GL-X750 - Spitz - right RTC chip for the router

there is a placeholder on the board for a RTC chip but which one is the right one?
If i addon the correct RTC, then it usable or i need additional software?

RTC and bluetooth share GPIO1, do you have bluetooth on your device?
Additional packages need to be installed to use RTC.

For SD2068, please excute following command:

opkg update
opkg install kmod-i2c-gpio-custom
opkg install kmod-rtc-sd2068
insmod /lib/modules/3.18.29/i2c-gpio-custom.ko bus0=0,1,17
echo sd2068 0x32 > /sys/bus/i2c/devices/i2c-0/new_device

Note that GPIO1 is held by default by bluetooth, and you need to recompile the firmware and add the following patches before using it

--- a/target/linux/ar71xx/files/arch/mips/ath79/mach-gl-x750.c
+++ b/target/linux/ar71xx/files/arch/mips/ath79/mach-gl-x750.c
@@ -164,9 +164,9 @@ static void __init gl_x750_setup(void)
                          GPIOF_OUT_INIT_LOW | GPIOF_EXPORT_DIR_FIXED,
                          "PCI power");
-        gpio_request_one(GL_X750_GPIO_BLE_RST,
+        /*gpio_request_one(GL_X750_GPIO_BLE_RST,
                          GPIOF_OUT_INIT_LOW | GPIOF_EXPORT_DIR_FIXED,
-                         "BLE RST");
+                         "BLE RST");*/
 //     platform_device_register(&gl_x750_i2c_gpio);