linux-kernel - Re: [PATCH v2] clk: Add driver for the si544 clock generator chip

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Date:   Mon, 19 Mar 2018 16:04:15 +0100
From:   Mike Looijmans <mike.looijmans@...ic.nl>
To:     Rob Herring <robh@...nel.org>
CC:     <linux-clk@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <mturquette@...libre.com>,
        <sboyd@...nel.org>, <mark.rutland@....com>
Subject: Re: [PATCH v2] clk: Add driver for the si544 clock generator chip

On 18-03-18 13:52, Rob Herring wrote:
> On Thu, Mar 15, 2018 at 12:50:08PM +0100, Mike Looijmans wrote:
>> This patch adds the driver and devicetree documentation for the
>> Silicon Labs SI544 clock generator chip. This is an I2C controlled
>> oscillator capable of generating clock signals ranging from 200kHz
>> to 1500MHz.
>>
>> Signed-off-by: Mike Looijmans <mike.looijmans@...ic.nl>
>> ---
>> v2: Add u64 cast to ls_div_bits calculation loop
>>      When ls_div_bits is non-zero, the hs_div must always be even
>>
>>   .../devicetree/bindings/clock/silabs,si544.txt     |  25 ++
>>   drivers/clk/Kconfig                                |  10 +
>>   drivers/clk/Makefile                               |   1 +
>>   drivers/clk/clk-si544.c                            | 422 +++++++++++++++++++++
>>   4 files changed, 458 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/clock/silabs,si544.txt
>>   create mode 100644 drivers/clk/clk-si544.c
>>
>> diff --git a/Documentation/devicetree/bindings/clock/silabs,si544.txt b/Documentation/devicetree/bindings/clock/silabs,si544.txt
>> new file mode 100644
>> index 0000000..eec1787
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/clock/silabs,si544.txt
>> @@ -0,0 +1,25 @@
>> +Binding for Silicon Labs 544 programmable I2C clock generator.
>> +
>> +Reference
>> +This binding uses the common clock binding[1]. Details about the device can be
>> +found in the datasheet[2].
>> +
>> +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
>> +[2] Si544 datasheet
>> +    https://www.silabs.com/documents/public/data-sheets/si544-datasheet.pdf
>> +
>> +Required properties:
>> + - compatible: One of "silabs,si514a", "silabs,si514b" "silabs,si514c" according
>> +               to the speed grade of the chip.
>> + - reg: I2C device address.
>> + - #clock-cells: From common clock bindings: Shall be 0.
>> +
>> +Optional properties:
>> + - clock-output-names: From common clock bindings. Recommended to be "si544".
> 
> What's the point if there is only 1 clock output?

I have a board with 6 of these chips, and the clock registration fails if they 
don't have unique names. Providing a clock-output-names property was the 
easiest way around it.

Should I just omit the line or change the wording to reflect the above or is 
there a better solution (maybe I can use the DT node name as clock name in the 
driver, will look into that)

> 
>> +
>> +Example:
>> +	si544: clock-generator@55 {
> 
> clock-controller@55 is the standard node name.

I'll change and post patch v3

> 
>> +		reg = <0x55>;
>> +		#clock-cells = <0>;
>> +		compatible = "silabs,si544b";
>> +	};
> 
> Otherwise, for the binding:
> 
> Reviewed-by: Rob Herring <robh@...nel.org>
> 



Kind regards,

Mike Looijmans
System Expert

TOPIC Products
Materiaalweg 4, NL-5681 RJ Best
Postbus 440, NL-5680 AK Best
Telefoon: +31 (0) 499 33 69 79
E-mail: mike.looijmans@...icproducts.com
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