chromeec: Disable battery remaining capacity workaround

If remaining charge is more than x% of the full capacity, the
remaining charge is raised to the full capacity before it's
reported to the rest of the system.

Some batteries don't update full capacity timely or don't update it
at all. On such systems, compensation is required to guarantee
the remaining charge will be equal to the full capacity eventually.

On some systems, Rohm charger generates audio noise when the battery
is fully charged and AC is plugged. A workaround is to do charge-
discharge cycles between 93 and 100%. On such systems, compensation
was also applied to mask this cycle from users.

This used to be done in ACPI, thus, all software components except EC
was able to see the compensated charge. This patch is part of the
effort of moving the logic to EC. With this and the EC changes, EC
can see what the rest of the system sees, thus, can control LEDs
synchronously (to the display percentage).

Another rationale of this move is EC can perform more granular and
precise compensation than ACPI since it has more knowledge about the
battery and the charger.

TEST=Verify charge LED changes to white (full) on Sona synchronously
to the display percentage.
TEST=Verify charge LED changes to blinking white (low) on Sona
within 30 seconds synchronously to the display percentage.

Change-Id: I0b51911b90dc2e7fcf5c730c54d9fda1fea76aa9
Signed-off-by: Daisuke Nojiri <>
Tested-by: build bot (Jenkins) <>
Reviewed-by: Duncan Laurie <>
1 file changed
tree: 8b5fc2c3787f06205a2a873e532ad0b39da289d5
  1. 3rdparty/
  2. configs/
  3. Documentation/
  4. payloads/
  5. src/
  6. util/
  7. .checkpatch.conf
  8. .clang-format
  9. .gitignore
  10. .gitmodules
  11. .gitreview
  13. gnat.adc
  15. Makefile

coreboot README

coreboot is a Free Software project aimed at replacing the proprietary BIOS (firmware) found in most computers. coreboot performs a little bit of hardware initialization and then executes additional boot logic, called a payload.

With the separation of hardware initialization and later boot logic, coreboot can scale from specialized applications that run directly firmware, run operating systems in flash, load custom bootloaders, or implement firmware standards, like PC BIOS services or UEFI. This allows for systems to only include the features necessary in the target application, reducing the amount of code and flash space required.

coreboot was formerly known as LinuxBIOS.


After the basic initialization of the hardware has been performed, any desired "payload" can be started by coreboot.

See for a list of supported payloads.

Supported Hardware

coreboot supports a wide range of chipsets, devices, and mainboards.

For details please consult:

Build Requirements

  • make
  • gcc / g++ Because Linux distribution compilers tend to use lots of patches. coreboot does lots of "unusual" things in its build system, some of which break due to those patches, sometimes by gcc aborting, sometimes - and that's worse - by generating broken object code. Two options: use our toolchain (eg. make crosstools-i386) or enable the ANY_TOOLCHAIN Kconfig option if you're feeling lucky (no support in this case).
  • iasl (for targets with ACPI support)
  • pkg-config
  • libssl-dev (openssl)


  • doxygen (for generating/viewing documentation)
  • gdb (for better debugging facilities on some targets)
  • ncurses (for make menuconfig and make nconfig)
  • flex and bison (for regenerating parsers)

Building coreboot

Please consult for details.

Testing coreboot Without Modifying Your Hardware

If you want to test coreboot without any risks before you really decide to use it on your hardware, you can use the QEMU system emulator to run coreboot virtually in QEMU.

Please see for details.

Website and Mailing List

Further details on the project, a FAQ, many HOWTOs, news, development guidelines and more can be found on the coreboot website:

You can contact us directly on the coreboot mailing list:

Copyright and License

The copyright on coreboot is owned by quite a large number of individual developers and companies. Please check the individual source files for details.

coreboot is licensed under the terms of the GNU General Public License (GPL). Some files are licensed under the "GPL (version 2, or any later version)", and some files are licensed under the "GPL, version 2". For some parts, which were derived from other projects, other (GPL-compatible) licenses may apply. Please check the individual source files for details.

This makes the resulting coreboot images licensed under the GPL, version 2.