Root/include/asm-generic/gpio.h

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 * ARCH_NR_GPIOS is somewhat arbitrary; it usually reflects the sum of
21 * builtin/SoC GPIOs plus a number of GPIOs on expanders; the latter is
22 * actually an estimate of a board-specific value.
23 */
24
25#ifndef ARCH_NR_GPIOS
26#define ARCH_NR_GPIOS 256
27#endif
28
29/*
30 * "valid" GPIO numbers are nonnegative and may be passed to
31 * setup routines like gpio_request(). only some valid numbers
32 * can successfully be requested and used.
33 *
34 * Invalid GPIO numbers are useful for indicating no-such-GPIO in
35 * platform data and other tables.
36 */
37
38static inline int gpio_is_valid(int number)
39{
40    return ((unsigned)number) < ARCH_NR_GPIOS;
41}
42
43struct device;
44struct seq_file;
45struct module;
46struct device_node;
47
48/**
49 * struct gpio_chip - abstract a GPIO controller
50 * @label: for diagnostics
51 * @dev: optional device providing the GPIOs
52 * @owner: helps prevent removal of modules exporting active GPIOs
53 * @request: optional hook for chip-specific activation, such as
54 * enabling module power and clock; may sleep
55 * @free: optional hook for chip-specific deactivation, such as
56 * disabling module power and clock; may sleep
57 * @direction_input: configures signal "offset" as input, or returns error
58 * @get: returns value for signal "offset"; for output signals this
59 * returns either the value actually sensed, or zero
60 * @direction_output: configures signal "offset" as output, or returns error
61 * @set: assigns output value for signal "offset"
62 * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
63 * implementation may not sleep
64 * @dbg_show: optional routine to show contents in debugfs; default code
65 * will be used when this is omitted, but custom code can show extra
66 * state (such as pullup/pulldown configuration).
67 * @base: identifies the first GPIO number handled by this chip; or, if
68 * negative during registration, requests dynamic ID allocation.
69 * @ngpio: the number of GPIOs handled by this controller; the last GPIO
70 * handled is (base + ngpio - 1).
71 * @can_sleep: flag must be set iff get()/set() methods sleep, as they
72 * must while accessing GPIO expander chips over I2C or SPI
73 * @names: if set, must be an array of strings to use as alternative
74 * names for the GPIOs in this chip. Any entry in the array
75 * may be NULL if there is no alias for the GPIO, however the
76 * array must be @ngpio entries long. A name can include a single printk
77 * format specifier for an unsigned int. It is substituted by the actual
78 * number of the gpio.
79 *
80 * A gpio_chip can help platforms abstract various sources of GPIOs so
81 * they can all be accessed through a common programing interface.
82 * Example sources would be SOC controllers, FPGAs, multifunction
83 * chips, dedicated GPIO expanders, and so on.
84 *
85 * Each chip controls a number of signals, identified in method calls
86 * by "offset" values in the range 0..(@ngpio - 1). When those signals
87 * are referenced through calls like gpio_get_value(gpio), the offset
88 * is calculated by subtracting @base from the gpio number.
89 */
90struct gpio_chip {
91    const char *label;
92    struct device *dev;
93    struct module *owner;
94
95    int (*request)(struct gpio_chip *chip,
96                        unsigned offset);
97    void (*free)(struct gpio_chip *chip,
98                        unsigned offset);
99
100    int (*direction_input)(struct gpio_chip *chip,
101                        unsigned offset);
102    int (*get)(struct gpio_chip *chip,
103                        unsigned offset);
104    int (*direction_output)(struct gpio_chip *chip,
105                        unsigned offset, int value);
106    int (*set_debounce)(struct gpio_chip *chip,
107                        unsigned offset, unsigned debounce);
108
109    void (*set)(struct gpio_chip *chip,
110                        unsigned offset, int value);
111
112    int (*to_irq)(struct gpio_chip *chip,
113                        unsigned offset);
114
115    void (*dbg_show)(struct seq_file *s,
116                        struct gpio_chip *chip);
117    int base;
118    u16 ngpio;
119    const char *const *names;
120    unsigned can_sleep:1;
121    unsigned exported:1;
122
123#if defined(CONFIG_OF_GPIO)
124    /*
125     * If CONFIG_OF is enabled, then all GPIO controllers described in the
126     * device tree automatically may have an OF translation
127     */
128    struct device_node *of_node;
129    int of_gpio_n_cells;
130    int (*of_xlate)(struct gpio_chip *gc, struct device_node *np,
131                const void *gpio_spec, u32 *flags);
132#endif
133};
134
135extern const char *gpiochip_is_requested(struct gpio_chip *chip,
136            unsigned offset);
137extern int __must_check gpiochip_reserve(int start, int ngpio);
138
139/* add/remove chips */
140extern int gpiochip_add(struct gpio_chip *chip);
141extern int __must_check gpiochip_remove(struct gpio_chip *chip);
142extern struct gpio_chip *gpiochip_find(void *data,
143                    int (*match)(struct gpio_chip *chip,
144                             void *data));
145
146
147/* Always use the library code for GPIO management calls,
148 * or when sleeping may be involved.
