apm821xx: detect sd-card media changes for the WNDR4700

The insertion or removal of the sd-card cannot be detected
by the hardware itself. This is by design. To workaround this,
for the WNDR4700 unload/load the dwc2 module in case the
the special SD CARD GPIO line is low/high.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

target/linux/apm821xx/base-files/etc/rc.button/BTN_1

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+. /lib/functions.sh
+. /lib/apm821xx.sh
+
+BOARD=$(apm821xx_board_name)
+
+if [ $BOARD == "wndr4700" ]; then
+	case "$ACTION" in
+	released)
+		rmmod dwc2
+	;;
+	pressed)
+		modprobe dwc2
+	;;
+	esac
+fi
+
+return 0

target/linux/apm821xx/dts/wndr4700.dts

@@ -432,7 +432,7 @@
 
 				sdcard {
 					label = "SDCard inserted";
-					gpios = <&GPIO0 7 0>;
+					gpios = <&GPIO0 7 1>;
 					linux,code = <0x101>; /* BTN_1 */
 				};
 			};