This breaks out the measurement code to its own function
so we can handle this without swirling it up with the
big switch() statement inside ak8974_read_raw().
Keep a local s16 helper variable for the signed value
coming out of the measurement before assigning it to the
integer *val. The local variable makes the code easier
to read and the compiler will optimize it if possible.
Cc: Nick Reitemeyer <nick.reitemeyer@xxxxxx>
Cc: Stephan Gerhold <stephan@xxxxxxxxxxx>
Reviewed-by: Michał Mirosław <mirq-linux@xxxxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
ChangeLog v3->v4:
- Assign the casted s16 to the int *val.
- Collect Michał's review tag.
ChangeLog v2->v3:
- Return directly from the raw read function, we
need no goto:s as we got rid of the lock.
- Change the measurement function to return an int *
after measurement and just pass *val
to the function saving a local variable.
- Insert a comment explaining the explicit cast to
(s16).
- Rename function as ak8974_measure_channel() so the
name states exactly what is going on.
- Break out as a separate patch.
---
drivers/iio/magnetometer/ak8974.c | 66 +++++++++++++++++++------------
1 file changed, 40 insertions(+), 26 deletions(-)
diff --git a/drivers/iio/magnetometer/ak8974.c b/drivers/iio/magnetometer/ak8974.c
index 7d585c3b7e1e..fb6d84b79a7a 100644
--- a/drivers/iio/magnetometer/ak8974.c
+++ b/drivers/iio/magnetometer/ak8974.c
@@ -554,47 +554,61 @@ static int ak8974_detect(struct ak8974 *ak8974)
return 0;
}
+static int ak8974_measure_channel(struct ak8974 *ak8974, unsigned long address,
+ int *val)
+{
+ __le16 hw_values[3];
+ int ret;
+
+ pm_runtime_get_sync(&ak8974->i2c->dev);
+ mutex_lock(&ak8974->lock);
+
+ /*
+ * We read all axes and discard all but one, for optimized
+ * reading, use the triggered buffer.
+ */
+ ret = ak8974_trigmeas(ak8974);
+ if (ret)
+ goto out_unlock;
+ ret = ak8974_getresult(ak8974, hw_values);
+ if (ret)
+ goto out_unlock;
+ /*
+ * This explicit cast to (s16) is necessary as the measurement
+ * is done in 2's complement with positive and negative values.
+ * The follwing assignment to *val will then convert the signed
+ * s16 value to a signed int value.
+ */
+ *val = (s16)le16_to_cpu(hw_values[address]);
+out_unlock:
+ mutex_unlock(&ak8974->lock);
+ pm_runtime_mark_last_busy(&ak8974->i2c->dev);
+ pm_runtime_put_autosuspend(&ak8974->i2c->dev);
+
+ return ret;
+}
+
static int ak8974_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2,
long mask)
{
struct ak8974 *ak8974 = iio_priv(indio_dev);
- __le16 hw_values[3];
- int ret = -EINVAL;
-
- pm_runtime_get_sync(&ak8974->i2c->dev);
- mutex_lock(&ak8974->lock);
+ int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
if (chan->address > 2) {
dev_err(&ak8974->i2c->dev, "faulty channel address\n");
- ret = -EIO;
- goto out_unlock;
+ return -EIO;
}
- ret = ak8974_trigmeas(ak8974);
+ ret = ak8974_measure_channel(ak8974, chan->address, val);
if (ret)
- goto out_unlock;
- ret = ak8974_getresult(ak8974, hw_values);
- if (ret)
- goto out_unlock;
-
- /*
- * We read all axes and discard all but one, for optimized
- * reading, use the triggered buffer.
- */
- *val = (s16)le16_to_cpu(hw_values[chan->address]);
-
- ret = IIO_VAL_INT;
+ return ret;
+ return IIO_VAL_INT;
}
- out_unlock:
- mutex_unlock(&ak8974->lock);
- pm_runtime_mark_last_busy(&ak8974->i2c->dev);
- pm_runtime_put_autosuspend(&ak8974->i2c->dev);
-
- return ret;
+ return -EINVAL;
}
static void ak8974_fill_buffer(struct iio_dev *indio_dev)
--
2.21.1
