[RFC PATCH 14/14] mfd/macsmc: add ioctl to access smc keys

[Atharva Tiwari]

> If this isn't matching some legacy interface, then we need more
> on what these do.  Maybe they are suited to some other kernel
> interface? In particular they might need the various controls
> on how destructive they are that something like fwctl brings.
> 
> Generally an arbitrary opaque path to firmware isn't a good idea...
> 
> Jonathan

Here its required, if we write CPU/GPU Pstates and PPT to
some keys (MSTS MSPC HE0N), we can reduce the temp by 10C
And We can fix the dreaded PROCHOT signals on macs, Giving
Same temps as macOS.

But you and Sasha are right, that exposing all keys is a
bad idea, so i have restricted writing to some keys only.