Man page 9 : subsys_find_device_by_id

subsys_find_device_by_id - find a device with a specific enumeration number

struct device * subsys_find_device_by_id(struct bus_type *  subsys , unsigned int  id , struct device *  hint );

subsys
    subsystem

id
    index AqidAq in struct device

hint
    device to check first

Check the hintAqs next object and if it is a match return it directly, otherwise, fall back to a full list search. Either way a reference for the returned object is taken.