[PATCH v4 04/12] OPP: Add and export helper to update voltage

[Sibi Sankar]

Add and export 'dev_pm_opp_update_voltage' to update the 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 <si...@codeaurora.org>
---

v4:
 * Function description update [Matthias]
 * Drop initialization [Matthias]
 * Drop err message on opp_table get failure

 drivers/opp/core.c     | 51 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/pm_opp.h | 10 +++++++++
 2 files changed, 61 insertions(+)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index cfad09f5dfffa..7f7060079bb28 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -2248,6 +2248,57 @@ int dev_pm_opp_disable(struct device *dev, unsigned long 
freq)
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_disable);
 
+/**
+ * dev_pm_opp_update_voltage() - Update the voltage of an opp
+ * @dev:       device for which we do this operation
+ * @freq:      OPP frequency to update voltage
+ * @u_volt:    voltage requested for this opp
+ *
+ * Update voltage of a disabled opp corresponding to the given frequency.
+ * This is useful only for devices with single power supply.
+ *
+ * Return: 0 if modification was successful or a negative error value.
+ */
+int dev_pm_opp_update_voltage(struct device *dev, unsigned long freq,
+                             unsigned long u_volt)
+{
+       struct opp_table *opp_table;
+       struct dev_pm_opp *opp;
+       unsigned long tol;
+       int ret = 0;
+
+       opp_table = _find_opp_table(dev);
+       if (IS_ERR(opp_table))
+               return PTR_ERR(opp_table);
+
+       opp = dev_pm_opp_find_freq_exact(dev, freq, false);
+       if (IS_ERR(opp)) {
+               ret = PTR_ERR(opp);
+               goto put_table;
+       }
+
+       mutex_lock(&opp_table->lock);
+
+       /* update only if the opp is disabled */
+       if (opp->available) {
+               ret = -EBUSY;
+               goto unlock;
+       }
+
+       tol = u_volt * opp_table->voltage_tolerance_v1 / 100;
+       opp->supplies[0].u_volt_min = u_volt - tol;
+       opp->supplies[0].u_volt = u_volt;
+       opp->supplies[0].u_volt_min = u_volt + tol;
+
+unlock:
+       mutex_unlock(&opp_table->lock);
+       dev_pm_opp_put(opp);
+put_table:
+       dev_pm_opp_put_opp_table(opp_table);
+       return ret;
+}
+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 cfceb02904018..639bc0382ee02 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -134,6 +134,9 @@ 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);
 
@@ -277,6 +280,13 @@ 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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