From: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>
To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Greg KH <gregkh@linuxfoundation.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>
Subject: [PATCH v4 0/2] Switch Arm CCA to use an auxiliary device instead of a platform device
Date: Mon, 27 Apr 2026 11:46:13 +0530 [thread overview]
Message-ID: <20260427061615.905018-1-aneesh.kumar@kernel.org> (raw)
As discussed here:
https://lore.kernel.org/all/20250728135216.48084-12-aneesh.kumar@kernel.org
The general 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.
Use an auxiliary device instead 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 and provisioning connections between the platform TSM and
device DSMs.
For the CCA platform, the resulting device hierarchy appears as follows.
Note that the auxiliary device is still parented by the arm-smccc platform
device, so the sysfs path remains under /devices/platform/arm-smccc/:
$ cd /sys/class/tsm/
$ ls -al
total 0
drwxr-xr-x 2 root root 0 Jan 1 00:02 .
drwxr-xr-x 23 root root 0 Jan 1 00:00 ..
lrwxrwxrwx 1 root root 0 Jan 1 00:03 tsm0 -> ../../devices/platform/arm-smccc/arm_cca_guest.arm-rsi-dev.0/tsm/tsm0
$
Changes from v3:
https://lore.kernel.org/all/20260309100507.2303361-1-aneesh.kumar@kernel.org
* Rebased onto the latest kernel
* Drop pr_fmt() from drivers/firmware/smccc/rmm.c
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Will Deacon <will@kernel.org>
Aneesh Kumar K.V (Arm) (2):
firmware: smccc: coco: Manage arm-smccc platform device and CCA
auxiliary drivers
coco: guest: arm64: Drop dummy RSI platform device stub
arch/arm64/include/asm/rsi.h | 2 +-
arch/arm64/kernel/rsi.c | 15 -----
drivers/firmware/smccc/Kconfig | 1 +
drivers/firmware/smccc/Makefile | 1 +
drivers/firmware/smccc/rmm.c | 23 ++++++++
drivers/firmware/smccc/rmm.h | 17 ++++++
drivers/firmware/smccc/smccc.c | 14 +++++
drivers/virt/coco/arm-cca-guest/Kconfig | 1 +
drivers/virt/coco/arm-cca-guest/Makefile | 2 +
.../{arm-cca-guest.c => arm-cca.c} | 59 +++++++++----------
10 files changed, 89 insertions(+), 46 deletions(-)
create mode 100644 drivers/firmware/smccc/rmm.c
create mode 100644 drivers/firmware/smccc/rmm.h
rename drivers/virt/coco/arm-cca-guest/{arm-cca-guest.c => arm-cca.c} (84%)
--
2.43.0
next reply other threads:[~2026-04-27 6:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-27 6:16 Aneesh Kumar K.V (Arm) [this message]
2026-04-27 6:16 ` [PATCH v4 1/2] firmware: smccc: coco: Manage arm-smccc platform device and CCA auxiliary drivers Aneesh Kumar K.V (Arm)
2026-04-27 6:16 ` [PATCH v4 2/2] coco: guest: arm64: Drop dummy RSI platform device stub Aneesh Kumar K.V (Arm)
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