AR5K_USEC_32
sclock = AR5K_REG_SM(sclock, AR5K_USEC_32);
AR5K_REG_WRITE_BITS(ah, AR5K_USEC_5211, AR5K_USEC_32, 1);
AR5K_REG_WRITE_BITS(ah, AR5K_USEC_5211, AR5K_USEC_32, sclock);