+++ /dev/null
-from nmigen import Signal, Module, Cat, Const, Elaboratable
-
-from TLB.ariane.ptw import TLBUpdate, PTE
-
-
-class TLBEntry:
- def __init__(self, asid_width):
- self.asid = Signal(asid_width,name="ent_asid")
- # SV48 defines four levels of page tables
- self.vpn0 = Signal(9,name="ent_vpn0")
- self.vpn1 = Signal(9,name="ent_vpn1")
- self.vpn2 = Signal(9,name="ent_vpn2")
- self.vpn3 = Signal(9,name="ent_vpn3")
- self.is_2M = Signal(name="ent_is_2M")
- self.is_1G = Signal(name="ent_is_1G")
- self.is_512G = Signal(name="ent_is_512G")
- self.valid = Signal(name="ent_valid")
-
- def flatten(self):
- return Cat(*self.ports())
-
- def eq(self, x):
- return self.flatten().eq(x.flatten())
-
- def ports(self):
- return [self.asid, self.vpn0, self.vpn1, self.vpn2,
- self.is_2M, self.is_1G, self.valid]
-
-
-class TLBContent(Elaboratable):
- def __init__(self, pte_width, asid_width):
- self.asid_width = asid_width
- self.pte_width = pte_width
- self.flush_i = Signal() # Flush signal
- # Update TLB
- self.update_i = TLBUpdate(asid_width)
- self.vpn3 = Signal(9)
- self.vpn2 = Signal(9)
- self.vpn1 = Signal(9)
- self.vpn0 = Signal(9)
- self.replace_en_i = Signal() # replace the following entry,
- # set by replacement strategy
- # Lookup signals
- self.lu_asid_i = Signal(asid_width)
- self.lu_content_o = Signal(pte_width)
- self.lu_is_512G_o = Signal()
- self.lu_is_2M_o = Signal()
- self.lu_is_1G_o = Signal()
- self.lu_hit_o = Signal()
-
- def elaborate(self, platform):
- m = Module()
-
- tags = TLBEntry(self.asid_width)
-
-
- content = Signal(self.pte_width)
-
- m.d.comb += [self.lu_hit_o.eq(0),
- self.lu_is_512G_o.eq(0),
- self.lu_is_2M_o.eq(0),
- self.lu_is_1G_o.eq(0)]
-
- # temporaries for lookup
- asid_ok = Signal(reset_less=True)
- # tags_ok = Signal(reset_less=True)
-
- vpn3_ok = Signal(reset_less=True)
- vpn2_ok = Signal(reset_less=True)
- vpn1_ok = Signal(reset_less=True)
- vpn0_ok = Signal(reset_less=True)
-
- #tags_2M = Signal(reset_less=True)
- vpn0_or_2M = Signal(reset_less=True)
-
- m.d.comb += [
- #compare asid and vpn*
- asid_ok.eq(tags.asid == self.lu_asid_i),
- vpn3_ok.eq(tags.vpn3 == self.vpn3),
- vpn2_ok.eq(tags.vpn2 == self.vpn2),
- vpn1_ok.eq(tags.vpn1 == self.vpn1),
- vpn0_ok.eq(tags.vpn0 == self.vpn0),
- vpn0_or_2M.eq(tags.is_2M | vpn0_ok)
- ]
-
-
- with m.If(asid_ok & tags.valid):
- # first level, only vpn3 needs to match
- with m.If (tags.is_512G & vpn3_ok):
- m.d.comb += [ self.lu_content_o.eq(content),
- self.lu_is_512G_o.eq(1),
- self.lu_hit_o.eq(1),
- ]
- # second level , second level vpn2 and vpn3 need to match
- with m.Elif (tags.is_1G & vpn2_ok & vpn3_ok):
- m.d.comb += [ self.lu_content_o.eq(content),
- self.lu_is_1G_o.eq(1),
- self.lu_hit_o.eq(1),
- ]
- # not a giga page hit nor a tera page hit so check further
- with m.Elif(vpn1_ok):
- # this could be a 2 mega page hit or a 4 kB hit
- # output accordingly
- with m.If(vpn0_or_2M):
- m.d.comb += [ self.lu_content_o.eq(content),
- self.lu_is_2M_o.eq(tags.is_2M),
- self.lu_hit_o.eq(1),
- ]
- # ------------------
- # Update or Flush
- # ------------------
-
- # temporaries
- replace_valid = Signal(reset_less=True)
- m.d.comb += replace_valid.eq(self.update_i.valid & self.replace_en_i)
-
- # flush
- with m.If (self.flush_i):
- # invalidate (flush) conditions: all if zero or just this ASID
- with m.If (self.lu_asid_i == Const(0, self.asid_width) |
- (self.lu_asid_i == tags.asid)):
- m.d.sync += tags.valid.eq(0)
-
- # normal replacement
- with m.Elif(replace_valid):
- m.d.sync += [ # update tag array
- tags.asid.eq(self.update_i.asid),
- tags.vpn3.eq(self.update_i.vpn[27:36]),
- tags.vpn2.eq(self.update_i.vpn[18:27]),
- tags.vpn1.eq(self.update_i.vpn[9:18]),
- tags.vpn0.eq(self.update_i.vpn[0:9]),
- tags.is_512G.eq(self.update_i.is_512G),
- tags.is_1G.eq(self.update_i.is_1G),
- tags.is_2M.eq(self.update_i.is_2M),
- tags.valid.eq(1),
- # and content as well
- content.eq(self.update_i.content.flatten())
- ]
- return m
-
- def ports(self):
- return [self.flush_i,
- self.lu_asid_i,
- self.lu_is_2M_o, self.lu_is_1G_o,self.lu_is_512G_o, self.lu_hit_o,
- ] + self.update_i.content.ports() + self.update_i.ports()
projects / soc.git / blobdiff