init-debug.rc: add runtime mmc max speed property actors

persist.mmc.max_read_speed  - KB/s speed cap
persist.mmc.max_write_speed - KB/s speed cap
persist.mmc.cache_size      - MB of high-speed on-device write cache

device default directly to associated /sys/block/mmcblk0/ attributes,
not delivered on "user" builds.

Bug: 26976972
Change-Id: Ic82b9614489b6406ce830d127c85affc9095e256
diff --git a/rootdir/Android.mk b/rootdir/Android.mk
index 895a25d..d90f988 100644
--- a/rootdir/Android.mk
+++ b/rootdir/Android.mk
@@ -12,6 +12,18 @@
 include $(BUILD_PREBUILT)
 
 #######################################
+# init-debug.rc
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := init-debug.rc
+LOCAL_SRC_FILES := $(LOCAL_MODULE)
+LOCAL_MODULE_CLASS := ETC
+LOCAL_MODULE_TAGS := debug
+LOCAL_MODULE_PATH := $(TARGET_OUT_ETC)/init
+
+include $(BUILD_PREBUILT)
+
+#######################################
 # asan.options
 ifneq ($(filter address,$(SANITIZE_TARGET)),)
 include $(CLEAR_VARS)
diff --git a/rootdir/init-debug.rc b/rootdir/init-debug.rc
new file mode 100644
index 0000000..435d4cb
--- /dev/null
+++ b/rootdir/init-debug.rc
@@ -0,0 +1,8 @@
+on property:persist.mmc.max_read_speed=*
+    write /sys/block/mmcblk0/max_read_speed ${persist.mmc.max_read_speed}
+
+on property:persist.mmc.max_write_speed=*
+    write /sys/block/mmcblk0/max_write_speed ${persist.mmc.max_write_speed}
+
+on property:persist.mmc.cache_size=*
+    write /sys/block/mmcblk0/cache_size ${persist.mmc.cache_size}