[PATCH 0/2] Add Arm Zena CSS support

[PATCH 0/2] Add Arm Zena CSS support

[Debbie Horsfall]

This series adds the Arm Zena Compute Subsystem schemas and
Devicetree. Currently, the only platform variant is the Fixed
Virtual Platform. More information on Arm Zena CSS can be found
at https://www.arm.com/products/automotive/compute-subsystems/zena

Signed-off-by: Debbie Horsfall <debbie.horsfall@arm.com>
---
Debbie Horsfall (2):
      dt-bindings: arm: Add Zena CSS compatibility
      arm64: dts: zena: Add support for Zena CSS

 .../devicetree/bindings/arm/arm,zena-css.yaml      |  31 +
 MAINTAINERS                                        |   6 +
 arch/arm64/boot/dts/arm/Makefile                   |   1 +
 arch/arm64/boot/dts/arm/zena-css-fvp.dts           |  55 ++
 arch/arm64/boot/dts/arm/zena-css.dtsi              | 826 +++++++++++++++++++++
 5 files changed, 919 insertions(+)
---
base-commit: c072629f05d7bca1148ab17690d7922a31423984
change-id: 20260123-zena-css-7b52f0f2a967

Best regards,
-- 
Debbie Horsfall <debbie.horsfall@arm.com>

[PATCH 1/2] dt-bindings: arm: Add Zena CSS compatibility

[Debbie Horsfall]

Add compatibility to Arm Zena CSS Fixed Virtual Platform [1].

[1] https://www.arm.com/products/automotive/compute-subsystems/zena

Signed-off-by: Debbie Horsfall <debbie.horsfall@arm.com>
---
 .../devicetree/bindings/arm/arm,zena-css.yaml      | 31 ++++++++++++++++++++++
 MAINTAINERS                                        |  5 ++++
 2 files changed, 36 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/arm,zena-css.yaml b/Documentation/devicetree/bindings/arm/arm,zena-css.yaml
new file mode 100644
index 000000000000..42699b4db41e
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/arm,zena-css.yaml
@@ -0,0 +1,31 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/arm,zena-css.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Arm Zena Compute Subsystem Platforms
+
+maintainers:
+  - Debbie Horsfall <debbie.horsfall@arm.com>
+
+description:
+  Arm Zena Compute Subsystem (CSS) is a compute platform targeting
+  the automotive sector. Arm Zena CSS is a high-performance Arm
+  Cortex-A720AE Application Processor system augmented with an Arm
+  Cortex-R82AE based Safety Island and real-time domain.
+
+properties:
+  $nodename:
+    const: '/'
+  compatible:
+    oneOf:
+      - description: Arm Zena CSS Platforms
+        items:
+          - enum:
+              - arm,zena-css-fvp
+          - const: arm,zena-css
+
+additionalProperties: true
+
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 6863d5fa07a1..90d88137adf1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3723,6 +3723,11 @@ F:	drivers/video/fbdev/vt8500lcdfb.*
 F:	drivers/video/fbdev/wm8505fb*
 F:	drivers/video/fbdev/wmt_ge_rops.*
 
+ARM/ZENA CSS PLATFORM
+M:	Debbie Horsfall <debbie.horsfall@arm.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/arm/arm,zena-css.yaml
+
 ARM/ZYNQ ARCHITECTURE
 M:	Michal Simek <michal.simek@amd.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)

-- 
2.43.0

Re: [PATCH 1/2] dt-bindings: arm: Add Zena CSS compatibility

[Rob Herring (Arm)]

On Fri, 23 Jan 2026 17:37:46 +0000, Debbie Horsfall wrote:
> Add compatibility to Arm Zena CSS Fixed Virtual Platform [1].
> 
> [1] https://www.arm.com/products/automotive/compute-subsystems/zena
> 
> Signed-off-by: Debbie Horsfall <debbie.horsfall@arm.com>
> ---
>  .../devicetree/bindings/arm/arm,zena-css.yaml      | 31 ++++++++++++++++++++++
>  MAINTAINERS                                        |  5 ++++
>  2 files changed, 36 insertions(+)
> 

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>

Re: [PATCH 1/2] dt-bindings: arm: Add Zena CSS compatibility

[Krzysztof Kozlowski]

On 23/01/2026 18:37, Debbie Horsfall wrote:
> Add compatibility to Arm Zena CSS Fixed Virtual Platform [1].
> 
> [1] https://www.arm.com/products/automotive/compute-subsystems/zena
> 
> Signed-off-by: Debbie Horsfall <debbie.horsfall@arm.com>
> ---
>  .../devicetree/bindings/arm/arm,zena-css.yaml      | 31 ++++++++++++++++++++++
>  MAINTAINERS                                        |  5 ++++
>  2 files changed, 36 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/arm/arm,zena-css.yaml b/Documentation/devicetree/bindings/arm/arm,zena-css.yaml
> new file mode 100644
> index 000000000000..42699b4db41e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/arm,zena-css.yaml

This should really go to one YAML file for most of FVP from ARM.

Best regards,
Krzysztof

Re: [PATCH 1/2] dt-bindings: arm: Add Zena CSS compatibility

[Sudeep Holla]

On Thu, Feb 05, 2026 at 01:29:18PM +0100, Krzysztof Kozlowski wrote:
> On 23/01/2026 18:37, Debbie Horsfall wrote:
> > Add compatibility to Arm Zena CSS Fixed Virtual Platform [1].
> > 
> > [1] https://www.arm.com/products/automotive/compute-subsystems/zena
> > 
> > Signed-off-by: Debbie Horsfall <debbie.horsfall@arm.com>
> > ---
> >  .../devicetree/bindings/arm/arm,zena-css.yaml      | 31 ++++++++++++++++++++++
> >  MAINTAINERS                                        |  5 ++++
> >  2 files changed, 36 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/arm/arm,zena-css.yaml b/Documentation/devicetree/bindings/arm/arm,zena-css.yaml
> > new file mode 100644
> > index 000000000000..42699b4db41e
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/arm/arm,zena-css.yaml
> 
> This should really go to one YAML file for most of FVP from ARM.
> 

Fair point, we have existing FVPs in [1]. We can move this there as well
but if it becomes too much or if we can get it more organised based on
some category in the future, we can take it up then. For now, I am happy
to shove it in [1].

-- 
Regards,
Sudeep

[1] Documentation/devicetree/bindings/arm/arm,vexpress-juno.yaml

[PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Debbie Horsfall]

Introduce the Zena CSS Fixed Virtual Platform (FVP) dts. This is
currently the only Zena CSS variant, however the common definitions are
included in a common dtsi for extensibility.

Signed-off-by: Debbie Horsfall <debbie.horsfall@arm.com>
---
 MAINTAINERS                              |   1 +
 arch/arm64/boot/dts/arm/Makefile         |   1 +
 arch/arm64/boot/dts/arm/zena-css-fvp.dts |  55 ++
 arch/arm64/boot/dts/arm/zena-css.dtsi    | 826 +++++++++++++++++++++++++++++++
 4 files changed, 883 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 90d88137adf1..d1d2dae6a71e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3727,6 +3727,7 @@ ARM/ZENA CSS PLATFORM
 M:	Debbie Horsfall <debbie.horsfall@arm.com>
 S:	Maintained
 F:	Documentation/devicetree/bindings/arm/arm,zena-css.yaml
+F:	arch/arm64/boot/dts/arm/zena-css*
 
