diff mbox series

power: reset: at91-reset: add sysfs interface to the power on reason

Message ID 20191017124058.19300-1-kamel.bouhara@bootlin.com (mailing list archive)
State New, archived
Headers show
Series power: reset: at91-reset: add sysfs interface to the power on reason | expand

Commit Message

Kamel BOUHARA Oct. 17, 2019, 12:40 p.m. UTC 
This patch export the power on reason through the sysfs interface and
introduce some generic reset sources.
Update the ABI documentation to list current power on sources.

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
---
 .../sysfs-devices-platform-power-on-reason    | 14 ++++++
 drivers/power/reset/at91-reset.c              | 44 +++++++++++++------
 include/linux/power/power_on_reason.h         | 19 ++++++++
 3 files changed, 64 insertions(+), 13 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
 create mode 100644 include/linux/power/power_on_reason.h

--
2.23.0

Comments

Nicolas Ferre Nov. 28, 2019, 2:48 p.m. UTC | #1 
On 17/10/2019 at 14:40, Kamel Bouhara wrote:
> This patch export the power on reason through the sysfs interface and
> introduce some generic reset sources.
> Update the ABI documentation to list current power on sources.
> 
> Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>

I don't know the status of this.
Anyway, here is my:

Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>

Thanks Kamel. Best regards,
   Nicolas

> ---
>   .../sysfs-devices-platform-power-on-reason    | 14 ++++++
>   drivers/power/reset/at91-reset.c              | 44 +++++++++++++------
>   include/linux/power/power_on_reason.h         | 19 ++++++++
>   3 files changed, 64 insertions(+), 13 deletions(-)
>   create mode 100644 Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
>   create mode 100644 include/linux/power/power_on_reason.h
> 
> diff --git a/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> new file mode 100644
> index 000000000000..83daeb9b1aa2
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> @@ -0,0 +1,14 @@
> +What:		/sys/devices/platform/.../power_on_reason
> +
> +Date:		October 2019
> +KernelVersion:	5.4
> +Contact:	Kamel Bouhara <kamel.bouhara@bootlin.com>
> +Description:	This file shows system power on reason.
> +		The possible sources are:
> +		General System Power-ON, RTC wakeup, Watchdog timeout,
> +		Software Reset, User pressed reset button,
> +		CPU Clock failure, 32.768kHz Oscillator Failure,
> +		Low power mode exit, Unknown.
> +
> +		The file is read only.
> +
> diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
> index 44ca983a49a1..3cb2df40af37 100644
> --- a/drivers/power/reset/at91-reset.c
> +++ b/drivers/power/reset/at91-reset.c
> @@ -17,7 +17,7 @@
>   #include <linux/of_address.h>
>   #include <linux/platform_device.h>
>   #include <linux/reboot.h>
> -
> +#include <linux/power/power_on_reason.h>
>   #include <soc/at91/at91sam9_ddrsdr.h>
>   #include <soc/at91/at91sam9_sdramc.h>
> 
> @@ -146,42 +146,42 @@ static int samx7_restart(struct notifier_block *this, unsigned long mode,
>   	return NOTIFY_DONE;
>   }
> 
> -static void __init at91_reset_status(struct platform_device *pdev)
> +static const char *at91_reset_reason(struct platform_device *pdev)
>   {
>   	const char *reason;
>   	u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
> 
>   	switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
>   	case RESET_TYPE_GENERAL:
> -		reason = "general reset";
> +		reason = POWER_ON_REASON_GENERAL;
>   		break;
>   	case RESET_TYPE_WAKEUP:
> -		reason = "wakeup";
> +		reason = POWER_ON_REASON_RTC;
>   		break;
>   	case RESET_TYPE_WATCHDOG:
> -		reason = "watchdog reset";
> +		reason = POWER_ON_REASON_WATCHDOG;
>   		break;
>   	case RESET_TYPE_SOFTWARE:
> -		reason = "software reset";
> +		reason = POWER_ON_REASON_SOFTWARE;
>   		break;
>   	case RESET_TYPE_USER:
> -		reason = "user reset";
> +		reason = POWER_ON_REASON_USER;
>   		break;
>   	case RESET_TYPE_CPU_FAIL:
> -		reason = "CPU clock failure detection";
> +		reason = POWER_ON_REASON_CPU_FAIL;
>   		break;
>   	case RESET_TYPE_XTAL_FAIL:
> -		reason = "32.768 kHz crystal failure detection";
> +		reason = POWER_ON_REASON_XTAL_FAIL;
>   		break;
>   	case RESET_TYPE_ULP2:
> -		reason = "ULP2 reset";
> +		reason = POWER_ON_REASON_LOW_POWER;
>   		break;
>   	default:
> -		reason = "unknown reset";
> +		reason = POWER_ON_REASON_UNKNOWN;
>   		break;
>   	}
> 
> -	dev_info(&pdev->dev, "Starting after %s\n", reason);
> +	return reason;
>   }
> 
>   static const struct of_device_id at91_ramc_of_match[] = {
> @@ -204,6 +204,17 @@ static struct notifier_block at91_restart_nb = {
>   	.priority = 192,
>   };
> 
> +static ssize_t power_on_reason_show(struct device *dev,
> +				    struct device_attribute *attr,
> +				    char *buf)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +
> +	return sprintf(buf, "%s\n", at91_reset_reason(pdev));
> +}
> +
> +static DEVICE_ATTR_RO(power_on_reason);
> +
>   static int __init at91_reset_probe(struct platform_device *pdev)
>   {
>   	const struct of_device_id *match;
> @@ -248,7 +259,14 @@ static int __init at91_reset_probe(struct platform_device *pdev)
>   		return ret;
>   	}
> 
> -	at91_reset_status(pdev);
> +	ret = device_create_file(&pdev->dev, &dev_attr_power_on_reason);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Could not create sysfs entry\n");
> +		return ret;
> +	}
> +
> +	dev_info(&pdev->dev, "Starting after %s reset\n",
> +		 at91_reset_reason(pdev));
> 
>   	return 0;
>   }
> diff --git a/include/linux/power/power_on_reason.h b/include/linux/power/power_on_reason.h
> new file mode 100644
> index 000000000000..9978cc757427
> --- /dev/null
> +++ b/include/linux/power/power_on_reason.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Author: Kamel Bouhra <kamel.bouhara@bootlin.com>
> + */
> +
> +#ifndef POWER_ON_REASON_H
> +#define POWER_ON_REASON_H
> +
> +#define POWER_ON_REASON_GENERAL "General"
> +#define POWER_ON_REASON_RTC "RTC wakeup"
> +#define POWER_ON_REASON_WATCHDOG "Watchdog timeout"
> +#define POWER_ON_REASON_SOFTWARE "Software"
> +#define POWER_ON_REASON_USER "User"
> +#define POWER_ON_REASON_CPU_FAIL "CPU Clock Failure"
> +#define POWER_ON_REASON_XTAL_FAIL "32.768k Crystal oscillator Failure"
> +#define POWER_ON_REASON_LOW_POWER "Low power exit"
> +#define POWER_ON_REASON_UNKNOWN "Unknown"
> +
> +#endif /* POWER_ON_REASON_H */
> --
> 2.23.0
> 
> 
>
Claudiu Beznea Nov. 29, 2019, 10:57 a.m. UTC | #2 
Hi Kamel,

