This adds a mode of operation that consumes less power by lesser oversampling. It's exposed in IIO sysfs as in_accelX_power_mode, as documented.
It consumes roughly half the power the default low_noise mode does. See the datasheet for details. Signed-off-by: Martin Kepplinger <[email protected]> Signed-off-by: Christoph Muellner <[email protected]> --- drivers/iio/accel/mma8452.c | 55 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c index 5ca0d16..5b5abec 100644 --- a/drivers/iio/accel/mma8452.c +++ b/drivers/iio/accel/mma8452.c @@ -75,6 +75,9 @@ #define MMA8452_CTRL_DR_DEFAULT 0x4 /* 50 Hz sample frequency */ #define MMA8452_CTRL_REG2 0x2b #define MMA8452_CTRL_REG2_RST BIT(6) +#define MMA8452_CTRL_REG2_MODS_MASK 0x1b +#define MMA8452_CTRL_REG2_MODS_NORMAL 0x00 +#define MMA8452_CTRL_REG2_MODS_LOW_POWER 0x1b #define MMA8452_CTRL_REG4 0x2d #define MMA8452_CTRL_REG5 0x2e #define MMA8452_OFF_X 0x2f @@ -950,6 +953,56 @@ static struct attribute_group mma8452_event_attribute_group = { .attrs = mma8452_event_attributes, }; +static const char * const mma8452_power_modes[] = {"low_noise", "low_power"}; + +static int mma8452_get_power_mode(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan) +{ + struct mma8452_data *data = iio_priv(indio_dev); + int reg; + + reg = i2c_smbus_read_byte_data(data->client, + MMA8452_CTRL_REG2); + if (reg < 0) + return reg; + + return !(reg & MMA8452_CTRL_REG2_MODS_MASK); +} + +static int mma8452_set_power_mode(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan, + unsigned int mode) +{ + struct mma8452_data *data = iio_priv(indio_dev); + int reg; + + reg = i2c_smbus_read_byte_data(data->client, + MMA8452_CTRL_REG2); + if (reg < 0) + return reg; + + reg &= ~MMA8452_CTRL_REG2_MODS_MASK; + if (mode) + reg |= MMA8452_CTRL_REG2_MODS_LOW_POWER; + else + reg |= MMA8452_CTRL_REG2_MODS_NORMAL; + + return mma8452_change_config(data, MMA8452_CTRL_REG2, reg); +} + +static const struct iio_enum mma8452_power_mode_enum = { + .items = mma8452_power_modes, + .num_items = ARRAY_SIZE(mma8452_power_modes), + .get = mma8452_get_power_mode, + .set = mma8452_set_power_mode, +}; + +static const struct iio_chan_spec_ext_info mma8452_ext_info[] = { + IIO_ENUM("power_mode", true, &mma8452_power_mode_enum), + IIO_ENUM_AVAILABLE("power_mode", &mma8452_power_mode_enum), + { }, +}; + #define MMA8452_FREEFALL_CHANNEL(modifier) { \ .type = IIO_ACCEL, \ .modified = 1, \ @@ -987,6 +1040,7 @@ static struct attribute_group mma8452_event_attribute_group = { }, \ .event_spec = mma8452_transient_event, \ .num_event_specs = ARRAY_SIZE(mma8452_transient_event), \ + .ext_info = mma8452_ext_info, \ } #define MMA8652_CHANNEL(axis, idx, bits) { \ @@ -1007,6 +1061,7 @@ static struct attribute_group mma8452_event_attribute_group = { }, \ .event_spec = mma8452_motion_event, \ .num_event_specs = ARRAY_SIZE(mma8452_motion_event), \ + .ext_info = mma8452_ext_info, \ } static const struct iio_chan_spec mma8451_channels[] = { -- 2.1.4
