src/crg.py

   1 # Copyright (c) 2020 LambdaConcept <contact@lambdaconcept.com>
   2 # Copyright (c) 2021 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
   3 # Copyright (c) 2018-2020 Florent Kermarrec <florent@enjoy-digital.fr>
   4 # Copyright (c) 2019 Michael Betz <michibetz@gmail.com>
   5 #
   6 # Based on code from LambaConcept, from the gram example which is BSD-2-License
   7 # https://github.com/jeanthom/gram/tree/master/examples
   8 #
   9 # Modifications for the Libre-SOC Project funded by NLnet and NGI POINTER
  10 # under EU Grants 871528 and 957073, under the LGPLv3+ License
  11
  12
  13 from nmigen import (Elaboratable, Module, Signal, ClockDomain, Instance,
  14                     ClockSignal, ResetSignal)
  15
  16 __ALL__ = ["ECPIX5CRG"]
  17
  18 class PLL(Elaboratable):
  19     nclkouts_max    = 3
  20     clki_div_range  = (1, 128+1)
  21     clkfb_div_range = (1, 128+1)
  22     clko_div_range  = (1, 128+1)
  23     clki_freq_range = (    8e6,  400e6)
  24     clko_freq_range = (3.125e6,  400e6)
  25     vco_freq_range  = (  400e6,  800e6)
  26
  27     def __init__(self, clkin,
  28                        clksel=Signal(shape=2, reset=2),
  29                        reset=Signal(reset_less=True),
  30                        locked=Signal()):
  31         self.clkin = clkin
  32         self.clkin_freq = None
  33         self.clksel = clksel
  34         self.locked = locked
  35         self.reset  = reset
  36         self.nclkouts   = 0
  37         self.clkouts    = {}
  38         self.config     = {}
  39         self.params     = {}
  40
  41     def ports(self):
  42         return [
  43             self.clkin,
  44             self.clksel,
  45             self.lock,
  46         ] + list(self.clkouts.values())
  47
  48     def set_clkin_freq(self, freq):
  49         (clki_freq_min, clki_freq_max) = self.clki_freq_range
  50         assert freq >= clki_freq_min
  51         assert freq <= clki_freq_max
  52         self.clkin_freq = freq
  53
  54     def create_clkout(self, cd, freq, phase=0, margin=1e-2):
  55         (clko_freq_min, clko_freq_max) = self.clko_freq_range
  56         assert freq >= clko_freq_min
  57         assert freq <= clko_freq_max
  58         assert self.nclkouts < self.nclkouts_max
  59         self.clkouts[self.nclkouts] = (cd, freq, phase, margin)
  60         #create_clkout_log(self.logger, cd.name, freq, margin, self.nclkouts)
  61         self.nclkouts += 1
  62
  63     def compute_config(self):
  64         config = {}
  65         for clki_div in range(*self.clki_div_range):
  66             config["clki_div"] = clki_div
  67             for clkfb_div in range(*self.clkfb_div_range):
  68                 all_valid = True
  69                 vco_freq = self.clkin_freq/clki_div*clkfb_div*1 # clkos3_div=1
  70                 (vco_freq_min, vco_freq_max) = self.vco_freq_range
  71                 if vco_freq >= vco_freq_min and vco_freq <= vco_freq_max:
  72                     for n, (clk, f, p, m) in sorted(self.clkouts.items()):
  73                         valid = False
  74                         for d in range(*self.clko_div_range):
  75                             clk_freq = vco_freq/d
  76                             if abs(clk_freq - f) <= f*m:
  77                                 config["clko{}_freq".format(n)]  = clk_freq
  78                                 config["clko{}_div".format(n)]   = d
  79                                 config["clko{}_phase".format(n)] = p
  80                                 valid = True
  81                                 break
  82                         if not valid:
  83                             all_valid = False
  84                 else:
  85                     all_valid = False
  86                 if all_valid:
  87                     config["vco"] = vco_freq
  88                     config["clkfb_div"] = clkfb_div
  89                     #compute_config_log(self.logger, config)
  90                     return config
  91         raise ValueError("No PLL config found")
  92
  93     def elaborate(self, platform):
  94         config = self.compute_config()
  95         clkfb = Signal()
  96         self.params.update(
  97             # attributes
  98             a_FREQUENCY_PIN_CLKI     = str(self.clkin_freq/1e6),
  99             a_ICP_CURRENT            = "6",
 100             a_LPF_RESISTOR           = "16",
 101             a_MFG_ENABLE_FILTEROPAMP = "1",
 102             a_MFG_GMCREF_SEL         = "2",
 103             # parameters
 104             p_FEEDBK_PATH   = "INT_OS3", # CLKOS3 rsvd for feedback with div=1.
