Re: [PATCH v25 04/10] firmware: psci: Add support for PSCI auxiliary devices
From: Shivendra Pratap
Date: Thu Sep 17 2026 - 09:06:27 EST
On 9/16/2026 2:59 PM, Bartosz Golaszewski wrote:
On Mon, 14 Sep 2026 16:59:08 +0200, Shivendra Pratap
<shivendra.pratap@xxxxxxxxxxxxxxxx> said:
PSCI has multiple kernel consumers, such as cpuidle-psci-domain.
Currently, both the PSCI core driver and cpuidle-psci-domain bind
directly to the same PSCI node "arm,psci-1.0". Additional consumers, if
introduced, would also need to bind in the same way, leading to multiple
drivers attached to a single device node.
Introduce a PSCI auxiliary-device provider that binds to "arm,psci-1.0"
and registers PSCI child devices on the auxiliary bus. As the first
user, register cpuidle-psci-domain as an auxiliary device.
Update cpuidle-psci-domain to probe as an auxiliary driver and use
the PSCI device node for power-domain traversal.
Suggested-by: Ulf Hansson <ulf.hansson@xxxxxxxxxxxxxxxx>
Suggested-by: Lee Jones <lee@xxxxxxxxxx>
Suggested-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
Signed-off-by: Shivendra Pratap <shivendra.pratap@xxxxxxxxxxxxxxxx>
---
MAINTAINERS | 1 +
drivers/cpuidle/Kconfig.arm | 1 +
drivers/cpuidle/cpuidle-psci-domain.c | 31 +++++++++++++++-----------
drivers/firmware/psci/Kconfig | 14 ++++++++++++
drivers/firmware/psci/Makefile | 1 +
drivers/firmware/psci/psci-devices.c | 41 +++++++++++++++++++++++++++++++++++
6 files changed, 76 insertions(+), 13 deletions(-)
diff --git a/MAINTAINERS b/MAINTAINERS
index 207a6e2db70c..9c0334ee2ed2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21932,6 +21932,7 @@ L: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx (moderated for non-subscribers)
S: Maintained
F: Documentation/devicetree/bindings/arm/psci.yaml
F: drivers/firmware/psci/
+F: drivers/firmware/psci/psci-devices.c
F: include/linux/psci.h
F: include/uapi/linux/psci.h
diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
index b88b01aa5829..f22e18b05053 100644
--- a/drivers/cpuidle/Kconfig.arm
+++ b/drivers/cpuidle/Kconfig.arm
@@ -36,6 +36,7 @@ config ARM_PSCI_CPUIDLE_DOMAIN
bool "PSCI CPU idle Domain"
depends on ARM_PSCI_CPUIDLE
depends on PM_GENERIC_DOMAINS_OF
+ depends on ARM_PSCI_DEVICES
select DT_IDLE_GENPD
default y
help
diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
index b9e4ad7d43a3..0ce6a83f6588 100644
--- a/drivers/cpuidle/cpuidle-psci-domain.c
+++ b/drivers/cpuidle/cpuidle-psci-domain.c
@@ -9,10 +9,11 @@
#define pr_fmt(fmt) "CPUidle PSCI: " fmt
+#include <linux/auxiliary_bus.h>
#include <linux/cpu.h>
#include <linux/device.h>
#include <linux/kernel.h>
-#include <linux/platform_device.h>
+#include <linux/module.h>
#include <linux/pm_domain.h>
#include <linux/pm_runtime.h>
#include <linux/psci.h>
@@ -122,14 +123,10 @@ static void psci_pd_remove(void)
}
}
-static const struct of_device_id psci_of_match[] = {
- { .compatible = "arm,psci-1.0" },
- {}
-};
-
-static int psci_cpuidle_domain_probe(struct platform_device *pdev)
+static int psci_cpuidle_domain_probe(struct auxiliary_device *auxdev,
+ const struct auxiliary_device_id *id)
{
- struct device_node *np = pdev->dev.of_node;
+ struct device_node *np = auxdev->dev.of_node;
bool use_osi = psci_has_osi_support();
int ret = 0, pd_count = 0;
