On 2/17/2024 12:01 AM, Bjorn Andersson wrote:
On Tue, Jan 09, 2024 at 02:34:10PM +0100, Linus Walleij wrote:
On Tue, Jan 9, 2024 at 2:24 PM Mukesh Ojha <quic_mojha@xxxxxxxxxxx> wrote:
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/
That discussion ended with:
[Bjorn]
We'd still need qcom_scm_io_readl() and qcom_scm_io_writel() exported to
implement the new custom regmap implementation - and the struct
regmap_config needed in just pinctrl-msm alone would be larger than the
one function it replaces.
When you add more and more accessors the premise starts to
change, and it becomes more and more of a reimplementation.
It may be time to actually fix this.
Thought I had replied to this already, did we discuss this previously as
well?
My concern with expressing this as a regmap is that from the provider's
point of view, the regmap would span the entire 32-bit address space.
I'm guessing that there's something on the other side limiting what
subregions are actually accessible for each platform/firmware
configuration, but I'm not convinced that regmap a good abstraction...
To add more to it, in current series, we are just accessing single
register for read/write and using regmap for this looks overkill to
me.
-Mukesh
Regards,
Bjorn
Yours,
Linus Walleij
