prevent overheating.
When sensor 0's alarm interrupt is fired, set a throttle flag. Further
requests to set CPU frequency will be rejected until sensor 0's temperature
returns to a level below the hot temperature threshold.
Relnotes: yes
The A83T thermal sensor controller has three sensors. Sensor 0 corresponds
to CPU cluster 0, sensor 1 to CPU cluster 1, and sensor 2 to the GPU. This
driver exports the temperature sensor readings via sysctl.
Calibration data is obtained from SRAM found in the Secure ID module.
Reviewed by: manu
Differential Revision: https://reviews.freebsd.org/D6378
