From: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Lorenzo Pieralisi <lpieralisi@kernel.org>,
Jeremy Linton <jeremy.linton@arm.com>,
Greg KH <gregkh@linuxfoundation.org>,
Mark Rutland <mark.rutland@arm.com>,
Sudeep Holla <sudeep.holla@arm.com>,
Jonathan Cameron <jonathan.cameron@huawei.com>
Subject: [PATCH v3 0/2] Switch Arm CCA to use an auxiliary device from a platform device
Date: Mon, 09 Mar 2026 16:27:49 +0530 [thread overview]
Message-ID: <yq5av7f51d8y.fsf@kernel.org> (raw)
In-Reply-To: <20260309100507.2303361-1-aneesh.kumar@kernel.org>
As discussed here:
https://lore.kernel.org/all/20250728135216.48084-12-aneesh.kumar@kernel.org
The generic feedback was that a platform device should not be used when
there is no underlying platform resource to represent. The existing CCA
support uses a platform device solely to anchor the TSM interface in the
device hierarchy, which is not an appropriate use of a platform device.
Instead, introduce an auxiliary device to track CCA support.
The TSM framework uses the device abstraction to provide cross-architecture
TSM and TEE I/O functionality, including:
Enumerating available platform TEE I/O capabilities
Provisioning connections between the platform TSM and device DSM
For the CCA platform, the resulting device hierarchy appears as follows:
# cd /sys/class/tsm/
# ls -al
total 0
drwxr-xr-x 2 root root 0 Jan 1 00:01 .
drwxr-xr-x 23 root root 0 Jan 1 00:00 ..
lrwxrwxrwx 1 root root 0 Jan 1 00:01 tsm0 -> ../../devices/platform/arm-smccc/arm_cca_host.arm-rmi-dev.0/tsm/tsm0
-aneesh
prev parent reply other threads:[~2026-03-09 10:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-09 10:05 [PATCH v3 1/2] firmware: smccc: coco: Manage arm-smccc platform device and CCA auxiliary drivers Aneesh Kumar K.V (Arm)
2026-03-09 10:05 ` [PATCH v3 2/2] coco: guest: arm64: Drop dummy RSI platform device stub Aneesh Kumar K.V (Arm)
2026-03-09 10:14 ` [PATCH v3 1/2] firmware: smccc: coco: Manage arm-smccc platform device and CCA auxiliary drivers Greg KH
2026-03-09 10:57 ` Aneesh Kumar K.V [this message]
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