Device System
[RT-Thread Kernel API]

Functions
rt_device_t	rt_device_find (const char *name)
rt_err_t	rt_device_register (rt_device_t dev, const char *name, rt_uint8_t flags)
rt_err_t	rt_device_unregister (rt_device_t dev)
rt_err_t	rt_device_init_all (void)
rt_err_t	rt_device_open (rt_device_t dev)
rt_err_t	rt_device_close (rt_device_t dev)
rt_err_t	rt_device_read (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
rt_err_t	rt_device_write (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size)
rt_err_t	rt_device_control (rt_device_t dev, rt_uint8_t cmd, void *arg)

---

Detailed Description

The Device System is designed as simple and minimum layer to help communication between applications and drivers.

The Device System provide five interfaces to driver:

• open, open a device
• close, close a device
• read, read some data from a device
• write, write some data to a device
• control, send some control command to a device

---

Function Documentation

rt_err_t rt_device_close

(

rt_device_t

dev

)

This function will close a device

Parameters:

dev

the pointer of device driver structure

Returns:

the result

rt_err_t rt_device_control	(	rt_device_t	dev,
		rt_uint8_t	cmd,
		void *	arg
	)

This function will perform a variety of control functions on devices.

Parameters:

	dev	the pointer of device driver structure
	cmd	the command sent to device
	arg	the argument of command

Returns:

the result

rt_device_t rt_device_find

(

const char *

name

)

This function finds a device driver by specified name.

Parameters:

name

the device driver's name

Returns:

the registered device driver on successful, or RT_NULL on failure.

rt_err_t rt_device_init_all

(

void

)

This function initializes all registered device driver

Returns:

the error code, RT_EOK on successfully.

rt_err_t rt_device_open

(

rt_device_t

dev

)

This function will open a device

Parameters:

dev

the pointer of device driver structure

Returns:

the result

rt_err_t rt_device_read	(	rt_device_t	dev,
		rt_off_t	pos,
		void *	buffer,
		rt_size_t	size
	)

This function will read some data from a device.

Parameters:

	dev	the pointer of device driver structure
	pos	the position of reading
	buffer	the data buffer to save read data
	size	the size of buffer

Returns:

the actually read size on successful, otherwise negative returned.

rt_err_t rt_device_register	(	rt_device_t	dev,
		const char *	name,
		rt_uint8_t	flags
	)

This function registers a device driver with specified name.

Parameters:

	dev	the pointer of device driver structure
	name	the device driver's name
	flags	the flag of device

Returns:

the error code, RT_EOK on initialization successfully.

rt_err_t rt_device_unregister

(

rt_device_t

dev

)

This function removes a previouly registered device driver

Parameters:

dev

the pointer of device driver structure

Returns:

the error code, RT_EOK on successfully.

rt_err_t rt_device_write	(	rt_device_t	dev,
		rt_off_t	pos,
		const void *	buffer,
		rt_size_t	size
	)

This function will write some data to a device.

Parameters:

	dev	the pointer of device driver structure
	pos	the position of written
	buffer	the data buffer to be written to device
	size	the size of buffer

Returns:

the actually written size on successful, otherwise negative returned.