regulator: Allow for asymmetric settling times

Some regulators have different settling times for voltage increases and
decreases. To avoid a time penalty on the faster transition allow for
different settings for up- and downward transitions.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/regulator/of_regulator.c b/drivers/regulator/of_regulator.c
index 09d677d..96bf754 100644
--- a/drivers/regulator/of_regulator.c
+++ b/drivers/regulator/of_regulator.c
@@ -90,6 +90,25 @@ static void of_get_regulation_constraints(struct device_node *np,
 	if (!ret)
 		constraints->settling_time = pval;
 
+	ret = of_property_read_u32(np, "regulator-settling-time-up-us", &pval);
+	if (!ret)
+		constraints->settling_time_up = pval;
+	if (constraints->settling_time_up && constraints->settling_time) {
+		pr_warn("%s: ambiguous configuration for settling time, ignoring 'regulator-settling-time-up-us'\n",
+			np->name);
+		constraints->settling_time_up = 0;
+	}
+
+	ret = of_property_read_u32(np, "regulator-settling-time-down-us",
+				   &pval);
+	if (!ret)
+		constraints->settling_time_down = pval;
+	if (constraints->settling_time_down && constraints->settling_time) {
+		pr_warn("%s: ambiguous configuration for settling time, ignoring 'regulator-settling-time-down-us'\n",
+			np->name);
+		constraints->settling_time_down = 0;
+	}
+
 	ret = of_property_read_u32(np, "regulator-enable-ramp-delay", &pval);
 	if (!ret)
 		constraints->enable_time = pval;