GPIO

GPIO (General Peripheral Input/Output) More...

Data Structures
struct	pi_gpio_conf
	GPIO configuration structure. More...
struct	pi_gpio_callback_t
	GPIO callback struct. More...

Enumerations
enum	pi_gpio_flags_e
	GPIO configuration flags. More...
enum	pi_gpio_notif_e
	Sensitivity of a GPIO for notifications. More...

Functions
void	pi_gpio_conf_init (struct pi_gpio_conf *conf)
	Initialize a GPIO configuration with default values. More...
int	pi_gpio_open (struct pi_device *device)
	Open a GPIO device. More...
void	pi_gpio_close (struct pi_device *device)
	Close an opened GPIO device. More...
int	pi_gpio_pin_configure (struct pi_device *device, pi_gpio_e gpio, pi_gpio_flags_e flags)
	Configure a GPIO. More...
int	pi_gpio_pin_write (struct pi_device *device, uint32_t pin, uint32_t value)
	Set value of a single GPIO. More...
int	pi_gpio_pin_read (struct pi_device *device, uint32_t pin, uint32_t *value)
	Get value of a single GPIO. More...
void	pi_gpio_pin_notif_configure (struct pi_device *device, uint32_t pin, pi_gpio_notif_e flags)
	Configure notifications for a GPIO. More...
void	pi_gpio_pin_notif_clear (struct pi_device *device, uint32_t pin)
	Clear notification for a GPIO. More...
int	pi_gpio_pin_notif_get (struct pi_device *device, uint32_t pin)
	Get the value of a notification for a GPIO. More...
int	pi_gpio_pin_task_add (struct pi_device *device, uint32_t pin, pi_task_t *task, pi_gpio_notif_e flags)
	Attach an event task callback to a GPIO pin. More...
int	pi_gpio_pin_task_remove (struct pi_device *device, uint32_t pin)
	Remove an event task callback attached to a GPIO pin. More...
static void	pi_gpio_callback_init (pi_gpio_callback_t *cb, uint32_t pin_mask, pi_callback_func_t handler, void *arg)
	Init GPIO callback. More...
int	pi_gpio_callback_add (struct pi_device *device, pi_gpio_callback_t *cb)
	Attach a callback. More...
int	pi_gpio_callback_remove (struct pi_device *device, pi_gpio_callback_t *cb)
	Remove a callback. More...

Description

The GPIO driver provides support for controlling GPIOs. The available GPIOs are listed in pmsis/chips folder.

Enumeration Type Documentation

enum pi_gpio_flags_e

Flags to configure gpio : input/output mode, drive strength, pull activation.

Enumerator
PI_GPIO_PULL_DISABLE	Disable pull.
PI_GPIO_PULL_ENABLE	Enable pull.
PI_GPIO_DRIVE_STRENGTH_LOW	Low drive strength.
PI_GPIO_DRIVE_STRENGTH_HIGH	High drive strength.
PI_GPIO_INPUT	GPIO is an input.
PI_GPIO_OUTPUT	GPIO is an output.

enum pi_gpio_notif_e

This is used to tell which GPIO value modification will trigger a notification(IRQ).

Enumerator
PI_GPIO_NOTIF_FALL	IRQ are sent on a falling edge on the GPIO value.
PI_GPIO_NOTIF_RISE	IRQ are sent on a rising edge on the GPIO value.
PI_GPIO_NOTIF_EDGE	IRQ are sent on a rising or a falling edge on the GPIO value.
PI_GPIO_NOTIF_NONE	No IRQ.

Function Documentation

int pi_gpio_callback_add	(	struct pi_device *	device,
		pi_gpio_callback_t *	cb
	)

Add an application callback to a GPIO device. Multiple callbacks can be attached to a device, and to a GPIO pin.

Parameters

device	Pointer to device struct.
cb	Callback to add to the list.

Return values

0	If operation is successfull.
ERRNO	An error code otherwise.

Note

The callback can initialized with pi_gpio_callback_init().

Using callbacks is incompatible with event handling model(using event tasks cf. pi_gpio_pin_task_add()).

A callback is executed when a GPIO's corresponding bit is set in the callbask mask.

static void pi_gpio_callback_init ( pi_gpio_callback_t *  cb, uint32_t  pin_mask, pi_callback_func_t  handler, void *  arg  )

inlinestatic

Intialize a GPIO callback with the handler to call and the user args.

Parameters

cb	Pointer to callback to initialize.
pin_mask	Mask of GPIO pins.
handler	Callback function.
arg	Callback function arg.

int pi_gpio_callback_remove	(	struct pi_device *	device,
		pi_gpio_callback_t *	cb
	)

Remove an application callback from a GPIO device.

Parameters

device	Pointer to device struct.
cb	Callback to remove from the list.

Return values

0	If operation is successfull.
ERRNO	An error code otherwise.

void pi_gpio_close

(

struct pi_device *

device

)

This function closes a GPIO device. If memory was allocated, it is freed.

Parameters

device

A pointer to the device structure of the device to open.

Note

Closing a GPIO device will disable all GPIOs.

void pi_gpio_conf_init

(

struct pi_gpio_conf *

conf

)

The structure containing the configuration must be kept alive until the device is opened.

