* [PATCH v4 1/2] firmware: smccc: coco: Manage arm-smccc platform device and CCA auxiliary drivers
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 ` 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)
1 sibling, 0 replies; 3+ messages in thread
From: Aneesh Kumar K.V (Arm) @ 2026-04-27 6:16 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel
Cc: Aneesh Kumar K.V (Arm), Catalin Marinas, Greg KH, Jeremy Linton,
Jonathan Cameron, Lorenzo Pieralisi, Mark Rutland, Sudeep Holla,
Will Deacon
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
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 | 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, 90 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 9e846ce4ef9c..8380e5ba88d2 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -161,7 +161,7 @@ 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..2a6187df3285
--- /dev/null
+++ b/drivers/firmware/smccc/rmm.c
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2026 Arm Limited
+ */
+
+#include <linux/auxiliary_bus.h>
+#include "rmm.h"
+
+void __init register_rsi_device(struct platform_device *pdev)
+{
+ unsigned long ret;
+ unsigned long ver_lower, ver_higher;
+
+ if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_SMC)
+ return;
+
+ ret = rsi_request_version(RSI_ABI_VERSION, &ver_lower, &ver_higher);
+ if (ret != RSI_SUCCESS)
+ return;
+
+ __devm_auxiliary_device_create(&pdev->dev,
+ "arm_cca_guest", RSI_DEV_NAME, NULL, 0);
+}
diff --git a/drivers/firmware/smccc/rmm.h b/drivers/firmware/smccc/rmm.h
new file mode 100644
index 000000000000..a47a650d4f51
--- /dev/null
+++ b/drivers/firmware/smccc/rmm.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _SMCCC_RMM_H
+#define _SMCCC_RMM_H
+
+#include <linux/platform_device.h>
+
+#ifdef CONFIG_ARM64
+#include <asm/rsi_cmds.h>
+void __init register_rsi_device(struct platform_device *pdev);
+#else
+
+static void __init register_rsi_device(struct platform_device *pdev)
+{
+
+}
+#endif
+#endif
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);
+ }
+
if (smccc_trng_available) {
pdev = platform_device_register_simple("smccc_trng", -1,
NULL, 0);
diff --git a/drivers/virt/coco/arm-cca-guest/Kconfig b/drivers/virt/coco/arm-cca-guest/Kconfig
index 3f0f013f03f1..a42359a90558 100644
--- a/drivers/virt/coco/arm-cca-guest/Kconfig
+++ b/drivers/virt/coco/arm-cca-guest/Kconfig
@@ -2,6 +2,7 @@ config ARM_CCA_GUEST
tristate "Arm CCA Guest driver"
depends on ARM64
select TSM_REPORTS
+ select AUXILIARY_BUS
help
The driver provides userspace interface to request and
attestation report from the Realm Management Monitor(RMM).
diff --git a/drivers/virt/coco/arm-cca-guest/Makefile b/drivers/virt/coco/arm-cca-guest/Makefile
index 69eeba08e98a..75a120e24fda 100644
--- a/drivers/virt/coco/arm-cca-guest/Makefile
+++ b/drivers/virt/coco/arm-cca-guest/Makefile
@@ -1,2 +1,4 @@
# SPDX-License-Identifier: GPL-2.0-only
obj-$(CONFIG_ARM_CCA_GUEST) += arm-cca-guest.o
+
+arm-cca-guest-y += arm-cca.o
diff --git a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c b/drivers/virt/coco/arm-cca-guest/arm-cca.c
similarity index 84%
rename from drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
rename to drivers/virt/coco/arm-cca-guest/arm-cca.c
index 0c9ea24a200c..7daada072cc0 100644
--- a/drivers/virt/coco/arm-cca-guest/arm-cca-guest.c
+++ b/drivers/virt/coco/arm-cca-guest/arm-cca.c
@@ -3,6 +3,7 @@
* Copyright (C) 2023 ARM Ltd.
*/
+#include <linux/auxiliary_bus.h>
#include <linux/arm-smccc.h>
#include <linux/cc_platform.h>
#include <linux/kernel.h>
@@ -181,52 +182,50 @@ static int arm_cca_report_new(struct tsm_report *report, void *data)
return ret;
}
-static const struct tsm_report_ops arm_cca_tsm_ops = {
+static const struct tsm_report_ops arm_cca_tsm_report_ops = {
.name = KBUILD_MODNAME,
.report_new = arm_cca_report_new,
};
-/**
- * arm_cca_guest_init - Register with the Trusted Security Module (TSM)
- * interface.
- *
- * Return:
- * * %0 - Registered successfully with the TSM interface.
- * * %-ENODEV - The execution context is not an Arm Realm.
- * * %-EBUSY - Already registered.
- */
-static int __init arm_cca_guest_init(void)
+static void unregister_cca_tsm_report(void *data)
+{
+ tsm_report_unregister(&arm_cca_tsm_report_ops);
+}
+
+static int cca_devsec_tsm_probe(struct auxiliary_device *adev,
+ const struct auxiliary_device_id *id)
{
int ret;
if (!is_realm_world())
return -ENODEV;
- ret = tsm_report_register(&arm_cca_tsm_ops, NULL);
- if (ret < 0)
- pr_err("Error %d registering with TSM\n", ret);
+ ret = tsm_report_register(&arm_cca_tsm_report_ops, NULL);
+ if (ret < 0) {
+ dev_err_probe(&adev->dev, ret, "Error registering with TSM\n");
+ return ret;
+ }
- return ret;
-}
-module_init(arm_cca_guest_init);
+ ret = devm_add_action_or_reset(&adev->dev, unregister_cca_tsm_report, NULL);
+ if (ret < 0) {
+ dev_err_probe(&adev->dev, ret, "Error registering devm action\n");
+ return ret;
+ }
-/**
- * arm_cca_guest_exit - unregister with the Trusted Security Module (TSM)
- * interface.
- */
-static void __exit arm_cca_guest_exit(void)
-{
- tsm_report_unregister(&arm_cca_tsm_ops);
+ return 0;
}
-module_exit(arm_cca_guest_exit);
-/* modalias, so userspace can autoload this module when RSI is available */
-static const struct platform_device_id arm_cca_match[] __maybe_unused = {
- { RSI_PDEV_NAME, 0},
- { }
+static const struct auxiliary_device_id cca_devsec_tsm_id_table[] = {
+ { .name = KBUILD_MODNAME "." RSI_DEV_NAME },
+ {}
};
+MODULE_DEVICE_TABLE(auxiliary, cca_devsec_tsm_id_table);
-MODULE_DEVICE_TABLE(platform, arm_cca_match);
+static struct auxiliary_driver cca_devsec_tsm_driver = {
+ .probe = cca_devsec_tsm_probe,
+ .id_table = cca_devsec_tsm_id_table,
+};
+module_auxiliary_driver(cca_devsec_tsm_driver);
MODULE_AUTHOR("Sami Mujawar <sami.mujawar@arm.com>");
MODULE_DESCRIPTION("Arm CCA Guest TSM Driver");
MODULE_LICENSE("GPL");
--
2.43.0
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