coreboot/payloads/libpayload
Subrata Banik 893a2b008a libpayload: Add coreboot boot mode table
This commit adds a new coreboot table, CB_TAG_BOOT_MODE, to pass
platform boot mode information to the payload.

The new table defines flags for low-battery mode and off-mode charging,
which are essential for a payload to properly initialize the charger
driver.

The cb_parse_boot_mode function is added to read this information, and
the sysinfo_t structure is updated to store the parsed boot mode data.

This ensures that the payload can accurately determine the system's
power state at boot and payload operations are also in sync with the
boot firmware.

The following scenarios were tested and verified:

Scenario 1: Low-battery, no charger
 - coreboot detects the low-battery state and performs an immediate
   shutdown after displaying the low-battery splash screen.

Scenario 2: Low-battery, charger attached
 - coreboot detects the low-battery state but continues booting because
   a charger is present. The payload receives the low-battery
   information (using the same source as coreboot) and correctly
   initiates the charging process.

Scenario 3: Off-mode charging
 - The system boots directly from an S5 state due to a charger being
   plugged in. coreboot detects the off-mode state, skips the firmware
   splash screen, and hands off control to the payload, which then
   starts charging.

Scenario 4: Normal boot
 - The system boots without any low-battery or off-mode conditions.
   coreboot and the payload both detect a normal boot (using the same
   information), bypass charging initialization, and proceed to boot the
   operating system.

TEST=Able to build and boot on google/quenbi device and verify the boot
mode flag is correctly passed.

Change-Id: Iec25c6fdfcdc5ea7c397d2430ac7b545e1e068f2
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/89015
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2025-09-05 04:22:27 +00:00
..
arch libpayload/arch/arm64/mmu: Fix missing CBMEM in used ranges 2025-06-13 15:23:09 +00:00
bin libpayload: Add x86_64 (64-bit) support 2024-05-26 01:26:31 +00:00
configs libpayload: configs: Add new config.featuretest to broaden CI 2024-12-04 22:25:34 +00:00
crypto payloads: Rename Makefiles from .inc to .mk 2024-01-24 10:15:10 +00:00
curses tree: Replace union {0} initializers with {} for C23 compliance 2025-08-11 16:40:34 +00:00
drivers libpayload/drivers/pci_qcom: Fix address during ATU config 2025-07-30 17:54:17 +00:00
gdb libpayload: gdb: Make die_if() format string a literal 2024-03-19 22:50:03 +00:00
include libpayload: Add coreboot boot mode table 2025-09-05 04:22:27 +00:00
libc libpayload: Add coreboot boot mode table 2025-09-05 04:22:27 +00:00
libcbfs libpayload: Remove legacy CBFS API 2024-02-22 21:18:39 +00:00
liblz4 payloads: Rename Makefiles from .inc to .mk 2024-01-24 10:15:10 +00:00
liblzma payloads: Rename Makefiles from .inc to .mk 2024-01-24 10:15:10 +00:00
libpci payloads: Rename Makefiles from .inc to .mk 2024-01-24 10:15:10 +00:00
sample libpayload: Add mock architecture 2021-10-11 12:59:57 +00:00
tests libpayload: Fix strsep() edge cases 2025-08-13 17:44:31 +00:00
vboot libpayload: Add x86_64 (64-bit) support 2024-05-26 01:26:31 +00:00
.gitignore .gitignore: Split into subdirectory files 2020-10-30 07:05:27 +00:00
Doxyfile
Kconfig libpayload: Use Kconfig instead of weak symbol for arch_ndelay() 2025-05-22 19:27:30 +00:00
LICENSE_GPL
LICENSES
Makefile tree: Replace scan-build by clang-tidy 2025-07-01 01:12:32 +00:00
Makefile.mk payloads/libpayload/Makefile.mk: Replace nm with $(NM) 2025-06-05 13:37:27 +00:00
Makefile.payload libpayload/Makefile.payload: Add lto flags 2024-08-27 09:08:07 +00:00
README payloads/libpayload: Update a Makefile for sample libpayload 2019-06-21 09:16:36 +00:00

-------------------------------------------------------------------------------
libpayload README
-------------------------------------------------------------------------------

libpayload is a minimal library to support standalone payloads
that can be booted with firmware like coreboot. It handles the setup
code, and provides common C library symbols such as malloc() and printf().

Note: This is _not_ a standard library for use with an operating system,
rather it's only useful for coreboot payload development!
See https://www.coreboot.org for details on coreboot.


Installation
------------

 $ git clone https://review.coreboot.org/coreboot.git

 $ cd coreboot/payloads/libpayload

 $ make menuconfig

 $ make

 $ make install (optional, will install into ./install per default)

On x86 systems, libpayload will always be 32-bit even if your host OS runs
in 64-bit, so you might have to install the 32-bit libgcc version.
On Debian systems you'd do 'apt-get install gcc-multilib' for example.

Run 'make distclean' before switching boards. This command will remove
your current .config file, so you need 'make menuconfig' again or
'make defconfig' in order to set up configuration. Default configuration
is based on 'configs/defconfig'. See the configs/ directory for examples
of configuration.


Usage
-----

Here's an example of a very simple payload (hello.c) and how to build it:

 #include <libpayload.h>

 int main(void)
 {
     printf("Hello, world!\n");
     return 0;
 }

Building the payload using the 'lpgcc' compiler wrapper:

 $ lpgcc -o hello.elf hello.c

Please see the sample/ directory for details.


Website and Mailing List
------------------------

The main website is https://www.coreboot.org/Libpayload.

For additional information, patches, and discussions, please join the
coreboot mailing list at https://www.coreboot.org/Mailinglist, where most
libpayload developers are subscribed.


Copyright and License
---------------------

See LICENSES.