[PATCH 1/2] PM: fast power off - core

[PATCH 1/2] PM: fast power off - core

[akuster]

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Fastpoweroff  allows a user to power down the system without using rc kill
scripts. This is used in the advent of a battery operated device about to lose
power.  The user interface is vis sysfs /sys/power/fastpoweroff. A simple cat of
the fastpoweroff will list any registered profiles.  To invoke
the profile sequence, echo {profile name} > /sys/power/fastpoweroff.

This is the core code for fastpoweroff profile support, it includes a
register/unregister and default profile callbacks.

Signed-off-by: Armin Kuster <AKuster@mvista.com>
---
 fs/super.c                    |    6 +
 kernel/power/Kconfig          |    2 
 kernel/power/Makefile         |    2 
 kernel/power/fastoff/Kconfig  |   13 +++
 kernel/power/fastoff/Makefile |    8 ++
 kernel/power/fastoff/fpo.c    |  155 ++++++++++++++++++++++++++++++++++++++++++
 kernel/power/fastoff/fpo.h    |   27 +++++++
 7 files changed, 213 insertions(+)

Index: linux-2.6_dev/kernel/power/Kconfig
===================================================================
--- linux-2.6_dev.orig/kernel/power/Kconfig
+++ linux-2.6_dev/kernel/power/Kconfig
@@ -131,3 +131,5 @@ config SUSPEND_SMP
 	bool
 	depends on HOTPLUG_CPU && X86 && PM
 	default y
+
+source "kernel/power/fastoff/Kconfig"
Index: linux-2.6_dev/kernel/power/Makefile
===================================================================
--- linux-2.6_dev.orig/kernel/power/Makefile
+++ linux-2.6_dev/kernel/power/Makefile
@@ -8,3 +8,5 @@ obj-$(CONFIG_PM_LEGACY)		+= pm.o
 obj-$(CONFIG_SOFTWARE_SUSPEND)	+= swsusp.o disk.o snapshot.o swap.o user.o
 
