This client driver allows you to use a GPIO pin as a source for PPS
signals.  Platform data [1] are used to specify the GPIO pin number,
label, assert event edge type, and whether clear events are captured.

This driver is based on the work by Ricardo Martins who submitted an
initial implementation [2] of a PPS IRQ client driver to the linuxpps
mailing-list on Dec 3 2010.

[1] include/linux/pps-gpio.h
[2] http://ml.enneenne.com/pipermail/linuxpps/2010-December/004155.html

[akpm@linux-foundation.org: remove unneeded cast of void*]
Signed-off-by: NJames Nuss <jamesnuss@nanometrics.ca>
Cc: Ricardo Martins <rasm@fe.up.pt>
Acked-by: NRodolfo Giometti <giometti@linux.it>
Signed-off-by: NRicardo Martins <rasm@fe.up.pt>
Cc: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Cc: Igor Plyatov <plyatov@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A default echo function has been provided so it is no longer an error when
you specify PPS_ECHOASSERT or PPS_ECHOCLEAR without an explicit echo
function.  This allows some code re-use and also makes it easier to write
client drivers since the default echo function does not normally need to
change.
Signed-off-by: NJames Nuss <jamesnuss@nanometrics.ca>
Reviewed-by: NBen Gardiner <bengardiner@nanometrics.ca>
Acked-by: NRodolfo Giometti <giometti@linux.it>
Cc: Ricardo Martins <rasm@fe.up.pt>
Cc: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Cc: Igor Plyatov <plyatov@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Replace EXTRA_CFLAGS with ccflags-y.
Signed-off-by: Nmatt mooney <mfm@muteddisk.com>
Acked-by: NWANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Both pps_parport and pps_gen_parport are written in a way that they
can't share a port with any other driver.  This can result in locking up
the process that loads modules or even the whole kernel if the modules
are compiled in.  Use PARPORT_FLAG_EXCL to indicate this.
Signed-off-by: NAlexander Gordeev <lasaine@lvk.cs.msu.su>
Cc: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NRodolfo Giometti <giometti@linux.it>
Reported-by: NIngo Molnar <mingo@elte.hu>
Cc: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add parallel port PPS client.  It uses a standard method for capturing
timestamps for assert edge transitions: getting a timestamp soon after an
interrupt has happened.

This is not a very precise source of time information due to interrupt
handling delays.  However, timestamps for clear edge transitions are much
more precise because the interrupt handler continuously polls hardware
port until the transition is done.

Hardware port operations require only about 1us so the maximum error
should not exceed this value.  This was my primary goal when developing
this client.

Clear edge capture could be disabled using clear_wait parameter.
Signed-off-by: NAlexander Gordeev <lasaine@lvk.cs.msu.su>
Acked-by: NRodolfo Giometti <giometti@linux.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove the code that gatheres timestamp in pps_tty_dcd_change() in case
passed ts parameter is NULL because it never happens in the current code.
Fix comments as well.
Signed-off-by: NAlexander Gordeev <lasaine@lvk.cs.msu.su>
Acked-by: NRodolfo Giometti <giometti@linux.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since we now have direct pointers to struct pps_device everywhere it's
easy to use dev_* functions to print messages instead of plain printks.
Where dev_* cannot be used printks are converted to pr_*.
Signed-off-by: NAlexander Gordeev <lasaine@lvk.cs.msu.su>
Acked-by: NRodolfo Giometti <giometti@linux.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Using device index as a pointer needs some unnecessary work to be done
every time the pointer is needed (in irq handler for example).  Using a
direct pointer is much more easy (and safe as well).
Signed-off-by: NAlexander Gordeev <lasaine@lvk.cs.msu.su>
Acked-by: NRodolfo Giometti <giometti@linux.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a helper function to gather timestamps.  This way clients don't have
to duplicate it.
Signed-off-by: NAlexander Gordeev <lasaine@lvk.cs.msu.su>
Acked-by: NRodolfo Giometti <giometti@linux.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Adds support, by using the PPS line discipline, for the PPS sources
connected with the CD (Carrier Detect) pin of a serial port.

[akpm@linux-foundation.org: fix cast size warnings]
Signed-off-by: NRodolfo Giometti <giometti@linux.it>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg KH <greg@kroah.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Each PPS source can be registered/deregistered into the system by using
special modules called "clients".  They simply define the PPS sources'
attributes and implement the time signal registration mechanism.

This patch adds a special directory for such clients and adds a dummy
client that can be useful to test system integrity on real systems.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NRodolfo Giometti <giometti@linux.it>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg KH <greg@kroah.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>