Re: [PATCH] power: reset: at91-reset: add sysfs interface to the power on reason

[<Claudiu.Beznea@microchip.com>]

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
> 
>