linux-kernel - Re: [PATCH v3] dt-bindings: arm: keystone: add boot

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Message-ID: <DEMSLNLDXSNY.2CMMGUMUOYA9T@ti.com>
Date: Mon, 1 Dec 2025 15:32:55 +0530
From: Anshul Dalal <anshuld@...com>
To: Nishanth Menon <nm@...com>, Anshul Dalal <anshuld@...com>
CC: Tero Kristo <kristo@...nel.org>, Santosh Shilimkar <ssantosh@...nel.org>,
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Vignesh
 Raghavendra" <vigneshr@...com>
Subject: Re: [PATCH v3] dt-bindings: arm: keystone: add boot_* mboxes to
 ti,sci

On Wed Nov 12, 2025 at 8:58 PM IST, Nishanth Menon wrote:
> On 15:54-20251112, Anshul Dalal wrote:
>> The bootloader on K3 devices makes use of mailboxes as per the ROM spec
>> which might be different than one's available to the kernel (firmware
>> spec).
>> 
>> Therefore, this patch adds the missing mailbox entries to the DT binding
>> to represent the mailboxes exposed by the hardware during boot for the
>> purpose of loading the firmware.
>> 
>> Signed-off-by: Anshul Dalal <anshuld@...com>
>> ---
>> Changes in v3:
>> - Drop [1/2] of the last patch series
>> - Update existing example with boot_* mailboxes instead of adding a new one
>> - Link to v2: https://lore.kernel.org/r/20251112-k3_syscon_add_boot_mailboxes-v2-0-aebc1e47b391@ti.com
>> 
>> Changes in v2:
>> - Remove maxItems entry
>> - Remove RFC tag from patch (added by mistake in v1)
>> - Document the new mailboxes in mboxes instead of mbox-names
>> - Provide example with all the mailboxes set
>> - Update commit title to have "ti,sci"
>> - Split into two patches
>> - Link to v1: https://lore.kernel.org/r/20251111-k3_syscon_add_boot_mailboxes-v1-1-529a27f21076@ti.com
>> ---
>>  .../devicetree/bindings/arm/keystone/ti,sci.yaml      | 19 ++++++++++++++++---
>>  1 file changed, 16 insertions(+), 3 deletions(-)
>> 
>> diff --git a/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml b/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml
>> index 25a2b42105e541cb3c8ad12a0dfec1af038fa907..be8a5b2b051b441884795059c70892910d981130 100644
>> --- a/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml
>> +++ b/Documentation/devicetree/bindings/arm/keystone/ti,sci.yaml
>> @@ -51,15 +51,27 @@ properties:
>>      minItems: 1
>>  
>>    mbox-names:
>> +    minItems: 2
>>      description: |
>>        Specifies the mailboxes used to communicate with TI-SCI Controller
>>        made available from TI-SCI controller.
>>      items:
>>        - const: rx
>>        - const: tx
>> +      - const: notify
>> +      - const: boot_rx
>> +      - const: boot_tx
>> +      - const: boot_notify
>
> Sorry for joining the party late.. just saw the thread while happening
> to glance at the pending list..
>
> k2g does not use boot_* mboxes, the load mechanism doesn't involve
> ROM talking over mboxes, we load the pmmc on that SoC! ti,am654-sci
> onwards does. This would be a good case for adding a conditional
> property, IMHO. That said majority of the K3 dts entries still use
> k2g-sci for k3 (#facepalm.. i should have caught it, but missed).. but
> that cleanup is for follow on patches that could fix.. driver seems to
> be able to handle the same.
>

Should we therefore have the new mboxes be conditional on "ti,am654-sci"
while k2g continues to use the existing "rx" and "tx" mboxes?

Something similar to:

	if:
	  properties:
	    compatible:
	      contains:
		const: ti,am654-sci
	then:
	  properties:
	    mbox-names:
	      minItems: 2
	      items:
		- const: rx
		- const: tx
		- const: notify
		- const: boot_rx
		- const: boot_tx
		- const: boot_notify
	    mboxes:
	      minItems: 2
	      items:
		- description: RX thread
		- description: TX thread
		- description: Notify thread
		- description: boot stage RX thread
		- description: boot stage TX thread
		- description: boot stage Notify thread
	else:
	  properties:
	    mbox-names:
	      items:
		- const: rx
		- const: tx
	    mboxes:
	      maxItems: 2

With the top level mbox* having a minItems of 2 and max of 6.

Regards,
Anshul

>>  
>>    mboxes:
>>      minItems: 2
>> +    items:
>> +      - description: RX thread
>> +      - description: TX thread
>> +      - description: Notify thread
>> +      - description: boot stage RX thread
>> +      - description: boot stage TX thread
>> +      - description: boot stage Notify thread
>>  
>>    ti,host-id:
>>      $ref: /schemas/types.yaml#/definitions/uint32
>> @@ -90,9 +102,10 @@ examples:
>>    - |
>>      pmmc: system-controller@...1800 {
>>        compatible = "ti,k2g-sci";
>> -      mbox-names = "rx", "tx";
>> -      mboxes = <&msgmgr 5 2>,
>> -               <&msgmgr 0 0>;
>> +      mbox-names = "rx", "tx", "notify", "boot_rx", "boot_tx", "boot_notify";
>> +      mboxes = <&secure_proxy_mcu 8>, <&secure_proxy_mcu 6>,
>> +        <&secure_proxy_mcu 5>, <&secure_proxy_mcu 4>,
>> +        <&secure_proxy_mcu 5>, <&secure_proxy_sa3 5>;
>
>
>>        reg-names = "debug_messages";
>>        reg = <0x02921800 0x800>;
>>      };
>> 
>> ---
>> base-commit: 4427259cc7f7571a157fbc9b5011e1ef6fe0a4a8
>> change-id: 20251105-k3_syscon_add_boot_mailboxes-8452bdd98962
>> 
>> Best regards,
>> -- 
>> Anshul Dalal <anshuld@...com>
>>