Subject: Re: [PATCH v3 01/24] dt-bindings: iommu: mediatek: Convert IOMMU to DT schema

From: Krzysztof Kozlowski <[email-masked]>
Date: Fri, 2 Oct 2020 13:07:09 +0200

On Wed, Sep 30, 2020 at 03:06:24PM +0800, Yong Wu wrote:
> Convert MediaTek IOMMU to DT schema.
> 
> Signed-off-by: Yong Wu <[email-masked]>
> ---
>  .../bindings/iommu/mediatek,iommu.txt         | 103 ------------
>  .../bindings/iommu/mediatek,iommu.yaml        | 154 ++++++++++++++++++
>  2 files changed, 154 insertions(+), 103 deletions(-)
>  delete mode 100644 Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
>  create mode 100644 Documentation/devicetree/bindings/iommu/mediatek,iommu.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt b/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
> deleted file mode 100644
> index c1ccd8582eb2..000000000000
> --- a/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
> +++ /dev/null
> @@ -1,103 +0,0 @@
> -* Mediatek IOMMU Architecture Implementation
> -
> -  Some Mediatek SOCs contain a Multimedia Memory Management Unit (M4U), and
> -this M4U have two generations of HW architecture. Generation one uses flat
> -pagetable, and only supports 4K size page mapping. Generation two uses the
> -ARM Short-Descriptor translation table format for address translation.
> -
> -  About the M4U Hardware Block Diagram, please check below:
> -
> -              EMI (External Memory Interface)
> -               |
> -              m4u (Multimedia Memory Management Unit)
> -               |
> -          +--------+
> -          |        |
> -      gals0-rx   gals1-rx    (Global Async Local Sync rx)
> -          |        |
> -          |        |
> -      gals0-tx   gals1-tx    (Global Async Local Sync tx)
> -          |        |          Some SoCs may have GALS.
> -          +--------+
> -               |
> -           SMI Common(Smart Multimedia Interface Common)
> -               |
> -       +----------------+-------
> -       |                |
> -       |             gals-rx        There may be GALS in some larbs.
> -       |                |
> -       |                |
> -       |             gals-tx
> -       |                |
> -   SMI larb0        SMI larb1   ... SoCs have several SMI local arbiter(larb).
> -   (display)         (vdec)
> -       |                |
> -       |                |
> - +-----+-----+     +----+----+
> - |     |     |     |    |    |
> - |     |     |...  |    |    |  ... There are different ports in each larb.
> - |     |     |     |    |    |
> -OVL0 RDMA0 WDMA0  MC   PP   VLD
> -
> -  As above, The Multimedia HW will go through SMI and M4U while it
> -access EMI. SMI is a bridge between m4u and the Multimedia HW. It contain
> -smi local arbiter and smi common. It will control whether the Multimedia
> -HW should go though the m4u for translation or bypass it and talk
> -directly with EMI. And also SMI help control the power domain and clocks for
> -each local arbiter.
> -  Normally we specify a local arbiter(larb) for each multimedia HW
> -like display, video decode, and camera. And there are different ports
> -in each larb. Take a example, There are many ports like MC, PP, VLD in the
> -video decode local arbiter, all these ports are according to the video HW.
> -  In some SoCs, there may be a GALS(Global Async Local Sync) module between
> -smi-common and m4u, and additional GALS module between smi-larb and
> -smi-common. GALS can been seen as a "asynchronous fifo" which could help
> -synchronize for the modules in different clock frequency.
> -
> -Required properties:
> -- compatible : must be one of the following string:
> -	"mediatek,mt2701-m4u" for mt2701 which uses generation one m4u HW.
> -	"mediatek,mt2712-m4u" for mt2712 which uses generation two m4u HW.
> -	"mediatek,mt6779-m4u" for mt6779 which uses generation two m4u HW.
> -	"mediatek,mt7623-m4u", "mediatek,mt2701-m4u" for mt7623 which uses
> -						     generation one m4u HW.
> -	"mediatek,mt8173-m4u" for mt8173 which uses generation two m4u HW.
> -	"mediatek,mt8183-m4u" for mt8183 which uses generation two m4u HW.
> -- reg : m4u register base and size.
> -- interrupts : the interrupt of m4u.
> -- clocks : must contain one entry for each clock-names.
> -- clock-names : Only 1 optional clock:
> -  - "bclk": the block clock of m4u.
> -  Here is the list which require this "bclk":
> -  - mt2701, mt2712, mt7623 and mt8173.
> -  Note that m4u use the EMI clock which always has been enabled before kernel
> -  if there is no this "bclk".
> -- mediatek,larbs : List of phandle to the local arbiters in the current Socs.
> -	Refer to bindings/memory-controllers/mediatek,smi-larb.txt. It must sort
> -	according to the local arbiter index, like larb0, larb1, larb2...
> -- iommu-cells : must be 1. This is the mtk_m4u_id according to the HW.
> -	Specifies the mtk_m4u_id as defined in
