PM / OPP: Implement of_dev_pm_opp_find_required_opp()

A device's DT node or its OPP nodes can contain a phandle to other
device's OPP node, in the "required-opps" property.

This patch implements a routine to find that required OPP from the node
that contains the "required-opps" property.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index a0f72c732718c2c314e3232f07c0ad20b9c21c6b..416f54ba7a26c70b484d821d0fbd5ece0ecbca34 100644 (file)
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -33,8 +33,6 @@ LIST_HEAD(opp_tables);
 /* Lock to allow exclusive modification to the device and opp lists */
 DEFINE_MUTEX(opp_table_lock);
 
-static void dev_pm_opp_get(struct dev_pm_opp *opp);
-
 static struct opp_device *_find_opp_dev(const struct device *dev,
                                        struct opp_table *opp_table)
 {
@@ -901,7 +899,7 @@ static void _opp_kref_release(struct kref *kref)
        dev_pm_opp_put_opp_table(opp_table);
 }
 
-static void dev_pm_opp_get(struct dev_pm_opp *opp)
+void dev_pm_opp_get(struct dev_pm_opp *opp)
 {
        kref_get(&opp->kref);
 }

diff --git a/drivers/opp/of.c b/drivers/opp/of.c
index cba669cd00c5e8abb7eaffb016c1ec8ace4e1d29..6380ec3d695b913dc2b8f6b9627289664fd8f7fa 100644 (file)
--- a/drivers/opp/of.c
+++ b/drivers/opp/of.c
@@ -673,3 +673,57 @@ put_cpu_node:
        return ret;
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_of_get_sharing_cpus);
+
+/**
+ * of_dev_pm_opp_find_required_opp() - Search for required OPP.
+ * @dev: The device whose OPP node is referenced by the 'np' DT node.
+ * @np: Node that contains the "required-opps" property.
+ *
+ * Returns the OPP of the device 'dev', whose phandle is present in the "np"
+ * node. Although the "required-opps" property supports having multiple
+ * phandles, this helper routine only parses the very first phandle in the list.
+ *
+ * Return: Matching opp, else returns ERR_PTR in case of error and should be
+ * handled using IS_ERR.
+ *
+ * The callers are required to call dev_pm_opp_put() for the returned OPP after
+ * use.
+ */
+struct dev_pm_opp *of_dev_pm_opp_find_required_opp(struct device *dev,
+                                                  struct device_node *np)
+{
+       struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ENODEV);
+       struct device_node *required_np;
+       struct opp_table *opp_table;
+
+       opp_table = _find_opp_table(dev);
+       if (IS_ERR(opp_table))
+               return ERR_CAST(opp_table);
+
+       required_np = of_parse_phandle(np, "required-opps", 0);
+       if (unlikely(!required_np)) {
+               dev_err(dev, "Unable to parse required-opps\n");
+               goto put_opp_table;
+       }
+
+       mutex_lock(&opp_table->lock);
+
+       list_for_each_entry(temp_opp, &opp_table->opp_list, node) {
+               if (temp_opp->available && temp_opp->np == required_np) {
+                       opp = temp_opp;
+
+                       /* Increment the reference count of OPP */
+                       dev_pm_opp_get(opp);
+                       break;
+               }
+       }
+
+       mutex_unlock(&opp_table->lock);
+
+       of_node_put(required_np);
+put_opp_table:
+       dev_pm_opp_put_opp_table(opp_table);
+
+       return opp;
+}
+EXPORT_SYMBOL_GPL(of_dev_pm_opp_find_required_opp);

diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
index 381a4fb15d5c869f122643c694e58ec7a52b07c1..f9eccf9811ae88b99d7094d9b0d140133620e827 100644 (file)
--- a/drivers/opp/opp.h
+++ b/drivers/opp/opp.h
@@ -187,6 +187,7 @@ struct opp_table {
 };
 
 /* Routines internal to opp core */
+void dev_pm_opp_get(struct dev_pm_opp *opp);
 void _get_opp_table_kref(struct opp_table *opp_table);
 int _get_opp_count(struct opp_table *opp_table);
 struct opp_table *_find_opp_table(struct device *dev);

diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index f042fdeaaa3c759aaca1319f7fd7b4f29656c26a..70686f434c133fb7c937f496293c8a8e42c83b13 100644 (file)
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -309,6 +309,7 @@ int dev_pm_opp_of_cpumask_add_table(const struct cpumask *cpumask);
 void dev_pm_opp_of_cpumask_remove_table(const struct cpumask *cpumask);
 int dev_pm_opp_of_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask);
 struct device_node *dev_pm_opp_of_get_opp_desc_node(struct device *dev);
+struct dev_pm_opp *of_dev_pm_opp_find_required_opp(struct device *dev, struct device_node *np);
 #else
 static inline int dev_pm_opp_of_add_table(struct device *dev)
 {
@@ -342,6 +343,11 @@ static inline struct device_node *dev_pm_opp_of_get_opp_desc_node(struct device
 {
        return NULL;
 }
+
+static inline struct dev_pm_opp *of_dev_pm_opp_find_required_opp(struct device *dev, struct device_node *np)
+{
+       return NULL;
+}
 #endif
 
 #endif         /* __LINUX_OPP_H__ */