blob: 0f99ad38b012f93ef10ccb5b0f9105b4e7f8daab [file] [log] [blame]
#include <linux/types.h>
#include <linux/errno.h>
#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.
#define ARCH_NR_GPIOS 256
static inline int gpio_is_valid(int number)
/* only some non-negative numbers are valid */
return ((unsigned)number) < ARCH_NR_GPIOS;
struct seq_file;
struct module;
* struct gpio_chip - abstract a GPIO controller
* @label: for diagnostics
* @dev: optional device providing the GPIOs
* @owner: helps prevent removal of modules exporting active GPIOs
* @direction_input: configures signal "offset" as input, or returns error
* @get: returns value for signal "offset"; for output signals this
* returns either the value actually sensed, or zero
* @direction_output: configures signal "offset" as output, or returns error
* @set: assigns output value for signal "offset"
* @dbg_show: optional routine to show contents in debugfs; default code
* will be used when this is omitted, but custom code can show extra
* state (such as pullup/pulldown configuration).
* @base: identifies the first GPIO number handled by this chip; or, if
* negative during registration, requests dynamic ID allocation.
* @ngpio: the number of GPIOs handled by this controller; the last GPIO
* handled is (base + ngpio - 1).
* @can_sleep: flag must be set iff get()/set() methods sleep, as they
* must while accessing GPIO expander chips over I2C or SPI
* A gpio_chip can help platforms abstract various sources of GPIOs so
* they can all be accessed through a common programing interface.
* Example sources would be SOC controllers, FPGAs, multifunction
* chips, dedicated GPIO expanders, and so on.
* Each chip controls a number of signals, identified in method calls
* by "offset" values in the range 0..(@ngpio - 1). When those signals
* are referenced through calls like gpio_get_value(gpio), the offset
* is calculated by subtracting @base from the gpio number.
struct gpio_chip {
char *label;
struct device *dev;
struct module *owner;
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);
void (*set)(struct gpio_chip *chip,
unsigned offset, int value);
void (*dbg_show)(struct seq_file *s,
struct gpio_chip *chip);
int base;
u16 ngpio;
unsigned can_sleep:1;
unsigned exported:1;
extern const char *gpiochip_is_requested(struct gpio_chip *chip,
unsigned offset);
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);
/* 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_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);
* 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 void gpio_unexport(unsigned gpio);
#endif /* CONFIG_GPIO_SYSFS */
static inline int 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)
return gpio_get_value(gpio);
static inline void gpio_set_value_cansleep(unsigned gpio, int value)
gpio_set_value(gpio, value);
#endif /* !CONFIG_HAVE_GPIO_LIB */
/* 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 void gpio_unexport(unsigned gpio)
#endif /* CONFIG_GPIO_SYSFS */
#endif /* _ASM_GENERIC_GPIO_H */