Android4.4 RIL软件框架
本文主要对android4.4 RIL的telephony与modem的命令交互流程进行分析，当然本文不是重点介绍telephony。
telephony涉及具体业务逻辑内容比较多，包括sim、dail、sms、network等等，以后会针对这些内容学习分析。
RIL在Android体系中的位置：
(A) 应用层发起访问modem的请求
(B) RILD进程
(A) 应用层发起访问modem的请求
frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java中的类RIL，提供了一系
列的接口给上层应用调用，以访问modem。当然这些接口并不是直接给APP使用，而是由framework中sim、dail、
sms、network等相关服务调用。
如: 以查询SIM卡状态getIccCardStatus()为例，该API为UiccController模块所调用：
完整的SIM卡请求log:
10-11 12:21:43.630 D/RILJ ( 1833): [3653]> GET_SIM_STATUS
10-11 12:21:43.630 D/RILC ( 1286): [0005]> GET_SIM_STATUS
10-11 12:21:43.630 D/RILC ( 1286): onRequest: GET_SIM_STATUS
10-11 12:21:43.630 D/ATC ( 1286): AT> AT+CPIN?
10-11 12:21:43.640 D/ATC ( 1286): AT< +CPIN: READY
10-11 12:21:43.640 D/ATC ( 1286): AT< OK
10-11 12:21:43.640 D/RILC ( 1286): [0005]< GET_SIM_STATUS {[app_type=1,app_state=5,perso_substate=2,aid_ptr=(null),app_label_ptr=(null),pin1_replaced=0,pin1=0,pin2=0],}
10-11 12:21:43.640 D/RILJ ( 1833): [3653]< GET_SIM_STATUS IccCardState {CARDSTATE_PRESENT,PINSTATE_UNKNOWN,num_apps=1,gsm_id=0{APPTYPE_SIM,APPSTATE_READY},cdma_id=8,ims_id=8}
发起请求：
frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java
@Override public void getIccCardStatus(Message result) { //Note: This RIL request has not been renamed to ICC, // but this request is also valid for SIM and RUIM RILRequest rr = RILRequest.obtain(RIL_REQUEST_GET_SIM_STATUS, result); /* 获取一个RILRequest */ if (RILJ_LOGD) riljLog(rr.serialString() + "> " + requestToString(rr.mRequest)); /* 参考log：[3653]> GET_SIM_STATUS */ send(rr); /* 发送请求 */ }
RILRequest.obtain是从内存池获取一个RILRequest实例，并初始化：
frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java
class RILRequest { static final String LOG_TAG = "RilRequest"; ... ... static RILRequest obtain(int request, Message result) { RILRequest rr = null; synchronized(sPoolSync) { /* 从内存池中取出一个RILRequest对象*/ if (sPool != null) { rr = sPool; sPool = rr.mNext; rr.mNext = null; sPoolSize--; } } if (rr == null) { /* 如果内存池中没有，则实例化一个 */ rr = new RILRequest(); } rr.mSerial = sNextSerial.getAndIncrement(); /* 获取串号，并且+1 */ rr.mRequest = request; /* 对应RIL_REQUEST_*请求 */ rr.mResult = result; rr.mParcel = Parcel.obtain(); /* 初始化一个Parcel，用于封包以发送给底层RILD */ if (result != null && result.getTarget() == null) { throw new NullPointerException("Message target must not be null"); } // first elements in any RIL Parcel rr.mParcel.writeInt(request); /* 每个RIL Parcel最开始也最基本的两个元素 */ rr.mParcel.writeInt(rr.mSerial); return rr; /* 返回这个从内存池中获取的实例 */ } ... ... String serialString() { //Cheesy way to do %04d StringBuilder sb = new StringBuilder(8); /* 创建一个StringBuilder实例用于操作字符串 */ String sn; long adjustedSerial = (((long)mSerial) - Integer.MIN_VALUE)%10000; sn = Long.toString(adjustedSerial); /* 把数值转换成字符串 */ //sb.append("J["); sb.append('['); for (int i = 0, s = sn.length() ; i < 4 - s; i++) { sb.append('0'); } sb.append(sn); sb.append(']'); return sb.toString(); /* 转换出来的字符串格式: [xxxx] */ } ... ... }