On 17.10.2019 15:40, Kamel Bouhara wrote:
> This patch export the power on reason through the sysfs interface and
> introduce some generic reset sources.
> Update the ABI documentation to list current power on sources.
> 
> Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
> ---
>  .../sysfs-devices-platform-power-on-reason    | 14 ++++++
>  drivers/power/reset/at91-reset.c              | 44 +++++++++++++------
>  include/linux/power/power_on_reason.h         | 19 ++++++++
>  3 files changed, 64 insertions(+), 13 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
>  create mode 100644 include/linux/power/power_on_reason.h
> 
> diff --git a/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> new file mode 100644
> index 000000000000..83daeb9b1aa2
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> @@ -0,0 +1,14 @@
> +What:		/sys/devices/platform/.../power_on_reason
> +
> +Date:		October 2019
> +KernelVersion:	5.4
> +Contact:	Kamel Bouhara <kamel.bouhara@bootlin.com>
> +Description:	This file shows system power on reason.
> +		The possible sources are:
> +		General System Power-ON, RTC wakeup, Watchdog timeout,
> +		Software Reset, User pressed reset button,
> +		CPU Clock failure, 32.768kHz Oscillator Failure,
> +		Low power mode exit, Unknown.
> +
> +		The file is read only.
> +
> diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
> index 44ca983a49a1..3cb2df40af37 100644
> --- a/drivers/power/reset/at91-reset.c
> +++ b/drivers/power/reset/at91-reset.c
> @@ -17,7 +17,7 @@
>  #include <linux/of_address.h>
>  #include <linux/platform_device.h>
>  #include <linux/reboot.h>
> -
> +#include <linux/power/power_on_reason.h>
>  #include <soc/at91/at91sam9_ddrsdr.h>
>  #include <soc/at91/at91sam9_sdramc.h>
> 
> @@ -146,42 +146,42 @@ static int samx7_restart(struct notifier_block *this, unsigned long mode,
>  	return NOTIFY_DONE;
>  }
> 
> -static void __init at91_reset_status(struct platform_device *pdev)
> +static const char *at91_reset_reason(struct platform_device *pdev)
>  {
>  	const char *reason;
>  	u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
> 
>  	switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
>  	case RESET_TYPE_GENERAL:
> -		reason = "general reset";
> +		reason = POWER_ON_REASON_GENERAL;
>  		break;
>  	case RESET_TYPE_WAKEUP:
> -		reason = "wakeup";
> +		reason = POWER_ON_REASON_RTC;
>  		break;
>  	case RESET_TYPE_WATCHDOG:
> -		reason = "watchdog reset";
> +		reason = POWER_ON_REASON_WATCHDOG;
>  		break;
>  	case RESET_TYPE_SOFTWARE:
> -		reason = "software reset";
> +		reason = POWER_ON_REASON_SOFTWARE;
>  		break;
>  	case RESET_TYPE_USER:
> -		reason = "user reset";
> +		reason = POWER_ON_REASON_USER;
>  		break;
>  	case RESET_TYPE_CPU_FAIL:
> -		reason = "CPU clock failure detection";
> +		reason = POWER_ON_REASON_CPU_FAIL;
>  		break;
>  	case RESET_TYPE_XTAL_FAIL:
> -		reason = "32.768 kHz crystal failure detection";
> +		reason = POWER_ON_REASON_XTAL_FAIL;
>  		break;
>  	case RESET_TYPE_ULP2:
> -		reason = "ULP2 reset";
> +		reason = POWER_ON_REASON_LOW_POWER;
>  		break;
>  	default:
> -		reason = "unknown reset";
> +		reason = POWER_ON_REASON_UNKNOWN;
>  		break;
>  	}
> 
> -	dev_info(&pdev->dev, "Starting after %s\n", reason);
> +	return reason;
>  }
> 
>  static const struct of_device_id at91_ramc_of_match[] = {
> @@ -204,6 +204,17 @@ static struct notifier_block at91_restart_nb = {
>  	.priority = 192,
>  };
> 
> +static ssize_t power_on_reason_show(struct device *dev,
> +				    struct device_attribute *attr,
> +				    char *buf)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +
> +	return sprintf(buf, "%s\n", at91_reset_reason(pdev));
> +}
> +
> +static DEVICE_ATTR_RO(power_on_reason);
> +
>  static int __init at91_reset_probe(struct platform_device *pdev)
>  {
>  	const struct of_device_id *match;
> @@ -248,7 +259,14 @@ static int __init at91_reset_probe(struct platform_device *pdev)
>  		return ret;
>  	}
> 
> -	at91_reset_status(pdev);
> +	ret = device_create_file(&pdev->dev, &dev_attr_power_on_reason);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Could not create sysfs entry\n");
> +		return ret;
> +	}
> +
> +	dev_info(&pdev->dev, "Starting after %s reset\n",
> +		 at91_reset_reason(pdev));
> 
>  	return 0;
>  }
> diff --git a/include/linux/power/power_on_reason.h b/include/linux/power/power_on_reason.h
> new file mode 100644
> index 000000000000..9978cc757427
> --- /dev/null
> +++ b/include/linux/power/power_on_reason.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Author: Kamel Bouhra <kamel.bouhara@bootlin.com>
> + */
> +
> +#ifndef POWER_ON_REASON_H
> +#define POWER_ON_REASON_H
> +
> +#define POWER_ON_REASON_GENERAL "General"
> +#define POWER_ON_REASON_RTC "RTC wakeup"
> +#define POWER_ON_REASON_WATCHDOG "Watchdog timeout"
> +#define POWER_ON_REASON_SOFTWARE "Software"
> +#define POWER_ON_REASON_USER "User"
> +#define POWER_ON_REASON_CPU_FAIL "CPU Clock Failure"
> +#define POWER_ON_REASON_XTAL_FAIL "32.768k Crystal oscillator Failure"
> +#define POWER_ON_REASON_LOW_POWER "Low power exit"
> +#define POWER_ON_REASON_UNKNOWN "Unknown"
> +
> +#endif /* POWER_ON_REASON_H */

