Re: [PATCH v11 1/4] firmware: qcom: scm: provide a read-modify-write function

[Mukesh Ojha]

On 1/9/2024 6:44 PM, Linus Walleij wrote:
> On Mon, Jan 8, 2024 at 4:28 PM Mukesh Ojha <quic_mojha@xxxxxxxxxxx> wrote:
>
> > It was realized by Srinivas K. that there is a need of
> > read-modify-write scm exported function so that it can
> > be used by multiple clients.
> >
> > Let's introduce qcom_scm_io_rmw() which masks out the bits
> > and write the passed value to that bit-offset.
> (...)
> > +int qcom_scm_io_rmw(phys_addr_t addr, unsigned int mask, unsigned int val)
> > +{
> > +       unsigned int old, new;
> > +       int ret;
> > +
> > +       if (!__scm)
> > +               return -EINVAL;
> > +
> > +       spin_lock(&__scm->lock);
> > +       ret = qcom_scm_io_readl(addr, &old);
> > +       if (ret)
> > +               goto unlock;
> > +
> > +       new = (old & ~mask) | (val & mask);
> > +
> > +       ret = qcom_scm_io_writel(addr, new);
> > +unlock:
> > +       spin_unlock(&__scm->lock);
> > +       return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(qcom_scm_io_rmw);
>
> This looks a lot like you are starting to re-invent regmaps
> regmap_update_bits().
>
> If you are starting to realize you need more and more of
> regmap, why not use regmap and its functions?

I think, this discussion has happened already ..

https://lore.kernel.org/lkml/CACRpkdb95V5GC81w8fiuLfx_V1DtWYpO33FOfMnArpJeC9SDQA@xxxxxxxxxxxxxx/

-Mukesh

> Yours,
> Linus Walleij