Thomas Gleixner [off-list ref] writes:

On Tue, 9 Jan 2018, Michael Ellerman wrote:

Sorry, I wasn't aware about your efforts and did not cc you. I've just
queued a more generic sysfs interface for this whole mess:

No worries.

https://lkml.kernel.org/r/20180107214913.096657732@linutronix.de

It should be simple to extend for write and it would be great if all
affected architectures could share it.

As you say this has all been a bit of a mess, and as a result we already
have people running kernels with this patch, so we don't want to remove
the 'rfi_flush' file.

But we will certainly add support on powerpc for the files you have
created, in addition to 'rfi_flush'.

cheers