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Bug: 10134622

Change-Id: Ief5a53f1b5e5eff9ade45763d895029428266980
This commit is contained in:
Clay Murphy
2013-12-19 09:58:28 -08:00
parent b0c939fb6b
commit 8db1fb408c
1 changed files with 29 additions and 682 deletions
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711
include/hardware/sensors.h
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@@ -34,6 +34,12 @@ __BEGIN_DECLS
#define SENSORS_DEVICE_API_VERSION_1_0 HARDWARE_DEVICE_API_VERSION_2(1, 0, SENSORS_HEADER_VERSION)
#define SENSORS_DEVICE_API_VERSION_1_1 HARDWARE_DEVICE_API_VERSION_2(1, 1, SENSORS_HEADER_VERSION)
/**
* Please see the Sensors section of source.android.com for an
* introduction to and detailed descriptions of Android sensor types:
* http://source.android.com/devices/sensors/index.html
*/
/**
* The id of this module
*/
@@ -74,74 +80,14 @@ enum {
META_DATA_VERSION /* always last, leave auto-assigned */
};
/**
* Definition of the axis used by the sensor HAL API
*
* This API is relative to the screen of the device in its default orientation,
* that is, if the device can be used in portrait or landscape, this API
* is only relative to the NATURAL orientation of the screen. In other words,
* the axis are not swapped when the device's screen orientation changes.
* Higher level services /may/ perform this transformation.
*
* x<0 x>0
* ^
* |
* +-----------+--> y>0
* | |
* | |
* | |
* | | / z<0
* | | /
* | | /
* O-----------+/
* |[] [ ] []/
* +----------/+ y<0
* /
* /
* |/ z>0 (toward the sky)
*
* O: Origin (x=0,y=0,z=0)
*
*/
/*
* Interaction with suspend mode
*
* Unless otherwise noted, an enabled sensor shall not prevent the
* SoC to go into suspend mode. It is the responsibility of applications
* to keep a partial wake-lock should they wish to receive sensor
* events while the screen is off. While in suspend mode, and unless
* otherwise noted (batch mode, sensor particularities, ...), enabled sensors'
* events are lost.
*
* Note that conceptually, the sensor itself is not de-activated while in
* suspend mode -- it's just that the data it returns are lost. As soon as
* the SoC gets out of suspend mode, operations resume as usual. Of course,
* in practice sensors shall be disabled while in suspend mode to
* save power, unless batch mode is active, in which case they must
* continue fill their internal FIFO (see the documentation of batch() to
* learn how suspend interacts with batch mode).
*
* In batch mode, and only when the flag SENSORS_BATCH_WAKE_UPON_FIFO_FULL is
* set and supported, the specified sensor must be able to wake-up the SoC and
* be able to buffer at least 10 seconds worth of the requested sensor events.
*
* There are notable exceptions to this behavior, which are sensor-dependent
* (see sensor types definitions below)
*
*
* The sensor type documentation below specifies the wake-up behavior of
* each sensor:
* wake-up: yes this sensor must wake-up the SoC to deliver events
* wake-up: no this sensor shall not wake-up the SoC, events are dropped
*
*/
/*
* Sensor type
*
* Each sensor has a type which defines what this sensor measures and how
* measures are reported. All types are defined below.
* measures are reported. See the Base sensors and Composite sensors lists
* for complete descriptions:
* http://source.android.com/devices/sensors/base_triggers.html
* http://source.android.com/devices/sensors/composite_sensors.html
*
* Device manufacturers (OEMs) can define their own sensor types, for
* their private use by applications or services provided by them. Such
@@ -155,47 +101,6 @@ enum {
*/
#define SENSOR_TYPE_DEVICE_PRIVATE_BASE 0x10000
/*
* Sensor fusion and virtual sensors
*
* Many sensor types are or can be implemented as virtual sensors from
* physical sensors on the device. For instance the rotation vector sensor,
* orientation sensor, step-detector, step-counter, etc...
*
* From the point of view of this API these virtual sensors MUST appear as
* real, individual sensors. It is the responsibility of the driver and HAL
* to make sure this is the case.
*
* In particular, all sensors must be able to function concurrently.
* For example, if defining both an accelerometer and a step counter,
* then both must be able to work concurrently.
*/
/*
* Trigger modes
*
* Sensors can report events in different ways called trigger modes,
* each sensor type has one and only one trigger mode associated to it.
