[PATCH] iio: ak8975: Support adapters limited to BYTE_DATA

From: Crestez Dan Leonard
Date: Fri Apr 29 2016 - 15:05:40 EST


The device has simple 8-bit registers but the driver incorrectly uses
block or word reads without checking functionality bits.

Fix by using i2c_smbus_read_i2c_block_data_or_emulated instead of
i2c_smbus_read_i2c_block_data or i2c_smbus_read_word_data. This will
check functionality bits and use the fastest available transfer method.

Signed-off-by: Crestez Dan Leonard <leonard.crestez@xxxxxxxxx>
---
drivers/iio/magnetometer/ak8975.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
index dbf0661..c24b8a5 100644
--- a/drivers/iio/magnetometer/ak8975.c
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -430,8 +430,8 @@ static int ak8975_who_i_am(struct i2c_client *client,
* AK8975 | DEVICE_ID | NA
* AK8963 | DEVICE_ID | NA
*/
- ret = i2c_smbus_read_i2c_block_data(client, AK09912_REG_WIA1,
- 2, wia_val);
+ ret = i2c_smbus_read_i2c_block_data_or_emulated(
+ client, AK09912_REG_WIA1, 2, wia_val);
if (ret < 0) {
dev_err(&client->dev, "Error reading WIA\n");
return ret;
@@ -543,9 +543,9 @@ static int ak8975_setup(struct i2c_client *client)
}

/* Get asa data and store in the device data. */
- ret = i2c_smbus_read_i2c_block_data(client,
- data->def->ctrl_regs[ASA_BASE],
- 3, data->asa);
+ ret = i2c_smbus_read_i2c_block_data_or_emulated(
+ client, data->def->ctrl_regs[ASA_BASE],
+ 3, data->asa);
if (ret < 0) {
dev_err(&client->dev, "Not able to read asa data\n");
return ret;
@@ -686,6 +686,7 @@ static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
struct ak8975_data *data = iio_priv(indio_dev);
const struct i2c_client *client = data->client;
const struct ak_def *def = data->def;
+ u16 buff;
int ret;

mutex_lock(&data->lock);
@@ -694,14 +695,17 @@ static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
if (ret)
goto exit;

- ret = i2c_smbus_read_word_data(client, def->data_regs[index]);
+ ret = i2c_smbus_read_i2c_block_data_or_emulated(
+ client, def->data_regs[index],
+ sizeof(buff), (u8*)&buff);
if (ret < 0)
goto exit;

mutex_unlock(&data->lock);

- /* Clamp to valid range. */
- *val = clamp_t(s16, ret, -def->range, def->range);
+ /* Swap bytes and convert to valid range. */
+ buff = le16_to_cpu(buff);
+ *val = clamp_t(s16, buff, -def->range, def->range);
return IIO_VAL_INT;

exit:
--
2.5.5