Difference between revisions of "SMAPI support for Linux"
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Revision as of 16:12, 13 December 2005
ThinkPad laptops include a proprietary interface called SMAPI BIOS (System Management Application Program Interface) which provides some hardware control functionality that is not exposed by any other interface (e.g., ACPI).
The SMAPI interfaces changes a lot between models, and is poorly documented, so Linux support is not exhaustive for most models. There are currently two SMAPI access mechanisms available: thinkpad and tpctl for older ThinkPads, and tp_smapi for newer ones.
Using the tp_smapi module
The tp_smapi kernel module exposes some features of the SMAPI BIOS found on recent ThinkPads via a sysfs interface. Currently, the implemented functionality is control of battery charging (this is useful for increasing battery lifetime or for using a leftover under-spec power supply that can't handle the combined power draw of running and charging), and control of CD/DVD speed.
To compile and load the module:
# tar xzvf tp_smapi-0.09.tgz # cd tp_smapi-0.09 # make load
To install permanently (optional):
# make install # modprobe tp_smapi
Battery charge control features
To set the thresholds for starting and stopping battery charging (in percent of current full charge capacity):
# echo 40 > /sys/devices/platform/smapi/BAT0/start_charge_thresh # echo 70 > /sys/devices/platform/smapi/BAT0/stop_charge_thresh # cat /sys/devices/platform/smapi/BAT0/*_charge_thresh 40 70
To unconditionally inhibit charging for 17 minutes:
# echo 17 > /sys/devices/platform/smapi/BAT0/inhibit_charge_minutes
To cancel charge inhibiting:
# echo 0 > /sys/devices/platform/smapi/BAT0/inhibit_charge_minutes
Battery status features
To view exteded battery status (see below about conflict with hdaps):
# cat /sys/devices/platform/smapi/BAT0/installed # cat /sys/devices/platform/smapi/BAT0/cycle_count # cat /sys/devices/platform/smapi/BAT0/current1 # cat /sys/devices/platform/smapi/BAT0/current2 # cat /sys/devices/platform/smapi/BAT0/last_full_capacity # cat /sys/devices/platform/smapi/BAT0/remaining_capacity # cat /sys/devices/platform/smapi/BAT0/design_capacity # cat /sys/devices/platform/smapi/BAT0/voltage # cat /sys/devices/platform/smapi/BAT0/design_voltage # cat /sys/devices/platform/smapi/BAT0/manufacturer # cat /sys/devices/platform/smapi/BAT0/model # cat /sys/devices/platform/smapi/BAT0/serial # cat /sys/devices/platform/smapi/BAT0/barcoding # cat /sys/devices/platform/smapi/BAT0/chemistry # cat /sys/devices/platform/smapi/ac_connected
The raw status data, including some fields not in the above (in case you can figure them out):
# cat /sys/devices/platform/smapi/BAT0/dump
In all of the above, replace BAT0 with BAT1 to address the 2nd battery.
Optical drive control features
To control the speed of the optical drive:
# echo 0 > /sys/devices/platform/smapi/cdrom_speed # slow # echo 1 > /sys/devices/platform/smapi/cdrom_speed # medium # echo 2 > /sys/devices/platform/smapi/cdrom_speed # fast # cat /sys/devices/platform/smapi/cdrom_speed 2
Other things that can be controlled through SMAPI, but are not supported in this version of the driver, include forcing battery discharge, PCI bus power saving, CPU power saving control and fan control. See the included README file for more information.
Conflict with hdaps
The extended battery status function conflicts with the hdaps kernel module (they use the same IO ports). If you load hdaps first, tp_smapi will disable its battery status functions (and log a message in the kernel log). If you load tp_smapi first, hdaps will refuse to load. Use rmmod to switch between the two.
Some of the battery status is also visible through ACPI (/proc/acpi/battery/*).
The charging control files (*_charge_thresh and inhibit_charge_minutes) don't have this problem.
|×||start_charge_thresh||stop_charge_thresh||inhbit_charge_minutes||cdrom_speed||battery status files|
(see notice about hdaps above)
Please update the above and report your experience on the discussion page. If the module loads but gives a "not supported" or "not implementeded" when you try to use some specific file in /sys/devices/platform/smapi/, please report the dmesg output and whether the corresponding functionality is available under Windows - maybe your ThinkPad just can't do that.
Using the thinkpad module
This solution consists of a module, called thinkpad, and a user-space tool caled tpctl. It provides very rich functionality for older ThinkPads, but on newer ThinkPads much of this functionality is exposed and supported through an ACPI interface and the SMAPI access does not work anymore. Kernel 2.6.9 and newer is unsupported; for kernel 2.6.3 and newer you need tpctl >=4.14 and thinkpad >=5.5. For details, see the README and list of supported models.