gram/phy/dfi.py

   1 # This file is Copyright (c) 2015 Sebastien Bourdeauducq <sb@m-labs.hk>
   2 # This file is Copyright (c) 2020 LambdaConcept <contact@lambdaconcept.com>
   3
   4 from nmigen import *
   5 from nmigen.hdl.rec import *
   6
   7 __ALL__ = ["Interface"]
   8
   9
  10 def phase_description(addressbits, bankbits, nranks, databits):
  11     return [
  12         # cmd description
  13         ("address", addressbits, DIR_FANOUT),
  14         ("bank", bankbits, DIR_FANOUT),
  15         ("cas", 1, DIR_FANOUT),
  16         ("cs_n", nranks, DIR_FANOUT),
  17         ("ras", 1, DIR_FANOUT),
  18         ("we", 1, DIR_FANOUT),
  19         ("clk_en", nranks, DIR_FANOUT),
  20         ("odt", nranks, DIR_FANOUT),
  21         ("reset_n", 1, DIR_FANOUT),
  22         ("act", 1, DIR_FANOUT),
  23         # wrdata description
  24         ("wrdata", databits, DIR_FANOUT),
  25         ("wrdata_en", 1, DIR_FANOUT),
  26         ("wrdata_mask", databits//8, DIR_FANOUT),
  27         # rddata description
  28         ("rddata_en", 1, DIR_FANOUT),
  29         ("rddata", databits, DIR_FANIN),
  30         ("rddata_valid", 1, DIR_FANIN),
  31     ]
  32
  33
  34 class Interface:
  35     def __init__(self, addressbits, bankbits, nranks, databits, nphases=1,
  36                        name=None):
  37         print ("DFI Interface", name, "addr", addressbits,
  38                 "bankbits", bankbits, "nranks", nranks, "data", databits,
  39                 "phases", nphases)
  40         self.phases = []
  41         for p in range(nphases):
  42             p = Record(phase_description(addressbits, bankbits,
  43                                          nranks, databits),
  44                        name=name)
  45             self.phases += [p]
  46             # set all logic-inverted x_n signal resets to on at power-up
  47             p.cas.reset = 1
  48             p.cs_n.reset = -1
  49             p.we.reset = 1
  50             p.act.reset = 1
  51
  52     def connect(self, target):
  53         if not isinstance(target, Interface):
  54             raise TypeError("Target must be an instance of Interface, not {!r}"
  55                             .format(target))
  56
  57         ret = []
  58         for i in range(min(len(self.phases), len(target.phases))):
  59             ret += [self.phases[i].connect(target.phases[i])]
  60
  61         return ret