Well you have a few options. 1st, with BootOs/lv2patcher you can install linux to an external hdd and run it via a gameos app, this will work with any ps3.
If you have a fat ps3 with a 16mb nor (or any slim) there is a method (work in progress, it works but some people have issues with it) to get linux installed on the internal hdd, and run it via gameos apps. If you have a fat ps3 with 256mb nand, there *may* be a way to get linux installed to the internal hdd, but I'm not going to go into that because I can't test it atm.
So yeah, post your model (sticker on back of console CECH*****), we can find out if it has nand/nor, and tell you your options, there are already a few stickied topics in the section.
This seems to list the models and will tell you if you have nand/nor.
List of PS3 NAND sizes by model #
STOP! Before you ask questions... READ the first post! RTFFP = Read The F*cking First Post
Yes, A 3.55 "jb" (cfw) is available, no >3.55 "jb" or cfw yet.
Yes, A 3.55 downgrade is available. But not to lower than stock firmware! (What it came with)
No >3.55 downgrade is out there yet.