@@ -554,47 +554,63 @@ 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;
+ s16 outval;
+
+ 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.
+ */
+ outval = (s16)le16_to_cpu(hw_values[address]);
+ *val = outval;
+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)
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@web.de> Cc: Stephan Gerhold <stephan@gerhold.net> Cc: Michał Mirosław <mirq-linux@rere.qmqm.pl> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- 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 | 68 +++++++++++++++++++------------ 1 file changed, 42 insertions(+), 26 deletions(-)