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e28edc5719
The remote processors in OMAP4+ SoCs are equipped with internal timers, like the internal SysTick timer in a Cortex M3/M4 NVIC or the CTM timer within Unicache in IPU & DSP. However, these timers are gated when the processor subsystem clock is gated, making them rather difficult to use as OS tick sources. They will not be able to wakeup the processor from any processor-sleep induced clock-gating states. This can be avoided by using an external timer as the tick source, which can be controlled independently by the OMAP remoteproc driver code, but still allowing the processor subsystem clock to be auto-gated when the remoteproc cores are idle. This patch adds the support for OMAP remote processors to request timer(s) to be used by the remoteproc. The timers are enabled and disabled in line with the enabling/disabling of the remoteproc. The timer data is not mandatory if the advanced device management features are not required. The core timer functionality is provided by the OMAP DMTimer clocksource driver, which does not export any API. The logic is implemented through the timer device's platform data ops. The OMAP remoteproc driver mainly requires ops to request/free a dmtimer, and to start/stop a timer. The split ops helps in controlling the timer state without having to request and release a timer everytime it needs to use the timer. NOTE: If the gptimer is already in use by the time IPU and/or DSP are loaded, the processors will fail to boot. Signed-off-by: Suman Anna <s-anna@ti.com> Signed-off-by: Tero Kristo <t-kristo@ti.com> Reviewed-by: Andrew F. Davis <afd@ti.com> Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org> Link: https://lore.kernel.org/r/20200324110035.29907-11-t-kristo@ti.com Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> |
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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.