S70GL02GS is a dual die stack of two S29GL01GS devices. We do not have a low level driver (LLD) for S70GL02GS, but you can refer the LLD for S29GL01GS available at: https://www.cypress.com/documentation/software-and-drivers/low-level-driver-nor-flash?source=search&cat=software_tools to understand how PPB bits are managed. Please refer the source files inside the folder "device_specific\S29GLxxxS".
Please feel free to ask if you have any other related queries.
Thanks and Regards,