dt-bindings: usb: Add binding for Microchip usb5744 hub controller

  The Microchip usb5744 is a SS/HS USB 3.0 hub controller with 4 ports.
The binding describes USB related aspects of the USB5744 hub, it as
well cover the option of connecting the controller as an i2c slave.
When i2c interface is connected hub needs to be initialized first.
Hub itself has fixed i2c address 0x2D but hardcoding address is not good
idea because address can be shifted by i2c address translator in the
middle.

Signed-off-by: Piyush Mehta <piyush.mehta@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
---

It looks like that usb8041 has also an optional i2c interface which is not
covered. But it is mentioned at commit 40e58a8a7ca6 ("dt-bindings: usb:
Add binding for TI USB8041 hub controller").

i2c-bus name property was suggested by Rob at
https://lore.kernel.org/all/CAL_JsqJedhX6typpUKbnzV7CLK6UZVjq3CyG9iY_j5DLPqvVdw@mail.gmail.com/
and
https://lore.kernel.org/all/CAL_JsqJZBbu+UXqUNdZwg-uv0PAsNg55026PTwhKr5wQtxCjVQ@mail.gmail.com/

the question is if adding address like this is acceptable.
But it must be specified.

Driver will follow based on final dt-binding.

---
 .../bindings/usb/microchip,usb5744.yaml       | 85 +++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/usb/microchip,usb5744.yaml
  

On 03/05/2023 15:39, Michal Simek wrote:
> The Microchip usb5744 is a SS/HS USB 3.0 hub controller with 4 ports.
> The binding describes USB related aspects of the USB5744 hub, it as
> well cover the option of connecting the controller as an i2c slave.
> When i2c interface is connected hub needs to be initialized first.
> Hub itself has fixed i2c address 0x2D but hardcoding address is not good
> idea because address can be shifted by i2c address translator in the
> middle.
> 
> Signed-off-by: Piyush Mehta <piyush.mehta@amd.com>
> Signed-off-by: Michal Simek <michal.simek@amd.com>
> ---
> 
> It looks like that usb8041 has also an optional i2c interface which is not
> covered. But it is mentioned at commit 40e58a8a7ca6 ("dt-bindings: usb:
> Add binding for TI USB8041 hub controller").
> 
> i2c-bus name property was suggested by Rob at
> https://lore.kernel.org/all/CAL_JsqJedhX6typpUKbnzV7CLK6UZVjq3CyG9iY_j5DLPqvVdw@mail.gmail.com/
> and
> https://lore.kernel.org/all/CAL_JsqJZBbu+UXqUNdZwg-uv0PAsNg55026PTwhKr5wQtxCjVQ@mail.gmail.com/
> 
> the question is if adding address like this is acceptable.
> But it must be specified.

Why? phandle points it explicitly.

> 
> Driver will follow based on final dt-binding.
> 
> ---
>  .../bindings/usb/microchip,usb5744.yaml       | 85 +++++++++++++++++++
>  1 file changed, 85 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/usb/microchip,usb5744.yaml
> 
> diff --git a/Documentation/devicetree/bindings/usb/microchip,usb5744.yaml b/Documentation/devicetree/bindings/usb/microchip,usb5744.yaml
> new file mode 100644
> index 000000000000..fafe275a35df
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/usb/microchip,usb5744.yaml
> @@ -0,0 +1,85 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/usb/microchip,usb5744.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Microchip USB5744 4-port Hub Controller
> +
> +description:
> +  Microchip's USB5744 SmartHubTM IC is a 4 port, SuperSpeed (SS)/Hi-Speed (HS),
> +  low power, low pin count configurable and fully compliant with the USB 3.1
> +  Gen 1 specification. The USB5744 also supports Full Speed (FS) and Low Speed
> +  (LS) USB signaling, offering complete coverage of all defined USB operating
> +  speeds. The new SuperSpeed hubs operate in parallel with the USB 2.0
> +  controller, so 5 Gbps SuperSpeed data transfers are not affected by slower
> +  USB 2.0 traffic.
> +
> +maintainers:
> +  - Piyush Mehta <piyush.mehta@amd.com>
> +  - Michal Simek <michal.simek@amd.com>
> +
> +allOf:
> +  - $ref: usb-device.yaml#
> +
> +properties:
> +  compatible:
> +    enum:
> +      - usb424,5744
> +      - usb424,2744

Keep the list ordered, so 2744 before 5744.

> +
> +  reg: true
> +
> +  reset-gpios:
> +    maxItems: 1
> +    description:
> +      GPIO controlling the GRST# pin.
> +
> +  vdd-supply:
> +    description:
> +      VDD power supply to the hub
> +
> +  peer-hub:
> +    $ref: /schemas/types.yaml#/definitions/phandle
> +    description:
> +      phandle to the peer hub on the controller.
> +
> +  i2c-bus:
> +    maxItems: 1
> +    description:
> +      phandle of an I2C controller to link usb-hub for usb attach and reset
> +      followed by i2c address.
> +
> +required:
> +  - compatible
> +  - reg
> +  - peer-hub
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    usb {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        /* 2.0 hub on port 1 */
> +        hub_2_0: hub@1 {
> +          compatible = "usb424,5744";

Mixed indentation, use four spaces here as well.

