Re: SPI devices and OF

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

>  From explicitly board code like we do today.  I mean the mechanism  
> can very so greatly that trying to decided and come up with all  
> possible cases and somehow encoding that in the device tree isn't  
> worth the effort.  Additionally you'll still need code to handle the  
> actual chip select and I don't see how you make that generic at all.
> 
> A board designer could use I2C, GPIO, or something off an FPGA.  I  
> just dont see trying to 'encode' this in the device tree as providing  
> any real value.

Or board designers can use board specific device-tree bits and board
specific code to udnerstand them :-) That works too and can be handy if
you have for example several versions of a board with small differences
that you want to expose that way in the device-tree.

That is, the devive-tree -can- be used to put proprietary stuff, though
if you do so, you should try to use prefixes on your properties, like
mycompany,xxxx

Ben.