docs: pps.txt: convert to ReST and rename to pps.rst

This file is already in a good shape: just its title and
adding some literal block markups is needed for it to be
part of the document.

While it has a small chapter with sysfs stuff, most of
the document is focused on driver development.

As it describes a kernel API, move it to the driver-api
directory.

In order to avoid conflicts, let's add an :orphan: tag
to it, to be removed when added to the driver-api book.

Signed-off-by: Mauro Carvalho Chehab <[e-mail]>
Acked-by: Rodolfo Giometti <[e-mail]>
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/pps/pps.txt Documentation/driver-api/pps.rst

···
+:orphan:
 
-			PPS - Pulse Per Second
-			----------------------
+======================
+PPS - Pulse Per Second
+======================
 
-(C) Copyright 2007 Rodolfo Giometti <[e-mail]>
+Copyright (C) 2007 Rodolfo Giometti <[e-mail]>
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
···
 --------------
 
 To register a PPS source into the kernel you should define a struct
-pps_source_info as follows:
+pps_source_info as follows::
 
     static struct pps_source_info pps_ktimer_info = {
 	    .name         = "ktimer",
···
     };
 
 and then calling the function pps_register_source() in your
-initialization routine as follows:
+initialization routine as follows::
 
     source = pps_register_source(&pps_ktimer_info,
 			PPS_CAPTUREASSERT | PPS_OFFSETASSERT);
 
-The pps_register_source() prototype is:
+The pps_register_source() prototype is::
 
   int pps_register_source(struct pps_source_info *info, int default_params)
 
···
 
 Once you have registered a new PPS source into the system you can
 signal an assert event (for example in the interrupt handler routine)
-just using:
+just using::
 
     pps_event(source, &ts, PPS_CAPTUREASSERT, ptr)
 
···
 SYSFS support
 -------------
 
-If the SYSFS filesystem is enabled in the kernel it provides a new class:
+If the SYSFS filesystem is enabled in the kernel it provides a new class::
 
    $ ls /sys/class/pps/
    pps0/  pps1/  pps2/
 
 Every directory is the ID of a PPS sources defined in the system and
-inside you find several files:
+inside you find several files::
 
    $ ls -F /sys/class/pps/pps0/
    assert     dev        mode       path       subsystem@
···
 
 
 Inside each "assert" and "clear" file you can find the timestamp and a
-sequence number:
+sequence number::
 
    $ cat /sys/class/pps/pps0/assert
    1170026870.983207967#8
···
 http://linuxpps.org , or https://github.com/redlab-i/pps-tools.
 
 Once you have enabled the compilation of pps-ktimer just modprobe it (if
-not statically compiled):
+not statically compiled)::
 
    # modprobe pps-ktimer
 
-and the run ppstest as follow:
+and the run ppstest as follow::
 
    $ ./ppstest /dev/pps1
    trying PPS source "/dev/pps1"
···
 computers (master) and PPS clients on others (slaves), and use very simple
 cables to deliver signals using parallel ports, for example.
 
-Parallel port cable pinout:
-pin	name	master      slave
-1	STROBE	  *------     *
-2	D0	  *     |     *
-3	D1	  *     |     *
-4	D2	  *     |     *
-5	D3	  *     |     *
-6	D4	  *     |     *
-7	D5	  *     |     *
-8	D6	  *     |     *
-9	D7	  *     |     *
-10	ACK	  *     ------*
-11	BUSY	  *           *
-12	PE	  *           *
-13	SEL	  *           *
-14	AUTOFD	  *           *
-15	ERROR	  *           *
-16	INIT	  *           *
-17	SELIN	  *           *
-18-25	GND	  *-----------*
+Parallel port cable pinout::
+
+	pin	name	master      slave
+	1	STROBE	  *------     *
+	2	D0	  *     |     *
+	3	D1	  *     |     *
+	4	D2	  *     |     *
+	5	D3	  *     |     *
+	6	D4	  *     |     *
+	7	D5	  *     |     *
+	8	D6	  *     |     *
+	9	D7	  *     |     *
+	10	ACK	  *     ------*
+	11	BUSY	  *           *
+	12	PE	  *           *
+	13	SEL	  *           *
+	14	AUTOFD	  *           *
+	15	ERROR	  *           *
+	16	INIT	  *           *
+	17	SELIN	  *           *
+	18-25	GND	  *-----------*
 
 Please note that parallel port interrupt occurs only on high->low transition,
 so it is used for PPS assert edge. PPS clear edge can be determined only

MAINTAINERS

···
 W:	http://wiki.enneenne.com/index.php/LinuxPPS_support
 L:	[e-mail] (subscribers-only)
 S:	Maintained
-F:	Documentation/pps/
+F:	Documentation/driver-api/pps.rst
 F:	Documentation/devicetree/bindings/pps/pps-gpio.txt
 F:	Documentation/ABI/testing/sysfs-pps
 F:	drivers/pps/