> +          reg = <1>;
> +          peer-hub = <&hub_3_0>;
> +          i2c-bus = <&i2c 0x2d>;
> +          reset-gpios = <&gpio 3 GPIO_ACTIVE_LOW>;
> +        };
Krzysztof
  

On 5/4/23 08:46, Krzysztof Kozlowski wrote:
> On 03/05/2023 15:39, Michal Simek wrote:
>> The Microchip usb5744 is a SS/HS USB 3.0 hub controller with 4 ports.
>> The binding describes USB related aspects of the USB5744 hub, it as
>> well cover the option of connecting the controller as an i2c slave.
>> When i2c interface is connected hub needs to be initialized first.
>> Hub itself has fixed i2c address 0x2D but hardcoding address is not good
>> idea because address can be shifted by i2c address translator in the
>> middle.
>>
>> Signed-off-by: Piyush Mehta <piyush.mehta@amd.com>
>> Signed-off-by: Michal Simek <michal.simek@amd.com>
>> ---
>>
>> It looks like that usb8041 has also an optional i2c interface which is not
>> covered. But it is mentioned at commit 40e58a8a7ca6 ("dt-bindings: usb:
>> Add binding for TI USB8041 hub controller").
>>
>> i2c-bus name property was suggested by Rob at
>> https://lore.kernel.org/all/CAL_JsqJedhX6typpUKbnzV7CLK6UZVjq3CyG9iY_j5DLPqvVdw@mail.gmail.com/
>> and
>> https://lore.kernel.org/all/CAL_JsqJZBbu+UXqUNdZwg-uv0PAsNg55026PTwhKr5wQtxCjVQ@mail.gmail.com/
>>
>> the question is if adding address like this is acceptable.
>> But it must be specified.
> 
> Why? phandle points it explicitly.

Ok it means just list usb hub on i2c with label and point to it. Works for me.

Thanks,
Michal
  

On 04/05/2023 09:25, Michal Simek wrote:
> 
> 
> On 5/4/23 08:46, Krzysztof Kozlowski wrote:
>> On 03/05/2023 15:39, Michal Simek wrote:
>>> The Microchip usb5744 is a SS/HS USB 3.0 hub controller with 4 ports.
>>> The binding describes USB related aspects of the USB5744 hub, it as
>>> well cover the option of connecting the controller as an i2c slave.
>>> When i2c interface is connected hub needs to be initialized first.
>>> Hub itself has fixed i2c address 0x2D but hardcoding address is not good
>>> idea because address can be shifted by i2c address translator in the
>>> middle.
>>>
>>> Signed-off-by: Piyush Mehta <piyush.mehta@amd.com>
>>> Signed-off-by: Michal Simek <michal.simek@amd.com>
>>> ---
>>>
>>> It looks like that usb8041 has also an optional i2c interface which is not
>>> covered. But it is mentioned at commit 40e58a8a7ca6 ("dt-bindings: usb:
>>> Add binding for TI USB8041 hub controller").
>>>
>>> i2c-bus name property was suggested by Rob at
>>> https://lore.kernel.org/all/CAL_JsqJedhX6typpUKbnzV7CLK6UZVjq3CyG9iY_j5DLPqvVdw@mail.gmail.com/
>>> and
>>> https://lore.kernel.org/all/CAL_JsqJZBbu+UXqUNdZwg-uv0PAsNg55026PTwhKr5wQtxCjVQ@mail.gmail.com/
>>>
>>> the question is if adding address like this is acceptable.
>>> But it must be specified.
>>
>> Why? phandle points it explicitly.
> 
> Ok it means just list usb hub on i2c with label and point to it. Works for me.

Right. I missed you want the address of the hub but phandle goes to the
bus. I think listing it on I2C bus (see
arch/arm/boot/dts/vf610-zii-scu4-aib.dts) should work. I think we can
have I2C devices without compatibles.

The problem is that property should have only one definition/type and
i2c-bus is already used in other cases as just "phandle". If we go with
your phandle+address approach, then this should be phandle-array with
items and then we have two different types.

