litex/milkymist/m1crg/__init__.py

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from fractions import Fraction
from migen.fhdl.structure import *
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from migen.fhdl.specials import Instance
from migen.fhdl.module import Module
from migen.bank.description import *
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class M1CRG(Module, AutoCSR):
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def __init__(self, pads, outfreq1x):
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self.clock_domains.cd_sys = ClockDomain()
self.clock_domains.cd_sys2x_270 = ClockDomain()
self.clock_domains.cd_sys4x_wr = ClockDomain()
self.clock_domains.cd_sys4x_rd = ClockDomain()
self.clock_domains.cd_eth_rx = ClockDomain()
self.clock_domains.cd_eth_tx = ClockDomain()
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self.clock_domains.cd_vga = ClockDomain(reset_less=True)
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self.clk4x_wr_strb = Signal()
self.clk4x_rd_strb = Signal()
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self._r_cmd_data = CSRStorage(10)
self._r_send_cmd_data = CSR()
self._r_send_go = CSR()
self._r_status = CSRStatus(3)
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###
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infreq = 50*1000000
ratio = Fraction(outfreq1x)/Fraction(infreq)
in_period = float(Fraction(1000000000)/Fraction(infreq))
vga_progdata = Signal()
vga_progen = Signal()
vga_progdone = Signal()
vga_locked = Signal()
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self.specials += Instance("m1crg",
Instance.Parameter("in_period", in_period),
Instance.Parameter("f_mult", ratio.numerator),
Instance.Parameter("f_div", ratio.denominator),
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Instance.Input("clk50_pad", pads.clk50),
Instance.Input("trigger_reset", pads.trigger_reset),
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Instance.Input("eth_rx_clk_pad", pads.eth_rx_clk),
Instance.Input("eth_tx_clk_pad", pads.eth_tx_clk),
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Instance.Output("sys_clk", self.cd_sys.clk),
Instance.Output("sys_rst", self.cd_sys.rst),
Instance.Output("clk2x_270", self.cd_sys2x_270.clk),
Instance.Output("clk4x_wr", self.cd_sys4x_wr.clk),
Instance.Output("clk4x_rd", self.cd_sys4x_rd.clk),
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Instance.Output("eth_rx_clk", self.cd_eth_rx.clk),
Instance.Output("eth_tx_clk", self.cd_eth_tx.clk),
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Instance.Output("vga_clk", self.cd_vga.clk),
Instance.Output("clk4x_wr_strb", self.clk4x_wr_strb),
Instance.Output("clk4x_rd_strb", self.clk4x_rd_strb),
Instance.Output("norflash_rst_n", pads.norflash_rst_n),
Instance.Output("ddr_clk_pad_p", pads.ddr_clk_p),
Instance.Output("ddr_clk_pad_n", pads.ddr_clk_n),
Instance.Output("eth_phy_clk_pad", pads.eth_phy_clk),
Instance.Output("vga_clk_pad", pads.vga_clk),
Instance.Input("vga_progclk", ClockSignal()),
Instance.Input("vga_progdata", vga_progdata),
Instance.Input("vga_progen", vga_progen),
Instance.Output("vga_progdone", vga_progdone),
Instance.Output("vga_locked", vga_locked))
remaining_bits = Signal(max=11)
transmitting = Signal()
self.comb += transmitting.eq(remaining_bits != 0)
sr = Signal(10)
self.sync += [
If(self._r_send_cmd_data.re,
remaining_bits.eq(10),
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sr.eq(self._r_cmd_data.storage)
).Elif(transmitting,
remaining_bits.eq(remaining_bits - 1),
sr.eq(sr[1:])
)
]
self.comb += [
vga_progdata.eq(transmitting & sr[0]),
vga_progen.eq(transmitting | self._r_send_go.re)
]
# enforce gap between commands
busy_counter = Signal(max=14)
busy = Signal()
self.comb += busy.eq(busy_counter != 0)
self.sync += If(self._r_send_cmd_data.re,
busy_counter.eq(13)
).Elif(busy,
busy_counter.eq(busy_counter - 1)
)
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self.comb += self._r_status.status.eq(Cat(busy, vga_progdone, vga_locked))