PM: Introduce pm_power_off_prepare

Introduce the pm_power_off_prepare() callback that can be registered by the
interested platforms in analogy with pm_idle() and pm_power_off(), used for
preparing the system to power off (needed by ACPI).

This allows us to drop acpi_sysclass and device_acpi that are only defined in
order to register the ACPI power off preparation callback, which is needed by
pm_power_off() registered in a much different way.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index 18987c7f6add..d40e40a9446c 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -100,6 +100,13 @@ struct pid *cad_pid;
 EXPORT_SYMBOL(cad_pid);
 
 /*
+ * If set, this is used for preparing the system to power off.
+ */
+
+void (*pm_power_off_prepare)(void);
+EXPORT_SYMBOL(pm_power_off_prepare);
+
+/*
  *	Notifier list for kernel code which wants to be called
  *	at shutdown. This is used to stop any idling DMA operations
  *	and the like. 
@@ -867,6 +874,8 @@ EXPORT_SYMBOL_GPL(kernel_halt);
 void kernel_power_off(void)
 {
 	kernel_shutdown_prepare(SYSTEM_POWER_OFF);
+	if (pm_power_off_prepare)
+		pm_power_off_prepare();
 	printk(KERN_EMERG "Power down.\n");
 	machine_power_off();
 }