/* Set the oscillator source to be used by the system clock. 
USERCC2 must have been set by a call to  */
void rcc_set_osc_source(enum osc_src src)
/* Set the oscillator source to be used by the system clock. 
USERCC2 must have been set by a call to  */
void rcc_set_osc_source(enum osc_src src)
{
	uint32_t reg32;
	reg32 = SYSCTL_RCC2;
	reg32 &= ~SYSCTL_RCC2_OSCSRC2_MASK;
	reg32 |= (src & SYSCTL_RCC2_OSCSRC2_MASK);
	SYSCTL_RCC2 = reg32;
}