Parameters

conf	A pointer to the GPIO configuration.

int pi_gpio_open

(

struct pi_device *

device

)

This function must be called before the GPIO device can be used. It will do all the needed configuration to make it usable and initialize the handle used to refer to this opened device when calling other functions. This operation must be done once for each GPIO port, i.e. for every group of 32 GPIOs. The opened device can then be used to drive the 32 GPIOs.

Parameters

device

A pointer to the device structure of the device to open.

Return values

0	If the operation is successfull,
ERRNO	An error code otherwise.

Note

The device structure is allocated by the caller and must be kept alive until the device is closed.

int pi_gpio_pin_configure	(	struct pi_device *	device,
		pi_gpio_e	gpio,
		pi_gpio_flags_e	flags
	)

This function can be used to configure several aspects of a GPIO, like the direction.

Parameters

device	A pointer to the device structure this GPIO belongs to.
gpio	GPIO enumerate type or GPIO number within the port (from 0 to 31).
flags	A bitfield of flags specifying how to configure the GPIO.

Return values

0	If the operation is successfull.
ERRNO	An error code otherwise.

void pi_gpio_pin_notif_clear	(	struct pi_device *	device,
		uint32_t	pin
	)

This function can be used to clear the notification of a GPIO. A GPIO notification is buffered and ths function must be called to clear it so that a new one can be seen.

Parameters

device	A pointer to the device structure this GPIO belongs to.
pin	The GPIO number within the port (from 0 to 31).

Note

The pin parameter can be a GPIO enumerate type pi_gpio_e.

void pi_gpio_pin_notif_configure	(	struct pi_device *	device,
		uint32_t	pin,
		pi_gpio_notif_e	flags
	)

This function can be used to configure how to be notified by GPIO value modifications. By default, notifications will be buffered and can be read and cleared.

Parameters

device	A pointer to the device structure this GPIO belongs to.
pin	The GPIO number within the port (from 0 to 31).
flags	The flags to configure how the notification should be triggered.

Note

The pin parameter can be a GPIO enumerate type pi_gpio_e.

int pi_gpio_pin_notif_get	(	struct pi_device *	device,
		uint32_t	pin
	)

This function can be used to get the value of a notification of a GPIO. It returns 1 if at least one notification was received since the last time it was cleared. Reading the notification does not clear it.

Parameters

device	A pointer to the device structure this GPIO belongs to.
pin	The GPIO number within the port (from 0 to 31).

Return values

0	If a notification was received.
1	Otherwise.

Note

The pin parameter can be a GPIO enumerate type pi_gpio_e.

int pi_gpio_pin_read	(	struct pi_device *	device,
		uint32_t	pin,
		uint32_t *	value
	)

This function can be used to get the value of a single GPIO. It will store the current input value of a GPIO pin into a given buffer.

Parameters

device	A pointer to the device structure this GPIO belongs to.
pin	The GPIO number within the port (from 0 to 31).
value	A pointer to the variable where the GPIO value should be returned. The value will be either 0 or 1.

Return values

0	If the operation is successfull.
ERRNO	An error code otherwise.

Note

The pin parameter can be a GPIO enumerate type pi_gpio_e.

This function should be used on GPIO pins configured as PI_GPIO_INPUT. Although this function can be used to retrieve current value set on a GPIO pin configured as PI_GPIO_OUTPUT.

int pi_gpio_pin_task_add	(	struct pi_device *	device,
		uint32_t	pin,
		pi_task_t *	task,
		pi_gpio_notif_e	flags
	)

This function is used to attach a callback that will be called when a GPIO triggers an IRQ.

This callback is executed by the event kernel.

Parameters

device	A pointer to the device structure this GPIO belongs to.
pin	The GPIO number within the port (from 0 to 31).
task	Event task executed when an IRQ is triggered.
flags	The flags to configure how the notification should be triggered.

Return values

0	If the operation is successfull.
ERRNO	An error code otherwise.

Note

The pin parameter can be a GPIO enumerate type pi_gpio_e.

int pi_gpio_pin_task_remove	(	struct pi_device *	device,
		uint32_t	pin
	)

This function is used to remove an attached callback to a GPIO pin. If a IRQ is triggered on the given pin, after removal of the event task, no handler will executed.

Parameters

device	A pointer to the device structure this GPIO belongs to.
pin	The GPIO number within the port (from 0 to 31).

Return values

0	If the operation is successfull.
ERRNO	An error code otherwise.

Note

The pin parameter can be a GPIO enumerate type pi_gpio_e.

int pi_gpio_pin_write	(	struct pi_device *	device,
		uint32_t	pin,
		uint32_t	value
	)

This function can be used to change the value of a single GPIO.

Parameters

device	A pointer to the device structure this GPIO belongs to.
pin	The GPIO number within the port (from 0 to 31).
value	The value to be set. This can be either 0 or 1.

Return values

0	If the operation is successfull.
ERRNO	An error code otherwise.

Note

The pin parameter can be a GPIO enumerate type pi_gpio_e.

This function is to be used on GPIO pins configured as PI_GPIO_OUTPUT.