PM / OPP: Add OPP availability change notifier.

The patch enables to register notifier_block for an OPP-device in order
to get notified for any changes in the availability of OPPs of the
device. For example, if a new OPP is inserted or enable/disable status
of an OPP is changed, the notifier is executed.

This enables the usage of opp_add, opp_enable, and opp_disable to
directly take effect with any connected entities such as cpufreq or
devfreq.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Mike Turquette <mturquette@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index b23de18..434a6c0 100644 (file)
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -73,6 +73,7 @@ struct opp {
  *             RCU usage: nodes are not modified in the list of device_opp,
  *             however addition is possible and is secured by dev_opp_list_lock
  * @dev:       device pointer
+ * @head:      notifier head to notify the OPP availability changes.
  * @opp_list:  list of opps
  *
  * This is an internal data structure maintaining the link to opps attached to
@@ -83,6 +84,7 @@ struct device_opp {
        struct list_head node;
 
        struct device *dev;
+       struct srcu_notifier_head head;
        struct list_head opp_list;
 };
 
@@ -404,6 +406,7 @@ int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
                }
 
                dev_opp->dev = dev;
+               srcu_init_notifier_head(&dev_opp->head);
                INIT_LIST_HEAD(&dev_opp->opp_list);
 
                /* Secure the device list modification */
@@ -428,6 +431,11 @@ int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
        list_add_rcu(&new_opp->node, head);
        mutex_unlock(&dev_opp_list_lock);
 
+       /*
+        * Notify the changes in the availability of the operable
+        * frequency/voltage list.
+        */
+       srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ADD, new_opp);
        return 0;
 }
 
@@ -504,6 +512,14 @@ static int opp_set_availability(struct device *dev, unsigned long freq,
        mutex_unlock(&dev_opp_list_lock);
        synchronize_rcu();
 
+       /* Notify the change of the OPP availability */
+       if (availability_req)
+               srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ENABLE,
+                                        new_opp);
+       else
+               srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_DISABLE,
+                                        new_opp);
+
        /* clean up old opp */
        new_opp = opp;
        goto out;
@@ -643,3 +659,17 @@ void opp_free_cpufreq_table(struct device *dev,
        *table = NULL;
 }
 #endif         /* CONFIG_CPU_FREQ */
+
+/**
+ * opp_get_notifier() - find notifier_head of the device with opp
+ * @dev:       device pointer used to lookup device OPPs.
+ */
+struct srcu_notifier_head *opp_get_notifier(struct device *dev)
+{
+       struct device_opp *dev_opp = find_device_opp(dev);
+
+       if (IS_ERR(dev_opp))
+               return ERR_PTR(PTR_ERR(dev_opp)); /* matching type */
+
+       return &dev_opp->head;
+}

diff --git a/include/linux/opp.h b/include/linux/opp.h
index 7020e97..87a9208 100644 (file)
--- a/include/linux/opp.h
+++ b/include/linux/opp.h
@@ -16,9 +16,14 @@
 
 #include <linux/err.h>
 #include <linux/cpufreq.h>
+#include <linux/notifier.h>
 
 struct opp;
 
+enum opp_event {
+       OPP_EVENT_ADD, OPP_EVENT_ENABLE, OPP_EVENT_DISABLE,
+};
+
 #if defined(CONFIG_PM_OPP)
 
 unsigned long opp_get_voltage(struct opp *opp);
@@ -40,6 +45,8 @@ int opp_enable(struct device *dev, unsigned long freq);
 
 int opp_disable(struct device *dev, unsigned long freq);
 
+struct srcu_notifier_head *opp_get_notifier(struct device *dev);
+
 #else
 static inline unsigned long opp_get_voltage(struct opp *opp)
 {
@@ -89,6 +96,11 @@ static inline int opp_disable(struct device *dev, unsigned long freq)
 {
        return 0;
 }
+
+struct srcu_notifier_head *opp_get_notifier(struct device *dev)
+{
+       return ERR_PTR(-EINVAL);
+}
 #endif         /* CONFIG_PM */
 
 #if defined(CONFIG_CPU_FREQ) && defined(CONFIG_PM_OPP)