 ARM/ZYNQ ARCHITECTURE
 M:	Michal Simek <michal.simek@amd.com>
diff --git a/arch/arm64/boot/dts/arm/Makefile b/arch/arm64/boot/dts/arm/Makefile
index f30ee045dc95..770fb145b4a9 100644
--- a/arch/arm64/boot/dts/arm/Makefile
+++ b/arch/arm64/boot/dts/arm/Makefile
@@ -8,3 +8,4 @@ dtb-$(CONFIG_ARCH_VEXPRESS) += vexpress-v2f-1xv7-ca53x2.dtb
 dtb-$(CONFIG_ARCH_VEXPRESS) += fvp-base-revc.dtb
 dtb-$(CONFIG_ARCH_VEXPRESS) += corstone1000-fvp.dtb corstone1000-mps3.dtb
 dtb-$(CONFIG_ARCH_VEXPRESS) += morello-sdp.dtb morello-fvp.dtb
+dtb-$(CONFIG_ARCH_VEXPRESS) += zena-css-fvp.dtb
diff --git a/arch/arm64/boot/dts/arm/zena-css-fvp.dts b/arch/arm64/boot/dts/arm/zena-css-fvp.dts
new file mode 100644
index 000000000000..d3c649e894d1
--- /dev/null
+++ b/arch/arm64/boot/dts/arm/zena-css-fvp.dts
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+/*
+ * Copyright (c) 2025, Arm Limited. All rights reserved.
+ */
+
+/dts-v1/;
+
+#include "zena-css.dtsi"
+
+/ {
+	model = "Zena CSS Fixed Virtual Platform";
+	compatible = "arm,zena-css-fvp", "arm,zena-css";
+
+	chosen {
+		stdout-path = &soc_serial0;
+	};
+};
+
+&soc {
+	virtio@30060000 {
+		compatible = "virtio,mmio";
+		reg = <0x0 0x30060000 0x0 0x10000>;
+		interrupts = <GIC_SPI 261 IRQ_TYPE_LEVEL_HIGH>;
+	};
+
+	virtio@30020000 {
+		compatible = "virtio,mmio";
+		reg = <0x0 0x30020000 0x0 0x10000>;
+		interrupts = <GIC_SPI 257 IRQ_TYPE_LEVEL_HIGH>;
+	};
+
+	virtio@30030000 {
+		compatible = "virtio,mmio";
+		reg = <0x0 0x30030000 0x0 0x10000>;
+		interrupts = <GIC_SPI 258 IRQ_TYPE_LEVEL_HIGH>;
+	};
+
+	virtio@30040000 {
+		compatible = "virtio,mmio";
+		reg = <0x0 0x30040000 0x0 0x10000>;
+		interrupts = <GIC_SPI 259 IRQ_TYPE_LEVEL_HIGH>;
+	};
+
+	virtio@30050000 {
+		compatible = "virtio,mmio";
+		reg = <0x0 0x30050000 0x0 0x10000>;
+		interrupts = <GIC_SPI 260 IRQ_TYPE_LEVEL_HIGH>;
+	};
+
+	virtio@30080000 {
+		compatible = "virtio,mmio";
+		reg = <0x0 0x30080000 0x0 0x10000>;
+		interrupts = <GIC_SPI 263 IRQ_TYPE_LEVEL_HIGH>;
+	};
+};
diff --git a/arch/arm64/boot/dts/arm/zena-css.dtsi b/arch/arm64/boot/dts/arm/zena-css.dtsi
new file mode 100644
index 000000000000..7825e93df0a6
--- /dev/null
+++ b/arch/arm64/boot/dts/arm/zena-css.dtsi
@@ -0,0 +1,826 @@
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+/*
+ * Copyright (c) 2025, Arm Limited. All rights reserved.
+ */
+
+#include <dt-bindings/interrupt-controller/arm-gic.h>
+
+/ {
+	interrupt-parent = <&gic>;
+	#address-cells = <2>;
+	#size-cells = <2>;
+
+	cpus {
+		#address-cells = <2>;
+		#size-cells = <0>;
+
+		/*
+		 * The latency and residency numbers below are for illustrative
+		 * purpose only and may vary on actual silicon. These values are
+		 * considered just to demonstrate that the cpuidle governor
+		 * logic works.
+		 */
+		idle-states {
+			entry-method = "psci";
+
+			CPU_SLEEP: cpu-sleep {
+				compatible = "arm,idle-state";
+				arm,psci-suspend-param = <0x0010000>;
+				local-timer-stop;
+				entry-latency-us = <800>;
+				exit-latency-us = <3200>;
+				min-residency-us = <4200>;
+			};
+			CLUSTER_SLEEP: cluster-sleep {
+				compatible = "arm,idle-state";
+				arm,psci-suspend-param = <0x1010000>;
+				local-timer-stop;
+				entry-latency-us = <1000>;
+				exit-latency-us = <3200>;
+				min-residency-us = <4500>;
+			};
+		};
+
+		cpu-map {
+
+			cluster0 {
+
+				core0 {
+					cpu = <&CPU0>;
+				};
+
+				core1 {
+					cpu = <&CPU1>;
+				};
+
+				core2 {
+					cpu = <&CPU2>;
+				};
+
+				core3 {
+					cpu = <&CPU3>;
+				};
+			};
+
+			cluster1 {
+
+				core0 {
+					cpu = <&CPU4>;
+				};
+
+				core1 {
+					cpu = <&CPU5>;
+				};
+
+				core2 {
+					cpu = <&CPU6>;
+				};
+
+				core3 {
+					cpu = <&CPU7>;
+				};
+			};
+
+			cluster2 {
+
+				core0 {
+					cpu = <&CPU8>;
+				};
+
+				core1 {
+					cpu = <&CPU9>;
+				};
+
+				core2 {
+					cpu = <&CPU10>;
+				};
+
+				core3 {
+					cpu = <&CPU11>;
+				};
+			};
+
+			cluster3 {
+
+				core0 {
+					cpu = <&CPU12>;
+				};
+
+				core1 {
+					cpu = <&CPU13>;
+				};
+
+				core2 {
+					cpu = <&CPU14>;
+				};
+
+				core3 {
+					cpu = <&CPU15>;
+				};
+			};
+		};
+
+		CPU0: cpu@0 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x00>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL0_L2_0>;
+
+			CL0_L2_0: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL0_L3>;
+			};
+		};
+
+		CPU1: cpu@100 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x100>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL0_L2_1>;
+
+			CL0_L2_1: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL0_L3>;
+			};
+		};
+
+		CPU2: cpu@200 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x200>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL0_L2_2>;
+
+			CL0_L2_2: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL0_L3>;
+			};
+		};
+
+		CPU3: cpu@300 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x300>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL0_L2_3>;
+
+			CL0_L2_3: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL0_L3>;
+			};
+		};
+
+		CPU4: cpu@10000 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x10000>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL1_L2_0>;
+
+			CL1_L2_0: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL1_L3>;
+			};
+		};
+
+		CPU5: cpu@10100 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x10100>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL1_L2_1>;
+
+			CL1_L2_1: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL1_L3>;
+			};
+		};
+
+		CPU6: cpu@10200 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x10200>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL1_L2_2>;
+
+			CL1_L2_2: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL1_L3>;
+			};
+		};
+
+		CPU7: cpu@10300 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x10300>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL1_L2_3>;
+
+			CL1_L2_3: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL1_L3>;
+			};
+		};
+
+		CPU8: cpu@20000 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x20000>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL2_L2_0>;
+
+			CL2_L2_0: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL2_L3>;
+			};
+		};
+
+		CPU9: cpu@20100 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x20100>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL2_L2_1>;
+
+			CL2_L2_1: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL2_L3>;
+			};
+		};
+
+		CPU10: cpu@20200 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x20200>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL2_L2_2>;
+
+			CL2_L2_2: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL2_L3>;
+			};
+		};
+
+		CPU11: cpu@20300 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x20300>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL2_L2_3>;
+
+			CL2_L2_3: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL2_L3>;
+			};
+		};
+
+		CPU12: cpu@30000 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x30000>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL3_L2_0>;
+
+			CL3_L2_0: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL3_L3>;
+			};
+		};
+
+		CPU13: cpu@30100 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x30100>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL3_L2_1>;
+
+			CL3_L2_1: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL3_L3>;
+			};
+		};
+
+		CPU14: cpu@30200 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x30200>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL3_L2_2>;
+
+			CL3_L2_2: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL3_L3>;
+			};
+		};
+
+		CPU15: cpu@30300 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a720ae";
+			reg = <0x00 0x30300>;
+			enable-method = "psci";
+			i-cache-size = <0x10000>;
+			i-cache-line-size = <0x40>;
+			i-cache-sets = <0x100>;
+			d-cache-size = <0x10000>;
+			d-cache-line-size = <0x40>;
+			d-cache-sets = <0x100>;
+			clocks = <&scmi_dvfs 0x00>;
+			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
+			next-level-cache = <&CL3_L2_3>;
+
+			CL3_L2_3: l2-cache {
+				compatible = "cache";
+				cache-unified;
+				cache-level = <0x02>;
+				/* 512KB */
+				cache-size = <0x80000>;
+				/* 64B */
+				cache-line-size = <0x40>;
+				/* 8-way set */
+				cache-sets = <0x400>;
+				next-level-cache = <&CL3_L3>;
+			};
+		};
+
+		CL0_L3: l3-cache0 {
+			compatible = "cache";
+			cache-unified;
+			cache-level = <0x03>;
+			/* 4MB */
+			cache-size = <0x400000>;
+			/* 64B */
+			cache-line-size = <0x40>;
+			/* 16-way set */
+			cache-sets = <0x1000>;
+		};
+
+		CL1_L3: l3-cache1 {
+			compatible = "cache";
+			cache-unified;
+			cache-level = <0x03>;
+			/* 4MB */
+			cache-size = <0x400000>;
+			/* 64B */
+			cache-line-size = <0x40>;
+			/* 16-way set */
+			cache-sets = <0x1000>;
+		};
+
+		CL2_L3: l3-cache2 {
+			compatible = "cache";
+			cache-unified;
+			cache-level = <0x03>;
+			/* 4MB */
+			cache-size = <0x400000>;
+			/* 64B */
+			cache-line-size = <0x40>;
+			/* 16-way set */
+			cache-sets = <0x1000>;
+		};
+
+		CL3_L3: l3-cache3 {
+			compatible = "cache";
+			cache-unified;
+			cache-level = <0x03>;
+			/* 4MB */
+			cache-size = <0x400000>;
+			/* 64B */
+			cache-line-size = <0x40>;
+			/* 16-way set */
+			cache-sets = <0x1000>;
+		};
+	};
+
+	dsu-pmu-0 {
+		compatible = "arm,dsu-pmu";
+		cpus = <&CPU0 &CPU1 &CPU2 &CPU3>;
+		interrupts = <GIC_SPI 216 IRQ_TYPE_EDGE_RISING>;
+	};
+
+	dsu-pmu-1 {
+		compatible = "arm,dsu-pmu";
+		cpus = <&CPU4 &CPU5 &CPU6 &CPU7>;
+		interrupts = <GIC_SPI 217 IRQ_TYPE_EDGE_RISING>;
+	};
+
+	dsu-pmu-2 {
+		compatible = "arm,dsu-pmu";
+		cpus = <&CPU8 &CPU9 &CPU10 &CPU11>;
+		interrupts = <GIC_SPI 218 IRQ_TYPE_EDGE_RISING>;
+	};
+
+	dsu-pmu-3 {
+		compatible = "arm,dsu-pmu";
+		cpus = <&CPU12 &CPU13 &CPU14 &CPU15>;
+		interrupts = <GIC_SPI 219 IRQ_TYPE_EDGE_RISING>;
+	};
+
+	memory@80000000 {
+		device_type = "memory";
+
+		/* Bank 0: start = 0x0000_0000_8000_0000, size = ~2 GiB (0x7F00_0000) */
+		reg = <
+			0x00000000  0x80000000  0x00000000  0x7F000000
+			0x00000200  0x00000000  0x00000000  0x80000000
+		>;
+	};
+
+	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>,
+			<GIC_PPI 12 IRQ_TYPE_LEVEL_LOW>;
+	};
+
+	soc_clk24mhz: clock-24000000 {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <24000000>;
+		clock-output-names = "refclk24mhz";
+	};
+
+	soc: soc {
+		compatible = "simple-bus";
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		timer@1a810000 {
+			compatible = "arm,armv7-timer-mem";
+			reg = <0x0 0x1a810000 0 0x10000>;
+			#address-cells = <1>;
+			#size-cells = <1>;
+			/* Map child space [0x0..0x30000) to parent @ 0x1a810000 */
+			ranges = <0x0 0x0 0x1a810000 0x00030000>;
+
+			frame@20000 {
+				frame-number = <0>;
+				interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
+				reg = <0x20000 0x10000>;
+			};
+		};
+
+		gic: interrupt-controller@20800000 {
+			compatible = "arm,gic-v3";
+			#redistributor-regions = <16>;
+			reg = <0x0 0x20800000 0x0 0x10000>,    /* GICD */
+				<0x0 0x20880000 0x0 0x40000>,    /* 16 * GICR */
+				<0x0 0x208c0000 0x0 0x40000>,
+				<0x0 0x20900000 0x0 0x40000>,
+				<0x0 0x20940000 0x0 0x40000>,
+				<0x0 0x20980000 0x0 0x40000>,
+				<0x0 0x209c0000 0x0 0x40000>,
+				<0x0 0x20a00000 0x0 0x40000>,
+				<0x0 0x20a40000 0x0 0x40000>,
+				<0x0 0x20a80000 0x0 0x40000>,
+				<0x0 0x20ac0000 0x0 0x40000>,
+				<0x0 0x20b00000 0x0 0x40000>,
+				<0x0 0x20b40000 0x0 0x40000>,
+				<0x0 0x20b80000 0x0 0x40000>,
+				<0x0 0x20bc0000 0x0 0x40000>,
+				<0x0 0x20c00000 0x0 0x40000>,
+				<0x0 0x20c40000 0x0 0x40000>;
+			#interrupt-cells = <3>;
+			#address-cells = <2>;
+			#size-cells = <2>;
+			ranges;
+			interrupt-controller;
+			interrupts = <GIC_PPI 9 IRQ_TYPE_LEVEL_HIGH>;
+
+			its1: msi-controller@20840000 {
+				compatible = "arm,gic-v3-its";
+				reg = <0x0 0x20840000 0x0 0x40000>;
+				msi-controller;
+				#msi-cells = <1>;
+			};
+		};
+
+		/* UART is fixed as 24MHz, both UARTCLK and PCLK */
+		soc_serial0: serial@1a400000 {
+			compatible = "arm,pl011", "arm,primecell";
+			reg = <0x0 0x1a400000 0x0 0x10000>;
+			interrupts = <GIC_SPI 52 IRQ_TYPE_LEVEL_HIGH>;
+			clocks = <&soc_clk24mhz>, <&soc_clk24mhz>;
+			clock-names = "uartclk", "apb_pclk";
+		};
+
+		watchdog@1a420000 {
+			compatible = "arm,sbsa-gwdt";
+			reg = <0x0 0x1a420000 0x0 0x10000>,
+			      <0x0 0x1a430000 0x0 0x10000>;
+			interrupts = <GIC_SPI 50 IRQ_TYPE_LEVEL_HIGH>;
+		};
+
+		rtc@300d0000 {
+			compatible = "arm,pl031", "arm,primecell";
+			reg = <0x0 0x300d0000 0x0 0x10000>;
+			interrupts = <GIC_SPI 268 IRQ_TYPE_LEVEL_HIGH>;
+			clocks = <&soc_clk24mhz>;
+			clock-names = "apb_pclk";
+		};
+
+	};
+
+	psci {
+		compatible = "arm,psci-1.0", "arm,psci-0.2", "arm,psci";
+		method = "smc";
+		cpu_suspend = <0xc4000001>;
+		cpu_off = <0x84000002>;
+		cpu_on = <0xc4000003>;
+	};
+
+	sram: sram@104000 {
+		compatible = "mmio-sram";
+		reg = <0x0 0x104000 0x0 0x00001000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0 0x0 0x104000 0x00001000>;
+
+		scmi_shmem_tx: scpshmem-sram-section@0 {
+			compatible = "arm,scmi-shmem";
+			reg = <0x0 0x100>;
+		};
+		scmi_shmem_rx: scpshmem-sram-section@100 {
+			compatible = "arm,scmi-shmem";
+			reg = <0x100 0x100>;
+		};
+	};
+
+	mbox_db_tx: mailbox@40020000 {
+		compatible = "arm,mhuv3";
+		reg = <0x0 0x40020000 0x0 0x30000>;
+		clocks = <&soc_clk24mhz>;
+		#mbox-cells = <3>;
+		interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>;
+		interrupt-names = "combined";
+	};
+
+	mbox_db_rx: mailbox@40060000 {
+		compatible = "arm,mhuv3";
+		reg = <0x0 0x40060000 0x0 0x30000>;
+		clocks = <&soc_clk24mhz>;
+		#mbox-cells = <3>;
+		interrupts = <GIC_SPI 113 IRQ_TYPE_LEVEL_HIGH>;
+		interrupt-names = "combined";
+	};
+
+	firmware {
+		scmi {
+			compatible = "arm,scmi";
+			mbox-names = "tx", "rx";
+			mboxes = <&mbox_db_tx 0 0 0 &mbox_db_rx 0 0 0 &mbox_db_rx 0 0 2>;
+			shmem = <&scmi_shmem_tx &scmi_shmem_rx>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			scmi_dvfs: protocol@13 {
+				reg = <0x13>;
+				#clock-cells = <1>;
+			};
+		};
+	};
+};

-- 
2.43.0

Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Andre Przywara]

On Fri, 23 Jan 2026 17:37:47 +0000
Debbie Horsfall <debbie.horsfall@arm.com> wrote:

Hi Debbie,

thanks for taking the time to send this upstream!

