/* configure the PLL clock source selection and PLL multiply factor  */
void rcu_pll_config(uint32_t pll_src, uint32_t pll_mul)
/* configure the PLL clock source selection and PLL multiply factor  */
void rcu_pll_config(uint32_t pll_src, uint32_t pll_mul)
{
    RCU_CFG0 &= ~(RCU_CFG0_PLLSEL | RCU_CFG0_PLLMF);
    RCU_CFG0 |= (pll_src | pll_mul);
}