msm: 8x55: put reason for boot in procfs from SMEM

During board initialization read the shared memory item
SMEM_POWER_ON_STATUS_INFO and place it in the procfs at
/proc/sys/kernel/boot_reason

The data item is an integer with a bit being set to identify the reason
the device was powered on. The values of this data item is defined in
the document Document/arm/msm/boot.txt, the following is the data in the
documentation file.

power_on_status values set by the PMIC for power on event:
----------------------------------------------------------
0x01 -- keyboard power on
0x02 -- RTC alarm
0x04 -- cable power on
0x08 -- SMPL
0x10 -- Watch Dog timeout
0x20 -- USB charger
0x40 -- Wall charger
0xFF -- error reading power_on_status value

Change-Id: I59e665f92e6e29f7dfef4380314f676a2d92c94b
Signed-off-by: Rick Adams <rgadams@codeaurora.org>

Documentation/arm/msm/boot.txt

@@ -0,0 +1,23 @@
+Introduction
+=============
+The power management integrated circuit (PMIC) records the reason the
+Application processor was powered on in Shared Memory.
+The hardware and software used is the shared memory interface. This document
+is not for the purpose of describing this interface, but to identify the
+possible values for this data item.
+
+Description
+===========
+Shared memory item (SMEM_POWER_ON_STATUS_INFO) is read to get access to
+this data. The table below identifies the possible values stored.
+
+power_on_status values set by the PMIC for power on event:
+----------------------------------------------------------
+0x01 -- keyboard power on
+0x02 -- RTC alarm
+0x04 -- cable power on
+0x08 -- SMPL
+0x10 -- Watch Dog timeout
+0x20 -- USB charger
+0x40 -- Wall charger
+0xFF -- error reading power_on_status value

Documentation/sysctl/kernel.txt

@@ -23,6 +23,7 @@ show up in /proc/sys/kernel:
 - auto_msgmni
 - bootloader_type	     [ X86 only ]
 - bootloader_version	     [ X86 only ]
+- boot_reason		     [ ARM only ]
 - callhome		     [ S390 only ]
 - cap_last_cap
 - core_pattern
@@ -168,6 +169,20 @@ Documentation/x86/boot.txt for additional information.
 
 ==============================================================
 
+boot_reason:
+
+ARM -- reason for device boot
+
+A single bit will be set in the unsigned integer value to identify the
+reason the device was booted / powered on. The value will be zero if this
+feature is not supported on the ARM device being booted.
+
+See the power-on-status field definitions in
+Documentation/arm/msm/boot.txt for Qualcomm Technologies, Inc. family of
+devices.
+
+==============================================================
+
 callhome:
 
 Controls the kernel's callhome behavior in case of a kernel panic.

arch/arm/include/asm/processor.h

@@ -30,6 +30,8 @@
 #define STACK_TOP_MAX	TASK_SIZE
 #endif
 
+extern unsigned int boot_reason;
+
 struct debug_info {
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 	struct perf_event	*hbp[ARM_MAX_HBP_SLOTS];

arch/arm/kernel/setup.c

@@ -116,6 +116,9 @@ EXPORT_SYMBOL(elf_hwcap2);
 char* (*arch_read_hardware_id)(void);
 EXPORT_SYMBOL(arch_read_hardware_id);
 
+unsigned int boot_reason;
+EXPORT_SYMBOL(boot_reason);
+
 #ifdef MULTI_CPU
 struct processor processor __ro_after_init;
 #endif

include/uapi/linux/sysctl.h

@@ -153,6 +153,7 @@ enum
 	KERN_NMI_WATCHDOG=75, /* int: enable/disable nmi watchdog */
 	KERN_PANIC_ON_NMI=76, /* int: whether we will panic on an unrecovered */
 	KERN_PANIC_ON_WARN=77, /* int: call panic() in WARN() functions */
+	KERN_BOOT_REASON=78, /* int: identify reason system was booted */
 };
 
 

kernel/sysctl.c

@@ -1233,6 +1233,15 @@ static struct ctl_table kern_table[] = {
 		.extra1		= &zero,
 		.extra2		= &one,
 	},
+#endif
+#ifdef CONFIG_ARM
+	{
+		.procname	= "boot_reason",
+		.data		= &boot_reason,
+		.maxlen		= sizeof(int),
+		.mode		= 0444,
+		.proc_handler	= proc_dointvec,
+},
 #endif
 	{ }
 };

kernel/sysctl_binary.c

@@ -140,6 +140,7 @@ 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_PANIC_ON_WARN,		"panic_on_warn" },
+	{ CTL_INT,	KERN_BOOT_REASON,		"boot_reason" },
 	{}
 };