linux-kernel - Re: [PATCH 1/2] dt-bindings: cpufreq: Introduce QCOM CPUFREQ FW bindings

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Date:   Thu, 7 Jun 2018 12:50:32 +0530
From:   Taniya Das <tdas@...eaurora.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Stephen Boyd <sboyd@...nel.org>, robh@...nel.org,
        Rajendra Nayak <rnayak@...eaurora.org>,
        devicetree@...r.kernel.org, skannan@...eaurora.org
Subject: Re: [PATCH 1/2] dt-bindings: cpufreq: Introduce QCOM CPUFREQ FW
 bindings

Hello Sudeep,

Thanks for the review comments.

On 6/4/2018 4:25 PM, Sudeep Holla wrote:
> On Mon, Jun 04, 2018 at 04:16:33PM +0530, Taniya Das wrote:
>> Add QCOM cpufreq firmware device bindings for Qualcomm Technology Inc's
>> SoCs. This is required for managing the cpu frequency transitions which are
>> controlled by firmware.
>>
>> Signed-off-by: Taniya Das <tdas@...eaurora.org>
>> ---
>>   .../bindings/cpufreq/cpufreq-qcom-fw.txt           | 173 +++++++++++++++++++++
>>   1 file changed, 173 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/cpufreq/cpufreq-qcom-fw.txt
>>
>> diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-qcom-fw.txt b/Documentation/devicetree/bindings/cpufreq/cpufreq-qcom-fw.txt
>> new file mode 100644
>> index 0000000..e3087ec
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-qcom-fw.txt
>> @@ -0,0 +1,173 @@
>> +Qualcomm Technologies, Inc. CPUFREQ Bindings
>> +
>> +CPUFREQ FW is a hardware engine used by some Qualcomm Technologies, Inc. (QTI)
>> +SoCs to manage frequency in hardware. It is capable of controlling frequency
>> +for multiple clusters.
>> +
>> +Properties:
>> +- compatible
>> +	Usage:		required
>> +	Value type:	<string>
>> +	Definition:	must be "qcom,cpufreq-fw".
>> +
>> +* Property qcom,freq-domain
>> +Devices supporting freq-domain must set their "qcom,freq-domain" property with
>> +phandle to a freq_domain_table in their DT node.
>> +
>> +* Frequency Domain Table Node
>> +
>> +This describes the frequency domain belonging to a device.
>> +This node can have following properties:
>> +
>> +- reg
>> +	Usage:		required
>> +	Value type:	<prop-encoded-array>
>> +	Definition:	Addresses and sizes for the memory of the perf
>> +			, lut and enable bases.
>> +			perf - indicates the base address for the desired
>> +			performance state to be set.
>> +			lut - indicates the look up table base address for the
>> +			cpufreq	driver to read frequencies.
>> +			enable - indicates the enable register for firmware.
>> +- reg-names
>> +	Usage:		required
>> +	Value type:	<stringlist>
>> +	Definition:	Address names. Must be "perf", "lut", "enable".
>> +			Must be specified in the same order as the reg property.
>> +
> 
> [...]
> 
>> +
>> +	qcom,cpufreq-fw {
>> +		compatible = "qcom,cpufreq-fw";
>> +
>> +		#address-cells = <1>;
>> +		#size-cells = <1>;
>> +
>> +		freq_domain_table0 : freq_table0 {
>> +			reg = <0x17d43920 0x4>, <0x17d43110 0x500>,
>> +				 <0x17d41000 0x4>;
> 
> Are "perf", "lut", "enable" registers part of single IP block / share memory ?
> I am just trying to understand the reason for separate entries in this fashion
> as part of DT register property. I am wondering if there will be multiple
> entries that fall with the page size.
> 

They are part of the same IP block and these are the only register 
offsets which is required to be accessed by HLOS.

> --
> Regards,
> Sudeep
> 

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