> Introduce the Zena CSS Fixed Virtual Platform (FVP) dts. This is
> currently the only Zena CSS variant, however the common definitions are
> included in a common dtsi for extensibility.
> 
> Signed-off-by: Debbie Horsfall <debbie.horsfall@arm.com>
> ---
>  MAINTAINERS                              |   1 +
>  arch/arm64/boot/dts/arm/Makefile         |   1 +
>  arch/arm64/boot/dts/arm/zena-css-fvp.dts |  55 ++
>  arch/arm64/boot/dts/arm/zena-css.dtsi    | 826 +++++++++++++++++++++++++++++++
>  4 files changed, 883 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 90d88137adf1..d1d2dae6a71e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3727,6 +3727,7 @@ ARM/ZENA CSS PLATFORM
>  M:	Debbie Horsfall <debbie.horsfall@arm.com>
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/arm/arm,zena-css.yaml
> +F:	arch/arm64/boot/dts/arm/zena-css*
>  
>  ARM/ZYNQ ARCHITECTURE
>  M:	Michal Simek <michal.simek@amd.com>
> diff --git a/arch/arm64/boot/dts/arm/Makefile b/arch/arm64/boot/dts/arm/Makefile
> index f30ee045dc95..770fb145b4a9 100644
> --- a/arch/arm64/boot/dts/arm/Makefile
> +++ b/arch/arm64/boot/dts/arm/Makefile
> @@ -8,3 +8,4 @@ dtb-$(CONFIG_ARCH_VEXPRESS) += vexpress-v2f-1xv7-ca53x2.dtb
>  dtb-$(CONFIG_ARCH_VEXPRESS) += fvp-base-revc.dtb
>  dtb-$(CONFIG_ARCH_VEXPRESS) += corstone1000-fvp.dtb corstone1000-mps3.dtb
>  dtb-$(CONFIG_ARCH_VEXPRESS) += morello-sdp.dtb morello-fvp.dtb
> +dtb-$(CONFIG_ARCH_VEXPRESS) += zena-css-fvp.dtb
> diff --git a/arch/arm64/boot/dts/arm/zena-css-fvp.dts b/arch/arm64/boot/dts/arm/zena-css-fvp.dts
> new file mode 100644
> index 000000000000..d3c649e894d1
> --- /dev/null
> +++ b/arch/arm64/boot/dts/arm/zena-css-fvp.dts
> @@ -0,0 +1,55 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> +/*
> + * Copyright (c) 2025, Arm Limited. All rights reserved.
> + */
> +
> +/dts-v1/;
> +
> +#include "zena-css.dtsi"
> +
> +/ {
> +	model = "Zena CSS Fixed Virtual Platform";
> +	compatible = "arm,zena-css-fvp", "arm,zena-css";
> +
> +	chosen {
> +		stdout-path = &soc_serial0;
> +	};
> +};
> +
> +&soc {
> +	virtio@30060000 {
> +		compatible = "virtio,mmio";
> +		reg = <0x0 0x30060000 0x0 0x10000>;
> +		interrupts = <GIC_SPI 261 IRQ_TYPE_LEVEL_HIGH>;
> +	};
> +
> +	virtio@30020000 {

I think the nodes should be ordered by their address. Do you make any
assumptions about naming of devices (/dev/vda, /dev/vdb) in your setup?

> +		compatible = "virtio,mmio";
> +		reg = <0x0 0x30020000 0x0 0x10000>;
> +		interrupts = <GIC_SPI 257 IRQ_TYPE_LEVEL_HIGH>;
> +	};
> +
> +	virtio@30030000 {
> +		compatible = "virtio,mmio";
> +		reg = <0x0 0x30030000 0x0 0x10000>;
> +		interrupts = <GIC_SPI 258 IRQ_TYPE_LEVEL_HIGH>;
> +	};
> +
> +	virtio@30040000 {
> +		compatible = "virtio,mmio";
> +		reg = <0x0 0x30040000 0x0 0x10000>;
> +		interrupts = <GIC_SPI 259 IRQ_TYPE_LEVEL_HIGH>;
> +	};
> +
> +	virtio@30050000 {
> +		compatible = "virtio,mmio";
> +		reg = <0x0 0x30050000 0x0 0x10000>;
> +		interrupts = <GIC_SPI 260 IRQ_TYPE_LEVEL_HIGH>;
> +	};
> +

Do you know if there is something at 0x30070000? Maybe something that
needs explicit enablement on the model command line? In this case we might
want a comment here.

> +	virtio@30080000 {
> +		compatible = "virtio,mmio";
> +		reg = <0x0 0x30080000 0x0 0x10000>;
> +		interrupts = <GIC_SPI 263 IRQ_TYPE_LEVEL_HIGH>;
> +	};
> +};
> diff --git a/arch/arm64/boot/dts/arm/zena-css.dtsi b/arch/arm64/boot/dts/arm/zena-css.dtsi
> new file mode 100644
> index 000000000000..7825e93df0a6
> --- /dev/null
> +++ b/arch/arm64/boot/dts/arm/zena-css.dtsi
> @@ -0,0 +1,826 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> +/*
> + * Copyright (c) 2025, Arm Limited. All rights reserved.
> + */
> +
> +#include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> +/ {
> +	interrupt-parent = <&gic>;
> +	#address-cells = <2>;
> +	#size-cells = <2>;
> +
> +	cpus {
> +		#address-cells = <2>;
> +		#size-cells = <0>;
> +
> +		/*
> +		 * The latency and residency numbers below are for illustrative
> +		 * purpose only and may vary on actual silicon. These values are
> +		 * considered just to demonstrate that the cpuidle governor
> +		 * logic works.
> +		 */
> +		idle-states {
> +			entry-method = "psci";
> +
> +			CPU_SLEEP: cpu-sleep {
> +				compatible = "arm,idle-state";
> +				arm,psci-suspend-param = <0x0010000>;
> +				local-timer-stop;
> +				entry-latency-us = <800>;
> +				exit-latency-us = <3200>;
> +				min-residency-us = <4200>;
> +			};
> +			CLUSTER_SLEEP: cluster-sleep {
> +				compatible = "arm,idle-state";
> +				arm,psci-suspend-param = <0x1010000>;
> +				local-timer-stop;
> +				entry-latency-us = <1000>;
> +				exit-latency-us = <3200>;
> +				min-residency-us = <4500>;
> +			};
> +		};
> +
> +		cpu-map {
> +
> +			cluster0 {
> +
> +				core0 {
> +					cpu = <&CPU0>;
> +				};
> +
> +				core1 {
> +					cpu = <&CPU1>;
> +				};
> +
> +				core2 {
> +					cpu = <&CPU2>;
> +				};
> +
> +				core3 {
> +					cpu = <&CPU3>;
> +				};
> +			};
> +
> +			cluster1 {
> +
> +				core0 {
> +					cpu = <&CPU4>;
> +				};
> +
> +				core1 {
> +					cpu = <&CPU5>;
> +				};
> +
> +				core2 {
> +					cpu = <&CPU6>;
> +				};
> +
> +				core3 {
> +					cpu = <&CPU7>;
> +				};
> +			};
> +
> +			cluster2 {
> +
> +				core0 {
> +					cpu = <&CPU8>;
> +				};
> +
> +				core1 {
> +					cpu = <&CPU9>;
> +				};
> +
> +				core2 {
> +					cpu = <&CPU10>;
> +				};
> +
> +				core3 {
> +					cpu = <&CPU11>;
> +				};
> +			};
> +
> +			cluster3 {
> +
> +				core0 {
> +					cpu = <&CPU12>;
> +				};
> +
> +				core1 {
> +					cpu = <&CPU13>;
> +				};
> +
> +				core2 {
> +					cpu = <&CPU14>;
> +				};
> +
> +				core3 {
> +					cpu = <&CPU15>;
> +				};
> +			};
> +		};
> +
> +		CPU0: cpu@0 {
> +			device_type = "cpu";
> +			compatible = "arm,cortex-a720ae";
> +			reg = <0x00 0x00>;
> +			enable-method = "psci";
> +			i-cache-size = <0x10000>;
> +			i-cache-line-size = <0x40>;
> +			i-cache-sets = <0x100>;

So for those numbers that are meaningful in decimal (64 bytes cache line,
256 sets), I think it's better to express them in decimal directly.
For the small size here you could do it as well, though for the bigger
sizes (L2 and L3 below) it's probably better left in hex.

> +			d-cache-size = <0x10000>;
> +			d-cache-line-size = <0x40>;
> +			d-cache-sets = <0x100>;
> +			clocks = <&scmi_dvfs 0x00>;
> +			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
> +			next-level-cache = <&CL0_L2_0>;
> +
> +			CL0_L2_0: l2-cache {
> +				compatible = "cache";
> +				cache-unified;
> +				cache-level = <0x02>;

Same here, cache-level should be just <2>.

> +				/* 512KB */
> +				cache-size = <0x80000>;

Please add the comment right behind the number, that disrupts the flow
less, I feel.

> +				/* 64B */
> +				cache-line-size = <0x40>;

... and as above, just write <64>, also allows you to lose the comment.

> +				/* 8-way set */
> +				cache-sets = <0x400>;
> +				next-level-cache = <&CL0_L3>;
> +			};
> +		};
> +
> +		CPU1: cpu@100 {
> +			device_type = "cpu";
> +			compatible = "arm,cortex-a720ae";
> +			reg = <0x00 0x100>;

for the records: I verified that the other CPU nodes are the same, except
for their obvious differences in cache numbers and MPIDRs.

<snip>

> +
> +		CL0_L3: l3-cache0 {
> +			compatible = "cache";
> +			cache-unified;
> +			cache-level = <0x03>;
> +			/* 4MB */
> +			cache-size = <0x400000>;
> +			/* 64B */
> +			cache-line-size = <0x40>;
> +			/* 16-way set */
> +			cache-sets = <0x1000>;
> +		};
> +
> +		CL1_L3: l3-cache1 {
> +			compatible = "cache";
> +			cache-unified;
> +			cache-level = <0x03>;
> +			/* 4MB */
> +			cache-size = <0x400000>;
> +			/* 64B */
> +			cache-line-size = <0x40>;
> +			/* 16-way set */
> +			cache-sets = <0x1000>;
> +		};
> +
> +		CL2_L3: l3-cache2 {
> +			compatible = "cache";
> +			cache-unified;
> +			cache-level = <0x03>;
> +			/* 4MB */
> +			cache-size = <0x400000>;
> +			/* 64B */
> +			cache-line-size = <0x40>;
> +			/* 16-way set */
> +			cache-sets = <0x1000>;
> +		};
> +
> +		CL3_L3: l3-cache3 {
> +			compatible = "cache";
> +			cache-unified;
> +			cache-level = <0x03>;
> +			/* 4MB */
> +			cache-size = <0x400000>;
> +			/* 64B */
> +			cache-line-size = <0x40>;
> +			/* 16-way set */
> +			cache-sets = <0x1000>;
> +		};
> +	};
> +
> +	dsu-pmu-0 {
> +		compatible = "arm,dsu-pmu";
> +		cpus = <&CPU0 &CPU1 &CPU2 &CPU3>;
> +		interrupts = <GIC_SPI 216 IRQ_TYPE_EDGE_RISING>;

Shouldn't that IRQ number be 184? According to the (internal) IRQ
map document this lists 216 as the GIC interrupt ID, but the SPI ID would
then need to be 32 less, so 184 (the column next to it in the spreadsheet).
Same for the other DSU PMUs, but the other SPIs seem to be correct (timer,
UART, ...).

> +	};
> +
> +	dsu-pmu-1 {
> +		compatible = "arm,dsu-pmu";
> +		cpus = <&CPU4 &CPU5 &CPU6 &CPU7>;
> +		interrupts = <GIC_SPI 217 IRQ_TYPE_EDGE_RISING>;
> +	};
> +
> +	dsu-pmu-2 {
> +		compatible = "arm,dsu-pmu";
> +		cpus = <&CPU8 &CPU9 &CPU10 &CPU11>;
> +		interrupts = <GIC_SPI 218 IRQ_TYPE_EDGE_RISING>;
> +	};
> +
> +	dsu-pmu-3 {
> +		compatible = "arm,dsu-pmu";
> +		cpus = <&CPU12 &CPU13 &CPU14 &CPU15>;
> +		interrupts = <GIC_SPI 219 IRQ_TYPE_EDGE_RISING>;
> +	};
> +
> +	memory@80000000 {
> +		device_type = "memory";
> +
> +		/* Bank 0: start = 0x0000_0000_8000_0000, size = ~2 GiB (0x7F00_0000) */

That comment is somewhat redundant, as it mirrors the line below.
If we need a comment, I'd suggest something like: ~2GB mapped at 2GB,
another 2GB at 2TB.

> +		reg = <
> +			0x00000000  0x80000000  0x00000000  0x7F000000
> +			0x00000200  0x00000000  0x00000000  0x80000000
> +		>;
> +	};
> +
> +	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>,
> +			<GIC_PPI 12 IRQ_TYPE_LEVEL_LOW>;
> +	};
> +
> +	soc_clk24mhz: clock-24000000 {
> +		compatible = "fixed-clock";
> +		#clock-cells = <0>;
> +		clock-frequency = <24000000>;
> +		clock-output-names = "refclk24mhz";
> +	};
> +
> +	soc: soc {
> +		compatible = "simple-bus";
> +		#address-cells = <2>;
> +		#size-cells = <2>;
> +		ranges;
> +
> +		timer@1a810000 {
> +			compatible = "arm,armv7-timer-mem";
> +			reg = <0x0 0x1a810000 0 0x10000>;
> +			#address-cells = <1>;
> +			#size-cells = <1>;
> +			/* Map child space [0x0..0x30000) to parent @ 0x1a810000 */
> +			ranges = <0x0 0x0 0x1a810000 0x00030000>;
> +
> +			frame@20000 {
> +				frame-number = <0>;
> +				interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
> +				reg = <0x20000 0x10000>;
> +			};
> +		};
> +
> +		gic: interrupt-controller@20800000 {
> +			compatible = "arm,gic-v3";
> +			#redistributor-regions = <16>;
> +			reg = <0x0 0x20800000 0x0 0x10000>,    /* GICD */
> +				<0x0 0x20880000 0x0 0x40000>,    /* 16 * GICR */
> +				<0x0 0x208c0000 0x0 0x40000>,

Those look as if they are all contiguous, aren't they?
Then you wouldn't need the #redistributor-regions property above, and can
just go with one big GICR region.

