Hi Remy,
When I was gearing up to toss a SSD into my machine I had asked the very same question. The general concensus was that OS/2 did not need this functionality b/c the SSD device itself would be handling this function. That answer never quite sat well with me though.
I am pretty certain that in the past when these devices were new technology the drivers and/or additional utility software itself implemented this functionality along with the OS. For example, the Samsung SSD FAQ (
https://www.samsung.com/semiconductor/minisite/ssd/support/faqs-03/) clearly states the following:
Q - Does Windows XP support the TRIM feature?
A - No, only Windows 7 and above supports the TRIM feature. The Samsung SSD Magician software enables you to manually use TRIM on both Windows XP and Windows Vista.
The newer hardware on the other hand does appear to have some of this baked-in, or to be more precise it is the combination of OS FS and the hardware that makes it work. Basically, the current OSes have updated FS software which automatically notifies the SSD hardware when a particular block is no longer in use by the OS. That in turn allows the SSD firmware to "trim" accordingly, allowing the SSD firmware to implement wear levelling across it's entire storage cell body.
My experience is only based on working with the Samsung SSD: Evo850 and Pro970 (that's in my Win10 box).
Now, there is a Linux TRIM solution, it is the fstrim command which does not require the OS FS to have teh smarts to auto-trim...not sure if this requires any sort of enhanced device driver functionality, but perhaps worth looking over to see if we could port it?
Here is a link to the fstrim man page =>
http://man7.org/linux/man-pages/man8/fstrim.8.html