Is this new header necessary?

Thank you,
Claudiu Beznea

> --
> 2.23.0
> 
>
Alexandre Belloni Nov. 29, 2019, 11:02 a.m. UTC | #3 
On 29/11/2019 10:57:45+0000, Claudiu.Beznea@microchip.com wrote:
> Hi Kamel,
> 
> On 17.10.2019 15:40, Kamel Bouhara wrote:
> > This patch export the power on reason through the sysfs interface and
> > introduce some generic reset sources.
> > Update the ABI documentation to list current power on sources.
> > 
> > Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
> > ---
> >  .../sysfs-devices-platform-power-on-reason    | 14 ++++++
> >  drivers/power/reset/at91-reset.c              | 44 +++++++++++++------
> >  include/linux/power/power_on_reason.h         | 19 ++++++++
> >  3 files changed, 64 insertions(+), 13 deletions(-)
> >  create mode 100644 Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> >  create mode 100644 include/linux/power/power_on_reason.h
> > 
> > diff --git a/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> > new file mode 100644
> > index 000000000000..83daeb9b1aa2
> > --- /dev/null
> > +++ b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> > @@ -0,0 +1,14 @@
> > +What:		/sys/devices/platform/.../power_on_reason
> > +
> > +Date:		October 2019
> > +KernelVersion:	5.4
> > +Contact:	Kamel Bouhara <kamel.bouhara@bootlin.com>
> > +Description:	This file shows system power on reason.
> > +		The possible sources are:
> > +		General System Power-ON, RTC wakeup, Watchdog timeout,
> > +		Software Reset, User pressed reset button,
> > +		CPU Clock failure, 32.768kHz Oscillator Failure,
> > +		Low power mode exit, Unknown.
> > +
> > +		The file is read only.
> > +
> > diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
> > index 44ca983a49a1..3cb2df40af37 100644
> > --- a/drivers/power/reset/at91-reset.c
> > +++ b/drivers/power/reset/at91-reset.c
> > @@ -17,7 +17,7 @@
> >  #include <linux/of_address.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/reboot.h>
> > -
> > +#include <linux/power/power_on_reason.h>
> >  #include <soc/at91/at91sam9_ddrsdr.h>
> >  #include <soc/at91/at91sam9_sdramc.h>
> > 
> > @@ -146,42 +146,42 @@ static int samx7_restart(struct notifier_block *this, unsigned long mode,
> >  	return NOTIFY_DONE;
> >  }
> > 
> > -static void __init at91_reset_status(struct platform_device *pdev)
> > +static const char *at91_reset_reason(struct platform_device *pdev)
> >  {
> >  	const char *reason;
> >  	u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
> > 
> >  	switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
> >  	case RESET_TYPE_GENERAL:
> > -		reason = "general reset";
> > +		reason = POWER_ON_REASON_GENERAL;
> >  		break;
> >  	case RESET_TYPE_WAKEUP:
> > -		reason = "wakeup";
> > +		reason = POWER_ON_REASON_RTC;
> >  		break;
> >  	case RESET_TYPE_WATCHDOG:
> > -		reason = "watchdog reset";
> > +		reason = POWER_ON_REASON_WATCHDOG;
> >  		break;
> >  	case RESET_TYPE_SOFTWARE:
> > -		reason = "software reset";
> > +		reason = POWER_ON_REASON_SOFTWARE;
> >  		break;
> >  	case RESET_TYPE_USER:
> > -		reason = "user reset";
> > +		reason = POWER_ON_REASON_USER;
> >  		break;
> >  	case RESET_TYPE_CPU_FAIL:
> > -		reason = "CPU clock failure detection";
> > +		reason = POWER_ON_REASON_CPU_FAIL;
> >  		break;
> >  	case RESET_TYPE_XTAL_FAIL:
> > -		reason = "32.768 kHz crystal failure detection";
> > +		reason = POWER_ON_REASON_XTAL_FAIL;
> >  		break;
> >  	case RESET_TYPE_ULP2:
> > -		reason = "ULP2 reset";
> > +		reason = POWER_ON_REASON_LOW_POWER;
> >  		break;
> >  	default:
> > -		reason = "unknown reset";
> > +		reason = POWER_ON_REASON_UNKNOWN;
> >  		break;
> >  	}
> > 
> > -	dev_info(&pdev->dev, "Starting after %s\n", reason);
> > +	return reason;
> >  }
> > 
> >  static const struct of_device_id at91_ramc_of_match[] = {
> > @@ -204,6 +204,17 @@ static struct notifier_block at91_restart_nb = {
> >  	.priority = 192,
> >  };
> > 
> > +static ssize_t power_on_reason_show(struct device *dev,
> > +				    struct device_attribute *attr,
> > +				    char *buf)
> > +{
> > +	struct platform_device *pdev = to_platform_device(dev);
> > +
> > +	return sprintf(buf, "%s\n", at91_reset_reason(pdev));
> > +}
> > +
> > +static DEVICE_ATTR_RO(power_on_reason);
> > +
> >  static int __init at91_reset_probe(struct platform_device *pdev)
> >  {
> >  	const struct of_device_id *match;
> > @@ -248,7 +259,14 @@ static int __init at91_reset_probe(struct platform_device *pdev)
> >  		return ret;
> >  	}
> > 
> > -	at91_reset_status(pdev);
> > +	ret = device_create_file(&pdev->dev, &dev_attr_power_on_reason);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Could not create sysfs entry\n");
> > +		return ret;
> > +	}
> > +
> > +	dev_info(&pdev->dev, "Starting after %s reset\n",
> > +		 at91_reset_reason(pdev));
> > 
> >  	return 0;
> >  }
> > diff --git a/include/linux/power/power_on_reason.h b/include/linux/power/power_on_reason.h
> > new file mode 100644
> > index 000000000000..9978cc757427
> > --- /dev/null
> > +++ b/include/linux/power/power_on_reason.h
> > @@ -0,0 +1,19 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Author: Kamel Bouhra <kamel.bouhara@bootlin.com>
> > + */
> > +
> > +#ifndef POWER_ON_REASON_H
> > +#define POWER_ON_REASON_H
> > +
> > +#define POWER_ON_REASON_GENERAL "General"
> > +#define POWER_ON_REASON_RTC "RTC wakeup"
> > +#define POWER_ON_REASON_WATCHDOG "Watchdog timeout"
> > +#define POWER_ON_REASON_SOFTWARE "Software"
> > +#define POWER_ON_REASON_USER "User"
> > +#define POWER_ON_REASON_CPU_FAIL "CPU Clock Failure"
> > +#define POWER_ON_REASON_XTAL_FAIL "32.768k Crystal oscillator Failure"
> > +#define POWER_ON_REASON_LOW_POWER "Low power exit"
> > +#define POWER_ON_REASON_UNKNOWN "Unknown"
> > +
> > +#endif /* POWER_ON_REASON_H */
> 
> Is this new header necessary?
> 

