Messages in this thread | | | Date | Fri, 14 Aug 2009 10:01:34 +1000 | Subject | GPIOLIB, GPIO_SYS and port-wide accesses | From | John Williams <> |
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Hi,
As I see it the gpiolib and sysfs export insists on single bit accesses even on gpio pins that are located on the same physical device/port.
A couple of years ago there was mention of port-wide accesses being a good thing:
http://lkml.indiana.edu/hypermail/linux/kernel/0608.0/0731.html (towards the bottom)
Did anything ever come of that?
Per-bit access is pretty inflexible if you are driving a 7-segment display or 8-LED bar display, holding lots of file descriptors open etc, and lots of syscall overhead.
sysfs syntax like
$ echo "240-247" > export $ echo 255 > gpio240-247/direction (8-bit binary mask - output) $ echo 255 > gpio240-247/value (all ones)
would be reasonably friendly, obviously the underlying gpiolib would have to have some notion of coupled ports.
Any thoughts?
John -- John Williams, PetaLogix - Linux Solutions for a Reconfigurable World w: www.petalogix.com p: +61-7-30090663 f: +61-7-30090663
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