AR5K_TSF_L32
tsf_lower = ath5k_hw_reg_read(ah, AR5K_TSF_L32);
ath5k_hw_reg_write(ah, tsf64 & 0xffffffff, AR5K_TSF_L32);
tsf_lo = ath5k_hw_reg_read(ah, AR5K_TSF_L32);
ath5k_hw_reg_write(ah, tsf_lo, AR5K_TSF_L32);