power: reset: macsmc-reboot: Prevent probing without of_node

MFD will probe sub devices declared with MFD_CELL_OF() even without
match on the device tree compatible. macsmc-reboot depends on nvmem
provided via device tree. Fail probe() with -ENODEV if this information
is missing.

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

drivers/power/reset/macsmc-reboot.c

@@ -205,6 +205,14 @@ static int macsmc_reboot_probe(struct platform_device *pdev)
 	struct macsmc_reboot *reboot;
 	int ret, i;
 
+	/*
+	 * MFD will probe this device even without a node in the device tree,
+	 * thus bail out early if the SMC on the current machines does not
+	 * support reboot and has no node in the device tree.
+	 */
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
 	reboot = devm_kzalloc(&pdev->dev, sizeof(*reboot), GFP_KERNEL);
 	if (!reboot)
 		return -ENOMEM;