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 * @request: optional hook for chip-specific activation, such as
39 * enabling module power and clock; may sleep
40 * @free: optional hook for chip-specific deactivation, such as
41 * disabling module power and clock; may sleep
42 * @direction_input: configures signal "offset" as input, or returns error
43 * @get: returns value for signal "offset"; for output signals this
44 * returns either the value actually sensed, or zero
45 * @direction_output: configures signal "offset" as output, or returns error
46 * @set: assigns output value for signal "offset"
47 * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
48 * implementation may not sleep
49 * @dbg_show: optional routine to show contents in debugfs; default code
50 * will be used when this is omitted, but custom code can show extra
51 * state (such as pullup/pulldown configuration).
52 * @base: identifies the first GPIO number handled by this chip; or, if
53 * negative during registration, requests dynamic ID allocation.
54 * @ngpio: the number of GPIOs handled by this controller; the last GPIO
55 * handled is (base + ngpio - 1).
56 * @can_sleep: flag must be set iff get()/set() methods sleep, as they
57 * must while accessing GPIO expander chips over I2C or SPI
58 *
59 * A gpio_chip can help platforms abstract various sources of GPIOs so
60 * they can all be accessed through a common programing interface.
61 * Example sources would be SOC controllers, FPGAs, multifunction
62 * chips, dedicated GPIO expanders, and so on.
63 *
64 * Each chip controls a number of signals, identified in method calls
65 * by "offset" values in the range 0..(@ngpio - 1). When those signals
66 * are referenced through calls like gpio_get_value(gpio), the offset
67 * is calculated by subtracting @base from the gpio number.
68 */
69struct gpio_chip {
70 const char *label;
71 struct device *dev;
72 struct module *owner;
73
74 int (*request)(struct gpio_chip *chip,
75 unsigned offset);
76 void (*free)(struct gpio_chip *chip,
77 unsigned offset);
78
79 int (*direction_input)(struct gpio_chip *chip,
80 unsigned offset);
81 int (*get)(struct gpio_chip *chip,
82 unsigned offset);
83 int (*direction_output)(struct gpio_chip *chip,
84 unsigned offset, int value);
85 void (*set)(struct gpio_chip *chip,
86 unsigned offset, int value);
87
88 int (*to_irq)(struct gpio_chip *chip,
89 unsigned offset);
90
91 void (*dbg_show)(struct seq_file *s,
92 struct gpio_chip *chip);
93 int base;
94 u16 ngpio;
95 unsigned can_sleep:1;
96 unsigned exported:1;
97};
98
99extern const char *gpiochip_is_requested(struct gpio_chip *chip,
100 unsigned offset);
101extern int __must_check gpiochip_reserve(int start, int ngpio);
102
103/* add/remove chips */
104extern int gpiochip_add(struct gpio_chip *chip);
105extern int __must_check gpiochip_remove(struct gpio_chip *chip);
106
107
108/* Always use the library code for GPIO management calls,
109 * or when sleeping may be involved.
110 */
111extern int gpio_request(unsigned gpio, const char *label);
112extern void gpio_free(unsigned gpio);
113
114extern int gpio_direction_input(unsigned gpio);
115extern int gpio_direction_output(unsigned gpio, int value);
116
117extern int gpio_get_value_cansleep(unsigned gpio);
118extern void gpio_set_value_cansleep(unsigned gpio, int value);
119
120
121/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
122 * the GPIO is constant and refers to some always-present controller,
123 * giving direct access to chip registers and tight bitbanging loops.
124 */
125extern int __gpio_get_value(unsigned gpio);
126extern void __gpio_set_value(unsigned gpio, int value);
127
128extern int __gpio_cansleep(unsigned gpio);
129
130extern int __gpio_to_irq(unsigned gpio);
131
132#ifdef CONFIG_GPIO_SYSFS
133
134/*
135 * A sysfs interface can be exported by individual drivers if they want,
136 * but more typically is configured entirely from userspace.
137 */
138extern int gpio_export(unsigned gpio, bool direction_may_change);
139extern void gpio_unexport(unsigned gpio);
140
141#endif /* CONFIG_GPIO_SYSFS */
142
143#else /* !CONFIG_HAVE_GPIO_LIB */
144
145static inline int gpio_is_valid(int number)
146{
147 /* only non-negative numbers are valid */
148 return number >= 0;
149}
150
151/* platforms that don't directly support access to GPIOs through I2C, SPI,
152 * or other blocking infrastructure can use these wrappers.
153 */
154
155static inline int gpio_cansleep(unsigned gpio)
156{
157 return 0;
158}
159
160static inline int gpio_get_value_cansleep(unsigned gpio)
161{
162 might_sleep();
163 return gpio_get_value(gpio);
164}
165
166static inline void gpio_set_value_cansleep(unsigned gpio, int value)
167{
168 might_sleep();
169 gpio_set_value(gpio, value);
170}
171
172#endif /* !CONFIG_HAVE_GPIO_LIB */
173
174#ifndef CONFIG_GPIO_SYSFS
175
176/* sysfs support is only available with gpiolib, where it's optional */
177
178static inline int gpio_export(unsigned gpio, bool direction_may_change)
179{
180 return -ENOSYS;
181}
182
183static inline void gpio_unexport(unsigned gpio)
184{
185}
186#endif /* CONFIG_GPIO_SYSFS */
187
188#endif /* _ASM_GENERIC_GPIO_H */