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@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
Changes
- This patch (1/4 of the set) is resubmitted for the code style revise.
- Added at devfreq patch set v6 replacing devfreq_update calls at OPP.
---
drivers/base/power/opp.c | 29 +++++++++++++++++++++++++++++
include/linux/opp.h | 12 ++++++++++++
2 files changed, 41 insertions(+), 0 deletions(-)
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index b23de18..e6b4c89 100644
--- 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 +659,16 @@ 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
--- 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)
--
1.7.4.1
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