@@ -177,16 +174,24 @@ static int psci_cpuidle_domain_probe(struct platform_device *pdev)
return ret;
}
-static struct platform_driver psci_cpuidle_domain_driver = {
- .probe = psci_cpuidle_domain_probe,
+static const struct auxiliary_device_id psci_cpuidle_domain_id_table[] = {
+ { .name = "arm-psci.psci-cpuidle-domain" },
+ { }
+};
+MODULE_DEVICE_TABLE(auxiliary, psci_cpuidle_domain_id_table);
+
+static struct auxiliary_driver psci_cpuidle_domain_driver = {
+ .probe = psci_cpuidle_domain_probe,
.driver = {
- .name = "psci-cpuidle-domain",
- .of_match_table = psci_of_match,
+ .suppress_bind_attrs = true,
},
+ .id_table = psci_cpuidle_domain_id_table,
};
static int __init psci_idle_init_domains(void)
{
- return platform_driver_register(&psci_cpuidle_domain_driver);
+ return __auxiliary_driver_register(&psci_cpuidle_domain_driver,
+ THIS_MODULE,
+ "psci-cpuidle-domain");
}
core_initcall(psci_idle_init_domains);
diff --git a/drivers/firmware/psci/Kconfig b/drivers/firmware/psci/Kconfig
index 97944168b5e6..68e381f1a618 100644
--- a/drivers/firmware/psci/Kconfig
+++ b/drivers/firmware/psci/Kconfig
@@ -2,6 +2,20 @@
config ARM_PSCI_FW
bool
+config ARM_PSCI_DEVICES
+ bool "PSCI auxiliary device support"
+ depends on ARM_PSCI_FW
+ depends on OF
+ select AUXILIARY_BUS
+ default y
+ help
+ Say Y here to enable auxiliary device support for PSCI.
+
+ This creates auxiliary devices for PSCI functionality implemented
+ outside the core PSCI firmware driver. These devices allow PSCI
+ child drivers to bind through the auxiliary bus while sharing the
+ PSCI firmware device as their parent.
+
config ARM_PSCI_CHECKER
bool "ARM PSCI checker"
depends on ARM_PSCI_FW && HOTPLUG_CPU && CPU_IDLE && !TORTURE_TEST
diff --git a/drivers/firmware/psci/Makefile b/drivers/firmware/psci/Makefile
index 1956b882470f..8e75a0ed6f74 100644
--- a/drivers/firmware/psci/Makefile
+++ b/drivers/firmware/psci/Makefile
@@ -1,4 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
#
obj-$(CONFIG_ARM_PSCI_FW) += psci.o
+obj-$(CONFIG_ARM_PSCI_DEVICES) += psci-devices.o
obj-$(CONFIG_ARM_PSCI_CHECKER) += psci_checker.o
diff --git a/drivers/firmware/psci/psci-devices.c b/drivers/firmware/psci/psci-devices.c
new file mode 100644
index 000000000000..f1eca61e3269
--- /dev/null
+++ b/drivers/firmware/psci/psci-devices.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#include <linux/auxiliary_bus.h>
+#include <linux/init.h>
I think you need module.h not init.h.
Ack.
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+static int arm_psci_probe(struct platform_device *pdev)
+{
+ struct auxiliary_device *auxdev;
+
+ auxdev = __devm_auxiliary_device_create(&pdev->dev, "arm-psci",
+ "psci-cpuidle-domain", NULL, 0);
+ if (!auxdev)
+ return -ENOMEM;
+
+ return 0;
+}
I would prefer you to move the code between the patches a bit. This patch
should already be introducing the full, future-proof infrastructure for
registering multiple auxiliary devices, so maybe add a static table with device
info? Then in patch 10/10 you'd just extend it for reboot modes.
Ack. will update it.
I'd also not add any ifdef guards here and lesses the build-time dependencies.
You can register the device alright, it just won't get probed if the reboot-mode
support is not there.
Ack.
thanks,
Shivendra