Re: [PATCH v4 1/8] dt-bindings: arm: Add Live Firmware Activation

[Sudeep Holla <sudeep.holla@kernel.org>]

On Fri, Sep 18, 2026 at 04:11:04PM +0200, Andre Przywara wrote:
> The Arm Live Firmware Activation spec [1] describes updating firmware
> images during runtime, without requiring a reboot. Update images might
> be deployed out-of-band, for instance via a BMC, in this case the OS
> needs to be notified about the availability of a new image.
> 
> Describe an interrupt that could be triggered by the platform, to notify
> about any changes.
> 
> [1] https://developer.arm.com/documentation/den0147/latest/
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
> ---
>  .../devicetree/bindings/arm/arm,lfa.yaml      | 50 +++++++++++++++++++
>  1 file changed, 50 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/arm,lfa.yaml
> 
> diff --git a/Documentation/devicetree/bindings/arm/arm,lfa.yaml b/Documentation/devicetree/bindings/arm/arm,lfa.yaml
> new file mode 100644
> index 0000000000000..179c542f383d4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/arm,lfa.yaml
> @@ -0,0 +1,50 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/arm/arm,lfa.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Arm Live Firmware Activation (LFA)
> +
> +maintainers:
> +  - Andre Przywara <andre.przywara@arm.com>
> +  - Sudeep Holla <sudeep.holla@arm.com>
> +
> +description:
> +  The Arm Live Firmware Activation (LFA) specification [1] describes a
> +  firmware interface to activate an updated firmware at runtime, without
> +  requiring a reboot. Updates might be supplied out-of-band, for instance
> +  via a BMC, in which case the platform needs to notify an OS about pending
> +  image updates.
> +  [1] https://developer.arm.com/documentation/den0147/latest/
> +
> +properties:
> +  compatible:
> +    const: arm,lfa
> +
> +  interrupts:
> +    maxItems: 1
> +    description:
> +      The notification interrupt for changed firmware image status. For
> +      an out-of-band firmware update, some system entity would signal
> +      the availability of a firmware update to the host OS via this interrupt.
> +
> +      This must be an edge-triggered IRQ.
> +
> +required:
> +  - compatible
> +  - interrupts
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> +    firmware {
> +        firmware-update {
> +            compatible = "arm,lfa";
> +            interrupts = <GIC_SPI 123 IRQ_TYPE_LEVEL_HIGH>;

Could the example use an edge-triggered interrupt type as it must be
edge-triggered IRQ as per the above scheme ? As written, a device tree
copied from the example violates the binding's requirement.

Alternatively, is the binding incorrect and needs fixing ? I am not sure
if there is any requirement on it from the specification. Where did you
derive it from ?

-- 
Regards,
Sudeep