On Tue, Feb 16, 2010 at 11:59 AM, Ernst Schwab <[email protected]> wrote: > Grant Likely <[email protected]> wrote: > >> Add a property to the /chosen node to assign short labels to devices. > > I'm not familiar with this and will check - does anyone know of an > existing example for this?
Oops, sorry. I meant the 'aliases' node. 'chosen' is for something else. Properties in the aliases node are simply name = "/path/to/node"; pairs. Do "grep -A 6 arch/powerpc/boot/dts/" to see lots of examples. dtc expands the <name> = &label; construct into the full path to the node. >> Unless you're trying to line up disparate data structure, the actually >> number assigned to a bus really doesn't matter. It is better to let >> Linux dynamically assign than to manually maintain the assigned bus >> numbers for each machine. Assuming dynamic assignment also protects >> against breaking userspace applications when, for whatever reason, the >> bus numbers get shuffled on a platform. > > Hm. What if we have two identical devices, lets say EEPROMs at25, > connected to two SPI controllers. These are set up as > /sys/bus/spi/devices/spi32766.0/eeprom and > /sys/bus/spi/devices/spi32765.0/eeprom. > How can userspace code determine which one it should > use if it needs to use the one connected to the first spi controller? > Can this be solved with the /chosen mechanism? Use the alias to find the spi bus you care about in /sys/devices/. Then whichever eeprom has that bus as its parent is the device you want. You can read the expanded device tree in /proc/device-tree. Unfortunately I don't have sample code that shows how to do this; I haven't had to do so personally yet. g. ------------------------------------------------------------------------------ SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev _______________________________________________ spi-devel-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/spi-devel-general