* Currently there are four trigger modes defined:
*
* continuous: events are reported at a constant rate defined by setDelay().
* eg: accelerometers, gyroscopes.
* on-change: events are reported only if the sensor's value has changed.
* setDelay() is used to set a lower limit to the reporting
* period (minimum time between two events).
* The HAL must return an event immediately when an on-change
* sensor is activated.
* eg: proximity, light sensors
* one-shot: upon detection of an event, the sensor deactivates itself and
* then sends a single event. Order matters to avoid race
* conditions. No other event is sent until the sensor get
* reactivated. setDelay() is ignored.
* eg: significant motion sensor
* special: see details in the sensor type specification below
*
*/
/*
* SENSOR_TYPE_META_DATA
* trigger-mode: n/a
@@ -237,30 +142,6 @@ enum {
* All values are in SI units (m/s^2) and measure the acceleration of the
* device minus the force of gravity.
*
* Acceleration sensors return sensor events for all 3 axes at a constant
* rate defined by setDelay().
*
* x: Acceleration on the x-axis
* y: Acceleration on the y-axis
* z: Acceleration on the z-axis
*
* Note that the readings from the accelerometer include the acceleration
* due to gravity (which is opposite to the direction of the gravity vector).
*
* Examples:
* The norm of <x, y, z> should be close to 0 when in free fall.
*
* When the device lies flat on a table and is pushed on its left side
* toward the right, the x acceleration value is positive.
*
* When the device lies flat on a table, the acceleration value is +9.81,
* which correspond to the acceleration of the device (0 m/s^2) minus the
* force of gravity (-9.81 m/s^2).
*
* When the device lies flat on a table and is pushed toward the sky, the
* acceleration value is greater than +9.81, which correspond to the
* acceleration of the device (+A m/s^2) minus the force of
* gravity (-9.81 m/s^2).
*/
#define SENSOR_TYPE_ACCELEROMETER (1)
@@ -272,12 +153,6 @@ enum {
* All values are in micro-Tesla (uT) and measure the geomagnetic
* field in the X, Y and Z axis.
*
* Returned values include calibration mechanisms such that the vector is
* aligned with the magnetic declination and heading of the earth's
* geomagnetic field.
*
* Magnetic Field sensors return sensor events for all 3 axes at a constant
* rate defined by setDelay().
*/
#define SENSOR_TYPE_GEOMAGNETIC_FIELD (2)
#define SENSOR_TYPE_MAGNETIC_FIELD SENSOR_TYPE_GEOMAGNETIC_FIELD
@@ -286,39 +161,11 @@ enum {
* SENSOR_TYPE_ORIENTATION
* trigger-mode: continuous
* wake-up sensor: no
*
*
* All values are angles in degrees.
*
*
* Orientation sensors return sensor events for all 3 axes at a constant
* rate defined by setDelay().
*
* azimuth: angle between the magnetic north direction and the Y axis, around
* the Z axis (0<=azimuth<360).
* 0=North, 90=East, 180=South, 270=West
*
* pitch: Rotation around X axis (-180<=pitch<=180), with positive values when
* the z-axis moves toward the y-axis.
*
* roll: Rotation around Y axis (-90<=roll<=90), with positive values when
* the x-axis moves towards the z-axis.
*
* Note: For historical reasons the roll angle is positive in the clockwise
* direction (mathematically speaking, it should be positive in the
* counter-clockwise direction):
*
* Z
* ^
* (+roll) .--> |
* / |
* | | roll: rotation around Y axis
* X <-------(.)
* Y
* note that +Y == -roll
*
*
*
* Note: This definition is different from yaw, pitch and roll used in aviation
* where the X axis is along the long side of the plane (tail to nose).
*/
#define SENSOR_TYPE_ORIENTATION (3)
@@ -328,17 +175,7 @@ enum {
* wake-up sensor: no
*
* All values are in radians/second and measure the rate of rotation
* around the X, Y and Z axis. The coordinate system is the same as is
* used for the acceleration sensor. Rotation is positive in the
* counter-clockwise direction (right-hand rule). That is, an observer
* looking from some positive location on the x, y or z axis at a device
* positioned on the origin would report positive rotation if the device
* appeared to be rotating counter clockwise. Note that this is the
* standard mathematical definition of positive rotation and does not agree
* with the definition of roll given earlier.
* The range should at least be 17.45 rad/s (ie: ~1000 deg/s).
