PM: Make PM_TRACE more architecture independent

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@sipsolutions.net>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 23 insertions, 2 deletions

diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index de28dfd3b96c..911208b89259 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 8e186c678149..06a08f7cebda 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