iio: dac: cio-dac: Fix max DAC write value check for 12-bit

The CIO-DAC series of devices only supports DAC values up to 12-bit
rather than 16-bit. Trying to write a 16-bit value results in only the
lower 12 bits affecting the DAC output which is not what the user
expects. Instead, adjust the DAC write value check to reject values
larger than 12-bit so that they fail explicitly as invalid for the user.

Fixes: 3b8df5fd526e ("iio: Add IIO support for the Measurement Computing CIO-DAC family")
Cc: stable@vger.kernel.org
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/20230311002248.8548-1-william.gray@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/dac/cio-dac.c b/drivers/iio/dac/cio-dac.c
index 791dd999cf291ec5394ec196f0ca6d2b16e98c45..18a64f72fc188dbb0d47ed84860e7e07ba8e2a78 100644 (file)
--- a/drivers/iio/dac/cio-dac.c
+++ b/drivers/iio/dac/cio-dac.c
@@ -66,8 +66,8 @@ static int cio_dac_write_raw(struct iio_dev *indio_dev,
        if (mask != IIO_CHAN_INFO_RAW)
                return -EINVAL;
 
-       /* DAC can only accept up to a 16-bit value */
-       if ((unsigned int)val > 65535)
+       /* DAC can only accept up to a 12-bit value */
+       if ((unsigned int)val > 4095)
                return -EINVAL;
 
        priv->chan_out_states[chan->channel] = val;