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>

3 files changed, 19 insertions, 29 deletions

diff --git a/drivers/acpi/sleep/poweroff.c b/drivers/acpi/sleep/poweroff.c
index 240dde9cf13a..39e40d56b034 100644
--- a/drivers/acpi/sleep/poweroff.c
+++ b/drivers/acpi/sleep/poweroff.c
@@ -39,7 +39,13 @@ int acpi_sleep_prepare(u32 acpi_state)
 
 #ifdef CONFIG_PM
 
-void acpi_power_off(void)
+static void acpi_power_off_prepare(void)
+{
+        /* Prepare to power off the system */
+        acpi_sleep_prepare(ACPI_STATE_S5);
+}
+
+static void acpi_power_off(void)
 {
         /* acpi_sleep_prepare(ACPI_STATE_S5) should have already been called */
         printk("%s called\n", __FUNCTION__);
@@ -48,27 +54,6 @@ void acpi_power_off(void)
         acpi_enter_sleep_state(ACPI_STATE_S5);
 }
 
-static int acpi_shutdown(struct sys_device *x)
-{
-        switch (system_state) {
-        case SYSTEM_POWER_OFF:
-                /* Prepare to power off the system */
-                return acpi_sleep_prepare(ACPI_STATE_S5);
-        default:
-                return 0;
-        }
-}
-
-static struct sysdev_class acpi_sysclass = {
-        set_kset_name("acpi"),
-        .shutdown = acpi_shutdown
-};
-
-static struct sys_device device_acpi = {
-        .id = 0,
-        .cls = &acpi_sysclass,
-};
-
 static int acpi_poweroff_init(void)
 {
         if (!acpi_disabled) {
@@ -78,13 +63,8 @@ static int acpi_poweroff_init(void)
                 status =
                     acpi_get_sleep_type_data(ACPI_STATE_S5, &type_a, &type_b);
                 if (ACPI_SUCCESS(status)) {
-                        int error;
-                        error = sysdev_class_register(&acpi_sysclass);
-                        if (!error)
-                                error = sysdev_register(&device_acpi);
-                        if (!error)
-                                pm_power_off = acpi_power_off;
-                        return error;
+                        pm_power_off_prepare = acpi_power_off_prepare;
+                        pm_power_off = acpi_power_off;
                 }
         }
         return 0;
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 2735b7cadd20..ad3cc2eb0d34 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -101,6 +101,7 @@ struct pm_dev
  */
 extern void (*pm_idle)(void);
 extern void (*pm_power_off)(void);
+extern void (*pm_power_off_prepare)(void);
 
 typedef int __bitwise suspend_state_t;
 
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();
 }