*
* automatic gyro-drift compensation is allowed but not required.
* around the X, Y and Z axis.
*/
#define SENSOR_TYPE_GYROSCOPE (4)
@@ -368,10 +205,7 @@ enum {
* trigger-mode: on-change
* wake-up sensor: yes
*
* The distance value is measured in centimeters. Note that some proximity
* sensors only support a binary "close" or "far" measurement. In this case,
* the sensor should report its maxRange value in the "far" state and a value
* less than maxRange in the "near" state.
* The value corresponds to the distance to the nearest object in centimeters.
*/
#define SENSOR_TYPE_PROXIMITY (8)
@@ -381,10 +215,7 @@ enum {
* wake-up sensor: no
*
* A gravity output indicates the direction of and magnitude of gravity in
* the devices's coordinates. On Earth, the magnitude is 9.8 m/s^2.
* Units are m/s^2. The coordinate system is the same as is used for the
* acceleration sensor. When the device is at rest, the output of the
* gravity sensor should be identical to that of the accelerometer.
* the devices's coordinates.
*/
#define SENSOR_TYPE_GRAVITY (9)
@@ -395,13 +226,6 @@ enum {
*
* Indicates the linear acceleration of the device in device coordinates,
* not including gravity.
*
* The output is conceptually:
* output of TYPE_ACCELERATION - output of TYPE_GRAVITY
*
* Readings on all axes should be close to 0 when device lies on a table.
* Units are m/s^2.
* The coordinate system is the same as is used for the acceleration sensor.
*/
#define SENSOR_TYPE_LINEAR_ACCELERATION (10)
@@ -412,46 +236,7 @@ enum {
* wake-up sensor: no
*
* The rotation vector symbolizes the orientation of the device relative to the
* East-North-Up coordinates frame. It is usually obtained by integration of
* accelerometer, gyroscope and magnetometer readings.
*
* The East-North-Up coordinate system is defined as a direct orthonormal basis
* where:
* - X points east and is tangential to the ground.
* - Y points north and is tangential to the ground.
* - Z points towards the sky and is perpendicular to the ground.
*
* The orientation of the phone is represented by the rotation necessary to
* align the East-North-Up coordinates with the phone's coordinates. That is,
* applying the rotation to the world frame (X,Y,Z) would align them with the
* phone coordinates (x,y,z).
*
* The rotation can be seen as rotating the phone by an angle theta around
* an axis rot_axis to go from the reference (East-North-Up aligned) device
* orientation to the current device orientation.
*
* The rotation is encoded as the 4 (reordered) components of a unit quaternion:
* sensors_event_t.data[0] = rot_axis.x*sin(theta/2)
* sensors_event_t.data[1] = rot_axis.y*sin(theta/2)
* sensors_event_t.data[2] = rot_axis.z*sin(theta/2)
* sensors_event_t.data[3] = cos(theta/2)
* where
* - rot_axis.x,y,z are the North-East-Up coordinates of a unit length vector
* representing the rotation axis
* - theta is the rotation angle
*
* The quaternion must be of norm 1 (it is a unit quaternion). Failure to ensure
* this will cause erratic client behaviour.
*
* In addition, this sensor reports an estimated heading accuracy.
* sensors_event_t.data[4] = estimated_accuracy (in radians)
* The heading error must be less than estimated_accuracy 95% of the time
*
* This sensor must use a gyroscope and an accelerometer as main orientation
* change input.
*
* This sensor can also include magnetometer input to make up for gyro drift,
* but it cannot be implemented using only a magnetometer.
* East-North-Up coordinates frame.
*/
#define SENSOR_TYPE_ROTATION_VECTOR (11)
@@ -481,35 +266,6 @@ enum {
*
* Similar to SENSOR_TYPE_MAGNETIC_FIELD, but the hard iron calibration is
* reported separately instead of being included in the measurement.
* Factory calibration and temperature compensation should still be applied to
* the "uncalibrated" measurement.
* Separating away the hard iron calibration estimation allows the system to
* better recover from bad hard iron estimation.
*
* All values are in micro-Tesla (uT) and measure the ambient magnetic
* field in the X, Y and Z axis. Assumptions that the the magnetic field
* is due to the Earth's poles should be avoided.
*
* The uncalibrated_magnetic event contains
* - 3 fields for uncalibrated measurement: x_uncalib, y_uncalib, z_uncalib.
* Each is a component of the measured magnetic field, with soft iron
* and temperature compensation applied, but not hard iron calibration.
