linux-kernel - RE: [PATCH v5 1/4] dt-bindings: firmware: Add bindings for ZynqMP firmware

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Date:   Wed, 7 Mar 2018 22:25:03 +0000
From:   Jolly Shah <JOLLYS@...inx.com>
To:     Sudeep Holla <sudeep.holla@....com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "matt@...eblueprint.co.uk" <matt@...eblueprint.co.uk>,
        "hkallweit1@...il.com" <hkallweit1@...il.com>,
        "michal.simek@...inx.com" <michal.simek@...inx.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>
CC:     "ard.biesheuvel@...aro.org" <ard.biesheuvel@...aro.org>,
        "mingo@...nel.org" <mingo@...nel.org>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "dmitry.torokhov@...il.com" <dmitry.torokhov@...il.com>,
        Rajan Vaja <RAJANV@...inx.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: RE: [PATCH v5 1/4] dt-bindings: firmware: Add bindings for ZynqMP
 firmware

Hi Sudeep,

> -----Original Message-----
> From: Sudeep Holla [mailto:sudeep.holla@....com]
> Sent: Thursday, March 01, 2018 6:15 AM
> To: Jolly Shah <JOLLYS@...inx.com>; gregkh@...uxfoundation.org;
> matt@...eblueprint.co.uk; hkallweit1@...il.com; michal.simek@...inx.com;
> robh+dt@...nel.org; mark.rutland@....com
> Cc: ard.biesheuvel@...aro.org; mingo@...nel.org; keescook@...omium.org;
> dmitry.torokhov@...il.com; Sudeep Holla <sudeep.holla@....com>; Rajan
> Vaja <RAJANV@...inx.com>; linux-arm-kernel@...ts.infradead.org; linux-
> kernel@...r.kernel.org; devicetree@...r.kernel.org; Jolly Shah
> <JOLLYS@...inx.com>
> Subject: Re: [PATCH v5 1/4] dt-bindings: firmware: Add bindings for ZynqMP
> firmware
> 
> 
> 
> On 20/02/18 19:21, Jolly Shah wrote:
> > Add documentation to describe Xilinx ZynqMP firmware driver bindings.
> > Firmware driver provides an interface to firmware APIs. Interface APIs
> > can be used by any driver to communicate to PMUFW (Platform Management
> > Unit).
> >
> > Signed-off-by: Jolly Shah <jollys@...inx.com>
> > Signed-off-by: Rajan Vaja <rajanv@...inx.com>
> > ---
> >  .../firmware/xilinx/xlnx,zynqmp-firmware.txt       | 24
> ++++++++++++++++++++++
> >  1 file changed, 24 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/firmware/xilinx/xlnx,zynqmp-firmware
> > .txt
> >
> > diff --git
> > a/Documentation/devicetree/bindings/firmware/xilinx/xlnx,zynqmp-firmwa
> > re.txt
> > b/Documentation/devicetree/bindings/firmware/xilinx/xlnx,zynqmp-firmwa
> > re.txt
> > new file mode 100644
> > index 0000000..99434ba
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/firmware/xilinx/xlnx,zynqmp-fi
> > +++ rmware.txt
> > @@ -0,0 +1,24 @@
> > +Xilinx Zynq MPSoC Firmware Device Tree Bindings
> > +
> > +The zynqmp-firmware node describes the interface to platform firmware.
> > +ZynqMP has an interface to communicate with secure firmware. Firmware
> > +driver provides an interface to firmware APIs. Interface APIs can be
> > +used by any driver to communicate to PMUFW(Platform Management Unit).
> > +These requests include clock management, pin control, device control,
> > +power management service, FPGA service and other platform management
> > +services.
> > +
> > +Required properties:
> > + - compatible:	Must contain:  "xlnx,zynqmp-firmware"
> > + - method:	The method of calling the PM-API firmware layer.
> > +		Permitted values are:
> > +		  - "smc" : SMC #0, following the SMCCC
> > +		  - "hvc" : HVC #0, following the SMCCC
> > +
> > +Examples:
> > +	firmware {
> > +		zynqmp_firmware: zynqmp-firmware {
> > +			compatible = "xlnx,zynqmp-firmware";
> > +			method = "smc";
> > +		};
> > +	};
> >
> 
> Do you foresee using SMC/HVC for this firmware even on future platforms?
> If not, I suggest to keep the protocol part separate from the transport i.e.
> smc/hvc via ATF. It could be replaced with mailbox or some h/w mechanism in
> future ?
> 

We have PSCI and EEMI interfaces exposed to linux from ATF.  PSCI is an EEMI client. We do not have current plans to switch to mailbox as it will require 2 communication channels to PMU as PSCI is through ATF. 

> --
> Regards,
> Sudeep