gpio: max732x: fix input configuration for open-drain pins

Fix a bug I noticed while hacking on the max732x driver for interrupt
support.  According to the datasheets, open-drain pins have to be
configured as output-high (which in that case is actually high impedance)
to be used as input.

Signed-off-by: Marc Zyngier <maz@misterjones.org>
Acked-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/gpio/max732x.c

@@ -232,6 +232,13 @@ static int max732x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
 		return -EACCES;
 	}
 
+	/*
+	 * Open-drain pins must be set to high impedance (which is
+	 * equivalent to output-high) to be turned into an input.
+	 */
+	if ((mask & chip->dir_output))
+		max732x_gpio_set_value(gc, off, 1);
+
 	return 0;
 }