device.h File Reference

#include <stdint.h>

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Functions
uint8_t	device_exists (const char *device_name)
	Does a device file exist? More...
int32_t	get_major (const char *device)
	Gets the device major id from /proc/devices. More...
int32_t	get_param (const char *filename, const char *parameter)
	Gets a parameter from a driver param file. More...

Function Documentation

device_exists()

uint8_t device_exists

(

const char *

device_name

)

Does a device file exist?

This function provides us information regarding if a device exists on the system, it automatically prepends the /dev/ prefix if the prefix is not found in the string.

Side Effect:

File System Side Effect: This checks the file system, specifically the device tree.

Parameters

device_name

- The name of the device that we are checking if it exists or not in the /dev/ filesystem.

Returns

Returns a 0 if the device does not exist, and a 1 if it does.

Possible Failures:

Invalid File - The only way this function can fail is by not having the file in question exist.

Definition at line 30 of file device.c.

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get_major()

int32_t get_major

(

const char *

device

)

Gets the device major id from /proc/devices.

This function is used to provide us information regarding what is the major number for a particular for a device.

Side Effect:

File System Side Effect: Checks the major number of a device.

Example

get_major("nvidia-frontend") == 195

Parameters

device

- Device we want to create.

Returns

Returns the major number related to the device, or -1 in failure.

Possible Failures:

Invalid Device - In the case of an invalid device being passed it will return -1.

Device List Not Found - Device list is not found, this can occur on unsupported operating systems.

Definition at line 42 of file device.c.

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get_param()

int32_t get_param	(	const char *	filename,
		const char *	parameter
	)

Gets a parameter from a driver param file.

This function is designed to give us several parameters by which we can determine how to create the necessary character devices.

Side Effect:

File System Side Effect: Checks the device parameter file for a value.

Restriction:

This function will only work for integer parameters.

Example

get_param("/proc/driver/nvidia/params", "DeviceFileUID") == 0
get_param("/proc/driver/nvidia/params", "DeviceFileGID") == 0
get_param("/proc/driver/nvidia/params", "ResmanDebugLevel") == 4294967295

Parameters

filename	- File name for the parameter file.
parameter	- Driver parameter to search for.

Returns

Returns the integer parameter for the driver parameter we searched for, or -1 if not found.

Possible Failures:

Param File Not Found - Check if the device driver is loaded correctly.

Definition at line 71 of file device.c.

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