{
        struct iio_prtc_trigger_info *trig_info = iio_trigger_get_drvdata(trig);
        int ret;
+
        if (trig_info->frequency == 0 && state)
                return -EINVAL;
        dev_dbg(&trig_info->rtc->dev, "trigger frequency is %d\n",
 {
        struct iio_trigger *trig = to_iio_trigger(dev);
        struct iio_prtc_trigger_info *trig_info = iio_trigger_get_drvdata(trig);
+
        return sprintf(buf, "%u\n", trig_info->frequency);
 }
 
 {
        struct iio_trigger *trig, *trig2;
        struct iio_prtc_trigger_info *trig_info;
+
        mutex_lock(&iio_prtc_trigger_list_lock);
        list_for_each_entry_safe(trig,
                                 trig2,