[PATCH RFC 6/9] OPP: Add and export helper to update voltage

[Sibi Sankar <sibis@xxxxxxxxxxxxxx>]

Add and export 'dev_pm_opp_update_voltage' to find and update voltage
of an opp for a given frequency. This will be useful to update the opps
with voltages read back from firmware.

Signed-off-by: Sibi Sankar <sibis@xxxxxxxxxxxxxx>
---
 drivers/opp/core.c     | 62 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/pm_opp.h | 10 +++++++
 2 files changed, 72 insertions(+)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index addaf7aae9ae..c066cd120a33 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -2090,6 +2090,68 @@ int dev_pm_opp_disable(struct device *dev, unsigned long freq)
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_disable);
 
+static int _opp_update_voltage(struct device *dev, unsigned long freq,
+			       unsigned long u_volt)
+{
+	struct opp_table *opp_table;
+	struct dev_pm_opp *tmp_opp, *opp = ERR_PTR(-ENODEV);
+	int r = 0;
+
+	/* Find the opp_table */
+	opp_table = _find_opp_table(dev);
+	if (IS_ERR(opp_table)) {
+		r = PTR_ERR(opp_table);
+		dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r);
+		return r;
+	}
+
+	mutex_lock(&opp_table->lock);
+
+	/* Do we have the frequency? */
+	list_for_each_entry(tmp_opp, &opp_table->opp_list, node) {
+		if (tmp_opp->rate == freq) {
+			opp = tmp_opp;
+			break;
+		}
+	}
+
+	if (IS_ERR(opp)) {
+		r = PTR_ERR(opp);
+		goto unlock;
+	}
+
+	/* update only if the opp is disabled */
+	if (opp->available)
+		goto unlock;
+
+	opp->supplies[0].u_volt = u_volt;
+
+unlock:
+	mutex_unlock(&opp_table->lock);
+	dev_pm_opp_put_opp_table(opp_table);
+	return r;
+}
+
+/**
+ * dev_pm_opp_update_voltage() - find and update voltage of an opp
+ *				 for a given frequency
+ * @dev:	device for which we do this operation
+ * @freq:	OPP frequency to update voltage
+ * @u_volt:	voltage requested for this opp
+ *
+ * This is useful only for devices with single power supply.
+ *
+ * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
+ * copy operation, returns 0 if no modification was done OR modification was
+ * successful.
+ */
+int dev_pm_opp_update_voltage(struct device *dev, unsigned long freq,
+			      unsigned long u_volt)
+{
+	return _opp_update_voltage(dev, freq, u_volt);
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_update_voltage);
+
 /**
  * dev_pm_opp_register_notifier() - Register OPP notifier for the device
  * @dev:	Device for which notifier needs to be registered
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index d7cb0e65c4f0..58490f6839ce 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -130,6 +130,9 @@ int dev_pm_opp_enable(struct device *dev, unsigned long freq);
 
 int dev_pm_opp_disable(struct device *dev, unsigned long freq);
 
+int dev_pm_opp_update_voltage(struct device *dev, unsigned long freq,
+			      unsigned long u_volt);
+
 int dev_pm_opp_register_notifier(struct device *dev, struct notifier_block *nb);
 int dev_pm_opp_unregister_notifier(struct device *dev, struct notifier_block *nb);
 
@@ -265,6 +268,13 @@ static inline int dev_pm_opp_disable(struct device *dev, unsigned long freq)
 	return 0;
 }
 
+static inline int dev_pm_opp_update_voltage(struct device *dev,
+					    unsigned long freq,
+					    unsigned long u_volt)
+{
+	return 0;
+}
+
 static inline int dev_pm_opp_register_notifier(struct device *dev, struct notifier_block *nb)
 {
 	return -ENOTSUPP;
-- 
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