1 from nmigen
import Signal
, Module
, Cat
, Const
, Elaboratable
3 from TLB
.ariane
.ptw
import TLBUpdate
, PTE
7 def __init__(self
, asid_width
):
8 self
.asid
= Signal(asid_width
)
9 # SV48 defines four levels of page tables
14 #TODO_PLATEN: use that signal
20 return Cat(*self
.ports())
23 return self
.flatten().eq(x
.flatten())
26 return [self
.asid
, self
.vpn0
, self
.vpn1
, self
.vpn2
,
27 self
.is_2M
, self
.is_1G
, self
.valid
]
29 class TLBContent(Elaboratable
):
30 def __init__(self
, pte_width
, asid_width
):
31 self
.asid_width
= asid_width
32 self
.pte_width
= pte_width
33 self
.flush_i
= Signal() # Flush signal
35 self
.update_i
= TLBUpdate(asid_width
)
39 self
.replace_en_i
= Signal() # replace the following entry,
40 # set by replacement strategy
42 self
.lu_asid_i
= Signal(asid_width
)
43 self
.lu_content_o
= Signal(pte_width
)
44 self
.lu_is_2M_o
= Signal()
45 self
.lu_is_1G_o
= Signal()
46 self
.lu_hit_o
= Signal()
48 def elaborate(self
, platform
):
51 tags
= TLBEntry(self
.asid_width
)
52 content
= Signal(self
.pte_width
)
54 m
.d
.comb
+= [self
.lu_hit_o
.eq(0),
55 self
.lu_is_2M_o
.eq(0),
56 self
.lu_is_1G_o
.eq(0)]
58 # temporaries for 1st level match
59 asid_ok
= Signal(reset_less
=True)
60 vpn2_ok
= Signal(reset_less
=True)
61 tags_ok
= Signal(reset_less
=True)
62 vpn2_hit
= Signal(reset_less
=True)
63 m
.d
.comb
+= [tags_ok
.eq(tags
.valid
),
64 asid_ok
.eq(tags
.asid
== self
.lu_asid_i
),
65 vpn2_ok
.eq(tags
.vpn2
== self
.vpn2
),
66 vpn2_hit
.eq(tags_ok
& asid_ok
& vpn2_ok
)]
67 # temporaries for 2nd level match
68 vpn1_ok
= Signal(reset_less
=True)
69 tags_2M
= Signal(reset_less
=True)
70 vpn0_ok
= Signal(reset_less
=True)
71 vpn0_or_2M
= Signal(reset_less
=True)
72 m
.d
.comb
+= [vpn1_ok
.eq(self
.vpn1
== tags
.vpn1
),
73 tags_2M
.eq(tags
.is_2M
),
74 vpn0_ok
.eq(self
.vpn0
== tags
.vpn0
),
75 vpn0_or_2M
.eq(tags_2M | vpn0_ok
)]
76 # first level match, this may be a giga page,
77 # check the ASID flags as well
80 with m
.If (tags
.is_1G
):
81 m
.d
.comb
+= [ self
.lu_content_o
.eq(content
),
82 self
.lu_is_1G_o
.eq(1),
85 # not a giga page hit so check further
87 # this could be a 2 mega page hit or a 4 kB hit
89 with m
.If(vpn0_or_2M
):
90 m
.d
.comb
+= [ self
.lu_content_o
.eq(content
),
91 self
.lu_is_2M_o
.eq(tags
.is_2M
),
99 replace_valid
= Signal(reset_less
=True)
100 m
.d
.comb
+= replace_valid
.eq(self
.update_i
.valid
& self
.replace_en_i
)
103 with m
.If (self
.flush_i
):
104 # invalidate (flush) conditions: all if zero or just this ASID
105 with m
.If (self
.lu_asid_i
== Const(0, self
.asid_width
) |
106 (self
.lu_asid_i
== tags
.asid
)):
107 m
.d
.sync
+= tags
.valid
.eq(0)
110 with m
.Elif(replace_valid
):
111 m
.d
.sync
+= [ # update tag array
112 tags
.asid
.eq(self
.update_i
.asid
),
113 tags
.vpn2
.eq(self
.update_i
.vpn
[18:27]),
114 tags
.vpn1
.eq(self
.update_i
.vpn
[9:18]),
115 tags
.vpn0
.eq(self
.update_i
.vpn
[0:9]),
116 tags
.is_1G
.eq(self
.update_i
.is_1G
),
117 tags
.is_2M
.eq(self
.update_i
.is_2M
),
119 # and content as well
120 content
.eq(self
.update_i
.content
.flatten())
125 return [self
.flush_i
,
127 self
.lu_is_2M_o
, self
.lu_is_1G_o
, self
.lu_hit_o
,
128 ] + self
.update_i
.content
.ports() + self
.update_i
.ports()