Necessary header file required for using CC2538 Sleep Mode timer

Dear TI Engineers,

 I am using CC2538 (EM) over SmartRF06 Evaluation Board (EB).  I just had the following doubt.

To use the following functions, which header file/s do I need to include in my program since I am getting the 'undefined reference to' error for these functions:

IntEnable(INT_SMTIM); 

// Set timer to 1000 above current value 

ui32Val = SleepModeTimerCountGet(); 

SleepModeTimerCompareSet(ui32Val + 15); 

SysCtrlSleep();

Thanking you,

Indrajit