SCR_USRC_SEL_OFFSET
#define SCR_USRC_SEL_MASK (0x3 << SCR_USRC_SEL_OFFSET)
#define SCR_USRC_SEL_NONE (0x0 << SCR_USRC_SEL_OFFSET)
#define SCR_USRC_SEL_RECV (0x1 << SCR_USRC_SEL_OFFSET)
#define SCR_USRC_SEL_CHIP (0x3 << SCR_USRC_SEL_OFFSET)