sysctl: add boot_reason and cold_boot sysctl entries for arm64

Define boot_reason and cold_boot variables in the arm64 version
of setup.c so that arm64 targets can export the boot_reason and
cold_boot sysctl entries.

This feature is required by the qpnp-power-on driver.

Change-Id: Id2d4ff5b8caa2e6a35d4ac61e338963d602c8b84
Signed-off-by: David Collins <collinsd@codeaurora.org>

Documentation/sysctl/kernel.txt

@@ -23,10 +23,10 @@ show up in /proc/sys/kernel:
 - auto_msgmni
 - bootloader_type	     [ X86 only ]
 - bootloader_version	     [ X86 only ]
-- boot_reason		     [ ARM only ]
+- boot_reason		     [ ARM and ARM64 only ]
 - callhome		     [ S390 only ]
 - cap_last_cap
-- cold_boot		     [ ARM only ]
+- cold_boot		     [ ARM and ARM64 only ]
 - core_pattern
 - core_pipe_limit
 - core_uses_pid
@@ -172,7 +172,7 @@ Documentation/x86/boot.txt for additional information.
 
 boot_reason:
 
-ARM -- reason for device boot
+ARM and ARM64 -- 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
@@ -208,7 +208,7 @@ CAP_LAST_CAP from the kernel.
 
 cold_boot
 
-ARM -- indicator for system cold boot
+ARM and ARM64 -- 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

arch/arm64/include/asm/processor.h

@@ -76,6 +76,9 @@
 extern phys_addr_t arm64_dma_phys_limit;
 #define ARCH_LOW_ADDRESS_LIMIT	(arm64_dma_phys_limit - 1)
 
+extern unsigned int boot_reason;
+extern unsigned int cold_boot;
+
 struct debug_info {
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 	/* Have we suspended stepping by a debugger? */

arch/arm64/kernel/setup.c

@@ -69,6 +69,12 @@ static struct resource *standard_resources;
 
 phys_addr_t __fdt_pointer __initdata;
 
+unsigned int boot_reason;
+EXPORT_SYMBOL(boot_reason);
+
+unsigned int cold_boot;
+EXPORT_SYMBOL(cold_boot);
+
 /*
  * Standard memory resources
  */

kernel/sysctl.c

@@ -1234,7 +1234,7 @@ static struct ctl_table kern_table[] = {
 		.extra2		= &one,
 	},
 #endif
-#ifdef CONFIG_ARM
+#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
 	{
 		.procname	= "boot_reason",
 		.data		= &boot_reason,