Enable supply event forwarding for fixed regulators by registering the
core helper at probe. This allows critical upstream events (currently
REGULATOR_EVENT_UNDER_VOLTAGE) to propagate to consumers of the fixed
regulator, so users like MMC can take emergency action.

No change for regulators without an upstream supply.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/regulator/fixed.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/regulator/fixed.c b/drivers/regulator/fixed.c
index c63d57c5bd27..4d520fc94e05 100644
--- a/drivers/regulator/fixed.c
+++ b/drivers/regulator/fixed.c
@@ -348,6 +348,13 @@ static int reg_fixed_voltage_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	ret = register_regulator_event_forwarding(drvdata->dev);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable supply event forwarding: %pe\n",
+			ERR_PTR(ret));
+		return ret;
+	}
+
 	return 0;
 }
 
-- 
2.47.3