Following discussions last months on this mailing list about how bad it is to use /dev/mem and mapping it with mmap to access the hardware memory (and I totally agree on this!), I am trying to rewrite for NetBSD a piece of hack written for GNU/Linux distros on the RaspberryPi.
The goal of the project is to turn the RaspberryPi into an FM transmitter (http://www.icrobotics.co.uk/wiki/index.php/Turning_the_Raspberry_Pi_Into_an_FM_Transmitter
). As a beginner on NetBSD platforms, I am happy I could familiarize myself with the ioctl calls and the gpio (4) kernel interface. I am now able to query the number of active pins on the GPIO, read their current status and set them to High or Low values. But the aforementioned hack necessitates to be able to write to some GPIO registers controlling the GPIO clocks, to modulate clock signals that we can then output to some GPIO pins.
I've gone through the gpio and gpioctl code, and I thank Jared and Marc for their work, but I couldn't see how to do that... Any clue?