linux-kernel - Re: [PATCH 3/5] bus: add driver for IMX AIPSTZ bridge

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Message-ID: <a62ab860-5e0e-4ebc-af1f-6fb7ac621e2b@gmail.com>
Date: Mon, 24 Feb 2025 12:07:40 +0200
From: Mihalcea Laurentiu <laurentiumihalcea111@...il.com>
To: Marco Felsch <m.felsch@...gutronix.de>
Cc: Rob Herring <robh@...nel.org>, 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>, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 Pengutronix Kernel Team <kernel@...gutronix.de>, imx@...ts.linux.dev
Subject: Re: [PATCH 3/5] bus: add driver for IMX AIPSTZ bridge


On 24.02.2025 09:55, Marco Felsch wrote:
> Hi Laurentiu,
>
> thanks for your patch.
>
> On 25-02-21, Laurentiu Mihalcea wrote:
>> From: Laurentiu Mihalcea <laurentiu.mihalcea@....com>
>>
>> The secure AHB to IP Slave (AIPSTZ) bus bridge provides access control
>> configurations meant to restrict access to certain peripherals.
>> Some of the configurations include:
>>
>> 	1) Marking masters as trusted for R/W. Based on this
>> 	(and the configuration of the accessed peripheral), the bridge
>> 	may choose to abort the R/W transactions issued by certain
>> 	masters.
> Setting these bits requires very often that the core is running at EL3
> (e.g. secure-monitor) which is not the case for Linux. Can you please
> provide more information how Linux can set these bits?
>
> Regards,
>   Marco


In this particular case, as far as I was able to understand, NS EL1 has enough

privilege to program this IP. This is why Linux can do it.