Re: [PATCH v4 1/6] dt-bindings: remoteproc: Add Xilinx RPU subsystem bindings

[Rob Herring]

On Wed, Apr 20, 2022 at 12:44:47AM -0700, Tanmay Shah wrote:
> Xilinx ZynqMP platform has dual-core ARM Cortex R5 Realtime Processing
> Unit(RPU) subsystem. This patch adds dt-bindings for RPU subsystem (cluster).
> 
> Signed-off-by: Tanmay Shah <tanmay.shah@xxxxxxxxxx>
> ---
> 
> Changes in v4:
>   - Add memory-region, mboxes and mbox-names properties in example
> 
> Changes in v3:
>   - None
> 
>  .../bindings/remoteproc/xlnx,r5f-rproc.yaml   | 145 ++++++++++++++++++
>  include/dt-bindings/power/xlnx-zynqmp-power.h |   6 +
>  2 files changed, 151 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/remoteproc/xlnx,r5f-rproc.yaml
> 
> diff --git a/Documentation/devicetree/bindings/remoteproc/xlnx,r5f-rproc.yaml b/Documentation/devicetree/bindings/remoteproc/xlnx,r5f-rproc.yaml
> new file mode 100644
> index 000000000000..c1f99e17b4b2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/remoteproc/xlnx,r5f-rproc.yaml
> @@ -0,0 +1,145 @@
> +# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/remoteproc/xlnx,r5f-rproc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Xilinx R5F processor subsystem
> +
> +maintainers:
> +  - Ben Levinsky <ben.levinsky@xxxxxxxxxx>
> +  - Tanmay Shah <tanmay.shah@xxxxxxxxxx>
> +
> +description: |
> +  The Xilinx platforms include a pair of Cortex-R5F processors (RPU) for
> +  real-time processing based on the Cortex-R5F processor core from ARM.
> +  The Cortex-R5F processor implements the Arm v7-R architecture and includes a
> +  floating-point unit that implements the Arm VFPv3 instruction set.
> +
> +properties:
> +  compatible:
> +    const: xlnx,zynqmp-r5fss
> +
> +  xlnx,cluster-mode:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: |
> +      The RPU MPCore can operate in split mode(Dual-processor performance), Safety
> +      lock-step mode(Both RPU cores execute the same code in lock-step,
> +      clock-for-clock) or Single CPU mode (RPU core 0 can be held in reset while
> +      core 1 runs normally). The processor does not support dynamic configuration.
> +      Switching between modes is only permitted immediately after a processor reset.
> +      If set to  1 then lockstep mode and if 0 then split mode.
> +      If set to  2 then single CPU mode. When not defined, default will be lockstep mode.

Constraints of the possible values?

> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 1
> +
> +  reg:
> +    items:
> +      - description: RPU subsystem status and control registers
> +
> +patternProperties:
> +  "^r5f-[a-f0-9]+$":
> +    type: object
> +    description: |
> +      The RPU is located in the Low Power Domain of the Processor Subsystem.
> +      Each processor includes separate L1 instruction and data caches and
> +      tightly coupled memories (TCM). System memory is cacheable, but the TCM
> +      memory space is non-cacheable.
> +
> +      Each RPU contains one 64KB memory and two 32KB memories that
> +      are accessed via the TCM A and B port interfaces, for a total of 128KB
> +      per processor. In lock-step mode, the processor has access to 256KB of
> +      TCM memory.
> +
> +    properties:
> +      compatible:
> +        const: xlnx,zynqmp-r5f
> +
> +      power-domains:
> +        description: |
> +          phandle to a PM domain provider node and an args specifier containing
> +          the r5f0 and r5f1 node id value.

You don't need to redefine what this is, but you need to define how many 
entries and what they are. It sounds like 2 how this is worded, but the 
example shows 1 entry.

> +
> +      reg:
> +        items:
> +          - description: RPU0 and RPU1 control and status registers

1 or 2 entries?

