> Reading all axis values in one i2c transfer reduces the delays
> introduced by the i2c bus. In case i2c block read is not supported,
> fallback to reading each axis as a separate word.
see comments inline below
> Signed-off-by: Adriana Reus <adriana.r...@intel.com>
> Signed-off-by: Irina Tirdea <irina.tir...@intel.com>
> Reviewed-by: Srinivas Pandruvada <srinivas.pandruv...@linux.intel.com>
> ---
> drivers/iio/accel/kxcjk-1013.c | 44
> +++++++++++++++++++++++++++++++++---------
> 1 file changed, 35 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/iio/accel/kxcjk-1013.c b/drivers/iio/accel/kxcjk-1013.c
> index 5f27787..bfa2899 100644
> --- a/drivers/iio/accel/kxcjk-1013.c
> +++ b/drivers/iio/accel/kxcjk-1013.c
> @@ -109,6 +109,8 @@ struct kxcjk1013_data {
> int64_t timestamp;
> enum kx_chipset chipset;
> bool is_smo8500_device;
> + s32 (*read_block_data)(const struct i2c_client *client, u8 command,
> + u8 length, u8 *values);
probably this could/should be done in the i2c layer or we end up adding a
similar function in every driver?
> };
>
> enum kxcjk1013_axis {
> @@ -216,6 +218,23 @@ static const struct {
> {800, 0, 0x06},
> {1600, 0, 0x06} };
>
> +static s32 kxcjk1013_read_block_data(const struct i2c_client *client,
> + u8 command, u8 length, u8 *values)
> +{
> + s32 data;
> + u8 i;
> +
> + for (i = 0; i < length; i += 2) {
> + data = i2c_smbus_read_word_data(client, command + i);
> + if (data < 0)
> + return data;
> +
> + values[i] = data & 0xFF;
> + values[i+1] = data >> 8;
this is incorrect; it forces the data to be little endian, however, the
endianness (as specified in the driver's .scan_type) is IIO_CPU -- the
code breaks for big-endian CPUs
since _read_i2c_block_data() can't do endianness conversion (and the chip
does i2c endianness, i.e. little-endian), the .scan_type should become
IIO_LE and above code is correct again but still ugly :)
bottom line: change .scan_type to IIO_LE
> + }
> + return i;
> +}
> +
> static int kxcjk1013_set_mode(struct kxcjk1013_data *data,
> enum kxcjk1013_mode mode)
> {
> @@ -955,18 +974,14 @@ static irqreturn_t kxcjk1013_trigger_handler(int irq,
> void *p)
> struct iio_poll_func *pf = p;
> struct iio_dev *indio_dev = pf->indio_dev;
> struct kxcjk1013_data *data = iio_priv(indio_dev);
> - int bit, ret, i = 0;
> + int ret;
>
> mutex_lock(&data->mutex);
> - for (bit = 0; bit < AXIS_MAX; bit++) {
> - ret = kxcjk1013_get_acc_reg(data, bit);
> - if (ret < 0) {
> - mutex_unlock(&data->mutex);
> - goto err;
> - }
> - data->buffer[i++] = ret;
> - }
> + ret = data->read_block_data(data->client, KXCJK1013_REG_XOUT_L,
> + AXIS_MAX * 2, (u8 *) data->buffer);
> mutex_unlock(&data->mutex);
> + if (ret < 0)
> + goto err;
>
> iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
> data->timestamp);
> @@ -1196,6 +1211,11 @@ static int kxcjk1013_probe(struct i2c_client *client,
> const char *name;
> int ret;
>
> + if (!i2c_check_functionality(client->adapter,
> + I2C_FUNC_SMBUS_BYTE_DATA |
> + I2C_FUNC_SMBUS_READ_WORD_DATA))
> + return -ENODEV;
> +
> indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> if (!indio_dev)
> return -ENOMEM;
> @@ -1204,6 +1224,12 @@ static int kxcjk1013_probe(struct i2c_client *client,
> i2c_set_clientdata(client, indio_dev);
> data->client = client;
>
> + if (i2c_check_functionality(client->adapter,
> + I2C_FUNC_SMBUS_READ_I2C_BLOCK))
> + data->read_block_data = i2c_smbus_read_i2c_block_data;
> + else
> + data->read_block_data = kxcjk1013_read_block_data;
> +
> pdata = dev_get_platdata(&client->dev);
> if (pdata)
> data->active_high_intr = pdata->active_high_intr;
>
--
Peter Meerwald
+43-664-2444418 (mobile)
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