Tuomas Kulve <tuomas at kulve.fi> [2008-03-11 10:26:50]: > Petr Stetiar wrote: > > > Because 'gpsdriver' seems to be some kind of middleware between userspace > > applications and kernel driver. It powers On/Off the GPS, uploads also > > How does it power the GPS on/off? I.e. how do you ask it to do it? That's what I want to find out. I'm quite lost in strace's output, since there are some unknown syscalls used like SYS_284 and SYS_285, and I didn't find out what they're yet. I don't have the systrace's output here, but it's something like this - if for example 'navicore' want access to GPS, it write's somehow 'P 3\n' to gpsdriver and gpsdriver powers on GPS using GPS GPIO's in /sys (you can find them easily by using strings on gpsdriver binary), uploads nvd_data file, creates /dev/pts/X device and makes /dev/pgps symlink to it and then starts gpsd daemon using this /dev/pgps device. Then if 'navicore' don't want to use GPS device, so it writes 'P 0\n' to gpsdriver somehow and gpsdriver powers off the GPS device. -- ynezz
