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

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Introduce a list of generic reset sources and use them to export the
power on reason through sysfs. Update the ABI documentation to describe
this new interface.

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
[Miquel Raynal: Follow-up on Kamel's work, 4 years later]
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
This commit is contained in:
Kamel Bouhara 2023-06-20 08:26:57 +02:00 committed by Sebastian Reichel
parent 7b9fc309c0
commit d40befed9a
3 changed files with 58 additions and 10 deletions
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12
Documentation/ABI/testing/sysfs-platform-power-on-reason Normal file
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@ -0,0 +1,12 @@
What: /sys/devices/platform/.../power_on_reason
Date: June 2023
KernelVersion: 6.5
Contact: Kamel Bouhara <kamel.bouhara@bootlin.com>
Description: Shows system power on reason. The following strings/reasons can
be read (the list can be extended):
"regular power-up", "RTC wakeup", "watchdog timeout",
"software reset", "reset button action", "CPU clock failure",
"crystal oscillator failure", "brown-out reset",
"unknown reason".
The file is read only.

37
drivers/power/reset/at91-reset.c
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@ -18,6 +18,7 @@
#include <linux/platform_device.h>
#include <linux/reboot.h>
#include <linux/reset-controller.h>
#include <linux/power/power_on_reason.h>
#include <soc/at91/at91sam9_ddrsdr.h>
#include <soc/at91/at91sam9_sdramc.h>
@ -149,44 +150,54 @@ static int at91_reset(struct notifier_block *this, unsigned long mode,
return NOTIFY_DONE;
}
static const char * __init at91_reset_reason(struct at91_reset *reset)
static const char *at91_reset_reason(struct at91_reset *reset)
{
u32 reg = readl(reset->rstc_base + AT91_RSTC_SR);
const char *reason;
switch ((reg & AT91_RSTC_RSTTYP) >> 8) {
case RESET_TYPE_GENERAL:
reason = "general reset";
reason = POWER_ON_REASON_REGULAR;
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_RST_BTN;
break;
case RESET_TYPE_CPU_FAIL:
reason = "CPU clock failure detection";
reason = POWER_ON_REASON_CPU_CLK_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_BROWN_OUT;
break;
default:
reason = "unknown reset";
reason = POWER_ON_REASON_UNKNOWN;
break;
}
return reason;
}
static ssize_t power_on_reason_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct platform_device *pdev = to_platform_device(dev);
struct at91_reset *reset = platform_get_drvdata(pdev);
return sprintf(buf, "%s\n", at91_reset_reason(reset));
}
static DEVICE_ATTR_RO(power_on_reason);
static const struct of_device_id at91_ramc_of_match[] = {
{
.compatible = "atmel,at91sam9260-sdramc",
@ -391,6 +402,12 @@ static int __init at91_reset_probe(struct platform_device *pdev)
if (ret)
goto disable_clk;
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\n", at91_reset_reason(reset));
return 0;

19
include/linux/power/power_on_reason.h Normal file
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@ -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_REGULAR "regular power-up"
#define POWER_ON_REASON_RTC "RTC wakeup"
#define POWER_ON_REASON_WATCHDOG "watchdog timeout"
#define POWER_ON_REASON_SOFTWARE "software reset"
#define POWER_ON_REASON_RST_BTN "reset button action"
#define POWER_ON_REASON_CPU_CLK_FAIL "CPU clock failure"
#define POWER_ON_REASON_XTAL_FAIL "crystal oscillator failure"
#define POWER_ON_REASON_BROWN_OUT "brown-out reset"
#define POWER_ON_REASON_UNKNOWN "unknown reason"
#endif /* POWER_ON_REASON_H */