Re: [PATCH v3 6/7] dt-bindings: clock: meson: add A1 CPU clock controller bindings

Dmitry Rokosov
2024-06-10T12:48:45Z

On Mon, Jun 10, 2024 at 01:47:06PM +0200, Jerome Brunet wrote:
> On Mon 10 Jun 2024 at 14:18, Dmitry Rokosov <ddrokosov@salutedevices.com> wrote:
>
> > Hello Jerome,
> >
> > Thank you for the review!
> >
> > On Mon, Jun 10, 2024 at 12:04:09PM +0200, Jerome Brunet wrote:
> >> On Wed 15 May 2024 at 21:47, Dmitry Rokosov <ddrokosov@salutedevices.com> wrote:
> >>
> >> > Add the documentation and dt bindings for Amlogic A1 CPU clock
> >> > controller.
> >> >
> >> > This controller consists of the general 'cpu_clk' and two main parents:
> >> > 'cpu fixed clock' and 'syspll'. The 'cpu fixed clock' is an internal
> >> > fixed clock, while the 'syspll' serves as an external input from the A1
> >> > PLL clock controller.
> >> >
> >> > Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com>
> >> > Reviewed-by: Rob Herring <robh@kernel.org>
> >> > ---
> >> > .../bindings/clock/amlogic,a1-cpu-clkc.yaml | 64 +++++++++++++++++++
> >> > .../dt-bindings/clock/amlogic,a1-cpu-clkc.h | 19 ++++++
> >> > 2 files changed, 83 insertions(+)
> >> > create mode 100644 Documentation/devicetree/bindings/clock/amlogic,a1-cpu-clkc.yaml
> >> > create mode 100644 include/dt-bindings/clock/amlogic,a1-cpu-clkc.h
> >> >
> >> > diff --git a/Documentation/devicetree/bindings/clock/amlogic,a1-cpu-clkc.yaml b/Documentation/devicetree/bindings/clock/amlogic,a1-cpu-clkc.yaml
> >> > new file mode 100644
> >> > index 000000000000..f4958b315ed4
> >> > --- /dev/null
> >> > +++ b/Documentation/devicetree/bindings/clock/amlogic,a1-cpu-clkc.yaml
> >> > @@ -0,0 +1,64 @@
> >> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> >> > +%YAML 1.2
> >> > +---
> >> > +$id: http://devicetree.org/schemas/clock/amlogic,a1-cpu-clkc.yaml#
> >> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >> > +
> >> > +title: Amlogic A1 CPU Clock Control Unit
> >> > +
> >> > +maintainers:
> >> > + - Neil Armstrong <neil.armstrong@linaro.org>
> >> > + - Jerome Brunet <jbrunet@baylibre.com>
> >> > + - Dmitry Rokosov <ddrokosov@salutedevices.com>
> >> > +
> >> > +properties:
> >> > + compatible:
> >> > + const: amlogic,a1-cpu-clkc
> >> > +
> >> > + '#clock-cells':
> >> > + const: 1
> >> > +
> >> > + reg:
> >> > + maxItems: 1
> >> > +
> >> > + clocks:
> >> > + items:
> >> > + - description: input fixed pll div2
> >> > + - description: input fixed pll div3
> >> > + - description: input sys pll
> >> > + - description: input oscillator (usually at 24MHz)
> >>
> >> According to the documentation, fdiv5 is also an input of the CPU clock
> >> tree.
> >>
> >> That is typically the kind of things we'd prefer to get right from the
> >> beginning to avoid modifying the bindings later.
> >>
> >
> > Could you please share which documentation you are referencing? I have
> > the A113L documentation, and there is no mention of the CPU clock IP.
>
> You should get in touch with Amlogic.
>

Okay, I will double check with Amlogic and back with accurate
information.

> > I retrieved below register map from the vendor's custom driver:
> >
> > ===
> > CPUCTRL_CLK_CTRL0
> >
> > bits 1:0 - cpu_fsource_sel0
> > 0 - xtal
> > 1 - fclk_div2
> > 2 - fclk_div3
> >
> > bit 2 - cpu_fsel0
> > 0 - cpu_fsource_sel0
> > 1 - cpu_fsource_div0
> >
> > bit 3 - UNKNONWN
> >
> > bits 9:4 - cpu_fsource_div0
> > Divider value
> >
> > bit 10 - cpu_fclk
> > 0 - cpu_fsel0
> > 1 - cpu_fsel1
> >
> > bit 11 - cpu_clk
> > 0 - cpu_fclk
> > 1 - sys_pll
> >
> > bits 15:12 - UNKNONWN
> >
> > bits 17:16 - cpu_fsource_sel1
> > 0 - xtal
> > 1 - fclk_div2
> > 2 - fclk_div3
> >
> > bit 18 - cpu_fsel1
> > 0 - cpu_fsource_sel1
> > 1 - cpu_fsource_div1
> >
> > bit 19 - UNKNONWN
> >
> > bits 25:20 - cpu_fsource_div1
> > Divider value
> >
> > bits 31:26 - UNKNONWN
> > ===
> >
> > As you can see it doesn't have any other inputs except fclk_div2,
> > fclk_div3, sys_pll and xtal.
>
> You might not know what to do with it yet, still it is part of the
> documentation and should be part of the bindings too
>
> >
> >> > +
> >> > + clock-names:
> >> > + items:
> >> > + - const: fclk_div2
> >> > + - const: fclk_div3
> >> > + - const: sys_pll
> >> > + - const: xtal
> >> > +
> >> > +required:
> >> > + - compatible
> >> > + - '#clock-cells'
> >> > + - reg
> >> > + - clocks
> >> > + - clock-names
> >> > +
> >> > +additionalProperties: false
> >> > +
> >> > +examples:
> >> > + - |
> >> > + #include <dt-bindings/clock/amlogic,a1-pll-clkc.h>
> >> > + apb {
> >> > + #address-cells = <2>;
> >> > + #size-cells = <2>;
> >> > +
> >> > + clock-controller@fd000000 {
> >> > + compatible = "amlogic,a1-cpu-clkc";
> >> > + reg = <0 0xfd000080 0 0x8>;
> >>
> >> If reg is <0 0xfd000080 0 0x8> then node name should be clock-controller@fd000080
> >>
> >
> > Okay, I will fix that example in the next version.
> >
> > [...]
>
> --
> Jerome

--
Thank you,
Dmitry