Yes because we want other drivers to be able to reuse them as-is so the
ABI is stable.
Eugen Hristev Nov. 29, 2019, 11:15 a.m. UTC | #4 
On 29.11.2019 13:02, Alexandre Belloni wrote:

> On 29/11/2019 10:57:45+0000, Claudiu.Beznea@microchip.com wrote:
>> Hi Kamel,
>>
>> On 17.10.2019 15:40, Kamel Bouhara wrote:
>>> This patch export the power on reason through the sysfs interface and
>>> introduce some generic reset sources.
>>> Update the ABI documentation to list current power on sources.
>>>
>>> Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
>>> ---
>>>   .../sysfs-devices-platform-power-on-reason    | 14 ++++++
>>>   drivers/power/reset/at91-reset.c              | 44 +++++++++++++------
>>>   include/linux/power/power_on_reason.h         | 19 ++++++++
>>>   3 files changed, 64 insertions(+), 13 deletions(-)
>>>   create mode 100644 Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
>>>   create mode 100644 include/linux/power/power_on_reason.h
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
>>> new file mode 100644
>>> index 000000000000..83daeb9b1aa2
>>> --- /dev/null
>>> +++ b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
>>> @@ -0,0 +1,14 @@
>>> +What:              /sys/devices/platform/.../power_on_reason
>>> +
>>> +Date:              October 2019
>>> +KernelVersion:     5.4
>>> +Contact:   Kamel Bouhara <kamel.bouhara@bootlin.com>
>>> +Description:       This file shows system power on reason.
>>> +           The possible sources are:
>>> +           General System Power-ON, RTC wakeup, Watchdog timeout,
>>> +           Software Reset, User pressed reset button,
>>> +           CPU Clock failure, 32.768kHz Oscillator Failure,
>>> +           Low power mode exit, Unknown.
>>> +
>>> +           The file is read only.
>>> +
>>> diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
>>> index 44ca983a49a1..3cb2df40af37 100644
>>> --- a/drivers/power/reset/at91-reset.c
>>> +++ b/drivers/power/reset/at91-reset.c
>>> @@ -17,7 +17,7 @@
>>>   #include <linux/of_address.h>
>>>   #include <linux/platform_device.h>
>>>   #include <linux/reboot.h>
>>> -
>>> +#include <linux/power/power_on_reason.h>
>>>   #include <soc/at91/at91sam9_ddrsdr.h>
>>>   #include <soc/at91/at91sam9_sdramc.h>
>>>
>>> @@ -146,42 +146,42 @@ static int samx7_restart(struct notifier_block *this, unsigned long mode,
>>>      return NOTIFY_DONE;
>>>   }
>>>
>>> -static void __init at91_reset_status(struct platform_device *pdev)
>>> +static const char *at91_reset_reason(struct platform_device *pdev)
>>>   {
>>>      const char *reason;
>>>      u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
>>>
>>>      switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
>>>      case RESET_TYPE_GENERAL:
>>> -           reason = "general reset";
>>> +           reason = POWER_ON_REASON_GENERAL;
>>>              break;
>>>      case RESET_TYPE_WAKEUP:
>>> -           reason = "wakeup";
>>> +           reason = POWER_ON_REASON_RTC;
>>>              break;
>>>      case RESET_TYPE_WATCHDOG:
>>> -           reason = "watchdog reset";
>>> +           reason = POWER_ON_REASON_WATCHDOG;
>>>              break;
>>>      case RESET_TYPE_SOFTWARE:
>>> -           reason = "software reset";
>>> +           reason = POWER_ON_REASON_SOFTWARE;
>>>              break;
>>>      case RESET_TYPE_USER:
>>> -           reason = "user reset";
>>> +           reason = POWER_ON_REASON_USER;
>>>              break;
>>>      case RESET_TYPE_CPU_FAIL:
>>> -           reason = "CPU clock failure detection";
>>> +           reason = POWER_ON_REASON_CPU_FAIL;
>>>              break;
>>>      case RESET_TYPE_XTAL_FAIL:
>>> -           reason = "32.768 kHz crystal failure detection";
>>> +           reason = POWER_ON_REASON_XTAL_FAIL;
>>>              break;
>>>      case RESET_TYPE_ULP2:
>>> -           reason = "ULP2 reset";
>>> +           reason = POWER_ON_REASON_LOW_POWER;
>>>              break;
>>>      default:
>>> -           reason = "unknown reset";
>>> +           reason = POWER_ON_REASON_UNKNOWN;
>>>              break;
>>>      }
>>>
>>> -   dev_info(&pdev->dev, "Starting after %s\n", reason);
>>> +   return reason;
>>>   }
>>>
>>>   static const struct of_device_id at91_ramc_of_match[] = {
>>> @@ -204,6 +204,17 @@ static struct notifier_block at91_restart_nb = {
>>>      .priority = 192,
>>>   };
>>>
>>> +static ssize_t power_on_reason_show(struct device *dev,
>>> +                               struct device_attribute *attr,
>>> +                               char *buf)
>>> +{
>>> +   struct platform_device *pdev = to_platform_device(dev);
>>> +
>>> +   return sprintf(buf, "%s\n", at91_reset_reason(pdev));
>>> +}
>>> +
>>> +static DEVICE_ATTR_RO(power_on_reason);
>>> +
>>>   static int __init at91_reset_probe(struct platform_device *pdev)
>>>   {
>>>      const struct of_device_id *match;
>>> @@ -248,7 +259,14 @@ static int __init at91_reset_probe(struct platform_device *pdev)
>>>              return ret;
>>>      }
>>>
>>> -   at91_reset_status(pdev);
>>> +   ret = device_create_file(&pdev->dev, &dev_attr_power_on_reason);
>>> +   if (ret) {
>>> +           dev_err(&pdev->dev, "Could not create sysfs entry\n");
>>> +           return ret;
>>> +   }
>>> +
>>> +   dev_info(&pdev->dev, "Starting after %s reset\n",
>>> +            at91_reset_reason(pdev));
>>>
>>>      return 0;
>>>   }
>>> diff --git a/include/linux/power/power_on_reason.h b/include/linux/power/power_on_reason.h
>>> new file mode 100644
>>> index 000000000000..9978cc757427
>>> --- /dev/null
>>> +++ b/include/linux/power/power_on_reason.h
>>> @@ -0,0 +1,19 @@
>>> +/* SPDX-License-Identifier: GPL-2.0-only */
>>> +/*
>>> + * Author: Kamel Bouhra <kamel.bouhara@bootlin.com>
>>> + */
>>> +
>>> +#ifndef POWER_ON_REASON_H
>>> +#define POWER_ON_REASON_H
>>> +
>>> +#define POWER_ON_REASON_GENERAL "General"
>>> +#define POWER_ON_REASON_RTC "RTC wakeup"
>>> +#define POWER_ON_REASON_WATCHDOG "Watchdog timeout"
>>> +#define POWER_ON_REASON_SOFTWARE "Software"
>>> +#define POWER_ON_REASON_USER "User"
>>> +#define POWER_ON_REASON_CPU_FAIL "CPU Clock Failure"
>>> +#define POWER_ON_REASON_XTAL_FAIL "32.768k Crystal oscillator Failure"

