linux-kernel - Re: [PATCH v4 3/5] dt-bindings: Add TI SCI PM Domains

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Message-ID: <4b4e71a1-53d2-cbbb-571f-61a73ada79fc@ti.com>
Date:   Wed, 15 Mar 2017 15:14:59 -0500
From:   Dave Gerlach <d-gerlach@...com>
To:     Rob Herring <robh@...nel.org>
CC:     Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, Nishanth Menon <nm@...com>,
        Keerthy <j-keerthy@...com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Tero Kristo <t-kristo@...com>,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH v4 3/5] dt-bindings: Add TI SCI PM Domains

On 03/15/2017 12:53 PM, Rob Herring wrote:
> On Tue, Mar 07, 2017 at 04:22:32AM -0600, Dave Gerlach wrote:
>> Add a generic power domain implementation, TI SCI PM Domains, that
>> will hook into the genpd framework and allow the TI SCI protocol to
>> control device power states.
>>
>> Also, provide macros representing each device index as understood
>> by TI SCI to be used in the device node power-domain references.
>> These are identifiers for the K2G devices managed by the PMMC.
>>
>> Signed-off-by: Nishanth Menon <nm@...com>
>> Signed-off-by: Dave Gerlach <d-gerlach@...com>
>> ---
>>  .../devicetree/bindings/soc/ti/sci-pm-domain.txt   | 59 ++++++++++++++
>>  MAINTAINERS                                        |  2 +
>>  include/dt-bindings/genpd/k2g.h                    | 90 ++++++++++++++++++++++
>>  3 files changed, 151 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
>>  create mode 100644 include/dt-bindings/genpd/k2g.h
>>
>> diff --git a/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt b/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
>> new file mode 100644
>> index 000000000000..86a6a3d52ed6
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
>> @@ -0,0 +1,59 @@
>> +Texas Instruments TI-SCI Generic Power Domain
>> +---------------------------------------------
>> +
>> +Some TI SoCs contain a system controller (like the PMMC, etc...) that is
>> +responsible for controlling the state of the IPs that are present.
>> +Communication between the host processor running an OS and the system
>> +controller happens through a protocol known as TI-SCI [1]. This pm domain
>> +implementation plugs into the generic pm domain framework and makes use of
>> +the TI SCI protocol power on and off each device when needed.
>
> The last sentence is mostly Linux implementation details. The binding is
> power domains. The Linux framework is PM domains. Let's keep those
> distinct and the latter doesn't belong in bindings.

Ok, I will send an update to just this patch and drop the last sentence above.

Regards,
Dave

>
>> +
>> +[1] Documentation/devicetree/bindings/arm/keystone/ti,sci.txt
>> +
>> +PM Domain Node
>> +==============
>> +The PM domain node represents the global PM domain managed by the PMMC, which
>> +in this case is the implementation as documented by the generic PM domain
>> +bindings in Documentation/devicetree/bindings/power/power_domain.txt.  Because
>> +this relies on the TI SCI protocol to communicate with the PMMC it must be a
>> +child of the pmmc node.
>> +
>> +Required Properties:
>> +--------------------
>> +- compatible: should be "ti,sci-pm-domain"
>> +- #power-domain-cells: Must be 1 so that an id can be provided in each
>> +		       device node.
>> +
>> +Example (K2G):
>> +-------------
>> +	pmmc: pmmc {
>> +		compatible = "ti,k2g-sci";
>> +		...
>> +
>> +		k2g_pds: power-controller {
>> +			compatible = "ti,sci-pm-domain";
>> +			#power-domain-cells = <1>;
>> +		};
>> +	};
>> +
>> +PM Domain Consumers
>> +===================
>> +Hardware blocks belonging to a PM domain should contain a "power-domains"
>> +property that is a phandle pointing to the corresponding PM domain node
>> +along with an index representing the device id to be passed to the PMMC
>> +for device control.
>> +
>> +Required Properties:
>> +--------------------
>> +- power-domains: phandle pointing to the corresponding PM domain node
>> +		 and an ID representing the device.
>> +
>> +See dt-bindings/genpd/k2g.h for the list of valid identifiers for k2g.
>> +
>> +Example (K2G):
>> +--------------------
>> +	uart0: serial@...30c00 {
>> +		compatible = "ns16550a";
>> +		...
>> +		power-domains = <&k2g_pds K2G_DEV_UART0>;
>> +	};