On 06/10/2015 09:04 AM, Ludovic Desroches wrote:

Using a string to describe a pin in the device tree can be not enough.
Some controllers may need extra information to fully describe a pin. It
concerns mainly controllers which have a per pin muxing approach which
don't fit well the notions of groups and functions.
Instead of using a pin name, a 32 bit value is used. The 16 least
significant bits are used for the pin number. Other 16 bits can be used to
store extra parameters.

The driver for the pin controller is supposed to provide this 
information in a table. The whole point of having a driver, rather than 
a table/list of raw register values in the DT, is so the driver can 
provide this information at a semantic level. This information is fixed 
per SoC and so make sense to put into a driver, while the board-specific 
configuration varies wildly, and hence makes sense to put into DT.