On Wednesday 30 November 2011 13:12:46 Frank Wille wrote: > Mike Frysinger wrote: > > the way the Linux GPIO sysfs interface works is: > > - by default, no pins are exported to userspace > > - to export a pin, you write the pin you want to request to the pseudo > > file "export" (this is what the gpio_export() func does) > > Ok, I understand. > What were the reasons against exporting all GPIO pins by default?
resource management. the act of exporting a pin reserves it for userspace, thus you may not reserve a pin that another device has already taken. > >> Under NetBSD (and OpenBSD) it is just a single file, /dev/gpio0, which > >> controls all GPIO pins of a device via ioctl(). > > > > sounds like we could still utilize the existing gpio driver ... we just > > replace the core concepts (requesting/releasing a pin, and changing its > > direction/value at runtime) with the NetBSD/OpenBSD ioctls > > That is certainly possible. But also setting a pin to 0 or 1 has to be done > via ioctl(). that's fine > > sounds like what we actually want to do is rip the current code out of > > the GPIO cable driver and into a GPIO core, and then add a GPIO parport > > lowlevel driver that uses this new core. > > Sounds good. If you prepare the GPIO code for Linux, I can add NetBSD > support and will write the parport lowlevel driver using it. i see what you did there ... tricking me into writing the gpio core ;) i'll post a patch soonish ... -mike
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