Hi,

Looks rather odd to have a hardcoded crystal value inside a generic header.
Also how is REASON_CPU_FAIL related to CPU Clock ?

Eugen

>>> +#define POWER_ON_REASON_LOW_POWER "Low power exit"
>>> +#define POWER_ON_REASON_UNKNOWN "Unknown"
>>> +
>>> +#endif /* POWER_ON_REASON_H */
>>
>> Is this new header necessary?
>>
> 
> Yes because we want other drivers to be able to reuse them as-is so the
> ABI is stable.
> 
> --
> Alexandre Belloni, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
Alexandre Belloni Nov. 29, 2019, 3:40 p.m. UTC | #5 
On 29/11/2019 11:15:18+0000, Eugen.Hristev@microchip.com wrote:
> 
> 
> On 29.11.2019 13:02, Alexandre Belloni wrote:
> 
> > On 29/11/2019 10:57:45+0000, Claudiu.Beznea@microchip.com wrote:
> >> Hi Kamel,
> >>
> >> On 17.10.2019 15:40, Kamel Bouhara wrote:
> >>> This patch export the power on reason through the sysfs interface and
> >>> introduce some generic reset sources.
> >>> Update the ABI documentation to list current power on sources.
> >>>
> >>> Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
> >>> ---
> >>>   .../sysfs-devices-platform-power-on-reason    | 14 ++++++
> >>>   drivers/power/reset/at91-reset.c              | 44 +++++++++++++------
> >>>   include/linux/power/power_on_reason.h         | 19 ++++++++
> >>>   3 files changed, 64 insertions(+), 13 deletions(-)
> >>>   create mode 100644 Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> >>>   create mode 100644 include/linux/power/power_on_reason.h
> >>>
> >>> diff --git a/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> >>> new file mode 100644
> >>> index 000000000000..83daeb9b1aa2
> >>> --- /dev/null
> >>> +++ b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> >>> @@ -0,0 +1,14 @@
> >>> +What:              /sys/devices/platform/.../power_on_reason
> >>> +
> >>> +Date:              October 2019
> >>> +KernelVersion:     5.4
> >>> +Contact:   Kamel Bouhara <kamel.bouhara@bootlin.com>
> >>> +Description:       This file shows system power on reason.
> >>> +           The possible sources are:
> >>> +           General System Power-ON, RTC wakeup, Watchdog timeout,
> >>> +           Software Reset, User pressed reset button,
> >>> +           CPU Clock failure, 32.768kHz Oscillator Failure,
> >>> +           Low power mode exit, Unknown.
> >>> +
> >>> +           The file is read only.
> >>> +
> >>> diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
> >>> index 44ca983a49a1..3cb2df40af37 100644
> >>> --- a/drivers/power/reset/at91-reset.c
> >>> +++ b/drivers/power/reset/at91-reset.c
> >>> @@ -17,7 +17,7 @@
> >>>   #include <linux/of_address.h>
> >>>   #include <linux/platform_device.h>
> >>>   #include <linux/reboot.h>
> >>> -
> >>> +#include <linux/power/power_on_reason.h>
> >>>   #include <soc/at91/at91sam9_ddrsdr.h>
> >>>   #include <soc/at91/at91sam9_sdramc.h>
> >>>
> >>> @@ -146,42 +146,42 @@ static int samx7_restart(struct notifier_block *this, unsigned long mode,
> >>>      return NOTIFY_DONE;
> >>>   }
> >>>
> >>> -static void __init at91_reset_status(struct platform_device *pdev)
> >>> +static const char *at91_reset_reason(struct platform_device *pdev)
> >>>   {
> >>>      const char *reason;
> >>>      u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
> >>>
> >>>      switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
> >>>      case RESET_TYPE_GENERAL:
> >>> -           reason = "general reset";
> >>> +           reason = POWER_ON_REASON_GENERAL;
> >>>              break;
> >>>      case RESET_TYPE_WAKEUP:
> >>> -           reason = "wakeup";
