gpio.h

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#ifndef _ASM_GENERIC_GPIO_H
#define _ASM_GENERIC_GPIO_H

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/of.h>

#ifdef CONFIG_GPIOLIB

#include <linux/compiler.h>

/* Platforms may implement their GPIO interface with library code,
 * at a small performance cost for non-inlined operations and some
 * extra memory (for code and for per-GPIO table entries).
 *
 * While the GPIO programming interface defines valid GPIO numbers
 * to be in the range 0..MAX_INT, this library restricts them to the
 * smaller range 0..ARCH_NR_GPIOS-1.
 *
 * ARCH_NR_GPIOS is somewhat arbitrary; it usually reflects the sum of
 * builtin/SoC GPIOs plus a number of GPIOs on expanders; the latter is
 * actually an estimate of a board-specific value.
 */

#ifndef ARCH_NR_GPIOS
#define ARCH_NR_GPIOS       256
#endif

/*
 * "valid" GPIO numbers are nonnegative and may be passed to
 * setup routines like gpio_request().  only some valid numbers
 * can successfully be requested and used.
 *
 * Invalid GPIO numbers are useful for indicating no-such-GPIO in
 * platform data and other tables.
 */

static inline bool gpio_is_valid(int number)
{
    return number >= 0 && number < ARCH_NR_GPIOS;
}

struct device;
struct gpio;
struct seq_file;
struct module;
struct device_node;

struct gpio_chip {
    const char      *label;
    struct device       *dev;
    struct module       *owner;

    int         (*request)(struct gpio_chip *chip,
                        unsigned offset);
    void            (*free)(struct gpio_chip *chip,
                        unsigned offset);

    int         (*direction_input)(struct gpio_chip *chip,
                        unsigned offset);
    int         (*get)(struct gpio_chip *chip,
                        unsigned offset);
    int         (*direction_output)(struct gpio_chip *chip,
                        unsigned offset, int value);
    int         (*set_debounce)(struct gpio_chip *chip,
                        unsigned offset, unsigned debounce);

    void            (*set)(struct gpio_chip *chip,
                        unsigned offset, int value);

    int         (*to_irq)(struct gpio_chip *chip,
                        unsigned offset);

    void            (*dbg_show)(struct seq_file *s,
                        struct gpio_chip *chip);
    int         base;
    u16         ngpio;
    const char      *const *names;
    unsigned        can_sleep:1;
    unsigned        exported:1;

#if defined(CONFIG_OF_GPIO)
    /*
     * If CONFIG_OF is enabled, then all GPIO controllers described in the
     * device tree automatically may have an OF translation
     */
    struct device_node *of_node;
    int of_gpio_n_cells;
    int (*of_xlate)(struct gpio_chip *gc,
                const struct of_phandle_args *gpiospec, u32 *flags);
#endif
};

extern const char *gpiochip_is_requested(struct gpio_chip *chip,
            unsigned offset);
extern struct gpio_chip *gpio_to_chip(unsigned gpio);
extern int __must_check gpiochip_reserve(int start, int ngpio);

/* add/remove chips */
extern int gpiochip_add(struct gpio_chip *chip);
extern int __must_check gpiochip_remove(struct gpio_chip *chip);
extern struct gpio_chip *gpiochip_find(void *data,
                    int (*match)(struct gpio_chip *chip,
                             void *data));


/* Always use the library code for GPIO management calls,
 * or when sleeping may be involved.
 */
extern int gpio_request(unsigned gpio, const char *label);
extern void gpio_free(unsigned gpio);

extern int gpio_direction_input(unsigned gpio);
extern int gpio_direction_output(unsigned gpio, int value);

extern int gpio_set_debounce(unsigned gpio, unsigned debounce);

extern int gpio_get_value_cansleep(unsigned gpio);
extern void gpio_set_value_cansleep(unsigned gpio, int value);


/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
 * the GPIO is constant and refers to some always-present controller,
 * giving direct access to chip registers and tight bitbanging loops.
 */
extern int __gpio_get_value(unsigned gpio);
extern void __gpio_set_value(unsigned gpio, int value);

extern int __gpio_cansleep(unsigned gpio);

extern int __gpio_to_irq(unsigned gpio);

extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
extern int gpio_request_array(const struct gpio *array, size_t num);
extern void gpio_free_array(const struct gpio *array, size_t num);

/* bindings for managed devices that want to request gpios */
int devm_gpio_request(struct device *dev, unsigned gpio, const char *label);
int devm_gpio_request_one(struct device *dev, unsigned gpio,
              unsigned long flags, const char *label);
void devm_gpio_free(struct device *dev, unsigned int gpio);

#ifdef CONFIG_GPIO_SYSFS

/*
 * A sysfs interface can be exported by individual drivers if they want,
 * but more typically is configured entirely from userspace.
 */
extern int gpio_export(unsigned gpio, bool direction_may_change);
extern int gpio_export_link(struct device *dev, const char *name,
            unsigned gpio);
extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
extern void gpio_unexport(unsigned gpio);

#endif  /* CONFIG_GPIO_SYSFS */

#else   /* !CONFIG_GPIOLIB */

static inline bool gpio_is_valid(int number)
{
    /* only non-negative numbers are valid */
    return number >= 0;
}

/* platforms that don't directly support access to GPIOs through I2C, SPI,
 * or other blocking infrastructure can use these wrappers.
 */

static inline int gpio_cansleep(unsigned gpio)
{
    return 0;
}

static inline int gpio_get_value_cansleep(unsigned gpio)
{
    might_sleep();
    return __gpio_get_value(gpio);
}

static inline void gpio_set_value_cansleep(unsigned gpio, int value)
{
    might_sleep();
    __gpio_set_value(gpio, value);
}

#endif /* !CONFIG_GPIOLIB */

#ifndef CONFIG_GPIO_SYSFS

struct device;

/* sysfs support is only available with gpiolib, where it's optional */

static inline int gpio_export(unsigned gpio, bool direction_may_change)
{
    return -ENOSYS;
}

static inline int gpio_export_link(struct device *dev, const char *name,
                unsigned gpio)
{
    return -ENOSYS;
}

static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
{
    return -ENOSYS;
}

static inline void gpio_unexport(unsigned gpio)
{
}
#endif  /* CONFIG_GPIO_SYSFS */

#endif /* _ASM_GENERIC_GPIO_H */