linux-kernel - Re: [PATCH v2] mfd: syscon: add child device support

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Date:	Mon, 17 Nov 2014 10:18:30 +0800
From:	Flora Fu <flora.fu@...iatek.com>
To:	Philipp Zabel <p.zabel@...gutronix.de>
CC:	Rob Herring <robh+dt@...nel.org>, Lee Jones <lee.jones@...aro.org>,
	Arnd Bergmann <arnd@...db.de>, Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<kernel@...gutronix.de>, <srv_heupstream@...iatek.com>
Subject: Re: [PATCH v2] mfd: syscon: add child device support

Hi, Philipp,

How is the status of syscon patch in
https://lkml.org/lkml/2014/5/27/422 ?
Will this patch be accepted in feature release 3.19?

Thanks,
Flora

On Mon, 2014-11-03 at 10:16 +0100, Philipp Zabel wrote:
> For devices which have a complete register for themselves, it is possible to
> place them next to the syscon device with overlapping reg ranges. The same is
> not possible for devices which only occupy bitfields in registers shared with
> other users.
> For devices that are completely controlled by bitfields in the syscon address
> range, such as multiplexers or voltage regulators, allow to put child devices
> into the syscon device node.
> 
> Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
> ---
> Changes since v1:
>  - Reworded binding documentation to allow #size-cells = <1>, which is useful
>    for syscon children that are controlled through a (possibly shared) register
>    range.
> ---
>  Documentation/devicetree/bindings/mfd/syscon.txt | 13 +++++++++++++
>  drivers/mfd/syscon.c                             |  3 +++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mfd/syscon.txt b/Documentation/devicetree/bindings/mfd/syscon.txt
> index fe8150b..0c6b497 100644
> --- a/Documentation/devicetree/bindings/mfd/syscon.txt
> +++ b/Documentation/devicetree/bindings/mfd/syscon.txt
> @@ -9,12 +9,25 @@ using a specific compatible value), interrogate the node (or associated
>  OS driver) to determine the location of the registers, and access the
>  registers directly.
>  
> +Optionally, devices that are controlled exclusively through syscon registers,
> +or even bitfields in shared syscon registers, can also be added as child nodes
> +to the syscon device node. These devices can implicitly assume their parent
> +node is a syscon provider without referencing it explicitly via phandle.
> +In this case, the syscon node should have #address-cells = <1> and
> +#size-cells = <0> or <1> and no ranges property.
> +
>  Required properties:
>  - compatible: Should contain "syscon".
>  - reg: the register region can be accessed from syscon
>  
> +Optional properties:
> +- #address-cells: Should be 1.
> +- #size-cells: Should be 0 or 1.
> +
>  Examples:
>  gpr: iomuxc-gpr@...e0000 {
> +	#address-cells = <1>;
> +	#size-cells = <0>;
>  	compatible = "fsl,imx6q-iomuxc-gpr", "syscon";
>  	reg = <0x020e0000 0x38>;
>  };
> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
> index ca15878..38da178 100644
> --- a/drivers/mfd/syscon.c
> +++ b/drivers/mfd/syscon.c
> @@ -155,6 +155,9 @@ static int syscon_probe(struct platform_device *pdev)
>  
>  	dev_dbg(dev, "regmap %pR registered\n", res);
>  
> +	if (!of_device_is_compatible(pdev->dev.of_node, "simple-bus"))
> +		of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
> +
>  	return 0;
>  }
>  


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