[4.4.y,23/52] dt-bindings: gpio: Add a gpio-reserved-ranges property

Commit Message

Fabrizio Castro May 13, 2019, 3:36 p.m. UTC

From: Stephen Boyd <[e-mail]>

commit b9c725ed73b7cecc7c9bc4b752ab3eb975ef9330 upstream.

Some qcom platforms make some GPIOs or pins unavailable for use
by non-secure operating systems, and thus reading or writing the
registers for those pins will cause access control issues.
Introduce a DT property to describe the set of GPIOs that are
available for use so that higher level OSes are able to know what
pins to avoid reading/writing.

Cc: Grant Likely <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Tested-by: Timur Tabi <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>
Signed-off-by: Fabrizio Castro <[e-mail]>
---
 Documentation/devicetree/bindings/gpio/gpio.txt | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Patch

diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt
index 069cdf6..6550775 100644
--- a/Documentation/devicetree/bindings/gpio/gpio.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio.txt
@@ -141,9 +141,9 @@  in a lot of designs, some using all 32 bits, some using 18 and some using
 first 18 GPIOs, at local offset 0 .. 17, are in use.
 
 If these GPIOs do not happen to be the first N GPIOs at offset 0...N-1, an
-additional bitmask is needed to specify which GPIOs are actually in use,
-and which are dummies. The bindings for this case has not yet been
-specified, but should be specified if/when such hardware appears.
+additional set of tuples is needed to specify which GPIOs are unusable, with
+the gpio-reserved-ranges binding. This property indicates the start and size
+of the GPIOs that can't be used.
 
 Example:
 
@@ -153,6 +153,7 @@  gpio-controller@00000000 {
 	gpio-controller;
 	#gpio-cells = <2>;
 	ngpios = <18>;
+	gpio-reserved-ranges = <0 4>, <12 2>;
 }
 
 The GPIO chip may contain GPIO hog definitions. GPIO hogging is a mechanism