> >>> +           reason = POWER_ON_REASON_RTC;
> >>>              break;
> >>>      case RESET_TYPE_WATCHDOG:
> >>> -           reason = "watchdog reset";
> >>> +           reason = POWER_ON_REASON_WATCHDOG;
> >>>              break;
> >>>      case RESET_TYPE_SOFTWARE:
> >>> -           reason = "software reset";
> >>> +           reason = POWER_ON_REASON_SOFTWARE;
> >>>              break;
> >>>      case RESET_TYPE_USER:
> >>> -           reason = "user reset";
> >>> +           reason = POWER_ON_REASON_USER;
> >>>              break;
> >>>      case RESET_TYPE_CPU_FAIL:
> >>> -           reason = "CPU clock failure detection";
> >>> +           reason = POWER_ON_REASON_CPU_FAIL;
> >>>              break;
> >>>      case RESET_TYPE_XTAL_FAIL:
> >>> -           reason = "32.768 kHz crystal failure detection";
> >>> +           reason = POWER_ON_REASON_XTAL_FAIL;
> >>>              break;
> >>>      case RESET_TYPE_ULP2:
> >>> -           reason = "ULP2 reset";
> >>> +           reason = POWER_ON_REASON_LOW_POWER;
> >>>              break;
> >>>      default:
> >>> -           reason = "unknown reset";
> >>> +           reason = POWER_ON_REASON_UNKNOWN;
> >>>              break;
> >>>      }
> >>>
> >>> -   dev_info(&pdev->dev, "Starting after %s\n", reason);
> >>> +   return reason;
> >>>   }
> >>>
> >>>   static const struct of_device_id at91_ramc_of_match[] = {
> >>> @@ -204,6 +204,17 @@ static struct notifier_block at91_restart_nb = {
> >>>      .priority = 192,
> >>>   };
> >>>
> >>> +static ssize_t power_on_reason_show(struct device *dev,
> >>> +                               struct device_attribute *attr,
> >>> +                               char *buf)
> >>> +{
> >>> +   struct platform_device *pdev = to_platform_device(dev);
> >>> +
> >>> +   return sprintf(buf, "%s\n", at91_reset_reason(pdev));
> >>> +}
> >>> +
> >>> +static DEVICE_ATTR_RO(power_on_reason);
> >>> +
> >>>   static int __init at91_reset_probe(struct platform_device *pdev)
> >>>   {
> >>>      const struct of_device_id *match;
> >>> @@ -248,7 +259,14 @@ static int __init at91_reset_probe(struct platform_device *pdev)
> >>>              return ret;
> >>>      }
> >>>
> >>> -   at91_reset_status(pdev);
> >>> +   ret = device_create_file(&pdev->dev, &dev_attr_power_on_reason);
> >>> +   if (ret) {
> >>> +           dev_err(&pdev->dev, "Could not create sysfs entry\n");
> >>> +           return ret;
> >>> +   }
> >>> +
> >>> +   dev_info(&pdev->dev, "Starting after %s reset\n",
> >>> +            at91_reset_reason(pdev));
> >>>
> >>>      return 0;
> >>>   }
> >>> diff --git a/include/linux/power/power_on_reason.h b/include/linux/power/power_on_reason.h
> >>> new file mode 100644
> >>> index 000000000000..9978cc757427
> >>> --- /dev/null
> >>> +++ b/include/linux/power/power_on_reason.h
> >>> @@ -0,0 +1,19 @@
> >>> +/* SPDX-License-Identifier: GPL-2.0-only */
> >>> +/*
> >>> + * Author: Kamel Bouhra <kamel.bouhara@bootlin.com>
> >>> + */
> >>> +
> >>> +#ifndef POWER_ON_REASON_H
> >>> +#define POWER_ON_REASON_H
> >>> +
> >>> +#define POWER_ON_REASON_GENERAL "General"
> >>> +#define POWER_ON_REASON_RTC "RTC wakeup"
> >>> +#define POWER_ON_REASON_WATCHDOG "Watchdog timeout"
> >>> +#define POWER_ON_REASON_SOFTWARE "Software"
> >>> +#define POWER_ON_REASON_USER "User"
> >>> +#define POWER_ON_REASON_CPU_FAIL "CPU Clock Failure"
> >>> +#define POWER_ON_REASON_XTAL_FAIL "32.768k Crystal oscillator Failure"
> 
> Hi,
> 
> Looks rather odd to have a hardcoded crystal value inside a generic header.
> Also how is REASON_CPU_FAIL related to CPU Clock ?
> 

