tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#ifndef _ASM_GENERIC_GPIO_H
2#define _ASM_GENERIC_GPIO_H
3
4#include <linux/types.h>
5#include <linux/errno.h>
6
7#ifdef CONFIG_GPIOLIB
8
9#include <linux/compiler.h>
10
11/* Platforms may implement their GPIO interface with library code,
12 * at a small performance cost for non-inlined operations and some
13 * extra memory (for code and for per-GPIO table entries).
14 *
15 * While the GPIO programming interface defines valid GPIO numbers
16 * to be in the range 0..MAX_INT, this library restricts them to the
17 * smaller range 0..ARCH_NR_GPIOS-1.
18 */
19
20#ifndef ARCH_NR_GPIOS
21#define ARCH_NR_GPIOS 256
22#endif
23
24static inline int gpio_is_valid(int number)
25{
26 /* only some non-negative numbers are valid */
27 return ((unsigned)number) < ARCH_NR_GPIOS;
28}
29
30struct seq_file;
31struct module;
32
33/**
34 * struct gpio_chip - abstract a GPIO controller
35 * @label: for diagnostics
36 * @dev: optional device providing the GPIOs
37 * @owner: helps prevent removal of modules exporting active GPIOs
38 * @direction_input: configures signal "offset" as input, or returns error
39 * @get: returns value for signal "offset"; for output signals this
40 * returns either the value actually sensed, or zero
41 * @direction_output: configures signal "offset" as output, or returns error
42 * @set: assigns output value for signal "offset"
43 * @dbg_show: optional routine to show contents in debugfs; default code
44 * will be used when this is omitted, but custom code can show extra
45 * state (such as pullup/pulldown configuration).
46 * @base: identifies the first GPIO number handled by this chip; or, if
47 * negative during registration, requests dynamic ID allocation.
48 * @ngpio: the number of GPIOs handled by this controller; the last GPIO
49 * handled is (base + ngpio - 1).
50 * @can_sleep: flag must be set iff get()/set() methods sleep, as they
51 * must while accessing GPIO expander chips over I2C or SPI
52 *
53 * A gpio_chip can help platforms abstract various sources of GPIOs so
54 * they can all be accessed through a common programing interface.
55 * Example sources would be SOC controllers, FPGAs, multifunction
56 * chips, dedicated GPIO expanders, and so on.
57 *
58 * Each chip controls a number of signals, identified in method calls
59 * by "offset" values in the range 0..(@ngpio - 1). When those signals
60 * are referenced through calls like gpio_get_value(gpio), the offset
61 * is calculated by subtracting @base from the gpio number.
62 */
63struct gpio_chip {
64 char *label;
65 struct device *dev;
66 struct module *owner;
67
68 int (*direction_input)(struct gpio_chip *chip,
69 unsigned offset);
70 int (*get)(struct gpio_chip *chip,
71 unsigned offset);
72 int (*direction_output)(struct gpio_chip *chip,
73 unsigned offset, int value);
74 void (*set)(struct gpio_chip *chip,
75 unsigned offset, int value);
76 void (*dbg_show)(struct seq_file *s,
77 struct gpio_chip *chip);
78 int base;
79 u16 ngpio;
80 unsigned can_sleep:1;
81 unsigned exported:1;
82};
83
84extern const char *gpiochip_is_requested(struct gpio_chip *chip,
85 unsigned offset);
86extern int __must_check gpiochip_reserve(int start, int ngpio);
87
88/* add/remove chips */
89extern int gpiochip_add(struct gpio_chip *chip);
90extern int __must_check gpiochip_remove(struct gpio_chip *chip);
91
92
93/* Always use the library code for GPIO management calls,
94 * or when sleeping may be involved.
95 */
96extern int gpio_request(unsigned gpio, const char *label);
97extern void gpio_free(unsigned gpio);
98
99extern int gpio_direction_input(unsigned gpio);
100extern int gpio_direction_output(unsigned gpio, int value);
101
102extern int gpio_get_value_cansleep(unsigned gpio);
103extern void gpio_set_value_cansleep(unsigned gpio, int value);
104
105
106/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
107 * the GPIO is constant and refers to some always-present controller,
108 * giving direct access to chip registers and tight bitbanging loops.
109 */
110extern int __gpio_get_value(unsigned gpio);
111extern void __gpio_set_value(unsigned gpio, int value);
112
113extern int __gpio_cansleep(unsigned gpio);
114
115
116#ifdef CONFIG_GPIO_SYSFS
117
118/*
119 * A sysfs interface can be exported by individual drivers if they want,
120 * but more typically is configured entirely from userspace.
121 */
122extern int gpio_export(unsigned gpio, bool direction_may_change);
123extern void gpio_unexport(unsigned gpio);
124
125#endif /* CONFIG_GPIO_SYSFS */
126
127#else /* !CONFIG_HAVE_GPIO_LIB */
128
129static inline int gpio_is_valid(int number)
130{
131 /* only non-negative numbers are valid */
132 return number >= 0;
133}
134
135/* platforms that don't directly support access to GPIOs through I2C, SPI,
136 * or other blocking infrastructure can use these wrappers.
137 */
138
139static inline int gpio_cansleep(unsigned gpio)
140{
141 return 0;
142}
143
144static inline int gpio_get_value_cansleep(unsigned gpio)
145{
146 might_sleep();
147 return gpio_get_value(gpio);
148}
149
150static inline void gpio_set_value_cansleep(unsigned gpio, int value)
151{
152 might_sleep();
153 gpio_set_value(gpio, value);
154}
155
156#endif /* !CONFIG_HAVE_GPIO_LIB */
157
158#ifndef CONFIG_GPIO_SYSFS
159
160/* sysfs support is only available with gpiolib, where it's optional */
161
162static inline int gpio_export(unsigned gpio, bool direction_may_change)
163{
164 return -ENOSYS;
165}
166
167static inline void gpio_unexport(unsigned gpio)
168{
169}
170#endif /* CONFIG_GPIO_SYSFS */
171
172#endif /* _ASM_GENERIC_GPIO_H */