[PATCH 1/4] power: regulator: Add helper to set voltage within an acceptable range

[Jonas Karlman]

Add regulator_set_value_clamp() that clamps a requested target voltage
to both caller-provided limits and the regulator constraints before
setting the regulator voltage value.

Return -EINVAL when the caller limits cannot be satisfied by the
regulator constraints or when the requested range is invalid.

This helper will initially be used to set vqmmc-supply voltage within an
acceptable range according to SD Standards, i.e. 1.70V-1.95V and
2.7V-3.6V.

Signed-off-by: Jonas Karlman <jonas at kwiboo.se>
---
 drivers/power/regulator/regulator-uclass.c | 27 ++++++++++++++++++++++
 include/power/regulator.h                  | 12 ++++++++++
 2 files changed, 39 insertions(+)

diff --git a/drivers/power/regulator/regulator-uclass.c b/drivers/power/regulator/regulator-uclass.c
index 1c7f75a9338c..0f5ba51ad6c2 100644
--- a/drivers/power/regulator/regulator-uclass.c
+++ b/drivers/power/regulator/regulator-uclass.c
@@ -111,6 +111,33 @@ int regulator_get_suspend_value(struct udevice *dev)
 	return ops->get_suspend_value(dev);
 }
 
+int regulator_set_value_clamp(struct udevice *dev,
+			      int min_uV, int target_uV, int max_uV)
+{
+	const struct dm_regulator_ops *ops = dev_get_driver_ops(dev);
+	struct dm_regulator_uclass_plat *uc_pdata;
+	int uV;
+
+	if (!ops || !ops->set_value)
+		return -ENOSYS;
+
+	uc_pdata = dev_get_uclass_plat(dev);
+	if (uc_pdata->min_uV != -ENODATA && max_uV < uc_pdata->min_uV)
+		return -EINVAL;
+	if (uc_pdata->max_uV != -ENODATA && min_uV > uc_pdata->max_uV)
+		return -EINVAL;
+	if (min_uV > max_uV)
+		return -EINVAL;
+
+	if (uc_pdata->min_uV != -ENODATA)
+		min_uV = max(min_uV, uc_pdata->min_uV);
+	if (uc_pdata->max_uV != -ENODATA)
+		max_uV = min(max_uV, uc_pdata->max_uV);
+	uV = clamp(target_uV, min_uV, max_uV);
+
+	return regulator_set_value(dev, uV);
+}
+
 /*
  * To be called with at most caution as there is no check
  * before setting the actual voltage value.
diff --git a/include/power/regulator.h b/include/power/regulator.h
index 4011fb1d254b..a48bb3a5a1db 100644
--- a/include/power/regulator.h
+++ b/include/power/regulator.h
@@ -315,6 +315,18 @@ int regulator_set_suspend_value(struct udevice *dev, int uV);
  */
 int regulator_get_suspend_value(struct udevice *dev);
 
+/**
+ * regulator_set_value_clamp: set clamped microvoltage value of a given regulator
+ *
+ * @dev       - pointer to the regulator device
+ * @min_uV    - the minimum output value to set [micro Volts]
+ * @target_uV - the target output value to set [micro Volts]
+ * @max_uV    - the maximum output value to set [micro Volts]
+ * Return:    - 0 on success or -errno val if fails
+ */
+int regulator_set_value_clamp(struct udevice *dev,
+			      int min_uV, int target_uV, int max_uV);
+
 /**
  * regulator_set_value_force: set the microvoltage value of a given regulator
  *			      without any min-,max condition check
-- 
2.54.0