* These values should be continuous (no re-calibration should cause a jump).
* - 3 fields for hard iron bias estimates: x_bias, y_bias, z_bias.
* Each field is a component of the estimated hard iron calibration.
* They represent the offsets to apply to the calibrated readings to obtain
* uncalibrated readings (x_uncalib ~= x_calibrated + x_bias)
* These values are expected to jump as soon as the estimate of the hard iron
* changes, and they should be stable the rest of the time.
*
* If this sensor is present, then the corresponding
* SENSOR_TYPE_MAGNETIC_FIELD must be present and both must return the
* same sensor_t::name and sensor_t::vendor.
*
* Minimum filtering should be applied to this sensor. In particular, low pass
* filters should be avoided.
*
* See SENSOR_TYPE_MAGNETIC_FIELD for more information
*/
#define SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED (14)
@@ -519,21 +275,7 @@ enum {
* wake-up sensor: no
*
* Similar to SENSOR_TYPE_ROTATION_VECTOR, but not using the geomagnetic
* field. Therefore the Y axis doesn't point north, but instead to some other
* reference. That reference is allowed to drift by the same order of
* magnitude than the gyroscope drift around the Z axis.
*
* This sensor does not report an estimated heading accuracy:
* sensors_event_t.data[4] is reserved and should be set to 0
*
* In the ideal case, a phone rotated and returning to the same real-world
* orientation should report the same game rotation vector
* (without using the earth's geomagnetic field).
*
* This sensor must be based on a gyroscope. It cannot be implemented using
* a magnetometer.
*
* see SENSOR_TYPE_ROTATION_VECTOR for more details
* field.
*/
#define SENSOR_TYPE_GAME_ROTATION_VECTOR (15)
@@ -543,44 +285,10 @@ enum {
* wake-up sensor: no
*
* All values are in radians/second and measure the rate of rotation
* around the X, Y and Z axis. An estimation of the drift on each axis is
* reported as well.
*
* No gyro-drift compensation shall be performed.
* Factory calibration and temperature compensation should still be applied
* to the rate of rotation (angular speeds).
*
* The coordinate system is the same as is
* used for the acceleration sensor. Rotation is positive in the
* counter-clockwise direction (right-hand rule). That is, an observer
* looking from some positive location on the x, y or z axis at a device
* positioned on the origin would report positive rotation if the device
* appeared to be rotating counter clockwise. Note that this is the
* standard mathematical definition of positive rotation and does not agree
* with the definition of roll given earlier.
* The range should at least be 17.45 rad/s (ie: ~1000 deg/s).
*
* Content of an uncalibrated_gyro event: (units are rad/sec)
* x_uncalib : angular speed (w/o drift compensation) around the X axis
* y_uncalib : angular speed (w/o drift compensation) around the Y axis
* z_uncalib : angular speed (w/o drift compensation) around the Z axis
* x_bias : estimated drift around X axis in rad/s
* y_bias : estimated drift around Y axis in rad/s
* z_bias : estimated drift around Z axis in rad/s
*
* IMPLEMENTATION NOTES:
*
* If the implementation is not able to estimate the drift, then this
* sensor MUST NOT be reported by this HAL. Instead, the regular
* SENSOR_TYPE_GYROSCOPE is used without drift compensation.
*
* If this sensor is present, then the corresponding
* SENSOR_TYPE_GYROSCOPE must be present and both must return the
* same sensor_t::name and sensor_t::vendor.
* around the X, Y and Z axis.
*/
#define SENSOR_TYPE_GYROSCOPE_UNCALIBRATED (16)
/*
* SENSOR_TYPE_SIGNIFICANT_MOTION
* trigger-mode: one-shot
@@ -589,45 +297,6 @@ enum {
* A sensor of this type triggers an event each time significant motion
* is detected and automatically disables itself.
* The only allowed value to return is 1.0.
*
* A significant motion is a motion that might lead to a change in the user
* location.
* Examples of such motions are:
* walking, biking, sitting in a moving car, coach or train.
* Examples of situations that should not trigger significant motion:
* - phone in pocket and person is not moving
* - phone is on a table, even if the table shakes a bit due to nearby traffic
* or washing machine
*
* A note on false positive / false negative / power consumption tradeoff
* - The goal of this sensor is to save power.
* - Triggering an event when the user is not moving (false positive) is costly
* in terms of power, so it should be avoided.
