2 * Copyright (c) 2011 The Chromium OS Authors.
3 * Copyright (c) 2011, NVIDIA Corp. All rights reserved.
4 * See file CREDITS for list of people who contributed to this
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2 of
10 * the License, or (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
23 #ifndef _ASM_GENERIC_GPIO_H_
24 #define _ASM_GENERIC_GPIO_H_
27 * Generic GPIO API for U-Boot
29 * GPIOs are numbered from 0 to GPIO_COUNT-1 which value is defined
30 * by the SOC/architecture.
32 * Each GPIO can be an input or output. If an input then its value can
33 * be read as 0 or 1. If an output then its value can be set to 0 or 1.
34 * If you try to write an input then the value is undefined. If you try
35 * to read an output, barring something very unusual, you will get
36 * back the value of the output that you previously set.
38 * In some cases the operation may fail, for example if the GPIO number
39 * is out of range, or the GPIO is not available because its pin is
40 * being used by another function. In that case, functions may return
41 * an error value of -1.
46 GPIOF_OUTPUT_INIT_LOW,
47 GPIOF_OUTPUT_INIT_HIGH,
52 enum gpio_flags flags;
57 * Request a gpio. This should be called before any of the other functions
58 * are used on this gpio.
60 * @param gp GPIO number
61 * @param label User label for this GPIO
62 * @return 0 if ok, -1 on error
64 int gpio_request(unsigned gpio, const char *label);
67 * Stop using the GPIO. This function should not alter pin configuration.
69 * @param gpio GPIO number
70 * @return 0 if ok, -1 on error
72 int gpio_free(unsigned gpio);
75 * Make a GPIO an input.
77 * @param gpio GPIO number
78 * @return 0 if ok, -1 on error
80 int gpio_direction_input(unsigned gpio);
83 * Make a GPIO an output, and set its value.
85 * @param gpio GPIO number
86 * @param value GPIO value (0 for low or 1 for high)
87 * @return 0 if ok, -1 on error
89 int gpio_direction_output(unsigned gpio, int value);
92 * Get a GPIO's value. This will work whether the GPIO is an input
95 * @param gpio GPIO number
96 * @return 0 if low, 1 if high, -1 on error
98 int gpio_get_value(unsigned gpio);
101 * Set an output GPIO's value. The GPIO must already be an output or
102 * this function may have no effect.
104 * @param gpio GPIO number
105 * @param value GPIO value (0 for low or 1 for high)
106 * @return 0 if ok, -1 on error
108 int gpio_set_value(unsigned gpio, int value);
111 * Request a GPIO and configure it
112 * @param gpios pointer to array of gpio defs
113 * @param count number of GPIOs to set up
115 int gpio_request_one(unsigned gpio, enum gpio_flags flags, const char *label);
118 * Request a set of GPIOs and configure them
119 * @param gpios pointer to array of gpio defs
120 * @param count number of GPIOs to set up
122 int gpio_request_array(const struct gpio *gpios, int count);
125 * Release a set of GPIOs
126 * @param gpios pointer to array of gpio defs
127 * @param count number of GPIOs to set up
129 int gpio_free_array(const struct gpio *gpios, int count);
131 #endif /* _ASM_GENERIC_GPIO_H_ */