send(rr)发送请求到服务端：
frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java
private void send(RILRequest rr) { Message msg; ... ... msg = mSender.obtainMessage(EVENT_SEND, rr); /* 发送EVENT_SEND时间，时间参数为RILRequest */ acquireWakeLock(); /* 获取wakelock，禁止进入休眠 */ msg.sendToTarget(); /* message从handler类获取，从而可以直接向该handler对象发送消息。target就是创建message的handler */ }
实际上telephony无法直接与modem通讯，由于每个厂商的modem都不一样，modem存在于系统中的方式
也不一样，如：有的CPU芯片厂商的modem是以一个CP核的方式集成在基带上（高通、展讯等），有的CPU芯
片（Exynos 4412等）需要通过串口/USB外接modem模块，如：BC72 LTE模块等。
send(rr)向RILD发送请求，这里涉及一个进程间通信问题，而且Java侧与C++侧的进程通讯，当然这里并没
有用Android开发的朋友都熟悉的Bind，而是socket。
telephony/Java侧RIL命令交互的处理，暂且称为RILJ。
RILJ作为socket的客户端，RILD（rild进程）作为服务端，后面会分析rild进程。
socket客户端的创建：
frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java
public RIL(Context context, int preferredNetworkType, int cdmaSubscription) { ... ... mSenderThread = new HandlerThread("RILSender"); /* 创建RILSender线程 */ mSenderThread.start(); Looper looper = mSenderThread.getLooper(); mSender = new RILSender(looper); ConnectivityManager cm = (ConnectivityManager)context.getSystemService( Context.CONNECTIVITY_SERVICE); if (cm.isNetworkSupported(ConnectivityManager.TYPE_MOBILE) == false) { riljLog("Not starting RILReceiver: wifi-only"); } else { riljLog("Starting RILReceiver"); mReceiver = new RILReceiver(); mReceiverThread = new Thread(mReceiver, "RILReceiver"); /* 创建RILReceiver线程 */ mReceiverThread.start(); ... ... } ... ... } class RILReceiver implements Runnable { byte[] buffer; RILReceiver() { /* 构造时，分配一个数组 */ buffer = new byte[RIL_MAX_COMMAND_BYTES]; } @Override public void run() { /* 循环读取从RILD返回或主动上报的数据 */ int retryCount = 0; try {for (;;) { LocalSocket s = null; LocalSocketAddress l; try { s = new LocalSocket(); /* 创建一个socket客户端 */ l = new LocalSocketAddress(SOCKET_NAME_RIL, LocalSocketAddress.Namespace.RESERVED); s.connect(l); /* 连接服务器 */ } ... ... } ... ... try { InputStream is = mSocket.getInputStream(); /* 循环读取socket的数据 */ for (;;) { Parcel p; length = readRilMessage(is, buffer); /* 解析socket数据 */ if (length < 0) { // End-of-stream reached break; } p = Parcel.obtain(); /* 获取一个Parcel */ p.unmarshall(buffer, 0, length); /* 读取出来的就是之前序列化的byte数组，所以要进行一个反序列化操作 */ p.setDataPosition(0); /* 从buffer转换到Parcel之后，需要将指针手动指向到最初的位置 */ //Rlog.v(RILJ_LOG_TAG, "Read packet: " + length + " bytes"); processResponse(p); p.recycle(); /* 数据处理完后，需要回收Parcel的内存 */ } } ... ... }
RILReceiver线程创建socket客户端，连接服务端，然后进入等待服务端的processResponse消息处理循环，RILJ
接收到RILD回复的response返回RIL请求的发起者，以getIccCardStatus(Message result)为例，processResponse(p)
会把DRILD的response返回给UiccController
frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java
