        Subsignal("ba",      Pins(3)),
+        Subsignal("cas_n",   Pins(1)),
+        Subsignal("ck_n",    Pins(1)),
+        Subsignal("ck_p",    Pins(1)),
+        Subsignal("cke",     Pins(1)),
+        Subsignal("cs_n",    Pins(1)),
+        Subsignal("dm",      Pins(4)),
+        Subsignal("dq",      Pins(32)),
+        Subsignal("dqs_n",   Pins(4)),
+        Subsignal("dqs_p",   Pins(4)),
+        Subsignal("odt",     Pins(1)),
+        Subsignal("ras_n",   Pins(1)),
+        Subsignal("reset_n", Pins(1)),
+        Subsignal("we_n",    Pins(1)),
+        Subsignal("vrn",     Pins(1)),
+        Subsignal("vrp",     Pins(1)),
+    ),
+]
+
+# Connectors ---------------------------------------------------------------------------------------
+
+_connectors = [
+]
+
+# Platform -----------------------------------------------------------------------------------------
+
+class Platform(XilinxPlatform):
+    default_clk_name   = "clk33_333"
+    default_clk_period = 1e9/33.333e6
+
+    def __init__(self):
+        XilinxPlatform.__init__(self, "xc7z010-clg400-1", _io,  _connectors, toolchain="vivado")
+        self.add_extension(_ps7_io)
+
+    def create_programmer(self):
+        return VivadoProgrammer()
+
+    """
+    # We will like to use this later - Vivado is slow!
+    def create_programmer(self):
+        return XC3SProg(cable="ftdi")
+    """
+
+    def do_finalize(self, fragment):
+        XilinxPlatform.do_finalize(self, fragment)
+        self.add_period_constraint(self.lookup_request("clk33_333", loose=True), 1e9/33.333e6)

litex_boards/targets/ebaz4205.py

@@ -0,0 +1,102 @@
+#!/usr/bin/env python3
+
+#
+# This file is part of LiteX-Boards.
+#
+# Copyright (c) 2019-2020 Florent Kermarrec <florent@enjoy-digital.fr>,
+# Copyright (c) 2021 Dhiru Kholia <dhiru.kholia@gmail.com>,
+# SPDX-License-Identifier: BSD-2-Clause
+
+import os
+import argparse
+
+from migen import *
+
+from litex_boards.platforms import ebaz4205
+from litex.build.xilinx.vivado import vivado_build_args, vivado_build_argdict
+
+from litex.soc.interconnect import axi
+from litex.soc.interconnect import wishbone
+
+from litex.soc.cores.clock import *
+from litex.soc.integration.soc_core import *
+from litex.soc.integration.builder import *
+from litex.soc.cores.led import LedChaser
+
+# CRG ----------------------------------------------------------------------------------------------
+
+class _CRG(Module):
+    def __init__(self, platform, sys_clk_freq, use_ps7_clk=False):
+        self.rst = Signal()
+        self.clock_domains.cd_sys = ClockDomain()
+
+        # # #
+
+        if use_ps7_clk:
+            assert sys_clk_freq == 100e6
+            self.comb += ClockSignal("sys").eq(ClockSignal("ps7"))
+            self.comb += ResetSignal("sys").eq(ResetSignal("ps7") | self.rst)
+        else:
+            self.submodules.pll = pll = S7PLL(speedgrade=-1)
+            self.comb += pll.reset.eq(self.rst)
+            pll.register_clkin(platform.request("clk33_333"), 33.333e6)
+            pll.create_clkout(self.cd_sys, sys_clk_freq)
+
+# BaseSoC ------------------------------------------------------------------------------------------
+
+class BaseSoC(SoCCore):
+    def __init__(self, sys_clk_freq=int(100e6), with_led_chaser=True, **kwargs):
+        platform = ebaz4205.Platform()
+
+        # SoCCore ----------------------------------------------------------------------------------
+        SoCCore.__init__(self, platform, sys_clk_freq,
+            ident          = "EBAZ4205 'Development' Board",
+            ident_version  = True,
+            **kwargs)
+
+        # Zynq7000 Integration ---------------------------------------------------------------------
+        if kwargs.get("cpu_type", None) == "zynq7000":
+            self.cpu.set_ps7_xci("xci/ebaz4205_ps7.xci")
+
+            # Connect AXI GP0 to the SoC with base address of 0x43c00000 (default one)
+            wb_gp0  = wishbone.Interface()
+            self.submodules += axi.AXI2Wishbone(
+                axi          = self.cpu.add_axi_gp_master(),
+                wishbone     = wb_gp0,
+                base_address = 0x43c00000)
+            self.add_wb_master(wb_gp0)
+
+        # CRG --------------------------------------------------------------------------------------
+        self.submodules.crg = _CRG(platform, sys_clk_freq)
+
+        # Leds -------------------------------------------------------------------------------------
+        if with_led_chaser:
+            self.submodules.leds = LedChaser(
+                pads         = platform.request_all("user_led"),
+                sys_clk_freq = sys_clk_freq)
+
+# Build --------------------------------------------------------------------------------------------
+
+def main():
+    parser = argparse.ArgumentParser(description="LiteX SoC on EBAZ4205")
+    parser.add_argument("--build",        action="store_true", help="Build bitstream")
+    parser.add_argument("--load",         action="store_true", help="Load bitstream")
+    parser.add_argument("--sys-clk-freq", default=100e6,       help="System clock frequency (default: 100MHz)")
+    builder_args(parser)
+    soc_core_args(parser)
+    vivado_build_args(parser)
+    args = parser.parse_args()
+
+    soc = BaseSoC(
+        sys_clk_freq = int(float(args.sys_clk_freq)),
+        **soc_core_argdict(args)
+    )
+    builder = Builder(soc, **builder_argdict(args))
+    builder.build(**vivado_build_argdict(args), run=args.build)
+
+    if args.load:
+        prog = soc.platform.create_programmer()
+        prog.load_bitstream(os.path.join(builder.gateware_dir, soc.build_name + ".bit"), device=1)
+
+if __name__ == "__main__":
+    main()