Main API

Main data structures and functions. More...

Modules
	Register Access
	Register access functions.

Data Structures
struct	i2cd
	Handle to an I2C character device. More...

Functions
struct i2cd *	i2cd_open (const char *path)
	Open the I2C character device specified by path. More...
struct i2cd *	i2cd_open_by_name (const char *name)
	Open the I2C character device specified by name. More...
struct i2cd *	i2cd_open_by_number (unsigned int num)
	Open the I2C character device specified by num. More...
void	i2cd_close (struct i2cd *dev)
	Close an I2C character device handle and free associated memory. More...
const char *	i2cd_get_path (struct i2cd *dev)
	Get the path used to open the I2C character device handle. More...
int	i2cd_set_retries (struct i2cd *dev, unsigned long retries)
	Set the number of times a slave address should be polled when not acknowledging. More...
int	i2cd_set_timeout (struct i2cd *dev, unsigned long timeout)
	Set the timeout in units of 10ms. More...
int	i2cd_get_functionality (struct i2cd *dev, unsigned long *funcs)
	Get the adapter functionality mask. More...
int	i2cd_transfer (struct i2cd *dev, struct i2c_msg msgs[], size_t nmsgs)
	Transfer one or more low-level messages terminated with a single STOP condition. More...
int	i2cd_read (struct i2cd *dev, uint16_t addr, void *buf, size_t len)
	Read bytes from a slave device. More...
int	i2cd_write (struct i2cd *dev, uint16_t addr, const void *buf, size_t len)
	Write bytes to a slave device. More...
int	i2cd_write_read (struct i2cd *dev, uint16_t addr, const void *write_buf, size_t write_len, void *read_buf, size_t read_len)
	Write and read bytes from a slave device using a repeated START condition. More...

Detailed Description

Main data structures and functions.

#include <i2cd.h>

Function Documentation

i2cd_close()

void i2cd_close

(

struct i2cd *

dev

)

Close an I2C character device handle and free associated memory.

Parameters

dev	Pointer to an I2C character device handle.

Once closed, dev is no longer valid for use.

i2cd_get_functionality()

int i2cd_get_functionality	(	struct i2cd *	dev,
		unsigned long *	funcs
	)

Get the adapter functionality mask.

Parameters

dev	Pointer to an I2C character device handle.
funcs	Pointer to a buffer to receive a mask.

Returns

0 on success, or -1 on error with errno set appropriately.

Adapter functionality can be determined by comparing the returned mask to values defined by the I2C_FUNC_* macros in linux/i2c.h.

This function corresponds to the I2C_FUNCS ioctl() request.

i2cd_get_path()

const char* i2cd_get_path

(

struct i2cd *

dev

)

Get the path used to open the I2C character device handle.

Parameters

dev	Pointer to an I2C character device handle.

Returns

The path used to open the I2C character device handle.

i2cd_open()

struct i2cd* i2cd_open

(

const char *

path

)

Open the I2C character device specified by path.

Parameters

path	Path to the I2C character device to open.

Returns

Pointer to an I2C character device handle, or NULL on error with errno set appropriately.

i2cd_open_by_name()

struct i2cd* i2cd_open_by_name

(

const char *

name

)

Open the I2C character device specified by name.

Parameters

name	Name of the I2C character device to open.

Returns

Pointer to an I2C character device handle, or NULL on error with errno set appropriately.

This function is equivalent to calling:

char path[PATH_MAX];
snprintf(path, sizeof(path), "/dev/%s", name);
i2cd_open(path);

i2cd_open_by_number()

struct i2cd* i2cd_open_by_number

(

unsigned int

num

)

Open the I2C character device specified by num.

Parameters

num	Number of the I2C character device to open.

Returns

Pointer to an I2C character device handle, or NULL on error with errno set appropriately.

This function is equivalent to calling:

char path[PATH_MAX];
snprintf(path, sizeof(path), "/dev/i2c-%u", num);
i2cd_open(path);

i2cd_read()

int i2cd_read	(	struct i2cd *	dev,
		uint16_t	addr,
		void *	buf,
		size_t	len
	)

Read bytes from a slave device.

Parameters

dev	Pointer to an I2C character device handle.
addr	I2C slave address.
buf	Pointer to a buffer to receive bytes.
len	Number of bytes to read.

Returns

Number of messages transferred on success, or -1 on error with errno set appropriately.

i2cd_set_retries()

int i2cd_set_retries	(	struct i2cd *	dev,
		unsigned long	retries
	)

Set the number of times a slave address should be polled when not acknowledging.

Parameters

dev	Pointer to an I2C character device handle.
retries	Number of times to retry.

Returns

0 on success, or -1 on error with errno set appropriately.

This function corresponds to the I2C_RETRIES ioctl() request.

i2cd_set_timeout()

int i2cd_set_timeout	(	struct i2cd *	dev,
		unsigned long	timeout
	)

Set the timeout in units of 10ms.

Parameters

dev	Pointer to an I2C character device handle.
timeout	Timeout in units of 10ms.

Returns

0 on success, or -1 on error with errno set appropriately.

This function corresponds to the I2C_TIMEOUT ioctl() request.

i2cd_transfer()

int i2cd_transfer	(	struct i2cd *	dev,
		struct i2c_msg	msgs[],
		size_t	nmsgs
	)

Transfer one or more low-level messages terminated with a single STOP condition.

Parameters

dev	Pointer to an I2C character device handle.
msgs	Array of messages to transfer.
nmsgs	Number of messages to transfer.

Returns

Number of messages transferred on success, or -1 on error with errno set appropriately.

This function corresponds to the I2C_RDWR ioctl() request.

i2cd_write()

int i2cd_write	(	struct i2cd *	dev,
		uint16_t	addr,
		const void *	buf,
		size_t	len
	)

Write bytes to a slave device.

Parameters

dev	Pointer to an I2C character device handle.
addr	I2C slave address.
buf	Pointer to a buffer to send bytes.
len	Number of bytes to send.

Returns

Number of messages transferred on success, or -1 on error with errno set appropriately.

i2cd_write_read()

int i2cd_write_read	(	struct i2cd *	dev,
		uint16_t	addr,
		const void *	write_buf,
		size_t	write_len,
		void *	read_buf,
		size_t	read_len
	)

Write and read bytes from a slave device using a repeated START condition.

Parameters

dev	Pointer to an I2C character device handle.
addr	I2C slave address.
write_buf	Pointer to a buffer to send bytes.
write_len	Number of bytes to send.
read_buf	Pointer to a buffer to receive bytes.
read_len	Number of bytes to receive.

Returns

Number of messages transferred on success, or -1 on error with errno set appropriately.