[PATCH V2 2/5] OPP: Add dev_pm_opp_xlate_performance_state() helper

[Viresh Kumar]

Introduce a new helper dev_pm_opp_xlate_performance_state() which will
be used to translate from pstate of a device to another one.

Initially this will be used by genpd to find pstate of a master domain
using its sub-domain's pstate.

Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
 drivers/opp/core.c     | 59 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/pm_opp.h |  7 +++++
 2 files changed, 66 insertions(+)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 0eaa954b3f6c..99b71f60b6d8 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1707,6 +1707,65 @@ void dev_pm_opp_put_genpd_virt_dev(struct opp_table *opp_table,
 		dev_err(virt_dev, "Failed to find required device entry\n");
 }
 
+/**
+ * dev_pm_opp_xlate_performance_state() - Find required OPP's pstate for src_table.
+ * @src_table: OPP table which has dst_table as one of its required OPP table.
+ * @dst_table: Required OPP table of the src_table.
+ * @pstate: Current performance state of the src_table.
+ *
+ * This Returns pstate of the OPP (present in @dst_table) pointed out by the
+ * "required-opps" property of the OPP (present in @src_table) which has
+ * performance state set to @pstate.
+ *
+ * Return: Positive performance state on success, otherwise 0 on errors.
+ */
+unsigned int dev_pm_opp_xlate_performance_state(struct opp_table *src_table,
+						struct opp_table *dst_table,
+						unsigned int pstate)
+{
+	struct dev_pm_opp *opp;
+	unsigned int dest_pstate = 0;
+	int i;
+
+	/*
+	 * Normally the src_table will have the "required_opps" property set to
+	 * point to one of the OPPs in the dst_table, but in some cases the
+	 * genpd and its master have one to one mapping of performance states
+	 * and so none of them have the "required-opps" property set. Return the
+	 * pstate of the src_table as it is in such cases.
+	 */
+	if (!src_table->required_opp_count)
+		return pstate;
+
+	for (i = 0; i < src_table->required_opp_count; i++) {
+		if (src_table->required_opp_tables[i]->np == dst_table->np)
+			break;
+	}
+
+	if (unlikely(i == src_table->required_opp_count)) {
+		pr_err("%s: Couldn't find matching OPP table (%p: %p)\n",
+		       __func__, src_table, dst_table);
+		return 0;
+	}
+
+	mutex_lock(&src_table->lock);
+
+	list_for_each_entry(opp, &src_table->opp_list, node) {
+		if (opp->pstate == pstate) {
+			dest_pstate = opp->required_opps[i]->pstate;
+			goto unlock;
+		}
+	}
+
+	pr_err("%s: Couldn't find matching OPP (%p: %p)\n", __func__, src_table,
+	       dst_table);
+
+unlock:
+	mutex_unlock(&src_table->lock);
+
+	return dest_pstate;
+}
+
 /**
  * dev_pm_opp_add()  - Add an OPP table from a table definitions
  * @dev:	device for which we do this operation
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index 2b2c3fd985ab..5a64a81a1789 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -128,6 +128,7 @@ struct opp_table *dev_pm_opp_register_set_opp_helper(struct device *dev, int (*s
 void dev_pm_opp_unregister_set_opp_helper(struct opp_table *opp_table);
 struct opp_table *dev_pm_opp_set_genpd_virt_dev(struct device *dev, struct device *virt_dev, int index);
 void dev_pm_opp_put_genpd_virt_dev(struct opp_table *opp_table, struct device *virt_dev);
+unsigned int dev_pm_opp_xlate_performance_state(struct opp_table *src_table, struct opp_table *dst_table, unsigned int pstate);
 int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq);
 int dev_pm_opp_set_sharing_cpus(struct device *cpu_dev, const struct cpumask *cpumask);
 int dev_pm_opp_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask);
@@ -280,6 +281,12 @@ static inline struct opp_table *dev_pm_opp_set_genpd_virt_dev(struct device *dev
 }
 
 static inline void dev_pm_opp_put_genpd_virt_dev(struct opp_table *opp_table, struct device *virt_dev) {}
+
+static inline unsigned int dev_pm_opp_xlate_performance_state(struct opp_table *src_table, struct opp_table *dst_table, unsigned int pstate)
+{
+	return 0;
+}
+
 static inline int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 {
 	return -ENOTSUPP;
-- 
2.19.1.568.g152ad8e3369a