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
19static inline int gpio_is_valid(int number)
20{
21 /* only some non-negative numbers are valid */
22 return ((unsigned)number) < ARCH_NR_GPIOS;
23}
24
25struct seq_file;
26struct module;
27
28/**
29 * struct gpio_chip - abstract a GPIO controller
30 * @label: for diagnostics
31 * @direction_input: configures signal "offset" as input, or returns error
32 * @get: returns value for signal "offset"; for output signals this
33 * returns either the value actually sensed, or zero
34 * @direction_output: configures signal "offset" as output, or returns error
35 * @set: assigns output value for signal "offset"
36 * @dbg_show: optional routine to show contents in debugfs; default code
37 * will be used when this is omitted, but custom code can show extra
38 * state (such as pullup/pulldown configuration).
39 * @base: identifies the first GPIO number handled by this chip; or, if
40 * negative during registration, requests dynamic ID allocation.
41 * @ngpio: the number of GPIOs handled by this controller; the last GPIO
42 * handled is (base + ngpio - 1).
43 * @can_sleep: flag must be set iff get()/set() methods sleep, as they
44 * must while accessing GPIO expander chips over I2C or SPI
45 *
46 * A gpio_chip can help platforms abstract various sources of GPIOs so
47 * they can all be accessed through a common programing interface.
48 * Example sources would be SOC controllers, FPGAs, multifunction
49 * chips, dedicated GPIO expanders, and so on.
50 *
51 * Each chip controls a number of signals, identified in method calls
52 * by "offset" values in the range 0..(@ngpio - 1). When those signals
53 * are referenced through calls like gpio_get_value(gpio), the offset
54 * is calculated by subtracting @base from the gpio number.
55 */
56struct gpio_chip {
57 char *label;
58 struct module *owner;
59
60 int (*direction_input)(struct gpio_chip *chip,
61 unsigned offset);
62 int (*get)(struct gpio_chip *chip,
63 unsigned offset);
64 int (*direction_output)(struct gpio_chip *chip,
65 unsigned offset, int value);
66 void (*set)(struct gpio_chip *chip,
67 unsigned offset, int value);
68 void (*dbg_show)(struct seq_file *s,
69 struct gpio_chip *chip);
70 int base;
71 u16 ngpio;
72 unsigned can_sleep:1;
73};
74
75extern const char *gpiochip_is_requested(struct gpio_chip *chip,
76 unsigned offset);
77extern int __init __must_check gpiochip_reserve(int start, int ngpio);
78
79/* add/remove chips */
80extern int gpiochip_add(struct gpio_chip *chip);
81extern int __must_check gpiochip_remove(struct gpio_chip *chip);
82
83
84/* Always use the library code for GPIO management calls,
85 * or when sleeping may be involved.
86 */
87extern int gpio_request(unsigned gpio, const char *label);
88extern void gpio_free(unsigned gpio);
89
90extern int gpio_direction_input(unsigned gpio);
91extern int gpio_direction_output(unsigned gpio, int value);
92
93extern int gpio_get_value_cansleep(unsigned gpio);
94extern void gpio_set_value_cansleep(unsigned gpio, int value);
95
96
97/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
98 * the GPIO is constant and refers to some always-present controller,
99 * giving direct access to chip registers and tight bitbanging loops.
100 */
101extern int __gpio_get_value(unsigned gpio);
102extern void __gpio_set_value(unsigned gpio, int value);
103
104extern int __gpio_cansleep(unsigned gpio);
105
106
107#else
108
109static inline int gpio_is_valid(int number)
110{
111 /* only non-negative numbers are valid */
112 return number >= 0;
113}
114
115/* platforms that don't directly support access to GPIOs through I2C, SPI,
116 * or other blocking infrastructure can use these wrappers.
117 */
118
119static inline int gpio_cansleep(unsigned gpio)
120{
121 return 0;
122}
123
124static inline int gpio_get_value_cansleep(unsigned gpio)
125{
126 might_sleep();
127 return gpio_get_value(gpio);
128}
129
130static inline void gpio_set_value_cansleep(unsigned gpio, int value)
131{
132 might_sleep();
133 gpio_set_value(gpio, value);
134}
135
136#endif
137
138#endif /* _ASM_GENERIC_GPIO_H */