 105             p_CLKOS3_ENABLE = "ENABLED",
 106             p_CLKOS3_DIV    = 1,
 107             p_CLKFB_DIV     = config["clkfb_div"],
 108             p_CLKI_DIV      = config["clki_div"],
 109             # reset, input clock, lock-achieved output
 110             i_RST           = self.reset,
 111             i_CLKI          = self.clkin,
 112             o_LOCK          = self.locked,
 113         )
 114         # for each clock-out, set additional parameters
 115         for n, (clk, f, p, m) in sorted(self.clkouts.items()):
 116             n_to_l = {0: "P", 1: "S", 2: "S2"}
 117             div    = config["clko{}_div".format(n)]
 118             cphase = int(p*(div + 1)/360 + div)
 119             self.params["p_CLKO{}_ENABLE".format(n_to_l[n])] = "ENABLED"
 120             self.params["p_CLKO{}_DIV".format(n_to_l[n])]    = div
 121             self.params["p_CLKO{}_FPHASE".format(n_to_l[n])] = 0
 122             self.params["p_CLKO{}_CPHASE".format(n_to_l[n])] = cphase
 123             self.params["o_CLKO{}".format(n_to_l[n])]        = clk
 124
 125         m = Module()
 126         pll = Instance("EHXPLLL", **self.params)
 127         m.submodules.pll = pll
 128         return m
 129
 130         pll = Instance("EHXPLLL",
 131                        p_OUTDIVIDER_MUXA='DIVA',
 132                        p_OUTDIVIDER_MUXB='DIVB',
 133                        p_CLKOP_ENABLE='ENABLED',
 134                        p_CLKOS_ENABLE='ENABLED',
 135                        p_CLKOS2_ENABLE='DISABLED',
 136                        p_CLKOS3_ENABLE='DISABLED',
 137                        p_CLKOP_DIV=self.CLKOP_DIV,
 138                        p_CLKOS_DIV=self.CLKOS_DIV,
 139                        p_CLKFB_DIV=self.CLKFB_DIV,
 140                        p_CLKI_DIV=self.CLKI_DIV,
 141                        p_FEEDBK_PATH='INT_OP',
 142                        p_CLKOP_TRIM_POL="FALLING",
 143                        p_CLKOP_TRIM_DELAY=0,
 144                        p_CLKOS_TRIM_POL="FALLING",
 145                        p_CLKOS_TRIM_DELAY=0,
 146                        i_CLKI=self.clkin,
 147                        i_RST=0,
 148                        i_STDBY=0,
 149                        i_PHASESEL0=0,
 150                        i_PHASESEL1=0,
 151                        i_PHASEDIR=0,
 152                        i_PHASESTEP=0,
 153                        i_PHASELOADREG=0,
 154                        i_PLLWAKESYNC=0,
 155                        i_ENCLKOP=1,
 156                        i_ENCLKOS=1,
 157                        i_ENCLKOS2=0,
 158                        i_ENCLKOS3=0,
 159                        o_CLKOP=self.clkout1,
 160                        o_CLKOS=self.clkout2,
 161                        o_CLKOS2=self.clkout3,
 162                        o_CLKOS3=self.clkout4,
 163                        o_LOCK=self.lock,
 164                        )
 165
 166
 167 class ECPIX5CRG(Elaboratable):
 168     def __init__(self, sys_clk_freq=100e6):
 169         self.sys_clk_freq = sys_clk_freq
 170
 171     def elaborate(self, platform):
