PIN_BIT_ACLKX
bit = PIN_BIT_ACLKX;
set_bit(PIN_BIT_ACLKX, &mcasp->pdir);
set_bit(PIN_BIT_ACLKX, &mcasp->pdir);
clear_bit(PIN_BIT_ACLKX, &mcasp->pdir);
clear_bit(PIN_BIT_ACLKX, &mcasp->pdir);