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Documentation: driver-api: pps: Add Intel Timed I/O PPS generator

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Add Intel Timed I/O PPS usage instructions.

Co-developed-by: Pandith N <pandith.n@intel.com>
Signed-off-by: Pandith N <pandith.n@intel.com>
Signed-off-by: Lakshmi Sowjanya D <lakshmi.sowjanya.d@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/20250219040618.70962-4-subramanian.mohan@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Subramanian Mohan 2025-02-19 09:36:17 +05:30 committed by Greg Kroah-Hartman
parent c89755d111
commit 6b22c3de1c
1 changed files with 24 additions and 0 deletions
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Documentation/driver-api/pps.rst
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@ -285,3 +285,27 @@ delay between assert and clear edge as small as possible to reduce system
latencies. But if it is too small slave won't be able to capture clear edge
transition. The default of 30us should be good enough in most situations.
The delay can be selected using 'delay' pps_gen_parport module parameter.
Intel Timed I/O PPS signal generator
------------------------------------
Intel Timed I/O is a high precision device, present on 2019 and newer Intel
CPUs, that can generate PPS signals.
Timed I/O and system time are both driven by same hardware clock. The signal
is generated with a precision of ~20 nanoseconds. The generated PPS signal
is used to synchronize an external device with system clock. For example,
it can be used to share your clock with a device that receives PPS signal,
generated by Timed I/O device. There are dedicated Timed I/O pins to deliver
the PPS signal to an external device.
Usage of Intel Timed I/O as PPS generator:
Start generating PPS signal::
$echo 1 > /sys/class/pps-gen/pps-genx/enable
Stop generating PPS signal::
$echo 0 > /sys/class/pps-gen/pps-genx/enable