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From: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Greg KH <gregkh@linuxfoundation.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
	linux-coco@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Jeremy Linton <jeremy.linton@arm.com>,
	Jonathan Cameron <jic23@kernel.org>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Will Deacon <will@kernel.org>,
	Steven Price <steven.price@arm.com>
Subject: Re: [PATCH v5 1/3] firmware: smccc: coco: Manage arm-smccc platform
 device and CCA auxiliary drivers
In-Reply-To: <agXL12bNh4gGyK1K@arm.com>
References: <20260514094030.42495-1-aneesh.kumar@kernel.org>
 <20260514094030.42495-2-aneesh.kumar@kernel.org>
 <0c88bcee-65b5-4328-87e6-e1c714c3d1ca@arm.com>
 <2026051420-amusement-drove-73e6@gregkh> <agXL12bNh4gGyK1K@arm.com>
Date: Thu, 14 May 2026 20:08:01 +0530
Message-ID: <yq5ajyt65a5y.fsf@kernel.org>
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Catalin Marinas <catalin.marinas@arm.com> writes:

> On Thu, May 14, 2026 at 02:55:48PM +0200, Greg Kroah-Hartman wrote:
>> On Thu, May 14, 2026 at 12:04:13PM +0100, Suzuki K Poulose wrote:
>> > On 14/05/2026 10:40, Aneesh Kumar K.V (Arm) wrote:
>> > > Make the SMCCC driver responsible for registering the arm-smccc platform
>> > > device and after confirming the relevant SMCCC function IDs, create
>> > > the arm_cca_guest auxiliary device.
>> > > 
>> > 
>> > There are a few changes squashed in to this patch. Please could we
>> > split the patch in the following order ?
>> > 
>> > 1. Add platform device for arm-smccc
>> 
>> Do not make any more "fake" platform devices please.
>> 
>> > 2. Move TRNG to Auxilliary Device - (Even though it is a later patch, move
>> > it before the RSI changes)
>> 
>> No, move it to the faux api please.
>
> So should we end up with:
>
>   /sys/devices/faux/arm-smccc/
>     smccc_trng/
>     arm-rsi-dev/
>       tsm/tsm0
>
>   /sys/class/tsm/tsm0
>     -> ../../devices/faux/arm-smccc/arm-rsi-dev/tsm/tsm0
>
>   /sys/firmware/cca/
>     realm_guest

But we need the ability to autoload different TSM backend drivers based
on the support/availability of these SMCCC function-id ranges. faux
device don't support that.

-aneesh