Re: [PATCH v21 07/13] power: reset: Add psci-reboot-mode driver

Bartosz Golaszewski
2026-04-28T07:56:10Z

On Mon, 27 Apr 2026 19:34:47 +0200, Shivendra Pratap
<shivendra.pratap@oss.qualcomm.com> said:
> PSCI supports different types of resets like SYSTEM_RESET, SYSTEM_RESET2
> ARCH WARM reset and SYSTEM_RESET2 vendor-specific resets. Currently
> there is no common driver that handles all supported psci resets at one
> place. Additionally, there is no common mechanism to issue the supported
> psci resets from userspace.
>
> Add a psci-reboot-mode driver, and define two types of PSCI resets,
> predefined-resets and vendor-specific resets. Predefined-resets are
> defined by psci driver and vendor-specific resets are defined by SoC
> vendors, under the psci:reboot-mode node of SoC device tree.
>
> Register the driver with the reboot-mode framework to interface these
> resets to userspace. When userspace initiates a supported command, pass
> the reset arguments to the PSCI driver to enable command-based reset.
>
> This change allows userspace to issue supported PSCI reset commands
> using the standard reboot system calls while enabling SoC vendors to
> define their specific resets for PSCI.
>
> Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>
> ---
> MAINTAINERS | 1 +
> drivers/power/reset/Kconfig | 10 +++
> drivers/power/reset/Makefile | 1 +
> drivers/power/reset/psci-reboot-mode.c | 109 +++++++++++++++++++++++++++++++++
> 4 files changed, 121 insertions(+)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 333b01fa00b8fbd15e6f31a6b9af47600411624e..8cebc2c7e161c8a226802a4102756b4ed6034395 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21240,6 +21240,7 @@ S: Maintained
> F: Documentation/devicetree/bindings/arm/psci.yaml
> F: drivers/firmware/psci/
> F: drivers/mfd/psci-mfd.c
> +F: drivers/power/reset/psci-reboot-mode.c
> F: include/linux/psci.h
> F: include/uapi/linux/psci.h
>
> diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
> index 124afb99febe92450b6ae322aeed3b63fa2070df..d9d1f768b8691abc3b32f2675519f2ddbaf19b84 100644
> --- a/drivers/power/reset/Kconfig
> +++ b/drivers/power/reset/Kconfig
> @@ -348,6 +348,16 @@ config NVMEM_REBOOT_MODE
> then the bootloader can read it and take different
> action according to the mode.
>
> +config PSCI_REBOOT_MODE
> + bool "PSCI reboot mode driver"
> + depends on OF && ARM_PSCI_FW
> + select REBOOT_MODE
> + help
> + Say y here will enable PSCI reboot mode driver. This gets
> + the PSCI reboot mode arguments and passes them to psci
> + driver. psci driver uses these arguments for issuing
> + device reset into different boot states.
> +
> config POWER_MLXBF
> tristate "Mellanox BlueField power handling driver"
> depends on (GPIO_MLXBF2 || GPIO_MLXBF3) && ACPI
> diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
> index d7ae97241a838fe1b536b2f911868e7590d12e3b..02948622fe3d00e165f941108ab92ecb66b0f0e8 100644
> --- a/drivers/power/reset/Makefile
> +++ b/drivers/power/reset/Makefile
> @@ -40,5 +40,6 @@ obj-$(CONFIG_REBOOT_MODE) += reboot-mode.o
> obj-$(CONFIG_SYSCON_REBOOT_MODE) += syscon-reboot-mode.o
> obj-$(CONFIG_POWER_RESET_SC27XX) += sc27xx-poweroff.o
> obj-$(CONFIG_NVMEM_REBOOT_MODE) += nvmem-reboot-mode.o
> +obj-$(CONFIG_PSCI_REBOOT_MODE) += psci-reboot-mode.o
> obj-$(CONFIG_POWER_MLXBF) += pwr-mlxbf.o
> obj-$(CONFIG_POWER_RESET_QEMU_VIRT_CTRL) += qemu-virt-ctrl.o
> diff --git a/drivers/power/reset/psci-reboot-mode.c b/drivers/power/reset/psci-reboot-mode.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..29f53d2f50da8e34e714adef9507d340bc4130e2
> --- /dev/null
> +++ b/drivers/power/reset/psci-reboot-mode.c
> @@ -0,0 +1,109 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/psci.h>
> +#include <linux/reboot.h>
> +#include <linux/reboot-mode.h>
> +#include <linux/types.h>
> +
> +/* Predefined modes use reset_type = 0 and cookie in magic[63:32]. */
> +#define PSCI_PREDEF_MAGIC(cookie) ((cookie) * BIT_ULL(32))
> +
> +struct psci_predefined_reset {
> + const char *mode;
> + u64 magic;
> +};
> +
> +static const struct psci_predefined_reset psci_resets[] = {
> + {
> + .mode = "psci-system-reset",
> + .magic = PSCI_PREDEF_MAGIC(PSCI_RESET_TYPE_SYSTEM_RESET),
> + },
> + {
> + .mode = "psci-system-reset2-arch-warm-reset",
> + .magic = PSCI_PREDEF_MAGIC(PSCI_RESET_TYPE_SYSTEM_RESET2_ARCH_WARM),
> + },
> +};
> +
> +static int psci_reboot_mode_add_predefined_mode(struct device *dev,
> + struct reboot_mode_driver *reboot,
> + const struct psci_predefined_reset *predef)
> +{
> + struct mode_info *info;
> +
> + info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
> + if (!info)
> + return -ENOMEM;
> +
> + INIT_LIST_HEAD(&info->list);
> + info->mode = predef->mode;
> + info->magic = predef->magic;
> + list_add_tail(&info->list, &reboot->predefined_modes);
> +
> + return 0;
> +}
> +
> +static int psci_reboot_mode_set_predefined_modes(struct device *dev,
> + struct reboot_mode_driver *reboot)
> +{
> + int ret;
> +
> + INIT_LIST_HEAD(&reboot->predefined_modes);
> +
> + /* Always register psci-system-reset. */
> + ret = psci_reboot_mode_add_predefined_mode(dev, reboot, &psci_resets[0]);
> + if (ret)
> + return ret;
> +
> + /* Register arch warm reset only if SYSTEM_RESET2 is supported. */
> + if (!psci_has_system_reset2_support())
> + return 0;
> +
> + return psci_reboot_mode_add_predefined_mode(dev, reboot, &psci_resets[1]);

