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Simon Glass9d2cb8e2011-10-07 13:53:50 +00001/*
2 * Copyright (c) 2011 The Chromium OS Authors.
Joe Hershberger5f533ae2011-11-11 15:55:35 -06003 * Copyright (c) 2011, NVIDIA Corp. All rights reserved.
Wolfgang Denk1a459662013-07-08 09:37:19 +02004 * SPDX-License-Identifier: GPL-2.0+
Simon Glass9d2cb8e2011-10-07 13:53:50 +00005 */
6
Joe Hershberger5f533ae2011-11-11 15:55:35 -06007#ifndef _ASM_GENERIC_GPIO_H_
8#define _ASM_GENERIC_GPIO_H_
9
Simon Glass9d2cb8e2011-10-07 13:53:50 +000010/*
11 * Generic GPIO API for U-Boot
12 *
13 * GPIOs are numbered from 0 to GPIO_COUNT-1 which value is defined
14 * by the SOC/architecture.
15 *
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.
21 *
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.
26 */
27
28/**
Nikita Kiryanov94740e42012-11-26 23:06:32 +000029 * Request a gpio. This should be called before any of the other functions
30 * are used on this gpio.
Simon Glass9d2cb8e2011-10-07 13:53:50 +000031 *
Nikita Kiryanov94740e42012-11-26 23:06:32 +000032 * @param gp GPIO number
33 * @param label User label for this GPIO
Simon Glass9d2cb8e2011-10-07 13:53:50 +000034 * @return 0 if ok, -1 on error
35 */
Joe Hershberger5f533ae2011-11-11 15:55:35 -060036int gpio_request(unsigned gpio, const char *label);
37
38/**
39 * Stop using the GPIO. This function should not alter pin configuration.
40 *
41 * @param gpio GPIO number
42 * @return 0 if ok, -1 on error
43 */
44int gpio_free(unsigned gpio);
45
46/**
47 * Make a GPIO an input.
48 *
49 * @param gpio GPIO number
50 * @return 0 if ok, -1 on error
51 */
52int gpio_direction_input(unsigned gpio);
Simon Glass9d2cb8e2011-10-07 13:53:50 +000053
54/**
55 * Make a GPIO an output, and set its value.
56 *
Joe Hershberger5f533ae2011-11-11 15:55:35 -060057 * @param gpio GPIO number
Simon Glass9d2cb8e2011-10-07 13:53:50 +000058 * @param value GPIO value (0 for low or 1 for high)
59 * @return 0 if ok, -1 on error
60 */
Joe Hershberger5f533ae2011-11-11 15:55:35 -060061int gpio_direction_output(unsigned gpio, int value);
Simon Glass9d2cb8e2011-10-07 13:53:50 +000062
63/**
64 * Get a GPIO's value. This will work whether the GPIO is an input
65 * or an output.
66 *
Joe Hershberger5f533ae2011-11-11 15:55:35 -060067 * @param gpio GPIO number
Simon Glass9d2cb8e2011-10-07 13:53:50 +000068 * @return 0 if low, 1 if high, -1 on error
69 */
Joe Hershberger5f533ae2011-11-11 15:55:35 -060070int gpio_get_value(unsigned gpio);
Simon Glass9d2cb8e2011-10-07 13:53:50 +000071
72/**
Joe Hershberger5f533ae2011-11-11 15:55:35 -060073 * Set an output GPIO's value. The GPIO must already be an output or
Simon Glass9d2cb8e2011-10-07 13:53:50 +000074 * this function may have no effect.
75 *
Joe Hershberger5f533ae2011-11-11 15:55:35 -060076 * @param gpio GPIO number
Simon Glass9d2cb8e2011-10-07 13:53:50 +000077 * @param value GPIO value (0 for low or 1 for high)
78 * @return 0 if ok, -1 on error
79 */
Joe Hershberger5f533ae2011-11-11 15:55:35 -060080int gpio_set_value(unsigned gpio, int value);
Simon Glass96495d92014-02-26 15:59:24 -070081
82/* State of a GPIO, as reported by get_state() */
83enum {
84 GPIOF_INPUT = 0,
85 GPIOF_OUTPUT,
86 GPIOF_UNKNOWN,
87};
88
89struct device;
90
91/**
92 * struct struct dm_gpio_ops - Driver model GPIO operations
93 *
94 * Refer to functions above for description. These function largely copy
95 * the old API.
