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 <martink@xxxxxxxxx>
Signed-off-by: Christoph Muellner <christoph.muellner@xxxxxxxxxxxxxxxxxxxxx>
---
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
--
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