CCM_CCSR
uint32_t ccsr = HREAD4(sc, CCM_CCSR);
HCLR4(sc, CCM_CCSR, CCM_CCSR_PLL1_SW_CLK_SEL);
HCLR4(sc, CCM_CCSR, CCM_CCSR_STEP_SEL);
HCLR4(sc, CCM_CCSR, CCM_CCSR_STEP_SEL);
HSET4(sc, CCM_CCSR, CCM_CCSR_PLL1_SW_CLK_SEL);
HSET4(sc, CCM_CCSR, CCM_CCSR_STEP_SEL);
HSET4(sc, CCM_CCSR, CCM_CCSR_PLL1_SW_CLK_SEL);