Thank you for contacting Cypress Semiconductor.
Could you please clarify your question? As per my understanding, you are saying that the driver by ST does not extend support for S25FL256S and it needs to be fixed. I would like to suggest you to contact ST Microelectronics for that.
I would also like to inform you that Cypress has its own low level driver for its serial flash devices. I am attaching the driver with my response. You can go through it and use it in you project if you want.
Please let me know if you have any more queries.
slld_v16.2.1.zip 6.8 MB
Sorry, that was not a question.
I wanted to share a solution to the problem.