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Message-ID: <3827847.Gih6ie3Ah6@vostro.rjw.lan>
Date: Tue, 11 Mar 2014 20:32:08 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Ruchi Kandoi <kandoiruchi@...gle.com>
Cc: linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
ghackmann@...gle.com
Subject: Re: [PATCH] power: add an API to log wakeup reasons
On Monday, March 10, 2014 07:02:02 PM Ruchi Kandoi wrote:
> Add API log_wakeup_reason() and expose it to userspace via sysfs path
> /sys/kernel/wakeup_reasons/last_resume_reason
> This is useful for power management diagnostic purposes.
What's the use case and how is it supposed to work?
> Signed-off-by: Ruchi Kandoi <kandoiruchi@...gle.com>
> Signed-off-by: Greg Hackmann <ghackmann@...gle.com>
> ---
> include/linux/wakeup_reason.h | 23 +++++++
> kernel/power/Makefile | 2 +-
> kernel/power/wakeup_reason.c | 140 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 164 insertions(+), 1 deletion(-)
> create mode 100644 include/linux/wakeup_reason.h
> create mode 100644 kernel/power/wakeup_reason.c
>
> diff --git a/include/linux/wakeup_reason.h b/include/linux/wakeup_reason.h
> new file mode 100644
> index 0000000..7ce50f0
> --- /dev/null
> +++ b/include/linux/wakeup_reason.h
> @@ -0,0 +1,23 @@
> +/*
> + * include/linux/wakeup_reason.h
> + *
> + * Logs the reason which caused the kernel to resume
> + * from the suspend mode.
> + *
> + * Copyright (C) 2014 Google, Inc.
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef _LINUX_WAKEUP_REASON_H
> +#define _LINUX_WAKEUP_REASON_H
> +
> +void log_wakeup_reason(int irq);
> +
> +#endif /* _LINUX_WAKEUP_REASON_H */
> diff --git a/kernel/power/Makefile b/kernel/power/Makefile
> index 29472bf..f98f021 100644
> --- a/kernel/power/Makefile
> +++ b/kernel/power/Makefile
> @@ -5,7 +5,7 @@ obj-y += qos.o
> obj-$(CONFIG_PM) += main.o
> obj-$(CONFIG_VT_CONSOLE_SLEEP) += console.o
> obj-$(CONFIG_FREEZER) += process.o
> -obj-$(CONFIG_SUSPEND) += suspend.o
> +obj-$(CONFIG_SUSPEND) += suspend.o wakeup_reason.o
> obj-$(CONFIG_PM_TEST_SUSPEND) += suspend_test.o
> obj-$(CONFIG_HIBERNATION) += hibernate.o snapshot.o swap.o user.o \
> block_io.o
> diff --git a/kernel/power/wakeup_reason.c b/kernel/power/wakeup_reason.c
> new file mode 100644
> index 0000000..188a6bf
> --- /dev/null
> +++ b/kernel/power/wakeup_reason.c
> @@ -0,0 +1,140 @@
> +/*
> + * kernel/power/wakeup_reason.c
> + *
> + * Logs the reasons which caused the kernel to resume from
> + * the suspend mode.
> + *
> + * Copyright (C) 2014 Google, Inc.
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/wakeup_reason.h>
> +#include <linux/kernel.h>
> +#include <linux/irq.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kobject.h>
> +#include <linux/sysfs.h>
> +#include <linux/init.h>
> +#include <linux/spinlock.h>
> +#include <linux/notifier.h>
> +#include <linux/suspend.h>
> +
> +
> +#define MAX_WAKEUP_REASON_IRQS 32
> +static int irq_list[MAX_WAKEUP_REASON_IRQS];
> +static int irqcount;
> +static struct kobject *wakeup_reason;
> +static spinlock_t resume_reason_lock;
> +
> +static ssize_t reason_show(struct kobject *kobj, struct kobj_attribute *attr,
> + char *buf)
> +{
> + int irq_no, buf_offset = 0;
> + struct irq_desc *desc;
> + spin_lock(&resume_reason_lock);
> + for (irq_no = 0; irq_no < irqcount; irq_no++) {
> + desc = irq_to_desc(irq_list[irq_no]);
> + if (desc && desc->action && desc->action->name)
> + buf_offset += sprintf(buf + buf_offset, "%d %s\n",
> + irq_list[irq_no], desc->action->name);
> + else
> + buf_offset += sprintf(buf + buf_offset, "%d\n",
> + irq_list[irq_no]);
> + }
> + spin_unlock(&resume_reason_lock);
> + return buf_offset;
> +}
> +
> +static struct kobj_attribute resume_reason = __ATTR(last_resume_reason, 0666,
> + reason_show, NULL);
> +
> +static struct attribute *attrs[] = {
> + &resume_reason.attr,
> + NULL,
> +};
> +static struct attribute_group attr_group = {
> + .attrs = attrs,
> +};
> +
> +/*
> + * logs all the wake up reasons to the kernel
> + * stores the irqs to expose them to the userspace via sysfs
> + */
> +void log_wakeup_reason(int irq)
> +{
> + struct irq_desc *desc;
> + desc = irq_to_desc(irq);
> + if (desc && desc->action && desc->action->name)
> + printk(KERN_INFO "Resume caused by IRQ %d, %s\n", irq,
> + desc->action->name);
> + else
> + printk(KERN_INFO "Resume caused by IRQ %d\n", irq);
> +
> + spin_lock(&resume_reason_lock);
> + if (irqcount == MAX_WAKEUP_REASON_IRQS) {
> + spin_unlock(&resume_reason_lock);
> + printk(KERN_WARNING "Resume caused by more than %d IRQs\n",
> + MAX_WAKEUP_REASON_IRQS);
> + return;
> + }
> +
> + irq_list[irqcount++] = irq;
> + spin_unlock(&resume_reason_lock);
> +}
> +
> +/* Detects a suspend and clears all the previous wake up reasons*/
> +static int wakeup_reason_pm_event(struct notifier_block *notifier,
> + unsigned long pm_event, void *unused)
> +{
> + switch (pm_event) {
> + case PM_SUSPEND_PREPARE:
> + spin_lock(&resume_reason_lock);
> + irqcount = 0;
> + spin_unlock(&resume_reason_lock);
> + break;
> + default:
> + break;
> + }
> + return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block wakeup_reason_pm_notifier_block = {
> + .notifier_call = wakeup_reason_pm_event,
> +};
> +
> +/* Initializes the sysfs parameter
> + * registers the pm_event notifier
> + */
> +int __init wakeup_reason_init(void)
> +{
> + int retval;
> + spin_lock_init(&resume_reason_lock);
> + retval = register_pm_notifier(&wakeup_reason_pm_notifier_block);
> + if (retval)
> + printk(KERN_WARNING "[%s] failed to register PM notifier %d\n",
> + __func__, retval);
> +
> + wakeup_reason = kobject_create_and_add("wakeup_reasons", kernel_kobj);
> + if (!wakeup_reason) {
> + printk(KERN_WARNING "[%s] failed to create a sysfs kobject\n",
> + __func__);
> + return 1;
> + }
> + retval = sysfs_create_group(wakeup_reason, &attr_group);
> + if (retval) {
> + kobject_put(wakeup_reason);
> + printk(KERN_WARNING "[%s] failed to create a sysfs group %d\n",
> + __func__, retval);
> + }
> + return 0;
> +}
> +
> +late_initcall(wakeup_reason_init);
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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