> +				<0x0 0x20900000 0x0 0x40000>,
> +				<0x0 0x20940000 0x0 0x40000>,
> +				<0x0 0x20980000 0x0 0x40000>,
> +				<0x0 0x209c0000 0x0 0x40000>,
> +				<0x0 0x20a00000 0x0 0x40000>,
> +				<0x0 0x20a40000 0x0 0x40000>,
> +				<0x0 0x20a80000 0x0 0x40000>,
> +				<0x0 0x20ac0000 0x0 0x40000>,
> +				<0x0 0x20b00000 0x0 0x40000>,
> +				<0x0 0x20b40000 0x0 0x40000>,
> +				<0x0 0x20b80000 0x0 0x40000>,
> +				<0x0 0x20bc0000 0x0 0x40000>,
> +				<0x0 0x20c00000 0x0 0x40000>,
> +				<0x0 0x20c40000 0x0 0x40000>;
> +			#interrupt-cells = <3>;
> +			#address-cells = <2>;
> +			#size-cells = <2>;
> +			ranges;
> +			interrupt-controller;
> +			interrupts = <GIC_PPI 9 IRQ_TYPE_LEVEL_HIGH>;
> +
> +			its1: msi-controller@20840000 {

Are there multiple ITSes, and some are just not shown here?
If not, please just use "its" as the label name.

> +				compatible = "arm,gic-v3-its";
> +				reg = <0x0 0x20840000 0x0 0x40000>;
> +				msi-controller;
> +				#msi-cells = <1>;
> +			};
> +		};
> +
> +		/* UART is fixed as 24MHz, both UARTCLK and PCLK */
> +		soc_serial0: serial@1a400000 {
> +			compatible = "arm,pl011", "arm,primecell";
> +			reg = <0x0 0x1a400000 0x0 0x10000>;
> +			interrupts = <GIC_SPI 52 IRQ_TYPE_LEVEL_HIGH>;
> +			clocks = <&soc_clk24mhz>, <&soc_clk24mhz>;
> +			clock-names = "uartclk", "apb_pclk";
> +		};
> +
> +		watchdog@1a420000 {
> +			compatible = "arm,sbsa-gwdt";
> +			reg = <0x0 0x1a420000 0x0 0x10000>,
> +			      <0x0 0x1a430000 0x0 0x10000>;
> +			interrupts = <GIC_SPI 50 IRQ_TYPE_LEVEL_HIGH>;
> +		};
> +
> +		rtc@300d0000 {
> +			compatible = "arm,pl031", "arm,primecell";
> +			reg = <0x0 0x300d0000 0x0 0x10000>;
> +			interrupts = <GIC_SPI 268 IRQ_TYPE_LEVEL_HIGH>;

Can you please double check this interrupt ID? The IRQ mapping document
just lists some "expansion range" here, but I cannot verify if this is
using the SPI offset of 32 or not.

> +			clocks = <&soc_clk24mhz>;
> +			clock-names = "apb_pclk";
> +		};
> +
> +	};
> +
> +	psci {
> +		compatible = "arm,psci-1.0", "arm,psci-0.2", "arm,psci";

You don't need compatibility to the pre 0.2 PSCI standard, so drop the
last compatible name.

> +		method = "smc";
> +		cpu_suspend = <0xc4000001>;
> +		cpu_off = <0x84000002>;
> +		cpu_on = <0xc4000003>;

And those three function IDs are only needed for this pre-0.2 name, so you
can remove them.

> +	};
> +
> +	sram: sram@104000 {
> +		compatible = "mmio-sram";
> +		reg = <0x0 0x104000 0x0 0x00001000>;
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges = <0 0x0 0x104000 0x00001000>;
> +
> +		scmi_shmem_tx: scpshmem-sram-section@0 {
> +			compatible = "arm,scmi-shmem";
> +			reg = <0x0 0x100>;
> +		};
> +		scmi_shmem_rx: scpshmem-sram-section@100 {
> +			compatible = "arm,scmi-shmem";
> +			reg = <0x100 0x100>;
> +		};
> +	};
> +
> +	mbox_db_tx: mailbox@40020000 {
> +		compatible = "arm,mhuv3";
> +		reg = <0x0 0x40020000 0x0 0x30000>;
> +		clocks = <&soc_clk24mhz>;
> +		#mbox-cells = <3>;
> +		interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>;
> +		interrupt-names = "combined";
> +	};
> +
> +	mbox_db_rx: mailbox@40060000 {
> +		compatible = "arm,mhuv3";
> +		reg = <0x0 0x40060000 0x0 0x30000>;
> +		clocks = <&soc_clk24mhz>;
> +		#mbox-cells = <3>;
> +		interrupts = <GIC_SPI 113 IRQ_TYPE_LEVEL_HIGH>;
> +		interrupt-names = "combined";
> +	};
> +
> +	firmware {
> +		scmi {
> +			compatible = "arm,scmi";
> +			mbox-names = "tx", "rx";
> +			mboxes = <&mbox_db_tx 0 0 0 &mbox_db_rx 0 0 0 &mbox_db_rx 0 0 2>;

What is this third mailbox about? I think this would have to match
mbox-names also? I guess this is not needed?

Cheers,
Andre

> +			shmem = <&scmi_shmem_tx &scmi_shmem_rx>;
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			scmi_dvfs: protocol@13 {
> +				reg = <0x13>;
> +				#clock-cells = <1>;
> +			};
> +		};
> +	};
> +};
> 

Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Debbie Horsfall]

On 27/01/2026 13:22, Andre Przywara wrote:
> On Fri, 23 Jan 2026 17:37:47 +0000
> Debbie Horsfall <debbie.horsfall@arm.com> wrote:
> 
> Hi Debbie,
> 
> thanks for taking the time to send this upstream!
>

Thank you for reviewing it! I have responded to all of your points and 
will send a v2 patch set.


>> Introduce the Zena CSS Fixed Virtual Platform (FVP) dts. This is
>> currently the only Zena CSS variant, however the common definitions are
>> included in a common dtsi for extensibility.
>>
>> Signed-off-by: Debbie Horsfall <debbie.horsfall@arm.com>
>> ---
>>   MAINTAINERS                              |   1 +
>>   arch/arm64/boot/dts/arm/Makefile         |   1 +
>>   arch/arm64/boot/dts/arm/zena-css-fvp.dts |  55 ++
>>   arch/arm64/boot/dts/arm/zena-css.dtsi    | 826 +++++++++++++++++++++++++++++++
>>   4 files changed, 883 insertions(+)
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 90d88137adf1..d1d2dae6a71e 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -3727,6 +3727,7 @@ ARM/ZENA CSS PLATFORM
>>   M:	Debbie Horsfall <debbie.horsfall@arm.com>
>>   S:	Maintained
>>   F:	Documentation/devicetree/bindings/arm/arm,zena-css.yaml
>> +F:	arch/arm64/boot/dts/arm/zena-css*
>>   
>>   ARM/ZYNQ ARCHITECTURE
>>   M:	Michal Simek <michal.simek@amd.com>
>> diff --git a/arch/arm64/boot/dts/arm/Makefile b/arch/arm64/boot/dts/arm/Makefile
>> index f30ee045dc95..770fb145b4a9 100644
>> --- a/arch/arm64/boot/dts/arm/Makefile
>> +++ b/arch/arm64/boot/dts/arm/Makefile
>> @@ -8,3 +8,4 @@ dtb-$(CONFIG_ARCH_VEXPRESS) += vexpress-v2f-1xv7-ca53x2.dtb
>>   dtb-$(CONFIG_ARCH_VEXPRESS) += fvp-base-revc.dtb
>>   dtb-$(CONFIG_ARCH_VEXPRESS) += corstone1000-fvp.dtb corstone1000-mps3.dtb
>>   dtb-$(CONFIG_ARCH_VEXPRESS) += morello-sdp.dtb morello-fvp.dtb
>> +dtb-$(CONFIG_ARCH_VEXPRESS) += zena-css-fvp.dtb
>> diff --git a/arch/arm64/boot/dts/arm/zena-css-fvp.dts b/arch/arm64/boot/dts/arm/zena-css-fvp.dts
>> new file mode 100644
>> index 000000000000..d3c649e894d1
>> --- /dev/null
>> +++ b/arch/arm64/boot/dts/arm/zena-css-fvp.dts
>> @@ -0,0 +1,55 @@
>> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
>> +/*
>> + * Copyright (c) 2025, Arm Limited. All rights reserved.
>> + */
>> +
>> +/dts-v1/;
>> +
>> +#include "zena-css.dtsi"
>> +
>> +/ {
>> +	model = "Zena CSS Fixed Virtual Platform";
>> +	compatible = "arm,zena-css-fvp", "arm,zena-css";
>> +
>> +	chosen {
>> +		stdout-path = &soc_serial0;
>> +	};
>> +};
>> +
>> +&soc {
>> +	virtio@30060000 {
>> +		compatible = "virtio,mmio";
>> +		reg = <0x0 0x30060000 0x0 0x10000>;
>> +		interrupts = <GIC_SPI 261 IRQ_TYPE_LEVEL_HIGH>;
>> +	};
>> +
>> +	virtio@30020000 {
> 
> I think the nodes should be ordered by their address. Do you make any
> assumptions about naming of devices (/dev/vda, /dev/vdb) in your setup?
> 

I will move virtio@30060000 into order. I don't think there are any 
assumptions on device naming dependent on ordering but I will run all of 
our tests with them in address order to check.

>> +		compatible = "virtio,mmio";
>> +		reg = <0x0 0x30020000 0x0 0x10000>;
>> +		interrupts = <GIC_SPI 257 IRQ_TYPE_LEVEL_HIGH>;
>> +	};
>> +
>> +	virtio@30030000 {
>> +		compatible = "virtio,mmio";
>> +		reg = <0x0 0x30030000 0x0 0x10000>;
>> +		interrupts = <GIC_SPI 258 IRQ_TYPE_LEVEL_HIGH>;
>> +	};
>> +
>> +	virtio@30040000 {
>> +		compatible = "virtio,mmio";
>> +		reg = <0x0 0x30040000 0x0 0x10000>;
>> +		interrupts = <GIC_SPI 259 IRQ_TYPE_LEVEL_HIGH>;
>> +	};
>> +
>> +	virtio@30050000 {
>> +		compatible = "virtio,mmio";
>> +		reg = <0x0 0x30050000 0x0 0x10000>;
>> +		interrupts = <GIC_SPI 260 IRQ_TYPE_LEVEL_HIGH>;
>> +	};
>> +
> 
> Do you know if there is something at 0x30070000? Maybe something that
> needs explicit enablement on the model command line? In this case we might
> want a comment here.
> 

The memory map documentation says there is no device there.

