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Add generic gpio.h in asm-generic

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Since we want want to have a standard GPIO interface, this adds a definition
for this into include/asm-generic/gpio.h.

Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass 2011-10-07 13:53:50 +00:00 • committed by Wolfgang Denk
parent 4750884306
commit 9d2cb8e8e6
1 changed files with 74 additions and 0 deletions
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/*
* Copyright (c) 2011 The Chromium OS Authors.
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
/*
* Generic GPIO API for U-Boot
*
* GPIOs are numbered from 0 to GPIO_COUNT-1 which value is defined
* by the SOC/architecture.
*
* Each GPIO can be an input or output. If an input then its value can
* be read as 0 or 1. If an output then its value can be set to 0 or 1.
* If you try to write an input then the value is undefined. If you try
* to read an output, barring something very unusual, you will get
* back the value of the output that you previously set.
*
* In some cases the operation may fail, for example if the GPIO number
* is out of range, or the GPIO is not available because its pin is
* being used by another function. In that case, functions may return
* an error value of -1.
*/
/**
* Make a GPIO an input.
*
* @param gp GPIO number
* @return 0 if ok, -1 on error
*/
int gpio_direction_input(int gp);
/**
* Make a GPIO an output, and set its value.
*
* @param gp GPIO number
* @param value GPIO value (0 for low or 1 for high)
* @return 0 if ok, -1 on error
*/
int gpio_direction_output(int gp, int value);
/**
* Get a GPIO's value. This will work whether the GPIO is an input
* or an output.
*
* @param gp GPIO number
* @return 0 if low, 1 if high, -1 on error
*/
int gpio_get_value(int gp);
/**
* Set an output GPIO's value. The GPIO must already be an output of
* this function may have no effect.
*
* @param gp GPIO number
* @param value GPIO value (0 for low or 1 for high)
* @return 0 if ok, -1 on error
*/
int gpio_set_value(int gp, int value);