What is arm,amba-primecell?

Hi,

I stumbled into a compatible property valued arm,amba-primecell and
wondered what it means. Thus I started looking in the kernel source:

linux$ git grep arm,amba-primecell v5.1-rc2
Documentation/devicetree/usage-model.txt:be too invasive.  If a node is compatible with "arm,amba-primecell", then
arch/arm/boot/dts/nspire.dtsi:                          compatible = "arm,amba-primecell";
linux$

Such rare usage seems strange. Is this a mistake? Is it that these two
files need a s/arm,amba-primecell/arm,primecell/?

Helmut