I write a driver based on the FreeRTOS+IO system and wondered why there is no FreeRTOS_close() API? (I also was surprised that no one asked that question before, so it must be obvious.) In my system I add in ..ioctl call to close the driver.

That is quite an old piece of code and to be honest I can’t remember. Probably just not something that would be used very often in a small embedded system where a port would be opened and then used until the device was turned off.