* - Not triggering an event when the user is moving (false negative) is
* acceptable as long as it is not done repeatedly. If the user has been
* walking for 10 seconds, not triggering an event within those 10 seconds
* is not acceptable.
*
* IMPORTANT NOTE: this sensor type is very different from other types
* in that it must work when the screen is off without the need of
* holding a partial wake-lock and MUST allow the SoC to go into suspend.
* When significant motion is detected, the sensor must awaken the SoC and
* the event be reported.
*
* If a particular hardware cannot support this mode of operation then this
* sensor type MUST NOT be reported by the HAL. ie: it is not acceptable
* to "emulate" this sensor in the HAL.
*
* The whole point of this sensor type is to save power by keeping the
* SoC in suspend mode when the device is at rest.
*
* When the sensor is not activated, it must also be deactivated in the
* hardware: it must not wake up the SoC anymore, even in case of
* significant motion.
*
* setDelay() has no effect and is ignored.
* Once a "significant motion" event is returned, a sensor of this type
* must disables itself automatically, as if activate(..., 0) had been called.
*/
#define SENSOR_TYPE_SIGNIFICANT_MOTION (17)
@@ -639,21 +308,8 @@ enum {
* wake-up sensor: no
*
* A sensor of this type triggers an event each time a step is taken
* by the user. The only allowed value to return is 1.0 and an event is
* generated for each step. Like with any other event, the timestamp
* indicates when the event (here the step) occurred, this corresponds to when
* the foot hit the ground, generating a high variation in acceleration.
*
* While this sensor operates, it shall not disrupt any other sensors, in
* particular, but not limited to, the accelerometer; which might very well
* be in use as well.
*
* This sensor must be low power. That is, if the step detection cannot be
* done in hardware, this sensor should not be defined. Also, when the
* step detector is activated and the accelerometer is not, only steps should
* trigger interrupts (not accelerometer data).
*
* setDelay() has no impact on this sensor type
* by the user. The only allowed value to return is 1.0 and an event
* is generated for each step.
*/
#define SENSOR_TYPE_STEP_DETECTOR (18)
@@ -667,46 +323,6 @@ enum {
* A sensor of this type returns the number of steps taken by the user since
* the last reboot while activated. The value is returned as a uint64_t and is
* reset to zero only on a system / android reboot.
*
* The timestamp of the event is set to the time when the first step
* for that event was taken.
* See SENSOR_TYPE_STEP_DETECTOR for the signification of the time of a step.
*
* The minimum size of the hardware's internal counter shall be 16 bits
* (this restriction is here to avoid too frequent wake-ups when the
* delay is very large).
*
* IMPORTANT NOTE: this sensor type is different from other types
* in that it must work when the screen is off without the need of
* holding a partial wake-lock and MUST allow the SoC to go into suspend.
* Unlike other sensors, while in suspend mode this sensor must stay active,
* no events are reported during that time but, steps continue to be
* accounted for; an event will be reported as soon as the SoC resumes if
* the timeout has expired.
*
* In other words, when the screen is off and the device allowed to
* go into suspend mode, we don't want to be woken up, regardless of the
* setDelay() value, but the steps shall continue to be counted.
*
* The driver must however ensure that the internal step count never
* overflows. It is allowed in this situation to wake the SoC up so the
* driver can do the counter maintenance.
*
* While this sensor operates, it shall not disrupt any other sensors, in
* particular, but not limited to, the accelerometer; which might very well
* be in use as well.
*
* If a particular hardware cannot support these modes of operation then this
* sensor type MUST NOT be reported by the HAL. ie: it is not acceptable
* to "emulate" this sensor in the HAL.
*
* This sensor must be low power. That is, if the step detection cannot be
* done in hardware, this sensor should not be defined. Also, when the
* step counter is activated and the accelerometer is not, only steps should
* trigger interrupts (not accelerometer data).
*
* The whole point of this sensor type is to save power by keeping the
* SoC in suspend mode when the device is at rest.
*/
#define SENSOR_TYPE_STEP_COUNTER (19)
@@ -718,18 +334,6 @@ enum {
*
* Similar to SENSOR_TYPE_ROTATION_VECTOR, but using a magnetometer instead
* of using a gyroscope.
*
* This sensor must be based on a magnetometer. It cannot be implemented using
* a gyroscope, and gyroscope input cannot be used by this sensor, as the
* goal of this sensor is to be low power.
