linux-kernel - Re: [PATCH v5 4/4] arm64: dts: qcom: Add CMN PLL node for IPQ9574 SoC

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Message-ID: <crcbzpxjnbceilqccbwr7uyak6z6zdwr7mhfcyaw6vvpcce6ko@zrojbtqi4st4>
Date: Mon, 28 Oct 2024 17:39:29 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Luo Jie <quic_luoj@...cinc.com>
Cc: Bjorn Andersson <andersson@...nel.org>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, quic_kkumarcs@...cinc.com, quic_suruchia@...cinc.com, 
	quic_pavir@...cinc.com, quic_linchen@...cinc.com, quic_leiwei@...cinc.com, 
	bartosz.golaszewski@...aro.org, srinivas.kandagatla@...aro.org
Subject: Re: [PATCH v5 4/4] arm64: dts: qcom: Add CMN PLL node for IPQ9574 SoC

On Mon, Oct 28, 2024 at 10:04:11PM +0800, Luo Jie wrote:
> The CMN PLL clock controller allows selection of an input clock rate
> from a defined set of input clock rates. It in-turn supplies fixed
> rate output clocks to the hardware blocks that provide the ethernet
> functions such as PPE (Packet Process Engine) and connected switch or
> PHY, and to GCC.
> 
> The reference clock of CMN PLL is routed from XO to the CMN PLL through
> the internal WiFi block.
> .XO (48 MHZ or 96 MHZ)-->WiFi (multiplier/divider)-->48 MHZ to CMN PLL.
> 
> The reference input clock from WiFi to CMN PLL is fully controlled by
> the bootstrap pins which select the XO frequency (48 MHZ or 96 MHZ).
> Based on this frequency, the divider in the internal Wi-Fi block is
> automatically configured by hardware (1 for 48 MHZ, 2 for 96 MHZ), to
> ensure output clock to CMN PLL is 48 MHZ.
> 
> Signed-off-by: Luo Jie <quic_luoj@...cinc.com>
> ---
>  arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi | 16 ++++++++++++++-
>  arch/arm64/boot/dts/qcom/ipq9574.dtsi            | 26 +++++++++++++++++++++++-
>  2 files changed, 40 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi b/arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi
> index 91e104b0f865..f026c2a9d0c0 100644
> --- a/arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi
> +++ b/arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi
> @@ -3,7 +3,7 @@
>   * IPQ9574 RDP board common device tree source
>   *
>   * Copyright (c) 2020-2021 The Linux Foundation. All rights reserved.
> - * Copyright (c) 2023, Qualcomm Innovation Center, Inc. All rights reserved.
> + * Copyright (c) 2023-2024, Qualcomm Innovation Center, Inc. All rights reserved.
>   */
>  
>  /dts-v1/;
> @@ -164,6 +164,20 @@ &usb3 {
>  	status = "okay";
>  };
>  
> +/*
> + * The bootstrap pins for the board select the XO clock frequency,
> + * which automatically enables the right dividers to ensure the
> + * reference clock output to CMNPLL is 48 MHZ.
> + */
> +&cmn_pll_ref_clk {
> +	clock-div = <1>;
> +	clock-mult = <1>;
> +};
> +
>  &xo_board_clk {
>  	clock-frequency = <24000000>;
>  };
> +
> +&xo_clk {
> +	clock-frequency = <48000000>;
> +};
> diff --git a/arch/arm64/boot/dts/qcom/ipq9574.dtsi b/arch/arm64/boot/dts/qcom/ipq9574.dtsi
> index 14c7b3a78442..ad9cdb1f76db 100644
> --- a/arch/arm64/boot/dts/qcom/ipq9574.dtsi
> +++ b/arch/arm64/boot/dts/qcom/ipq9574.dtsi
> @@ -3,10 +3,11 @@
>   * IPQ9574 SoC device tree source
>   *
>   * Copyright (c) 2020-2021 The Linux Foundation. All rights reserved.
> - * Copyright (c) 2023, Qualcomm Innovation Center, Inc. All rights reserved.
> + * Copyright (c) 2023-2024, Qualcomm Innovation Center, Inc. All rights reserved.
>   */
>  
>  #include <dt-bindings/clock/qcom,apss-ipq.h>
> +#include <dt-bindings/clock/qcom,ipq-cmn-pll.h>
>  #include <dt-bindings/clock/qcom,ipq9574-gcc.h>
>  #include <dt-bindings/interconnect/qcom,ipq9574.h>
>  #include <dt-bindings/interrupt-controller/arm-gic.h>
> @@ -19,6 +20,12 @@ / {
>  	#size-cells = <2>;
>  
>  	clocks {
> +		cmn_pll_ref_clk: cmn-pll-ref-clk {
> +			compatible = "fixed-factor-clock";
> +			clocks = <&xo_clk>;
> +			#clock-cells = <0>;
> +		};
> +
>  		sleep_clk: sleep-clk {
>  			compatible = "fixed-clock";
>  			#clock-cells = <0>;
> @@ -28,6 +35,11 @@ xo_board_clk: xo-board-clk {
>  			compatible = "fixed-clock";
>  			#clock-cells = <0>;
>  		};
> +
> +		xo_clk: xo-clk {
> +			compatible = "fixed-clock";
> +			#clock-cells = <0>;
> +		};

What is the difference between xo_clk and xo_board_clk? Are there two
different crystals?

>  	};
>  
>  	cpus {

-- 
With best wishes
Dmitry