linux-kernel - Re: [PATCH v2 1/3] coresight: bindings for debug module

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Date:   Thu, 2 Mar 2017 08:43:18 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, mike.leach@...aro.org
Subject: Re: [PATCH v2 1/3] coresight: bindings for debug module

On Wed, Mar 01, 2017 at 08:45:50AM -0700, Mathieu Poirier wrote:
> On Tue, Feb 28, 2017 at 11:06:58PM +0800, Leo Yan wrote:
> > According to ARMv8 architecture reference manual (ARM DDI 0487A.k)
> > Chapter 'Part H: External debug', the CPU can integrate debug module
> > and it can support self-hosted debug and external debug. Especially
> > for supporting self-hosted debug, this means the program can access
> > the debug module from mmio region; and usually the mmio region is
> > integrated with coresight.
> > 
> > So add document for binding debug component, includes binding to APB
> > clock; and also need specify the CPU node which the debug module is
> > dedicated to specific CPU.
> > 
> > Suggested-by: Mike Leach <mike.leach@...aro.org>
> > Signed-off-by: Leo Yan <leo.yan@...aro.org>
> > ---
> >  .../devicetree/bindings/arm/coresight-debug.txt    | 40 ++++++++++++++++++++++
> >  1 file changed, 40 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/arm/coresight-debug.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/arm/coresight-debug.txt b/Documentation/devicetree/bindings/arm/coresight-debug.txt
> > new file mode 100644
> > index 0000000..89820d5
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/arm/coresight-debug.txt
> > @@ -0,0 +1,40 @@
> > +* CoreSight Debug Component:
> > +
> > +CoreSight debug component are compliant with the ARMv8 architecture reference
> > +manual (ARM DDI 0487A.k) Chapter 'Part H: External debug'. The external debug
> > +module is mainly used for two modes: self-hosted debug and external debug, and
> > +it can be accessed from mmio region from Coresight and eventually the debug
> > +module connects with CPU for debugging. And the debug module provides
> > +sample-based profiling extension, which can be used to sample CPU program
> > +counter, secure state and exception level, etc; usually every CPU has one
> > +dedicated debug module to be connected.
> > +
> > +Required properties:
> > +
> > +- compatible : should be
> > +	     * "arm,coresight-debug", "arm,primecell"; supplemented with
> > +	       "arm,primecell" as driver is using the AMBA bus interface.
> 
>              * "arm,coresight-debug"; supplemented with "arm,primecell" since
>                this driver is using the AMBA bus interface.
> 
> > +
> > +- reg : physical base address and length of the register set.
> > +
> > +- clocks : the clock associated to this component.
> > +
> > +- clock-names : the name of the clock referenced by the code. Since we are
> > +                using the AMBA framework, the name of the clock providing
> > +		the interconnect should be "apb_pclk" and the clock is
> > +		mandatory. The interface between the debug logic and the
> > +		processor core is clocked by the internal CPU clock, so it
> > +		is enabled with CPU clock by default.
> > +
> > +- cpu : the cpu phandle the debug module is affined to. When omitted
> > +	the source is considered to belong to CPU0.
> 
> s/source/module
> 
> With those change:
> 
> Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>

Thanks for reviewing :)

> > +
> > +Example:
> > +
> > +	debug@...90000 {
> > +		compatible = "arm,coresight-debug","arm,primecell";
> > +		reg = <0 0xf6590000 0 0x1000>;
> > +		clocks = <&sys_ctrl HI6220_DAPB_CLK>;
> > +		clock-names = "apb_pclk";
> > +		cpu = <&cpu0>;
> > +	};
> > -- 
> > 2.7.4
> >