From 9d2cb8e8e6a3650613eab95c1b30023e81beb15c Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Fri, 7 Oct 2011 13:53:50 +0000 Subject: Add generic gpio.h in asm-generic 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 --- include/asm-generic/gpio.h | 74 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 include/asm-generic/gpio.h (limited to 'include') diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h new file mode 100644 index 0000000000..a1ebb28aec --- /dev/null +++ b/include/asm-generic/gpio.h @@ -0,0 +1,74 @@ +/* + * 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); -- cgit v1.2.1