[PATCH v3] pm_ops: add system quiesce/activate hooks

[Johannes Berg <johannes@sipsolutions.net>]

For powermac, we need to do some things between suspending devices and
device_power_off, for example setting the decrementer. This patch
introduces pm_ops.quiesce and pm_ops.activate which will be called instead
of disabling/enabling irqs so platforms get control over this step.

If not assigned, these two calls will be assigned with defaults during
set_pm_ops.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

---
This doesn't make sense for suspend to disk since there the arch gets
much more control over the process anyway, and using pm_ops for suspend
to disk is a hack in the first place (only makes sense for ACPI).
Therefore, this patch doesn't affect suspend to disk.

You can now chose either version 2 or 3 of this patch :)

 include/linux/pm.h  |   10 ++++++++++
 kernel/power/main.c |   35 ++++++++++++++++++++++++++++++++---
 2 files changed, 42 insertions(+), 3 deletions(-)

--- wireless-dev.orig/include/linux/pm.h	2007-04-13 09:39:42.465356880 +0200
+++ wireless-dev/include/linux/pm.h	2007-04-13 09:43:42.985356880 +0200
@@ -135,9 +135,17 @@ typedef int __bitwise suspend_disk_metho
  * @prepare: Prepare the platform for the given suspend state. Can return a
  *	negative error code if necessary.
  *
+ * @quiesce: If assigned, this callback must at least turn off IRQs. If
+ *	left unassigned, a default callback that does nothing but turn
+ *	off IRQs is assigned during pm_set_ops().
+ *
  * @enter: Enter the given suspend state, must be assigned. Can return a
  *	negative error code if necessary.
  *
+ * @activate: If assigned, this callback must at least turn on IRQs. If
+ *	left unassigned, a default callback that does nothing but turn
+ *	on IRQs is assigned during pm_set_ops().
+ *
  * @finish: Called when the system has left the given state and all devices
  *	are resumed. The return value is ignored.
  *
@@ -155,7 +163,9 @@ typedef int __bitwise suspend_disk_metho
 struct pm_ops {
 	int (*valid)(suspend_state_t state);
 	int (*prepare)(suspend_state_t state);
+	void (*quiesce)(suspend_state_t state);
 	int (*enter)(suspend_state_t state);
+	void (*activate)(suspend_state_t state);
 	int (*finish)(suspend_state_t state);
 	suspend_disk_method_t pm_disk_mode;
 };
--- wireless-dev.orig/kernel/power/main.c	2007-04-13 09:39:42.465356880 +0200
+++ wireless-dev/kernel/power/main.c	2007-04-13 09:47:38.645356880 +0200
@@ -33,6 +33,28 @@ struct pm_ops *pm_ops;
 suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN;
 
 /**
+ * pm_default_quiesce - default quiesce callback
+ *
+ * pm_ops drivers that need to do nothing but disable IRQs
+ * leave .quiesce unassigned and pm_set_ops() assigns this.
+ */
+static void pm_default_quiesce(suspend_state_t state)
+{
+	local_irq_disable();
+}
+
+/**
+ * pm_default_activate - default activate callback
+ *
+ * pm_ops drivers that need to do nothing but enable IRQs
+ * leave .activate unassigned and pm_set_ops assigns this.
+ */
+static void pm_default_activate(suspend_state_t state)
+{
+	local_irq_enable();
+}
+
+/**
  *	pm_set_ops - Set the global power method table. 
  *	@ops:	Pointer to ops structure.
  */
@@ -45,6 +67,12 @@ void pm_set_ops(struct pm_ops * ops)
 		pm_disk_mode = ops->pm_disk_mode;
 	} else
 		pm_disk_mode = PM_DISK_SHUTDOWN;
+
+	if (!ops->quiesce)
+		ops->quiesce = pm_default_quiesce;
+	if (!ops->activate)
+		ops->activate = pm_default_activate;
+
 	mutex_unlock(&pm_mutex);
 }
 
@@ -132,9 +160,9 @@ static int suspend_prepare(suspend_state
 int suspend_enter(suspend_state_t state)
 {
 	int error = 0;
-	unsigned long flags;
 
-	local_irq_save(flags);
+	pm_ops->quiesce(state);
+	BUG_ON(!irqs_disabled());
 
 	if ((error = device_power_down(PMSG_SUSPEND))) {
 		printk(KERN_ERR "Some devices failed to power down\n");
@@ -143,7 +171,8 @@ int suspend_enter(suspend_state_t state)
 	error = pm_ops->enter(state);
 	device_power_up();
  Done:
-	local_irq_restore(flags);
+	pm_ops->activate(state);
+	BUG_ON(irqs_disabled());
 	return error;
 }