>> +	virtio@30080000 {
>> +		compatible = "virtio,mmio";
>> +		reg = <0x0 0x30080000 0x0 0x10000>;
>> +		interrupts = <GIC_SPI 263 IRQ_TYPE_LEVEL_HIGH>;
>> +	};
>> +};
>> diff --git a/arch/arm64/boot/dts/arm/zena-css.dtsi b/arch/arm64/boot/dts/arm/zena-css.dtsi
>> new file mode 100644
>> index 000000000000..7825e93df0a6
>> --- /dev/null
>> +++ b/arch/arm64/boot/dts/arm/zena-css.dtsi
>> @@ -0,0 +1,826 @@
>> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
>> +/*
>> + * Copyright (c) 2025, Arm Limited. All rights reserved.
>> + */
>> +
>> +#include <dt-bindings/interrupt-controller/arm-gic.h>
>> +
>> +/ {
>> +	interrupt-parent = <&gic>;
>> +	#address-cells = <2>;
>> +	#size-cells = <2>;
>> +
>> +	cpus {
>> +		#address-cells = <2>;
>> +		#size-cells = <0>;
>> +
>> +		/*
>> +		 * The latency and residency numbers below are for illustrative
>> +		 * purpose only and may vary on actual silicon. These values are
>> +		 * considered just to demonstrate that the cpuidle governor
>> +		 * logic works.
>> +		 */
>> +		idle-states {
>> +			entry-method = "psci";
>> +
>> +			CPU_SLEEP: cpu-sleep {
>> +				compatible = "arm,idle-state";
>> +				arm,psci-suspend-param = <0x0010000>;
>> +				local-timer-stop;
>> +				entry-latency-us = <800>;
>> +				exit-latency-us = <3200>;
>> +				min-residency-us = <4200>;
>> +			};
>> +			CLUSTER_SLEEP: cluster-sleep {
>> +				compatible = "arm,idle-state";
>> +				arm,psci-suspend-param = <0x1010000>;
>> +				local-timer-stop;
>> +				entry-latency-us = <1000>;
>> +				exit-latency-us = <3200>;
>> +				min-residency-us = <4500>;
>> +			};
>> +		};
>> +
>> +		cpu-map {
>> +
>> +			cluster0 {
>> +
>> +				core0 {
>> +					cpu = <&CPU0>;
>> +				};
>> +
>> +				core1 {
>> +					cpu = <&CPU1>;
>> +				};
>> +
>> +				core2 {
>> +					cpu = <&CPU2>;
>> +				};
>> +
>> +				core3 {
>> +					cpu = <&CPU3>;
>> +				};
>> +			};
>> +
>> +			cluster1 {
>> +
>> +				core0 {
>> +					cpu = <&CPU4>;
>> +				};
>> +
>> +				core1 {
>> +					cpu = <&CPU5>;
>> +				};
>> +
>> +				core2 {
>> +					cpu = <&CPU6>;
>> +				};
>> +
>> +				core3 {
>> +					cpu = <&CPU7>;
>> +				};
>> +			};
>> +
>> +			cluster2 {
>> +
>> +				core0 {
>> +					cpu = <&CPU8>;
>> +				};
>> +
>> +				core1 {
>> +					cpu = <&CPU9>;
>> +				};
>> +
>> +				core2 {
>> +					cpu = <&CPU10>;
>> +				};
>> +
>> +				core3 {
>> +					cpu = <&CPU11>;
>> +				};
>> +			};
>> +
>> +			cluster3 {
>> +
>> +				core0 {
>> +					cpu = <&CPU12>;
>> +				};
>> +
>> +				core1 {
>> +					cpu = <&CPU13>;
>> +				};
>> +
>> +				core2 {
>> +					cpu = <&CPU14>;
>> +				};
>> +
>> +				core3 {
>> +					cpu = <&CPU15>;
>> +				};
>> +			};
>> +		};
>> +
>> +		CPU0: cpu@0 {
>> +			device_type = "cpu";
>> +			compatible = "arm,cortex-a720ae";
>> +			reg = <0x00 0x00>;
>> +			enable-method = "psci";
>> +			i-cache-size = <0x10000>;
>> +			i-cache-line-size = <0x40>;
>> +			i-cache-sets = <0x100>;
> 
> So for those numbers that are meaningful in decimal (64 bytes cache line,
> 256 sets), I think it's better to express them in decimal directly.
> For the small size here you could do it as well, though for the bigger
> sizes (L2 and L3 below) it's probably better left in hex.
> 

Will do.

>> +			d-cache-size = <0x10000>;
>> +			d-cache-line-size = <0x40>;
>> +			d-cache-sets = <0x100>;
>> +			clocks = <&scmi_dvfs 0x00>;
>> +			cpu-idle-states = <&CPU_SLEEP &CLUSTER_SLEEP>;
>> +			next-level-cache = <&CL0_L2_0>;
>> +
>> +			CL0_L2_0: l2-cache {
>> +				compatible = "cache";
>> +				cache-unified;
>> +				cache-level = <0x02>;
> 
> Same here, cache-level should be just <2>.
> 

Will do.

>> +				/* 512KB */
>> +				cache-size = <0x80000>;
> 
> Please add the comment right behind the number, that disrupts the flow
> less, I feel.
> 

Will do

>> +				/* 64B */
>> +				cache-line-size = <0x40>;
> 
> ... and as above, just write <64>, also allows you to lose the comment.
> 

Will do.

>> +				/* 8-way set */
>> +				cache-sets = <0x400>;
>> +				next-level-cache = <&CL0_L3>;
>> +			};
>> +		};
>> +
>> +		CPU1: cpu@100 {
>> +			device_type = "cpu";
>> +			compatible = "arm,cortex-a720ae";
>> +			reg = <0x00 0x100>;
> 
> for the records: I verified that the other CPU nodes are the same, except
> for their obvious differences in cache numbers and MPIDRs.
> 
> <snip>
> 

Thank you.

>> +
>> +		CL0_L3: l3-cache0 {
>> +			compatible = "cache";
>> +			cache-unified;
>> +			cache-level = <0x03>;
>> +			/* 4MB */
>> +			cache-size = <0x400000>;
>> +			/* 64B */
>> +			cache-line-size = <0x40>;
>> +			/* 16-way set */
>> +			cache-sets = <0x1000>;
>> +		};
>> +
>> +		CL1_L3: l3-cache1 {
>> +			compatible = "cache";
>> +			cache-unified;
>> +			cache-level = <0x03>;
>> +			/* 4MB */
>> +			cache-size = <0x400000>;
>> +			/* 64B */
>> +			cache-line-size = <0x40>;
>> +			/* 16-way set */
>> +			cache-sets = <0x1000>;
>> +		};
>> +
>> +		CL2_L3: l3-cache2 {
>> +			compatible = "cache";
>> +			cache-unified;
>> +			cache-level = <0x03>;
>> +			/* 4MB */
>> +			cache-size = <0x400000>;
>> +			/* 64B */
>> +			cache-line-size = <0x40>;
>> +			/* 16-way set */
>> +			cache-sets = <0x1000>;
>> +		};
>> +
>> +		CL3_L3: l3-cache3 {
>> +			compatible = "cache";
>> +			cache-unified;
>> +			cache-level = <0x03>;
>> +			/* 4MB */
>> +			cache-size = <0x400000>;
>> +			/* 64B */
>> +			cache-line-size = <0x40>;
>> +			/* 16-way set */
>> +			cache-sets = <0x1000>;
>> +		};
>> +	};
>> +
>> +	dsu-pmu-0 {
>> +		compatible = "arm,dsu-pmu";
>> +		cpus = <&CPU0 &CPU1 &CPU2 &CPU3>;
>> +		interrupts = <GIC_SPI 216 IRQ_TYPE_EDGE_RISING>;
> 
> Shouldn't that IRQ number be 184? According to the (internal) IRQ
> map document this lists 216 as the GIC interrupt ID, but the SPI ID would
> then need to be 32 less, so 184 (the column next to it in the spreadsheet).
> Same for the other DSU PMUs, but the other SPIs seem to be correct (timer,
> UART, ...).
> 

Thank you for noticing this - it is an issue but wasn't picked up by our 
tests. I will change them.

>> +	};
>> +
>> +	dsu-pmu-1 {
>> +		compatible = "arm,dsu-pmu";
>> +		cpus = <&CPU4 &CPU5 &CPU6 &CPU7>;
>> +		interrupts = <GIC_SPI 217 IRQ_TYPE_EDGE_RISING>;
>> +	};
>> +
>> +	dsu-pmu-2 {
>> +		compatible = "arm,dsu-pmu";
>> +		cpus = <&CPU8 &CPU9 &CPU10 &CPU11>;
>> +		interrupts = <GIC_SPI 218 IRQ_TYPE_EDGE_RISING>;
>> +	};
>> +
>> +	dsu-pmu-3 {
>> +		compatible = "arm,dsu-pmu";
>> +		cpus = <&CPU12 &CPU13 &CPU14 &CPU15>;
>> +		interrupts = <GIC_SPI 219 IRQ_TYPE_EDGE_RISING>;
>> +	};
>> +
>> +	memory@80000000 {
>> +		device_type = "memory";
>> +
>> +		/* Bank 0: start = 0x0000_0000_8000_0000, size = ~2 GiB (0x7F00_0000) */
> 
> That comment is somewhat redundant, as it mirrors the line below.
> If we need a comment, I'd suggest something like: ~2GB mapped at 2GB,
> another 2GB at 2TB.
> 

Thanks, I will take the new comment suggestion.

>> +		reg = <
>> +			0x00000000  0x80000000  0x00000000  0x7F000000
>> +			0x00000200  0x00000000  0x00000000  0x80000000
>> +		>;
>> +	};
>> +
>> +	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>,
>> +			<GIC_PPI 12 IRQ_TYPE_LEVEL_LOW>;
>> +	};
>> +
>> +	soc_clk24mhz: clock-24000000 {
>> +		compatible = "fixed-clock";
>> +		#clock-cells = <0>;
>> +		clock-frequency = <24000000>;
>> +		clock-output-names = "refclk24mhz";
>> +	};
>> +
>> +	soc: soc {
>> +		compatible = "simple-bus";
>> +		#address-cells = <2>;
>> +		#size-cells = <2>;
>> +		ranges;
>> +
>> +		timer@1a810000 {
>> +			compatible = "arm,armv7-timer-mem";
>> +			reg = <0x0 0x1a810000 0 0x10000>;
>> +			#address-cells = <1>;
>> +			#size-cells = <1>;
>> +			/* Map child space [0x0..0x30000) to parent @ 0x1a810000 */
>> +			ranges = <0x0 0x0 0x1a810000 0x00030000>;
>> +
>> +			frame@20000 {
>> +				frame-number = <0>;
>> +				interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
>> +				reg = <0x20000 0x10000>;
>> +			};
>> +		};
>> +
>> +		gic: interrupt-controller@20800000 {
>> +			compatible = "arm,gic-v3";
>> +			#redistributor-regions = <16>;
>> +			reg = <0x0 0x20800000 0x0 0x10000>,    /* GICD */
>> +				<0x0 0x20880000 0x0 0x40000>,    /* 16 * GICR */
>> +				<0x0 0x208c0000 0x0 0x40000>,
> 
> Those look as if they are all contiguous, aren't they?
> Then you wouldn't need the #redistributor-regions property above, and can
> just go with one big GICR region.
> 

This is a workaround for the AP GIC Multiview. Is it acceptable?

>> +				<0x0 0x20900000 0x0 0x40000>,
>> +				<0x0 0x20940000 0x0 0x40000>,
>> +				<0x0 0x20980000 0x0 0x40000>,
>> +				<0x0 0x209c0000 0x0 0x40000>,
>> +				<0x0 0x20a00000 0x0 0x40000>,
>> +				<0x0 0x20a40000 0x0 0x40000>,
>> +				<0x0 0x20a80000 0x0 0x40000>,
>> +				<0x0 0x20ac0000 0x0 0x40000>,
>> +				<0x0 0x20b00000 0x0 0x40000>,
>> +				<0x0 0x20b40000 0x0 0x40000>,
>> +				<0x0 0x20b80000 0x0 0x40000>,
>> +				<0x0 0x20bc0000 0x0 0x40000>,
>> +				<0x0 0x20c00000 0x0 0x40000>,
>> +				<0x0 0x20c40000 0x0 0x40000>;
>> +			#interrupt-cells = <3>;
>> +			#address-cells = <2>;
>> +			#size-cells = <2>;
>> +			ranges;
>> +			interrupt-controller;
>> +			interrupts = <GIC_PPI 9 IRQ_TYPE_LEVEL_HIGH>;
>> +
>> +			its1: msi-controller@20840000 {
> 
> Are there multiple ITSes, and some are just not shown here?
> If not, please just use "its" as the label name.
> 

There's only one so I'll rename it.

>> +				compatible = "arm,gic-v3-its";
>> +				reg = <0x0 0x20840000 0x0 0x40000>;
>> +				msi-controller;
>> +				#msi-cells = <1>;
>> +			};
>> +		};
>> +
>> +		/* UART is fixed as 24MHz, both UARTCLK and PCLK */
>> +		soc_serial0: serial@1a400000 {
>> +			compatible = "arm,pl011", "arm,primecell";
>> +			reg = <0x0 0x1a400000 0x0 0x10000>;
>> +			interrupts = <GIC_SPI 52 IRQ_TYPE_LEVEL_HIGH>;
>> +			clocks = <&soc_clk24mhz>, <&soc_clk24mhz>;
>> +			clock-names = "uartclk", "apb_pclk";
>> +		};
>> +
>> +		watchdog@1a420000 {
>> +			compatible = "arm,sbsa-gwdt";
>> +			reg = <0x0 0x1a420000 0x0 0x10000>,
>> +			      <0x0 0x1a430000 0x0 0x10000>;
>> +			interrupts = <GIC_SPI 50 IRQ_TYPE_LEVEL_HIGH>;
>> +		};
>> +
>> +		rtc@300d0000 {
>> +			compatible = "arm,pl031", "arm,primecell";
>> +			reg = <0x0 0x300d0000 0x0 0x10000>;
>> +			interrupts = <GIC_SPI 268 IRQ_TYPE_LEVEL_HIGH>;
> 
> Can you please double check this interrupt ID? The IRQ mapping document
> just lists some "expansion range" here, but I cannot verify if this is
> using the SPI offset of 32 or not.
> 

I have confirmed with our interrupt map.

>> +			clocks = <&soc_clk24mhz>;
>> +			clock-names = "apb_pclk";
>> +		};
>> +
>> +	};
>> +
>> +	psci {
>> +		compatible = "arm,psci-1.0", "arm,psci-0.2", "arm,psci";
> 
> You don't need compatibility to the pre 0.2 PSCI standard, so drop the
> last compatible name.
> 

I will remove this.

>> +		method = "smc";
>> +		cpu_suspend = <0xc4000001>;
>> +		cpu_off = <0x84000002>;
>> +		cpu_on = <0xc4000003>;
> 
> And those three function IDs are only needed for this pre-0.2 name, so you
> can remove them.
> 

I will remove them.

