Re: [PATCH v17 03/12] power: reset: reboot-mode: Add support for 64 bit magic

Mukesh Ojha
2025-11-10T13:45:57Z

On Sun, Nov 09, 2025 at 08:07:16PM +0530, Shivendra Pratap wrote:
> Current reboot-mode supports a single 32-bit argument for any
> supported mode. Some reboot-mode based drivers may require
> passing two independent 32-bit arguments during a reboot
> sequence, for uses-cases, where a mode requires an additional
> argument. Such drivers may not be able to use the reboot-mode
> driver. For example, ARM PSCI vendor-specific resets, need two
> arguments for its operation – reset_type and cookie, to complete
> the reset operation. If a driver wants to implement this
> firmware-based reset, it cannot use reboot-mode framework.
>
> Introduce 64-bit magic values in reboot-mode driver to
> accommodate dual 32-bit arguments when specified via device tree.
> In cases, where no second argument is passed from device tree,
> keep the upper 32-bit of magic un-changed(0) to maintain backward
> compatibility.
>
> Update the current drivers using reboot-mode for a 64-bit magic
> value.
>
> Reviewed-by: Umang Chheda <umang.chheda@oss.qualcomm.com>
> Reviewed-by: Nirmesh Kumar Singh <nirmesh.singh@oss.qualcomm.com>
> Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>
> ---
> drivers/power/reset/nvmem-reboot-mode.c | 13 +++++++++----
> drivers/power/reset/qcom-pon.c | 11 ++++++++---
> drivers/power/reset/reboot-mode.c | 19 +++++++++++++------
> drivers/power/reset/syscon-reboot-mode.c | 11 ++++++++---
> include/linux/reboot-mode.h | 3 ++-
> 5 files changed, 40 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/power/reset/nvmem-reboot-mode.c b/drivers/power/reset/nvmem-reboot-mode.c
> index 41530b70cfc48c2a83fbbd96f523d5816960a0d1..5d73dde585b1fd438b1847f884feb37cd9e4dd5c 100644
> --- a/drivers/power/reset/nvmem-reboot-mode.c
> +++ b/drivers/power/reset/nvmem-reboot-mode.c
> @@ -16,15 +16,20 @@ struct nvmem_reboot_mode {
> struct nvmem_cell *cell;
> };
>
> -static int nvmem_reboot_mode_write(struct reboot_mode_driver *reboot,
> - unsigned int magic)
> +static int nvmem_reboot_mode_write(struct reboot_mode_driver *reboot, u64 magic)
> {
> - int ret;
> struct nvmem_reboot_mode *nvmem_rbm;
> + u32 magic_32;
> + int ret;
> +
> + if (magic > U32_MAX)
> + return -EINVAL;

I believe, we need a comment in all the client driver..

> +
> + magic_32 = magic;
>
> nvmem_rbm = container_of(reboot, struct nvmem_reboot_mode, reboot);
>
> - ret = nvmem_cell_write(nvmem_rbm->cell, &magic, sizeof(magic));
> + ret = nvmem_cell_write(nvmem_rbm->cell, &magic_32, sizeof(magic_32));
> if (ret < 0)
> dev_err(reboot->dev, "update reboot mode bits failed\n");
>
> diff --git a/drivers/power/reset/qcom-pon.c b/drivers/power/reset/qcom-pon.c
> index 7e108982a582e8243c5c806bd4a793646b87189f..d0ed9431a02313a7bbaa93743c16fa1ae713ddfe 100644
> --- a/drivers/power/reset/qcom-pon.c
> +++ b/drivers/power/reset/qcom-pon.c
> @@ -27,17 +27,22 @@ struct qcom_pon {
> long reason_shift;
> };
>
> -static int qcom_pon_reboot_mode_write(struct reboot_mode_driver *reboot,
> - unsigned int magic)
> +static int qcom_pon_reboot_mode_write(struct reboot_mode_driver *reboot, u64 magic)
> {
> struct qcom_pon *pon = container_of
> (reboot, struct qcom_pon, reboot_mode);
> + u32 magic_32;
> int ret;
>

Since we are doing this change in reboot framework, client driver should know about
it too about this new check because of framework.

> + if (magic > U32_MAX || (magic << pon->reason_shift) > U32_MAX)

is this (magic << pon->reason_shift) > U32_MAX really needed ..?

