The device tree has a way to specify GPIO lines as chip selects. From
the binding docs:
So if for example the controller has 2 CS lines, and the cs-gpios
property looks like this:
cs-gpios = <&gpio1 0 0> <0> <&gpio1 1 0> <&gpio1 2 0>;
Then it should be configured so that num_chipselect = 4 with the
following mapping:
cs0 : &gpio1 0 0
cs1 : native
cs2 : &gpio1 1 0
cs3 : &gpio1 2 0
Add support for this, while retaining backward-compatibility with
existing device trees; the driver will preserve existing behavior if a
cs-gpios list is not given, or if a particular line is specified as <0>
(native).
This implementation is inspired by similar implementations in
neighboring drivers for other platforms: atmega, mxc, etc.
Signed-off-by: George Hilliard <ghilliar@amazon.com>
Reviewed-by: Stefan Roese <sr@denx.de>
2df286390a