On Wed, May 9, 2012 at 3:34 AM, Thomas Abraham
[off-list ref] wrote:

The set_level callback in the controller data, which is used to configure
the slave select line, cannot be supported when migrating the driver to
device tree based discovery. Since all the platforms currently use gpio
as the slave select line, this callback can be removed from the
controller data and replaced with call to gpio_set_value in the driver.

This patch is ok.
Separately, you might also want to see if we really need the air-tight
protection of spin_lock_irqsave around enable_cs - IIRC someone
had a CS coming out of an gpio extender connected over I2C