
8-22
G2 PowerPC Core Reference Manual
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MOTOROLA
Signal Descriptions
When HID0[ABE] is set, the G2 core performs address-only bus transactions with the
encodings shown in Table 8-7.
8.3.4.2
Transfer Size (core_tsiz[0:2])—Output
The core_tsiz[0:2] signals consist of three output signals on the G2 core. Following are the
state meaning and timing comments for the core_tsiz[0:2] outputs.
State Meaning
Asserted/Negated—For memory accesses, these signals along with
core_tbst_out, indicate the data transfer size for the current bus
operation, as shown in Table 8-8. Table 9-5 shows how the transfer
Single-beat read
Caching-inhibited
load or instruction
fetch
0
1
0
1
0
Read
Single-beat read
or burst
Burst
Load miss, store
miss, or
instruction fetch
0
1
1
1
0
Read-with-intent-to-
modify
Burst
Single-beat write
stwcx.
1
0
0
1
0
Write-with-flush-
atomic
Single-beat
write
N/A
N/A
1
0
1
1
0
Reserved
N/A
Single-beat read
lwarx
(caching-inhibited
load)
1
1
0
1
0
Read-atomic
Single-beat read
or burst
Burst
lwarx
(load miss)
1
1
1
1
0
Read-with-intent-to-
modify-atomic
Burst
N/A
N/A
0
0
0
1
1
Reserved
—
N/A
N/A
0
0
1
1
1
Reserved
—
N/A
N/A
0
1
0
1
1
Read-with-no-intent-
to-cache
Single-beat read
or burst
N/A
N/A
0
1
1
1
1
Reserved
—
N/A
N/A
1
X
X
1
1
Reserved
—
Table 8-7. Implementation-Specific Transfer Type Encoding
Transaction
Source
core_tt_out[0:4]
x
Bus Command
Transaction Type
tt0
tt1
tt2
tt3
tt4
dcbst
0
0
0
0
0
Clean block
Address only
dcbf
0
0
1
0
0
Flush block
Address only
dcbz
,
dcbi
1
1
The
dcbi
instruction should never be used on the G2 core.
0
1
1
0
0
Kill block
Address only
Table 8-6. Transfer Type Encoding for the G2 Core as a Bus Master (continued)
G2 Core Bus
Master
Transaction
Transaction
Source
core_tt_out
x
60x Bus
Specification
Command
Transaction
Type
tt0
tt1
tt2
tt3
tt4
F
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