private static int readRilMessage(InputStream is, byte[] buffer) throws IOException { int countRead; int offset; int remaining; int messageLength; // First, read in the length of the message offset = 0; remaining = 4; do { countRead = is.read(buffer, offset, remaining); /* 读出消息的4字节长度 */ if (countRead < 0 ) { Rlog.e(RILJ_LOG_TAG, "Hit EOS reading message length"); return -1; } offset += countRead; remaining -= countRead; } while (remaining > 0); messageLength = ((buffer[0] & 0xff) << 24) /* 获取长度 */ | ((buffer[1] & 0xff) << 16) | ((buffer[2] & 0xff) << 8) | (buffer[3] & 0xff); // Then, re-use the buffer and read in the message itself offset = 0; remaining = messageLength; do { countRead = is.read(buffer, offset, remaining); /* 读取剩余的数据 */ if (countRead < 0 ) { Rlog.e(RILJ_LOG_TAG, "Hit EOS reading message. messageLength=" + messageLength + " remaining=" + remaining); return -1; } offset += countRead; remaining -= countRead; } while (remaining > 0); return messageLength; } private void processResponse (Parcel p) { int type; type = p.readInt(); /* 从RILD返回的数据第一个字节，表示请求的返回类型:RESPONSE_UNSOLICITED/RESPONSE_SOLICITED */ if (type == RESPONSE_UNSOLICITED) { processUnsolicited (p); /* 主动上报 */ } else if (type == RESPONSE_SOLICITED) { RILRequest rr = processSolicited (p); /* 普通请求对应的同步上报 */ if (rr != null) { rr.release(); /* 释放对应的RILRequest内存和wakelock */ decrementWakeLock(); } } }
RILD的response一般有两种，一种是RILJ普通请求,RILD对RILJ请求的response (RESPONSE_SOLICITED)，另一种是RILD主动上报的
response (RESPONSE_UNSOLICITED), processResponse (Parcel p)分别对这两种情况的response进行处理。
frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java
private RILRequest processSolicited (Parcel p) { int serial, error; boolean found = false; serial = p.readInt(); /* 串号，也就是token */ error = p.readInt(); /* 错误码 */ RILRequest rr; rr = findAndRemoveRequestFromList(serial); /* 根据taken取出对应的RILRequest */ ... ... */ case RIL_REQUEST_GET_SIM_STATUS: ret = responseIccCardStatus(p); break; ... ... if (rr.mResult != null) { AsyncResult.forMessage(rr.mResult, ret, null); /* 把rr.mResult存到AsyncResult.userObj,并把rr.mResult.obj转换为AsyncResult */ rr.mResult.sendToTarget(); /* msg发送到对应的target(Handler) */ } ... ... } private Object responseIccCardStatus(Parcel p) { IccCardApplicationStatus appStatus; ... ... appStatus = new IccCardApplicationStatus(); ... ... return cardStatus; }
回到刚才send(rr)，send(rr)并不是直接发送到socket服务端RILD，而是通过一个Message发送到RILSender线程，
在handleMessage中，把请求发到socket服务端RILD。
frameworks/opt/telephony/src/java/com/android/internal/telephony/RIL.java
