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
16 self
.is_512G
= 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_512G_o
= Signal()
45 self
.lu_is_2M_o
= Signal()
46 self
.lu_is_1G_o
= Signal()
47 self
.lu_hit_o
= Signal()
49 def elaborate(self
, platform
):
52 tags
= TLBEntry(self
.asid_width
)
53 content
= Signal(self
.pte_width
)
55 m
.d
.comb
+= [self
.lu_hit_o
.eq(0),
56 self
.lu_is_2M_o
.eq(0),
57 self
.lu_is_1G_o
.eq(0)]
59 # temporaries for 1st level match
60 asid_ok
= Signal(reset_less
=True)
61 vpn2_ok
= Signal(reset_less
=True)
62 tags_ok
= Signal(reset_less
=True)
63 vpn2_hit
= Signal(reset_less
=True)
64 m
.d
.comb
+= [tags_ok
.eq(tags
.valid
),
65 asid_ok
.eq(tags
.asid
== self
.lu_asid_i
),
66 vpn2_ok
.eq(tags
.vpn2
== self
.vpn2
),
67 vpn2_hit
.eq(tags_ok
& asid_ok
& vpn2_ok
)]
68 # temporaries for 2nd level match
69 vpn1_ok
= Signal(reset_less
=True)
70 tags_2M
= Signal(reset_less
=True)
71 vpn0_ok
= Signal(reset_less
=True)
72 vpn0_or_2M
= Signal(reset_less
=True)
73 m
.d
.comb
+= [vpn1_ok
.eq(self
.vpn1
== tags
.vpn1
),
74 tags_2M
.eq(tags
.is_2M
),
75 vpn0_ok
.eq(self
.vpn0
== tags
.vpn0
),
76 vpn0_or_2M
.eq(tags_2M | vpn0_ok
)]
77 # TODO temporaries for 3rd level match
79 # first level match, this may be a giga page,
80 # check the ASID flags as well
83 with m
.If (tags
.is_1G
):
84 m
.d
.comb
+= [ self
.lu_content_o
.eq(content
),
85 self
.lu_is_1G_o
.eq(1),
88 # not a giga page hit so check further
90 # this could be a 2 mega page hit or a 4 kB hit
92 with m
.If(vpn0_or_2M
):
93 m
.d
.comb
+= [ self
.lu_content_o
.eq(content
),
94 self
.lu_is_2M_o
.eq(tags
.is_2M
),
102 replace_valid
= Signal(reset_less
=True)
103 m
.d
.comb
+= replace_valid
.eq(self
.update_i
.valid
& self
.replace_en_i
)
106 with m
.If (self
.flush_i
):
107 # invalidate (flush) conditions: all if zero or just this ASID
108 with m
.If (self
.lu_asid_i
== Const(0, self
.asid_width
) |
109 (self
.lu_asid_i
== tags
.asid
)):
110 m
.d
.sync
+= tags
.valid
.eq(0)
113 with m
.Elif(replace_valid
):
114 m
.d
.sync
+= [ # update tag array
115 tags
.asid
.eq(self
.update_i
.asid
),
116 tags
.vpn2
.eq(self
.update_i
.vpn
[18:27]),
117 tags
.vpn1
.eq(self
.update_i
.vpn
[9:18]),
118 tags
.vpn0
.eq(self
.update_i
.vpn
[0:9]),
119 tags
.is_512G
.eq(self
.update_i
.is_512G
),
120 tags
.is_1G
.eq(self
.update_i
.is_1G
),
121 tags
.is_2M
.eq(self
.update_i
.is_2M
),
123 # and content as well
124 content
.eq(self
.update_i
.content
.flatten())
129 return [self
.flush_i
,
131 self
.lu_is_2M_o
, self
.lu_is_1G_o
,self
.lu_is_512G_o
, self
.lu_hit_o
,
132 ] + self
.update_i
.content
.ports() + self
.update_i
.ports()