Due to my dictionary
来られる would be the passive as well as potential form.
Potential form is clear:
来られる? -> Can you come?
But I have great trouble imagining a sentence of 来られる in the passive version. I suppose the entry in my dictionary or at じしょ see under the link to the left "show inflections", was generated in a generic way or relates to compund verbs (see the end of my post), without considering whether or not the inflection is logically possible.
At least I am unable to come up with a passive form "to come" in English (and German and Slovak).
Furthermore, as discussed here: What forms of verbs (potential or passive) are more frequent in Japanese? English seems to use passive voice more often than Japanese.
Nevertheless, I even googled for a possible passive voice sentence in English, and found this explanation by Martin Brilliant, which is to me, a non-linguist, totally plausible:
What is the passive voice of "I am coming"?
It doesn’t have one. What? You say it does? Then “am” must be a transitive verb, and “coming” must be a noun acting as its object. I have trouble thinking about that, so I’m going to replace those words with words that I recognize as a transitive verb and a noun. The passive voice of “I see water” is “Water is seen,” or “Water is seen by me.” So the passive voice of “I am coming” must be “Coming is been,” or “Coming is been by me.” If you think that’s nonsense, then rethink your idea that there’s a passive voice of “I am coming.”
But I would like to make sure that every time I come across 来られる or 来れる I can automatically consider it to be the potential form.
I am explicitly not considering compund verbs such as 連れて来る or 持って来る. Because even though they end with 来る they have an object and are thus transitive, so the passive voice of them in Japanese should not be grammatically impossible (even though they might sound weird, but I have not yet progressed so far as to be able to discern that.)
Thanks a lot!