From 8ae67affddec6a2bafc4c3a8714180f356b4ca73 Mon Sep 17 00:00:00 2001
From: David Keitel <dkeitel@codeaurora.org>
Date: Tue, 26 Mar 2013 18:50:03 -0700
Subject: [PATCH] sysctl: add cold_boot sysctl entry

Add a cold_boot parameter which supplements the
boot_reason sysctl entry with information about
whether the system was booted from cold or warm state.

/proc/sys/kernel/cold_boot entry is updated with 1 or 0 when
system was booted from cold or warm boot state respecitively.

CRs-Fixed: 461256
Change-Id: I2bc5d80c8f26eb9e9dbb4b34960d991a51a224e4
Signed-off-by: David Keitel <dkeitel@codeaurora.org>
---
 Documentation/sysctl/kernel.txt  | 11 +++++++++++
 arch/arm/include/asm/processor.h |  1 +
 arch/arm/kernel/setup.c          |  3 +++
 include/linux/sysctl.h           |  1 +
 kernel/sysctl.c                  | 10 +++++++++-
 kernel/sysctl_binary.c           |  1 +
 6 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index a419f5e3143..8a20b4786e8 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -26,6 +26,7 @@ show up in /proc/sys/kernel:
 - boot_reason		     [ ARM only ]
 - callhome		     [ S390 only ]
 - cap_last_cap
+- cold_boot		     [ ARM only ]
 - core_pattern
 - core_pipe_limit
 - core_uses_pid
@@ -176,6 +177,16 @@ cap_last_cap
 Highest valid capability of the running kernel.  Exports
 CAP_LAST_CAP from the kernel.
 
+===============================================================
+
+cold_boot
+
+ARM -- indicator for system cold boot
+
+A single bit will be set in the unsigned integer value to identify
+whether the device was booted from a cold or warm state. Zero
+indicating a warm boot and one indicating a cold boot.
+
 ==============================================================
 
 core_pattern:
diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
index 07209d7538b..3a2cd22504e 100644
--- a/arch/arm/include/asm/processor.h
+++ b/arch/arm/include/asm/processor.h
@@ -30,6 +30,7 @@
 #endif
 
 extern unsigned int boot_reason;
+extern unsigned int cold_boot;
 
 struct debug_info {
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 28b114fc406..7298f9ae694 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -107,6 +107,9 @@ EXPORT_SYMBOL(elf_hwcap);
 unsigned int boot_reason;
 EXPORT_SYMBOL(boot_reason);
 
+unsigned int cold_boot;
+EXPORT_SYMBOL(cold_boot);
+
 #ifdef MULTI_CPU
 struct processor processor __read_mostly;
 #endif
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 84c59dc43e4..d950b5c9dd0 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -154,6 +154,7 @@ enum
 	KERN_NMI_WATCHDOG=75, /* int: enable/disable nmi watchdog */
 	KERN_PANIC_ON_NMI=76, /* int: whether we will panic on an unrecovered */
 	KERN_BOOT_REASON = 77, /* int: identify reason system was booted */
+	KERN_COLD_BOOT = 78, /* int: identify if system cold booted */
 };
 
 
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index b390dadc52c..d16a59ec644 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1009,7 +1009,15 @@ static struct ctl_table kern_table[] = {
 		.maxlen		= sizeof(int),
 		.mode		= 0444,
 		.proc_handler	= proc_dointvec,
-},
+	},
+
+	{
+		.procname	= "cold_boot",
+		.data		= &cold_boot,
+		.maxlen		= sizeof(int),
+		.mode		= 0444,
+		.proc_handler	= proc_dointvec,
+	},
 #endif
 /*
  * NOTE: do not add new entries to this table unless you have read
diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index acb60bef99f..6170f456096 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -138,6 +138,7 @@ static const struct bin_table bin_kern_table[] = {
 	{ CTL_INT,	KERN_MAX_LOCK_DEPTH,		"max_lock_depth" },
 	{ CTL_INT,	KERN_PANIC_ON_NMI,		"panic_on_unrecovered_nmi" },
 	{ CTL_INT,	KERN_BOOT_REASON,		"boot_reason" },
+	{ CTL_INT,	KERN_COLD_BOOT,			"cold_boot" },
 	{}
 };