code_to_gain_dB
return st->chip_info->code_to_gain_dB(st->gain, val, val2);
ret = code_to_gain_dB(st, val, val2);
.code_to_gain_dB = hmc425a_code_to_gain_dB,
.code_to_gain_dB = hmc540s_code_to_gain_dB,
.code_to_gain_dB = adrf5740_code_to_gain_dB,
.code_to_gain_dB = ltc6373_code_to_gain_dB,
int (*code_to_gain_dB)(int code, int *val, int *val2);