s2ram: add arch irq disable/enable hooks

After some more discussion this patch replaces it:

From: Johannes Berg <johannes@sipsolutions.net>
Subject: suspend: add arch irq disable/enable hooks

For powermac, we need to do some things between suspending devices and
device_power_off, for example setting the decrementer. This patch
allows architectures to define arch_s2ram_{en,dis}able_irqs in their
asm/suspend.h to have control over this step.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

include/linux/pm.h

@@ -166,6 +166,24 @@ extern struct pm_ops *pm_ops;
 extern int pm_suspend(suspend_state_t state);
 
 
+/**
+ * arch_suspend_disable_irqs - disable IRQs for suspend
+ *
+ * Disables IRQs (in the default case). This is a weak symbol in the common
+ * code and thus allows architectures to override it if more needs to be
+ * done. Not called for suspend to disk.
+ */
+extern void arch_suspend_disable_irqs(void);
+
+/**
+ * arch_suspend_enable_irqs - enable IRQs after suspend
+ *
+ * Enables IRQs (in the default case). This is a weak symbol in the common
+ * code and thus allows architectures to override it if more needs to be
+ * done. Not called for suspend to disk.
+ */
+extern void arch_suspend_enable_irqs(void);
+
 /*
  * Device power management
  */

kernel/power/main.c

@@ -111,13 +111,24 @@ static int suspend_prepare(suspend_state_t state)
 	return error;
 }
 
+/* default implementation */
+void __attribute__ ((weak)) arch_suspend_disable_irqs(void)
+{
+	local_irq_disable();
+}
+
+/* default implementation */
+void __attribute__ ((weak)) arch_suspend_enable_irqs(void)
+{
+	local_irq_enable();
+}
 
 int suspend_enter(suspend_state_t state)
 {
 	int error = 0;
-	unsigned long flags;
 
-	local_irq_save(flags);
+	arch_suspend_disable_irqs();
+	BUG_ON(!irqs_disabled());
 
 	if ((error = device_power_down(PMSG_SUSPEND))) {
 		printk(KERN_ERR "Some devices failed to power down\n");
@@ -126,7 +137,8 @@ int suspend_enter(suspend_state_t state)
 	error = pm_ops->enter(state);
 	device_power_up();
  Done:
-	local_irq_restore(flags);
+	arch_suspend_enable_irqs();
+	BUG_ON(irqs_disabled());
 	return error;
 }