Maybe I misunderstand you, in my view it is the responsibility of <vendor>
   to create their DTS files to indicate they want <special-card1> to bind to
   generic-uio.

Device tree is a OS-neutral hardware description language. "generic-uio"
is neither OS-neutral nor a hardware description. devicetree.org has
more information about this.

   Our use-case is pretty clear, in FPGA-based systems it is common to create
   arbitrary devices that developers just want to control from userspace,
   with simple IRQ and IO capabilities (DMA can come later :). �They don't
   need to bind to other kernel APIs or subsystems, and don't want to invest
   in one-off kernel drivers that simply will never go upstream.

For that, the new_compatible-file would be suitable, I think.

   UIO is perfect, and simply tagging the device as generic-uio in the DTS is
   so simple, clean, and elegant.

Simple, yes (I do understand I wrote the first approach ;)) . Elegant,
not really, because it breaks core conventions of the device tree. For
your case it is a very conveniant hack, but it is still a hack.

Regards,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |