Functions and data structures dealing with GPIO chips. More...

Functions
struct gpiod_chip *	gpiod_chip_open (const char *path) GPIOD_API
	Open a gpiochip by path. More...

struct gpiod_chip *	gpiod_chip_open_by_name (const char *name) GPIOD_API
	Open a gpiochip by name. More...

struct gpiod_chip *	gpiod_chip_open_by_number (unsigned int num) GPIOD_API
	Open a gpiochip by number. More...

struct gpiod_chip *	gpiod_chip_open_by_label (const char *label) GPIOD_API
	Open a gpiochip by label. More...

struct gpiod_chip *	gpiod_chip_open_lookup (const char *descr) GPIOD_API
	Open a gpiochip based on the best guess what the path is. More...

void	gpiod_chip_close (struct gpiod_chip *chip) GPIOD_API
	Close a GPIO chip handle and release all allocated resources. More...

const char *	gpiod_chip_name (struct gpiod_chip *chip) GPIOD_API
	Get the GPIO chip name as represented in the kernel. More...

const char *	gpiod_chip_label (struct gpiod_chip *chip) GPIOD_API
	Get the GPIO chip label as represented in the kernel. More...

unsigned int	gpiod_chip_num_lines (struct gpiod_chip *chip) GPIOD_API
	Get the number of GPIO lines exposed by this chip. More...

struct gpiod_line *	gpiod_chip_get_line (struct gpiod_chip *chip, unsigned int offset) GPIOD_API
	Get the handle to the GPIO line at given offset. More...

int	gpiod_chip_get_lines (struct gpiod_chip chip, unsigned int offsets, unsigned int num_offsets, struct gpiod_line_bulk *bulk) GPIOD_API
	Retrieve a set of lines and store them in a line bulk object. More...

int	gpiod_chip_get_all_lines (struct gpiod_chip chip, struct gpiod_line_bulk bulk) GPIOD_API
	Retrieve all lines exposed by a chip and store them in a bulk object. More...

struct gpiod_line *	gpiod_chip_find_line (struct gpiod_chip chip, const char name) GPIOD_API
	Find a GPIO line by name among lines associated with given GPIO chip. More...

int	gpiod_chip_find_lines (struct gpiod_chip chip, const char names, struct gpiod_line_bulk bulk) GPIOD_API
	Find a set of GPIO lines by names among lines exposed by this chip. More...

Detailed Description

Functions and data structures dealing with GPIO chips.

Function Documentation

◆ gpiod_chip_close()

void gpiod_chip_close ( struct gpiod_chip * chip )

Close a GPIO chip handle and release all allocated resources.

Parameters

chip	The GPIO chip object.

◆ gpiod_chip_find_line()

struct gpiod_line* gpiod_chip_find_line	(	struct gpiod_chip *	chip,
		const char *	name
	)

Find a GPIO line by name among lines associated with given GPIO chip.

Parameters

chip	The GPIO chip object.
name	The name of the GPIO line.

Returns: Pointer to the GPIO line handle or NULL if the line could not be found or an error occurred.

Note: In case a line with given name is not associated with given chip, the function sets errno to ENOENT.

Attention: GPIO line names are not unique in the linux kernel, neither globally nor within a single chip. This function finds the first line with given name.

◆ gpiod_chip_find_lines()

int gpiod_chip_find_lines	(	struct gpiod_chip *	chip,
		const char **	names,
		struct gpiod_line_bulk *	bulk
	)

Find a set of GPIO lines by names among lines exposed by this chip.

Parameters

chip	The GPIO chip object.
names	Array of pointers to C-strings containing the names of the lines to lookup. Must end with a NULL-pointer.
bulk	Line bulk object in which the located lines will be stored.

Returns: 0 if all lines were located, -1 on error.

Note: If at least one line from the list could not be found among the lines exposed by this chip, the function sets errno to ENOENT.

Attention: GPIO line names are not unique in the linux kernel, neither globally nor within a single chip. This function finds the first line with given name.

◆ gpiod_chip_get_all_lines()

int gpiod_chip_get_all_lines	(	struct gpiod_chip *	chip,
		struct gpiod_line_bulk *	bulk
	)

Retrieve all lines exposed by a chip and store them in a bulk object.

Parameters

chip	The GPIO chip object.
bulk	Line bulk object in which to store the line handles.

Returns: 0 on success, -1 on error.

◆ gpiod_chip_get_line()

struct gpiod_line* gpiod_chip_get_line	(	struct gpiod_chip *	chip,
		unsigned int	offset
	)

Get the handle to the GPIO line at given offset.

Parameters

chip	The GPIO chip object.
offset	The offset of the GPIO line.

Returns: Pointer to the GPIO line handle or NULL if an error occured.

◆ gpiod_chip_get_lines()

int gpiod_chip_get_lines	(	struct gpiod_chip *	chip,
		unsigned int *	offsets,
		unsigned int	num_offsets,
		struct gpiod_line_bulk *	bulk
	)

Retrieve a set of lines and store them in a line bulk object.

Parameters

chip	The GPIO chip object.
offsets	Array of offsets of lines to retrieve.
num_offsets	Number of lines to retrieve.
bulk	Line bulk object in which to store the line handles.

Returns: 0 on success, -1 on error.

◆ gpiod_chip_label()

const char* gpiod_chip_label ( struct gpiod_chip * chip )

Get the GPIO chip label as represented in the kernel.

Parameters

chip	The GPIO chip object.

Returns: Pointer to a human-readable string containing the chip label.

◆ gpiod_chip_name()

const char* gpiod_chip_name ( struct gpiod_chip * chip )

Get the GPIO chip name as represented in the kernel.

Parameters

chip	The GPIO chip object.

Returns: Pointer to a human-readable string containing the chip name.

◆ gpiod_chip_num_lines()

unsigned int gpiod_chip_num_lines ( struct gpiod_chip * chip )

Get the number of GPIO lines exposed by this chip.

Parameters

chip	The GPIO chip object.

Returns: Number of GPIO lines.

◆ gpiod_chip_open()

struct gpiod_chip* gpiod_chip_open ( const char * path )

Open a gpiochip by path.

Parameters

path	Path to the gpiochip device file.

Returns: GPIO chip handle or NULL if an error occurred.

◆ gpiod_chip_open_by_label()

struct gpiod_chip* gpiod_chip_open_by_label ( const char * label )

Open a gpiochip by label.

Parameters

label Label of the gpiochip to open.

Returns: GPIO chip handle or NULL if the chip with given label was not found or an error occured.

Note: If the chip cannot be found but no other error occurred, errno is set to ENOENT.

◆ gpiod_chip_open_by_name()

struct gpiod_chip* gpiod_chip_open_by_name ( const char * name )

Open a gpiochip by name.

Parameters

name	Name of the gpiochip to open.

Returns: GPIO chip handle or NULL if an error occurred.

This routine appends name to '/dev/' to create the path.

◆ gpiod_chip_open_by_number()

struct gpiod_chip* gpiod_chip_open_by_number ( unsigned int num )

Open a gpiochip by number.

Parameters

num	Number of the gpiochip.

Returns: GPIO chip handle or NULL if an error occurred.

This routine appends num to '/dev/gpiochip' to create the path.

◆ gpiod_chip_open_lookup()

struct gpiod_chip* gpiod_chip_open_lookup ( const char * descr )

Open a gpiochip based on the best guess what the path is.

Parameters

descr String describing the gpiochip.

Returns: GPIO chip handle or NULL if an error occurred.

This routine tries to figure out whether the user passed it the path to the GPIO chip, its name, label or number as a string. Then it tries to open it using one of the gpiod_chip_open** variants.