Tp smapi

The tp_smapi kernel module exposes some features of the ThinkPad's SMAPI functionality via a sysfs interface. Currently, the implemented functionality is control of battery charging, extended battery status and control of CD/DVD speed (disabled by default). For old ThinkPad models, see also tpctl. ATTENTION! This driver uses undocumented features and direct hardware access. They thus cannot be guaranteed to work, and may cause arbitrary damage (though so far none was reported)..

Features

• Battery charge/discharge control
• Battery status information
• Optical drive speed control (disabled by default)

Project Homepage / Availability

• Project page: http://tpctl.sourceforge.net/
• You need to download only the tp_smapi kernel module.

Installation

For testing, you can simply compile and load the driver within the current working directory:

# tar xzvf tp_smapi-0.16.tgz

# cd tp_smapi-0.16

# make load

To compile and install into the kernel's module path:

# make install

If you use the HDAPS driver, add HDAPS=1 to also patch the hdaps for compatibility with tp_smapi (this requires a kernel source tree):

# make load HDAPS=1   or   # make install HDAPS=1

To prepare a stand-alone patch against the current kernel tree (including a compatibility fixes to hdaps and Kconfig entries):

# make patch

To delete all autogenerated files:

# make clean

The original kernel tree is never modified by any these commands. The /lib/modules directory is modified only by # make install.

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

Hint:

Battery charging thresholds can be used to keep Li-Ion ad Li-Polymer batteries partially charged, in order to increase their lifetime.

To unconditionally inhibit charging for 17 minutes:

# echo 17 > /sys/devices/platform/smapi/BAT0/inhibit_charge_minutes

Hint:

Charge inhibiting can be used to reduce the power draw of the laptop, in order to use a an under-spec power supply that can't handle the combined power draw of running and charging. It can also be used to control which battery is charged when using an Ultrabay battery.

To cancel charge inhibiting:

# echo 0 > /sys/devices/platform/smapi/BAT0/inhibit_charge_minutes

To force battery discharging even if connected to AC, use one of these:

# echo 1 > /sys/devices/platform/smapi/BAT0/force_discharge

Hint:

This can be used to choose which battery is discharged when using an UltraBay battery.

To cancel forced discharge:

# echo 0 > /sys/devices/platform/smapi/BAT0/force_discharge

Battery status features

To view extended battery status such as charging state, voltage, current, capacity, cycle count and model information:

# cat /sys/devices/platform/smapi/BAT0/installed
# cat /sys/devices/platform/smapi/BAT0/state       # idle/charging/discharging
# cat /sys/devices/platform/smapi/BAT0/cycle_count 
# cat /sys/devices/platform/smapi/BAT0/current_now # instantaneous current
# cat /sys/devices/platform/smapi/BAT0/current_avg # last minute average
# cat /sys/devices/platform/smapi/BAT0/power_now   # instantaneous power
# cat /sys/devices/platform/smapi/BAT0/power_avg   # last minute average
# 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 is also available, including some fields not listed 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.

Note that the battery status readout conflicts with the stock hdaps driver, so if you use hdaps you will need to load tp_smapi using # make load HDAPS=1 (see Conflict with hdaps below).

On ACPI-enabled systems, most of above information is also available through the files under /proc/acpi/battery. The ACPI interface does not include the instantaneous power and cycle count readouts, and does not work well when hotswapping UltraBay batteries.

Optical drive control features

To control the speed of the optical drive:

# echo 0 > /sys/devices/platform/smapi/cd_speed # slow

# echo 1 > /sys/devices/platform/smapi/cd_speed # medium

# echo 2 > /sys/devices/platform/smapi/cd_speed # fast

# cat /sys/devices/platform/smapi/cd_speed

Enabling this feature

Changing the drive speed when a disc is being accessed will hang your computer. This feature is thus disabled by default, but can be enabled using by adding #define PROVIDE_CD_SPEED at the top of tp_smapi.c. The safe way to set the drive speed is using hdparm -E num or eject -x num for CD-ROM, and speedcontrol -x num (sourcecode here) for DVD. For kernels older than 2.6.15, this may require the libata pass-through patch.

Features not yet implemented

Other things that can be controlled through SMAPI, but are not supported in this version of the driver, include PCI bus power saving, CPU power saving control and fan control (the latter is available through an alternative method). 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).

The tp_smapi package includes a patch against hdaps to make it compatible with tp_smapi. To build the patched version, append the HDAPS=1 parameter to the make command, for example: # make load HDAPS=1 (see Installation above).

If you don't do that:

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. To switch between the two, rmmod both and then load one you need.

Some of the battery status is also visible through ACPI (/proc/acpi/battery/*).

The charging control files (*_charge_thresh, inhibit_charge_minutes and force_discharge*) don't have this problem.

Model-specific status

tp_smapi feature support matrix

×	start_charge_ thresh	stop_charge_ thresh	inhbit_charge_ minutes	force_discharge	battery status files (see note about hdaps above)	cd_speed (see note above)
A series
A30	no	no	no	no	yes	unknown
G series
G41	yes	no	yes	unknown	unknown	yes
R series
R40	no	no	no	no	unknown	yes
R50	unknown	no	unknown	unknown	yes	unknown
R50p	no	no	no	no	yes	yes
R51	yes	no	yes	unknown	yes	unknown
R52	yes	yes	yes	unknown	unknown	yes
T series
T22	no	no	no	no	no	unknown
T23	no	no	no	no	yes	unknown
T40	no	no	no	unknown	yes	yes
T40p	no	no	no	no	yes	yes
T41	no	no	no	no	yes	yes
T41p	no	no	no	unknown	unknown	yes
T42	yes	no	yes	yes	yes	yes
T42p	yes	no	yes	unknown	unknown	unknown
T43	yes	yes	yes	yes	yes	yes
T43p	yes	yes	yes	yes	yes	yes
X series
X24	no	no	no	unknown	yes	unknown
X31	no	no	no	unknown	yes	unknown
X32	no	no	no	unknown	unknown	unknown
X40	yes	no	yes	unknown	yes	unknown
X41	yes	yes	yes	yes	yes	unknown

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.

Tools using this driver

The driver's interface can be accessed directly through the files under /sys/devices/platform/smapi, or via the following tools:

• KThinkBat - display battery status on the KDE kicker panel.
• gkrellm-ThinkBat - battery status plugin for Gkrellm2