[PATCH v11 2/8] power: reset: reboot-mode: Add support for 64 bit magic
Dmitry Baryshkov
dmitry.baryshkov at oss.qualcomm.com
Fri Jul 18 11:40:25 PDT 2025
On Thu, Jul 17, 2025 at 06:16:48PM +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.
>
> Signed-off-by: Shivendra Pratap <shivendra.pratap at oss.qualcomm.com>
> ---
> drivers/power/reset/nvmem-reboot-mode.c | 5 ++---
> drivers/power/reset/qcom-pon.c | 5 ++---
> drivers/power/reset/reboot-mode.c | 27 +++++++++++++++------------
> drivers/power/reset/syscon-reboot-mode.c | 5 ++---
> include/linux/reboot-mode.h | 4 +++-
> 5 files changed, 24 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/power/reset/nvmem-reboot-mode.c b/drivers/power/reset/nvmem-reboot-mode.c
> index 41530b70cfc48c2a83fbbd96f523d5816960a0d1..e3eed943fdefa271b22e1f1891abef5c9095b9a5 100644
> --- a/drivers/power/reset/nvmem-reboot-mode.c
> +++ b/drivers/power/reset/nvmem-reboot-mode.c
> @@ -16,15 +16,14 @@ 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;
>
> 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, (u32 *)&magic, sizeof(u32));
This will work differently on BE and LE systems. Assign a temp var and
use it.
> 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..93daf93c097f970afbaf43d36b1e4f725ca7a81f 100644
> --- a/drivers/power/reset/qcom-pon.c
> +++ b/drivers/power/reset/qcom-pon.c
> @@ -27,8 +27,7 @@ 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);
> @@ -37,7 +36,7 @@ static int qcom_pon_reboot_mode_write(struct reboot_mode_driver *reboot,
> ret = regmap_update_bits(pon->regmap,
> pon->baseaddr + PON_SOFT_RB_SPARE,
> GENMASK(7, pon->reason_shift),
> - magic << pon->reason_shift);
> + ((u32)magic) << pon->reason_shift);
> 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 0269ec55106472cf2f2b12bd65704dd0114bf4a3..1196627fbf98d87eec57a3d4ee544e403e6eb946 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 struct mode_info *get_reboot_mode_info(struct reboot_mode_driver *reboot, const char *cmd)
Why? This doesn't seem relevant to u32 -> u64 conversion.
> {
> const char *normal = "normal";
> struct mode_info *info;
> @@ -35,11 +34,11 @@ static unsigned int get_reboot_mode_magic(struct reboot_mode_driver *reboot,
>
> list_for_each_entry(info, &reboot->head, list)
> if (!strcmp(info->mode, cmd))
> - return info->magic;
> + return info;
>
> /* try to match again, replacing characters impossible in DT */
> if (strscpy(cmd_, cmd, sizeof(cmd_)) == -E2BIG)
> - return 0;
> + return NULL;
>
> strreplace(cmd_, ' ', '-');
> strreplace(cmd_, ',', '-');
> @@ -47,21 +46,21 @@ static unsigned int get_reboot_mode_magic(struct reboot_mode_driver *reboot,
>
> list_for_each_entry(info, &reboot->head, list)
> if (!strcmp(info->mode, cmd_))
> - return info->magic;
> + return info;
>
> - return 0;
> + return NULL;
> }
>
> static int reboot_mode_notify(struct notifier_block *this,
> unsigned long mode, void *cmd)
> {
> struct reboot_mode_driver *reboot;
> - unsigned int magic;
> + struct mode_info *info;
>
> reboot = container_of(this, struct reboot_mode_driver, reboot_notifier);
> - magic = get_reboot_mode_magic(reboot, cmd);
> - if (magic)
> - reboot->write(reboot, magic);
> + info = get_reboot_mode_info(reboot, cmd);
> + if (info)
> + reboot->write(reboot, info->magic);
>
> return NOTIFY_DONE;
> }
> @@ -78,6 +77,7 @@ int reboot_mode_register(struct reboot_mode_driver *reboot, struct device_node *
> struct mode_info *info;
> struct property *prop;
> size_t len = strlen(PREFIX);
> + u32 magic_64;
> int ret;
>
> if (!np)
> @@ -95,12 +95,15 @@ int reboot_mode_register(struct reboot_mode_driver *reboot, struct device_node *
> goto error;
> }
>
> - if (of_property_read_u32(np, prop->name, &info->magic)) {
> + if (of_property_read_u32(np, prop->name, (u32 *)&info->magic)) {
Again, somebody didn't think about endianness.
> pr_err("reboot mode %s without magic number\n", info->mode);
> kfree(info);
> continue;
> }
>
> + if (!of_property_read_u32_index(np, prop->name, 1, &magic_64))
> + info->magic |= (u64)magic_64 << 32;
> +
> 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..6783d05e80fbc2c812b45ffe69755478af90d30a 100644
> --- a/drivers/power/reset/syscon-reboot-mode.c
> +++ b/drivers/power/reset/syscon-reboot-mode.c
> @@ -20,8 +20,7 @@ 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;
> int ret;
> @@ -29,7 +28,7 @@ static int syscon_reboot_mode_write(struct reboot_mode_driver *reboot,
> 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, (u32)magic);
> 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 36f071f4b82e1fc255d8dd679a18e537655c3179..d9d9165a8635e5d55d92197a69c7fae179ac2045 100644
> --- a/include/linux/reboot-mode.h
> +++ b/include/linux/reboot-mode.h
> @@ -2,10 +2,12 @@
> #ifndef __REBOOT_MODE_H__
> #define __REBOOT_MODE_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
>
--
With best wishes
Dmitry
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