> +
> +      mboxes:
> +        items:
> +          - description: |
> +              Bi-directional channel to send data to RPU and receive ack from RPU.
> +              Request and response message buffers are available and each buffer is 32 bytes.
> +          - description: |
> +              Bi-directional channel to receive data from RPU and send ack from RPU.
> +              Request and response message buffers are available and each buffer is 32 bytes.

I don't think I'd call this bi-directional. Aren't mboxes one direction 
of data flow and the ack is just a detail of the protocol?

> +        minItems: 1
> +
> +      mbox-names:
> +        items:
> +          - const: tx
> +          - const: rx
> +        minItems: 1
> +
> +      sram:
> +        $ref: /schemas/types.yaml#/definitions/phandle-array
> +        minItems: 1
> +        description: |
> +          phandles to one or more reserved on-chip SRAM regions. Other than TCM,
> +          the RPU can execute instructions and access data from, the OCM memory,
> +          the main DDR memory, and other system memories.
> +
> +          The regions should be defined as child nodes of the respective SRAM
> +          node, and should be defined as per the generic bindings in,
> +          Documentation/devicetree/bindings/sram/sram.yaml
> +
> +      memory-region:
> +        $ref: /schemas/types.yaml#/definitions/phandle-array

Already has a type. 

This needs how many and what each one is.

> +        description: |
> +          List of phandles to the reserved memory regions associated with the
> +          remoteproc device. This is variable and describes the memories shared with
> +          the remote processor (e.g. remoteproc firmware and carveouts, rpmsg
> +          vrings, ...). This reserved memory region will be allocated on DDR memory.
> +          See Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt

Don't link to old text bindings.

> +
> +    required:
> +      - compatible
> +      - power-domains

reg should be required or dropped altogether.

> +
> +    unevaluatedProperties: false
> +
> +required:
> +  - compatible
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    r5fss: r5fss@ff9a0000 {
> +        compatible = "xlnx,zynqmp-r5fss";
> +        xlnx,cluster-mode = <1>;
> +
> +        #address-cells = <1>;
> +        #size-cells = <1>;
> +        reg = <0xff9a0000 0x228>;
> +
> +        r5f-0 {
> +            compatible = "xlnx,zynqmp-r5f";
> +            power-domains = <&zynqmp_firmware 0x7>;
> +            memory-region = <&rproc_0_fw_image>, <&rpu0vdev0buffer>, <&rpu0vdev0vring0>, <&rpu0vdev0vring1>;
> +            mboxes = <&ipi_mailbox_rpu0 0>, <&ipi_mailbox_rpu0 1>;
> +            mbox-names = "tx", "rx";
> +        };
> +
> +        r5f-1 {
> +            compatible = "xlnx,zynqmp-r5f";
> +            power-domains = <&zynqmp_firmware 0x8>;
> +            memory-region = <&rproc_1_fw_image>, <&rpu1vdev0buffer>, <&rpu1vdev0vring0>, <&rpu1vdev0vring1>;
> +            mboxes = <&ipi_mailbox_rpu1 0>, <&ipi_mailbox_rpu1 1>;
> +            mbox-names = "tx", "rx";
> +        };
> +    };
> +...
> diff --git a/include/dt-bindings/power/xlnx-zynqmp-power.h b/include/dt-bindings/power/xlnx-zynqmp-power.h
> index 0d9a412fd5e0..618024cbb20d 100644
> --- a/include/dt-bindings/power/xlnx-zynqmp-power.h
> +++ b/include/dt-bindings/power/xlnx-zynqmp-power.h
> @@ -6,6 +6,12 @@
>  #ifndef _DT_BINDINGS_ZYNQMP_POWER_H
>  #define _DT_BINDINGS_ZYNQMP_POWER_H
>  
> +#define		PD_RPU_0	7
> +#define		PD_RPU_1	8
> +#define		PD_R5_0_ATCM	15
> +#define		PD_R5_0_BTCM	16
> +#define		PD_R5_1_ATCM	17
> +#define		PD_R5_1_BTCM	18
>  #define		PD_USB_0	22
>  #define		PD_USB_1	23
>  #define		PD_TTC_0	24
> -- 
> 2.25.1
> 
>