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authorHenrique de Moraes Holschuh <hmh@hmh.eng.br>2007-04-24 10:48:16 -0400
committerLen Brown <len.brown@intel.com>2007-04-25 02:00:27 -0400
commit2c37aa4e22dd55070c608290c5031f2ee93e69ce (patch)
treeab8a0c05c4a3e51e6f111d3377393b766d4e39a2 /Documentation
parent40ca9fdf8aa7d929e2b8939be1e6380d107381e1 (diff)
ACPI: thinkpad-acpi: add sysfs support to the thermal subdriver
Export thinkpad thermal sensors to sysfs, following the hwmon specification for thermal monitoring sensors. ThinkPad thermal monitoring is done by the EC. Sensors can show up or disappear at runtime when they are inside hotswappable hardware, such as batteries. Sensors that are not available return -ENXIO when accessed. Up to 16 thermal sensors are supported on new firmware (but nobody has reported a ThinkPad with more than 12 sensors so far), and 8 sensors are supported on older firmware. Thermal sensor mapping is model-specific. Precision varies, it is 1 degree Celcius on new ThinkPads, but higher on some older models. Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/thinkpad-acpi.txt26
1 files changed, 20 insertions, 6 deletions
diff --git a/Documentation/thinkpad-acpi.txt b/Documentation/thinkpad-acpi.txt
index cc079afaf66b..80c0bf28e392 100644
--- a/Documentation/thinkpad-acpi.txt
+++ b/Documentation/thinkpad-acpi.txt
@@ -458,17 +458,17 @@ X40:
458 16 - one medium-pitched beep repeating constantly, stop with 17 458 16 - one medium-pitched beep repeating constantly, stop with 17
459 17 - stop 16 459 17 - stop 16
460 460
461Temperature sensors -- /proc/acpi/ibm/thermal 461Temperature sensors
462--------------------------------------------- 462-------------------
463
464procfs: /proc/acpi/ibm/thermal
465sysfs device attributes: (hwmon) temp*_input
463 466
464Most ThinkPads include six or more separate temperature sensors but 467Most ThinkPads include six or more separate temperature sensors but
465only expose the CPU temperature through the standard ACPI methods. 468only expose the CPU temperature through the standard ACPI methods.
466This feature shows readings from up to eight different sensors on older 469This feature shows readings from up to eight different sensors on older
467ThinkPads, and it has experimental support for up to sixteen different 470ThinkPads, and it has experimental support for up to sixteen different
468sensors on newer ThinkPads. Readings from sensors that are not available 471sensors on newer ThinkPads.
469return -128.
470
471No commands can be written to this file.
472 472
473EXPERIMENTAL: The 16-sensors feature is marked EXPERIMENTAL because the 473EXPERIMENTAL: The 16-sensors feature is marked EXPERIMENTAL because the
474implementation directly accesses hardware registers and may not work as 474implementation directly accesses hardware registers and may not work as
@@ -525,6 +525,20 @@ The A31 has a very atypical layout for the thermal sensors
5258: Bay Battery: secondary sensor 5258: Bay Battery: secondary sensor
526 526
527 527
528Procfs notes:
529 Readings from sensors that are not available return -128.
530 No commands can be written to this file.
531
532Sysfs notes:
533 Sensors that are not available return the ENXIO error. This
534 status may change at runtime, as there are hotplug thermal
535 sensors, like those inside the batteries and docks.
536
537 thinkpad-acpi thermal sensors are reported through the hwmon
538 subsystem, and follow all of the hwmon guidelines at
539 Documentation/hwmon.
540
541
528EXPERIMENTAL: Embedded controller register dump -- /proc/acpi/ibm/ecdump 542EXPERIMENTAL: Embedded controller register dump -- /proc/acpi/ibm/ecdump
529------------------------------------------------------------------------ 543------------------------------------------------------------------------
530 544