From: Oleksii Moisieiev <Oleksii_Moisieiev@epam.com>
To: Sudeep Holla <sudeep.holla@arm.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>,
"robh+dt@kernel.org" <robh+dt@kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
Cristian Marussi <cristian.marussi@arm.com>,
Stefano Stabellini <sstabellini@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 0/1] dt-bindings: arm: Add scmi_devid paramter for
Date: Tue, 22 Feb 2022 17:34:59 +0000 [thread overview]
Message-ID: <20220222173458.GA2310133@EPUAKYIW015D> (raw)
In-Reply-To: <20220222161440.xadrgjftdyxenxgo@bogus>
On Tue, Feb 22, 2022 at 04:14:40PM +0000, Sudeep Holla wrote:
> On Tue, Feb 22, 2022 at 09:06:25AM +0100, Krzysztof Kozlowski wrote:
> > On 21/02/2022 22:39, Oleksii Moisieiev wrote:
> > > Hi Krzysztof,
> > >
> > > On Mon, Feb 21, 2022 at 10:01:43PM +0100, Krzysztof Kozlowski wrote:
> > >> On 21/02/2022 18:26, Oleksii Moisieiev wrote:
> > >>> Introducing new parameter called scmi_devid to the device-tree bindings.
> > >>> This parameter should be set for the device nodes, which has
> > >>> clocks/power-domains/resets working through SCMI.
> > >>> Given parameter should set the device_id, needed to set device
> > >>> permissions in the Firmware. This feature will be extremely useful for
> > >>> the virtualized systems, which has more that one Guests running on the
> > >>> system at the same time or for the syestems, which require several
> > >>> agents with different permissions. Trusted agent will use scmi_devid to
> > >>> set the Device permissions for the Firmware (See Section 4.2.2.10 [0]
> > >>> for details).
> > >>> Agents concept is described in Section 4.2.1 [0].
> > >>>
> > >>> scmi_devid in Device-tree node example:
> > >>> usb@e6590000
> > >>> {
> > >>> scmi_devid = <19>;
> > >>> clocks = <&scmi_clock 3>, <&scmi_clock 2>;
> > >>> resets = <&scmi_reset 10>, <&scmi_reset 9>;
> > >>> power-domains = <&scmi_power 0>;
> > >>> };
> > >>
> > >> And how do you prevent DT overlay adding such devid to any other node
> > >> thus allowing any other device to send requests with given devid?
> > >>
> > > Thank you for the quick response.
> > > scmi_devid value will be used only by Trusted Agent when the device
> > > permissions are set. Non-trusted agents, which in our case are
> > > represented as Guest OS are using scmi drivers, already present in linux
> > > kernel, ignores scmi_devid and uses scmi_clocks, scmi_power, scmi_reset
> > > nodes to access to SCMI protocol.
> >
> > Ah, ok.
> >
> > >
> > >> Plus few technicalities:
> > >> 1. Hyphen, not underscore in property name, so scmi-devid.
> > >
> > > Thanks for the tip, I will change that in v2.
> >
> > Few more thoughts:
> > 1. This looks specific to ARM SCMI, so you also need vendor prefix, so
> > something like:
> > arm,scmi-devid
> > arm,scmi-device-id
> >
>
> Keeping the other discussion separate, I wanted to comment on this.
> I agree with Krzysztof on having vendor specific prefix if we decide to add
> this device id thing. However, I prefer not to use "arm,scmi-" here.
> It can be "xen,scmi-" as we had plans to introduce some concepts in SCMI
> spec that may use looks like this device-id. I would just like to avoid
> conflicting with that in the future. It may happen to be same in the future
> (i.e. this xen device-id matches 100% with definition of device-id we might
> introduce in the spec, but I want to make assumption otherwise and leave
> scope for divergence however small/little it can be). No issues even if
> they converge and match 100% later in the far future.
>
xem,scmi- works for me. What do other thinks?
next prev parent reply other threads:[~2022-02-22 17:35 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-21 17:26 [RFC PATCH 0/1] dt-bindings: arm: Add scmi_devid paramter for Oleksii Moisieiev
2022-02-21 17:26 ` [RFC PATCH 1/1] dt-bindings: arm: Add scmi_devid property description for SCMI Oleksii Moisieiev
2022-02-22 14:22 ` Rob Herring
2022-02-22 14:51 ` Oleksii Moisieiev
2022-02-22 18:25 ` Rob Herring
2022-02-21 21:01 ` [RFC PATCH 0/1] dt-bindings: arm: Add scmi_devid paramter for Krzysztof Kozlowski
2022-02-21 21:39 ` Oleksii Moisieiev
2022-02-22 8:06 ` Krzysztof Kozlowski
2022-02-22 8:55 ` Oleksii Moisieiev
2022-02-22 9:27 ` Krzysztof Kozlowski
2022-02-22 10:30 ` Oleksii Moisieiev
2022-02-22 11:16 ` Krzysztof Kozlowski
2022-02-22 13:54 ` Oleksii Moisieiev
2022-02-22 16:14 ` Sudeep Holla
2022-02-22 17:34 ` Oleksii Moisieiev [this message]
2022-02-24 2:51 ` Stefano Stabellini
2022-02-24 9:32 ` Cristian Marussi
2022-02-24 22:22 ` Stefano Stabellini
2022-03-01 14:55 ` Oleksii Moisieiev
2022-03-04 11:21 ` Sudeep Holla
2022-03-04 11:18 ` Sudeep Holla
2022-02-22 11:00 ` Cristian Marussi
2022-02-22 13:51 ` Oleksii Moisieiev
2022-02-22 16:06 ` Sudeep Holla
2022-02-22 17:15 ` Oleksii Moisieiev
2022-02-24 11:54 ` Sudeep Holla
2022-02-24 22:51 ` Stefano Stabellini
2022-02-24 23:34 ` Stefano Stabellini
2022-03-04 11:12 ` Sudeep Holla
2022-03-05 0:45 ` Stefano Stabellini
2022-04-29 21:46 ` Rob Herring
2022-03-01 16:10 ` Oleksii Moisieiev
2022-03-01 16:05 ` Oleksii Moisieiev
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