Add buffer_to/from_fifo32(_prefix) helpers

Many peripheral drivers across different SoCs regularly face the same
task of piping a transfer buffer into (or reading it out of) a 32-bit
FIFO register. Sometimes it's just one register, sometimes a whole array
of registers. Sometimes you actually transfer 4 bytes per register
read/write, sometimes only 2 (or even 1). Sometimes writes need to be
prefixed with one or two command bytes which makes the actual payload
buffer "misaligned" in relation to the FIFO and requires a bunch of
tricky bit packing logic to get right. Most of the times transfer
lengths are not guaranteed to be divisible by 4, which also requires a
bunch of logic to treat the potential unaligned end of the transfer
correctly.

We have a dozen different implementations of this same pattern across
coreboot. This patch introduces a new family of helper functions that
aims to solve all these use cases once and for all (*fingers crossed*).

Change-Id: Ia71f66c1cee530afa4c77c46a838b4de646ffcfb
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34850
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
5 files changed
tree: 2c4fc9e51c6c38c9d7a10a91083c961fd914471e
  1. .checkpatch.conf
  2. .clang-format
  3. .gitignore
  4. .gitmodules
  5. .gitreview
  6. 3rdparty/
  7. AUTHORS
  8. COPYING
  9. Documentation/
  10. MAINTAINERS
  11. Makefile
  12. Makefile.inc
  13. README.md
  14. configs/
  15. gnat.adc
  16. payloads/
  17. src/
  18. toolchain.inc
  19. util/
README.md

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.

Payloads

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

See https://www.coreboot.org/Payloads 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)

Optional:

  • 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 https://www.coreboot.org/Build_HOWTO 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 https://www.coreboot.org/QEMU 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:

https://www.coreboot.org

You can contact us directly on the coreboot mailing list:

https://www.coreboot.org/Mailinglist

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.