class RILSender extends Handler implements Runnable { /* 继承Handler，实现Runnable */ public RILSender(Looper looper) { super(looper); } ... ... //***** Handler implementation @Override public void handleMessage(Message msg) { /* 继承Handler的handleMessage */ RILRequest rr = (RILRequest)(msg.obj); /* Maessage中携带的RILRequest对象 */ RILRequest req = null; switch (msg.what) { case EVENT_SEND: /* 发送RIL请求事件 */ try { LocalSocket s; s = mSocket; /* RILReceiver中创建的用于与RILD通讯的socket */ ... ... synchronized (mRequestList) { /* 多线程保护操作mRequestList */ mRequestList.append(rr.mSerial, rr); /* 把接受到的RILRequest和对应的串号，存到mRequestList数据 */ } byte[] data; data = rr.mParcel.marshall(); /* 把Parcel中的数据转换为byte数据 */ rr.mParcel.recycle(); /* Parcel的内存回收 */ rr.mParcel = null; ... ... // parcel length in big endian dataLength[0] = dataLength[1] = 0; /* RIL请求包的大小为4个字节 */ dataLength[2] = (byte)((data.length >> 8) & 0xff); dataLength[3] = (byte)((data.length) & 0xff); //Rlog.v(RILJ_LOG_TAG, "writing packet: " + data.length + " bytes"); s.getOutputStream().write(dataLength); /* 把包大小和包数据发送出去 */ s.getOutputStream().write(data); } catch (IOException ex) { Rlog.e(RILJ_LOG_TAG, "IOException", ex); req = findAndRemoveRequestFromList(rr.mSerial); /* 如果出现异常，则把串号对应的RILRequest从mRequestList中删除 */ // make sure this request has not already been handled, // eg, if RILReceiver cleared the list. if (req != null) { rr.onError(RADIO_NOT_AVAILABLE, null); rr.release(); decrementWakeLock(); } } ... ... } } }
(B) RILD进程
RILD作为一个独立的进程，telephony与modem之间的通讯通道。抽象出一些接口以适配不同的modem厂商，无需关心具体的
硬件操作，或者以哪种形式存存在于系统(modem作为CP集成于CPU或CPU通过串口/USB连接，如: BC72 LTE模块)。因为这些接口
由厂商去实现具体的硬件操作细节，这些接口都在libreference-ril中，在Android中使用BC72 LTE模块，只要移植
libreference-ril就行。
1. RILD的启动
RILD有init进程直接启动，启动后就监听RILJ客户端，等待RILJ连接请求。
device/samsung/smdk4x12/conf/init.smdk4x12.rc
service ril-daemon /system/bin/rild -l /system/lib/libreference-ril.so class main socket rild stream 660 root radio socket rild-debug stream 660 radio system user root
hardware/ril/rild/rild.c为RILD进程入口：
hardware/ril/rild/rild.c
int main(int argc, char **argv) { ... ... dlHandle = dlopen(rilLibPath, RTLD_NOW); /* 打开/system/lib/libreference-ril.so */ if (dlHandle == NULL) { RLOGE("dlopen failed: %s", dlerror()); exit(-1); } RIL_startEventLoop(); /* 创建eventLoop线程, 在ril_event_loop()中监听多路IO的事件，如主动唤醒事件(pipe)、RILJ的请求等 */ /* 获取/system/lib/libreference-ril.so中RIL_Init函数指针 */ rilInit = (const RIL_RadioFunctions *(*)(const struct RIL_Env *, int, char **))dlsym(dlHandle, "RIL_Init"); if (rilInit == NULL) { RLOGE("RIL_Init not defined or exported in %s\n", rilLibPath); exit(-1); } if (hasLibArgs) { rilArgv = argv + i - 1; argc = argc -i + 1; } else { static char * newArgv[MAX_LIB_ARGS]; static char args[PROPERTY_VALUE_MAX]; rilArgv = newArgv; property_get(LIB_ARGS_PROPERTY, args, ""); argc = make_argv(args, rilArgv); } // Make sure there's a reasonable argv[0] rilArgv[0] = argv[0]; funcs = rilInit(&s_rilEnv, argc, rilArgv); /* 初始化Vender RIL */ RIL_register(funcs); /* 注册RIL */ ... ... }
hardware/ril/libril/ril.cpp
