+++ /dev/null
-"""
-# Copyright 2018 ETH Zurich and University of Bologna.
-# Copyright and related rights are licensed under the Solderpad Hardware
-# License, Version 0.51 (the "License"); you may not use this file except in
-# compliance with the License. You may obtain a copy of the License at
-# http:#solderpad.org/licenses/SHL-0.51. Unless required by applicable law
-# or agreed to in writing, software, hardware and materials distributed under
-# this License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
-# CONDITIONS OF ANY KIND, either express or implied. See the License for the
-# specific language governing permissions and limitations under the License.
-#
-# Author: David Schaffenrath, TU Graz
-# Author: Florian Zaruba, ETH Zurich
-# Date: 21.4.2017
-# Description: Translation Lookaside Buffer, SV39
-# fully set-associative
-
-Implementation in c++:
-https://raw.githubusercontent.com/Tony-Hu/TreePLRU/master/TreePLRU.cpp
-
-Text description:
-https://people.cs.clemson.edu/~mark/464/p_lru.txt
-
-Online simulator:
-http://www.ntu.edu.sg/home/smitha/ParaCache/Paracache/vm.html
-"""
-from math import log2
-from nmigen import Signal, Module, Cat, Const, Array
-from nmigen.cli import verilog, rtlil
-from nmigen.lib.coding import Encoder
-
-from ptw import TLBUpdate, PTE, ASID_WIDTH
-from plru import PLRU
-from tlb_content import TLBContent
-
-TLB_ENTRIES = 8
-
-class TLB:
- def __init__(self, tlb_entries=8, asid_width=8):
- self.tlb_entries = tlb_entries
- self.asid_width = asid_width
-
- self.flush_i = Signal() # Flush signal
- # Lookup signals
- self.lu_access_i = Signal()
- self.lu_asid_i = Signal(self.asid_width)
- self.lu_vaddr_i = Signal(64)
- self.lu_content_o = PTE()
- self.lu_is_2M_o = Signal()
- self.lu_is_1G_o = Signal()
- self.lu_hit_o = Signal()
- # Update TLB
- self.pte_width = len(self.lu_content_o.flatten())
- self.update_i = TLBUpdate(asid_width)
-
- def elaborate(self, platform):
- m = Module()
-
- vpn2 = Signal(9)
- vpn1 = Signal(9)
- vpn0 = Signal(9)
-
- #-------------
- # Translation
- #-------------
-
- # SV39 defines three levels of page tables
- m.d.comb += [ vpn0.eq(self.lu_vaddr_i[12:21]),
- vpn1.eq(self.lu_vaddr_i[21:30]),
- vpn2.eq(self.lu_vaddr_i[30:39]),
- ]
-
- tc = []
- for i in range(self.tlb_entries):
- tlc = TLBContent(self.pte_width, self.asid_width)
- setattr(m.submodules, "tc%d" % i, tlc)
- tc.append(tlc)
- # connect inputs
- tlc.update_i = self.update_i # saves a lot of graphviz links
- m.d.comb += [tlc.vpn0.eq(vpn0),
- tlc.vpn1.eq(vpn1),
- tlc.vpn2.eq(vpn2),
- tlc.flush_i.eq(self.flush_i),
- #tlc.update_i.eq(self.update_i),
- tlc.lu_asid_i.eq(self.lu_asid_i)]
- tc = Array(tc)
-
- #--------------
- # Select hit
- #--------------
-
- # use Encoder to select hit index
- # XXX TODO: assert that there's only one valid entry (one lu_hit)
- hitsel = Encoder(self.tlb_entries)
- m.submodules.hitsel = hitsel
-
- hits = []
- for i in range(self.tlb_entries):
- hits.append(tc[i].lu_hit_o)
- m.d.comb += hitsel.i.eq(Cat(*hits)) # (goes into plru as well)
- idx = hitsel.o
-
- active = Signal(reset_less=True)
- m.d.comb += active.eq(~hitsel.n)
- with m.If(active):
- # active hit, send selected as output
- m.d.comb += [ self.lu_is_1G_o.eq(tc[idx].lu_is_1G_o),
- self.lu_is_2M_o.eq(tc[idx].lu_is_2M_o),
- self.lu_hit_o.eq(1),
- self.lu_content_o.flatten().eq(tc[idx].lu_content_o),
- ]
-
- #--------------
- # PLRU.
- #--------------
-
- p = PLRU(self.tlb_entries)
- plru_tree = Signal(p.TLBSZ)
- m.submodules.plru = p
-
- # connect PLRU inputs/outputs
- # XXX TODO: assert that there's only one valid entry (one replace_en)
- en = []
- for i in range(self.tlb_entries):
- en.append(tc[i].replace_en_i)
- m.d.comb += [Cat(*en).eq(p.replace_en_o), # output from PLRU into tags
- p.lu_hit.eq(hitsel.i),
- p.lu_access_i.eq(self.lu_access_i),
- p.plru_tree.eq(plru_tree)]
- m.d.sync += plru_tree.eq(p.plru_tree_o)
-
- #--------------
- # Sanity checks
- #--------------
-
- assert (self.tlb_entries % 2 == 0) and (self.tlb_entries > 1), \
- "TLB size must be a multiple of 2 and greater than 1"
- assert (self.asid_width >= 1), \
- "ASID width must be at least 1"
-
- return m
-
- """
- # Just for checking
- function int countSetBits(logic[self.tlb_entries-1:0] vector);
- automatic int count = 0;
- foreach (vector[idx]) begin
- count += vector[idx];
- end
- return count;
- endfunction
-
- assert property (@(posedge clk_i)(countSetBits(lu_hit) <= 1))
- else $error("More then one hit in TLB!"); $stop(); end
- assert property (@(posedge clk_i)(countSetBits(replace_en) <= 1))
- else $error("More then one TLB entry selected for next replace!");
- """
-
- def ports(self):
- return [self.flush_i, self.lu_access_i,
- self.lu_asid_i, self.lu_vaddr_i,
- self.lu_is_2M_o, self.lu_is_1G_o, self.lu_hit_o,
- ] + self.lu_content_o.ports() + self.update_i.ports()
-
-if __name__ == '__main__':
- tlb = TLB()
- vl = rtlil.convert(tlb, ports=tlb.ports())
- with open("test_tlb.il", "w") as f:
- f.write(vl)
-
projects / soc.git / blobdiff