IWP_FH_TCSR_LOWER_BOUND
(IWP_FH_TCSR_LOWER_BOUND + 0x20 * _chnl)
(IWP_FH_TCSR_LOWER_BOUND + 0x20 * _chnl + 0x4)
(IWP_FH_TCSR_LOWER_BOUND + 0x20 * _chnl + 0x8)