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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>
37 lines
1.5 KiB
Plaintext
37 lines
1.5 KiB
Plaintext
Kernel driver pkgtemp
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======================
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Supported chips:
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* Intel family
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Prefix: 'pkgtemp'
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CPUID:
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Datasheet: Intel 64 and IA-32 Architectures Software Developer's Manual
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Volume 3A: System Programming Guide
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Author: Fenghua Yu
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Description
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-----------
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This driver permits reading package level temperature sensor embedded inside
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Intel CPU package. The sensors can be in core, uncore, memory controller, or
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other components in a package. The feature is first implemented in Intel Sandy
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Bridge platform.
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Temperature is measured in degrees Celsius and measurement resolution is
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1 degree C. Valid temperatures are from 0 to TjMax degrees C, because the actual
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value of temperature register is in fact a delta from TjMax.
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Temperature known as TjMax is the maximum junction temperature of package.
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We get this from MSR_IA32_TEMPERATURE_TARGET. If the MSR is not accessible,
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we define TjMax as 100 degrees Celsius. At this temperature, protection
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mechanism will perform actions to forcibly cool down the package. Alarm
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may be raised, if the temperature grows enough (more than TjMax) to trigger
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the Out-Of-Spec bit. Following table summarizes the exported sysfs files:
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temp1_input - Package temperature (in millidegrees Celsius).
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temp1_max - All cooling devices should be turned on.
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temp1_crit - Maximum junction temperature (in millidegrees Celsius).
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temp1_crit_alarm - Set when Out-of-spec bit is set, never clears.
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Correct CPU operation is no longer guaranteed.
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