From 5b76bfc0d04cd220b055052f28f8b304c1c0b188 Mon Sep 17 00:00:00 2001
From: sqian <shuoq@google.com>
Date: Wed, 7 Nov 2018 16:46:07 -0800
Subject: [PATCH] Introduce getRssi() in CellSignalStrengthLte

Previous people designed that the lte signal strength from HAL is rssi
in ASU, but the new need of getRssi() API requires dBm unit.

Bug: 113074174
Test: Treehugger
Change-Id: I2982365a2e7fe1a56a393d123b9b0a30807d4d15
---
 api/current.txt                               |  1 +
 .../telephony/CellSignalStrengthLte.java      | 45 +++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/api/current.txt b/api/current.txt
index f1700f25121e9..2995d40970fec 100755
--- a/api/current.txt
+++ b/api/current.txt
@@ -42281,6 +42281,7 @@ package android.telephony {
     method public int getLevel();
     method public int getRsrp();
     method public int getRsrq();
+    method public int getRssi();
     method public int getRssnr();
     method public int getTimingAdvance();
     method public void writeToParcel(android.os.Parcel, int);
diff --git a/telephony/java/android/telephony/CellSignalStrengthLte.java b/telephony/java/android/telephony/CellSignalStrengthLte.java
index d6856b397a00a..280a8d2a00200 100644
--- a/telephony/java/android/telephony/CellSignalStrengthLte.java
+++ b/telephony/java/android/telephony/CellSignalStrengthLte.java
@@ -31,6 +31,25 @@ public final class CellSignalStrengthLte extends CellSignalStrength implements P
     private static final String LOG_TAG = "CellSignalStrengthLte";
     private static final boolean DBG = false;
 
+    /**
+     * Indicates the unknown or undetectable RSSI value in ASU.
+     *
+     * Reference: TS 27.007 8.5 - Signal quality +CSQ
+     */
+    private static final int SIGNAL_STRENGTH_LTE_RSSI_ASU_UNKNOWN = 99;
+    /**
+     * Indicates the maximum valid RSSI value in ASU.
+     *
+     * Reference: TS 27.007 8.5 - Signal quality +CSQ
+     */
+    private static final int SIGNAL_STRENGTH_LTE_RSSI_VALID_ASU_MAX_VALUE = 31;
+    /**
+     * Indicates the minimum valid RSSI value in ASU.
+     *
+     * Reference: TS 27.007 8.5 - Signal quality +CSQ
+     */
+    private static final int SIGNAL_STRENGTH_LTE_RSSI_VALID_ASU_MIN_VALUE = 0;
+
     @UnsupportedAppUsage
     private int mSignalStrength;
     @UnsupportedAppUsage
@@ -141,6 +160,19 @@ public final class CellSignalStrengthLte extends CellSignalStrength implements P
         return mRsrq;
     }
 
+    /**
+     * Get Received Signal Strength Indication (RSSI) in dBm
+     *
+     * The value range is [-113, -51] inclusively or {@link CellInfo#UNAVAILABLE} if unavailable.
+     *
+     * Reference: TS 27.007 8.5 Signal quality +CSQ
+     *
+     * @return the RSSI if available or {@link CellInfo#UNAVAILABLE} if unavailable.
+     */
+    public int getRssi() {
+        return convertRssiAsuToDBm(mSignalStrength);
+    }
+
     /**
      * Get reference signal signal-to-noise ratio
      *
@@ -309,4 +341,17 @@ public final class CellSignalStrengthLte extends CellSignalStrength implements P
     private static void log(String s) {
         Rlog.w(LOG_TAG, s);
     }
+
+    private static int convertRssiAsuToDBm(int rssiAsu) {
+        if (rssiAsu != SIGNAL_STRENGTH_LTE_RSSI_ASU_UNKNOWN
+                && (rssiAsu < SIGNAL_STRENGTH_LTE_RSSI_VALID_ASU_MIN_VALUE
+                || rssiAsu > SIGNAL_STRENGTH_LTE_RSSI_VALID_ASU_MAX_VALUE)) {
+            Rlog.e(LOG_TAG, "convertRssiAsuToDBm: invalid RSSI in ASU=" + rssiAsu);
+            return CellInfo.UNAVAILABLE;
+        }
+        if (rssiAsu == SIGNAL_STRENGTH_LTE_RSSI_ASU_UNKNOWN) {
+            return CellInfo.UNAVAILABLE;
+        }
+        return -113 + (2 * rssiAsu);
+    }
 }