Iterators for GPIO chips and lines

These functions and data structures allow easy iterating over GPIO chips and lines. More...

Macros
#define	gpiod_foreach_chip(iter, chip)
	Iterate over all GPIO chips present in the system. More...
#define	gpiod_foreach_chip_noclose(iter, chip)
	Iterate over all chips present in the system without closing them. More...
#define	gpiod_foreach_line(iter, line)
	Iterate over all GPIO lines of a single chip. More...

Functions
struct gpiod_chip_iter *	gpiod_chip_iter_new (void) GPIOD_API
	Create a new gpiochip iterator. More...
void	gpiod_chip_iter_free (struct gpiod_chip_iter *iter) GPIOD_API
	Release all resources allocated for the gpiochip iterator and close the most recently opened gpiochip (if any). More...
void	gpiod_chip_iter_free_noclose (struct gpiod_chip_iter *iter) GPIOD_API
	Release all resources allocated for the gpiochip iterator but don't close the most recently opened gpiochip (if any). More...
struct gpiod_chip *	gpiod_chip_iter_next (struct gpiod_chip_iter *iter) GPIOD_API
	Get the next gpiochip handle. More...
struct gpiod_chip *	gpiod_chip_iter_next_noclose (struct gpiod_chip_iter *iter) GPIOD_API
	Get the next gpiochip handle without closing the previous one. More...
struct gpiod_line_iter *	gpiod_line_iter_new (struct gpiod_chip *chip) GPIOD_API
	Create a new line iterator. More...
void	gpiod_line_iter_free (struct gpiod_line_iter *iter) GPIOD_API
	Free all resources associated with a GPIO line iterator. More...
struct gpiod_line *	gpiod_line_iter_next (struct gpiod_line_iter *iter) GPIOD_API
	Get the next GPIO line handle. More...

Detailed Description

These functions and data structures allow easy iterating over GPIO chips and lines.

Macro Definition Documentation

gpiod_foreach_chip

#define gpiod_foreach_chip	(		iter,
			chip
	)

Value:

        for ((chip) = gpiod_chip_iter_next(iter);                       \
             (chip);                                                    \
             (chip) = gpiod_chip_iter_next(iter))

Iterate over all GPIO chips present in the system.

Parameters

iter	An initialized GPIO chip iterator.
chip	Pointer to a GPIO chip handle. On each iteration the newly opened chip handle is assigned to this argument.

The user must not close the GPIO chip manually - instead the previous chip handle is closed automatically on the next iteration. The last chip to be opened is closed internally by gpiod_chip_iter_free.

Definition at line 1697 of file gpiod.h.

gpiod_foreach_chip_noclose

#define gpiod_foreach_chip_noclose	(		iter,
			chip
	)

Value:

        for ((chip) = gpiod_chip_iter_next_noclose(iter);               \
             (chip);                                                    \
             (chip) = gpiod_chip_iter_next_noclose(iter))

Iterate over all chips present in the system without closing them.

Parameters

iter	An initialized GPIO chip iterator.
chip	Pointer to a GPIO chip handle. On each iteration the newly opened chip handle is assigned to this argument.

The user must close all the GPIO chips manually after use, until then, the chips remain open. Free the iterator by calling gpiod_chip_iter_free_noclose to avoid closing the last chip automatically.

Definition at line 1712 of file gpiod.h.

gpiod_foreach_line

#define gpiod_foreach_line	(		iter,
			line
	)

Value:

        for ((line) = gpiod_line_iter_next(iter);                       \
             (line);                                                    \
             (line) = gpiod_line_iter_next(iter))

Iterate over all GPIO lines of a single chip.

Parameters

iter	An initialized GPIO line iterator.
line	Pointer to a GPIO line handle - on each iteration, the next GPIO line will be assigned to this argument.

Definition at line 1747 of file gpiod.h.

Function Documentation

gpiod_chip_iter_free()

void gpiod_chip_iter_free

(

struct gpiod_chip_iter *

iter

)

Release all resources allocated for the gpiochip iterator and close the most recently opened gpiochip (if any).

Parameters

iter	The gpiochip iterator object.

gpiod_chip_iter_free_noclose()

void gpiod_chip_iter_free_noclose

(

struct gpiod_chip_iter *

iter

)

Release all resources allocated for the gpiochip iterator but don't close the most recently opened gpiochip (if any).

Parameters

iter	The gpiochip iterator object.

Users may want to break the loop when iterating over gpiochips and keep the most recently opened chip active while freeing the iterator data. This routine enables that.

gpiod_chip_iter_new()

struct gpiod_chip_iter* gpiod_chip_iter_new

(

void

)

Create a new gpiochip iterator.

Returns

Pointer to a new chip iterator object or NULL if an error occurred.

Internally this routine scans the /dev/ directory for GPIO chip device files, opens them and stores their the handles until gpiod_chip_iter_free or gpiod_chip_iter_free_noclose is called.

gpiod_chip_iter_next()

struct gpiod_chip* gpiod_chip_iter_next

(

struct gpiod_chip_iter *

iter

)

Get the next gpiochip handle.

Parameters

iter	The gpiochip iterator object.

Returns

Pointer to the next open gpiochip handle or NULL if no more chips are present in the system.

Note

The previous chip handle will be closed using gpiod_chip_iter_free.

gpiod_chip_iter_next_noclose()

struct gpiod_chip* gpiod_chip_iter_next_noclose

(

struct gpiod_chip_iter *

iter

)

Get the next gpiochip handle without closing the previous one.

Parameters

iter	The gpiochip iterator object.

Returns

Pointer to the next open gpiochip handle or NULL if no more chips are present in the system.

Note

This function works just like gpiod_chip_iter_next but doesn't close the most recently opened chip handle.

gpiod_line_iter_free()

void gpiod_line_iter_free

(

struct gpiod_line_iter *

iter

)

Free all resources associated with a GPIO line iterator.

Parameters

iter	Line iterator object.

gpiod_line_iter_new()

struct gpiod_line_iter* gpiod_line_iter_new

(

struct gpiod_chip *

chip

)

Create a new line iterator.

Parameters

chip	Active gpiochip handle over the lines of which we want to iterate.

Returns

New line iterator or NULL if an error occurred.

gpiod_line_iter_next()

struct gpiod_line* gpiod_line_iter_next

(

struct gpiod_line_iter *

iter

)

Get the next GPIO line handle.

Parameters

iter	The GPIO line iterator object.

Returns

Pointer to the next GPIO line handle or NULL if there are no more lines left.