[PATCH v2 10/11] dt-bindings: firmware: add arm,ras-ffh

[Ahmed Tiba]

On 26/02/2026 07:03, Himanshu Chauhan wrote:
> On Fri, Feb 20, 2026 at 7:15 PM Ahmed Tiba <ahmed.tiba at arm.com> wrote:
>>
>> Describe the DeviceTree node that exposes the Arm firmware-first handler
>> CPER provider and hook the file into MAINTAINERS so the binding has an
>> owner.
>>
>> Signed-off-by: Ahmed Tiba <ahmed.tiba at arm.com>
>> ---
>>   .../devicetree/bindings/firmware/arm,ras-ffh.yaml  | 71 ++++++++++++++++++++++
>>   MAINTAINERS                                        |  5 ++
>>   2 files changed, 76 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/firmware/arm,ras-ffh.yaml b/Documentation/devicetree/bindings/firmware/arm,ras-ffh.yaml
>> new file mode 100644
>> index 000000000000..eccbaaf45885
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/firmware/arm,ras-ffh.yaml
>> @@ -0,0 +1,71 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/firmware/arm,ras-ffh.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Arm Firmware-First Handler (FFH) CPER provider
> 
> Please don't called it FFH. FFH stands for Fixed Feature Hardware and
> ACPI uses it at multiple places. It is causing confusion.

Agreed. I can drop "ffh" and rename it to "arm,ras-cper".

>> +
>> +maintainers:
>> +  - Ahmed Tiba <ahmed.tiba at arm.com>
>> +
>> +description: |
>> +  Arm Reliability, Availability and Serviceability (RAS) firmware can expose
>> +  a firmware-first handler (FFH) that provides UEFI CPER Generic Error Status
>> +  blocks directly via DeviceTree. The firmware owns the CPER buffer
>> +  and notifies the OS through an interrupt.
>> +
>> +properties:
>> +  compatible:
>> +    const: arm,ras-ffh
>> +
>> +  reg:
>> +    minItems: 1
>> +    items:
>> +      - description:
>> +          CPER Generic Error Status block exposed by firmware
>> +      - description:
>> +          Optional 32- or 64-bit doorbell register used on platforms
>> +          where firmware needs an explicit "ack" handshake before overwriting
>> +          the CPER buffer. Firmware watches bit 0 and expects the OS to set it
>> +          once the current status block has been consumed.
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +    description:
>> +      Interrupt used to signal that a new status record is ready.
>> +
>> +  memory-region:
>> +    $ref: /schemas/types.yaml#/definitions/phandle
>> +    description:
>> +      Optional phandle to the reserved-memory entry that backs the status
>> +      buffer so firmware and the OS use the same carved-out region.
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - interrupts
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>> +
>> +    reserved-memory {
>> +      #address-cells = <2>;
>> +      #size-cells = <2>;
>> +      ras_cper_buffer: cper at fe800000 {
>> +        reg = <0x0 0xfe800000 0x0 0x1000>;
>> +        no-map;
>> +      };
>> +    };
>> +
>> +    error-handler at fe800000 {
>> +      compatible = "arm,ras-ffh";
>> +      reg = <0xfe800000 0x1000>,
>> +            <0xfe810000 0x4>;
>> +      memory-region = <&ras_cper_buffer>;
>> +      interrupts = <GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>;
>> +    };
>> +...
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index b8d8a5c41597..47db7877b485 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -22027,6 +22027,11 @@ M:     Alexandre Bounine <alex.bou9 at gmail.com>
>>   S:     Maintained
>>   F:     drivers/rapidio/
>>
>> +RAS ERROR STATUS
>> +M:     Ahmed Tiba <ahmed.tiba at arm.com>
>> +S:     Maintained
>> +F:     Documentation/devicetree/bindings/firmware/arm,ras-ffh.yaml
>> +
>>   RAS INFRASTRUCTURE
>>   M:     Tony Luck <tony.luck at intel.com>
>>   M:     Borislav Petkov <bp at alien8.de>
>>
>> --
>> 2.43.0
>>
>>