96 *
97 * This is trying to be close to Linux GPIO API. Once the U-Boot uses the
98 * new DM GPIO API, this should be really easy to flip over to the Linux
99 * GPIO API-alike interface.
100 *
101 * Akso it would be useful to standardise additional functions like
102 * pullup, slew rate and drive strength.
103 *
104 * gpio_request)( and gpio_free() are optional - if NULL then they will
105 * not be called.
106 *
107 * Note that @offset is the offset from the base GPIO of the device. So
108 * offset 0 is the device's first GPIO and offset o-1 is the last GPIO,
109 * where o is the number of GPIO lines controlled by the device. A device
110 * is typically used to control a single bank of GPIOs. Within complex
111 * SoCs there may be many banks and therefore many devices all referring
112 * to the different IO addresses within the SoC.
113 *
114 * The uclass combines all GPIO devices togther to provide a consistent
115 * numbering from 0 to n-1, where n is the number of GPIOs in total across
116 * all devices. Be careful not to confuse offset with gpio in the parameters.
117 */
118struct dm_gpio_ops {
119 int (*request)(struct device *dev, unsigned offset, const char *label);
120 int (*free)(struct device *dev, unsigned offset);
121 int (*direction_input)(struct device *dev, unsigned offset);
122 int (*direction_output)(struct device *dev, unsigned offset,
123 int value);
124 int (*get_value)(struct device *dev, unsigned offset);
125 int (*set_value)(struct device *dev, unsigned offset, int value);
126 int (*get_function)(struct device *dev, unsigned offset);
127 int (*get_state)(struct device *dev, unsigned offset, char *state,
128 int maxlen);
129};
130
131/**
132 * struct gpio_dev_priv - information about a device used by the uclass
133 *
134 * The uclass combines all active GPIO devices into a unified numbering
135 * scheme. To do this it maintains some private information aobut each
136 * device.
137 *
138 * To implement driver model support in your GPIO driver, add a probe
139 * handler, and set @gpio_count and @bank_name correctly in that handler.
140 * This tells the uclass the name of the GPIO bank and the number of GPIOs
141 * it contains.
142 *
143 * @bank_name: Name of the GPIO device (e.g 'a' means GPIOs will be called
144 * 'A0', 'A1', etc.
145 * @gpio_count: Number of GPIOs in this device
146 * @gpio_base: Base GPIO number for this device. For the first active device
147 * this will be 0; the numbering for others will follow sequentially so that
148 * @gpio_base for device 1 will equal the number of GPIOs in device 0.
149 */
150struct gpio_dev_priv {
151 const char *bank_name;
152 unsigned gpio_count;
153 unsigned gpio_base;
154};
155
156/* Access the GPIO operations for a device */
157#define gpio_get_ops(dev) ((struct dm_gpio_ops *)(dev)->driver->ops)
158
159/**
160 * gpio_get_bank_info - Return information about a GPIO bank/device
161 *
162 * This looks up a device and returns both its GPIO base name and the number
163 * of GPIOs it controls.
164 *
165 * @dev: Device to look up
166 * @offset_count: Returns number of GPIOs within this bank
167 * @return bank name of this device
168 */
169const char *gpio_get_bank_info(struct device *dev, int *offset_count);
170
171/**
172 * gpio_lookup_name - Look up a GPIO name and return its details
173 *
174 * This is used to convert a named GPIO into a device, offset and GPIO
175 * number.
176 *
177 * @name: GPIO name to look up
178 * @devp: Returns pointer to device which contains this GPIO
179 * @offsetp: Returns the offset number within this device
180 * @gpiop: Returns the absolute GPIO number, numbered from 0
181 */
182int gpio_lookup_name(const char *name, struct device **devp,
183 unsigned int *offsetp, unsigned int *gpiop);
184
Joe Hershberger5f533ae2011-11-11 15:55:35 -0600185#endif /* _ASM_GENERIC_GPIO_H_ */