drivers: regulator: do not cache voltage level value

Always read current voltage level from the device instead of
caching the level in struct regulator. This fixes issues for
when the regulator level value depends on the parent regulator
(supply). It is up the regulator driver to cache or not this
value in their private data if applicable.

Fixes: 1a3d327 ("drivers: regulator framework")
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>

core/drivers/regulator/regulator.c

@@ -181,17 +181,36 @@ bool regulator_is_enabled(struct regulator *regulator)
 	return !res && enabled;
 }
 
+int regulator_get_voltage(struct regulator *regulator)
+{
+	TEE_Result res = TEE_SUCCESS;
+	int level_uv = regulator->min_uv;
+
+	if (regulator->ops->get_voltage) {
+		res = regulator->ops->get_voltage(regulator, &level_uv);
+		if (res) {
+			EMSG("%s get_voltage failed with %#"PRIx32,
+			     regulator_name(regulator), res);
+			level_uv = 0;
+		}
+	}
+
+	return level_uv;
+}
+
 TEE_Result regulator_set_voltage(struct regulator *regulator, int level_uv)
 {
 	TEE_Result res = TEE_ERROR_GENERIC;
+	int cur_uv = 0;
 
 	assert(regulator);
 	FMSG("%s %duV", regulator_name(regulator), level_uv);
 
 	if (level_uv < regulator->min_uv || level_uv > regulator->max_uv)
 		return TEE_ERROR_BAD_PARAMETERS;
 
-	if (level_uv == regulator->cur_uv)
+	cur_uv = regulator_get_voltage(regulator);
+	if (level_uv == cur_uv)
 		return TEE_SUCCESS;
 
 	if (!regulator->ops->set_voltage)
@@ -207,8 +226,6 @@ TEE_Result regulator_set_voltage(struct regulator *regulator, int level_uv)
 		return res;
 	}
 
-	regulator->cur_uv = level_uv;
-
 	return TEE_SUCCESS;
 }
 
@@ -256,14 +273,7 @@ TEE_Result regulator_register(struct regulator *regulator)
 		return TEE_ERROR_BAD_PARAMETERS;
 
 	/* Sanitize regulator effective level */
-	if (regulator->ops->get_voltage) {
-		res = regulator->ops->get_voltage(regulator, &uv);
-		if (res)
-			return res;
-	} else {
-		uv = min_uv;
-	}
-	regulator->cur_uv = uv;
+	uv = regulator_get_voltage(regulator);
 
 	if (uv < min_uv || uv > max_uv) {
 		res = regulator_set_voltage(regulator, min_uv);

core/include/drivers/regulator.h

@@ -85,7 +85,6 @@ struct regulator_voltages_desc {
  * @name: Regulator string name for debug purpose or NULL
  * @min_uv: Min possible voltage level in microvolt (uV)
  * @max_uv: Max possible voltage level in microvolt (uV)
- * @cur_uv: Current voltage level in microvolt (uV)
  * @flags: REGULATOR_* property flags
  * @refcount: Regulator enable request reference counter
  * @lock: Mutex for concurrent access protection
@@ -101,7 +100,6 @@ struct regulator {
 	int min_uv;
 	int max_uv;
 	/* Fields internal to regulator framework */
-	int cur_uv;
 	unsigned int flags;
 	unsigned int refcount;
 	struct mutex lock;	/* Concurrent access protection */
@@ -283,13 +281,10 @@ static inline TEE_Result regulator_set_min_voltage(struct regulator *regulator)
 }
 
 /*
- * regulator_get_voltage() - Get regulator current level in microvolt
+ * regulator_get_voltage() - Get regulator effective voltage level in microvolt
  * @regulator: Regulator reference
  */
-static inline int regulator_get_voltage(struct regulator *regulator)
-{
-	return regulator->cur_uv;
-}
+int regulator_get_voltage(struct regulator *regulator);
 
 /*
  * regulator_get_range() - Get regulator min and/or max support levels