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a10203c691
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>
33 lines
807 B
Plaintext
33 lines
807 B
Plaintext
#
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# PPS clients configuration
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#
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if PPS
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comment "PPS clients support"
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config PPS_CLIENT_KTIMER
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tristate "Kernel timer client (Testing client, use for debug)"
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help
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If you say yes here you get support for a PPS debugging client
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which uses a kernel timer to generate the PPS signal.
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This driver can also be built as a module. If so, the module
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will be called pps-ktimer.
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config PPS_CLIENT_LDISC
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tristate "PPS line discipline"
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depends on PPS
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help
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If you say yes here you get support for a PPS source connected
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with the CD (Carrier Detect) pin of your serial port.
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config PPS_CLIENT_PARPORT
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tristate "Parallel port PPS client"
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depends on PPS && PARPORT
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help
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If you say yes here you get support for a PPS source connected
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with the interrupt pin of your parallel port.
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endif
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