Which ever role you want to allow to login give the role the permission.
Drupal 6
Please change the permission to an appropriate one. This is just for test purpose.
function modulename_perm() {
return array('allow modulename login');
}
function modulename_user($op, &$edit, &$account, $category = NULL) {
if ($op == 'login') {
if (user_access('allow modulename login') == FALSE) {
drupal_set_message('Member logins have been temporarily disabled. Please try again later.', 'warning');
user_logout();
exit;
}
}
}
DRUPAL 7
function modulename_permission() {
return array(
'allow modulename login' => array(
'title' => t('allow modulename login'),
'description' => t('allow modulename login.'),
),
);
}
function modulename_user_login(&$edit, $account) {
if (user_access('allow modulename login') == FALSE) {
drupal_set_message('Member logins have been temporarily disabled. Please try again later.', 'warning');
user_logout();
exit;
}
}