[RFC v4 2/3] cpuidle : Add callback whenever a state usage is enabled/disabled

[Abhishek Goel <huntbag@linux.vnet.ibm.com>]

To force wakeup a cpu, we need to compute the timeout in the fast idle
path as a state may be enabled or disabled but there did not exist a
feedback to driver when a state is enabled or disabled.
This patch adds a callback whenever a state_usage records a store for
disable attribute.

Signed-off-by: Abhishek Goel <huntbag@linux.vnet.ibm.com>
---
 drivers/cpuidle/sysfs.c | 15 ++++++++++++++-
 include/linux/cpuidle.h |  4 ++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c
index eb20adb5de23..141671a53967 100644
--- a/drivers/cpuidle/sysfs.c
+++ b/drivers/cpuidle/sysfs.c
@@ -415,8 +415,21 @@ static ssize_t cpuidle_state_store(struct kobject *kobj, struct attribute *attr,
 	struct cpuidle_state_usage *state_usage = kobj_to_state_usage(kobj);
 	struct cpuidle_state_attr *cattr = attr_to_stateattr(attr);
 
-	if (cattr->store)
+	if (cattr->store) {
 		ret = cattr->store(state, state_usage, buf, size);
+		if (ret == size &&
+			strncmp(cattr->attr.name, "disable",
+						strlen("disable"))) {
+			struct kobject *cpuidle_kobj = kobj->parent;
+			struct cpuidle_device *dev =
+					to_cpuidle_device(cpuidle_kobj);
+			struct cpuidle_driver *drv =
+					cpuidle_get_cpu_driver(dev);
+
+			if (drv->disable_callback)
+				drv->disable_callback(dev, drv);
+		}
+	}
 
 	return ret;
 }
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index bb9a0db89f1a..8a0e54bd0d5d 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -119,6 +119,10 @@ struct cpuidle_driver {
 
 	/* the driver handles the cpus in cpumask */
 	struct cpumask		*cpumask;
+
+	void (*disable_callback)(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv);
+
 };
 
 #ifdef CONFIG_CPU_IDLE
-- 
2.17.1