Temperature monitoring for the first gen Ryzen chips has been in the kernel for about a year. The patch for second gen is there but narrowly missed the 5.0 release window, so it should land in the first release after 5.0.
Intel is a bit faster about this but it's not like they have perfect day 1 kernel support either. i.e. temperature monitoring drivers for both first gen Ryzen and Coffee Lake landed in 4.15. At the time Ryzen was almost a year old and Coffee Lake was about half a year old.
Based on personal experience temperature monitoring on Coffee Lake worked just fine with 4.14. I'm pretty sure there hasn't been a breaking change in Intel's interface for this since at least Sandy Bridge.
I just Googled "ryzen temperature monitoring linux".
I've had a Ryzen 1700 since they first came out so I was following the Linux support for that fairly closely at the time, mostly by browsing Phoronix fairly frequently. Thankfully after a few months I didn't need to because things were working pretty well by then, other than the thermal monitoring that took quite a while to land. Linux and brand new hardware rarely seem to get along well regardless of the vendor unfortunately.
Intel is a bit faster about this but it's not like they have perfect day 1 kernel support either. i.e. temperature monitoring drivers for both first gen Ryzen and Coffee Lake landed in 4.15. At the time Ryzen was almost a year old and Coffee Lake was about half a year old.
http://lkml.iu.edu/hypermail/linux/kernel/1811.0/01237.html?...