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linux-next/Documentation/devicetree
Dirk Behme 62f4666968 Input: zforce - make the interrupt GPIO optional
Add support for hardware which uses an I2C Serializer / Deserializer
(SerDes) to communicate with the zFroce touch driver. In this case the
SerDes will be configured as an interrupt controller and the zForce driver
will have no access to poll the GPIO line.

To support this, we add two dedicated new GPIOs in the device tree:
reset-gpios and irq-gpios, with the irq-gpios being optional.

To not break the existing device trees, the index based 'gpios' entries
are still supported, but marked as deprecated.

With this, if the interrupt GPIO is available, either via the old or new
device tree style, the while loop will read and handle the packets as long
as the GPIO indicates that the interrupt is asserted (existing, unchanged
driver behavior).

If the interrupt GPIO isn't available, i.e. not configured via the new
device tree style, we are falling back to one read per ISR invocation
(new behavior to support the SerDes).

Note that the gpiod functions help to handle the optional GPIO:
devm_gpiod_get_index_optional() will return NULL in case the interrupt
GPIO isn't available. And gpiod_get_value_cansleep() does cover this, too,
by returning 0 in this case.

Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@bq.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
2015-08-03 14:10:10 -07:00
..
bindings Input: zforce - make the interrupt GPIO optional 2015-08-03 14:10:10 -07:00
00-INDEX
booting-without-of.txt ARM: 8354/1: Documentation: devicetree: root node serial-number property documentation 2015-05-08 10:42:34 +01:00
changesets.txt
dynamic-resolution-notes.txt of: Introduce Device Tree resolve support. 2014-10-04 21:24:26 +01:00
of_unittest.txt Documentation: rename of_selftest.txt to of_unittest.txt 2015-03-25 00:50:53 -05:00
overlay-notes.txt Documentation: devicetree: Fix double words in Doumentation/devicetree 2015-01-28 15:13:11 -07:00
todo.txt of: Eliminate of_allnodes list 2014-11-04 13:29:38 +00:00
usage-model.txt