Tex. Lab. Code § 52.061

A public or private employer may not prohibit an employee who holds a license to carry a handgun under Subchapter H, Chapter 411, Government Code, who otherwise lawfully possesses a firearm, or who lawfully possesses ammunition from transporting or storing a firearm or ammunition the employee is authorized by law to possess in a locked, privately owned motor vehicle in a parking lot, parking garage, or other parking area the employer provides for employees.