On 10/31/24 9:35 AM, Rodolfo Giometti wrote:
> This patch adds some examples about how to register a new PPS
> generator in the system, and how to manage it.
>
> Signed-off-by: Rodolfo Giometti <giometti@xxxxxxxxxxxx>
> ---
> Documentation/driver-api/pps.rst | 40 ++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
>
> diff --git a/Documentation/driver-api/pps.rst b/Documentation/driver-api/pps.rst
> index 78dded03e5d8..dffa06ed919f 100644
> --- a/Documentation/driver-api/pps.rst
> +++ b/Documentation/driver-api/pps.rst
> @@ -202,6 +202,46 @@ Sometimes one needs to be able not only to catch PPS signals but to produce
> them also. For example, running a distributed simulation, which requires
> computers' clock to be synchronized very tightly.
>
> +To do so the class pps-gen has been added. PPS generators can be
> +registered in the kernel by defining a struct pps_gen_source_info as
> +follows::
> +
> + static struct pps_gen_source_info pps_gen_dummy_info = {
> + .name = "dummy",
> + .use_system_clock = true,
> + .get_time = pps_gen_dummy_get_time,
> + .enable = pps_gen_dummy_enable,
> + };
> +
> +Where the use_system_clock states if the generator uses the system
> +clock to generate its pulses, or from a peripheral device
or they are from a peripheral device
> +clock. Method get_time() is used to query the time stored into the
> +generator clock, while the method enable() is used to enable or
> +disable the PPS pulse generation.
> +
> +Then calling the function pps_gen_register_source() in your
> +initialization routine as follows creates a new generator in the
> +system::
> +
> + pps_gen = pps_gen_register_source(&pps_gen_dummy_info);
> +
> +Generators SYSFS support
> +------------------------
> +
> +If the SYSFS filesystem is enabled in the kernel it provides a new class::
> +
> + $ ls /sys/class/pps-gen/
> + pps-gen0/ pps-gen1/ pps-gen2/
> +
> +Every directory is the ID of a PPS generator defined in the system and
> +inside you find several files::
> +
> + $ ls -F /sys/class/pps-gen/pps-gen0/
> + dev enable name power/ subsystem@ system time uevent
> +
> +To enable the PPS signal generation you can use the command below::
> +
> + $ echo 1 > /sys/class/pps-gen/pps-gen0/enable
>
> Parallel port generator
> ------------------------
--
~Randy