Yes, I also think having the xtal rate is a bit too specific.
Kamel BOUHARA Dec. 2, 2019, 11:44 a.m. UTC | #6 
On Fri, Nov 29, 2019 at 11:15:18AM +0000, Eugen.Hristev@microchip.com wrote:
>
>
> On 29.11.2019 13:02, Alexandre Belloni wrote:
>
> > On 29/11/2019 10:57:45+0000, Claudiu.Beznea@microchip.com wrote:
> >> Hi Kamel,
> >>
> >> On 17.10.2019 15:40, Kamel Bouhara wrote:
> >>> This patch export the power on reason through the sysfs interface and
> >>> introduce some generic reset sources.
> >>> Update the ABI documentation to list current power on sources.
> >>>
> >>> Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
> >>> ---
> >>>   .../sysfs-devices-platform-power-on-reason    | 14 ++++++
> >>>   drivers/power/reset/at91-reset.c              | 44 +++++++++++++------
> >>>   include/linux/power/power_on_reason.h         | 19 ++++++++
> >>>   3 files changed, 64 insertions(+), 13 deletions(-)
> >>>   create mode 100644 Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> >>>   create mode 100644 include/linux/power/power_on_reason.h
> >>>
> >>> diff --git a/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> >>> new file mode 100644
> >>> index 000000000000..83daeb9b1aa2
> >>> --- /dev/null
> >>> +++ b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
> >>> @@ -0,0 +1,14 @@
> >>> +What:              /sys/devices/platform/.../power_on_reason
> >>> +
> >>> +Date:              October 2019
> >>> +KernelVersion:     5.4
> >>> +Contact:   Kamel Bouhara <kamel.bouhara@bootlin.com>
> >>> +Description:       This file shows system power on reason.
> >>> +           The possible sources are:
> >>> +           General System Power-ON, RTC wakeup, Watchdog timeout,
> >>> +           Software Reset, User pressed reset button,
> >>> +           CPU Clock failure, 32.768kHz Oscillator Failure,
> >>> +           Low power mode exit, Unknown.
> >>> +
> >>> +           The file is read only.
> >>> +
> >>> diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
> >>> index 44ca983a49a1..3cb2df40af37 100644
> >>> --- a/drivers/power/reset/at91-reset.c
> >>> +++ b/drivers/power/reset/at91-reset.c
> >>> @@ -17,7 +17,7 @@
> >>>   #include <linux/of_address.h>
> >>>   #include <linux/platform_device.h>
> >>>   #include <linux/reboot.h>
> >>> -
> >>> +#include <linux/power/power_on_reason.h>
> >>>   #include <soc/at91/at91sam9_ddrsdr.h>
> >>>   #include <soc/at91/at91sam9_sdramc.h>
> >>>
> >>> @@ -146,42 +146,42 @@ static int samx7_restart(struct notifier_block *this, unsigned long mode,
> >>>      return NOTIFY_DONE;
> >>>   }
> >>>
> >>> -static void __init at91_reset_status(struct platform_device *pdev)
> >>> +static const char *at91_reset_reason(struct platform_device *pdev)
> >>>   {
> >>>      const char *reason;
> >>>      u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
> >>>
> >>>      switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
> >>>      case RESET_TYPE_GENERAL:
> >>> -           reason = "general reset";
> >>> +           reason = POWER_ON_REASON_GENERAL;
> >>>              break;
> >>>      case RESET_TYPE_WAKEUP:
> >>> -           reason = "wakeup";
> >>> +           reason = POWER_ON_REASON_RTC;
> >>>              break;
> >>>      case RESET_TYPE_WATCHDOG:
> >>> -           reason = "watchdog reset";
> >>> +           reason = POWER_ON_REASON_WATCHDOG;
> >>>              break;
> >>>      case RESET_TYPE_SOFTWARE:
> >>> -           reason = "software reset";
> >>> +           reason = POWER_ON_REASON_SOFTWARE;
> >>>              break;
> >>>      case RESET_TYPE_USER:
> >>> -           reason = "user reset";
> >>> +           reason = POWER_ON_REASON_USER;
> >>>              break;
> >>>      case RESET_TYPE_CPU_FAIL:
> >>> -           reason = "CPU clock failure detection";
> >>> +           reason = POWER_ON_REASON_CPU_FAIL;
> >>>              break;
> >>>      case RESET_TYPE_XTAL_FAIL:
> >>> -           reason = "32.768 kHz crystal failure detection";
> >>> +           reason = POWER_ON_REASON_XTAL_FAIL;
> >>>              break;
> >>>      case RESET_TYPE_ULP2:
> >>> -           reason = "ULP2 reset";
> >>> +           reason = POWER_ON_REASON_LOW_POWER;
> >>>              break;
> >>>      default:
> >>> -           reason = "unknown reset";
> >>> +           reason = POWER_ON_REASON_UNKNOWN;
> >>>              break;
> >>>      }
> >>>
> >>> -   dev_info(&pdev->dev, "Starting after %s\n", reason);
> >>> +   return reason;
> >>>   }
> >>>
> >>>   static const struct of_device_id at91_ramc_of_match[] = {
> >>> @@ -204,6 +204,17 @@ static struct notifier_block at91_restart_nb = {
> >>>      .priority = 192,
> >>>   };
> >>>
> >>> +static ssize_t power_on_reason_show(struct device *dev,
> >>> +                               struct device_attribute *attr,
> >>> +                               char *buf)
> >>> +{
> >>> +   struct platform_device *pdev = to_platform_device(dev);
> >>> +
> >>> +   return sprintf(buf, "%s\n", at91_reset_reason(pdev));
> >>> +}
> >>> +
> >>> +static DEVICE_ATTR_RO(power_on_reason);
> >>> +
> >>>   static int __init at91_reset_probe(struct platform_device *pdev)
> >>>   {
> >>>      const struct of_device_id *match;
> >>> @@ -248,7 +259,14 @@ static int __init at91_reset_probe(struct platform_device *pdev)
> >>>              return ret;
> >>>      }
> >>>
> >>> -   at91_reset_status(pdev);
> >>> +   ret = device_create_file(&pdev->dev, &dev_attr_power_on_reason);
> >>> +   if (ret) {
> >>> +           dev_err(&pdev->dev, "Could not create sysfs entry\n");
> >>> +           return ret;
> >>> +   }
> >>> +
> >>> +   dev_info(&pdev->dev, "Starting after %s reset\n",
> >>> +            at91_reset_reason(pdev));
> >>>
> >>>      return 0;
> >>>   }
> >>> diff --git a/include/linux/power/power_on_reason.h b/include/linux/power/power_on_reason.h
> >>> new file mode 100644
> >>> index 000000000000..9978cc757427
> >>> --- /dev/null
> >>> +++ b/include/linux/power/power_on_reason.h
> >>> @@ -0,0 +1,19 @@
> >>> +/* SPDX-License-Identifier: GPL-2.0-only */
> >>> +/*
> >>> + * Author: Kamel Bouhra <kamel.bouhara@bootlin.com>
> >>> + */
> >>> +
> >>> +#ifndef POWER_ON_REASON_H
> >>> +#define POWER_ON_REASON_H
> >>> +
> >>> +#define POWER_ON_REASON_GENERAL "General"
> >>> +#define POWER_ON_REASON_RTC "RTC wakeup"
> >>> +#define POWER_ON_REASON_WATCHDOG "Watchdog timeout"
> >>> +#define POWER_ON_REASON_SOFTWARE "Software"
> >>> +#define POWER_ON_REASON_USER "User"
> >>> +#define POWER_ON_REASON_CPU_FAIL "CPU Clock Failure"
> >>> +#define POWER_ON_REASON_XTAL_FAIL "32.768k Crystal oscillator Failure"
>
> Hi,
>
> Looks rather odd to have a hardcoded crystal value inside a generic header.
> Also how is REASON_CPU_FAIL related to CPU Clock ?
>
Hi, Eugen,

I agree we should hide the crystal value.
For the reset status, I've just move those from the driver. I guess the
REASON_CPU_FAIL is related to some clock overclocking issue.

