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The Intel Timed IO PPS generator driver outputs a PPS signal using dedicated hardware that is more accurate than software actuated PPS. The Timed IO hardware generates output events using the ART timer. The ART timer period varies based on platform type, but is less than 100 nanoseconds for all current platforms. Timed IO output accuracy is within 1 ART period. PPS output is enabled by writing '1' the 'enable' sysfs attribute. The driver uses hrtimers to schedule a wake-up 10 ms before each event (edge) target time. At wakeup, the driver converts the target time in terms of CLOCK_REALTIME to ART trigger time and writes this to the Timed IO hardware. The Timed IO hardware generates an event precisely at the requested system time without software involvement. Co-developed-by: Christopher Hall <christopher.s.hall@intel.com> Signed-off-by: Christopher Hall <christopher.s.hall@intel.com> Co-developed-by: Pandith N <pandith.n@intel.com> Signed-off-by: Pandith N <pandith.n@intel.com> Co-developed-by: Thejesh Reddy T R <thejesh.reddy.t.r@intel.com> Signed-off-by: Thejesh Reddy T R <thejesh.reddy.t.r@intel.com> Signed-off-by: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com> Reviewed-by: Eddie Dong <eddie.dong@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Rodolfo Giometti <giometti@enneenne.com> Signed-off-by: Subramanian Mohan <subramanian.mohan@intel.com> Link: https://lore.kernel.org/r/20250219040618.70962-3-subramanian.mohan@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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 reStructuredText 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.