* The accelerometer can be (and usually is) used.
*
* Just like SENSOR_TYPE_ROTATION_VECTOR, this sensor reports an estimated
* heading accuracy:
* sensors_event_t.data[4] = estimated_accuracy (in radians)
* The heading error must be less than estimated_accuracy 95% of the time
*
* see SENSOR_TYPE_ROTATION_VECTOR for more details
*/
#define SENSOR_TYPE_GEOMAGNETIC_ROTATION_VECTOR (20)
@@ -966,7 +570,9 @@ struct sensor_t {
/*
* sensors_poll_device_t is used with SENSORS_DEVICE_API_VERSION_0_1
* and is present for backward binary and source compatibility.
* (see documentation of the hooks in struct sensors_poll_device_1 below)
* See the Sensors HAL interface section for complete descriptions of the
* following functions:
* http://source.android.com/devices/sensors/index.html#hal
*/
struct sensors_poll_device_t {
struct hw_device_t common;
@@ -991,70 +597,24 @@ typedef struct sensors_poll_device_1 {
struct {
struct hw_device_t common;
/* Activate/de-activate one sensor.
/* Activate/de-activate one sensor. Return 0 on success, negative
*
* handle is the handle of the sensor to change.
* enabled set to 1 to enable, or 0 to disable the sensor.
*
* if enabled is set to 1, the sensor is activated even if
* setDelay() wasn't called before. In this case, a default rate
* should be used.
*
* unless otherwise noted in the sensor types definitions, an
* activated sensor never prevents the SoC to go into suspend
* mode; that is, the HAL shall not hold a partial wake-lock on
* behalf of applications.
*
* one-shot sensors de-activate themselves automatically upon
* receiving an event and they must still accept to be deactivated
* through a call to activate(..., ..., 0).
*
* if "enabled" is 1 and the sensor is already activated, this
* function is a no-op and succeeds.
*
* if "enabled" is 0 and the sensor is already de-activated,
* this function is a no-op and succeeds.
*
* return 0 on success, negative errno code otherwise
* Return 0 on success, negative errno code otherwise.
*/
int (*activate)(struct sensors_poll_device_t *dev,
int handle, int enabled);
/**
* Set the events's period in nanoseconds for a given sensor.
*
* What the period_ns parameter means depends on the specified
* sensor's trigger mode:
*
* continuous: setDelay() sets the sampling rate.
* on-change: setDelay() limits the delivery rate of events
* one-shot: setDelay() is ignored. it has no effect.
* special: see specific sensor type definitions
*
* For continuous and on-change sensors, if the requested value is
* less than sensor_t::minDelay, then it's silently clamped to
* sensor_t::minDelay unless sensor_t::minDelay is 0, in which
* case it is clamped to >= 1ms.
*
* setDelay will not be called when the sensor is in batching mode.
* In this case, batch() will be called with the new period.
*
* @return 0 if successful, < 0 on error
*/
int (*setDelay)(struct sensors_poll_device_t *dev,
int handle, int64_t period_ns);
/**
* Returns an array of sensor data.
* This function must block until events are available.
*
* return the number of events read on success, or -errno in case
* of an error.
*
* The number of events returned in data must be less or equal
* to the "count" argument.
*
* This function shall never return 0 (no event).
*/
int (*poll)(struct sensors_poll_device_t *dev,
sensors_event_t* data, int count);
@@ -1063,200 +623,9 @@ typedef struct sensors_poll_device_1 {
/*
* Enables batch mode for the given sensor and sets the delay between events
*
* A timeout value of zero disables batch mode for the given sensor.
*
* The period_ns parameter is equivalent to calling setDelay() -- this
* function both enables or disables the batch mode AND sets the events's
* period in nanosecond. See setDelay() above for a detailed explanation of
* the period_ns parameter.
*
* BATCH MODE:
* -----------
* In non-batch mode, all sensor events must be reported as soon as they
* are detected. For example, an accelerometer activated at 50Hz will
* trigger interrupts 50 times per second.
* While in batch mode, sensor events do not need to be reported as soon
* as they are detected. They can be temporarily stored in batches and
* reported in batches, as long as no event is delayed by more than
* "timeout" nanoseconds. That is, all events since the previous batch
* are recorded and returned all at once. This allows to reduce the amount
* of interrupts sent to the SoC, and allow the SoC to switch to a lower
* power state (Idle) while the sensor is capturing and batching data.
