From: Rob Herring <robh@kernel.org>
To: Mike Looijmans <mike.looijmans@topic.nl>
Cc: devicetree@vger.kernel.org, linux-clk@vger.kernel.org,
Conor Dooley <conor+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/2] dt-bindings: clock: fixed-clock: Add nvmem support
Date: Wed, 7 Jun 2023 16:41:55 -0600 [thread overview]
Message-ID: <20230607224155.GA107156-robh@kernel.org> (raw)
In-Reply-To: <20230605140149.16841-1-mike.looijmans@topic.nl>
On Mon, Jun 05, 2023 at 04:01:48PM +0200, Mike Looijmans wrote:
> Add bindings for a fixed-rate clock that retrieves its rate from an
> NVMEM provider. This allows to store clock settings in EEPROM or EFUSE
> or similar device.
>
> Component shortages lead to boards being shipped with different clock
> crystals, based on what was available at the time. The clock frequency
> was written to EEPROM at production time. Systems can adapt to a wide
> range of input frequencies using the clock framework, but this required
> us to patch the devicetree at runtime or use some custom driver. This
> provides a more generic solution.
>
> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
>
> ---
>
> Changes in v4:
> Use proper "if" block and add example dts
>
> Changes in v3:
> Modify fixed-clock instead of introducing nvmem-clock
>
> Changes in v2:
> Changed "fixed-clock" into "nvmem-clock" in dts example
> Add minItems:1 to nvmem-cell-names
>
> .../bindings/clock/fixed-clock.yaml | 42 ++++++++++++++++++-
> 1 file changed, 41 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/devicetree/bindings/clock/fixed-clock.yaml b/Documentation/devicetree/bindings/clock/fixed-clock.yaml
> index b0a4fb8256e2..71a5791da438 100644
> --- a/Documentation/devicetree/bindings/clock/fixed-clock.yaml
> +++ b/Documentation/devicetree/bindings/clock/fixed-clock.yaml
> @@ -12,7 +12,9 @@ maintainers:
>
> properties:
> compatible:
> - const: fixed-clock
> + enum:
> + - fixed-clock
> + - fixed-clock-nvmem
>
> "#clock-cells":
> const: 0
> @@ -26,11 +28,41 @@ properties:
> clock-output-names:
> maxItems: 1
>
> + nvmem-cells:
> + minItems: 1
> + maxItems: 2
> + description:
> + Reads clock-frequency and/or clock-accuracy from an NVMEM provider in
> + binary native integer format. The size of the NVMEM cell can be 1, 2, 4
> + or 8 bytes. If the contents of the nvmem are all zeroes or all 0xff, the
> + value reverts to the one given in the property.
> +
> + nvmem-cell-names:
> + minItems: 1
> + items:
> + - const: clock-frequency
> + - const: clock-accuracy
> +
> required:
> - compatible
> - "#clock-cells"
> - clock-frequency
>
> +allOf:
> + - if:
> + properties:
> + compatible:
> + contains:
> + const: fixed-clock-nvmem
> + then:
> + required:
> + - nvmem-cells
> + - nvmem-cell-names
> + else:
> + properties:
> + nvmem-cells: false
> + nvmem-cell-names: false
> +
> additionalProperties: false
>
> examples:
> @@ -41,4 +73,12 @@ examples:
> clock-frequency = <1000000000>;
> clock-accuracy = <100>;
> };
> + - |
> + clock {
> + compatible = "fixed-clock-nvmem";
> + #clock-cells = <0>;
> + clock-frequency = <48000000>;
If the freq comes from nvmem, why is this needed?
I think this should probably be a separate schema file as the only
other thing shared is #clock-cells.
Rob
next prev parent reply other threads:[~2023-06-07 22:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.2d27bfea-4746-444c-89f4-e5d35cb7de66@emailsignatures365.codetwo.com>
2023-06-05 14:01 ` [PATCH v4 1/2] dt-bindings: clock: fixed-clock: Add nvmem support Mike Looijmans
[not found] ` <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.126def07-6421-480e-9340-c05b31d83203@emailsignatures365.codetwo.com>
2023-06-05 14:01 ` [PATCH v4 2/2] clk: Add fixed-clock-nvmem provider Mike Looijmans
2023-06-06 8:48 ` [PATCH v4 1/2] dt-bindings: clock: fixed-clock: Add nvmem support Krzysztof Kozlowski
2023-06-07 22:41 ` Rob Herring [this message]
2023-06-22 11:41 ` Mike Looijmans
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