extern "C" void RIL_startEventLoop(void) { ... ... ret = pthread_create(&s_tid_dispatch, &attr, eventLoop, NULL); /* 创建eventLoop线程 */ ... ... } static void * eventLoop(void *param) { int ret; int filedes[2]; ril_event_init(); /* 初始化事件链表，timer_list，pending_list, watch_table */ pthread_mutex_lock(&s_startupMutex); s_started = 1; pthread_cond_broadcast(&s_startupCond); pthread_mutex_unlock(&s_startupMutex); ret = pipe(filedes); /* 创建一个pipe，用于每次添加一个新事件时，唤醒selet()返回，更新fd_set使select监听新的事件 */ if (ret < 0) { RLOGE("Error in pipe() errno:%d", errno); return NULL; } s_fdWakeupRead = filedes[0]; /* filedes[0]用于读pipe， filedes[1]用于写pipe */ s_fdWakeupWrite = filedes[1]; fcntl(s_fdWakeupRead, F_SETFL, O_NONBLOCK); /* 以非阻塞的方式读pipe */ ril_event_set (&s_wakeupfd_event, s_fdWakeupRead, true, /* 读pipe描述符绑定到s_wakeupfd_event事件，指定回调processWakeupCallback */ processWakeupCallback, NULL); rilEventAddWakeup (&s_wakeupfd_event); /* 添加s_wakeupfd_event事件到watch_table,更新readFds集合，使select监听该事件，并触发该事件 */ // Only returns on error ril_event_loop(); /* 进入多路IO事件监听循环 */ RLOGE ("error in event_loop_base errno:%d", errno); // kill self to restart on error kill(0, SIGKILL); return NULL; }
main函数主要启动eventLoop线程，在ril_event_loop()中监听多路IO的事件，如主动唤醒事件(pipe)、RILJ的请求等，
注册vendor RIL接口（libreference-ril）
注意这里pipe的主要作用是唤醒select返回，因为每次动态的添加一个事件，都要更新readFds集合，方便select监听
集合中新的IO。
rilEventAddWakeup()添加新事件后，都会触发select返回
hardware/ril/libril/ril.cpp
static void rilEventAddWakeup(struct ril_event *ev) { ril_event_add(ev); /* 添加事件 */ triggerEvLoop(); /* 触发事件, 每添加一个事件，都通过写pipe唤醒select，以更新多路IO集合，使能够监听该事件 */ }
hardware/ril/libril/ril_event.cpp
void ril_event_add(struct ril_event * ev) { dlog("~~~~ +ril_event_add ~~~~"); MUTEX_ACQUIRE(); for (int i = 0; i < MAX_FD_EVENTS; i++) { if (watch_table[i] == NULL) { watch_table[i] = ev; /* 将新事件添加到watch_table */ ev->index = i; dlog("~~~~ added at %d ~~~~", i); dump_event(ev); FD_SET(ev->fd, &readFds); /* 更新readFds集合 */ if (ev->fd >= nfds) nfds = ev->fd+1; /* 更新nfds */ dlog("~~~~ nfds = %d ~~~~", nfds); break; } } MUTEX_RELEASE(); dlog("~~~~ -ril_event_add ~~~~"); }
hardware/ril/libril/ril.cpp
static void triggerEvLoop() { int ret; if (!pthread_equal(pthread_self(), s_tid_dispatch)) { /* trigger event loop to wakeup. No reason to do this, * if we're in the event loop thread */ do { ret = write (s_fdWakeupWrite, " ", 1); /* 向pipe写入一个" "，以唤醒select */ } while (ret < 0 && errno == EINTR); } }
在ril_event_loop()接收到事件或socket客户端RILJ发过来的请求后，firePending()根据事件请求，调用相应的处理函数
hardware/ril/libril/ril_event.cpp
