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Commit a3159864f2978bf2ace9cc787d73d315c98bbf9a

Authored by Fenghua Yu
Committed by H. Peter Anvin
1 parent 0199114c31
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

x86, hwmon: Package Level Thermal/Power: pkgtemp documentation 

Document for package level thermal hwmon driver.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
LKML-Reference: <1280448826-12004-6-git-send-email-fenghua.yu@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

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Documentation/hwmon/pkgtemp
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  1 +Kernel driver pkgtemp
  2 +======================
  3 +
  4 +Supported chips:
  5 + * Intel family
  6 + Prefix: 'pkgtemp'
  7 + CPUID:
  8 + Datasheet: Intel 64 and IA-32 Architectures Software Developer's Manual
  9 + Volume 3A: System Programming Guide
  10 +
  11 +Author: Fenghua Yu
  12 +
  13 +Description
  14 +-----------
  15 +
  16 +This driver permits reading package level temperature sensor embedded inside
  17 +Intel CPU package. The sensors can be in core, uncore, memory controller, or
  18 +other components in a package. The feature is first implemented in Intel Sandy
  19 +Bridge platform.
  20 +
  21 +Temperature is measured in degrees Celsius and measurement resolution is
  22 +1 degree C. Valid temperatures are from 0 to TjMax degrees C, because the actual
  23 +value of temperature register is in fact a delta from TjMax.
  24 +
  25 +Temperature known as TjMax is the maximum junction temperature of package.
  26 +We get this from MSR_IA32_TEMPERATURE_TARGET. If the MSR is not accessible,
  27 +we define TjMax as 100 degrees Celsius. At this temperature, protection
  28 +mechanism will perform actions to forcibly cool down the package. Alarm
  29 +may be raised, if the temperature grows enough (more than TjMax) to trigger
  30 +the Out-Of-Spec bit. Following table summarizes the exported sysfs files:
  31 +
  32 +temp1_input - Package temperature (in millidegrees Celsius).
  33 +temp1_max - All cooling devices should be turned on.
  34 +temp1_crit - Maximum junction temperature (in millidegrees Celsius).
  35 +temp1_crit_alarm - Set when Out-of-spec bit is set, never clears.
  36 + Correct CPU operation is no longer guaranteed.