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* pps: claim parallel port exclusivelyAlexander Gordeev2011-01-261-1/+1
| | | | | | | | | | | | | 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: Alexander Gordeev <lasaine@lvk.cs.msu.su> Cc: Alexander Gordeev <lasaine@lvk.cs.msu.su> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pps: add parallel port PPS clientAlexander Gordeev2011-01-131-0/+258
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: Alexander Gordeev <lasaine@lvk.cs.msu.su> Acked-by: Rodolfo Giometti <giometti@linux.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>