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The ARTPEC-8 has an MCT with 4 global and 8 local timer interrupts. The SoC has a quad-core Cortex-A53 and a single-core Cortex-A5 which share one MCT with one global and eight local timers. The Cortex-A53 and Cortex-A5 do not have cache-coherency between them, and therefore run two separate kernels. The Cortex-A53 boots first and starts the global free-running counter and also registers a clock events device using the global timer. (This global timer clock events is usually replaced by arch timer clock events for each of the cores.) When the A5 boots (via the A53), it should not use the global timer interrupts or write to the global timer registers. This is because even if there are four global comparators, the control bits for all four are in the same registers, and we would need to synchronize between the cpus. Instead, the global timer FRC (already started by the A53) should be used as the clock source, and one of the local timers which are not used by the A53 can be used for clock events on the A5. To support this hardware, add a compatible for the MCT as well as two new properties to describe the hardware-mandated sharing of the FRC and dedicating local timers to specific processors. Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> Link: https://lore.kernel.org/r/20220609112738.359385-2-vincent.whitchurch@axis.com Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.