1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
/*
* Copyright (c) 2011 The Chromium OS Authors.
* Copyright (c) 2011, NVIDIA Corp. All rights reserved.
* SPDX-License-Identifier: GPL-2.0+
*/
#ifndef _ASM_GENERIC_GPIO_H_
#define _ASM_GENERIC_GPIO_H_
/*
* Generic GPIO API for U-Boot
*
* GPIOs are numbered from 0 to GPIO_COUNT-1 which value is defined
* by the SOC/architecture.
*
* Each GPIO can be an input or output. If an input then its value can
* be read as 0 or 1. If an output then its value can be set to 0 or 1.
* If you try to write an input then the value is undefined. If you try
* to read an output, barring something very unusual, you will get
* back the value of the output that you previously set.
*
* In some cases the operation may fail, for example if the GPIO number
* is out of range, or the GPIO is not available because its pin is
* being used by another function. In that case, functions may return
* an error value of -1.
*/
/**
* Request a gpio. This should be called before any of the other functions
* are used on this gpio.
*
* @param gp GPIO number
* @param label User label for this GPIO
* @return 0 if ok, -1 on error
*/
int gpio_request(unsigned gpio, const char *label);
/**
* Stop using the GPIO. This function should not alter pin configuration.
*
* @param gpio GPIO number
* @return 0 if ok, -1 on error
*/
int gpio_free(unsigned gpio);
/**
* Make a GPIO an input.
*
* @param gpio GPIO number
* @return 0 if ok, -1 on error
*/
int gpio_direction_input(unsigned gpio);
/**
* Make a GPIO an output, and set its value.
*
* @param gpio GPIO number
* @param value GPIO value (0 for low or 1 for high)
* @return 0 if ok, -1 on error
*/
int gpio_direction_output(unsigned gpio, int value);
/**
* Get a GPIO's value. This will work whether the GPIO is an input
* or an output.
*
* @param gpio GPIO number
* @return 0 if low, 1 if high, -1 on error
*/
int gpio_get_value(unsigned gpio);
/**
* Set an output GPIO's value. The GPIO must already be an output or
* this function may have no effect.
*
* @param gpio GPIO number
* @param value GPIO value (0 for low or 1 for high)
* @return 0 if ok, -1 on error
*/
int gpio_set_value(unsigned gpio, int value);
/* State of a GPIO, as reported by get_state() */
enum {
GPIOF_INPUT = 0,
GPIOF_OUTPUT,
GPIOF_UNKNOWN,
};
struct device;
/**
* struct struct dm_gpio_ops - Driver model GPIO operations
*
* Refer to functions above for description. These function largely copy
* the old API.
*
* This is trying to be close to Linux GPIO API. Once the U-Boot uses the
* new DM GPIO API, this should be really easy to flip over to the Linux
* GPIO API-alike interface.
*
* Akso it would be useful to standardise additional functions like
* pullup, slew rate and drive strength.
*
* gpio_request)( and gpio_free() are optional - if NULL then they will
* not be called.
*
* Note that @offset is the offset from the base GPIO of the device. So
* offset 0 is the device's first GPIO and offset o-1 is the last GPIO,
* where o is the number of GPIO lines controlled by the device. A device
* is typically used to control a single bank of GPIOs. Within complex
* SoCs there may be many banks and therefore many devices all referring
* to the different IO addresses within the SoC.
*
* The uclass combines all GPIO devices togther to provide a consistent
* numbering from 0 to n-1, where n is the number of GPIOs in total across
* all devices. Be careful not to confuse offset with gpio in the parameters.
*/
struct dm_gpio_ops {
int (*request)(struct device *dev, unsigned offset, const char *label);
int (*free)(struct device *dev, unsigned offset);
int (*direction_input)(struct device *dev, unsigned offset);
int (*direction_output)(struct device *dev, unsigned offset,
int value);
int (*get_value)(struct device *dev, unsigned offset);
int (*set_value)(struct device *dev, unsigned offset, int value);
int (*get_function)(struct device *dev, unsigned offset);
int (*get_state)(struct device *dev, unsigned offset, char *state,
int maxlen);
};
/**
* struct gpio_dev_priv - information about a device used by the uclass
*
* The uclass combines all active GPIO devices into a unified numbering
* scheme. To do this it maintains some private information aobut each
* device.
*
* To implement driver model support in your GPIO driver, add a probe
* handler, and set @gpio_count and @bank_name correctly in that handler.
* This tells the uclass the name of the GPIO bank and the number of GPIOs
* it contains.
*
* @bank_name: Name of the GPIO device (e.g 'a' means GPIOs will be called
* 'A0', 'A1', etc.
* @gpio_count: Number of GPIOs in this device
* @gpio_base: Base GPIO number for this device. For the first active device
* this will be 0; the numbering for others will follow sequentially so that
* @gpio_base for device 1 will equal the number of GPIOs in device 0.
*/
struct gpio_dev_priv {
const char *bank_name;
unsigned gpio_count;
unsigned gpio_base;
};
/* Access the GPIO operations for a device */
#define gpio_get_ops(dev) ((struct dm_gpio_ops *)(dev)->driver->ops)
/**
* gpio_get_bank_info - Return information about a GPIO bank/device
*
* This looks up a device and returns both its GPIO base name and the number
* of GPIOs it controls.
*
* @dev: Device to look up
* @offset_count: Returns number of GPIOs within this bank
* @return bank name of this device
*/
const char *gpio_get_bank_info(struct device *dev, int *offset_count);
/**
* gpio_lookup_name - Look up a GPIO name and return its details
*
* This is used to convert a named GPIO into a device, offset and GPIO
* number.
*
* @name: GPIO name to look up
* @devp: Returns pointer to device which contains this GPIO
* @offsetp: Returns the offset number within this device
* @gpiop: Returns the absolute GPIO number, numbered from 0
*/
int gpio_lookup_name(const char *name, struct device **devp,
unsigned int *offsetp, unsigned int *gpiop);
#endif /* _ASM_GENERIC_GPIO_H_ */
|
