[PATCH v24 04/12] mfd: psci-mfd: Add PSCI MFD driver for cpuidle-psci-domain cell
Lee Jones
lee at kernel.org
Thu Aug 13 05:38:41 PDT 2026
On Mon, 03 Aug 2026, Shivendra Pratap wrote:
> 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 several
> drivers attached to a single device node.
>
> Introduce a PSCI MFD driver that binds to "arm,psci-1.0" and registers
> PSCI child cells. As the first user, register cpuidle-psci-domain as a
> child cell.
>
> Update cpuidle-psci-domain to probe as an MFD child and use the parent
> PSCI node for power-domain traversal.
>
> Suggested-by: Bartosz Golaszewski <bartosz.golaszewski at oss.qualcomm.com>
> Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski at oss.qualcomm.com>
> Signed-off-by: Shivendra Pratap <shivendra.pratap at oss.qualcomm.com>
> ---
> MAINTAINERS | 1 +
> drivers/cpuidle/Kconfig.arm | 1 +
> drivers/cpuidle/cpuidle-psci-domain.c | 9 +-------
> drivers/mfd/Kconfig | 12 ++++++++++
> drivers/mfd/Makefile | 2 ++
> drivers/mfd/psci-mfd.c | 43 +++++++++++++++++++++++++++++++++++
We don't usually allow the use of the term MFD in devices.
What does this do? Is it a mux? psci-mux?
If not, think about what it is and call it that instead.
> 6 files changed, 60 insertions(+), 8 deletions(-)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index fe67f7bfa44c..0b6e4f89f319 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21671,6 +21671,7 @@ L: linux-arm-kernel at lists.infradead.org (moderated for non-subscribers)
> S: Maintained
> F: Documentation/devicetree/bindings/arm/psci.yaml
> F: drivers/firmware/psci/
> +F: drivers/mfd/psci-mfd.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..c5ecca0d7397 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 MFD_PSCI
> 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..a2d01810f295 100644
> --- a/drivers/cpuidle/cpuidle-psci-domain.c
> +++ b/drivers/cpuidle/cpuidle-psci-domain.c
> @@ -17,7 +17,6 @@
> #include <linux/pm_runtime.h>
> #include <linux/psci.h>
> #include <linux/slab.h>
> -#include <linux/string.h>
>
> #include "cpuidle-psci.h"
> #include "dt_idle_genpd.h"
> @@ -122,14 +121,9 @@ 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)
> {
> - struct device_node *np = pdev->dev.of_node;
> + struct device_node *np = pdev->dev.parent->of_node;
dev_of_node(pdev->dev.parent);
> bool use_osi = psci_has_osi_support();
> int ret = 0, pd_count = 0;
>
> @@ -181,7 +175,6 @@ static struct platform_driver psci_cpuidle_domain_driver = {
> .probe = psci_cpuidle_domain_probe,
> .driver = {
> .name = "psci-cpuidle-domain",
> - .of_match_table = psci_of_match,
> },
> };
>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index e4fd4572472f..d18655d76172 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -2374,6 +2374,18 @@ config MFD_KHADAS_MCU
> additional drivers must be enabled in order to use the functionality
> of the device.
>
> +config MFD_PSCI
> + bool "PSCI MFD for psci child cells"
"PSCI mux for registering PSCI component devices" ?
> + depends on ARM_PSCI_FW
> + depends on OF
> + select MFD_CORE
> + default y
> + help
> + PSCI MFD registers PSCI child cells and exposes them as
> + platform devices.
This is what all DT related MFD devices do.
> + Child drivers are probed only if enabled in the
> + kernel configuration.
Nothing new here either. This is the norm.
"PSCI Mux is a Linux specific device splitter designed to register
multiple PSCI related components via a single Device Tree compatible.
Without it, devices would each bind to a single node ... <which causes
problems with x, y and z>"
> + Select this option whenever a supported PSCI
> + child driver is selected.
> +
> config MFD_ACER_A500_EC
> tristate "Support for Acer Iconia Tab A500 Embedded Controller"
> depends on I2C
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 72d3944b0ad8..f3edfad702ff 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -24,6 +24,8 @@ obj-$(CONFIG_MFD_EXYNOS_LPASS) += exynos-lpass.o
> obj-$(CONFIG_MFD_GATEWORKS_GSC) += gateworks-gsc.o
> obj-$(CONFIG_MFD_MACSMC) += macsmc.o
>
> +obj-$(CONFIG_MFD_PSCI) += psci-mfd.o
> +
> obj-$(CONFIG_MFD_TI_LP873X) += lp873x.o
> obj-$(CONFIG_MFD_TI_LP87565) += lp87565.o
> obj-$(CONFIG_MFD_TI_AM335X_TSCADC) += ti_am335x_tscadc.o
> diff --git a/drivers/mfd/psci-mfd.c b/drivers/mfd/psci-mfd.c
> new file mode 100644
> index 000000000000..7affd6bb09dd
> --- /dev/null
> +++ b/drivers/mfd/psci-mfd.c
> @@ -0,0 +1,43 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> + */
> +
> +#include <linux/mfd/core.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +
> +static const struct mfd_cell psci_cells[] = {
> + {
> + .name = "psci-cpuidle-domain",
> + },
> +};
MFD_CELL_NAME() ?
MFD drivers have to support more than one device from the get-go.
Please add your other device here in this patch.
> +static int psci_mfd_probe(struct platform_device *pdev)
No to _mfd_.
> +{
> + return devm_mfd_add_devices(&pdev->dev, PLATFORM_DEVID_AUTO, psci_cells,
> + ARRAY_SIZE(psci_cells), NULL, 0, NULL);
> +}
> +
> +static const struct of_device_id psci_mfd_of_match[] = {
> + { .compatible = "arm,psci-1.0" },
> + { }
> +};
> +
> +static struct platform_driver psci_mfd_driver = {
> + .probe = psci_mfd_probe,
> + .driver = {
> + .name = "psci-mfd",
> + .of_match_table = psci_mfd_of_match,
> + },
> +};
> +
> +static int __init psci_mfd_init(void)
> +{
> + return platform_driver_register(&psci_mfd_driver);
> +}
> +
Remove this line.
> +core_initcall(psci_mfd_init);
This is usually a hack. Why can't you use -EPROBE_DEFER?
> +
> +MODULE_LICENSE("GPL");
>
> --
> 2.34.1
>
--
Lee Jones
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