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 <mchehab+samsung@kernel.org> Acked-by: Rodolfo Giometti <giometti@enneenne.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Mauro Carvalho Chehab
Jonathan Corbet
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28aedd7ee2
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@ -1,8 +1,10 @@
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:orphan:
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PPS - Pulse Per Second
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----------------------
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======================
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PPS - Pulse Per Second
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======================
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(C) Copyright 2007 Rodolfo Giometti <giometti@enneenne.com>
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Copyright (C) 2007 Rodolfo Giometti <giometti@enneenne.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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@ -88,7 +90,7 @@ Coding example
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--------------
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To register a PPS source into the kernel you should define a struct
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pps_source_info as follows:
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pps_source_info as follows::
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static struct pps_source_info pps_ktimer_info = {
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.name = "ktimer",
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@ -101,12 +103,12 @@ pps_source_info as follows:
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};
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and then calling the function pps_register_source() in your
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initialization routine as follows:
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initialization routine as follows::
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source = pps_register_source(&pps_ktimer_info,
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PPS_CAPTUREASSERT | PPS_OFFSETASSERT);
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The pps_register_source() prototype is:
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The pps_register_source() prototype is::
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int pps_register_source(struct pps_source_info *info, int default_params)
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@ -118,7 +120,7 @@ pps_source_info which describe the capabilities of the driver).
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Once you have registered a new PPS source into the system you can
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signal an assert event (for example in the interrupt handler routine)
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just using:
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just using::
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pps_event(source, &ts, PPS_CAPTUREASSERT, ptr)
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@ -134,13 +136,13 @@ Please see the file drivers/pps/clients/pps-ktimer.c for example code.
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SYSFS support
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-------------
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If the SYSFS filesystem is enabled in the kernel it provides a new class:
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If the SYSFS filesystem is enabled in the kernel it provides a new class::
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$ ls /sys/class/pps/
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pps0/ pps1/ pps2/
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Every directory is the ID of a PPS sources defined in the system and
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inside you find several files:
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inside you find several files::
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$ ls -F /sys/class/pps/pps0/
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assert dev mode path subsystem@
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@ -148,7 +150,7 @@ inside you find several files:
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Inside each "assert" and "clear" file you can find the timestamp and a
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sequence number:
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sequence number::
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$ cat /sys/class/pps/pps0/assert
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1170026870.983207967#8
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@ -175,11 +177,11 @@ and the userland tools available in your distribution's pps-tools package,
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http://linuxpps.org , or https://github.com/redlab-i/pps-tools.
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Once you have enabled the compilation of pps-ktimer just modprobe it (if
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not statically compiled):
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not statically compiled)::
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# modprobe pps-ktimer
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and the run ppstest as follow:
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and the run ppstest as follow::
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$ ./ppstest /dev/pps1
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trying PPS source "/dev/pps1"
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@ -204,26 +206,27 @@ nor affordable. The cheap way is to load a PPS generator on one of the
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computers (master) and PPS clients on others (slaves), and use very simple
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cables to deliver signals using parallel ports, for example.
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Parallel port cable pinout:
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pin name master slave
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1 STROBE *------ *
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2 D0 * | *
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3 D1 * | *
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4 D2 * | *
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5 D3 * | *
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6 D4 * | *
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7 D5 * | *
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8 D6 * | *
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9 D7 * | *
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10 ACK * ------*
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11 BUSY * *
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12 PE * *
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13 SEL * *
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14 AUTOFD * *
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15 ERROR * *
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16 INIT * *
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17 SELIN * *
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18-25 GND *-----------*
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Parallel port cable pinout::
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pin name master slave
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1 STROBE *------ *
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2 D0 * | *
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3 D1 * | *
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4 D2 * | *
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5 D3 * | *
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6 D4 * | *
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7 D5 * | *
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8 D6 * | *
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9 D7 * | *
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10 ACK * ------*
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11 BUSY * *
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12 PE * *
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13 SEL * *
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14 AUTOFD * *
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15 ERROR * *
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16 INIT * *
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17 SELIN * *
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18-25 GND *-----------*
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Please note that parallel port interrupt occurs only on high->low transition,
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so it is used for PPS assert edge. PPS clear edge can be determined only
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@ -12659,7 +12659,7 @@ M: Rodolfo Giometti <giometti@enneenne.com>
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W: http://wiki.enneenne.com/index.php/LinuxPPS_support
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L: linuxpps@ml.enneenne.com (subscribers-only)
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S: Maintained
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F: Documentation/pps/
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F: Documentation/driver-api/pps.rst
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F: Documentation/devicetree/bindings/pps/pps-gpio.txt
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F: Documentation/ABI/testing/sysfs-pps
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F: drivers/pps/
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