>> +	};
>> +
>> +	sram: sram@104000 {
>> +		compatible = "mmio-sram";
>> +		reg = <0x0 0x104000 0x0 0x00001000>;
>> +		#address-cells = <1>;
>> +		#size-cells = <1>;
>> +		ranges = <0 0x0 0x104000 0x00001000>;
>> +
>> +		scmi_shmem_tx: scpshmem-sram-section@0 {
>> +			compatible = "arm,scmi-shmem";
>> +			reg = <0x0 0x100>;
>> +		};
>> +		scmi_shmem_rx: scpshmem-sram-section@100 {
>> +			compatible = "arm,scmi-shmem";
>> +			reg = <0x100 0x100>;
>> +		};
>> +	};
>> +
>> +	mbox_db_tx: mailbox@40020000 {
>> +		compatible = "arm,mhuv3";
>> +		reg = <0x0 0x40020000 0x0 0x30000>;
>> +		clocks = <&soc_clk24mhz>;
>> +		#mbox-cells = <3>;
>> +		interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>;
>> +		interrupt-names = "combined";
>> +	};
>> +
>> +	mbox_db_rx: mailbox@40060000 {
>> +		compatible = "arm,mhuv3";
>> +		reg = <0x0 0x40060000 0x0 0x30000>;
>> +		clocks = <&soc_clk24mhz>;
>> +		#mbox-cells = <3>;
>> +		interrupts = <GIC_SPI 113 IRQ_TYPE_LEVEL_HIGH>;
>> +		interrupt-names = "combined";
>> +	};
>> +
>> +	firmware {
>> +		scmi {
>> +			compatible = "arm,scmi";
>> +			mbox-names = "tx", "rx";
>> +			mboxes = <&mbox_db_tx 0 0 0 &mbox_db_rx 0 0 0 &mbox_db_rx 0 0 2>;
> 
> What is this third mailbox about? I think this would have to match
> mbox-names also? I guess this is not needed?
> 

The team is confirming which mbox names are appropriate. To pass the 
Devicetree validation the only valid combination of three is: "tx", 
"tx_reply", "rx". However, the second mbox needs to be rx else the SCMI 
communication fails. I'll investigate further and make sure the names match.

> Cheers,
> Andre
> 
>> +			shmem = <&scmi_shmem_tx &scmi_shmem_rx>;
>> +			#address-cells = <1>;
>> +			#size-cells = <0>;
>> +
>> +			scmi_dvfs: protocol@13 {
>> +				reg = <0x13>;
>> +				#clock-cells = <1>;
>> +			};
>> +		};
>> +	};
>> +};
>>
> 


-- 

Kind regards,
Debbie

Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Andre Przywara]

Hi Debbie,

On 1/30/26 10:58, Debbie Horsfall wrote:
> On 27/01/2026 13:22, Andre Przywara wrote:
>> On Fri, 23 Jan 2026 17:37:47 +0000
>> Debbie Horsfall <debbie.horsfall@arm.com> wrote:
>>
>> Hi Debbie,
>>
>> thanks for taking the time to send this upstream!
>>
> 
> Thank you for reviewing it! I have responded to all of your points and 
> will send a v2 patch set.
> 
> 
>>> Introduce the Zena CSS Fixed Virtual Platform (FVP) dts. This is
>>> currently the only Zena CSS variant, however the common definitions are
>>> included in a common dtsi for extensibility.
>>>
>>> Signed-off-by: Debbie Horsfall <debbie.horsfall@arm.com>
>>> ---
>>>   MAINTAINERS                              |   1 +
>>>   arch/arm64/boot/dts/arm/Makefile         |   1 +
>>>   arch/arm64/boot/dts/arm/zena-css-fvp.dts |  55 ++
>>>   arch/arm64/boot/dts/arm/zena-css.dtsi    | 826 ++++++++++++++++++++ 
>>> +++++++++++
>>>   4 files changed, 883 insertions(+)
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index 90d88137adf1..d1d2dae6a71e 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -3727,6 +3727,7 @@ ARM/ZENA CSS PLATFORM
>>>   M:    Debbie Horsfall <debbie.horsfall@arm.com>
>>>   S:    Maintained
>>>   F:    Documentation/devicetree/bindings/arm/arm,zena-css.yaml
>>> +F:    arch/arm64/boot/dts/arm/zena-css*
>>>   ARM/ZYNQ ARCHITECTURE
>>>   M:    Michal Simek <michal.simek@amd.com>
>>> diff --git a/arch/arm64/boot/dts/arm/Makefile b/arch/arm64/boot/dts/ 
>>> arm/Makefile
>>> index f30ee045dc95..770fb145b4a9 100644
>>> --- a/arch/arm64/boot/dts/arm/Makefile
>>> +++ b/arch/arm64/boot/dts/arm/Makefile
>>> @@ -8,3 +8,4 @@ dtb-$(CONFIG_ARCH_VEXPRESS) += vexpress-v2f-1xv7- 
>>> ca53x2.dtb
>>>   dtb-$(CONFIG_ARCH_VEXPRESS) += fvp-base-revc.dtb
>>>   dtb-$(CONFIG_ARCH_VEXPRESS) += corstone1000-fvp.dtb corstone1000- 
>>> mps3.dtb
>>>   dtb-$(CONFIG_ARCH_VEXPRESS) += morello-sdp.dtb morello-fvp.dtb
>>> +dtb-$(CONFIG_ARCH_VEXPRESS) += zena-css-fvp.dtb
>>> diff --git a/arch/arm64/boot/dts/arm/zena-css-fvp.dts b/arch/arm64/ 
>>> boot/dts/arm/zena-css-fvp.dts
>>> new file mode 100644
>>> index 000000000000..d3c649e894d1
>>> --- /dev/null
>>> +++ b/arch/arm64/boot/dts/arm/zena-css-fvp.dts
>>> @@ -0,0 +1,55 @@
>>> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
>>> +/*
>>> + * Copyright (c) 2025, Arm Limited. All rights reserved.
>>> + */
>>> +
>>> +/dts-v1/;
>>> +
>>> +#include "zena-css.dtsi"
>>> +
>>> +/ {
>>> +    model = "Zena CSS Fixed Virtual Platform";
>>> +    compatible = "arm,zena-css-fvp", "arm,zena-css";
>>> +
>>> +    chosen {
>>> +        stdout-path = &soc_serial0;
>>> +    };
>>> +};
>>> +
>>> +&soc {
>>> +    virtio@30060000 {
>>> +        compatible = "virtio,mmio";
>>> +        reg = <0x0 0x30060000 0x0 0x10000>;
>>> +        interrupts = <GIC_SPI 261 IRQ_TYPE_LEVEL_HIGH>;
>>> +    };
>>> +
>>> +    virtio@30020000 {
>>
>> I think the nodes should be ordered by their address. Do you make any
>> assumptions about naming of devices (/dev/vda, /dev/vdb) in your setup?
>>
> 
> I will move virtio@30060000 into order. I don't think there are any 
> assumptions on device naming dependent on ordering but I will run all of 
> our tests with them in address order to check.

Thanks, that's good to know. I was afraid there was some cheeky 
assumption about /dev/vda pointing to a certain image or something ...

>>> +        compatible = "virtio,mmio";
>>> +        reg = <0x0 0x30020000 0x0 0x10000>;
>>> +        interrupts = <GIC_SPI 257 IRQ_TYPE_LEVEL_HIGH>;
>>> +    };
>>> +
>>> +    virtio@30030000 {
>>> +        compatible = "virtio,mmio";
>>> +        reg = <0x0 0x30030000 0x0 0x10000>;
>>> +        interrupts = <GIC_SPI 258 IRQ_TYPE_LEVEL_HIGH>;
>>> +    };
>>> +
>>> +    virtio@30040000 {
>>> +        compatible = "virtio,mmio";
>>> +        reg = <0x0 0x30040000 0x0 0x10000>;
>>> +        interrupts = <GIC_SPI 259 IRQ_TYPE_LEVEL_HIGH>;
>>> +    };
>>> +
>>> +    virtio@30050000 {
>>> +        compatible = "virtio,mmio";
>>> +        reg = <0x0 0x30050000 0x0 0x10000>;
>>> +        interrupts = <GIC_SPI 260 IRQ_TYPE_LEVEL_HIGH>;
>>> +    };
>>> +
>>
>> Do you know if there is something at 0x30070000? Maybe something that
>> needs explicit enablement on the model command line? In this case we 
>> might
>> want a comment here.
>>
> 
> The memory map documentation says there is no device there.

Good, thanks for checking.

> 
>>> +    virtio@30080000 {
>>> +        compatible = "virtio,mmio";
>>> +        reg = <0x0 0x30080000 0x0 0x10000>;
>>> +        interrupts = <GIC_SPI 263 IRQ_TYPE_LEVEL_HIGH>;
>>> +    };
>>> +};
>>> diff --git a/arch/arm64/boot/dts/arm/zena-css.dtsi b/arch/arm64/boot/ 
>>> dts/arm/zena-css.dtsi
>>> new file mode 100644
>>> index 000000000000..7825e93df0a6
>>> --- /dev/null
>>> +++ b/arch/arm64/boot/dts/arm/zena-css.dtsi
>>> @@ -0,0 +1,826 @@
>>> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
>>> +/*
>>> + * Copyright (c) 2025, Arm Limited. All rights reserved.
>>> + */

[ ... ]

>>> +
>>> +    soc: soc {
>>> +        compatible = "simple-bus";
>>> +        #address-cells = <2>;
>>> +        #size-cells = <2>;
>>> +        ranges;
>>> +
>>> +        timer@1a810000 {
>>> +            compatible = "arm,armv7-timer-mem";
>>> +            reg = <0x0 0x1a810000 0 0x10000>;
>>> +            #address-cells = <1>;
>>> +            #size-cells = <1>;
>>> +            /* Map child space [0x0..0x30000) to parent @ 0x1a810000 */
>>> +            ranges = <0x0 0x0 0x1a810000 0x00030000>;
>>> +
>>> +            frame@20000 {
>>> +                frame-number = <0>;
>>> +                interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
>>> +                reg = <0x20000 0x10000>;
>>> +            };
>>> +        };
>>> +
>>> +        gic: interrupt-controller@20800000 {
>>> +            compatible = "arm,gic-v3";
>>> +            #redistributor-regions = <16>;
>>> +            reg = <0x0 0x20800000 0x0 0x10000>,    /* GICD */
>>> +                <0x0 0x20880000 0x0 0x40000>,    /* 16 * GICR */
>>> +                <0x0 0x208c0000 0x0 0x40000>,
>>
>> Those look as if they are all contiguous, aren't they?
>> Then you wouldn't need the #redistributor-regions property above, and can
>> just go with one big GICR region.
>>
> 
> This is a workaround for the AP GIC Multiview. Is it acceptable?

Ah, right, sorry, I now remember, that's some automotive GIC, and this 
multiview feature causes the GICR_TYPER.Last bit not being correct, right?
In this case this is indeed a workaround, but you should add a comment 
here. Mention the GIC model (GIC-720AE?), and that its multiview feature 
causes the GICR_TYPER.Last bit not being as expected, so each core needs 
to gets its own redist region.