> -	dt-binding/memory/mt2701-larb-port.h for mt2701, mt7623
> -	dt-binding/memory/mt2712-larb-port.h for mt2712,
> -	dt-binding/memory/mt6779-larb-port.h for mt6779,
> -	dt-binding/memory/mt8173-larb-port.h for mt8173, and
> -	dt-binding/memory/mt8183-larb-port.h for mt8183.
> -
> -Example:
> -	iommu: iommu@10205000 {
> -		compatible = "mediatek,mt8173-m4u";
> -		reg = <0 0x10205000 0 0x1000>;
> -		interrupts = <GIC_SPI 139 IRQ_TYPE_LEVEL_LOW>;
> -		clocks = <&infracfg CLK_INFRA_M4U>;
> -		clock-names = "bclk";
> -		mediatek,larbs = <&larb0 &larb1 &larb2 &larb3 &larb4 &larb5>;
> -		#iommu-cells = <1>;
> -	};
> -
> -Example for a client device:
> -	display {
> -		compatible = "mediatek,mt8173-disp";
> -		iommus = <&iommu M4U_PORT_DISP_OVL0>,
> -			 <&iommu M4U_PORT_DISP_RDMA0>;
> -		...
> -	};
> diff --git a/Documentation/devicetree/bindings/iommu/mediatek,iommu.yaml b/Documentation/devicetree/bindings/iommu/mediatek,iommu.yaml
> new file mode 100644
> index 000000000000..eae773ad53a3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iommu/mediatek,iommu.yaml
> @@ -0,0 +1,154 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iommu/mediatek,iommu.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MediaTek IOMMU Architecture Implementation
> +
> +maintainers:
> +  - Yong Wu <[email-masked]>
> +
> +description: |+
> +  Some MediaTek SOCs contain a Multimedia Memory Management Unit (M4U), and
> +  this M4U have two generations of HW architecture. Generation one uses flat
> +  pagetable, and only supports 4K size page mapping. Generation two uses the
> +  ARM Short-Descriptor translation table format for address translation.
> +
> +  About the M4U Hardware Block Diagram, please check below:
> +
> +                EMI (External Memory Interface)
> +                 |
> +                m4u (Multimedia Memory Management Unit)
> +                 |
> +            +--------+
> +            |        |
> +        gals0-rx   gals1-rx    (Global Async Local Sync rx)
> +            |        |
> +            |        |
> +        gals0-tx   gals1-tx    (Global Async Local Sync tx)
> +            |        |          Some SoCs may have GALS.
> +            +--------+
> +                 |
> +             SMI Common(Smart Multimedia Interface Common)
> +                 |
> +         +----------------+-------
> +         |                |
> +         |             gals-rx        There may be GALS in some larbs.
> +         |                |
> +         |                |
> +         |             gals-tx
> +         |                |
> +     SMI larb0        SMI larb1   ... SoCs have several SMI local arbiter(larb).
> +     (display)         (vdec)
> +         |                |
> +         |                |
> +   +-----+-----+     +----+----+
> +   |     |     |     |    |    |
> +   |     |     |...  |    |    |  ... There are different ports in each larb.
> +   |     |     |     |    |    |
> +  OVL0 RDMA0 WDMA0  MC   PP   VLD
> +
> +  As above, The Multimedia HW will go through SMI and M4U while it
> +  access EMI. SMI is a bridge between m4u and the Multimedia HW. It contain
> +  smi local arbiter and smi common. It will control whether the Multimedia
> +  HW should go though the m4u for translation or bypass it and talk
> +  directly with EMI. And also SMI help control the power domain and clocks for
> +  each local arbiter.
> +
> +  Normally we specify a local arbiter(larb) for each multimedia HW
> +  like display, video decode, and camera. And there are different ports
> +  in each larb. Take a example, There are many ports like MC, PP, VLD in the
> +  video decode local arbiter, all these ports are according to the video HW.
> +
> +  In some SoCs, there may be a GALS(Global Async Local Sync) module between
> +  smi-common and m4u, and additional GALS module between smi-larb and
> +  smi-common. GALS can been seen as a "asynchronous fifo" which could help
> +  synchronize for the modules in different clock frequency.
> +
> +properties:
> +  compatible:
> +    oneOf:
> +      - enum:
> +          - mediatek,mt2701-m4u # mt2701 generation one HW
> +          - mediatek,mt2712-m4u # mt2712 generation two HW
> +          - mediatek,mt6779-m4u # mt6779 generation two HW
> +          - mediatek,mt8173-m4u # mt8173 generation two HW
> +          - mediatek,mt8183-m4u # mt8183 generation two HW
> +
> +      - description: mt7623 generation one HW
> +        items:
> +          - const: mediatek,mt7623-m4u
> +          - const: mediatek,mt2701-m4u
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  clocks:
> +    description: |
> +      bclk is optional. here is the list which require this bclk:
> +      mt2701, mt2712, mt7623 and mt8173.

Similarly to my comment in other patch, this should be part of schema
within 'if-then'.

Best regards,
Krzysztof

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