Best regards,
Krzysztof
  

On 5/4/23 09:31, Krzysztof Kozlowski wrote:
> CAUTION: This message has originated from an External Source. Please use proper judgment and caution when opening attachments, clicking links, or responding to this email.
> 
> 
> On 04/05/2023 09:25, Michal Simek wrote:
>>
>>
>> On 5/4/23 08:46, Krzysztof Kozlowski wrote:
>>> On 03/05/2023 15:39, Michal Simek wrote:
>>>> The Microchip usb5744 is a SS/HS USB 3.0 hub controller with 4 ports.
>>>> The binding describes USB related aspects of the USB5744 hub, it as
>>>> well cover the option of connecting the controller as an i2c slave.
>>>> When i2c interface is connected hub needs to be initialized first.
>>>> Hub itself has fixed i2c address 0x2D but hardcoding address is not good
>>>> idea because address can be shifted by i2c address translator in the
>>>> middle.
>>>>
>>>> Signed-off-by: Piyush Mehta <piyush.mehta@amd.com>
>>>> Signed-off-by: Michal Simek <michal.simek@amd.com>
>>>> ---
>>>>
>>>> It looks like that usb8041 has also an optional i2c interface which is not
>>>> covered. But it is mentioned at commit 40e58a8a7ca6 ("dt-bindings: usb:
>>>> Add binding for TI USB8041 hub controller").
>>>>
>>>> i2c-bus name property was suggested by Rob at
>>>> https://lore.kernel.org/all/CAL_JsqJedhX6typpUKbnzV7CLK6UZVjq3CyG9iY_j5DLPqvVdw@mail.gmail.com/
>>>> and
>>>> https://lore.kernel.org/all/CAL_JsqJZBbu+UXqUNdZwg-uv0PAsNg55026PTwhKr5wQtxCjVQ@mail.gmail.com/
>>>>
>>>> the question is if adding address like this is acceptable.
>>>> But it must be specified.
>>>
>>> Why? phandle points it explicitly.
>>
>> Ok it means just list usb hub on i2c with label and point to it. Works for me.
> 
> Right. I missed you want the address of the hub but phandle goes to the
> bus. I think listing it on I2C bus (see
> arch/arm/boot/dts/vf610-zii-scu4-aib.dts) should work. I think we can
> have I2C devices without compatibles.

Device is definitely on i2c bus. But the problem with phande to bus is that 
there could more the same usb hubs and different i2c addresses of it. That's why 
I need to have exact match.
Marek has similar hub where i2c address can be strapped too.

> The problem is that property should have only one definition/type and
> i2c-bus is already used in other cases as just "phandle". If we go with
> your phandle+address approach, then this should be phandle-array with
> items and then we have two different types.

What to do with it then?

Thanks,
Michal
  

On 04/05/2023 09:55, Michal Simek wrote:
> 
> 
> On 5/4/23 09:31, Krzysztof Kozlowski wrote:
>> CAUTION: This message has originated from an External Source. Please use proper judgment and caution when opening attachments, clicking links, or responding to this email.
>>
>>
>> On 04/05/2023 09:25, Michal Simek wrote:
>>>
>>>
>>> On 5/4/23 08:46, Krzysztof Kozlowski wrote:
>>>> On 03/05/2023 15:39, Michal Simek wrote:
>>>>> The Microchip usb5744 is a SS/HS USB 3.0 hub controller with 4 ports.
>>>>> The binding describes USB related aspects of the USB5744 hub, it as
>>>>> well cover the option of connecting the controller as an i2c slave.
>>>>> When i2c interface is connected hub needs to be initialized first.
>>>>> Hub itself has fixed i2c address 0x2D but hardcoding address is not good
>>>>> idea because address can be shifted by i2c address translator in the
>>>>> middle.
>>>>>
>>>>> Signed-off-by: Piyush Mehta <piyush.mehta@amd.com>
>>>>> Signed-off-by: Michal Simek <michal.simek@amd.com>
>>>>> ---
>>>>>
>>>>> It looks like that usb8041 has also an optional i2c interface which is not
>>>>> covered. But it is mentioned at commit 40e58a8a7ca6 ("dt-bindings: usb:
>>>>> Add binding for TI USB8041 hub controller").
>>>>>
>>>>> i2c-bus name property was suggested by Rob at
>>>>> https://lore.kernel.org/all/CAL_JsqJedhX6typpUKbnzV7CLK6UZVjq3CyG9iY_j5DLPqvVdw@mail.gmail.com/
>>>>> and
>>>>> https://lore.kernel.org/all/CAL_JsqJZBbu+UXqUNdZwg-uv0PAsNg55026PTwhKr5wQtxCjVQ@mail.gmail.com/
>>>>>
>>>>> the question is if adding address like this is acceptable.
>>>>> But it must be specified.
>>>>
>>>> Why? phandle points it explicitly.
>>>
>>> Ok it means just list usb hub on i2c with label and point to it. Works for me.
>>
>> Right. I missed you want the address of the hub but phandle goes to the
>> bus. I think listing it on I2C bus (see
>> arch/arm/boot/dts/vf610-zii-scu4-aib.dts) should work. I think we can
>> have I2C devices without compatibles.
> 
> Device is definitely on i2c bus. But the problem with phande to bus is that 
> there could more the same usb hubs and different i2c addresses of it. That's why 
> I need to have exact match.
> Marek has similar hub where i2c address can be strapped too.
> 
>> The problem is that property should have only one definition/type and
>> i2c-bus is already used in other cases as just "phandle". If we go with
>> your phandle+address approach, then this should be phandle-array with
>> items and then we have two different types.
> 
> What to do with it then?

Your idea. I think you missed part of my comment. Add hub to the I2C bus
and phandle to the hub I2C device node.

Best regards,
Krzysztof