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Table 10-4. Valid THRM1 and THRM2 Bit Settings
TlN 1
TIV1
TID
TIE
V
Description
x
x
x
x
a
The threshold in the SPR will not be used for comparison.
x
x
x
a
1
Threshold is used for comparison, thermal management interrupt
assertion is disabled.
x
x
a
a
1
Set TIN and do not assert thermal management interrupt if the
junction temperature exceeds the threshold.
x
x
a
1
1
Set TIN and assert thermal management interrupt if the junction
temperature exceeds the threshold.
x
x
1
a
1
Set TIN and do not assert thermal management interrupt if the
junction temperature is less than the threshold.
x
x
1
1
1
Set TIN and assert thermal management interrupt if the junction
temperature is less than the threshold.
x
a
x
x
1
The state of the TIN bit is not valid.
a
1
a
x
1
The junction temperature is less than the threshold and as a result
the thermal management interrupt is not generated for TIE
=
1.
1
1
a
x
1
The junction temperature is greater than the threshold and as a
result the thermal management interrupt is generated if TIE
=
1.
a
1
1
x
1
The junction temperature is greater than the threshold and as a
result the thermal management interrupt is not generated for TIE
=
1.
1
1
1
x
1
The junction temperature is less than the threshold and as a result
the thermal management interrupt is generated if TIE
=
1.
Note: 1The TIN and TIV bits are read-only status bits.
10.3.2.2 TAU Dual-Threshold Mode
The configuration and operation of the TAU's dual-threshold mode is similar to single
threshold mode, except both THRMI and THRM2 are configured with desired threshold
and TID values, and the TIE and V bits are set to 1. When the THRM3[E] bit is set to 1 to
enable temperature measurement and comparison, the first comparison is made with
THRM1. If no thermal management interrupt results from the comparison, the number of
processor cycles specified in THRM3[SITV] elapses, and the next comparison is made with
THRM2. If no thermal management interrupt results from the THRM2 comparison, the
time specified by THRM3[SITV] again elapses, and the comparison returns to THRM1.
This sequence of comparisons continues until a thermal management interrupt occurs, or
the TAU is disabled. When a comparison results in an interrupt, the comparison with the
threshold SPR causing the interrupt is halted, but comparisons continue with the other
threshold SPR. Following a thermal management interrupt, the interrupt service routine
must read both THRMI and THRM2 to determine which threshold was crossed. Note that
it is possible for both threshold values to have been crossed, in which case the TAU ceases
making temperature comparisons until an mtspr instruction is executed to one or both of
the threshold SPRs.
Chapter 10. Power and Thermal Management
10-9
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