Is it permissible to perform Friday prayer on the upper floor of the mosque at work, given the inability to leave the premises?

Friday prayer is not valid if performed in a workplace separate from the mosque. Rather, one must follow the Friday imam, either inside the mosque or outside, provided the rows are connected. One must strive to attend it. If attendance is not possible due to the employer's refusal to grant permission, coupled with an extreme need for the job, or for the necessity of preserving life or property, then one is excused from attending it.