Re: [PATCH v20 02/10] power: reset: reboot-mode: Add support for 64 bit magic

[Sebastian Reichel]

Hi,

On Wed, Mar 04, 2026 at 11:33:02PM +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 up-to two 32-bit arguments in below format.
> |    Higher 32 bit  |   Lower 32 bit    |
> |	 arg2	    | 	    arg1	|
> 
> Update current reboot-mode drivers for 64-bit magic.
> 
> Signed-off-by: Shivendra Pratap <shivendra.pratap@xxxxxxxxxxxxxxxx>
> ---

Reviewed-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>

-- Sebastian

>  drivers/power/reset/nvmem-reboot-mode.c  |  8 ++++----
>  drivers/power/reset/qcom-pon.c           |  6 +++---
>  drivers/power/reset/reboot-mode.c        | 16 +++++++++-------
>  drivers/power/reset/syscon-reboot-mode.c |  6 +++---
>  include/linux/reboot-mode.h              | 15 ++++++++++++++-
>  5 files changed, 33 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/power/reset/nvmem-reboot-mode.c b/drivers/power/reset/nvmem-reboot-mode.c
> index d260715fccf67f9f072bb56c5defbf885750650e..bd05d660490c686b43134f82f1eadd7665403d20 100644
> --- a/drivers/power/reset/nvmem-reboot-mode.c
> +++ b/drivers/power/reset/nvmem-reboot-mode.c
> @@ -17,10 +17,10 @@ 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)
>  {
>  	struct nvmem_reboot_mode *nvmem_rbm;
> +	u32 magic_arg1 = REBOOT_MODE_ARG1(magic);
>  	size_t buf_len;
>  	void *buf;
>  	int ret;
> @@ -32,10 +32,10 @@ static int nvmem_reboot_mode_write(struct reboot_mode_driver *reboot,
>  		return PTR_ERR(buf);
>  	kfree(buf);
>  
> -	if (buf_len > sizeof(magic))
> +	if (buf_len > sizeof(magic_arg1))
>  		return -EINVAL;
>  
> -	ret = nvmem_cell_write(nvmem_rbm->cell, &magic, buf_len);
> +	ret = nvmem_cell_write(nvmem_rbm->cell, &magic_arg1, buf_len);
>  	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..57b36e6186f80aff947fd7f5aae5ce280c65dc6b 100644
> --- a/drivers/power/reset/qcom-pon.c
> +++ b/drivers/power/reset/qcom-pon.c
> @@ -27,17 +27,17 @@ 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_arg1 = REBOOT_MODE_ARG1(magic);
>  	int ret;
>  
>  	ret = regmap_update_bits(pon->regmap,
>  				 pon->baseaddr + PON_SOFT_RB_SPARE,
>  				 GENMASK(7, pon->reason_shift),
> -				 magic << pon->reason_shift);
> +				 magic_arg1 << 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 d033043f5250a4de152a7786ef37e88a0ace3bbb..f5ab6eab210bcd9670441a4d2a301d9efdf2f322 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);
> @@ -78,7 +77,7 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
>  	struct property *prop;
>  	struct device_node *np = reboot->dev->of_node;
>  	size_t len = strlen(PREFIX);
> -	u32 magic;
> +	u32 magic[2] = {0};
>  	int ret;
>  
>  	INIT_LIST_HEAD(&reboot->head);
> @@ -87,7 +86,10 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
>  		if (strncmp(prop->name, PREFIX, len))
>  			continue;
>  
> -		if (device_property_read_u32(reboot->dev, prop->name, &magic)) {
> +		size_t count = device_property_count_u32(reboot->dev, prop->name);
> +
> +		if (!count || count > ARRAY_SIZE(magic) ||
> +		    device_property_read_u32_array(reboot->dev, prop->name, magic, count)) {
>  			pr_debug("reboot mode %s without magic number\n", prop->name);
>  			continue;
>  		}
> @@ -98,7 +100,7 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
>  			goto error;
>  		}
>  
> -		info->magic = magic;
> +		info->magic = REBOOT_MODE_MAGIC(magic[0], magic[1]);
>  		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..9f4b18c5e46f6a8bf197773ceceb80b250f57541 100644
> --- a/drivers/power/reset/syscon-reboot-mode.c
> +++ b/drivers/power/reset/syscon-reboot-mode.c
> @@ -20,16 +20,16 @@ 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_arg1 = REBOOT_MODE_ARG1(magic);
>  	int ret;
>  
>  	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_arg1);
>  	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 4a2abb38d1d612ec0fdf05eb18c98b210f631b7f..2ce189fdfff4b396d7cc6f175b30016781ae4fe9 100644
> --- a/include/linux/reboot-mode.h
> +++ b/include/linux/reboot-mode.h
> @@ -2,10 +2,23 @@
>  #ifndef __REBOOT_MODE_H__
>  #define __REBOOT_MODE_H__
>  
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +#include <linux/types.h>
> +
> +/* Construct 64-bit reboot magic: arg2 in upper 32 bits, arg1 in lower 32 */
> +#define REBOOT_MODE_MAGIC(arg1, arg2) \
> +	(FIELD_PREP(GENMASK_ULL(31, 0), (arg1)) | \
> +	 FIELD_PREP(GENMASK_ULL(63, 32), (arg2)))
> +/* Get 32 bit arg1 from 64 bit magic */
> +#define REBOOT_MODE_ARG1(magic) FIELD_GET(GENMASK_ULL(31, 0), magic)
> +/* Get 32 bit arg2 from 64 bit magic */
> +#define REBOOT_MODE_ARG2(magic) FIELD_GET(GENMASK_ULL(63, 32), magic)
> +
>  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
>

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