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