gpiopps(4) - NetBSD Manual Pages

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GPIOPPS(4)              NetBSD Kernel Interfaces Manual             GPIOPPS(4)


NAME

     gpiopps -- install a PPS handler on GPIO pins


SYNOPSIS

     gpiopps* at gpio? offset 0 mask 0x1 flag 0x0


DESCRIPTION

     The gpiopps driver provides a 1PPS handler using the PPSAPI on one or two
     GPIO pins.

     The base pin number is specified in the kernel configuration file with
     the offset locator.  The mask should have 1 or 2 bits set, indicating
     which pins offset from the base pin should be used (0 .. 31).  Pin con-
     figurations are discussed below.

     The flag locator modifies the pin configuration:

     0x01      The PPS ASSERT signal should be triggered on the negative
               (falling) edge of the assert pin.  The default is to trigger on
               the positive (rising) edge of the pin.

     0x02      By default, gpiopps will use double-edge triggering when only a
               single pin is specified and the underlying GPIO hardware sup-
               ports it.  This flag disables the use of double-edge trigger-
               ing.

     If a single pin is specified, gpiopps uses double-edge triggering to sup-
     port ASSERT and CLEAR PPS signals.  If the underlying GPIO hardware does
     not support double-edge triggering, or if this feature is diabled in the
     flag locator, then only ASSERT will be signaled on the specified edge.

     If two pins are specified, the first pin is used to trigger the ASSERT
     signal and the second pin is used to trigger the CLEAR signal.  The
     ASSERT pin's trigger edge is specified by by the flag locator, and the
     CLEAR pin triggers on the opposite edge.  This allows ASSERT and CLEAR
     signals to be triggered even if the underlying GPIO hardware does not
     support double-edge triggering.  In this scenario, both GPIO pins would
     be connected in parallel to the device sending the 1PPS signals.

     The offset, mask, and flag locators can also be specified when gpiopps is
     attached at runtime using the GPIOATTACH ioctl(2) on the gpio(4) device.


SEE ALSO

     gpio(4), drvctl(8), gpioctl(8)


HISTORY

     The gpiopps driver first appeared in NetBSD 9.0.


AUTHORS

     The gpiopps driver was written by Brad Spencer <brad@anduin.eldar.org>.

NetBSD 10.1                      May 11, 2018                      NetBSD 10.1