[PATCH 13/37] PM: Make PM_TRACE more architecture independent

[Len Brown]

From: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>

When trying to debug a suspend failure I started implementing
PM_TRACE for powerpc. I then noticed that I'm debugging a suspend
failure and so PM_TRACE isn't useful at all, but thought that
nonetheless this could be useful in the future.

Basically, to support PM_TRACE, you add a Kconfig option that
selects PM_TRACE and provides the infrastructure as per the
help text of PM_TRACE.

Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
Signed-off-by: Len Brown <len.brown@xxxxxxxxx>
---
 drivers/base/power/Makefile |    2 +-
 kernel/power/Kconfig        |   23 ++++++++++++++++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index de28dfd..911208b 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -1,6 +1,6 @@
 obj-$(CONFIG_PM)	+= sysfs.o
 obj-$(CONFIG_PM_SLEEP)	+= main.o
-obj-$(CONFIG_PM_TRACE)	+= trace.o
+obj-$(CONFIG_PM_TRACE_RTC)	+= trace.o
 
 ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
 ccflags-$(CONFIG_PM_VERBOSE)   += -DDEBUG
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 8e186c6..06a08f7 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -44,9 +44,30 @@ config PM_VERBOSE
 	---help---
 	This option enables verbose messages from the Power Management code.
 
+config CAN_PM_TRACE
+	def_bool y
+	depends on PM_DEBUG && PM_SLEEP && EXPERIMENTAL
+
 config PM_TRACE
+	bool
+	help
+	  This enables code to save the last PM event point across
+	  reboot. The architecture needs to support this, x86 for
+	  example does by saving things in the RTC, see below.
+
+	  The architecture specific code must provide the extern
+	  functions from <linux/resume-trace.h> as well as the
+	  <asm/resume-trace.h> header with a TRACE_RESUME() macro.
+
+	  The way the information is presented is architecture-
+	  dependent, x86 will print the information during a
+	  late_initcall.
+
+config PM_TRACE_RTC
 	bool "Suspend/resume event tracing"
-	depends on PM_DEBUG && X86 && PM_SLEEP && EXPERIMENTAL
+	depends on CAN_PM_TRACE
+	depends on X86
+	select PM_TRACE
 	default n
 	---help---
 	This enables some cheesy code to save the last PM event point in the
-- 
1.5.4.rc5.16.gc0279

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