The device ID functions are:
Allocate a device ID structure
Free a device ID structure
Register a device ID
Unregister a device ID
Compare two device IDs
Return the size of a device ID
Validate a device ID
Encode a device ID and minor_name into a null-terminated ASCII string; return a pointer to that string
Decode the device ID and minor_name from a previously encoded string; allocate and return pointers to the extracted parts
Free all strings returned by the ddi_devid_* functions