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SubjectRe: [PATCH v3 04/10] Documentations: dt-bindings: Add a document of PECI adapter driver for Aspeed AST24xx/25xx SoCs
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Hi Joel,

On 4/11/2018 4:52 AM, Joel Stanley wrote:
> On 11 April 2018 at 04:02, Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> wrote:
>> This commit adds a dt-bindings document of PECI adapter driver for Aspeed
>
> We try to capitalise ASPEED.
>

Got it. Will capitalize all Aspeed words.

>> AST24xx/25xx SoCs.
>> ---
>> .../devicetree/bindings/peci/peci-aspeed.txt | 60 ++++++++++++++++++++++
>> 1 file changed, 60 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/peci/peci-aspeed.txt
>>
>> diff --git a/Documentation/devicetree/bindings/peci/peci-aspeed.txt b/Documentation/devicetree/bindings/peci/peci-aspeed.txt
>> new file mode 100644
>> index 000000000000..4598bb8c20fa
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/peci/peci-aspeed.txt
>> @@ -0,0 +1,60 @@
>> +Device tree configuration for PECI buses on the AST24XX and AST25XX SoCs.
>> +
>> +Required properties:
>> +- compatible : Should be "aspeed,ast2400-peci" or "aspeed,ast2500-peci"
>> + - aspeed,ast2400-peci: Aspeed AST2400 family PECI
>> + controller
>> + - aspeed,ast2500-peci: Aspeed AST2500 family PECI
>> + controller
>> +- reg : Should contain PECI controller registers location and
>> + length.
>> +- #address-cells : Should be <1>.
>> +- #size-cells : Should be <0>.
>> +- interrupts : Should contain PECI controller interrupt.
>> +- clocks : Should contain clock source for PECI controller.
>> + Should reference clkin.
>
> Are you sure that this is driven by clkin? Most peripherals on the
> Aspeed are attached to the apb, so should reference that clock.
>

According to the datasheet, PECI controller module is attached to apb
but its clock source is the 24MHz external clock.

>> +- clock_frequency : Should contain the operation frequency of PECI controller
>> + in units of Hz.
>> + 187500 ~ 24000000
>
> Can you explain why you need both the parent clock and this frequency
> to be specified?
>

Based on this setting, driver code makes clock divisor value to set
operation clock of PECI controller which is adjustable.

>> +
>> +Optional properties:
>> +- msg-timing-nego : Message timing negotiation period. This value will
>
> Perhaps msg-timing-period? Or just msg-timing?
>

Will use msg-timing instead.

>> + determine the period of message timing negotiation to be
>> + issued by PECI controller. The unit of the programmed
>> + value is four times of PECI clock period.
>> + 0 ~ 255 (default: 1)
>> +- addr-timing-nego : Address timing negotiation period. This value will
>> + determine the period of address timing negotiation to be
>> + issued by PECI controller. The unit of the programmed
>> + value is four times of PECI clock period.
>> + 0 ~ 255 (default: 1)
>> +- rd-sampling-point : Read sampling point selection. The whole period of a bit
>> + time will be divided into 16 time frames. This value will
>> + determine the time frame in which the controller will
>> + sample PECI signal for data read back. Usually in the
>> + middle of a bit time is the best.
>> + 0 ~ 15 (default: 8)
>> +- cmd_timeout_ms : Command timeout in units of ms.
>> + 1 ~ 60000 (default: 1000)
>> +
>> +Example:
>> + peci: peci@1e78b000 {
>> + compatible = "simple-bus";
>> + #address-cells = <1>;
>> + #size-cells = <1>;
>> + ranges = <0x0 0x1e78b000 0x60>;
>> +
>> + peci0: peci-bus@0 {
>> + compatible = "aspeed,ast2500-peci";
>> + reg = <0x0 0x60>;
>> + #address-cells = <1>;
>> + #size-cells = <0>;
>> + interrupts = <15>;
>> + clocks = <&clk_clkin>;
>> + clock-frequency = <24000000>;
>> + msg-timing-nego = <1>;
>> + addr-timing-nego = <1>;
>> + rd-sampling-point = <8>;
>> + cmd-timeout-ms = <1000>;
>> + };
>> + };
>> --
>> 2.16.2
>>

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