>>> +                <0x0 0x20900000 0x0 0x40000>,
>>> +                <0x0 0x20940000 0x0 0x40000>,
>>> +                <0x0 0x20980000 0x0 0x40000>,
>>> +                <0x0 0x209c0000 0x0 0x40000>,
>>> +                <0x0 0x20a00000 0x0 0x40000>,
>>> +                <0x0 0x20a40000 0x0 0x40000>,
>>> +                <0x0 0x20a80000 0x0 0x40000>,
>>> +                <0x0 0x20ac0000 0x0 0x40000>,
>>> +                <0x0 0x20b00000 0x0 0x40000>,
>>> +                <0x0 0x20b40000 0x0 0x40000>,
>>> +                <0x0 0x20b80000 0x0 0x40000>,
>>> +                <0x0 0x20bc0000 0x0 0x40000>,
>>> +                <0x0 0x20c00000 0x0 0x40000>,
>>> +                <0x0 0x20c40000 0x0 0x40000>;
>>> +            #interrupt-cells = <3>;
>>> +            #address-cells = <2>;
>>> +            #size-cells = <2>;
>>> +            ranges;
>>> +            interrupt-controller;
>>> +            interrupts = <GIC_PPI 9 IRQ_TYPE_LEVEL_HIGH>;
>>> +
>>> +            its1: msi-controller@20840000 {
>>
>> Are there multiple ITSes, and some are just not shown here?
>> If not, please just use "its" as the label name.
>>
> 
> There's only one so I'll rename it.
> 
>>> +                compatible = "arm,gic-v3-its";
>>> +                reg = <0x0 0x20840000 0x0 0x40000>;
>>> +                msi-controller;
>>> +                #msi-cells = <1>;
>>> +            };
>>> +        };
>>> +
>>> +        /* UART is fixed as 24MHz, both UARTCLK and PCLK */
>>> +        soc_serial0: serial@1a400000 {
>>> +            compatible = "arm,pl011", "arm,primecell";
>>> +            reg = <0x0 0x1a400000 0x0 0x10000>;
>>> +            interrupts = <GIC_SPI 52 IRQ_TYPE_LEVEL_HIGH>;
>>> +            clocks = <&soc_clk24mhz>, <&soc_clk24mhz>;
>>> +            clock-names = "uartclk", "apb_pclk";
>>> +        };
>>> +
>>> +        watchdog@1a420000 {
>>> +            compatible = "arm,sbsa-gwdt";
>>> +            reg = <0x0 0x1a420000 0x0 0x10000>,
>>> +                  <0x0 0x1a430000 0x0 0x10000>;
>>> +            interrupts = <GIC_SPI 50 IRQ_TYPE_LEVEL_HIGH>;
>>> +        };
>>> +
>>> +        rtc@300d0000 {
>>> +            compatible = "arm,pl031", "arm,primecell";
>>> +            reg = <0x0 0x300d0000 0x0 0x10000>;
>>> +            interrupts = <GIC_SPI 268 IRQ_TYPE_LEVEL_HIGH>;
>>
>> Can you please double check this interrupt ID? The IRQ mapping document
>> just lists some "expansion range" here, but I cannot verify if this is
>> using the SPI offset of 32 or not.
>>
> 
> I have confirmed with our interrupt map.
> 
>>> +            clocks = <&soc_clk24mhz>;
>>> +            clock-names = "apb_pclk";
>>> +        };
>>> +
>>> +    };
>>> +
>>> +    psci {
>>> +        compatible = "arm,psci-1.0", "arm,psci-0.2", "arm,psci";
>>
>> You don't need compatibility to the pre 0.2 PSCI standard, so drop the
>> last compatible name.
>>
> 
> I will remove this.
> 
>>> +        method = "smc";
>>> +        cpu_suspend = <0xc4000001>;
>>> +        cpu_off = <0x84000002>;
>>> +        cpu_on = <0xc4000003>;
>>
>> And those three function IDs are only needed for this pre-0.2 name, so 
>> you
>> can remove them.
>>
> 
> I will remove them.
> 
>>> +    };
>>> +
>>> +    sram: sram@104000 {
>>> +        compatible = "mmio-sram";
>>> +        reg = <0x0 0x104000 0x0 0x00001000>;
>>> +        #address-cells = <1>;
>>> +        #size-cells = <1>;
>>> +        ranges = <0 0x0 0x104000 0x00001000>;
>>> +
>>> +        scmi_shmem_tx: scpshmem-sram-section@0 {
>>> +            compatible = "arm,scmi-shmem";
>>> +            reg = <0x0 0x100>;
>>> +        };
>>> +        scmi_shmem_rx: scpshmem-sram-section@100 {
>>> +            compatible = "arm,scmi-shmem";
>>> +            reg = <0x100 0x100>;
>>> +        };
>>> +    };
>>> +
>>> +    mbox_db_tx: mailbox@40020000 {
>>> +        compatible = "arm,mhuv3";
>>> +        reg = <0x0 0x40020000 0x0 0x30000>;
>>> +        clocks = <&soc_clk24mhz>;
>>> +        #mbox-cells = <3>;
>>> +        interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>;
>>> +        interrupt-names = "combined";
>>> +    };
>>> +
>>> +    mbox_db_rx: mailbox@40060000 {
>>> +        compatible = "arm,mhuv3";
>>> +        reg = <0x0 0x40060000 0x0 0x30000>;
>>> +        clocks = <&soc_clk24mhz>;
>>> +        #mbox-cells = <3>;
>>> +        interrupts = <GIC_SPI 113 IRQ_TYPE_LEVEL_HIGH>;
>>> +        interrupt-names = "combined";
>>> +    };
>>> +
>>> +    firmware {
>>> +        scmi {
>>> +            compatible = "arm,scmi";
>>> +            mbox-names = "tx", "rx";
>>> +            mboxes = <&mbox_db_tx 0 0 0 &mbox_db_rx 0 0 0 
>>> &mbox_db_rx 0 0 2>;
>>
>> What is this third mailbox about? I think this would have to match
>> mbox-names also? I guess this is not needed?
>>
> 
> The team is confirming which mbox names are appropriate. To pass the 
> Devicetree validation the only valid combination of three is: "tx", 
> "tx_reply", "rx". However, the second mbox needs to be rx else the SCMI 
> communication fails. I'll investigate further and make sure the names 
> match.

So do you need just one "tx", but "rx" plus "rx_reply"? Which isn't 
valid in the current binding?
If that's the case, then we would need a patch to relax the binding and 
allowing this combination as well.
Looking into the kernel code it looks like the SCMI driver doesn't use 
mbox-names, but explicitly expects assignments depending on the number 
of mboxes? Somewhat confusing ...

Cheers,
Andre

> 
>> Cheers,
>> Andre
>>
>>> +            shmem = <&scmi_shmem_tx &scmi_shmem_rx>;
>>> +            #address-cells = <1>;
>>> +            #size-cells = <0>;
>>> +
>>> +            scmi_dvfs: protocol@13 {
>>> +                reg = <0x13>;
>>> +                #clock-cells = <1>;
>>> +            };
>>> +        };
>>> +    };
>>> +};
>>>
>>
> 
> 

Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Sudeep Holla]

+Cristian(in case I am talking no sense)

On Fri, Jan 30, 2026 at 11:31:25AM +0100, Andre Przywara wrote:
> 
> So do you need just one "tx", but "rx" plus "rx_reply"? Which isn't valid in
> the current binding?
> If that's the case, then we would need a patch to relax the binding and
> allowing this combination as well.
> Looking into the kernel code it looks like the SCMI driver doesn't use
> mbox-names, but explicitly expects assignments depending on the number of
> mboxes? Somewhat confusing ...
> 

It is generally transmitted via tx, and tx_reply is necessary when the
platform has unidirectional channels. tx_reply is used to determine when the
synchronization commands have completed, without requiring polling of the
shared memory. rx_reply is necessary only if the platform firmware expects
it and doesn't poll the shared memory for OSPM/agent acknowledgement.

-- 
Regards,
Sudeep

Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Cristian Marussi]

On Fri, Jan 30, 2026 at 12:34:31PM +0000, Sudeep Holla wrote:
> 
> +Cristian(in case I am talking no sense)
> 
> On Fri, Jan 30, 2026 at 11:31:25AM +0100, Andre Przywara wrote:
> > 
> > So do you need just one "tx", but "rx" plus "rx_reply"? Which isn't valid in
> > the current binding?
> > If that's the case, then we would need a patch to relax the binding and
> > allowing this combination as well.
> > Looking into the kernel code it looks like the SCMI driver doesn't use
> > mbox-names, but explicitly expects assignments depending on the number of
> > mboxes? Somewhat confusing ...

Hi,

so the mbox-names are NOT mandatory, since the SCMI stack initially did
NOT identify mboxes by names and such decision pre-dates me so I am not
sure about the why...

...anyway, when unidirectional mailboxes hw came along, in order to add
clarity, WHILE maintaining backward compatibility, mbox-names were added
only as optional and the stack really does NOT use them; the only thing
that matters is the number and order of mboxes AND shmem areas: only the
combination described in the mboxes binding description are allowed and
accepted in order to manage both the case of unidirectional and
bidirectional mailboxes while surviving backward compatibility.

> > 
> 
> It is generally transmitted via tx, and tx_reply is necessary when the
> platform has unidirectional channels. tx_reply is used to determine when the
> synchronization commands have completed, without requiring polling of the
> shared memory. rx_reply is necessary only if the platform firmware expects
> it and doesn't poll the shared memory for OSPM/agent acknowledgement.

In SCMI you have generally A2P (Agent-to-Platform) bidirectional channels
to send commands and receive related replies using one dedicated shmem and,
optionally, a distinct dedicated unidirectional channel P2A, with a
distinct dedicated shmem, for receiving notifications and/or delayed
responses sent asynchronously by the platform.

These two channels, A2P and P2A, maps in the SCMI stack (for historical
reasons) respectively to TX and RX naming.

If the underlying transport is based on birectional mailboxes you can
happily have 2 mboxes "tx", "rx" with 2 dedicated mbox areas.

Instead if your mailboxes are unidirectional like MHUv3, you will need
effectively 2 mboxes to represent the 2 parts of the A2P birectional
channel AND one mailbox to represent the P2A unidirectional channel,
exactly like you do.

So, if you want to add the optional mbox-names would be:

	firmware {
	    scmi {
	         compatible = "arm,scmi";
		 mbox-names = "tx", "tx_reply", "rx";
		 mboxes = <&mbox_db_tx 0 0 0 &mbox_db_rx 0 0 0 &mbox_db_rx 0 0 2>
                 shmem = <&scmi_shmem_tx &scmi_shmem_rx>;


...since the first 2 mboxes effectively represents the 2 unidirectional
sides of the A2P channel, with first being the cmd-request direction and
the second being the cmd-reply direction, while the third mbox is just the
P2A unidrectional channel...

....so it is fine, even though admittedly fuorviating, that the tx_reply
is attached to a db_rx block, since it is exactly what represents: the
reply to a previously sent command.

Anyway, being the names optional, the only thing that really matters in all
of the above is that the numbers of mboxes and shmems matches:

	 3 mbox / 2 shmem => SCMI TX and RX over 3 mailbox unidirectional channels 

The additional optional rx_reply mboxes was added to represent P2A
channels that have an completion interrupt.

All of this madness was the best way I could find to address the problem
of supporting such new unidirectional mailboxes in the SCMI while NOT
breaking backward compatibility in the absence of mandatory naming from
the start.

Hope to have shed a light, beside having annoyed you all with all of the
above flood of words :P

Thanks,
Cristian

Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Debbie Horsfall]

On 03/02/2026 12:11, Cristian Marussi wrote:
> On Fri, Jan 30, 2026 at 12:34:31PM +0000, Sudeep Holla wrote:
>>
>> +Cristian(in case I am talking no sense)
>>
>> On Fri, Jan 30, 2026 at 11:31:25AM +0100, Andre Przywara wrote:
>>>
>>> So do you need just one "tx", but "rx" plus "rx_reply"? Which isn't valid in
>>> the current binding?
>>> If that's the case, then we would need a patch to relax the binding and
>>> allowing this combination as well.
>>> Looking into the kernel code it looks like the SCMI driver doesn't use
>>> mbox-names, but explicitly expects assignments depending on the number of
>>> mboxes? Somewhat confusing ...
> 
> Hi,
> 
> so the mbox-names are NOT mandatory, since the SCMI stack initially did
> NOT identify mboxes by names and such decision pre-dates me so I am not
> sure about the why...
> 
> ...anyway, when unidirectional mailboxes hw came along, in order to add
> clarity, WHILE maintaining backward compatibility, mbox-names were added
> only as optional and the stack really does NOT use them; the only thing
> that matters is the number and order of mboxes AND shmem areas: only the
> combination described in the mboxes binding description are allowed and
> accepted in order to manage both the case of unidirectional and
> bidirectional mailboxes while surviving backward compatibility.
> 
>>>
>>
>> It is generally transmitted via tx, and tx_reply is necessary when the
>> platform has unidirectional channels. tx_reply is used to determine when the
>> synchronization commands have completed, without requiring polling of the
>> shared memory. rx_reply is necessary only if the platform firmware expects
>> it and doesn't poll the shared memory for OSPM/agent acknowledgement.
> 
> In SCMI you have generally A2P (Agent-to-Platform) bidirectional channels
> to send commands and receive related replies using one dedicated shmem and,
> optionally, a distinct dedicated unidirectional channel P2A, with a
> distinct dedicated shmem, for receiving notifications and/or delayed
> responses sent asynchronously by the platform.
> 
> These two channels, A2P and P2A, maps in the SCMI stack (for historical
> reasons) respectively to TX and RX naming.
> 
> If the underlying transport is based on birectional mailboxes you can
> happily have 2 mboxes "tx", "rx" with 2 dedicated mbox areas.
> 
> Instead if your mailboxes are unidirectional like MHUv3, you will need
> effectively 2 mboxes to represent the 2 parts of the A2P birectional
> channel AND one mailbox to represent the P2A unidirectional channel,
> exactly like you do.
> 
> So, if you want to add the optional mbox-names would be:
> 
> 	firmware {
> 	    scmi {
> 	         compatible = "arm,scmi";
> 		 mbox-names = "tx", "tx_reply", "rx";
> 		 mboxes = <&mbox_db_tx 0 0 0 &mbox_db_rx 0 0 0 &mbox_db_rx 0 0 2>
>                   shmem = <&scmi_shmem_tx &scmi_shmem_rx>;
> 
> 
> ...since the first 2 mboxes effectively represents the 2 unidirectional
> sides of the A2P channel, with first being the cmd-request direction and
> the second being the cmd-reply direction, while the third mbox is just the
> P2A unidrectional channel...
> 
> ....so it is fine, even though admittedly fuorviating, that the tx_reply
> is attached to a db_rx block, since it is exactly what represents: the
> reply to a previously sent command.
> 
> Anyway, being the names optional, the only thing that really matters in all
> of the above is that the numbers of mboxes and shmems matches:
> 
> 	 3 mbox / 2 shmem => SCMI TX and RX over 3 mailbox unidirectional channels
> 
> The additional optional rx_reply mboxes was added to represent P2A
> channels that have an completion interrupt.
> 
> All of this madness was the best way I could find to address the problem
> of supporting such new unidirectional mailboxes in the SCMI while NOT
> breaking backward compatibility in the absence of mandatory naming from
> the start.
> 
> Hope to have shed a light, beside having annoyed you all with all of the
> above flood of words :P
> 
> Thanks,
> Cristian
> 

Hi Cristian,

Thanks very much for the detailed explanation, all makes sense. I will 
add those mbox-names in accordance.

