On 07/29/2013 04:58 PM, Oleksandr Kravchenko wrote:
> From: Oleksandr Kravchenko <[email protected]>
>
> This patch adds IIO driver for Bosch BMA180 triaxial
> acceleration sensor.
> http://omapworld.com/BMA180_111_1002839.pdf
>
> Signed-off-by: Oleksandr Kravchenko <[email protected]>
> ---
> .../devicetree/bindings/iio/accel/bma180.txt | 53 +++
> drivers/iio/accel/Kconfig | 10 +
> drivers/iio/accel/Makefile | 2 +
> drivers/iio/accel/bma180.c | 462
> ++++++++++++++++++++
> 4 files changed, 527 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/accel/bma180.txt
> create mode 100644 drivers/iio/accel/bma180.c
>
> diff --git a/Documentation/devicetree/bindings/iio/accel/bma180.txt
> b/Documentation/devicetree/bindings/iio/accel/bma180.txt
> new file mode 100644
> index 0000000..7c13c84
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/accel/bma180.txt
> @@ -0,0 +1,53 @@
> +* Bosch BMA180 triaxial acceleration sensor
> +
> +http://omapworld.com/BMA180_111_1002839.pdf
> +
> +Required properties:
> +
> + - compatible : should be "bosch,bma180"
> + - reg : the I2C address of the sensor
> +
> +Optional properties:
> +
> + - interrupt-parent : should be the phandle for the interrupt controller
> +
> + - interrupts : interrupt mapping for GPIO IRQ, it shuld by configured with
> + flags IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_EDGE_RISING
> +
> + - range : select the full scale acceleration range
> + 0 : -1g..+1g
> + 1 : -1.5g..+1.5g
> + 2 : -2g..+2g
> + 3 : -3g..+3g
> + 4 : -4g..+4g
> + 5 : -8g..+8g
> + 6 : -16g..+16g
> +
> + - bw : select bandwidth bandwidth
> + 0 : 10Hz
> + 1 : 20Hz
> + 2 : 40Hz
> + 3 : 75Hz
> + 4 : 150Hz
> + 5 : 300Hz
> + Don't use bandwidth frequency more than 300Hz couse it
> + influences the frequency of generating new data interrupts
> + and i2c reading phase can be longer than pheriod of interrupt
> + generation.
> +
> + - mode_config : 0 - select low noise mode, 1 - select low power mode
> +
> + - fuzz : specifies fuzz value that is used to filter noise from the event
> stream
> +
All the four properties above are vendor specific, so they need a vendor
prefix. Also no underscores in property names and no abbreviations. Also I
wonder if some of them should rather be runtime configurable, like range and
bandwidth,
> +Example:
> +
> +bma180@40 {
> + compatible = "bosch,bma180";
> + reg = <0x40>;
> + interrupt-parent = <&gpio6>;
> + interrupts = <18 (IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_EDGE_RISING)>;
> + range = <2>;
> + bw = <0>;
> + mode_config = <1>;
> + fuzz = <555>;
> +};
[...]
> +static int bma180_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan, int *val, int *val2,
> + long mask)
> +{
> + struct bma180_data *data = iio_priv(indio_dev);
> + long tmp = ((s16)data->acc_reg[chan->channel] >> 2)
> + * bma180_range_table[data->range].ratio;
> +
> + if (data->acc_reg[chan->channel] < 0)
> + return data->acc_reg[chan->channel];
> +
> + *val = tmp / 1000000;
> + *val2 = (tmp % 1000000);
> +
This doesn't look as if the device needs a special conversion formula. Just
expose the raw value and ratio as the scale.
> + return IIO_VAL_INT_PLUS_MICRO;
> +}
[...]
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