While JEST216 standard exists looks like it covers only part of the protocol and hw-specific driver is still needed? ChibiOS seems to have Micron N25Q128 which is now obsolete. Open question if there are any newer Micron chips with compatible commands.
http://www.chibios.com/forum/viewtopic.php?f=38&t=3320&start=101) Common commands are common to most devices.
2) Erase/suspend is not a standard feature, its status bits are placed in different registers depending on manufacturer.
3) Program/erase status bits are not placed in a standard way, this is very annoying.
On the forum they also have a version of same driver for Cypress S25FL116/132/162 which is also obsolete. Also open question if any Cypress is compatible.
But even if we get external flash working, what is the big picture plan? Do we plan to format that chip as FAT32 and implement USB mass storage access via USB? Or else? Do we plan our totally custom persistence layer? How do we plan to access the data persisted on flash? I assume mostly logs?