Subject: Re: [PATCH v4 1/2] firmware: smccc: coco: Manage arm-smccc platform device and CCA auxiliary drivers

From: Catalin Marinas <[email-masked]>
Date: Wed, 13 May 2026 11:47:09 +0100

On Wed, May 13, 2026 at 12:26:13PM +0530, Aneesh Kumar K.V wrote:
> Catalin Marinas <[email-masked]> writes:
> > 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?
> >
> 
> register_rsi_device() does check for 
> 
> 	if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_SMC)
> 		return;

Yes but I meant for the "arm-smccc" platform device, not the rsi one.
You don't want it create if SMCCC_CONDUIT_NONE.

-- 
Catalin