src/soc/bus/uart_16550.py

   1 #!/usr/bin/env python3
   2 #
   3 # SPDX-License-Identifier: LGPLv3+
   4 # Copyright (C) 2022 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
   5 # Sponsored by NLnet and NGI POINTER under EU Grants 871528 and 957073
   6 # Part of the Libre-SOC Project.
   7 #
   8 # this is a wrapper around the opencores verilog uart16550 module
   9
  10 from nmigen import (Elaboratable, Cat, Module, Signal, ClockSignal, Instance,
  11                     ResetSignal)
  12
  13 from nmigen_soc.wishbone.bus import Interface
  14 from nmigen.cli import rtlil, verilog
  15 import os
  16
  17 __all__ = ["UART16550"]
  18
  19
  20 class UART16550(Elaboratable):
  21     """16550 UART from opencores, nmigen wrapper.  remember to call
  22        UART16550.add_verilog_source
  23     """
  24
  25     def __init__(self, bus=None, features=None, name=None, data_width=32,
  26                        pins=None):
  27         if name is not None:
  28             # convention: give the name in the format "name_number"
  29             self.idx = int(name.split("_")[-1])
  30         else:
  31             self.idx = 0
  32             name = "uart_0"
  33         self.data_width = data_width
  34
  35         # set up the wishbone bus
  36         if features is None:
  37             features = frozenset()
  38         if bus is None:
  39             bus = Interface(addr_width=5,
  40                             data_width=data_width,
  41                             features=features,
  42                             granularity=8,
  43                             name=name+"_wb_%d" % self.idx)
  44         self.bus = bus
  45         assert len(self.bus.dat_r) == data_width, \
  46                         "bus width must be %d" % data_width
  47
  48         # IRQ for data buffer receive/xmit
  49         self.irq = Signal()
  50
  51         # 9-pin UART signals (if anyone still remembers those...)
  52         self.tx_o = Signal() # transmit
  53         self.rx_i = Signal() # receive
  54         self.rts_o = Signal() # ready to send
  55         self.cts_i = Signal() # clear to send
  56         self.dtr_o = Signal() # data terminal ready
  57         self.dsr_i = Signal() # data send ready
  58         self.ri_i = Signal() # can't even remember what this is!
  59         self.dcd_i = Signal() # or this!
  60
  61         # pins resource
  62         self.pins = pins
  63
  64     @classmethod
  65     def add_verilog_source(cls, verilog_src_dir, platform):
  66         # add each of the verilog sources, needed for when doing platform.build
  67         for fname in ['raminfr.v', 'uart_defines.v', 'uart_rfifo.v',
  68                       'uart_top.v', 'timescale.v', 'uart_receiver.v',
  69                       'uart_sync_flops.v', 'uart_transmitter.v',
  70                       'uart_debug_if.v', 'uart_regs.v',
  71                       'uart_tfifo.v', 'uart_wb.v'
  72                      ]:
  73             # prepend the src directory to each filename, add its contents
  74             fullname = os.path.join(verilog_src_dir, fname)
  75             with open(fullname) as f:
  76                 platform.add_file(fullname, f)
  77
  78     def elaborate(self, platform):
  79         m = Module()
  80         comb = m.d.comb
  81
  82         # create definition of external verilog 16550 uart here, so that                # nmigen understands I/O directions (defined by i_ and o_ prefixes)
  83         idx, bus = self.idx, self.bus
  84         uart = Instance("uart_top",
  85                             # clock/reset (use DomainRenamer if needed)
  86                             i_wb_clk_i=ClockSignal(),
  87                             i_wb_rst_i=ResetSignal(),
  88                             # wishbone bus signals
  89                             i_wb_adr_i=bus.adr,
  90                             i_wb_dat_i=bus.dat_w,
  91                             i_wb_sel_i=bus.sel,
  92                             o_wb_dat_o=bus.dat_r,
  93                             i_wb_we_i=bus.we,
  94                             i_wb_stb_i=bus.stb,
  95                             i_wb_cyc_i=bus.cyc,
  96                             o_wb_ack_o=bus.ack,
  97                             # interrupt line
  98                             o_int_o=self.irq,
  99                             # 9-pin RS232/UART signals
 100                             o_stx_pad_o=self.tx_o,
 101                             i_srx_pad_i=self.rx_i,
 102                             o_rts_pad_o=self.rts_o,
 103                             i_cts_pad_i=self.cts_i,
 104                             o_dtr_pad_o=self.dtr_o,
 105                             i_dsr_pad_i=self.dsr_i,
 106                             i_ri_pad_i=self.ri_i,
 107                             i_dcd_pad_i=self.dcd_i
 108                             );
 109
 110         m.submodules['uart16550_%d' % self.idx] = uart
 111
 112         if self.pins is not None:
 113             comb += self.pins.tx.eq(self.tx_o)
 114             comb += self.rx_i.eq(self.pins.rx)
 115
 116         return m
 117
 118
 119 def create_ilang(dut, ports, test_name):
 120     vl = rtlil.convert(dut, name=test_name, ports=ports)
 121     with open("%s.il" % test_name, "w") as f:
 122         f.write(vl)
 123
 124 def create_verilog(dut, ports, test_name):
 125     vl = verilog.convert(dut, name=test_name, ports=ports)
 126     with open("%s.v" % test_name, "w") as f:
 127         f.write(vl)
 128
 129
 130 if __name__ == "__main__":
 131     uart = UART16550(name="uart_0", data_width=8)
 132     create_ilang(uart, [uart.bus.cyc, uart.bus.stb, uart.bus.ack,
 133                         uart.bus.dat_r, uart.bus.dat_w, uart.bus.adr,
 134                         uart.bus.we, uart.bus.sel,
 135                         uart.irq,
 136                         uart.tx_o, uart.rx_i, uart.rts_o, uart.cts_i,
 137                         uart.dtr_o, uart.dsr_i, uart.ri_i, uart.dcd_i
 138                        ], "uart_0")
 139