[libhealthd] Proper battery paths

* 4.4 introduces a new daemon, healthd, that handles battery status
    - resides in: /system/core/healthd
    - BatteryMonitor.cpp iterates through all the *directories* under
      /sys/class/power_supply looking for a file called 'type'
    - if the type == Battery, it assumes this is the location for the
      battery stats for the device. Only the first directory that matches
      this criteria is used.
    - on msm8660/d2/jf/s2 kernels, this search results in:
      /sys/class/power_supply/fuelgauge.
    - To determine capacity, healthd looks at the contents of the
      'capacity' file under this discovered base path. This results
      in /sys/class/power_supply/fuelgauge/capacity on msm8660/d2/jf/s2
      kernels.
    - Unfortunately, this is the wrong path. The capacity file at this
      location returns a large negative number.
    - Other paths like status, voltage_now, and present are also
      incorrectly determined.
  * For comparison, in 4.3 battery statistics gathering was handled by
    frameworks/base/services/jni/com_android_server_BatteryService.cpp
    - BatteryService does a similar search for a file called 'type' with
      the contents of 'Battery'
    - But the search logic is different here: it takes the *last* path that
      matches the criteria.
    - This results in the correct /sys/class/power_supply/battery
  * This patch overrides the discovery mechanism for battery status completely.

Change-Id: I4579c92bba5596eef4dac67b8c0687be50a1d2f5

BoardCommonConfig.mk

@@ -168,5 +168,8 @@ BOARD_CHARGER_RES := device/samsung/galaxys2-common/res/charger
 
 BOARD_CUSTOM_BOOTIMG_MK := device/samsung/galaxys2-common/shbootimg.mk
 
+# Override healthd HAL
+BOARD_HAL_STATIC_LIBRARIES := libhealthd.exynos4
+
 # Use the non-open-source parts, if they're present
 -include vendor/samsung/galaxys2-common/BoardConfigVendor.mk

libhealthd/Android.mk

@@ -0,0 +1,22 @@
+# Copyright (C) 2013 The Android Open Source Project
+# Copyright (C) 2013 The CyanogenMod Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := healthd_board_exynos4.cpp
+LOCAL_MODULE := libhealthd.exynos4
+LOCAL_C_INCLUDES := system/core/healthd
+include $(BUILD_STATIC_LIBRARY)

libhealthd/healthd_board_exynos4.cpp

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ * Copyright (C) 2013 The CyanogenMod Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <healthd.h>
+
+void
+healthd_board_init(struct healthd_config *config)
+{
+    config->batteryCapacityPath    = "/sys/class/power_supply/battery/capacity";
+    config->batteryStatusPath      = "/sys/class/power_supply/battery/status";
+    config->batteryVoltagePath     = "/sys/class/power_supply/battery/voltage_now";
+    config->batteryCurrentNowPath  = "/sys/class/power_supply/battery/batt_current_now";
+    config->batteryPresentPath     = "/sys/class/power_supply/battery/present";
+    config->batteryHealthPath      = "/sys/class/power_supply/battery/health";
+    config->batteryTemperaturePath = "/sys/class/power_supply/battery/temp";
+    config->batteryTechnologyPath  = "/sys/class/power_supply/battery/technology";
+    // others use defaults
+}
+
+int
+healthd_board_battery_update(struct android::BatteryProperties *props)
+{
+    // return 0 to log periodic polled battery status to kernel log
+    return 0;
+}