Message-ID: <2301b0f7-1a76-4823-8d3f-d346f8f8e865@gmail.com>
Date: Fri, 28 Mar 2025 14:34:11 +0200
From: Mihalcea Laurentiu <laurentiumihalcea111@...il.com>
To: Rob Herring <robh@...nel.org>
Cc: Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
 Sascha Hauer <s.hauer@...gutronix.de>, Fabio Estevam <festevam@...il.com>,
 Daniel Baluta <daniel.baluta@....com>, Shengjiu Wang
 <shengjiu.wang@....com>, Frank Li <Frank.li@....com>,
 Marco Felsch <m.felsch@...gutronix.de>,
 Marc Kleine-Budde <mkl@...gutronix.de>,
 Pengutronix Kernel Team <kernel@...gutronix.de>, devicetree@...r.kernel.org,
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/5] dt-bindings: bus: add documentation for the IMX
 AIPSTZ bridge


On 25.03.2025 05:23, Rob Herring wrote:
> On Mon, Mar 24, 2025 at 12:25:52PM -0400, Laurentiu Mihalcea wrote:
>> From: Laurentiu Mihalcea <laurentiu.mihalcea@....com>
>>
>> Add documentation for IMX AIPSTZ bridge.
>>
>> Co-developed-by: Daniel Baluta <daniel.baluta@....com>
>> Signed-off-by: Daniel Baluta <daniel.baluta@....com>
>> Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@....com>
>> ---
>>  .../bindings/bus/fsl,imx8mp-aipstz.yaml       | 107 ++++++++++++++++++
>>  1 file changed, 107 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/bus/fsl,imx8mp-aipstz.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/bus/fsl,imx8mp-aipstz.yaml b/Documentation/devicetree/bindings/bus/fsl,imx8mp-aipstz.yaml
>> new file mode 100644
>> index 000000000000..c0427dfcdaca
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/bus/fsl,imx8mp-aipstz.yaml
>> @@ -0,0 +1,107 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/bus/fsl,imx8mp-aipstz.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Secure AHB to IP Slave bus (AIPSTZ) bridge
>> +
>> +description:
>> +  The secure AIPS bridge (AIPSTZ) acts as a bridge for AHB masters
>> +  issuing transactions to IP Slave peripherals. Additionally, this module
>> +  offers access control configurations meant to restrict which peripherals
>> +  a master can access.
> Wrap at 80 chars.


fix in v4, thx


>
>> +
>> +maintainers:
>> +  - Laurentiu Mihalcea <laurentiu.mihalcea@....com>
>> +
>> +properties:
>> +  compatible:
>> +    const: fsl,imx8mp-aipstz
>> +
>> +  reg:
>> +    maxItems: 2
>> +
>> +  reg-names:
>> +    items:
>> +      - const: bus
>> +      - const: ac
>> +
>> +  power-domains:
>> +    maxItems: 1
>> +
>> +  "#address-cells":
>> +    const: 1
>> +
>> +  "#size-cells":
>> +    const: 1
>> +
>> +  "#access-controller-cells":
>> +    const: 0
> With 0 cells, how do you identify which device it is?


we don't atm. We're relying on the default configuration.


we don't have any APIs for AC configuration so I left the

cell number to 0 thinking that the cell number might depend

on the API.


if need be, I can set it to the value I was initially thinking of in v4.


>
>> +
>> +  ranges: true
>> +
>> +# borrowed from simple-bus.yaml, no additional requirements for children
>> +patternProperties:
>> +  "@(0|[1-9a-f][0-9a-f]*)$":
>> +    type: object
>> +    additionalProperties: true
>> +    properties:
>> +      reg:
>> +        items:
>> +          minItems: 2
>> +          maxItems: 4
>> +        minItems: 1
>> +        maxItems: 1024
>> +      ranges:
>> +        oneOf:
>> +          - items:
>> +              minItems: 3
>> +              maxItems: 7
>> +            minItems: 1
>> +            maxItems: 1024
>> +          - $ref: /schemas/types.yaml#/definitions/flag
>> +    anyOf:
>> +      - required:
>> +          - reg
>> +      - required:
>> +          - ranges
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - reg-names
>> +  - power-domains
>> +  - "#address-cells"
>> +  - "#size-cells"
>> +  - "#access-controller-cells"
>> +  - ranges
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/clock/imx8mp-clock.h>
>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>> +
>> +    bus@...00000 {
>> +        compatible = "fsl,imx8mp-aipstz";
>> +        reg = <0x30c00000 0x400000>, <0x30df0000 0x10000>;
> It doesn't look like you have any registers in the 1st entry, but they 
> are child devices? Then you should use ranges and drop it here:
>
> ranges = <0x0 0x30c00000 0x400000>;


I guess this would mean switching from global addresses (current way) to

bus-relative addresses for the child devices. This wasn't my intent.


I wonder if we could just switch to V2 in which we just use the bridge's AC

configuration space and an empty 'ranges':


aips5: bus@...f0000 {

    compatible = "fsl,imx8mp-aipstz";

    reg = <0x30df0000 0x10000>;

    /* some more properties here */

    ranges;

};


or as Marco just suggested use


ranges = <0x30c00000 0x30c00000 0x400000>;


instead of an empty 'ranges' to restrict the bus size.


Personally, I'm fine with both approaches but what's your opinion on this?


>
>
>> +        reg-names = "bus", "ac";
>> +        power-domains = <&pgc_audio>;
>> +        #address-cells = <1>;
>> +        #size-cells = <1>;
>> +        #access-controller-cells = <0>;
>> +        ranges;
>> +
>> +        dma-controller@...00000 {
>> +            compatible = "fsl,imx8mp-sdma", "fsl,imx8mq-sdma";
>> +            reg = <0x30e00000 0x10000>;
>> +            #dma-cells = <3>;
>> +            clocks = <&audio_blk_ctrl IMX8MP_CLK_AUDIOMIX_SDMA3_ROOT>,
>> +                     <&clk IMX8MP_CLK_AUDIO_ROOT>;
>> +            clock-names = "ipg", "ahb";
>> +            interrupts = <GIC_SPI 34 IRQ_TYPE_LEVEL_HIGH>;
>> +            fsl,sdma-ram-script-name = "imx/sdma/sdma-imx7d.bin";
> No 'access-controllers' here?


no need for that unless the child wants to request a specific AC

configuration for itself.


>
>> +        };
>> +    };
>> -- 
>> 2.34.1
>>

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