iio:adc:ad799x: Fix reading and writing of event values, apply shift

last two bits of ADC and limit values are zero and should not be reported
(ad7993, ad7997); compare with read_raw()

event values are 10 (ad7993, ad7997) or 12 bit max., check the range on write

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Cc: Stable@vger.kernel.org
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c
index 39b4cb48d738c8f42a6d96beda5152869522d454..6eba301ee03dc04ea4e174a401e99f3e176104c0 100644 (file)
--- a/drivers/iio/adc/ad799x.c
+++ b/drivers/iio/adc/ad799x.c
@@ -427,9 +427,12 @@ static int ad799x_write_event_value(struct iio_dev *indio_dev,
        int ret;
        struct ad799x_state *st = iio_priv(indio_dev);
 
+       if (val < 0 || val > RES_MASK(chan->scan_type.realbits))
+               return -EINVAL;
+
        mutex_lock(&indio_dev->mlock);
        ret = ad799x_i2c_write16(st, ad799x_threshold_reg(chan, dir, info),
-               val);
+               val << chan->scan_type.shift);
        mutex_unlock(&indio_dev->mlock);
 
        return ret;
@@ -452,7 +455,8 @@ static int ad799x_read_event_value(struct iio_dev *indio_dev,
        mutex_unlock(&indio_dev->mlock);
        if (ret < 0)
                return ret;
-       *val = valin;
+       *val = (valin >> chan->scan_type.shift) &
+               RES_MASK(chan->scan_type.realbits);
 
        return IIO_VAL_INT;
 }