[PATCH v26 04/10] firmware: psci: Add support for PSCI auxiliary devices
From: Shivendra Pratap
Date: Mon Sep 28 2026 - 02:10:35 EST
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. Allow the probe to
succeed if at least one auxiliary device is created.
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>
---
drivers/cpuidle/Kconfig.arm | 1 +
drivers/cpuidle/cpuidle-psci-domain.c | 33 ++++++----
drivers/firmware/psci/Kconfig | 14 ++++
drivers/firmware/psci/Makefile | 1 +
drivers/firmware/psci/psci-devices.c | 116 ++++++++++++++++++++++++++++++++++
5 files changed, 151 insertions(+), 14 deletions(-)
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 5722365b943e..199c1494c566 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>
@@ -121,14 +122,10 @@ 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;
@@ -176,16 +173,24 @@ 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);
+arch_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..d23befc490ed
--- /dev/null
+++ b/drivers/firmware/psci/psci-devices.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#include <linux/array_size.h>
+#include <linux/auxiliary_bus.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+struct arm_psci_device_info {
+ const char *name;
+ const char *of_node_name;
+};
+
+static const struct arm_psci_device_info arm_psci_devices[] = {
+ {
+ .name = "psci-cpuidle-domain",
+ },
+};
+
+static void arm_psci_auxiliary_device_release(struct device *dev)
+{
+ struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
+
+ of_node_put(dev->of_node);
+ kfree(auxdev);
+}
+
+static int arm_psci_auxiliary_device_create(struct device *dev,
+ const struct arm_psci_device_info *info)
+{
+ struct auxiliary_device *auxdev;
+ struct device_node *np;
+ int ret;
+
+ auxdev = kzalloc_obj(*auxdev);
+ if (!auxdev)
+ return -ENOMEM;
+
+ if (info->of_node_name)
+ np = of_get_child_by_name(dev->of_node, info->of_node_name);
+ else
+ np = dev->of_node;
+
+ auxdev->id = 0;
+ auxdev->name = info->name;
+ auxdev->dev.parent = dev;
+ auxdev->dev.release = arm_psci_auxiliary_device_release;
+
+ if (np)
+ device_set_node(&auxdev->dev, of_fwnode_handle(of_node_get(np)));
+
+ ret = auxiliary_device_init(auxdev);
+ if (ret) {
+ of_node_put(auxdev->dev.of_node);
+ kfree(auxdev);
+ goto out_put_node;
+ }
+
+ ret = __auxiliary_device_add(auxdev, "arm-psci");
+ if (ret) {
+ auxiliary_device_uninit(auxdev);
+ goto out_put_node;
+ }
+
+ ret = devm_add_action_or_reset(dev, auxiliary_device_destroy, auxdev);
+
+out_put_node:
+ if (info->of_node_name)
+ of_node_put(np);
+
+ return ret;
+}
+
+static int arm_psci_probe(struct platform_device *pdev)
+{
+ const struct arm_psci_device_info *info;
+ int auxdev_count = 0;
+ int i, ret;
+
+ for (i = 0; i < ARRAY_SIZE(arm_psci_devices); i++) {
+ info = &arm_psci_devices[i];
+ ret = arm_psci_auxiliary_device_create(&pdev->dev, info);
+ if (ret)
+ dev_warn(&pdev->dev, "failed to create %s aux device: %d\n",
+ info->name, ret);
+ else
+ auxdev_count++;
+ }
+
+ return auxdev_count ? 0 : -ENODEV;
+}
+
+static const struct of_device_id arm_psci_of_match[] = {
+ { .compatible = "arm,psci-1.0" },
+ { }
+};
+
+static struct platform_driver arm_psci_driver = {
+ .probe = arm_psci_probe,
+ .driver = {
+ .name = "arm-psci",
+ .of_match_table = arm_psci_of_match,
+ .suppress_bind_attrs = true,
+ },
+};
+
+static int __init arm_psci_init(void)
+{
+ return platform_driver_register(&arm_psci_driver);
+}
+arch_initcall(arm_psci_init);
--
2.34.1