Looking at this, I'd introduce a core reboot-mode helper for initializing the
predefined_modes field and adding an array of modes and use it here and earlier
in the series.

> +}
> +
> +/*
> + * Pass the encoded magic to psci_set_reset_cmd.
> + * magic is encoded as reset_type (low 32 bits) and cookie (high 32 bits).
> + */
> +static int psci_reboot_mode_write(struct reboot_mode_driver *reboot, u64 magic)
> +{
> + psci_set_reset_cmd(magic);
> + return 0;
> +}
> +
> +static int psci_reboot_mode_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct reboot_mode_driver *reboot;
> + int ret;
> +
> + reboot = devm_kzalloc(dev, sizeof(*reboot), GFP_KERNEL);
> + if (!reboot)
> + return -ENOMEM;
> +
> + ret = psci_reboot_mode_set_predefined_modes(dev, reboot);
> + if (ret)
> + return ret;
> +
> + reboot->write = psci_reboot_mode_write;
> + reboot->dev = dev;
> +
> + return devm_reboot_mode_register(dev, reboot);
> +}
> +
> +static struct platform_driver psci_reboot_mode_driver = {
> + .probe = psci_reboot_mode_probe,
> + .driver = {
> + .name = "psci-reboot-mode",
> + },
> +};
> +
> +module_platform_driver(psci_reboot_mode_driver);
> +
> +MODULE_LICENSE("GPL");
>
> --
> 2.34.1
>
>

Looks good otherwise!

Bart