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
|
#ifndef _ASM_GENERIC_GPIO_H
#define _ASM_GENERIC_GPIO_H
#include <linux/types.h>
#include <linux/errno.h>
#ifdef CONFIG_GPIOLIB
#include <linux/compiler.h>
/* Platforms may implement their GPIO interface with library code,
* at a small performance cost for non-inlined operations and some
* extra memory (for code and for per-GPIO table entries).
*
* While the GPIO programming interface defines valid GPIO numbers
* to be in the range 0..MAX_INT, this library restricts them to the
* smaller range 0..ARCH_NR_GPIOS-1.
*/
#ifndef ARCH_NR_GPIOS
#define ARCH_NR_GPIOS 256
#endif
static inline int gpio_is_valid(int number)
{
/* only some non-negative numbers are valid */
return ((unsigned)number) < ARCH_NR_GPIOS;
}
struct seq_file;
struct module;
/**
* struct gpio_chip - abstract a GPIO controller
* @label: for diagnostics
* @dev: optional device providing the GPIOs
* @owner: helps prevent removal of modules exporting active GPIOs
* @direction_input: configures signal "offset" as input, or returns error
* @get: returns value for signal "offset"; for output signals this
* returns either the value actually sensed, or zero
* @direction_output: configures signal "offset" as output, or returns error
* @set: assigns output value for signal "offset"
* @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
* implementation may not sleep
* @dbg_show: optional routine to show contents in debugfs; default code
* will be used when this is omitted, but custom code can show extra
* state (such as pullup/pulldown configuration).
* @base: identifies the first GPIO number handled by this chip; or, if
* negative during registration, requests dynamic ID allocation.
* @ngpio: the number of GPIOs handled by this controller; the last GPIO
* handled is (base + ngpio - 1).
* @can_sleep: flag must be set iff get()/set() methods sleep, as they
* must while accessing GPIO expander chips over I2C or SPI
*
* A gpio_chip can help platforms abstract various sources of GPIOs so
* they can all be accessed through a common programing interface.
* Example sources would be SOC controllers, FPGAs, multifunction
* chips, dedicated GPIO expanders, and so on.
*
* Each chip controls a number of signals, identified in method calls
* by "offset" values in the range 0..(@ngpio - 1). When those signals
* are referenced through calls like gpio_get_value(gpio), the offset
* is calculated by subtracting @base from the gpio number.
*/
struct gpio_chip {
const char *label;
struct device *dev;
struct module *owner;
int (*direction_input)(struct gpio_chip *chip,
unsigned offset);
int (*get)(struct gpio_chip *chip,
unsigned offset);
int (*direction_output)(struct gpio_chip *chip,
unsigned offset, int value);
void (*set)(struct gpio_chip *chip,
unsigned offset, int value);
int (*to_irq)(struct gpio_chip *chip,
unsigned offset);
void (*dbg_show)(struct seq_file *s,
struct gpio_chip *chip);
int base;
u16 ngpio;
unsigned can_sleep:1;
unsigned exported:1;
};
extern const char *gpiochip_is_requested(struct gpio_chip *chip,
unsigned offset);
extern int __must_check gpiochip_reserve(int start, int ngpio);
/* add/remove chips */
extern int gpiochip_add(struct gpio_chip *chip);
extern int __must_check gpiochip_remove(struct gpio_chip *chip);
/* Always use the library code for GPIO management calls,
* or when sleeping may be involved.
*/
extern int gpio_request(unsigned gpio, const char *label);
extern void gpio_free(unsigned gpio);
extern int gpio_direction_input(unsigned gpio);
extern int gpio_direction_output(unsigned gpio, int value);
extern int gpio_get_value_cansleep(unsigned gpio);
extern void gpio_set_value_cansleep(unsigned gpio, int value);
/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
* the GPIO is constant and refers to some always-present controller,
* giving direct access to chip registers and tight bitbanging loops.
*/
extern int __gpio_get_value(unsigned gpio);
extern void __gpio_set_value(unsigned gpio, int value);
extern int __gpio_cansleep(unsigned gpio);
extern int __gpio_to_irq(unsigned gpio);
#ifdef CONFIG_GPIO_SYSFS
/*
* A sysfs interface can be exported by individual drivers if they want,
* but more typically is configured entirely from userspace.
*/
extern int gpio_export(unsigned gpio, bool direction_may_change);
extern void gpio_unexport(unsigned gpio);
#endif /* CONFIG_GPIO_SYSFS */
#else /* !CONFIG_HAVE_GPIO_LIB */
static inline int gpio_is_valid(int number)
{
/* only non-negative numbers are valid */
return number >= 0;
}
/* platforms that don't directly support access to GPIOs through I2C, SPI,
* or other blocking infrastructure can use these wrappers.
*/
static inline int gpio_cansleep(unsigned gpio)
{
return 0;
}
static inline int gpio_get_value_cansleep(unsigned gpio)
{
might_sleep();
return gpio_get_value(gpio);
}
static inline void gpio_set_value_cansleep(unsigned gpio, int value)
{
might_sleep();
gpio_set_value(gpio, value);
}
#endif /* !CONFIG_HAVE_GPIO_LIB */
#ifndef CONFIG_GPIO_SYSFS
/* sysfs support is only available with gpiolib, where it's optional */
static inline int gpio_export(unsigned gpio, bool direction_may_change)
{
return -ENOSYS;
}
static inline void gpio_unexport(unsigned gpio)
{
}
#endif /* CONFIG_GPIO_SYSFS */
#endif /* _ASM_GENERIC_GPIO_H */
|
