linux-kernel - Re: [PATCH v6 1/2] DT: hwspinlock: Add binding documentation for Qualcomm hwmutex

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Date:	Thu, 16 Apr 2015 12:52:38 +0100
From:	Mark Rutland <mark.rutland@....com>
To:	Bjorn Andersson <bjorn.andersson@...ymobile.com>
Cc:	Rob Herring <robh+dt@...nel.org>, Pawel Moll <Pawel.Moll@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Ohad Ben-Cohen <ohad@...ery.com>,
	Kumar Gala <galak@...eaurora.org>, Suman Anna <s-anna@...com>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	Jeffrey Hugo <jhugo@...eaurora.org>,
	Andy Gross <agross@...eaurora.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 1/2] DT: hwspinlock: Add binding documentation for
 Qualcomm hwmutex

On Fri, Feb 27, 2015 at 10:30:16PM +0000, Bjorn Andersson wrote:
> Add binding documentation for the Qualcomm Hardware Mutex.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...ymobile.com>
> ---
> 
> I think the conclusion on the dt binding discussion for hwspinlocks was that
> we're down to having the #hwlock-cells intact. So this version includes that,
> but non of the other previously discussed properties.
> 
> Changes since v5:
> - Extracted the dt binding documentation into a separate patch
> - Moved the driver to consume a syscon
> - Dropped previously suggested generic hwlock dt bindings
> 
>  .../devicetree/bindings/hwlock/qcom-hwspinlock.txt | 39 ++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwlock/qcom-hwspinlock.txt
> 
> diff --git a/Documentation/devicetree/bindings/hwlock/qcom-hwspinlock.txt b/Documentation/devicetree/bindings/hwlock/qcom-hwspinlock.txt
> new file mode 100644
> index 0000000..28ade7d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwlock/qcom-hwspinlock.txt
> @@ -0,0 +1,39 @@
> +Qualcomm Hardware Mutex Block:
> +
> +The hardware block provides mutexes utilized between different processors on
> +the SoC as part of the communication protocol used by these processors.
> +
> +- compatible:
> +	Usage: required
> +	Value type: <string>
> +	Definition: must be one of:
> +		    "qcom,sfpb-mutex",
> +		    "qcom,tcsr-mutex"
> +
> +- syscon:
> +	Usage: required
> +	Value type: <prop-encoded-array>
> +	Definition: one cell containing:
> +		    syscon phandle
> +		    offset of the hwmutex block within the syscon
> +		    stride of the hwmutex registers
> +
> +- #hwlock-cells:
> +	Usage: required
> +	Value type: <u32>
> +	Definition: must be 1, the specified cell represent the lock id
> +		    (hwlock standard property, see hwlock.txt)

I guess that this is a linear ID, matching some ID in a data sheet? It
would be nice to have something a little more explicit as to what the
valid values of the cell are.

Otherwise this looks fine, and seems to pair fine with the generic
bindings. The nit above can be corrected with a followup.

Acked-by: Mark Rutland <mark.rutland@....com>

Mark.

> +
> +Example:
> +
> +        tcsr: syscon@...00000 {
> +		compatible = "qcom,tcsr-msm8974", "syscon";
> +		reg = <0xfd484000 0x2000>;
> +	};
> +
> +	hwlock@...84000 {
> +		compatible = "qcom,tcsr-mutex";
> +		syscon = <&tcsr 0 0x80>;
> +
> +		#hwlock-cells = <1>;
> +	};
> -- 
> 1.8.2.2
> 
> 
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