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/kernel.h>
5#include <linux/types.h>
6#include <linux/errno.h>
7
8#ifdef CONFIG_GPIOLIB
9
10#include <linux/compiler.h>
11
12/* Platforms may implement their GPIO interface with library code,
13 * at a small performance cost for non-inlined operations and some
14 * extra memory (for code and for per-GPIO table entries).
15 *
16 * While the GPIO programming interface defines valid GPIO numbers
17 * to be in the range 0..MAX_INT, this library restricts them to the
18 * smaller range 0..ARCH_NR_GPIOS-1.
19 */
20
21#ifndef ARCH_NR_GPIOS
22#define ARCH_NR_GPIOS 256
23#endif
24
25static inline int gpio_is_valid(int number)
26{
27 /* only some non-negative numbers are valid */
28 return ((unsigned)number) < ARCH_NR_GPIOS;
29}
30
31struct device;
32struct seq_file;
33struct module;
34
35/**
36 * struct gpio_chip - abstract a GPIO controller
37 * @label: for diagnostics
38 * @dev: optional device providing the GPIOs
39 * @owner: helps prevent removal of modules exporting active GPIOs
40 * @request: optional hook for chip-specific activation, such as
41 * enabling module power and clock; may sleep
42 * @free: optional hook for chip-specific deactivation, such as
43 * disabling module power and clock; may sleep
44 * @direction_input: configures signal "offset" as input, or returns error
45 * @get: returns value for signal "offset"; for output signals this
46 * returns either the value actually sensed, or zero
47 * @direction_output: configures signal "offset" as output, or returns error
48 * @set: assigns output value for signal "offset"
49 * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
50 * implementation may not sleep
51 * @dbg_show: optional routine to show contents in debugfs; default code
52 * will be used when this is omitted, but custom code can show extra
53 * state (such as pullup/pulldown configuration).
54 * @base: identifies the first GPIO number handled by this chip; or, if
55 * negative during registration, requests dynamic ID allocation.
56 * @ngpio: the number of GPIOs handled by this controller; the last GPIO
57 * handled is (base + ngpio - 1).
58 * @can_sleep: flag must be set iff get()/set() methods sleep, as they
59 * must while accessing GPIO expander chips over I2C or SPI
60 * @names: if set, must be an array of strings to use as alternative
61 * names for the GPIOs in this chip. Any entry in the array
62 * may be NULL if there is no alias for the GPIO, however the
63 * array must be @ngpio entries long.
64 *
65 * A gpio_chip can help platforms abstract various sources of GPIOs so
66 * they can all be accessed through a common programing interface.
67 * Example sources would be SOC controllers, FPGAs, multifunction
68 * chips, dedicated GPIO expanders, and so on.
69 *
70 * Each chip controls a number of signals, identified in method calls
71 * by "offset" values in the range 0..(@ngpio - 1). When those signals
72 * are referenced through calls like gpio_get_value(gpio), the offset
73 * is calculated by subtracting @base from the gpio number.
74 */
75struct gpio_chip {
76 const char *label;
77 struct device *dev;
78 struct module *owner;
79
80 int (*request)(struct gpio_chip *chip,
81 unsigned offset);
82 void (*free)(struct gpio_chip *chip,
83 unsigned offset);
84
85 int (*direction_input)(struct gpio_chip *chip,
86 unsigned offset);
87 int (*get)(struct gpio_chip *chip,
88 unsigned offset);
89 int (*direction_output)(struct gpio_chip *chip,
90 unsigned offset, int value);
91 void (*set)(struct gpio_chip *chip,
92 unsigned offset, int value);
93
94 int (*to_irq)(struct gpio_chip *chip,
95 unsigned offset);
96
97 void (*dbg_show)(struct seq_file *s,
98 struct gpio_chip *chip);
99 int base;
100 u16 ngpio;
101 char **names;
102 unsigned can_sleep:1;
103 unsigned exported:1;
104};
105
106extern const char *gpiochip_is_requested(struct gpio_chip *chip,
107 unsigned offset);
108extern int __must_check gpiochip_reserve(int start, int ngpio);
109
110/* add/remove chips */
111extern int gpiochip_add(struct gpio_chip *chip);
112extern int __must_check gpiochip_remove(struct gpio_chip *chip);
113
114
115/* Always use the library code for GPIO management calls,
116 * or when sleeping may be involved.
117 */
118extern int gpio_request(unsigned gpio, const char *label);
119extern void gpio_free(unsigned gpio);
120
121extern int gpio_direction_input(unsigned gpio);
122extern int gpio_direction_output(unsigned gpio, int value);
123
124extern int gpio_get_value_cansleep(unsigned gpio);
125extern void gpio_set_value_cansleep(unsigned gpio, int value);
126
127
128/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
129 * the GPIO is constant and refers to some always-present controller,
130 * giving direct access to chip registers and tight bitbanging loops.
131 */
132extern int __gpio_get_value(unsigned gpio);
133extern void __gpio_set_value(unsigned gpio, int value);
134
135extern int __gpio_cansleep(unsigned gpio);
136
137extern int __gpio_to_irq(unsigned gpio);
138
139#ifdef CONFIG_GPIO_SYSFS
140
141/*
142 * A sysfs interface can be exported by individual drivers if they want,
143 * but more typically is configured entirely from userspace.
144 */
145extern int gpio_export(unsigned gpio, bool direction_may_change);
146extern int gpio_export_link(struct device *dev, const char *name,
147 unsigned gpio);
148extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
149extern void gpio_unexport(unsigned gpio);
150
151#endif /* CONFIG_GPIO_SYSFS */
152
153#else /* !CONFIG_HAVE_GPIO_LIB */
154
155static inline int gpio_is_valid(int number)
156{
157 /* only non-negative numbers are valid */
158 return number >= 0;
159}
160
161/* platforms that don't directly support access to GPIOs through I2C, SPI,
162 * or other blocking infrastructure can use these wrappers.
163 */
164
165static inline int gpio_cansleep(unsigned gpio)
166{
167 return 0;
168}
169
170static inline int gpio_get_value_cansleep(unsigned gpio)
171{
172 might_sleep();
173 return gpio_get_value(gpio);
174}
175
176static inline void gpio_set_value_cansleep(unsigned gpio, int value)
177{
178 might_sleep();
179 gpio_set_value(gpio, value);
180}
181
182#endif /* !CONFIG_HAVE_GPIO_LIB */
183
184#ifndef CONFIG_GPIO_SYSFS
185
186struct device;
187
188/* sysfs support is only available with gpiolib, where it's optional */
189
190static inline int gpio_export(unsigned gpio, bool direction_may_change)
191{
192 return -ENOSYS;
193}
194
195static inline int gpio_export_link(struct device *dev, const char *name,
196 unsigned gpio)
197{
198 return -ENOSYS;
199}
200
201static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
202{
203 return -ENOSYS;
204}
205
206static inline void gpio_unexport(unsigned gpio)
207{
208}
209#endif /* CONFIG_GPIO_SYSFS */
210
211#endif /* _ASM_GENERIC_GPIO_H */