Re: [PATCH v2 2/7] dt-bindings: soc: qcom: Add device tree binding for GENI SE

From: Rob Herring <robh@kernel.org>
To: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>,
	corbet@lwn.net, andy.gross@linaro.org, david.brown@linaro.org,
	mark.rutland@arm.com, wsa@the-dreams.de,
	gregkh@linuxfoundation.org, linux-doc@vger.kernel.org,
	linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
	linux-i2c@vger.kernel.org, linux-serial@vger.kernel.org,
	jslaby@suse.com
Subject: Re: [PATCH v2 2/7] dt-bindings: soc: qcom: Add device tree binding for GENI SE
Date: Fri, 19 Jan 2018 16:53:32 -0600	[thread overview]
Message-ID: <20180119225332.2umo6mxqs3szfy6x@rob-hp-laptop> (raw)
In-Reply-To: <20180117062558.GB6620@minitux>

On Tue, Jan 16, 2018 at 10:25:58PM -0800, Bjorn Andersson wrote:
> On Fri 12 Jan 17:05 PST 2018, Karthikeyan Ramasubramanian wrote:
> 
> > Add device tree binding support for the QCOM GENI SE driver.
> > 
> > Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
> 
> Better describe the entire GENI, with it's functions in the same
> binding.
> 
> > ---
> >  .../devicetree/bindings/soc/qcom/qcom,geni-se.txt  | 34 ++++++++++++++++++++++
> >  1 file changed, 34 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/soc/qcom/qcom,geni-se.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,geni-se.txt b/Documentation/devicetree/bindings/soc/qcom/qcom,geni-se.txt
> > new file mode 100644
> > index 0000000..66f8a16
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/soc/qcom/qcom,geni-se.txt
> > @@ -0,0 +1,34 @@
> > +Qualcomm Technologies, Inc. GENI Serial Engine QUP Wrapper Controller
> > +
> > +Generic Interface (GENI) based Qualcomm Universal Peripheral (QUP) wrapper
> > +is a programmable module for supporting a wide range of serial interfaces
> > +like UART, SPI, I2C, I3C, etc. A single QUP module can provide upto 8 Serial
> > +Interfaces, using its internal Serial Engines. The GENI Serial Engine QUP
> > +Wrapper controller is modeled as a node with zero or more child nodes each
> > +representing a serial engine.
> > +
> > +Required properties:
> > +- compatible:		Must be "qcom,geni-se-qup".
> > +- reg:			Must contain QUP register address and length.
> > +- clock-names:		Must contain "m-ahb" and "s-ahb".
> > +- clocks:		AHB clocks needed by the device.
> > +
> > +Required properties if child node exists:
> > +- #address-cells: Must be 1
> > +- #size-cells: Must be 1
> 
> But on a 64-bit system, shouldn't these be 2?

No, depends on the bus and ranges. It annoys me to no end that folks 
needlessly use 2 cells when the perpheral address space and/or module 
sizes don't exceed 4G. 

> 
> > +- ranges: Must be present

And ideally with a value, but that's beyond the scope of the binding.

> > +
> > +Properties for children:
> > +
> > +A GENI based QUP wrapper controller node can contain 0 or more child nodes
> > +representing serial devices.  These serial devices can be a QCOM UART, I2C
> > +controller, spi controller, or some combination of aforementioned devices.
> > +
> > +Example:
> > +	qup0: qcom,geniqup0@8c0000 {
> 
> I don't see a reason for this to be referenced, so skip the label. And
> don't use qcom, in the node name; "geni" would be perfectly fine?
> 
> > +		compatible = "qcom,geni-se-qup";
> > +		reg = <0x8c0000 0x6000>;
> > +		clock-names = "m-ahb", "s-ahb";
> > +		clocks = <&clock_gcc GCC_QUPV3_WRAP_0_M_AHB_CLK>,
> > +			<&clock_gcc GCC_QUPV3_WRAP_0_S_AHB_CLK>;
> > +	}
> 
> Regards,
> Bjorn