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.
29 * Request a gpio. This should be called before any of the other functions
30 * are used on this gpio.
32 * @param gp GPIO number
33 * @param label User label for this GPIO
34 * @return 0 if ok, -1 on error
36 int gpio_request(unsigned gpio, const char *label);
39 * Stop using the GPIO. This function should not alter pin configuration.
41 * @param gpio GPIO number
42 * @return 0 if ok, -1 on error
44 int gpio_free(unsigned gpio);
47 * Make a GPIO an input.
49 * @param gpio GPIO number
50 * @return 0 if ok, -1 on error
52 int gpio_direction_input(unsigned gpio);
55 * Make a GPIO an output, and set its value.
57 * @param gpio GPIO number
58 * @param value GPIO value (0 for low or 1 for high)
59 * @return 0 if ok, -1 on error
61 int gpio_direction_output(unsigned gpio, int value);
64 * Get a GPIO's value. This will work whether the GPIO is an input
67 * @param gpio GPIO number
68 * @return 0 if low, 1 if high, -1 on error
70 int gpio_get_value(unsigned gpio);
73 * Set an output GPIO's value. The GPIO must already be an output or
74 * this function may have no effect.
76 * @param gpio GPIO number
77 * @param value GPIO value (0 for low or 1 for high)
78 * @return 0 if ok, -1 on error
80 int gpio_set_value(unsigned gpio, int value);
82 /* State of a GPIO, as reported by get_function() */
86 GPIOF_UNUSED, /* Not claimed */
87 GPIOF_UNKNOWN, /* Not known */
88 GPIOF_FUNC, /* Not used as a GPIO */
96 * struct struct dm_gpio_ops - Driver model GPIO operations
98 * Refer to functions above for description. These function largely copy
101 * This is trying to be close to Linux GPIO API. Once the U-Boot uses the
102 * new DM GPIO API, this should be really easy to flip over to the Linux
103 * GPIO API-alike interface.
105 * Akso it would be useful to standardise additional functions like
106 * pullup, slew rate and drive strength.
108 * gpio_request)( and gpio_free() are optional - if NULL then they will
111 * Note that @offset is the offset from the base GPIO of the device. So
112 * offset 0 is the device's first GPIO and offset o-1 is the last GPIO,
113 * where o is the number of GPIO lines controlled by the device. A device
114 * is typically used to control a single bank of GPIOs. Within complex
115 * SoCs there may be many banks and therefore many devices all referring
116 * to the different IO addresses within the SoC.
118 * The uclass combines all GPIO devices togther to provide a consistent
119 * numbering from 0 to n-1, where n is the number of GPIOs in total across
120 * all devices. Be careful not to confuse offset with gpio in the parameters.
123 int (*request)(struct udevice *dev, unsigned offset, const char *label);
124 int (*free)(struct udevice *dev, unsigned offset);
125 int (*direction_input)(struct udevice *dev, unsigned offset);
126 int (*direction_output)(struct udevice *dev, unsigned offset,
128 int (*get_value)(struct udevice *dev, unsigned offset);
129 int (*set_value)(struct udevice *dev, unsigned offset, int value);
131 * get_function() Get the GPIO function
133 * @dev: Device to check
134 * @offset: GPIO offset within that device
135 * @return current function - GPIOF_...
137 int (*get_function)(struct udevice *dev, unsigned offset);
138 int (*get_state)(struct udevice *dev, unsigned offset, char *state,
143 * struct gpio_dev_priv - information about a device used by the uclass
145 * The uclass combines all active GPIO devices into a unified numbering
146 * scheme. To do this it maintains some private information aobut each
149 * To implement driver model support in your GPIO driver, add a probe
150 * handler, and set @gpio_count and @bank_name correctly in that handler.
151 * This tells the uclass the name of the GPIO bank and the number of GPIOs
154 * @bank_name: Name of the GPIO device (e.g 'a' means GPIOs will be called
156 * @gpio_count: Number of GPIOs in this device
157 * @gpio_base: Base GPIO number for this device. For the first active device
158 * this will be 0; the numbering for others will follow sequentially so that
159 * @gpio_base for device 1 will equal the number of GPIOs in device 0.
161 struct gpio_dev_priv {
162 const char *bank_name;
167 /* Access the GPIO operations for a device */
168 #define gpio_get_ops(dev) ((struct dm_gpio_ops *)(dev)->driver->ops)
171 * gpio_get_bank_info - Return information about a GPIO bank/device
173 * This looks up a device and returns both its GPIO base name and the number
174 * of GPIOs it controls.
176 * @dev: Device to look up
177 * @offset_count: Returns number of GPIOs within this bank
178 * @return bank name of this device
180 const char *gpio_get_bank_info(struct udevice *dev, int *offset_count);
183 * gpio_lookup_name - Look up a GPIO name and return its details
185 * This is used to convert a named GPIO into a device, offset and GPIO
188 * @name: GPIO name to look up
189 * @devp: Returns pointer to device which contains this GPIO
190 * @offsetp: Returns the offset number within this device
191 * @gpiop: Returns the absolute GPIO number, numbered from 0
193 int gpio_lookup_name(const char *name, struct udevice **devp,
194 unsigned int *offsetp, unsigned int *gpiop);
196 #endif /* _ASM_GENERIC_GPIO_H_ */