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gpio: add DT bindings for existing consumer flags

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It is customary for GPIO controllers to support open drain/collector
and open source/emitter configurations. Add standard GPIO line flags
to account for this and augment the documentation to say that these
are the most generic bindings.

Several people approached me to add new flags to the lines, and this
makes sense, but let's first bind up the most common cases before we
start to add exotic stuff.

Thanks to H. Nikolaus Schaller for ideas on how to encode single-ended
wiring such as open drain/source and open collector/emitter.

Cc: Tony Lindgren <tony@atomide.com>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Linus Walleij
2015-09-24 15:05:45 -07:00
parent b8664924e8
commit 69d301fdd1
2 changed files with 27 additions and 2 deletions
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12
include/dt-bindings/gpio/gpio.h
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@@ -9,7 +9,19 @@
#ifndef _DT_BINDINGS_GPIO_GPIO_H
#define _DT_BINDINGS_GPIO_GPIO_H
/* Bit 0 express polarity */
#define GPIO_ACTIVE_HIGH 0
#define GPIO_ACTIVE_LOW 1
/* Bit 1 express single-endedness */
#define GPIO_PUSH_PULL 0
#define GPIO_SINGLE_ENDED 2
/*
* Open Drain/Collector is the combination of single-ended active low,
* Open Source/Emitter is the combination of single-ended active high.
*/
#define GPIO_OPEN_DRAIN (GPIO_SINGLE_ENDED | GPIO_ACTIVE_LOW)
#define GPIO_OPEN_SOURCE (GPIO_SINGLE_ENDED | GPIO_ACTIVE_HIGH)
#endif