From: Catalin Marinas <catalin.marinas@arm.com>
To: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
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>,
Suzuki K Poulose <Suzuki.Poulose@arm.com>
Subject: Re: [PATCH v4 1/2] firmware: smccc: coco: Manage arm-smccc platform device and CCA auxiliary drivers
Date: Tue, 12 May 2026 15:36:39 +0100 [thread overview]
Message-ID: <agM699d4KwdjnS39@arm.com> (raw)
In-Reply-To: <20260427061615.905018-2-aneesh.kumar@kernel.org>
+ Suzuki
On Mon, Apr 27, 2026 at 11:46:14AM +0530, Aneesh Kumar K.V (Arm) wrote:
> diff --git a/arch/arm64/include/asm/rsi.h b/arch/arm64/include/asm/rsi.h
> index 88b50d660e85..2d2d363aaaee 100644
> --- a/arch/arm64/include/asm/rsi.h
> +++ b/arch/arm64/include/asm/rsi.h
> @@ -10,7 +10,7 @@
> #include <linux/jump_label.h>
> #include <asm/rsi_cmds.h>
>
> -#define RSI_PDEV_NAME "arm-cca-dev"
> +#define RSI_DEV_NAME "arm-rsi-dev"
[...]
> diff --git a/drivers/firmware/smccc/smccc.c b/drivers/firmware/smccc/smccc.c
> index bdee057db2fd..fc9b44b7c687 100644
> --- a/drivers/firmware/smccc/smccc.c
> +++ b/drivers/firmware/smccc/smccc.c
> @@ -12,6 +12,8 @@
> #include <linux/platform_device.h>
> #include <asm/archrandom.h>
>
> +#include "rmm.h"
> +
> static u32 smccc_version = ARM_SMCCC_VERSION_1_0;
> static enum arm_smccc_conduit smccc_conduit = SMCCC_CONDUIT_NONE;
>
> @@ -85,6 +87,18 @@ static int __init smccc_devices_init(void)
> {
> struct platform_device *pdev;
>
> + pdev = platform_device_register_simple("arm-smccc",
> + PLATFORM_DEVID_NONE, NULL, 0);
> + if (IS_ERR(pdev)) {
> + pr_err("arm-smccc: could not register device: %ld\n", PTR_ERR(pdev));
> + } else {
> + /*
> + * Register the RMI and RSI devices only when firmware exposes
> + * the required SMCCC function IDs at a supported revision.
> + */
> + register_rsi_device(pdev);
> + }
So as per the cover letter, instead of "arm-cca-dev" as a platform
device, we get "arm-smccc" as a platform device with an auxiliary
"arm-rsi-dev" child device. This does not get rid of the platform
device, it just creates a synthetic platform device to represent the
SMCCC firmware interface.
Looking at the earlier discussion, I think this is what Greg/Jason were
suggesting, except that we do not currently have an SMCCC platform
device:
https://lore.kernel.org/all/2025101534-frosty-shank-00b1@gregkh/
If we go this route, shouldn't the platform device above be created only
if !SMCCC_CONDUIT_NONE?
"smccc_trng" would also fit this model (together with the driver),
assuming we don't break any user-space (searching the Debian codebase
did not find any use).
--
Catalin
next prev parent reply other threads:[~2026-05-12 14:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-27 6:16 [PATCH v4 0/2] Switch Arm CCA to use an auxiliary device instead of a platform device Aneesh Kumar K.V (Arm)
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)
2026-05-12 14:36 ` Catalin Marinas [this message]
2026-04-27 6:16 ` [PATCH v4 2/2] coco: guest: arm64: Drop dummy RSI platform device stub Aneesh Kumar K.V (Arm)
2026-05-12 14:38 ` Catalin Marinas
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