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74fedbe377
With a SPI clock above about 24MHz the APB cannot keep up when doing individual byte transfers. Adjust the driver to use 16-bit reads when it can, to remove this bottleneck. Any transaction which involves writing bytes still uses 8-bit transfers, to simplify the code. These are the transfers that are not time-critical since they tend to be small. The case that really matters is reading from SPI flash. In general we can use 16-bit reads anytime we are transferring an even number of bytes. If the code detects an odd number of bytes, it tries to perform the operation in two steps: once in 16-bit mode with an even number of bytes, and once in 8-bit mode for the final byte. This allow us to use 16-bit reads even if asked to transfer (for example) 0xf423 bytes. The limit on in_now and out_now is adjusted to 0xfffe to avoid an extra transfer when transferring ~>=64KB. CQ-DEPEND=CL:383232 BUG=chrome-os-partner:56556 BRANCH=none TEST=boot on gru and see that things still work correctly. I tested (with extra debugging) that the 16-bit case is being picked when it should be. Change-Id: If5effae9a84e4de06537fd594bedf7f01d6a9c88 Signed-off-by: Patrick Georgi <pgeorgi@chromium.org> Original-Commit-Id: ec250b4931c7d99cc014e32ab597fca948299d08 Original-Change-Id: Idc5b7e5d82cdbdc1e8fe8b2d6da819edf2d5570c Original-Signed-off-by: Simon Glass <sjg@chromium.org> Original-Reviewed-on: https://chromium-review.googlesource.com/381312 Original-Commit-Ready: Julius Werner <jwerner@chromium.org> Original-Tested-by: Julius Werner <jwerner@chromium.org> Original-Reviewed-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/16712 Tested-by: build bot (Jenkins) Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: Martin Roth <martinroth@google.com> |
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| payloads | ||
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| .clang-format | ||
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| .gitreview | ||
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| gnat.adc | ||
| MAINTAINERS | ||
| Makefile | ||
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| README | ||
| toolchain.inc | ||
------------------------------------------------------------------------------- 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 http://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: * http://www.coreboot.org/Supported_Motherboards * http://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_TOOLCHAIN Kconfig option if you're feeling lucky (no support in this case). * iasl (for targets with ACPI support) 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 http://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 http://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: http://www.coreboot.org You can contact us directly on the coreboot mailing list: http://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.