staging:iio-trig-periodic-rtc: Allow to reset frequency to 0

periodic rtc trigger initially has frequency 0

it is possible to change trigger frequency on-the-fly, but it is not
possible to set frequency back to 0

this patch allows to set trigger frequency to 0, thereby disabling
the rtc interrupt

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 16 insertions, 3 deletions

diff --git a/drivers/staging/iio/trigger/iio-trig-periodic-rtc.c b/drivers/staging/iio/trigger/iio-trig-periodic-rtc.c
index 362a54a16e58..b5108a163e37 100644
--- a/drivers/staging/iio/trigger/iio-trig-periodic-rtc.c
+++ b/drivers/staging/iio/trigger/iio-trig-periodic-rtc.c
@@ -26,16 +26,22 @@ struct iio_prtc_trigger_info {
         struct rtc_device *rtc;
         int frequency;
         struct rtc_task task;
+        bool state;
 };
 
 static int iio_trig_periodic_rtc_set_state(struct iio_trigger *trig, bool state)
 {
         struct iio_prtc_trigger_info *trig_info = iio_trigger_get_drvdata(trig);
-        if (trig_info->frequency == 0)
+        int ret;
+        if (trig_info->frequency == 0 && state)
                 return -EINVAL;
         dev_dbg(&trig_info->rtc->dev, "trigger frequency is %d\n",
                         trig_info->frequency);
-        return rtc_irq_set_state(trig_info->rtc, &trig_info->task, state);
+        ret = rtc_irq_set_state(trig_info->rtc, &trig_info->task, state);
+        if (ret == 0)
+                trig_info->state = state;
+
+        return ret;
 }
 
 static ssize_t iio_trig_periodic_read_freq(struct device *dev,
@@ -61,7 +67,14 @@ static ssize_t iio_trig_periodic_write_freq(struct device *dev,
         if (ret)
                 goto error_ret;
 
-        ret = rtc_irq_set_freq(trig_info->rtc, &trig_info->task, val);
+        if (val > 0) {
+                ret = rtc_irq_set_freq(trig_info->rtc, &trig_info->task, val);
+                if (ret == 0 && trig_info->state && trig_info->frequency == 0)
+                        ret = rtc_irq_set_state(trig_info->rtc, &trig_info->task, 1);
+        } else if (val == 0) {
+                ret = rtc_irq_set_state(trig_info->rtc, &trig_info->task, 0);
+        } else
+                ret = -EINVAL;
         if (ret)
                 goto error_ret;