power: regulator: denied disable on always-on regulator

Don't disable regulator which are tagged as "regulator-always-on" in DT.
Signed-off-by: NPatrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>
Reviewed-by: NJack Mitchell <jack@embed.me.uk>
Tested-by: NJack Mitchell <jack@embed.me.uk>
Signed-off-by: NPatrice Chotard <patrice.chotard@st.com>
Reviewed-by: NRichard Röjfors <richard@puffinpack.se>
Tested-by: NRichard Röjfors <richard@puffinpack.se>
Reviewed-by: NFelix Brack <fb@ltec.ch>
Tested-by: NFelix Brack <fb@ltec.ch>

drivers/power/regulator/regulator-uclass.c

@@ -106,10 +106,15 @@ int regulator_get_enable(struct udevice *dev)
 int regulator_set_enable(struct udevice *dev, bool enable)
 {
 	const struct dm_regulator_ops *ops = dev_get_driver_ops(dev);
+	struct dm_regulator_uclass_platdata *uc_pdata;
 
 	if (!ops || !ops->set_enable)
 		return -ENOSYS;
 
+	uc_pdata = dev_get_uclass_platdata(dev);
+	if (!enable && uc_pdata->always_on)
+		return -EACCES;
+
 	return ops->set_enable(dev, enable);
 }