Re: [PATCH 4/8] arm64: dts: add NXP S32G2 support

["Andreas Färber" <afaerber@suse.de>]

Hi Chester et al.,

On 05.08.21 08:54, Chester Lin wrote:
> Add an initial dtsi file for generic SoC features of NXP S32G2.
> 
> Signed-off-by: Chester Lin <clin@suse.com>
> ---
>  arch/arm64/boot/dts/freescale/s32g2.dtsi | 98 ++++++++++++++++++++++++
>  1 file changed, 98 insertions(+)
>  create mode 100644 arch/arm64/boot/dts/freescale/s32g2.dtsi
> 
> diff --git a/arch/arm64/boot/dts/freescale/s32g2.dtsi b/arch/arm64/boot/dts/freescale/s32g2.dtsi
> new file mode 100644
> index 000000000000..3321819c1a2d
> --- /dev/null
> +++ b/arch/arm64/boot/dts/freescale/s32g2.dtsi

Note: This DT is for running on the Cortex-A53 cores, but S32G2 also has
Cortex-M7 cores. For Vybrid SoCs, DTs later got contributed to also run
on its Cortex-M4 core:

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm/boot/dts/vf610.dtsi
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm/boot/dts/vf500.dtsi
vs.
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm/boot/dts/vf610m4.dtsi

Should we plan for this in our file naming here and in following patches
(e.g., s32g2-a53* vs. s32g2-m7*)? To me, a later concatenation of
s32g274am7* would look awkward, and s32g274a-m7* would sort between -evb
and -rdb2.

> @@ -0,0 +1,98 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
> +/*

 * NXP S32G2 SoC family
 *
?

@NXP: Are any models other than 274A in the queue that we should
distinguish between s32g2.dtsi and s32g274a.dtsi here already?

> + * Copyright (c) 2021 SUSE LLC
> + */
> +
> +#include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> +/ {
> +	compatible = "fsl,s32g2";
> +	interrupt-parent = <&gic>;
> +	#address-cells = <2>;
> +	#size-cells = <2>;
> +
> +	cpus {
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		cpu0: cpu@0 {
> +			device_type = "cpu";
> +			compatible = "arm,cortex-a53";
> +			reg = <0x0>;
> +			enable-method = "psci";
> +			next-level-cache = <&cluster0_l2>;
> +		};
> +
> +		cpu1: cpu@1 {
> +			device_type = "cpu";
> +			compatible = "arm,cortex-a53";
> +			reg = <0x1>;
> +			enable-method = "psci";
> +			next-level-cache = <&cluster0_l2>;
> +		};
> +
> +		cpu2: cpu@100 {
> +			device_type = "cpu";
> +			compatible = "arm,cortex-a53";
> +			reg = <0x100>;
> +			enable-method = "psci";
> +			next-level-cache = <&cluster1_l2>;
> +		};
> +
> +		cpu3: cpu@101 {
> +			device_type = "cpu";
> +			compatible = "arm,cortex-a53";
> +			reg = <0x101>;
> +			enable-method = "psci";
> +			next-level-cache = <&cluster1_l2>;
> +		};
> +
> +		cluster0_l2: l2-cache0 {
> +			compatible = "cache";
> +		};
> +
> +		cluster1_l2: l2-cache1 {
> +			compatible = "cache";
> +		};
> +	};
> +
> +	pmu {
> +		compatible = "arm,cortex-a53-pmu";
> +		interrupts = <GIC_PPI 7 IRQ_TYPE_LEVEL_HIGH>;

interrupt-affinity = <&cpu0>, <&cpu1>, <&cpu2>, <&cpu3>;

> +	};
> +
> +	timer {
> +		compatible = "arm,armv8-timer";
> +		interrupts = <GIC_PPI 13 IRQ_TYPE_LEVEL_LOW>,
> +			     <GIC_PPI 14 IRQ_TYPE_LEVEL_LOW>,
> +			     <GIC_PPI 11 IRQ_TYPE_LEVEL_LOW>,
> +			     <GIC_PPI 10 IRQ_TYPE_LEVEL_LOW>;
> +	};
> +
> +	psci {
> +		compatible = "arm,psci-1.0";
> +		method = "smc";
> +	};

Should we move this into a /firmware node, to group with future OP-TEE?

> +
> +	soc {
> +		compatible = "simple-bus";
> +		interrupt-parent = <&gic>;

Duplicate, already set on root node.

> +		#address-cells = <2>;
> +		#size-cells = <2>;

Why? Does it have any peripherals that go beyond 32-bit space?
For 64-bit Realtek platforms Rob had asked me to use 1, if possible.
I do understand that for /memory nodes we do have high-memory addresses,
so 2 for the root node looks correct.

> +

Please drop this white line.

> +		ranges;

According to Rob, the /soc ranges should exclude any RAM ranges for
safety reasons. Compare:

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm64/boot/dts/realtek/rtd129x.dtsi

If you're lacking the maximum RAM areas to carve out, NXP is in CC to
help out :) and the EVB and RDB2 boards should give you starting numbers
that could be enlarged later if needed.

> +
> +		gic: interrupt-controller@50800000 {
> +			compatible = "arm,gic-v3";
> +			#interrupt-cells = <3>;
> +			interrupt-controller;
> +			reg = <0 0x50800000 0 0x10000>,
> +			      <0 0x50880000 0 0x200000>,
> +			      <0 0x50400000 0 0x2000>,
> +			      <0 0x50410000 0 0x2000>,
> +			      <0 0x50420000 0 0x2000>;

Please order reg after compatible by convention, and sort
interrupt-controller or at least #interrupt-cells (applying to
consumers) last, after the below one applying to this device itself.

> +			interrupts = <GIC_PPI 9 (GIC_CPU_MASK_SIMPLE(4) |
> +						 IRQ_TYPE_LEVEL_HIGH)>;
> +		};

CC'ing Marc for additional GIC scrutiny, often the sizes are wrong.

> +	};
> +};

Thanks,
Andreas

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