[PATCH 5/6] x86, hwmon: Package Level Thermal/Power: pkgtemp documentation

leann.ogasawara at canonical.com leann.ogasawara at canonical.com
Tue Aug 31 01:18:27 UTC 2010

BugLink: https://bugs.launchpad.net/bugs/601073

Document for package level thermal hwmon driver.

Signed-off-by: Fenghua Yu <fenghua.yu at intel.com>
LKML-Reference: <1280448826-12004-6-git-send-email-fenghua.yu at intel.com>
Reviewed-by: Len Brown <len.brown at intel.com>
Signed-off-by: H. Peter Anvin <hpa at linux.intel.com>
(cherry picked from commit a3159864f2978bf2ace9cc787d73d315c98bbf9a)

Signed-off-by: Leann Ogasawara <leann.ogasawara at canonical.com>
 Documentation/hwmon/pkgtemp |   36 ++++++++++++++++++++++++++++++++++++
 1 files changed, 36 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/hwmon/pkgtemp

diff --git a/Documentation/hwmon/pkgtemp b/Documentation/hwmon/pkgtemp
new file mode 100644
index 0000000..c8e1fb0
--- /dev/null
+++ b/Documentation/hwmon/pkgtemp
@@ -0,0 +1,36 @@
+Kernel driver pkgtemp
+Supported chips:
+  * Intel family
+    Prefix: 'pkgtemp'
+    CPUID:
+    Datasheet: Intel 64 and IA-32 Architectures Software Developer's Manual
+               Volume 3A: System Programming Guide
+Author: Fenghua Yu
+This driver permits reading package level temperature sensor embedded inside
+Intel CPU package. The sensors can be in core, uncore, memory controller, or
+other components in a package. The feature is first implemented in Intel Sandy
+Bridge platform.
+Temperature is measured in degrees Celsius and measurement resolution is
+1 degree C. Valid temperatures are from 0 to TjMax degrees C, because the actual
+value of temperature register is in fact a delta from TjMax.
+Temperature known as TjMax is the maximum junction temperature of package.
+We get this from MSR_IA32_TEMPERATURE_TARGET. If the MSR is not accessible,
+we define TjMax as 100 degrees Celsius. At this temperature, protection
+mechanism will perform actions to forcibly cool down the package. Alarm
+may be raised, if the temperature grows enough (more than TjMax) to trigger
+the Out-Of-Spec bit. Following table summarizes the exported sysfs files:
+temp1_input	  - Package temperature (in millidegrees Celsius).
+temp1_max        - All cooling devices should be turned on.
+temp1_crit	  - Maximum junction temperature (in millidegrees Celsius).
+temp1_crit_alarm - Set when Out-of-spec bit is set, never clears.
+		    Correct CPU operation is no longer guaranteed.

More information about the kernel-team mailing list