 obj-$(CONFIG_MAGIC_SYSRQ)	+= poweroff.o
+
+obj-$(CONFIG_FAST_POWER_OFF)	+= fastoff/
Index: linux-2.6_dev/kernel/power/fastoff/Kconfig
===================================================================
--- /dev/null
+++ linux-2.6_dev/kernel/power/fastoff/Kconfig
@@ -0,0 +1,13 @@
+#
+# Fast power off configuration
+#
+menu "Fast Power off"
+
+config FAST_POWER_OFF
+	bool "Fast power off support"
+	default y
+	depends on PM && SYSFS
+	---help---
+	  Say yes if you want core support for sysfs/power/fastoff
+
+endmenu
Index: linux-2.6_dev/kernel/power/fastoff/Makefile
===================================================================
--- /dev/null
+++ linux-2.6_dev/kernel/power/fastoff/Makefile
@@ -0,0 +1,8 @@
+#
+# Makefile for Fast Power off
+#
+# 15 Jan. 2007 Armin Kuster <akuster@mvista.com>
+#
+
+obj-$(CONFIG_FAST_POWER_OFF)	:= fpo.o
+
Index: linux-2.6_dev/kernel/power/fastoff/fpo.h
===================================================================
--- /dev/null
+++ linux-2.6_dev/kernel/power/fastoff/fpo.h
@@ -0,0 +1,27 @@
+#ifndef __FASTOFF_H__
+#define __FASTOFF_H__
+/*
+ * kernel/power/fastoff/fpo.h
+ *
+ * Author: Armin Kuster <AKuster@mvista.com, or source@mvista.com>
+ *
+ * 2006, 2007  (c) MontaVista Software, Inc. This file is licensed under
+ * the terms of the GNU General Public License version 2. This program
+ * is licensed "as is" without any warranty of any kind, whether express
+ * or implied.
+ */
+
+#define FPO_NAME_LEN 16
+
+struct fpo_driver {
+	char name[FPO_NAME_LEN];
+	int (*policy) (void);
+	struct list_head fpo_list;
+};
+
+extern int fastpoweroff_register(struct fpo_driver *fpo);
+extern void fastpoweroff_unregister(struct fpo_driver *fpo);
+extern void fastpoweroff_prepare(void);
+extern void fastpoweroff(void);
+extern void fastpoweroff_standby(void);
+#endif	/* __FASTOFF_H__ */
Index: linux-2.6_dev/kernel/power/fastoff/fpo.c
===================================================================
--- /dev/null
+++ linux-2.6_dev/kernel/power/fastoff/fpo.c
@@ -0,0 +1,155 @@
+/*
+ * kernel/power/fastoff/fpo.c
+ *
+ * This provides a sysfs interface that allows the user to
+ * bypass running rc kill scripts in the advent the user
+ * needed to power down as fast as possible. A moduler scheme
+ * has been implimented so that a user can define how they want to
+ * shutdown.
+ *
+ * Author: Armin Kuster <AKuster@mvista.com, or source@mvista.com>
+ *
+ * 2006, 2007  (c) MontaVista Software, Inc. This file is licensed under
+ * the terms of the GNU General Public License version 2. This program
+ * is licensed "as is" without any warranty of any kind, whether express
+ * or implied.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/pm.h>
+#include <linux/fs.h>
+#include <linux/reboot.h>
+#include <linux/freezer.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+
+#include "../power.h"
+#include "fpo.h"
+
+static LIST_HEAD(fastpoweroff_list);
+static DEFINE_MUTEX(fpo_mutex);
+
+extern void suspend_emergency_remount(void);
+
+static struct fpo_driver *__find_fastpoweroff(const char *name)
+{
+	struct fpo_driver *f;
+
+  	list_for_each_entry(f, &fastpoweroff_list, fpo_list) {
+		if (!strnicmp(name, f->name, strlen(f->name))) {
+			return f;
+		}
+	}
+	return NULL;
+}
+
+int fastpoweroff_register(struct fpo_driver *fpo)
+{
+	int ret;
+
+	if (!fpo || !fpo->name || !fpo->policy)
+		return -EINVAL;
+
+	mutex_lock(&fpo_mutex);
+	ret = -EBUSY;
+	if (__find_fastpoweroff(fpo->name) == NULL) {
+		ret = 0;
+		list_add_tail(&fpo->fpo_list, &fastpoweroff_list);
+	}
+	mutex_unlock(&fpo_mutex);
+	return ret;
+}
+
+EXPORT_SYMBOL_GPL(fastpoweroff_register);
+
+void fastpoweroff_unregister(struct fpo_driver *fpo)
+{
+	if (!fpo)
+		return;
+	mutex_lock(&fpo_mutex);
+	list_del(&fpo->fpo_list);
+	mutex_unlock(&fpo_mutex);
+}
+
+EXPORT_SYMBOL_GPL(fastpoweroff_unregister);
+
+void fastpoweroff_prepare(void)
+{
+	freeze_processes();
+	suspend_emergency_remount();
+}
+EXPORT_SYMBOL_GPL(fastpoweroff_prepare);
+
+void fastpoweroff(void)
+{
+	kernel_power_off();
+	printk(KERN_INFO "machine_power_off  not impliemented\n");
+}
+EXPORT_SYMBOL_GPL(fastpoweroff);
+
+void fastpoweroff_standby(void)
+{
+	/*
+	 * Power off not implemented on this platform.  Do the best we can
+	 * by powering off all devices and entering standby mode, re-entering
+	 * each time awoken.
+	 */
+	printk(KERN_INFO "Fallback plan...suspend devices\n");
+	device_power_down(PMSG_SUSPEND);
+	while (1)
+		pm_ops && pm_ops->enter(PM_SUSPEND_STANDBY);
+}
+EXPORT_SYMBOL_GPL(fastpoweroff_standby);
+
+/* sysfs setup */
+static ssize_t fastpoweroff_show(struct subsystem *subsys, char *buf)
+{
+	char *s = buf;
+	struct fpo_driver *f;
+
+  	list_for_each_entry(f, &fastpoweroff_list, fpo_list) {
+		s += sprintf(s, "%s ", f->name);
+	}
+	s += sprintf(s, "\n");
+	return (s - buf);
+}
+
+static ssize_t fastpoweroff_store(struct subsystem *subsys, const char *buf,
+				size_t n)
+{
+	struct fpo_driver *fpo;
+
+
+	if (n > FPO_NAME_LEN)
+		return -EINVAL;
+
+	if ((fpo = __find_fastpoweroff(buf)) == NULL) {
+		printk(KERN_ERR "PM: fastpoweroff: not a valid profile\n");
+		return -EINVAL;
+	}
+
+	if (fpo->policy)
+		fpo->policy();
+
+	return n;
+}
+
+power_attr(fastpoweroff);
+
+static int __init fastpoweroff_init(void)
+{
+	int error;
+	printk(KERN_INFO "PM: Fastpoweoff 1.0\n");
+	error = subsys_create_file(&power_subsys, &fastpoweroff_attr);
+	if (error)
+		printk(KERN_ERR
+		       "PM: Fastpoweoff -  Sysfs attribute export failed with error %d.\n",
+		       error);
+	return error;
+}
+
+core_initcall(fastpoweroff_init);
+
Index: linux-2.6_dev/fs/super.c
===================================================================
--- linux-2.6_dev.orig/fs/super.c
+++ linux-2.6_dev/fs/super.c
@@ -649,6 +649,12 @@ void emergency_remount(void)
 	pdflush_operation(do_emergency_remount, 0);
 }
 
+#ifdef CONFIG_FAST_POWER_OFF
+void suspend_emergency_remount(void)
+{
+	do_emergency_remount(0);
+}
+#endif
 /*
  * Unnamed block devices are dummy devices used by virtual
  * filesystems which don't use real block-devices.  -- jrs

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Re: [PATCH 1/2] PM: fast power off - core

[Andrew Morton]

On Sat, 27 Jan 2007 09:36:53 -1000
akuster <akuster@mvista.com> wrote:

> Fastpoweroff  allows a user to power down the system without using rc kill
> scripts. 

