of_spi: add generic binding support to specify cs gpio
authorJean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Thu, 15 Nov 2012 19:19:57 +0000 (20:19 +0100)
committerGrant Likely <grant.likely@secretlab.ca>
Wed, 21 Nov 2012 23:25:33 +0000 (23:25 +0000)
commit743179849015dc71bb2ea63d8cd4bfa7fdfb4bc6
treedcf0d554dd907740a5f4519355d4e896a94efd3b
parent15d0983f5cc862facc8453a592220598a36d7f9d
of_spi: add generic binding support to specify cs gpio

This will allow to use gpio for chip select with no modification in the
driver binding

When use the cs-gpios, the gpio number will be passed via the cs_gpio field
and the number of chip select will automatically increased with max(hw cs, gpio cs).

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

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: spi-devel-general@lists.sourceforge.net
Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
[grant.likely: fixed up type of cs count so min() can do type checking]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Documentation/devicetree/bindings/spi/spi-bus.txt
drivers/spi/spi.c
include/linux/spi/spi.h