Man page 9 : debugfs_create_u32

debugfs_create_u32 - create a debugfs file that is used to read and write an unsigned 32-bit value

struct dentry * debugfs_create_u32(const char *  name , umode_t  mode , struct dentry *  parent , u32 *  value );

name
    a pointer to a string containing the name of the file to create.

mode
    the permission that the file should have

parent
    a pointer to the parent dentry for this file. This should be a directory dentry if set. If this parameter is NULL, then the file will be created in the root of the debugfs filesystem.

value
    a pointer to the variable that the file should read to and write from.

This function creates a file in debugfs with the given name that contains the value of the variable value. If the mode variable is so set, it can be read from, and written to.

This function will return a pointer to a dentry if it succeeds. This pointer must be passed to the debugfs_remove function when the file is to be removed (no automatic cleanup happens if your module is unloaded, you are responsible here.) If an error occurs, NULL will be returned.

If debugfs is not enabled in the kernel, the value -ENODEV will be returned. It is not wise to check for this value, but rather, check for NULL or !NULL instead as to eliminate the need for #ifdef in the calling code.