*
* setDelay() is not affected and it behaves as usual.
*
* Each event has a timestamp associated with it, the timestamp
* must be accurate and correspond to the time at which the event
* physically happened.
*
* Batching does not modify the behavior of poll(): batches from different
* sensors can be interleaved and split. As usual, all events from the same
* sensor are time-ordered.
*
* BEHAVIOUR OUTSIDE OF SUSPEND MODE:
* ----------------------------------
*
* When the SoC is awake (not in suspend mode), events must be reported in
* batches at least every "timeout". No event shall be dropped or lost.
* If internal h/w FIFOs fill-up before the timeout, then events are
* reported at that point to ensure no event is lost.
*
*
* NORMAL BEHAVIOR IN SUSPEND MODE:
* ---------------------------------
*
* By default, batch mode doesn't significantly change the interaction with
* suspend mode. That is, sensors must continue to allow the SoC to
* go into suspend mode and sensors must stay active to fill their
* internal FIFO. In this mode, when the FIFO fills up, it shall wrap
* around (basically behave like a circular buffer, overwriting events).
* As soon as the SoC comes out of suspend mode, a batch is produced with
* as much as the recent history as possible, and batch operation
* resumes as usual.
*
* The behavior described above allows applications to record the recent
* history of a set of sensor while keeping the SoC into suspend. It
* also allows the hardware to not have to rely on a wake-up interrupt line.
*
* WAKE_UPON_FIFO_FULL BEHAVIOR IN SUSPEND MODE:
* ----------------------------------------------
*
* There are cases, however, where an application cannot afford to lose
* any events, even when the device goes into suspend mode.
* For a given rate, if a sensor has the capability to store at least 10
* seconds worth of events in its FIFO and is able to wake up the Soc, it
* can implement an optional secondary mode: the WAKE_UPON_FIFO_FULL mode.
*
* The caller will set the SENSORS_BATCH_WAKE_UPON_FIFO_FULL flag to
* activate this mode. If the sensor does not support this mode, batch()
* will fail when the flag is set.
*
* When running with the WAKE_UPON_FIFO_FULL flag set, no events can be
* lost. When the FIFO is getting full, the sensor must wake up the SoC from
* suspend and return a batch before the FIFO fills-up.
* Depending on the device, it might take a few miliseconds for the SoC to
* entirely come out of suspend and start flushing the FIFO. Enough head
* room must be allocated in the FIFO to allow the device to entirely come
* out of suspend without the FIFO overflowing (no events shall be lost).
*
* Implementing the WAKE_UPON_FIFO_FULL mode is optional.
* If the hardware cannot support this mode, or if the physical
* FIFO is so small that the device would never be allowed to go into
* suspend for at least 10 seconds, then this function MUST fail when
* the flag SENSORS_BATCH_WAKE_UPON_FIFO_FULL is set, regardless of
* the value of the timeout parameter.
*
*
* DRY RUN:
* --------
*
* If the flag SENSORS_BATCH_DRY_RUN is set, this function returns
* without modifying the batch mode or the event period and has no side
* effects, but returns errors as usual (as it would if this flag was
* not set). This flag is used to check if batch mode is available for a
* given configuration -- in particular for a given sensor at a given rate.
*
*
* Return values:
* --------------
*
* Because sensors must be independent, the return value must not depend
* on the state of the system (whether another sensor is on or not),
* nor on whether the flag SENSORS_BATCH_DRY_RUN is set (in other words,
* if a batch call with SENSORS_BATCH_DRY_RUN is successful,
* the same call without SENSORS_BATCH_DRY_RUN must succeed as well).
*
* When timeout is not 0:
* If successful, 0 is returned.
* If the specified sensor doesn't support batch mode, return -EINVAL.
* If the specified sensor's trigger-mode is one-shot, return -EINVAL.
* If WAKE_UPON_FIFO_FULL is specified and the specified sensor's internal
* FIFO is too small to store at least 10 seconds worth of data at the
* given rate, -EINVAL is returned. Note that as stated above, this has to
* be determined at compile time, and not based on the state of the
* system.
* If some other constraints above cannot be satisfied, return -EINVAL.
*
* Note: the timeout parameter, when > 0, has no impact on whether this
* function succeeds or fails.
*
* When timeout is 0:
* The caller will never set the wake_upon_fifo_full flag.
* The function must succeed, and batch mode must be deactivated.
