2 * Copyright (c) 2011 The Chromium OS Authors.
3 * Copyright (c) 2011, NVIDIA Corp. All rights reserved.
4 * SPDX-License-Identifier: GPL-2.0+
7 #ifndef _ASM_GENERIC_GPIO_H_
8 #define _ASM_GENERIC_GPIO_H_
11 * Generic GPIO API for U-Boot
13 * GPIOs are numbered from 0 to GPIO_COUNT-1 which value is defined
14 * by the SOC/architecture.
16 * Each GPIO can be an input or output. If an input then its value can
17 * be read as 0 or 1. If an output then its value can be set to 0 or 1.
18 * If you try to write an input then the value is undefined. If you try
19 * to read an output, barring something very unusual, you will get
20 * back the value of the output that you previously set.
22 * In some cases the operation may fail, for example if the GPIO number
23 * is out of range, or the GPIO is not available because its pin is
24 * being used by another function. In that case, functions may return
25 * an error value of -1.
30 GPIOF_OUTPUT_INIT_LOW,
31 GPIOF_OUTPUT_INIT_HIGH,
36 enum gpio_flags flags;
41 * Request a gpio. This should be called before any of the other functions
42 * are used on this gpio.
44 * @param gp GPIO number
45 * @param label User label for this GPIO
46 * @return 0 if ok, -1 on error
48 int gpio_request(unsigned gpio, const char *label);
51 * Stop using the GPIO. This function should not alter pin configuration.
53 * @param gpio GPIO number
54 * @return 0 if ok, -1 on error
56 int gpio_free(unsigned gpio);
59 * Make a GPIO an input.
61 * @param gpio GPIO number
62 * @return 0 if ok, -1 on error
64 int gpio_direction_input(unsigned gpio);
67 * Make a GPIO an output, and set its value.
69 * @param gpio GPIO number
70 * @param value GPIO value (0 for low or 1 for high)
71 * @return 0 if ok, -1 on error
73 int gpio_direction_output(unsigned gpio, int value);
76 * Get a GPIO's value. This will work whether the GPIO is an input
79 * @param gpio GPIO number
80 * @return 0 if low, 1 if high, -1 on error
82 int gpio_get_value(unsigned gpio);
85 * Set an output GPIO's value. The GPIO must already be an output or
86 * this function may have no effect.
88 * @param gpio GPIO number
89 * @param value GPIO value (0 for low or 1 for high)
90 * @return 0 if ok, -1 on error
92 int gpio_set_value(unsigned gpio, int value);
95 * Request a GPIO and configure it
96 * @param gpios pointer to array of gpio defs
97 * @param count number of GPIOs to set up
99 int gpio_request_one(unsigned gpio, enum gpio_flags flags, const char *label);
102 * Request a set of GPIOs and configure them
103 * @param gpios pointer to array of gpio defs
104 * @param count number of GPIOs to set up
106 int gpio_request_array(const struct gpio *gpios, int count);
109 * Release a set of GPIOs
110 * @param gpios pointer to array of gpio defs
111 * @param count number of GPIOs to set up
113 int gpio_free_array(const struct gpio *gpios, int count);
115 #endif /* _ASM_GENERIC_GPIO_H_ */