Sorry for the late reply.
I understand that Pin 37 should be configured as wake-up source by default. What do you mean by ‘externally’ here? do you mean that “I should try wake-up with some hard key connected to that PIN 37?”
Externally means that you have change the state of the pin by a signal which is not provided by the module. Anyway during suspend mode module (SOC) is inactive, so it cannot active itself, except you put a timer for suspend as explained here.
I don’t see this pin (GPIO 4) under sysfs entry
What is the SODIMM Pin you are looking for? Please note that not all the GPIOs are exported in Linux. Consult this page to get further Information about GPIOs in Linux?
Do i need to configure direction of this pin explicitly ?
No, keep it as GPIO, then it will an input and 0 state. You can control the direction in Linux.