[coreboot] Battery thresholds on lenovo T400

Michal Widlok michalwd1979 at gmail.com
Mon Dec 12 16:58:10 CET 2016

Dear Members,

I looking for a way to set battery charge thresholds on T400 with
coreboot. I know that tp_smapi are not supported, but I found an
interesting thread (it's for X220, but I hope that my would be

The post says:
"tp smapi depends on lot of SMM/SMI code. So tp-smapi kernel module
asked the Lenovo BIOS to tell the EC to do something. coreboot don't
want to support SMM/SMI APIs, because they are quite dangerous.
But there is another way to get those features back.
We know how to enable it, but we haven't yet create a way to control
this by the user.

One thing could be a userspace tool executed as root or we add another
CMOS configuration for it. Any idea?"

Is that mean that EC in lenovo laptops is "known" enough to control
it, but coreboot is not ready to implement this functionality? An if
it is known the is there any literature/posts available that says how
to control it with ectool or something?

If there are any test needed to be done to help about this subject,
then I can do them on my laptop. Hardware flashing is possible also.
Very best regards,
Michael Widlok

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