iio: Fix two mpl3115 issues in measurement conversion

commit d29f592929489d0a7c414396fae28119f3d280e1 upstream.

(i) pressure is 20-bit unsigned, not signed; the buffer description
is incorrect; for raw reads, this is just cosmetic

(ii) temperature is 12-bit signed, not 16-bit; this affects
readout of temperatures below zero as the sign bit is incorrectly
processed

reported via private mail

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Reported-by: Robert Deliën <robert@delien.nl>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iio/pressure/mpl3115.c b/drivers/iio/pressure/mpl3115.c
index ac8c8ab..fe53669 100644 (file)
--- a/drivers/iio/pressure/mpl3115.c
+++ b/drivers/iio/pressure/mpl3115.c
@@ -98,7 +98,7 @@ static int mpl3115_read_raw(struct iio_dev *indio_dev,
                        mutex_unlock(&data->lock);
                        if (ret < 0)
                                return ret;
-                       *val = sign_extend32(be32_to_cpu(tmp) >> 12, 23);
+                       *val = be32_to_cpu(tmp) >> 12;
                        return IIO_VAL_INT;
                case IIO_TEMP: /* in 0.0625 celsius / LSB */
                        mutex_lock(&data->lock);
@@ -112,7 +112,7 @@ static int mpl3115_read_raw(struct iio_dev *indio_dev,
                        mutex_unlock(&data->lock);
                        if (ret < 0)
                                return ret;
-                       *val = sign_extend32(be32_to_cpu(tmp) >> 20, 15);
+                       *val = sign_extend32(be32_to_cpu(tmp) >> 20, 11);
                        return IIO_VAL_INT;
                default:
                        return -EINVAL;
@@ -185,7 +185,7 @@ static const struct iio_chan_spec mpl3115_channels[] = {
                        BIT(IIO_CHAN_INFO_SCALE),
                .scan_index = 0,
                .scan_type = {
-                       .sign = 's',
+                       .sign = 'u',
                        .realbits = 20,
                        .storagebits = 32,
                        .shift = 12,