*
* Independently of whether DRY_RUN is specified, When the call to batch()
* fails, no state should be changed. In particular, a failed call to
* batch() should not change the rate of the sensor. Example:
* setDelay(..., 10ms)
* batch(..., 20ms, ...) fails
* rate should stay 10ms.
*
*
* IMPLEMENTATION NOTES:
* ---------------------
*
* Batch mode, if supported, should happen at the hardware level,
* typically using hardware FIFOs. In particular, it SHALL NOT be
* implemented in the HAL, as this would be counter productive.
* The goal here is to save significant amounts of power.
*
* In some implementations, events from several sensors can share the
* same physical FIFO. In that case, all events in the FIFO can be sent and
* processed by the HAL as soon as one batch must be reported.
* For example, if the following sensors are activated:
* - accelerometer batched with timeout = 20s
* - gyroscope batched with timeout = 5s
* then the accelerometer batches can be reported at the same time the
* gyroscope batches are reported (every 5 seconds)
*
* Batch mode can be enabled or disabled at any time, in particular
* while the specified sensor is already enabled, and this shall not
* result in the loss of events.
*
* COMPARATIVE IMPORTANCE OF BATCHING FOR DIFFERENT SENSORS:
* ---------------------------------------------------------
*
* On platforms on which hardware fifo size is limited, the system designers
* might have to choose how much fifo to reserve for each sensor. To help
* with this choice, here is a list of applications made possible when
* batching is implemented on the different sensors.
*
* High value: Low power pedestrian dead reckoning
* Target batching time: 20 seconds to 1 minute
* Sensors to batch:
* - Step detector
* - Rotation vector or game rotation vector at 5Hz
* Gives us step and heading while letting the SoC go to Suspend.
*
* High value: Medium power activity/gesture recognition
* Target batching time: 3 seconds
* Sensors to batch: accelerometer between 20Hz and 50Hz
* Allows recognizing arbitrary activities and gestures without having
* to keep the SoC fully awake while the data is collected.
*
* Medium-high value: Interrupt load reduction
* Target batching time: < 1 second
* Sensors to batch: any high frequency sensor.
* If the gyroscope is set at 800Hz, even batching just 10 gyro events can
* reduce the number of interrupts from 800/second to 80/second.
*
* Medium value: Continuous low frequency data collection
* Target batching time: > 1 minute
* Sensors to batch: barometer, humidity sensor, other low frequency
* sensors.
* Allows creating monitoring applications at low power.
*
* Medium value: Continuous full-sensors collection
* Target batching time: > 1 minute
* Sensors to batch: all, at high frequencies
* Allows full collection of sensor data while leaving the SoC in
* suspend mode. Only to consider if fifo space is not an issue.
*
* In each of the cases above, if WAKE_UPON_FIFO_FULL is implemented, the
* applications might decide to let the SoC go to suspend, allowing for even
* more power savings.
* Enables batch mode for the given sensor and sets the delay between events.
* See the Batching sensor results page for details:
* http://source.android.com/devices/sensors/batching.html
*/
int (*batch)(struct sensors_poll_device_1* dev,
int handle, int flags, int64_t period_ns, int64_t timeout);
@@ -1264,29 +633,7 @@ typedef struct sensors_poll_device_1 {
/*
* Flush adds a META_DATA_FLUSH_COMPLETE event (sensors_event_meta_data_t)
* to the end of the "batch mode" FIFO for the specified sensor and flushes
* the FIFO; those events are delivered as usual (i.e.: as if the batch
* timeout had expired) and removed from the FIFO.
*
* See the META_DATA_FLUSH_COMPLETE section for details about the
* META_DATA_FLUSH_COMPLETE event.
*
* The flush happens asynchronously (i.e.: this function must return
* immediately).
*
* If the implementation uses a single FIFO for several sensors, that
* FIFO is flushed and the META_DATA_FLUSH_COMPLETE event is added only
* for the specified sensor.
*
* If the specified sensor wasn't in batch mode, flush succeeds and
* promptly sends a META_DATA_FLUSH_COMPLETE event for that sensor.
*
* If the FIFO was empty at the time of the call, flush returns
* 0 (success) and promptly sends a META_DATA_FLUSH_COMPLETE event
* for that sensor.
*
* If the specified sensor wasn't enabled, flush returns -EINVAL.
*
* return 0 on success, negative errno code otherwise.
* the FIFO.
*/
int (*flush)(struct sensors_poll_device_1* dev, int handle);