Re: [PATCH v5 2/7] clk: qcom: Add generic clkref_en support

[Qiang Yu]

On Sat, Jun 13, 2026 at 03:46:17PM -0700, Stephen Boyd wrote:
> Quoting Qiang Yu (2026-06-02 01:02:18)
> > Before XO refclk is distributed to PCIe/USB/eDP PHYs, it passes through
> > a QREF block. QREF is powered by dedicated LDO rails, and the clkref_en
> > register controls whether refclk is gated through to the PHY side.
> > 
> > These clkref controls are different from typical GCC branch clocks:
> > - only a single enable bit is present, without branch-style config bits
> > - regulators must be voted before enable and unvoted after disable
> > 
> > Model this as a dedicated clk_ref clock type with custom clk_ops instead
> > of reusing struct clk_branch semantics.
> > 
> > Also provide a common registration/probe API so the same clkref model
> > can be reused regardless of where clkref_en registers are placed, e.g.
> > TCSR on glymur and TLMM on SM8750.
> > 
> > Signed-off-by: Qiang Yu <qiang.yu@xxxxxxxxxxxxxxxx>
> > ---
> [...]
> > diff --git a/include/linux/clk/qcom.h b/include/linux/clk/qcom.h
> > new file mode 100644
> > index 000000000000..09e2e3178cfb
> > --- /dev/null
> > +++ b/include/linux/clk/qcom.h
> 
> Why are we making this file in linux/clk when only drivers/clk/qcom/ is
> going to use it? We can have some qref.h header in the qcom clk driver
> area.

The header is placed under include/linux/clk/ intentionally for reuse
across different drivers. On glymur the clkref_en registers are in TCSR,
but on SM8750 they are in TLMM, so the registration API needs to be
accessible from outside drivers/clk/qcom/. Keeping it under
include/linux/clk/ allows the TLMM driver to call qcom_clk_ref_probe().

See this earlier attempt for context:
https://lore.kernel.org/linux-arm-msm/20260202-topic-8750_tcsr-v1-4-cd7e6648c64f@xxxxxxxxxxxxxxxx/

- Qiang Yu