0962b1fa5d
When accessing register with multiple bit fields, the common approach is
to use clrsetbits_le32, for example:
clrsetbits(®, (1 << 0) | (0x3 << 1) | (0x7 << 10),
(1 << 0) | (0x1 << 1) | (0x5 << 10));
This hard to maintain because we have to calculate the mask values
manually, make sure the duplicated shift (offset) was set correctly.
And it may be even worse if the value to set will be based on some
runtime values (that many developers will do a if-block with two very
similar argument list), and leaving lots of magic numbers.
We want to encourage developers always giving field names, and have a
better way of setting fields. The proposed utility macros are:
DEFINE_BITFIELD(name, high_bit, low_bit)
EXTRACT_BITFIELD(value, name)
WRITE32_BITFIELDS(addr, name, value, [name2, value2, ...])
READ32_BITFIELD(addr, name)
Where a developer can easily convert from data sheet like
BITS NAME
26:24 SEC_VIO
Into a declaration
DEFINE_BITFIELD(SEC_VIO, 26, 24)
Then, a simple call can set the field as:
WRITE32_BITFIELDS(®, SEC_VIO, 2);
That is much easier to understand than
clrsetbits_le32(®, 0x7 << 24, 0x2 << 24);
And to extract the value:
READ32_BITFIELD(®, SEC_VIO)
That is equivalent to:
(read32(®) & 0x3) >> 24
Change-Id: I8a1b17142f7a7dc6c441b0b1ee67d60d73ec8cc8
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35463
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
|
||
|---|---|---|
| 3rdparty | ||
| Documentation | ||
| configs | ||
| payloads | ||
| src | ||
| util | ||
| .checkpatch.conf | ||
| .clang-format | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmodules | ||
| .gitreview | ||
| AUTHORS | ||
| COPYING | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc | ||
| README.md | ||
| gnat.adc | ||
| toolchain.inc | ||
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:
- https://www.coreboot.org/Supported_Motherboards
- https://www.coreboot.org/Supported_Chipsets_and_Devices
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_TOOLCHAINKconfig 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 menuconfigandmake 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:
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.