Can I use a second GE port on a Cisco router to provide a redundant uplink from the switch?

I know this seems a bit of a silly question, but Cisco is not my forte, and googling has left me more confused than when I started :)

I have a HP 4208vl chassis switch (I know, not the most current gear, but it's firmware up to date (2017) and supports gigabit and otherwise suits my needs)

it's equipped with 4x modules with gigabit support, and the way I'm designing the setup is that everything that has the ability to have a redundant uplink (servers, etc.) they are getting crossed to separate switch modules, to protect against a switch module failure. I know the chassis is still a single point of failure, but it's not something I can design around at the moment.

So I've been running each server with 2 uplinks to separate modules, for example: Server 1 connects to port A5 and B5, etc.

My router is a Cisco 2921. This router has 3 on-board GE points, GE/0 is the uplink to the WAN, GE/1 is the current port running connected to the HP switch. Currently GE/2 is unused. I'd like to use this to give redundancy for the uplink, so that again, a switch module failure could keep the internet up.

I thought maybe STP was the way to go (this is already enabled on the HP anyway in RTSP mode), but it looks like the Cisco is only doing STP on the switch-ports (it also has an 8-port switch HWIC module) -- The IP for the gateway is assigned to the GE, I'm not sure how'd I'd go about setting this up?

Does anyone have a guide/blog/piece on how to set this up and understand it?