 172         m = Module()
 173
 174         # Get 100Mhz from oscillator
 175         clk100 = platform.request("clk100")
 176         cd_rawclk = ClockDomain("rawclk", local=True, reset_less=True)
 177         m.d.comb += cd_rawclk.clk.eq(clk100)
 178         m.domains += cd_rawclk
 179
 180         # Reset
 181         reset = platform.request(platform.default_rst).i
 182         gsr0 = Signal()
 183         gsr1 = Signal()
 184
 185         m.submodules += [
 186             Instance("FD1S3AX", p_GSR="DISABLED",
 187                                 i_CK=ClockSignal("rawclk"),
 188                                 i_D=~reset,
 189                                 o_Q=gsr0),
 190             Instance("FD1S3AX", p_GSR="DISABLED",
 191                                 i_CK=ClockSignal("rawclk"),
 192                                 i_D=gsr0,
 193                                 o_Q=gsr1),
 194             Instance("SGSR", i_CLK=ClockSignal("rawclk"),
 195                              i_GSR=gsr1),
 196         ]
 197
 198         # Power-on delay (655us)
 199         podcnt = Signal(16, reset=2**16-1)
 200         pod_done = Signal()
 201         with m.If(podcnt != 0):
 202             m.d.rawclk += podcnt.eq(podcnt-1)
 203         m.d.rawclk += pod_done.eq(podcnt == 0)
 204
 205         # Generating sync2x (200Mhz) and init (25Mhz) from clk100
 206         cd_sync2x = ClockDomain("sync2x", local=False)
 207         cd_sync2x_unbuf = ClockDomain("sync2x_unbuf",
 208                                       local=False, reset_less=True)
 209         cd_init = ClockDomain("init", local=False)
 210         cd_sync = ClockDomain("sync", local=False)
 211         cd_dramsync = ClockDomain("dramsync", local=False)
 212         m.submodules.pll = pll = PLL(ClockSignal("rawclk"), reset=reset)
 213         pll.set_clkin_freq(100e6)
 214         pll.create_clkout(ClockSignal("sync2x_unbuf"), 2*self.sys_clk_freq)
 215         pll.create_clkout(ClockSignal("init"), 25e6)
 216         m.submodules += Instance("ECLKSYNCB",
 217                 i_ECLKI = ClockSignal("sync2x_unbuf"),
 218                 i_STOP  = 0,
 219                 o_ECLKO = ClockSignal("sync2x"))
 220         m.domains += cd_sync2x_unbuf
 221         m.domains += cd_sync2x
 222         m.domains += cd_init
 223         m.domains += cd_sync
 224         m.domains += cd_dramsync
 225         reset_ok = Signal(reset_less=True)
 226         m.d.comb += reset_ok.eq(~pll.locked|~pod_done)
 227         m.d.comb += ResetSignal("init").eq(reset_ok)
 228         m.d.comb += ResetSignal("sync").eq(reset_ok)
 229         m.d.comb += ResetSignal("dramsync").eq(reset_ok)
 230
 231         # # Generating sync (100Mhz) from sync2x
 232
 233         m.submodules += Instance("CLKDIVF",
 234             p_DIV="2.0",
 235             i_ALIGNWD=0,
 236             i_CLKI=ClockSignal("sync2x"),
 237             i_RST=0,
 238             o_CDIVX=ClockSignal("sync"))
 239         m.d.comb += ClockSignal("dramsync").eq(ClockSignal("sync"))
 240
 241         return m