Re: [PATCH] arm64: dts: qcom: shikra: Add BAM-DMUX support

[Stephan Gerhold]

On Thu, Jun 11, 2026 at 02:11:59PM +0530, Vishnu Santhosh wrote:
> Add required nodes to enable the upstream BAM-DMUX WWAN driver on
> Qualcomm Shikra SoC.
> 
> The SMSM (Shared Memory State Machine) node provides the power
> control signaling between the AP and modem for BAM-DMUX. The
> BAM DMA controller node describes the A2 modem BAM hardware as a
> standard DMA controller. The BAM-DMUX node references the DMA
> channels and the pc/pc-ack interrupt lines from the modem SMSM
> entry for power control signaling.
> 
> Signed-off-by: Vishnu Santhosh <vishnu.santhosh@xxxxxxxxxxxxxxxx>

I'm quite surprised to see this 15+ years(?) old hardware block being
brought back to a new SoC. Is Shikra not using IPA?

> ---
>  arch/arm64/boot/dts/qcom/shikra.dtsi | 51 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 51 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/shikra.dtsi b/arch/arm64/boot/dts/qcom/shikra.dtsi
> index a4334d99c1f35ee851ca8266ec37d4a200a07ee5..3e59d5f6323c0d857f376316faa26c503e67f6bc 100644
> --- a/arch/arm64/boot/dts/qcom/shikra.dtsi
> +++ b/arch/arm64/boot/dts/qcom/shikra.dtsi
> @@ -17,6 +17,23 @@ / {
>  	#address-cells = <2>;
>  	#size-cells = <2>;
>  
> +	bam_dmux: bam-dmux {
> +		compatible = "qcom,bam-dmux";
> +
> +		interrupts-extended = <&modem_smsm 1 IRQ_TYPE_EDGE_BOTH>,
> +				      <&modem_smsm 11 IRQ_TYPE_EDGE_BOTH>;
> +		interrupt-names = "pc",
> +				  "pc-ack";
> +
> +		qcom,smem-states = <&apps_smsm 1>,
> +				   <&apps_smsm 11>;
> +		qcom,smem-state-names = "pc",
> +					"pc-ack";
> +
> +		dmas = <&bam_dmux_dma 4>, <&bam_dmux_dma 5>;
> +		dma-names = "tx", "rx";
> +	};

This should be a child node of the modem remoteproc. See msm8916.dtsi
for example.

> +
>  	clocks {
>  		xo_board: xo-board {
>  			compatible = "fixed-clock";
> @@ -314,6 +331,28 @@ lmcu_dtb_mem: lmcu-dtb@b4702000 {
>  		};
>  	};
>  
> +	smsm {
> +		compatible = "qcom,smsm";
> +
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		mboxes = <0>, <&apcs_glb 13>;
> +
> +		apps_smsm: apps@0 {
> +			reg = <0>;
> +			#qcom,smem-state-cells = <1>;
> +		};
> +
> +		modem_smsm: modem@1 {
> +			reg = <1>;
> +			interrupts = <GIC_SPI 69 IRQ_TYPE_EDGE_RISING 0>;
> +
> +			interrupt-controller;
> +			#interrupt-cells = <2>;
> +		};
> +	};
> +
>  	soc: soc@0 {
>  		compatible = "simple-bus";
>  
> @@ -640,6 +679,18 @@ &clk_virt SLAVE_QUP_CORE_0 RPM_ALWAYS_TAG>,
>  			};
>  		};
>  
> +		bam_dmux_dma: dma-controller@6044000 {
> +			compatible = "qcom,bam-v1.7.0";
> +			reg = <0x0 0x06044000 0x0 0x19000>;
> +			interrupts = <GIC_SPI 74 IRQ_TYPE_EDGE_RISING 0>;
> +			#dma-cells = <1>;
> +			qcom,ee = <0>;
> +
> +			num-channels = <6>;
> +			qcom,num-ees = <1>;
> +			qcom,powered-remotely;
> +		};
> +
>  		sram@c11e000 {
>  			compatible = "qcom,shikra-imem", "mmio-sram";
>  			reg = <0x0 0x0c11e000 0x0 0x1000>;
> 
> ---
> base-commit: ba3e43a9e601636f5edb54e259a74f96ca3b8fd8
> change-id: 20260603-qcom-shikra-dts-bam-dmux-7fdcbb6fb662
> prerequisite-message-id: <20260527-shikra-dt-v4-0-b5ca1fa0b392@xxxxxxxxxxxxxxxx>
> prerequisite-patch-id: 3a689e8dda5fd2755b689d94d095806b3f2e6eed
> prerequisite-patch-id: 2acc300a68ed8c5364fb5f2f7d28fc0d56ab07bf
> prerequisite-patch-id: 2357cac636e019eaf14d6a493a1c72bca56fe405
> prerequisite-patch-id: 2885f299e711582da312ca9d13983d296a3dd5dc
> prerequisite-patch-id: 91af5f3c01e766a53ce8de69aa21847a2d6bbbf8
> 

If the DT isn't merged yet, you can also just squash that into the
existing series that adds the modem remoteproc.

Thanks,
Stephan