[EXT] Re: [PATCH v3 3/4] dt-bindings: irqchip: imx mu work as msi controller

[Krzysztof Kozlowski]

On 25/07/2022 18:29, Frank Li wrote:
> 
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzysztof.kozlowski at linaro.org>
>> Sent: Saturday, July 23, 2022 1:50 PM
>> To: Frank Li <frank.li at nxp.com>; jdmason at kudzu.us; maz at kernel.org;
>> tglx at linutronix.de; robh+dt at kernel.org; krzysztof.kozlowski+dt at linaro.org;
>> shawnguo at kernel.org; s.hauer at pengutronix.de; kw at linux.com;
>> bhelgaas at google.com
>> Cc: kernel at vger.kernel.org; devicetree at vger.kernel.org; linux-arm-
>> kernel at lists.infradead.org; linux-pci at vger.kernel.org; Peng Fan
>> <peng.fan at nxp.com>; Aisheng Dong <aisheng.dong at nxp.com>;
>> kernel at pengutronix.de; festevam at gmail.com; dl-linux-imx <linux-
>> imx at nxp.com>; kishon at ti.com; lorenzo.pieralisi at arm.com;
>> ntb at lists.linux.dev
>> Subject: [EXT] Re: [PATCH v3 3/4] dt-bindings: irqchip: imx mu work as msi
>> controller
>>
>> Caution: EXT Email
>>
>> On 20/07/2022 23:30, Frank Li wrote:
>>> imx mu support generate irq by write a register.
>>> provide msi controller support so other driver
>>> can use it by standard msi interface.
>>
>> Please start sentences with capital letter. Unfortunately I don't
>> understand the sentences. Please describe shortly the hardware.
> 
> [Frank Li]  MU have 4 registers and both side A and B.  If write one of
> Register,  irq will be trigger at the other side. 
> 
> For example,  writle(a side reg1, 0).  Then b side irq will be trigged.



> 
>>
>>
>>>
>>> Signed-off-by: Frank Li <Frank.Li at nxp.com>
>>> ---
>>>  .../interrupt-controller/fsl,mu-msi.yaml      | 88 +++++++++++++++++++
>>>  1 file changed, 88 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/interrupt-
>> controller/fsl,mu-msi.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/interrupt-controller/fsl,mu-
>> msi.yaml b/Documentation/devicetree/bindings/interrupt-controller/fsl,mu-
>> msi.yaml
>>> new file mode 100644
>>> index 0000000000000..e125294243af3
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/interrupt-controller/fsl,mu-
>> msi.yaml
>>> @@ -0,0 +1,88 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id:
>> https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicet
>> ree.org%2Fschemas%2Finterrupt-controller%2Ffsl%2Cmu-
>> msi.yaml%23&data=05%7C01%7CFrank.Li%40nxp.com%7Cfcec12a0731c
>> 454af5c308da6cdc2a0e%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0
>> %7C637941990101591376%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLj
>> AwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%
>> 7C%7C&sdata=9h9nKyvsWaghry1hkpa5aaxVGYpx6xZRTxhN0S4uB50%3
>> D&reserved=0
>>> +$schema:
>> https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicet
>> ree.org%2Fmeta-
>> schemas%2Fcore.yaml%23&data=05%7C01%7CFrank.Li%40nxp.com%7
>> Cfcec12a0731c454af5c308da6cdc2a0e%7C686ea1d3bc2b4c6fa92cd99c5c3016
>> 35%7C0%7C0%7C637941990101591376%7CUnknown%7CTWFpbGZsb3d8eyJ
>> WIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%
>> 7C3000%7C%7C%7C&sdata=wagM3hl8fpJSm%2Bibw6ENl5lNlQ9fVEHzS
>> OlT%2Bjoridg%3D&reserved=0
>>> +
>>> +title: NXP i.MX Messaging Unit (MU) work as msi controller
>>> +
>>> +maintainers:
>>> +  - Frank Li <Frank.Li at nxp.com>
>>> +
>>> +description: |
>>> +  The Messaging Unit module enables two processors within the SoC to
>>> +  communicate and coordinate by passing messages (e.g. data, status
>>> +  and control) through the MU interface. The MU also provides the ability
>>> +  for one processor to signal the other processor using interrupts.
>>> +
>>> +  Because the MU manages the messaging between processors, the MU
>> uses
>>> +  different clocks (from each side of the different peripheral buses).
>>> +  Therefore, the MU must synchronize the accesses from one side to the
>>> +  other. The MU accomplishes synchronization using two sets of matching
>>> +  registers (Processor A-facing, Processor B-facing).
>>> +
>>> +  MU can work as msi interrupt controller to do doorbell
>>> +
>>> +allOf:
>>> +  - $ref: /schemas/interrupt-controller/msi-controller.yaml#
>>> +
>>> +properties:
>>> +  compatible:
>>> +    enum:
>>> +      - fsl,imx6sx-mu-msi
>>> +      - fsl,imx7ulp-mu-msi
>>> +      - fsl,imx8ulp-mu-msi
>>> +      - fsl,imx8ulp-mu-msi-s4
>>> +
>>> +  reg:
>>> +    minItems: 2
>>
>> Not minItems but maxItems in general, but anyway you need to actually
>> list and describe the items (and then skip min/max)
> [Frank Li] 
> 	I am not sure format.  Any example?
> 
> Reg:
>       Items:
>            - description:  a side register
>            - description: b side register

Yes, but then explain what is A and B in bindings description.

Why MU, which sits on A side needs to access other side (B) registers?

>>
>>> +
>>> +  reg-names:
>>> +    items:
>>> +      - const: a
>>> +      - const: b
>>> +
>>> +  interrupts:
>>> +    maxItems: 1
>>> +
>>> +  clocks:
>>> +    maxItems: 1
>>> +
>>> +  power-domains:
>>> +    maxItems: 2
>>
>> and here you correctly use maxItems, so why min in reg? Anyway, instead
>> you need to list and describe the items.
>  
> Does format is similar with reg?

Yes.

> 	
>>
>> Actually I asked you this last time about interrupts, so you ignored
>> that comment.
> 
> Sorry, which one. Is it below one?  
> 
> ---
>> +  interrupts:
>> +    minItems: 1
>> +    maxItems: 2
> 
> Instead describe the items.

Yes.


Best regards,
Krzysztof