Add and use a generic version of devmem_is_allowed()

[Palmer Dabbelt]

On Tue, 28 Jul 2020 17:00:30 PDT (-0700), mcgrof at kernel.org wrote:
> On Thu, Jul 09, 2020 at 02:19:20PM -0700, Palmer Dabbelt wrote:
>> As part of adding STRICT_DEVMEM support to the RISC-V port, Zong provided an
>> implementation of devmem_is_allowed() that's exactly the same as the version in
>> a handful of other ports.  Rather than duplicate code, I've put a generic
>> version of this in lib/ and used it for the RISC-V port.
>>
>> I've put those first two patches on riscv/for-next, which I'm targeting for 5.9
>> (though this is the first version, so they're unreviewed).  The other three
>> obviously depend on the first one going on, but I'm not putting them in the
>> RISC-V tree as I don't want to step on anyone's toes.  If you want me to take
>> yours along with the others then please say something, as otherwise I'll
>> probably forget.
>>
>> I've put the whole thing at
>> ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/palmer/linux.git -b
>> generic-devmem .
>
> Reviewed-by: Luis Chamberlain <mcgrof at kernel.org>

Thanks.  Davoid pointed out that I forgot about this, so I just rebased it onto
5.9 and merged it into my for-next.