32 lines
891 B
Python
32 lines
891 B
Python
from migen.fhdl.structure import *
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from migen.bus import wishbone
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from migen.corelogic.misc import timeline
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class NorFlash:
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def __init__(self, adr_width, rd_timing):
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self.adr_width = adr_width
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self.rd_timing = rd_timing
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self.bus = wishbone.Interface()
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self.adr = Signal(BV(adr_width-1))
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self.d = Signal(BV(16))
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self.oe_n = Signal()
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self.we_n = Signal()
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self.ce_n = Signal()
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def get_fragment(self):
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comb = [self.oe_n.eq(0), self.we_n.eq(1),
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self.ce_n.eq(0)]
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sync = timeline(self.bus.cyc & self.bus.stb, [
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(0, [self.adr.eq(Cat(0, self.bus.adr[:self.adr_width-2]))]),
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(self.rd_timing, [
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self.bus.dat_r[16:].eq(self.d),
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self.adr.eq(Cat(1, self.bus.adr[:self.adr_width-2]))]),
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(2*self.rd_timing, [
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self.bus.dat_r[:16].eq(self.d),
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self.bus.ack.eq(1)]),
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(2*self.rd_timing + 1, [
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self.bus.ack.eq(0)])
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])
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return Fragment(comb, sync)
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