Login authentication in codeigniter

Question

when a person want to log in but he/she failed into first attempt then captcha will show and he/she remains only 3 tries but he/she failed into all of there reaming attempts then on the particular ip login will be block for some time how it will be possible into codeigniter

this is my code

function login() {
    $this->form_validation->set_rules('username', 'Username', 'trim|required');
    $this->form_validation->set_rules('password', 'Password', 'trim|required|md5');
    //$this->session->unset_userdata('count');
    if($this->session->userdata('count')) {

        $this->form_validation->set_rules('captcha', 'Captcha', 'required|callback_recaptcha_validation');
        $this->session->unset_userdata('count');
    }

    if ($this->form_validation->run() == TRUE) {
        $checkAdminLoginDeatils = $this->admin_model->adminLogin();
        if ($checkAdminLoginDeatils == false) {
            $val='0';
            $val=$this->session->set_userdata('validate','0');
            $val=$val+1;
            $ip_address = $this->input->ip_address();
            $record = $this->db->where('IP', $ip_address)->get('LoginAttempts')->row();
            $this->session->set_userdata('count', '1');
            $vals = array(
                    'img_path'   => './captcha/',
                    'img_url'    =>  base_url().'/captcha/'
            );

            $cap = create_captcha($vals);

            $captcha = array(
                    'captcha_time'  => $cap['time'],
                    'ip_address'    => $this->input->ip_address(),
                    'word'   => $cap['word']
            );

            $data['cap']=$cap;
            $this->session->set_userdata('message', 'Invalid username or password');
            $this->db->select('*');
            $this->db->where('IP',$this->input->ip_address());
            $query=$this->db->get('LoginAttempts');
           if($query->num_rows() == 1) {
                $this->db->set('LastLogin',time());
                if(isset ($val))
                    $this->db->set('Attempts',$val);
                $this->db->where('IP', $this->input->ip_address());
                $result=$this->db->update('LoginAttempts');
            }
            else {
                $insert = array(
                        'LastLogin' => time(),
                        'Attempts' => $val,
                        'IP'    => $this->input->ip_address()
                );


                $query = $this->db->insert_string('LoginAttempts', $insert);
                $this->db->query($query);
            }
            //$time=now();


            $expiration = time()-7200; // Two hour limit
            $this->db->query("DELETE FROM LoginAttempts WHERE LastLogin < ".$expiration);
        } else {
            redirect('admin/admin/dashboard');
        }
    }