Kamel

> Eugen
>
> >>> +#define POWER_ON_REASON_LOW_POWER "Low power exit"
> >>> +#define POWER_ON_REASON_UNKNOWN "Unknown"
> >>> +
> >>> +#endif /* POWER_ON_REASON_H */
> >>
> >> Is this new header necessary?
> >>
> >
> > Yes because we want other drivers to be able to reuse them as-is so the
> > ABI is stable.
> >
> > --
> > Alexandre Belloni, Bootlin
> > Embedded Linux and Kernel engineering
> > https://bootlin.com
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> >

--
Kamel Bouhara, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
diff mbox series

Patch

diff --git a/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
new file mode 100644
index 000000000000..83daeb9b1aa2
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-platform-power-on-reason
@@ -0,0 +1,14 @@ 
+What:		/sys/devices/platform/.../power_on_reason
+
+Date:		October 2019
+KernelVersion:	5.4
+Contact:	Kamel Bouhara <kamel.bouhara@bootlin.com>
+Description:	This file shows system power on reason.
+		The possible sources are:
+		General System Power-ON, RTC wakeup, Watchdog timeout,
+		Software Reset, User pressed reset button,
+		CPU Clock failure, 32.768kHz Oscillator Failure,
+		Low power mode exit, Unknown.
+
+		The file is read only.
+
diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
index 44ca983a49a1..3cb2df40af37 100644
--- a/drivers/power/reset/at91-reset.c
+++ b/drivers/power/reset/at91-reset.c
@@ -17,7 +17,7 @@ 
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/reboot.h>
-
+#include <linux/power/power_on_reason.h>
 #include <soc/at91/at91sam9_ddrsdr.h>
 #include <soc/at91/at91sam9_sdramc.h>

@@ -146,42 +146,42 @@  static int samx7_restart(struct notifier_block *this, unsigned long mode,
 	return NOTIFY_DONE;
 }

-static void __init at91_reset_status(struct platform_device *pdev)
+static const char *at91_reset_reason(struct platform_device *pdev)
 {
 	const char *reason;
 	u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);

 	switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
 	case RESET_TYPE_GENERAL:
-		reason = "general reset";
+		reason = POWER_ON_REASON_GENERAL;
 		break;
 	case RESET_TYPE_WAKEUP:
-		reason = "wakeup";
+		reason = POWER_ON_REASON_RTC;
 		break;
 	case RESET_TYPE_WATCHDOG:
-		reason = "watchdog reset";
+		reason = POWER_ON_REASON_WATCHDOG;
 		break;
 	case RESET_TYPE_SOFTWARE:
-		reason = "software reset";
+		reason = POWER_ON_REASON_SOFTWARE;
 		break;
 	case RESET_TYPE_USER:
-		reason = "user reset";
+		reason = POWER_ON_REASON_USER;
 		break;
 	case RESET_TYPE_CPU_FAIL:
-		reason = "CPU clock failure detection";
+		reason = POWER_ON_REASON_CPU_FAIL;
 		break;
 	case RESET_TYPE_XTAL_FAIL:
-		reason = "32.768 kHz crystal failure detection";
+		reason = POWER_ON_REASON_XTAL_FAIL;
 		break;
 	case RESET_TYPE_ULP2:
-		reason = "ULP2 reset";
+		reason = POWER_ON_REASON_LOW_POWER;
 		break;
 	default:
-		reason = "unknown reset";
+		reason = POWER_ON_REASON_UNKNOWN;
 		break;
 	}

-	dev_info(&pdev->dev, "Starting after %s\n", reason);
+	return reason;
 }

 static const struct of_device_id at91_ramc_of_match[] = {
@@ -204,6 +204,17 @@  static struct notifier_block at91_restart_nb = {
 	.priority = 192,
 };

+static ssize_t power_on_reason_show(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+
+	return sprintf(buf, "%s\n", at91_reset_reason(pdev));
+}
+
+static DEVICE_ATTR_RO(power_on_reason);
+
 static int __init at91_reset_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *match;
@@ -248,7 +259,14 @@  static int __init at91_reset_probe(struct platform_device *pdev)
 		return ret;
 	}

-	at91_reset_status(pdev);
+	ret = device_create_file(&pdev->dev, &dev_attr_power_on_reason);
+	if (ret) {
+		dev_err(&pdev->dev, "Could not create sysfs entry\n");
+		return ret;
+	}
+
+	dev_info(&pdev->dev, "Starting after %s reset\n",
+		 at91_reset_reason(pdev));

 	return 0;
 }
diff --git a/include/linux/power/power_on_reason.h b/include/linux/power/power_on_reason.h
new file mode 100644
index 000000000000..9978cc757427
--- /dev/null
+++ b/include/linux/power/power_on_reason.h
@@ -0,0 +1,19 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Author: Kamel Bouhra <kamel.bouhara@bootlin.com>
+ */
+
+#ifndef POWER_ON_REASON_H
+#define POWER_ON_REASON_H
+
+#define POWER_ON_REASON_GENERAL "General"
+#define POWER_ON_REASON_RTC "RTC wakeup"
+#define POWER_ON_REASON_WATCHDOG "Watchdog timeout"
+#define POWER_ON_REASON_SOFTWARE "Software"
+#define POWER_ON_REASON_USER "User"
+#define POWER_ON_REASON_CPU_FAIL "CPU Clock Failure"
+#define POWER_ON_REASON_XTAL_FAIL "32.768k Crystal oscillator Failure"
+#define POWER_ON_REASON_LOW_POWER "Low power exit"
+#define POWER_ON_REASON_UNKNOWN "Unknown"
+
+#endif /* POWER_ON_REASON_H */