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@enneenne.com>
---
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..c71b3b878e41 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 int 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
+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 a new generator is created into 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
------------------------
--
2.34.1On Tue, Oct 08, 2024 at 03:50:32PM +0200, 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@enneenne.com> > --- > Documentation/driver-api/pps.rst | 40 ++++++++++++++++++++++++++++++++ All of this can go into the .c file and autogenerated there, no need for a separate .rst file that will quickly get out-of-date. thanks, greg k-h
On 08/10/24 17:43, Greg KH wrote: > On Tue, Oct 08, 2024 at 03:50:32PM +0200, 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@enneenne.com> >> --- >> Documentation/driver-api/pps.rst | 40 ++++++++++++++++++++++++++++++++ > > All of this can go into the .c file and autogenerated there, no need for > a separate .rst file that will quickly get out-of-date. I see. I'm going to add proper documentation within .c files. But since some references about PPS generators are also present in this file, I think it would be wise to add some notes about the new interface... Ciao, Rodolfo -- GNU/Linux Solutions e-mail: giometti@enneenne.com Linux Device Driver giometti@linux.it Embedded Systems phone: +39 349 2432127 UNIX programming
On Wed, Oct 09, 2024 at 10:48:18AM +0200, Rodolfo Giometti wrote: > On 08/10/24 17:43, Greg KH wrote: > > On Tue, Oct 08, 2024 at 03:50:32PM +0200, 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@enneenne.com> > > > --- > > > Documentation/driver-api/pps.rst | 40 ++++++++++++++++++++++++++++++++ > > > > All of this can go into the .c file and autogenerated there, no need for > > a separate .rst file that will quickly get out-of-date. > > I see. I'm going to add proper documentation within .c files. But since some > references about PPS generators are also present in this file, I think it > would be wise to add some notes about the new interface... Why not just move all of the documentation into the .c files? thanks, greg k-h
On 09/10/24 11:14, Greg KH wrote: > On Wed, Oct 09, 2024 at 10:48:18AM +0200, Rodolfo Giometti wrote: >> On 08/10/24 17:43, Greg KH wrote: >>> On Tue, Oct 08, 2024 at 03:50:32PM +0200, 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@enneenne.com> >>>> --- >>>> Documentation/driver-api/pps.rst | 40 ++++++++++++++++++++++++++++++++ >>> >>> All of this can go into the .c file and autogenerated there, no need for >>> a separate .rst file that will quickly get out-of-date. >> >> I see. I'm going to add proper documentation within .c files. But since some >> references about PPS generators are also present in this file, I think it >> would be wise to add some notes about the new interface... > > Why not just move all of the documentation into the .c files? I see, but this is another story. :-P At the moment I prefer to just add a note here about the new interface, and later we can do what you suggest. Ciao, Rodolfo -- GNU/Linux Solutions e-mail: giometti@enneenne.com Linux Device Driver giometti@linux.it Embedded Systems phone: +39 349 2432127 UNIX programming
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