According to Timur Tabi

    This bug in older U-Boots is definitely PowerPC-specific

So before allowing this driver to be built for platforms other than
PPC32, make sure that we don't accept malformed device trees on those
other platforms.

Suggested-by: Timur Tabi <timur@kernel.org>
Reviewed-by: Timur Tabi <timur@kernel.org>
Acked-by: Timur Tabi <timur@kernel.org>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/tty/serial/ucc_uart.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/tty/serial/ucc_uart.c b/drivers/tty/serial/ucc_uart.c
index c055abf4c919..9436b93d5cfa 100644
--- a/drivers/tty/serial/ucc_uart.c
+++ b/drivers/tty/serial/ucc_uart.c

@@ -1392,6 +1392,13 @@ static int ucc_uart_probe(struct platform_device *ofdev)
 	if (val)
 		qe_port->port.uartclk = val;
 	else {
+		if (!IS_ENABLED(CONFIG_PPC32)) {
+			dev_err(&ofdev->dev,
+				"invalid brg-frequency in device tree\n");
+			ret = -EINVAL;
+			goto out_np;
+		}
+
 		/*
 		 * Older versions of U-Boot do not initialize the brg-frequency
 		 * property, so in this case we assume the BRG frequency is

-- 
2.23.0