Confused.  I just type `halt -pfn'.  Why is this patch better?

Re: [PATCH 1/2] PM: fast power off - core

[akuster]

Andrew,

Andrew Morton wrote:
> On Sat, 27 Jan 2007 09:36:53 -1000
> akuster <akuster@mvista.com> wrote:
> 
>> Fastpoweroff  allows a user to power down the system without using rc kill
>> scripts. 
> 
> Confused. 

I have a knack of doing that.

  I just type `halt -pfn'.

Thats fine but from what I can tell, it does not try to remount the file 
system before powering off.

  Why is this patch better?

It allows the user to configure how a power off sequence is defined 
beyond the "Halt" via inserting a new profile module. In the default,
processes are frozen and the file system is remounted as read only.

- Armin

Re: [PATCH 1/2] PM: fast power off - core

[Randy Dunlap]

On Sat, 27 Jan 2007 10:05:43 -1000 akuster wrote:

> My apologies, I cc'd the wrong list the first time around.

{argh, attachments}

--- linux-2.6_dev.orig/kernel/power/Kconfig
+++ linux-2.6_dev/kernel/power/Kconfig
@@ -131,3 +131,5 @@ config SUSPEND_SMP
 	bool
 	depends on HOTPLUG_CPU && X86 && PM
 	default y
+
+source "kernel/power/fastoff/Kconfig"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Why a separate, new Kconfig file?
We shouldn't add a new Kconfig file for every new 1-2 kconfig symbols.


---
~Randy

Re: [PATCH 1/2] PM: fast power off - core

[Pavel Machek]

Hi!

> Fastpoweroff  allows a user to power down the system without using rc kill
> scripts. This is used in the advent of a battery operated device about to lose
> power.  The user interface is vis sysfs /sys/power/fastpoweroff. A simple cat of
> the fastpoweroff will list any registered profiles.  To invoke
> the profile sequence, echo {profile name} > /sys/power/fastpoweroff.

No, we do not want "poweroff profiles" in kernel. Sorry.

rc kill scripts should be fast enough, if not, fix them. If it is
impossible (time is spent in kernel waiting for network card to shut
off), fix that.

What you want is pretty much "echo b > ..../sysrq; halt --now".

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 1/2] PM: fast power off - core

[akuster]

Randy Dunlap wrote:
> On Sat, 27 Jan 2007 10:05:43 -1000 akuster wrote:
> 
>> My apologies, I cc'd the wrong list the first time around.
> 
> {argh, attachments}

my bad
> 
> --- linux-2.6_dev.orig/kernel/power/Kconfig
> +++ linux-2.6_dev/kernel/power/Kconfig
> @@ -131,3 +131,5 @@ config SUSPEND_SMP
>  	bool
>  	depends on HOTPLUG_CPU && X86 && PM
>  	default y
> +
> +source "kernel/power/fastoff/Kconfig"
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Why a separate, new Kconfig file?
Thought it would be cleaner.

> We shouldn't add a new Kconfig file for every new 1-2 kconfig symbols.
OK
> 
> 
> ---
> ~Randy

Re: [PATCH 1/2] PM: fast power off - core

[akuster]

Pavel Machek wrote:
> Hi!
> 
>> Fastpoweroff  allows a user to power down the system without using rc kill
>> scripts. This is used in the advent of a battery operated device about to lose
>> power.  The user interface is vis sysfs /sys/power/fastpoweroff. A simple cat of
>> the fastpoweroff will list any registered profiles.  To invoke
>> the profile sequence, echo {profile name} > /sys/power/fastpoweroff.
> 
> No, we do not want "poweroff profiles" in kernel. Sorry.
No need to be.

> 
> rc kill scripts should be fast enough, if not, fix them. If it is
> impossible (time is spent in kernel waiting for network card to shut
> off), fix that.
> 
> What you want is pretty much "echo b > ..../sysrq; halt --now".

The one draw back is that Magic sysrq needs to be enabled and it might 
not be desired in a deployed system.  "echo u " is more of what I was 
looking for.

Thanks for you time.

Armin