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# Dynamic Sensors
[TOC]
## Links
* [Sensor HAL dynamic sensor support](https://source.android.com/devices/sensors/sensors-hal2#dynamic-sensors)
* [Sensors Multi-HAL](https://source.android.com/devices/sensors/sensors-multihal)
## Adding dynamic sensor support to a device
A few files need to be modified to add dynamic sensor support to a device. The
dynamic sensor HAL must be enabled in the device product makefile and in the
sensor sub-HAL configuration file, raw HID devices must be configured, and raw
HID device and dynamic sensor property permissions must be set up in the SELinux
policy files.
```shell
acme-co$ git -C device/acme/rocket-phone diff
diff --git a/sensor_hal/hals.conf b/sensor_hal/hals.conf
index a1f4b8b..d112546 100644
--- a/sensor_hal/hals.conf
+++ b/sensor_hal/hals.conf
@@ -1 +1,2 @@
+sensors.dynamic_sensor_hal.so
sensors.rocket-phone.so
diff --git a/rocket-phone.mk b/rocket-phone.mk
index 3fc8538..b1bd8a1 100644
--- a/rocket-phone.mk
+++ b/rocket-phone.mk
@@ -73,6 +73,9 @@
PRODUCT_PACKAGES += sensors.rocket-phone
PRODUCT_PACKAGES += thruster_stats
+# Add the dynamic sensor HAL.
+PRODUCT_PACKAGES += sensors.dynamic_sensor_hal
+
# Only install test tools in debug build or eng build.
ifneq ($(filter userdebug eng,$(TARGET_BUILD_VARIANT)),)
PRODUCT_PACKAGES += thruster_test
diff --git a/conf/ueventd.rc b/conf/ueventd.rc
index 88ee00b..2f03009 100644
--- a/conf/ueventd.rc
+++ b/conf/ueventd.rc
@@ -209,3 +209,7 @@
# Thrusters
/dev/thruster* 0600 system system
+
+# Raw HID devices
+/dev/hidraw* 0660 system system
+
diff --git a/sepolicy/sensor_hal.te b/sepolicy/sensor_hal.te
index 0797253..22a4208 100644
--- a/sepolicy/sensor_hal.te
+++ b/sepolicy/sensor_hal.te
@@ -52,6 +52,9 @@
# Allow sensor HAL to read thruster state.
allow hal_sensors_default thruster_state:file r_file_perms;
+# Allow access for dynamic sensor properties.
+get_prop(hal_sensors_default, vendor_dynamic_sensor_prop)
+
+# Allow access to raw HID devices for dynamic sensors.
+allow hal_sensors_default hidraw_device:chr_file rw_file_perms;
+
#
# Thruster sensor enforcements.
#
diff --git a/sepolicy/device.te b/sepolicy/device.te
index bc3c947..bad0be0 100644
--- a/sepolicy/device.te
+++ b/sepolicy/device.te
@@ -55,3 +55,7 @@
# Thruster
type thruster_device, dev_type;
+
+# Raw HID device
+type hidraw_device, dev_type;
+
diff --git a/sepolicy/property.te b/sepolicy/property.te
index 4b671a4..bb0894f 100644
--- a/sepolicy/property.te
+++ b/sepolicy/property.te
@@ -49,3 +49,7 @@
# Thruster
vendor_internal_prop(vendor_thruster_debug_prop)
+
+# Dynamic sensor
+vendor_internal_prop(vendor_dynamic_sensor_prop)
+
diff --git a/sepolicy/file_contexts b/sepolicy/file_contexts
index bc03a78..ff401dc 100644
--- a/sepolicy/file_contexts
+++ b/sepolicy/file_contexts
@@ -441,3 +441,7 @@
/dev/thruster-fuel u:object_r:thruster_device:s0
/dev/thruster-output u:object_r:thruster_device:s0
/dev/thruster-telemetry u:object_r:thruster_device:s0
+
+# Raw HID device
+/dev/hidraw[0-9]* u:object_r:hidraw_device:s0
+
diff --git a/sepolicy/property_contexts b/sepolicy/property_contexts
index 5d2f018..18a6059 100644
--- a/sepolicy/property_contexts
+++ b/sepolicy/property_contexts
@@ -104,3 +104,7 @@
# Thruster
vendor.thruster.debug u:object_r:vendor_thruster_debug_prop:s0
+
+# Dynamic sensor
+vendor.dynamic_sensor. u:object_r:vendor_dynamic_sensor_prop:s0
+
acme-co$
```
Once the file modifications are made, rebuild and flash. The dynamic sensor HAL
should be initialized and appear in the sensor service.
```shell
acme-co$ make -j28 && fastboot flashall
.
.
.
acme-co$ adb logcat -d | grep DynamicSensorHal
12-15 18:18:45.735 791 791 D DynamicSensorHal: DynamicSensorsSubHal::getSensorsList_2_1 invoked.
12-15 18:18:47.474 791 791 D DynamicSensorHal: DynamicSensorsSubHal::initialize invoked.
acme-co$ adb shell dumpsys sensorservice | grep Dynamic
0000000000) Dynamic Sensor Manager | Google | ver: 1 | type: android.sensor.dynamic_sensor_meta(32) | perm: n/a | flags: 0x00000007
Dynamic Sensor Manager (handle=0x00000000, connections=1)
Dynamic Sensor Manager 0x00000000 | status: active | pending flush events 0
acme-co$ adb logcat -c
acme-co$
```
When a dynamic sensor is paired with the device (e.g., Bluetooth rocket buds),
it will appear in the sensor service.
```shell
acme-co$ adb logcat -d | grep "DynamicSensorHal\|hidraw\|Rocket"
12-15 18:19:55.268 157 157 I hid-generic 0003: 1234:5678.0001: hidraw0: BLUETOOTH HID v0.00 Device [RocketBuds] on
12-15 18:19:55.235 791 809 E DynamicSensorHal: return 1 sensors
12-15 18:19:56.239 1629 1787 I SensorService: Dynamic sensor handle 0x1 connected, type 65536, name RocketBuds
acme-co$ adb shell dumpsys sensorservice | grep Rocket
0x00000001) RocketBuds | BLUETOOTH 1234:1234 | ver: 1 | type: com.google.hardware.sensor.hid_dynamic.headtracker(65536) | perm: n/a | flags: 0x00000020
acme-co$
```
|
