Descriptor API
[Level 1 API]

Collaboration diagram for Descriptor API:

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Detailed Description

This is the API interface used to fill and use Analogy device descriptor structure

Functions
int	a4l_open (a4l_desc_t *dsc, const char *fname)
	Open an Analogy device and basically fill the descriptor.
int	a4l_close (a4l_desc_t *dsc)
	Close the Analogy device related with the descriptor.
int	a4l_fill_desc (a4l_desc_t *dsc)
	Fill the descriptor with subdevices, channels and ranges data.
int	a4l_get_subdinfo (a4l_desc_t *dsc, unsigned int subd, a4l_sbinfo_t **info)
	Get an information structure on a specified subdevice.
int	a4l_get_chinfo (a4l_desc_t *dsc, unsigned int subd, unsigned int chan, a4l_chinfo_t **info)
	Get an information structure on a specified channel.
int	a4l_get_rnginfo (a4l_desc_t *dsc, unsigned int subd, unsigned int chan, unsigned int rng, a4l_rnginfo_t **info)
	Get an information structure on a specified range.

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Function Documentation

int a4l_close

(

a4l_desc_t *

dsc

)

Close the Analogy device related with the descriptor.

Parameters:

[in]

dsc

Device descriptor

Returns:

0 on success. Otherwise:

• -EINVAL is returned if some argument is missing or wrong; the the dsc pointer should be checked; check also the kernel log ("dmesg")

References a4l_sys_close(), and a4l_descriptor::fd.

int a4l_fill_desc

(

a4l_desc_t *

dsc

)

Fill the descriptor with subdevices, channels and ranges data.

Parameters:

[in]

dsc

Device descriptor partly filled by a4l_open().

Returns:

0 on success. Otherwise:

• -EINVAL is returned if some argument is missing or wrong; the the dsc pointer should be checked; check also the kernel log ("dmesg")
• -EFAULT is returned if a user <-> kernel transfer went wrong

References A4L_CPLX_DESC, a4l_sys_desc(), a4l_descriptor::fd, and a4l_descriptor::magic.

int a4l_get_chinfo	(	a4l_desc_t *	dsc,
		unsigned int	subd,
		unsigned int	chan,
		a4l_chinfo_t **	info
	)

Get an information structure on a specified channel.

Parameters:

[in]	dsc	Device descriptor filled by a4l_open() and a4l_fill_desc()
[in]	subd	Subdevice index
[in]	chan	Channel index
[out]	info	Channel information structure

Returns:

0 on success. Otherwise:

• -EINVAL is returned if some argument is missing or wrong; subd, chan and the dsc pointer should be checked; check also the kernel log ("dmesg"); WARNING: a4l_fill_desc() should be called before using a4l_get_chinfo()

References a4l_descriptor::magic, a4l_descriptor::nb_subd, and a4l_descriptor::sbdata.

Referenced by a4l_find_range().

int a4l_get_rnginfo	(	a4l_desc_t *	dsc,
		unsigned int	subd,
		unsigned int	chan,
		unsigned int	rng,
		a4l_rnginfo_t **	info
	)

Get an information structure on a specified range.

Parameters:

[in]	dsc	Device descriptor filled by a4l_open() and a4l_fill_desc()
[in]	subd	Subdevice index
[in]	chan	Channel index
[in]	rng	Range index
[out]	info	Range information structure

Returns:

0 on success. Otherwise:

• -EINVAL is returned if some argument is missing or wrong; subd, chan, rng and the dsc pointer should be checked; check also the kernel log ("dmesg"); WARNING: a4l_fill_desc() should be called before using a4l_get_rnginfo()

References a4l_descriptor::magic, a4l_descriptor::nb_subd, and a4l_descriptor::sbdata.

Referenced by a4l_find_range().

int a4l_get_subdinfo	(	a4l_desc_t *	dsc,
		unsigned int	subd,
		a4l_sbinfo_t **	info
	)

Get an information structure on a specified subdevice.

Parameters:

[in]	dsc	Device descriptor filled by a4l_open() and a4l_fill_desc()
[in]	subd	Subdevice index
[out]	info	Subdevice information structure

Returns:

0 on success. Otherwise:

• -EINVAL is returned if some argument is missing or wrong; subd and the dsc pointer should be checked; check also the kernel log ("dmesg"); WARNING: a4l_fill_desc() should be called before using a4l_get_subdinfo().

References a4l_descriptor::magic, a4l_descriptor::nb_subd, and a4l_descriptor::sbdata.

Referenced by a4l_sync_dio().

int a4l_open	(	a4l_desc_t *	dsc,
		const char *	fname
	)

Open an Analogy device and basically fill the descriptor.

Parameters:

[out]	dsc	Device descriptor
[in]	fname	Device name

Returns:

0 on success. Otherwise:

• -EINVAL is returned if some argument is missing or wrong; the fname and the dsc pointer should be checked; check also the kernel log ("dmesg")
• -EFAULT is returned if a user <-> kernel transfer went wrong

References A4L_BSC_DESC, a4l_sys_close(), a4l_sys_desc(), a4l_sys_open(), and a4l_descriptor::fd.