-- 

Kind regards,
Debbie

Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Sudeep Holla]

On Tue, Feb 03, 2026 at 12:11:57PM +0000, Cristian Marussi wrote:
> 
> All of this madness was the best way I could find to address the problem
> of supporting such new unidirectional mailboxes in the SCMI while NOT
> breaking backward compatibility in the absence of mandatory naming from
> the start.
> 

You can attribute this to my expecting an overly ideal scenario with
bidirectional mailbox channels across all platforms using SCMI. At the time, I
did not anticipate the range of configurations that rely on unidirectional
channels.

-- 
Regards,
Sudeep

Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Andre Przywara]

On 2/5/26 12:08, Sudeep Holla wrote:
> On Tue, Feb 03, 2026 at 12:11:57PM +0000, Cristian Marussi wrote:
>>
>> All of this madness was the best way I could find to address the problem
>> of supporting such new unidirectional mailboxes in the SCMI while NOT
>> breaking backward compatibility in the absence of mandatory naming from
>> the start.
>>
> 
> You can attribute this to my expecting an overly ideal scenario with
> bidirectional mailbox channels across all platforms using SCMI. At the time, I
> did not anticipate the range of configurations that rely on unidirectional
> channels.

Would it make sense then to add mbox-names parsing to the code, to 
accommodate new users? There is precedence in some drivers for 
introducing xyz-names for clearer and unambiguous resolution, while 
still falling back to some legacy, fixed associations in case the names 
property doesn't exist.

Cheers,
Andre

Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Sudeep Holla]

On Thu, Feb 05, 2026 at 12:24:58PM +0100, Andre Przywara wrote:
> 
> 
> On 2/5/26 12:08, Sudeep Holla wrote:
> > On Tue, Feb 03, 2026 at 12:11:57PM +0000, Cristian Marussi wrote:
> > > 
> > > All of this madness was the best way I could find to address the problem
> > > of supporting such new unidirectional mailboxes in the SCMI while NOT
> > > breaking backward compatibility in the absence of mandatory naming from
> > > the start.
> > > 
> > 
> > You can attribute this to my expecting an overly ideal scenario with
> > bidirectional mailbox channels across all platforms using SCMI. At the time, I
> > did not anticipate the range of configurations that rely on unidirectional
> > channels.
> 
> Would it make sense then to add mbox-names parsing to the code, to
> accommodate new users? There is precedence in some drivers for introducing
> xyz-names for clearer and unambiguous resolution, while still falling back
> to some legacy, fixed associations in case the names property doesn't exist.
> 

Yes, we can do that; however, my concern is that if RX and TX are swapped, the
names would at least make this apparent. How should we handle shared memory
(shmem), which does not have names? I may be overthinking this the current
logic that checks the number of cells (mboxes and shmem) is likely sufficient,
and we can infer an ordering from that but I would still prefer to avoid
adding unnecessary complexity/mess.

-- 
Regards,
Sudeep

Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Krzysztof Kozlowski]

On 23/01/2026 18:37, Debbie Horsfall wrote:
> Introduce the Zena CSS Fixed Virtual Platform (FVP) dts. This is
> currently the only Zena CSS variant, however the common definitions are
> included in a common dtsi for extensibility.
> 
> Signed-off-by: Debbie Horsfall <debbie.horsfall@arm.com>
> ---
>  MAINTAINERS                              |   1 +
>  arch/arm64/boot/dts/arm/Makefile         |   1 +
>  arch/arm64/boot/dts/arm/zena-css-fvp.dts |  55 ++
>  arch/arm64/boot/dts/arm/zena-css.dtsi    | 826 +++++++++++++++++++++++++++++++
>  4 files changed, 883 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 90d88137adf1..d1d2dae6a71e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3727,6 +3727,7 @@ ARM/ZENA CSS PLATFORM
>  M:	Debbie Horsfall <debbie.horsfall@arm.com>
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/arm/arm,zena-css.yaml
> +F:	arch/arm64/boot/dts/arm/zena-css*

Eeeh, this is getting more and more messier.

All ARM designs or at least all similar like all ARM FVP should have one
group maintainers and that entry now claims "versatile express".

Additional entries for submaintainers is fine, but honestly with this
split of bindings this is getting more and more messier.

I know that ARM is kind of "special" but when it comes to SoCs it should
not be.

Sort out this mess, please, before get accept another platform.

...


> +		cpu-map {
> +

No opening blank lines.

> +			cluster0 {
> +
> +				core0 {
> +					cpu = <&CPU0>;

Labels are lowercase. See DTS coding style.


> +				};
> +
> +				core1 {
> +					cpu = <&CPU1>;
> +				};
> +
> +				core2 {
> +					cpu = <&CPU2>;
> +				};
> +
> +				core3 {
> +					cpu = <&CPU3>;
> +				};
> +			};
> +

...

> +	memory@80000000 {
> +		device_type = "memory";
> +
> +		/* Bank 0: start = 0x0000_0000_8000_0000, size = ~2 GiB (0x7F00_0000) */
> +		reg = <
> +			0x00000000  0x80000000  0x00000000  0x7F000000

Lowercase hex. Also,
> +			0x00000200  0x00000000  0x00000000  0x80000000
> +		>;
> +	};
> +
> +	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>,
> +			<GIC_PPI 12 IRQ_TYPE_LEVEL_LOW>;
> +	};
> +
> +	soc_clk24mhz: clock-24000000 {
> +		compatible = "fixed-clock";
> +		#clock-cells = <0>;
> +		clock-frequency = <24000000>;
> +		clock-output-names = "refclk24mhz";
> +	};
> +
> +	soc: soc {
> +		compatible = "simple-bus";
> +		#address-cells = <2>;
> +		#size-cells = <2>;
> +		ranges;
> +
> +		timer@1a810000 {
> +			compatible = "arm,armv7-timer-mem";
> +			reg = <0x0 0x1a810000 0 0x10000>;
> +			#address-cells = <1>;
> +			#size-cells = <1>;
> +			/* Map child space [0x0..0x30000) to parent @ 0x1a810000 */
> +			ranges = <0x0 0x0 0x1a810000 0x00030000>;
> +
> +			frame@20000 {
> +				frame-number = <0>;
> +				interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
> +				reg = <0x20000 0x10000>;
> +			};
> +		};
> +
> +		gic: interrupt-controller@20800000 {
> +			compatible = "arm,gic-v3";
> +			#redistributor-regions = <16>;
> +			reg = <0x0 0x20800000 0x0 0x10000>,    /* GICD */
> +				<0x0 0x20880000 0x0 0x40000>,    /* 16 * GICR */
> +				<0x0 0x208c0000 0x0 0x40000>,
> +				<0x0 0x20900000 0x0 0x40000>,
> +				<0x0 0x20940000 0x0 0x40000>,
> +				<0x0 0x20980000 0x0 0x40000>,
> +				<0x0 0x209c0000 0x0 0x40000>,
> +				<0x0 0x20a00000 0x0 0x40000>,
> +				<0x0 0x20a40000 0x0 0x40000>,
> +				<0x0 0x20a80000 0x0 0x40000>,
> +				<0x0 0x20ac0000 0x0 0x40000>,
> +				<0x0 0x20b00000 0x0 0x40000>,
> +				<0x0 0x20b40000 0x0 0x40000>,
> +				<0x0 0x20b80000 0x0 0x40000>,
> +				<0x0 0x20bc0000 0x0 0x40000>,
> +				<0x0 0x20c00000 0x0 0x40000>,
> +				<0x0 0x20c40000 0x0 0x40000>;
> +			#interrupt-cells = <3>;
> +			#address-cells = <2>;
> +			#size-cells = <2>;
> +			ranges;
> +			interrupt-controller;
> +			interrupts = <GIC_PPI 9 IRQ_TYPE_LEVEL_HIGH>;
> +
> +			its1: msi-controller@20840000 {
> +				compatible = "arm,gic-v3-its";
> +				reg = <0x0 0x20840000 0x0 0x40000>;
> +				msi-controller;
> +				#msi-cells = <1>;
> +			};
> +		};
> +
> +		/* UART is fixed as 24MHz, both UARTCLK and PCLK */
> +		soc_serial0: serial@1a400000 {

That's some messed ordering. What sort of ordering rule is followed by
ALL ARM SoCs? Not standard DTS coding style? If not, which one and why?

> +			compatible = "arm,pl011", "arm,primecell";
> +			reg = <0x0 0x1a400000 0x0 0x10000>;
> +			interrupts = <GIC_SPI 52 IRQ_TYPE_LEVEL_HIGH>;
> +			clocks = <&soc_clk24mhz>, <&soc_clk24mhz>;
> +			clock-names = "uartclk", "apb_pclk";
> +		};
> +
> +		watchdog@1a420000 {
> +			compatible = "arm,sbsa-gwdt";
> +			reg = <0x0 0x1a420000 0x0 0x10000>,
> +			      <0x0 0x1a430000 0x0 0x10000>;
> +			interrupts = <GIC_SPI 50 IRQ_TYPE_LEVEL_HIGH>;
> +		};
> +
> +		rtc@300d0000 {
> +			compatible = "arm,pl031", "arm,primecell";
> +			reg = <0x0 0x300d0000 0x0 0x10000>;
> +			interrupts = <GIC_SPI 268 IRQ_TYPE_LEVEL_HIGH>;
> +			clocks = <&soc_clk24mhz>;
> +			clock-names = "apb_pclk";
> +		};
> +

No trailing blank lines either. Please clean up your code so it looks
intentional and well organized.


> +	};
> +
> +	psci {
> +		compatible = "arm,psci-1.0", "arm,psci-0.2", "arm,psci";
> +		method = "smc";
> +		cpu_suspend = <0xc4000001>;
> +		cpu_off = <0x84000002>;
> +		cpu_on = <0xc4000003>;
> +	};
> +
> +	sram: sram@104000 {
> +		compatible = "mmio-sram";
> +		reg = <0x0 0x104000 0x0 0x00001000>;
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges = <0 0x0 0x104000 0x00001000>;
> +
> +		scmi_shmem_tx: scpshmem-sram-section@0 {
> +			compatible = "arm,scmi-shmem";
> +			reg = <0x0 0x100>;
> +		};
> +		scmi_shmem_rx: scpshmem-sram-section@100 {
> +			compatible = "arm,scmi-shmem";
> +			reg = <0x100 0x100>;
> +		};
> +	};
> +
> +	mbox_db_tx: mailbox@40020000 {

MMIO nodes are under soc.


Best regards,
Krzysztof

Re: [PATCH 2/2] arm64: dts: zena: Add support for Zena CSS

[Sudeep Holla]

On Thu, Feb 05, 2026 at 01:35:46PM +0100, Krzysztof Kozlowski wrote:
> On 23/01/2026 18:37, Debbie Horsfall wrote:
> > Introduce the Zena CSS Fixed Virtual Platform (FVP) dts. This is
> > currently the only Zena CSS variant, however the common definitions are
> > included in a common dtsi for extensibility.
> > 
> > Signed-off-by: Debbie Horsfall <debbie.horsfall@arm.com>
> > ---
> >  MAINTAINERS                              |   1 +
> >  arch/arm64/boot/dts/arm/Makefile         |   1 +
> >  arch/arm64/boot/dts/arm/zena-css-fvp.dts |  55 ++
> >  arch/arm64/boot/dts/arm/zena-css.dtsi    | 826 +++++++++++++++++++++++++++++++
> >  4 files changed, 883 insertions(+)
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 90d88137adf1..d1d2dae6a71e 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -3727,6 +3727,7 @@ ARM/ZENA CSS PLATFORM
> >  M:	Debbie Horsfall <debbie.horsfall@arm.com>
> >  S:	Maintained
> >  F:	Documentation/devicetree/bindings/arm/arm,zena-css.yaml
> > +F:	arch/arm64/boot/dts/arm/zena-css*
> 
> Eeeh, this is getting more and more messier.
> 
> All ARM designs or at least all similar like all ARM FVP should have one
> group maintainers and that entry now claims "versatile express".
> 

Sorry I saw that you have already pointed towards the above only after
I responded to 1/2. I agree this is not scalable and it is hard to categorise
them at the moment. Hopefully we may get more clarity in sometime in the
near future and we can rework them then. For now, your suggestion sounds
the best approach to take.

> Additional entries for submaintainers is fine, but honestly with this
> split of bindings this is getting more and more messier.
> 
> I know that ARM is kind of "special" but when it comes to SoCs it should
> not be.
> 
> Sort out this mess, please, before get accept another platform.
> 

Noted.

-- 
Regards,
Sudeep