Re: [PATCH v3 3/8] dt-bindings: memory-controllers: Add STM32 Octo Memory Manager controller

[Krzysztof Kozlowski]

On Mon, Feb 10, 2025 at 02:18:21PM +0100, patrice.chotard@xxxxxxxxxxx wrote:
> From: Patrice Chotard <patrice.chotard@xxxxxxxxxxx>
> 
> Add bindings for STM32 Octo Memory Manager (OMM) controller.
> 
> OMM manages:
>   - the muxing between 2 OSPI busses and 2 output ports.
>     There are 4 possible muxing configurations:
>       - direct mode (no multiplexing): OSPI1 output is on port 1 and OSPI2
>         output is on port 2
>       - OSPI1 and OSPI2 are multiplexed over the same output port 1
>       - swapped mode (no multiplexing), OSPI1 output is on port 2,
>         OSPI2 output is on port 1
>       - OSPI1 and OSPI2 are multiplexed over the same output port 2
>   - the split of the memory area shared between the 2 OSPI instances.
>   - chip select selection override.
>   - the time between 2 transactions in multiplexed mode.
> 
> Signed-off-by: Patrice Chotard <patrice.chotard@xxxxxxxxxxx>
> ---
>  .../memory-controllers/st,stm32mp25-omm.yaml  | 201 ++++++++++++++++++
>  1 file changed, 201 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/memory-controllers/st,stm32mp25-omm.yaml
> 
> diff --git a/Documentation/devicetree/bindings/memory-controllers/st,stm32mp25-omm.yaml b/Documentation/devicetree/bindings/memory-controllers/st,stm32mp25-omm.yaml
> new file mode 100644
> index 000000000000..c897e6bf490d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/memory-controllers/st,stm32mp25-omm.yaml
> @@ -0,0 +1,201 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/memory-controllers/st,stm32mp25-omm.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: STM32 Octo Memory Manager (OMM)
> +
> +maintainers:
> +  - Patrice Chotard <patrice.chotard@xxxxxxxxxxx>
> +
> +description: |
> +  The STM32 Octo Memory Manager is a low-level interface that enables an
> +  efficient OCTOSPI pin assignment with a full I/O matrix (before alternate
> +  function map) and multiplex of single/dual/quad/octal SPI interfaces over
> +  the same bus. It Supports up to:
> +    - Two single/dual/quad/octal SPI interfaces
> +    - Two ports for pin assignment
> +
> +properties:
> +  compatible:
> +    const: st,stm32mp25-omm
> +
> +  "#address-cells":
> +    const: 2
> +
> +  "#size-cells":
> +    const: 1
> +
> +  ranges:
> +    description: |
> +      Reflects the memory layout with four integer values per OSPI instance.
> +      Format:
> +      <chip-select> 0 <registers base address> <size>
> +    minItems: 2
> +    maxItems: 2
> +
> +  reg:
> +    items:
> +      - description: OMM registers
> +      - description: OMM memory map area
> +
> +  reg-names:
> +    items:
> +      - const: regs
> +      - const: memory_map
> +
> +  memory-region:
> +    description: |
> +      Memory region shared between the 2 OCTOSPI instance.
> +      One or two phandle to a node describing a memory mapped region
> +      depending of child number.
> +    minItems: 1
> +    maxItems: 2
> +
> +  memory-region-names:
> +    description: |
> +      OCTOSPI instance's name to which memory region is associated
> +    items:
> +      enum: [ospi1, ospi2]
> +    minItems: 1
> +    maxItems: 2
> +
> +  clocks:
> +    maxItems: 1
> +
> +  resets:
> +    maxItems: 1
> +
> +  access-controllers:
> +    maxItems: 1
> +
> +  st,syscfg-amcr:
> +    $ref: /schemas/types.yaml#/definitions/phandle-array
> +    description: |
> +      The Address Mapping Control Register (AMCR) is used to split the 256MB
> +      memory map area shared between the 2 OSPI instance. The Octo Memory
> +      Manager sets the AMCR depending of the memory-region configuration.
> +      The memory split bitmask description is:
> +        - 000: OCTOSPI1 (256 Mbytes), OCTOSPI2 unmapped
> +        - 001: OCTOSPI1 (192 Mbytes), OCTOSPI2 (64 Mbytes)
> +        - 010: OCTOSPI1 (128 Mbytes), OCTOSPI2 (128 Mbytes)
> +        - 011: OCTOSPI1 (64 Mbytes), OCTOSPI2 (192 Mbytes)
> +        - 1xx: OCTOSPI1 unmapped, OCTOSPI2 (256 Mbytes)
> +    items:
> +      - description: phandle to syscfg
> +      - description: register offset within syscfg
> +      - description: register bitmask for memory split
> +
> +  st,omm-req2ack-ns:
> +    description: |
> +      In multiplexed mode (MUXEN = 1), this field defines the time in
> +      nanoseconds between two transactions.

default: ?

> +
> +  st,omm-cssel-ovr:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: |
> +      Configure the chip select selector override for the 2 OCTOSPIs.
> +      - 0: OCTOSPI1 chip select send to NCS1 OCTOSPI2 chip select send to NCS1
> +      - 1: OCTOSPI1 chip select send to NCS2 OCTOSPI2 chip select send to NCS1
> +      - 2: OCTOSPI1 chip select send to NCS1 OCTOSPI2 chip select send to NCS2
> +      - 3: OCTOSPI1 chip select send to NCS2 OCTOSPI2 chip select send to NCS2
> +    minimum: 0
> +    maximum: 3

default: ?

> +
> +  st,omm-mux:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: |
> +      Configure the muxing between the 2 OCTOSPIs busses and the 2 output ports.
> +      - 0: direct mode, default

Don't repeat constraints in free form text.

> +      - 1: mux OCTOSPI1 and OCTOSPI2 to port 1
> +      - 2: swapped mode
> +      - 3: mux OCTOSPI1 and OCTOSPI2 to port 2
> +    minimum: 0
> +    maximum: 3

default: ?

None of them are required, so usually we expect defaults.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>

Best regards,
Krzysztof