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@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));
 	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)
 {
 	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)) {
 			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

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@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

On 7/19/2025 12:10 AM, Dmitry Baryshkov wrote:
> 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@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.
Ack.
> 
>>  	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.
yes. This function is no more needed. Will update it for u64.
> 
>>  {
>>  	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.
Ack. will update this wherever applicable.
> 
>>  			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
>>
> 

> >> +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);

As a general rule of thumb, code with casts is poor quality code. Try
to write the code without casts.

Maybe something like

      If (magic > MAX_U32)
      	   return -EINVAL;

      magic_32 = magic;

You might be able to go further, and validate that magic actually fits
into the field when you consider the << pon->reason_shift.

	Andrew

On 7/19/2025 10:27 PM, Andrew Lunn wrote:
>>>> +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);
> 
> As a general rule of thumb, code with casts is poor quality code. Try
> to write the code without casts.
> 
> Maybe something like
> 
>       If (magic > MAX_U32)
>       	   return -EINVAL;
> 
>       magic_32 = magic;
sure will update it. And in above, should it be recommended to add a explicit
cast(for any avoiding any compiler complains)?
 like: magic_32 = (u32)magic;
> 
> You might be able to go further, and validate that magic actually fits
> into the field when you consider the << pon->reason_shift.
will add a check to see make sure the value is in range after "<< pon->reason_shift".

- thanks.
> 
> 	Andrew

On Sat, Jul 19, 2025 at 11:07:47PM +0530, Shivendra Pratap wrote:
> 
> 
> On 7/19/2025 10:27 PM, Andrew Lunn wrote:
> >>>> +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);
> > 
> > As a general rule of thumb, code with casts is poor quality code. Try
> > to write the code without casts.
> > 
> > Maybe something like
> > 
> >       If (magic > MAX_U32)
> >       	   return -EINVAL;
> > 
> >       magic_32 = magic;
> sure will update it. And in above, should it be recommended to add a explicit
> cast(for any avoiding any compiler complains)?
>  like: magic_32 = (u32)magic;

I would hope the compiler/optimiser can figure out from the test the
line before that this is a safe conversion. So i don't think you need
a cast.

	Andrew

On 7/20/2025 8:46 PM, Andrew Lunn wrote:
> On Sat, Jul 19, 2025 at 11:07:47PM +0530, Shivendra Pratap wrote:
>>
>>
>> On 7/19/2025 10:27 PM, Andrew Lunn wrote:
>>>>>> +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);
>>>
>>> As a general rule of thumb, code with casts is poor quality code. Try
>>> to write the code without casts.
>>>
>>> Maybe something like
>>>
>>>       If (magic > MAX_U32)
>>>       	   return -EINVAL;
>>>
>>>       magic_32 = magic;
>> sure will update it. And in above, should it be recommended to add a explicit
>> cast(for any avoiding any compiler complains)?
>>  like: magic_32 = (u32)magic;
> 
> I would hope the compiler/optimiser can figure out from the test the
> line before that this is a safe conversion. So i don't think you need
> a cast.
sure, thanks.
> 
> 	Andrew