health: add README.
Test: none
Bug: 63702641
Change-Id: I1d23c0cdf56516585e7c6dd0db577784baa7b74e
diff --git a/health/2.0/utils/README b/health/2.0/utils/README
new file mode 100644
index 0000000..1d5c27f
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+++ b/health/2.0/utils/README
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+* libhealthhalutils
+
+A convenience library for (hwbinder) clients of health HAL to choose between
+the "default" instance (served by vendor service) or "backup" instance (served
+by healthd). C++ clients of health HAL should use this library instead of
+calling IHealth::getService() directly.
+
+Its Java equivalent can be found in BatteryService.HealthServiceWrapper.
+
+* libhealthservice
+
+Common code for all (hwbinder) services of the health HAL, including healthd and
+vendor health service android.hardware.health@2.0-service(.<vendor>). main() in
+those binaries calls health_service_main() directly.
+
+* libhealthstoragedefault
+
+Default implementation for storage related APIs for (hwbinder) services of the
+health HAL. If an implementation of the health HAL do not wish to provide any
+storage info, include this library. Otherwise, it should implement the following
+two functions:
+
+void get_storage_info(std::vector<struct StorageInfo>& info) {
+ // ...
+}
+void get_disk_stats(std::vector<struct DiskStats>& stats) {
+ // ...
+}