src/soc/experiment/pi2ls.py

   1 """PortInterface to LoadStoreUnitInterface adapter
   2
   3     PortInterface   LoadStoreUnitInterface
   4     -------------   ----------------------
   5
   6     is_ld_i/1       x_ld_i
   7     is_st_i/1       x_st_i
   8
   9     data_len/4      x_mask/16  (translate using LenExpand)
  10
  11     busy_o/1        most likely to be x_busy_o
  12     go_die_i/1      rst?
  13     addr.data/48    x_addr_i (x_addr_i[:4] goes into LenExpand)
  14     addr.ok/1       probably x_valid_i & ~x_stall_i
  15
  16     addr_ok_o/1     no equivalent.  *might* work using x_stall_i
  17     addr_exc_o/2(?) m_load_err_o and m_store_err_o
  18
  19     ld.data/64      m_ld_data_o
  20     ld.ok/1         probably implicit, when x_busy drops low
  21     st.data/64      x_st_data_i
  22     st.ok/1         probably kinda redundant, set to x_st_i
  23 """
  24
  25 from soc.minerva.units.loadstore import LoadStoreUnitInterface
  26 from soc.experiment.pimem import PortInterface
  27 from soc.scoreboard.addr_match import LenExpand
  28
  29 from nmigen import Elaboratable, Module, Signal
  30
  31
  32 class Pi2LSUI(Elaboratable):
  33
  34     def __init__(self, name, pi=None, lsui=None, regwid=64, addrwid=48):
  35         self.addrbits = 4
  36         if pi is None:
  37             pi = PortInterface(name="%s_pi", regwid=regwid, addrwid=addrwid)
  38         self.pi = pi
  39         if lsui is None:
  40             lsui = LoadStoreUnitInterface(addrwid, self.addrbits, regwid)
  41         self.lsui = lsui
  42
  43     def splitaddr(self, addr):
  44         """split the address into top and bottom bits of the memory granularity
  45         """
  46         return addr[:self.addrbits], addr[self.addrbits:]
  47
  48     def elaborate(self, platform):
  49         m = Module()
  50         pi, lsui, addrbits = self.pi, self.lsui, self.addrbits
  51         m.submodules.lenexp = lenexp = LenExpand(self.addrbits, 8)
  52
  53         m.d.comb += lsui.x_ld_i.eq(pi.is_ld_i)
  54         m.d.comb += lsui.x_st_i.eq(pi.is_st_i)
  55
  56         with m.If(pi.addr.ok):
  57             # expand the LSBs of address plus LD/ST len into 16-bit mask
  58             m.d.comb += lenexp.len_i.eq(pi.data_len)
  59             m.d.comb += lenexp.addr_i.eq(pi.addr.data[addrbits]) # LSBs of addr
  60             m.d.comb += lsui.x_mask_i.eq(lenexp.lexp_o)
  61             # pass through the address, indicate "valid"
  62             m.d.comb += lsui.x_addr_i.eq(pi.addr.data) # full address
  63             m.d.comb += lsui.x_valid_i.eq(1)
  64
  65         with m.If(pi.is_ld_i):
  66             m.d.comb += pi.ld.data.eq(lsui.m_ld_data_o)
  67             #m.d.comb += pi.ld.ok.eq(TODO)
  68
  69         with m.If(pi.is_st_i & pi.st.ok):
  70             m.d.comb += lsui.x_st_data_i.eq(pi.st.data)
  71
  72         return m
  73