Re: [PATCH v3 1/2] firmware: smccc: coco: Manage arm-smccc platform device and CCA auxiliary drivers

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Mar 09, 2026 at 03:35:06PM +0530, 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.
> 
> Also update the arm-cca-guest driver to use the auxiliary device
> interface instead of the platform device (arm-cca-dev). The removal of
> the platform device registration will follow in a subsequent patch,
> allowing this change to be applied without immediately breaking existing
> userspace dependencies [1].
> 
> [1] https://lore.kernel.org/all/4a7d84b2-2ec4-4773-a2d5-7b63d5c683cf@arm.com
> 
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
> Cc: Jeremy Linton <jeremy.linton@arm.com>
> Cc: Greg KH <gregkh@linuxfoundation.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
> Cc: Sudeep Holla <sudeep.holla@arm.com>
> Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
> ---
>  arch/arm64/include/asm/rsi.h                  |  2 +-
>  arch/arm64/kernel/rsi.c                       |  2 +-
>  drivers/firmware/smccc/Kconfig                |  1 +
>  drivers/firmware/smccc/Makefile               |  1 +
>  drivers/firmware/smccc/rmm.c                  | 25 ++++++++
>  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, 92 insertions(+), 32 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%)
> 
> 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"
>  
>  DECLARE_STATIC_KEY_FALSE(rsi_present);
>  
> diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
> index c64a06f58c0b..5d711942e543 100644
> --- a/arch/arm64/kernel/rsi.c
> +++ b/arch/arm64/kernel/rsi.c
> @@ -160,7 +160,7 @@ void __init arm64_rsi_init(void)
>  }
>  
>  static struct platform_device rsi_dev = {
> -	.name = RSI_PDEV_NAME,
> +	.name = "arm-cca-dev",
>  	.id = PLATFORM_DEVID_NONE
>  };
>  
> diff --git a/drivers/firmware/smccc/Kconfig b/drivers/firmware/smccc/Kconfig
> index 15e7466179a6..2b6984757241 100644
> --- a/drivers/firmware/smccc/Kconfig
> +++ b/drivers/firmware/smccc/Kconfig
> @@ -8,6 +8,7 @@ config HAVE_ARM_SMCCC
>  config HAVE_ARM_SMCCC_DISCOVERY
>  	bool
>  	depends on ARM_PSCI_FW
> +	select AUXILIARY_BUS
>  	default y
>  	help
>  	 SMCCC v1.0 lacked discoverability and hence PSCI v1.0 was updated
> diff --git a/drivers/firmware/smccc/Makefile b/drivers/firmware/smccc/Makefile
> index 40d19144a860..146dc3c03c20 100644
> --- a/drivers/firmware/smccc/Makefile
> +++ b/drivers/firmware/smccc/Makefile
> @@ -2,3 +2,4 @@
>  #
>  obj-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY)	+= smccc.o kvm_guest.o
>  obj-$(CONFIG_ARM_SMCCC_SOC_ID)	+= soc_id.o
> +obj-$(CONFIG_ARM64) += rmm.o
> diff --git a/drivers/firmware/smccc/rmm.c b/drivers/firmware/smccc/rmm.c
> new file mode 100644
> index 000000000000..03496330630f
> --- /dev/null
> +++ b/drivers/firmware/smccc/rmm.c
> @@ -0,0 +1,25 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2026 Arm Limited
> + */
> +
> +#define pr_fmt(fmt) "smccc: " fmt

No need for this define as you never use it in this file.

thanks,

greg k-h