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