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>

diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index de28dfd..911208b 100644 (file)
--- 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 (file)
--- 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