thermal: Intel SoC DTS thermal

thermal: Intel SoC DTS thermal

In the Intel SoCs like Bay Trail, there are 2 additional digital temperature
sensors(DTS), in addition to the standard DTSs in the core. Also they support
4 programmable thresholds, out of which two can be used by OSPM. These
thresholds can be used by OSPM thermal control. Out of these two thresholds,
one is used by driver and one user mode can change via thermal sysfs to get
notifications on threshold violations.

The driver defines one critical trip points, which is set to TJ MAX - offset.
The offset can be changed via module parameter (default 5C). Also it uses
one of the thresholds to get notification for this temperature violation.
This is very important for orderly shutdown as the many of these devices don't
have ACPI thermal zone, and expects that there is some other thermal control
mechanism present in OSPM. When a Linux distro is used without additional
specialized thermal control program, BIOS can do force shutdown when thermals
are not under control. When temperature reaches critical, the Linux thermal
core will initiate an orderly shutdown.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>