PM: add kconfig option for deprecated .../power/state files

Add a new PM_SYSFS_DEPRECATED config option to control whether or
not the /sys/devices/.../power/state files are provided.  This will
make it easier to get rid of that mechanism when the time comes,
and to verify that userspace tools work right without it.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 17 insertions, 0 deletions

diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index e55b3c2779e9..2d47517dbe32 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -7,6 +7,8 @@
 #include "power.h"
 
 
+#ifdef  CONFIG_PM_SYSFS_DEPRECATED
+
 /**
  *      state - Control current power state of device
  *
@@ -66,6 +68,8 @@ static ssize_t state_store(struct device * dev, struct device_attribute *attr, c
 static DEVICE_ATTR(state, 0644, state_show, state_store);
 
 
+#endif  /* CONFIG_PM_SYSFS_DEPRECATED */
+
 /*
  *      wakeup - Report/change current wakeup option for device
  *
@@ -139,7 +143,9 @@ static DEVICE_ATTR(wakeup, 0644, wake_show, wake_store);
 
 
 static struct attribute * power_attrs[] = {
+#ifdef  CONFIG_PM_SYSFS_DEPRECATED
         &dev_attr_state.attr,
+#endif
         &dev_attr_wakeup.attr,
         NULL,
 };
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 619ecabf7c58..1ed972070d19 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -53,6 +53,17 @@ config PM_TRACE
         CAUTION: this option will cause your machine's real-time clock to be
         set to an invalid time after a resume.
 
+config PM_SYSFS_DEPRECATED
+        bool "Driver model /sys/devices/.../power/state files (DEPRECATED)"
+        depends on PM && SYSFS
+        default n
+        help
+          The driver model started out with a sysfs file intended to provide
+          a userspace hook for device power management.  This feature has never
+          worked very well, except for limited testing purposes, and so it will
+          be removed.   It's not clear that a generic mechanism could really
+          handle the wide variability of device power states; any replacements
+          are likely to be bus or driver specific.
 
 config SOFTWARE_SUSPEND
         bool "Software Suspend"