linux-kernel - Re: [PATCH v3 04/10] Documentations: dt-bindings: Add a document of PECI adapter driver for Aspeed AST24xx/25xx SoCs

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Message-ID: <CACPK8XcfrheC+UDB7mLPkgPRCuk8f+P830NG+cy2v6F_PJvUTw@mail.gmail.com>
Date:   Wed, 11 Apr 2018 21:22:23 +0930
From:   Joel Stanley <joel@....id.au>
To:     Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>,
        Rob Herring <robh+dt@...nel.org>,
        linux-aspeed@...ts.ozlabs.org, Ryan Chen <ryan_chen@...eedtech.com>
Cc:     Alan Cox <alan@...ux.intel.com>, Andrew Jeffery <andrew@...id.au>,
        Andrew Lunn <andrew@...n.ch>,
        Andy Shevchenko <andriy.shevchenko@...el.com>,
        Arnd Bergmann <arnd@...db.de>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Fengguang Wu <fengguang.wu@...el.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Haiyue Wang <haiyue.wang@...ux.intel.com>,
        James Feist <james.feist@...ux.intel.com>,
        Jason M Biils <jason.m.bills@...ux.intel.com>,
        Jean Delvare <jdelvare@...e.com>,
        Julia Cartwright <juliac@....teric.us>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        Milton Miller II <miltonm@...ibm.com>,
        Pavel Machek <pavel@....cz>,
        Randy Dunlap <rdunlap@...radead.org>,
        Stef van Os <stef.van.os@...drive-technologies.com>,
        Sumeet R Pawnikar <sumeet.r.pawnikar@...el.com>,
        Vernon Mauery <vernon.mauery@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-doc@...r.kernel.org, devicetree <devicetree@...r.kernel.org>,
        linux-hwmon@...r.kernel.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>
Subject: Re: [PATCH v3 04/10] Documentations: dt-bindings: Add a document of
 PECI adapter driver for Aspeed AST24xx/25xx SoCs

On 11 April 2018 at 04:02, Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com> wrote:
> This commit adds a dt-bindings document of PECI adapter driver for Aspeed

We try to capitalise ASPEED.

> 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.

> +- 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?

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

Perhaps msg-timing-period? Or just msg-timing?

> +                     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@...8b000 {
> +               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
>