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dt-bindings: gpio: Add a gpio-reserved-ranges property 

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 <grant.likely@secretlab.ca>
Cc: <devicetree@vger.kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Tested-by: Timur Tabi <timur@codeaurora.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Stephen Boyd 2018-03-23 09:34:49 -07:00 committed by Linus Walleij
parent 0c8efd610b
commit b9c725ed73
1 changed files with 4 additions and 3 deletions
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7
Documentation/devicetree/bindings/gpio/gpio.txt
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@ -151,9 +151,9 @@ 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.
Optionally, a GPIO controller may have a "gpio-line-names" property. This is
an array of strings defining the names of the GPIO lines going out of the
@ -178,6 +178,7 @@ gpio-controller@00000000 {
gpio-controller;
#gpio-cells = <2>;
ngpios = <18>;
gpio-reserved-ranges = <0 4>, <12 2>;
gpio-line-names = "MMC-CD", "MMC-WP", "VDD eth", "RST eth", "LED R",
"LED G", "LED B", "Col A", "Col B", "Col C", "Col D",
"Row A", "Row B", "Row C", "Row D", "NMI button",