149 */
150extern int gpio_request(unsigned gpio, const char *label);
151extern void gpio_free(unsigned gpio);
152
153extern int gpio_direction_input(unsigned gpio);
154extern int gpio_direction_output(unsigned gpio, int value);
155
156extern int gpio_set_debounce(unsigned gpio, unsigned debounce);
157
158extern int gpio_get_value_cansleep(unsigned gpio);
159extern void gpio_set_value_cansleep(unsigned gpio, int value);
160
161
162/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
163 * the GPIO is constant and refers to some always-present controller,
164 * giving direct access to chip registers and tight bitbanging loops.
165 */
166extern int __gpio_get_value(unsigned gpio);
167extern void __gpio_set_value(unsigned gpio, int value);
168
169extern int __gpio_cansleep(unsigned gpio);
170
171extern int __gpio_to_irq(unsigned gpio);
172
173#define GPIOF_DIR_OUT (0 << 0)
174#define GPIOF_DIR_IN (1 << 0)
175
176#define GPIOF_INIT_LOW (0 << 1)
177#define GPIOF_INIT_HIGH (1 << 1)
178
179#define GPIOF_IN (GPIOF_DIR_IN)
180#define GPIOF_OUT_INIT_LOW (GPIOF_DIR_OUT | GPIOF_INIT_LOW)
181#define GPIOF_OUT_INIT_HIGH (GPIOF_DIR_OUT | GPIOF_INIT_HIGH)
182
183/**
184 * struct gpio - a structure describing a GPIO with configuration
185 * @gpio: the GPIO number
186 * @flags: GPIO configuration as specified by GPIOF_*
187 * @label: a literal description string of this GPIO
188 */
189struct gpio {
190    unsigned gpio;
191    unsigned long flags;
192    const char *label;
193};
194
195extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
196extern int gpio_request_array(struct gpio *array, size_t num);
197extern void gpio_free_array(struct gpio *array, size_t num);
198
199#ifdef CONFIG_GPIO_SYSFS
200
201/*
202 * A sysfs interface can be exported by individual drivers if they want,
203 * but more typically is configured entirely from userspace.
204 */
205extern int gpio_export(unsigned gpio, bool direction_may_change);
206extern int gpio_export_link(struct device *dev, const char *name,
207            unsigned gpio);
208extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
209extern void gpio_unexport(unsigned gpio);
210
211#endif /* CONFIG_GPIO_SYSFS */
212
213#else /* !CONFIG_GPIOLIB */
214
215static inline int gpio_is_valid(int number)
216{
217    /* only non-negative numbers are valid */
218    return number >= 0;
219}
220
221/* platforms that don't directly support access to GPIOs through I2C, SPI,
222 * or other blocking infrastructure can use these wrappers.
223 */
224
225static inline int gpio_cansleep(unsigned gpio)
226{
227    return 0;
228}
229
230static inline int gpio_get_value_cansleep(unsigned gpio)
231{
232    might_sleep();
233    return gpio_get_value(gpio);
234}
235
236static inline void gpio_set_value_cansleep(unsigned gpio, int value)
237{
238    might_sleep();
239    gpio_set_value(gpio, value);
240}
241
242#endif /* !CONFIG_GPIOLIB */
243
244#ifndef CONFIG_GPIO_SYSFS
245
246struct device;
247
248/* sysfs support is only available with gpiolib, where it's optional */
249
250static inline int gpio_export(unsigned gpio, bool direction_may_change)
251{
252    return -ENOSYS;
253}
254
255static inline int gpio_export_link(struct device *dev, const char *name,
256                unsigned gpio)
257{
258    return -ENOSYS;
259}
260
261static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
262{
263    return -ENOSYS;
264}
265
266static inline void gpio_unexport(unsigned gpio)
267{
268}
269#endif /* CONFIG_GPIO_SYSFS */
270
271#endif /* _ASM_GENERIC_GPIO_H */
272

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