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 * Note: With driver model, the label is allocated so there is no need for
33 * the caller to preserve it.
35 * @param gp GPIO number
36 * @param label User label for this GPIO
37 * @return 0 if ok, -1 on error
39 int gpio_request(unsigned gpio, const char *label);
42 * Stop using the GPIO. This function should not alter pin configuration.
44 * @param gpio GPIO number
45 * @return 0 if ok, -1 on error
47 int gpio_free(unsigned gpio);
50 * Make a GPIO an input.
52 * @param gpio GPIO number
53 * @return 0 if ok, -1 on error
55 int gpio_direction_input(unsigned gpio);
58 * Make a GPIO an output, and set its value.
60 * @param gpio GPIO number
61 * @param value GPIO value (0 for low or 1 for high)
62 * @return 0 if ok, -1 on error
64 int gpio_direction_output(unsigned gpio, int value);
67 * Get a GPIO's value. This will work whether the GPIO is an input
70 * @param gpio GPIO number
71 * @return 0 if low, 1 if high, -1 on error
73 int gpio_get_value(unsigned gpio);
76 * Set an output GPIO's value. The GPIO must already be an output or
77 * this function may have no effect.
79 * @param gpio GPIO number
80 * @param value GPIO value (0 for low or 1 for high)
81 * @return 0 if ok, -1 on error
83 int gpio_set_value(unsigned gpio, int value);
85 /* State of a GPIO, as reported by get_function() */
89 GPIOF_UNUSED, /* Not claimed */
90 GPIOF_UNKNOWN, /* Not known */
91 GPIOF_FUNC, /* Not used as a GPIO */
99 * struct struct dm_gpio_ops - Driver model GPIO operations
101 * Refer to functions above for description. These function largely copy
104 * This is trying to be close to Linux GPIO API. Once the U-Boot uses the
105 * new DM GPIO API, this should be really easy to flip over to the Linux
106 * GPIO API-alike interface.
108 * Also it would be useful to standardise additional functions like
109 * pullup, slew rate and drive strength.
111 * gpio_request)( and gpio_free() are optional - if NULL then they will
114 * Note that @offset is the offset from the base GPIO of the device. So
115 * offset 0 is the device's first GPIO and offset o-1 is the last GPIO,
116 * where o is the number of GPIO lines controlled by the device. A device
117 * is typically used to control a single bank of GPIOs. Within complex
118 * SoCs there may be many banks and therefore many devices all referring
119 * to the different IO addresses within the SoC.
121 * The uclass combines all GPIO devices together to provide a consistent
122 * numbering from 0 to n-1, where n is the number of GPIOs in total across
123 * all devices. Be careful not to confuse offset with gpio in the parameters.
126 int (*request)(struct udevice *dev, unsigned offset, const char *label);
127 int (*free)(struct udevice *dev, unsigned offset);
128 int (*direction_input)(struct udevice *dev, unsigned offset);
129 int (*direction_output)(struct udevice *dev, unsigned offset,
131 int (*get_value)(struct udevice *dev, unsigned offset);
132 int (*set_value)(struct udevice *dev, unsigned offset, int value);
134 * get_function() Get the GPIO function
136 * @dev: Device to check
137 * @offset: GPIO offset within that device
138 * @return current function - GPIOF_...
140 int (*get_function)(struct udevice *dev, unsigned offset);
141 int (*get_state)(struct udevice *dev, unsigned offset, char *state,
146 * struct gpio_dev_priv - information about a device used by the uclass
148 * The uclass combines all active GPIO devices into a unified numbering
149 * scheme. To do this it maintains some private information about each
152 * To implement driver model support in your GPIO driver, add a probe
153 * handler, and set @gpio_count and @bank_name correctly in that handler.
154 * This tells the uclass the name of the GPIO bank and the number of GPIOs
157 * @bank_name: Name of the GPIO device (e.g 'a' means GPIOs will be called
159 * @gpio_count: Number of GPIOs in this device
160 * @gpio_base: Base GPIO number for this device. For the first active device
161 * this will be 0; the numbering for others will follow sequentially so that
162 * @gpio_base for device 1 will equal the number of GPIOs in device 0.
163 * @name: Array of pointers to the name for each GPIO in this bank. The
164 * value of the pointer will be NULL if the GPIO has not been claimed.
166 struct gpio_dev_priv {
167 const char *bank_name;
173 /* Access the GPIO operations for a device */
174 #define gpio_get_ops(dev) ((struct dm_gpio_ops *)(dev)->driver->ops)
177 * gpio_get_bank_info - Return information about a GPIO bank/device
179 * This looks up a device and returns both its GPIO base name and the number
180 * of GPIOs it controls.
182 * @dev: Device to look up
183 * @offset_count: Returns number of GPIOs within this bank
184 * @return bank name of this device
186 const char *gpio_get_bank_info(struct udevice *dev, int *offset_count);
189 * gpio_lookup_name - Look up a GPIO name and return its details
191 * This is used to convert a named GPIO into a device, offset and GPIO
194 * @name: GPIO name to look up
195 * @devp: Returns pointer to device which contains this GPIO
196 * @offsetp: Returns the offset number within this device
197 * @gpiop: Returns the absolute GPIO number, numbered from 0
199 int gpio_lookup_name(const char *name, struct udevice **devp,
200 unsigned int *offsetp, unsigned int *gpiop);
202 #endif /* _ASM_GENERIC_GPIO_H_ */