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

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Date:   Mon, 4 Jun 2018 11:55:31 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Taniya Das <tdas@...eaurora.org>
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,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH 1/2] dt-bindings: cpufreq: Introduce QCOM CPUFREQ FW
 bindings

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.

--
Regards,
Sudeep