71 lines
2.8 KiB
Python
71 lines
2.8 KiB
Python
from migen import *
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from migen.genlib.fifo import *
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import litex
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from litex.soc.interconnect import wishbone
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from migen.genlib.cdc import BusSynchronizer
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class NuBus2Wishbone(Module):
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def __init__(self, nubus, wb):
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# memory
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# nubus.mem_valid
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# nubus.mem_addr
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# nubus.mem_wdata
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# nubus.mem_write
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# nubus.mem_ready
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# nubus.mem_rdata
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#nubus.mem_error
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#nubus.mem_tryagain
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assert(len(wb.dat_r) == 32)
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assert(len(nubus.mem_wdata) == 32)
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assert(len(nubus.mem_write) == 4)
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#wb_dat_r_rev = Signal(32)
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#self.comb += [ wb_dat_r_rev[ 0: 8].eq(wb.dat_r[24:32]),
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# wb_dat_r_rev[ 8:16].eq(wb.dat_r[16:24]),
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# wb_dat_r_rev[16:24].eq(wb.dat_r[ 8:16]),
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# wb_dat_r_rev[24:32].eq(wb.dat_r[ 0: 8]), ]
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#nubus_mem_wdata_rev = Signal(32)
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#self.comb += [ nubus_mem_wdata_rev[ 0: 8].eq(nubus.mem_wdata[24:32]),
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# nubus_mem_wdata_rev[ 8:16].eq(nubus.mem_wdata[16:24]),
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# nubus_mem_wdata_rev[16:24].eq(nubus.mem_wdata[ 8:16]),
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# nubus_mem_wdata_rev[24:32].eq(nubus.mem_wdata[ 0: 8]), ]
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#nubus_mem_write_rev = Signal(4)
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#self.comb += [ nubus_mem_write_rev[0].eq(nubus.mem_write[3]),
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# nubus_mem_write_rev[1].eq(nubus.mem_write[2]),
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# nubus_mem_write_rev[2].eq(nubus.mem_write[1]),
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# nubus_mem_write_rev[3].eq(nubus.mem_write[0]), ]
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self.comb += wb.cyc.eq(nubus.mem_valid)
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self.comb += wb.stb.eq(nubus.mem_valid)
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self.comb += wb.we.eq(nubus.mem_write != 0)
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self.comb += [
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If(~nubus.mem_addr[23], # first 8 MiB of slot space: remap to last 8 Mib of SDRAM
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wb.adr.eq(Cat(nubus.mem_addr[2:23], Signal(1, reset=1), Signal(8, reset = 0x8f))), # 0x8f8...
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).Else( # second 8 MiB: direct access
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wb.adr.eq(Cat(nubus.mem_addr[2:24], Signal(8, reset = 0xf0)))), # 24 bits, a.k.a 22 bits of words
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]
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self.comb += If(nubus.mem_write == 0,
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wb.sel.eq(0xF)).Else(
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wb.sel.eq(nubus.mem_write))
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self.comb += [
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wb.dat_w.eq(nubus.mem_wdata),
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nubus.mem_rdata.eq(wb.dat_r),
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]
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#self.comb += If(nubus.mem_write == 0,
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# wb.sel.eq(0xF)).Else(
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# wb.sel.eq(nubus_mem_write_rev))
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#self.comb += [
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# wb.dat_w.eq(nubus_mem_wdata_rev),
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# nubus.mem_rdata.eq(wb_dat_r_rev),
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#]
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self.comb += nubus.mem_ready.eq(wb.ack)
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self.comb += nubus.mem_error.eq(0) # FIXME: TODO: ???
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self.comb += nubus.mem_tryagain.eq(0) # FIXME: TODO: ???
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