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Subject[PATCH] power: reset: at91-reset: add sysfs interface to the power on reason
Date
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 */
--
2.23.0
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