> + return -EINVAL;
> +
> + magic_32 = magic << pon->reason_shift;
> +
> ret = regmap_update_bits(pon->regmap,
> pon->baseaddr + PON_SOFT_RB_SPARE,
> GENMASK(7, pon->reason_shift),
> - magic << pon->reason_shift);
> + magic_32);
> if (ret < 0)
> dev_err(pon->dev, "update reboot mode bits failed\n");
>
> diff --git a/drivers/power/reset/reboot-mode.c b/drivers/power/reset/reboot-mode.c
> index eff60d6e04df2cb84ba59d38512654336f272f8a..873ac45cd7659b214b7c21958f580ca381e0a63d 100644
> --- a/drivers/power/reset/reboot-mode.c
> +++ b/drivers/power/reset/reboot-mode.c
> @@ -19,12 +19,11 @@
>
> struct mode_info {
> const char *mode;
> - u32 magic;
> + u64 magic;
> struct list_head list;
> };
>
> -static unsigned int get_reboot_mode_magic(struct reboot_mode_driver *reboot,
> - const char *cmd)
> +static u64 get_reboot_mode_magic(struct reboot_mode_driver *reboot, const char *cmd)
> {
> const char *normal = "normal";
> struct mode_info *info;
> @@ -56,7 +55,7 @@ static int reboot_mode_notify(struct notifier_block *this,
> unsigned long mode, void *cmd)
> {
> struct reboot_mode_driver *reboot;
> - unsigned int magic;
> + u64 magic;
>
> reboot = container_of(this, struct reboot_mode_driver, reboot_notifier);
> magic = get_reboot_mode_magic(reboot, cmd);
> @@ -80,6 +79,8 @@ int reboot_mode_register(struct reboot_mode_driver *reboot, struct fwnode_handle
> struct device_node *np;
> struct property *prop;
> size_t len = strlen(PREFIX);
> + u32 magic_arg1;
> + u32 magic_arg2;
> int ret;
>
> if (!fwnode)
> @@ -101,12 +102,18 @@ int reboot_mode_register(struct reboot_mode_driver *reboot, struct fwnode_handle
> goto error;
> }
>
> - if (of_property_read_u32(np, prop->name, &info->magic)) {
> - pr_err("reboot mode %s without magic number\n", info->mode);
> + if (of_property_read_u32(np, prop->name, &magic_arg1)) {
> + pr_err("reboot mode without magic number\n");
> kfree(info);
> continue;
> }
>
> + if (of_property_read_u32_index(np, prop->name, 1, &magic_arg2))
> + magic_arg2 = 0;
> +
> + info->magic = magic_arg2;
> + info->magic = (info->magic << 32) | magic_arg1;
> +
> info->mode = kstrdup_const(prop->name + len, GFP_KERNEL);
> if (!info->mode) {
> ret = -ENOMEM;
> diff --git a/drivers/power/reset/syscon-reboot-mode.c b/drivers/power/reset/syscon-reboot-mode.c
> index e0772c9f70f7a19cd8ec8a0b7fdbbaa7ba44afd0..3cbd000c512239b12ec51987e900d260540a9dea 100644
> --- a/drivers/power/reset/syscon-reboot-mode.c
> +++ b/drivers/power/reset/syscon-reboot-mode.c
> @@ -20,16 +20,21 @@ struct syscon_reboot_mode {
> u32 mask;
> };
>
> -static int syscon_reboot_mode_write(struct reboot_mode_driver *reboot,
> - unsigned int magic)
> +static int syscon_reboot_mode_write(struct reboot_mode_driver *reboot, u64 magic)
> {
> struct syscon_reboot_mode *syscon_rbm;
> + u32 magic_32;
> int ret;
>

same here

> + if (magic > U32_MAX)
> + return -EINVAL;
> +
> + magic_32 = magic;
> +
> syscon_rbm = container_of(reboot, struct syscon_reboot_mode, reboot);
>
> ret = regmap_update_bits(syscon_rbm->map, syscon_rbm->offset,
> - syscon_rbm->mask, magic);
> + syscon_rbm->mask, magic_32);
> if (ret < 0)
> dev_err(reboot->dev, "update reboot mode bits failed\n");
>
> diff --git a/include/linux/reboot-mode.h b/include/linux/reboot-mode.h
> index 22f707ade4ba93592823ea8718d467dbfc5ffd7c..e0d3e8a54050a76f26846f456120b4c7e371d284 100644
> --- a/include/linux/reboot-mode.h
> +++ b/include/linux/reboot-mode.h
> @@ -3,11 +3,12 @@
> #define __REBOOT_MODE_H__
>
> #include <linux/fwnode.h>
> +#include <linux/types.h>
>
> struct reboot_mode_driver {
> struct device *dev;
> struct list_head head;
> - int (*write)(struct reboot_mode_driver *reboot, unsigned int magic);
> + int (*write)(struct reboot_mode_driver *reboot, u64 magic);
> struct notifier_block reboot_notifier;
> };
>
>
> --
> 2.34.1
>

--
-Mukesh Ojha