The Qualcomm TCSR is some top level glue between multiple IP blocks,
both for doing configuration of said IP blocks, some IPC between
them (mostly between multiple execution environments - eg trustzone
and non-TZ), and interrupt status bits for them.
However, for the IPQ4018/IPQ4019, it only is used as a small subset
of IP block configuration. As for what it actually gets used as
for other Qualcomm chipsets? Well, that'll have to wait.
It's a bit of a mess in linux and openwrt. See, every different
SoC support branch ends up with some different TCSR code for it.
So instead, I'm going to land a single TCSR driver that I'm going
to use for the IPQ4018/IPQ4019. When I add the next chipset, I'll
figure out how to organise things so there's a single TCSR driver
that works for multiple platforms.