fsp-usb

The development of this project is currently active on this Atmosphere fork.

Custom Nintendo Switch service to mount and access USB drives

Information

This sysmodule was going to be part of Atmosphere, but due to lack of motivation I stopped working on it for several months.

This is an attempt to port the old code and to fix possible bugs it had, and is still a work-in-progress.

• Not many USB drives are supported, but, in general, FAT32 and exFAT drives seem to work (otherwise, fsp-usb won't detect them)

Service

This hosts a service named fsp-usb, whose interfaces behave almost like fsp-srv's file system interfaces.

This would be it's SwIPC definition:

type fspusb::FileSystemType = enum<u8> {
    FAT12 = 1;
    FAT16 = 2;
    FAT32 = 3;
    exFAT = 4;
};

interface fspusb::Service is fsp-usb {
    
    [0] GetMountedDriveCount() -> u32 drive_count;
    [1] GetDriveFileSystemType() -> fspusb::FileSystemType fs_type;
    [2] GetDriveLabel(u32 drive_idx) -> buffer<unknown, 0x6> label;
    [3] SetDriveLabel(u32 drive_idx, buffer<unknown, 0x5> label);
    [4] OpenDriveFileSystem(u32 drive_idx) -> object<nn::fssrv::sf::IFileSystem> drive_fs;
}

• Command 3 (SetDriveLabel)'s input string shouldn't be larger than 11 characters.

• The FileSystem returned in command 4 is identical to fsp-srv's filesystems (same commands, interfaces...)

This service's results are 2002-8XXX (FS module and 8000+ error codes):

• Specific error codes:

  • 2002-8001 Invalid drive index

  • 2002-8002 Drive unavailable (accessing a filesystem/file/directory of a drive after it got unplugged)

  • 2002-8003 Drive initialization failure (used internally, never returned)

• FATFS-related results are 8100 + FATFS error, if not converted to common FS results.