void ril_event_loop() { int n; fd_set rfds; struct timeval tv; struct timeval * ptv; for (;;) { // make local copy of read fd_set memcpy(&rfds, &readFds, sizeof(fd_set)); if (-1 == calcNextTimeout(&tv)) { /* 计算timer_list链表中每个事件对应的超时时间 */ // no pending timers; block indefinitely dlog("~~~~ no timers; blocking indefinitely ~~~~"); ptv = NULL; } else { dlog("~~~~ blocking for %ds + %dus ~~~~", (int)tv.tv_sec, (int)tv.tv_usec); ptv = &tv; } printReadies(&rfds); n = select(nfds, &rfds, NULL, NULL, ptv); /* 等待readFds集合中的事件唤醒 */ printReadies(&rfds); dlog("~~~~ %d events fired ~~~~", n); if (n < 0) { if (errno == EINTR) continue; RLOGE("ril_event: select error (%d)", errno); // bail? return; } // Check for timeouts processTimeouts(); /* 检查timer_list链表中是否有事件已经超时 */ // Check for read-ready processReadReadies(&rfds, n); /* 从watch_table中取出监听到的事件, 并添加到pending_list链表 */ // Fire away firePending(); /* 从pending_list依次取出事件,并执行该事件的回调 */ } } static void processTimeouts() { dlog("~~~~ +processTimeouts ~~~~"); MUTEX_ACQUIRE(); struct timeval now; struct ril_event * tev = timer_list.next; struct ril_event * next; getNow(&now); // walk list, see if now >= ev->timeout for any events /* 检查timer_list链表中是否有事件已经超时 */ dlog("~~~~ Looking for timers <= %ds + %dus ~~~~", (int)now.tv_sec, (int)now.tv_usec); while ((tev != &timer_list) && (timercmp(&now, &tev->timeout, >))) { // Timer expired dlog("~~~~ firing timer ~~~~"); next = tev->next; removeFromList(tev); /* 将该超时移出链表 */ addToList(tev, &pending_list); /* 并且将该超时添加到pending链表 */ tev = next; /* 指针指向下一个超时 */ } MUTEX_RELEASE(); dlog("~~~~ -processTimeouts ~~~~"); } static void processReadReadies(fd_set * rfds, int n) { dlog("~~~~ +processReadReadies (%d) ~~~~", n); MUTEX_ACQUIRE(); for (int i = 0; (i < MAX_FD_EVENTS) && (n > 0); i++) { struct ril_event * rev = watch_table[i]; if (rev != NULL && FD_ISSET(rev->fd, rfds)) { /* 从watch_table中取出监听到的事件 */ addToList(rev, &pending_list); /* 并把该事件加入pending_list链表 */ if (rev->persist == false) { /* 如果该事件不需要处理，则移出removeWatch */ removeWatch(rev, i); } n--; } } MUTEX_RELEASE(); dlog("~~~~ -processReadReadies (%d) ~~~~", n); } static void firePending() { dlog("~~~~ +firePending ~~~~"); struct ril_event * ev = pending_list.next; while (ev != &pending_list) { /* 从pending_list依次取出事件 */ struct ril_event * next = ev->next; removeFromList(ev); ev->func(ev->fd, 0, ev->param); /* 并执行该事件的回调 */ ev = next; } dlog("~~~~ -firePending ~~~~"); }
上面分析了RIL_startEventLoop()的事件流程，简单总结就是根据事件调用该事件的处理函数。
到这里还没说到怎样创建socket服务端的，回到mian()，funcs = rilInit(&s_rilEnv, argc, rilArgv);
初始化了libreference-ril,RIL_register(funcs);注册了厂商须实现的相关接口，创建socket服务端的，
并监听客户端连接，一旦连接，则开始等待读取客户端发过来的请求。
hardware/ril/libril/ril.cpp
extern "C" void RIL_register (const RIL_RadioFunctions *callbacks) { ... ... s_fdListen = android_get_control_socket(SOCKET_NAME_RIL); /* 创建socket服务端，用于与RILJ通信 */ if (s_fdListen < 0) { RLOGE("Failed to get socket '" SOCKET_NAME_RIL "'"); exit(-1); } ret = listen(s_fdListen, 4); /* 监听RILJ */ if (ret < 0) { RLOGE("Failed to listen on control socket '%d': %s", s_fdListen, strerror(errno)); exit(-1); } /* note: non-persistent so we can accept only one connection at a time */ ril_event_set (&s_listen_event, s_fdListen, false, /* 设置一个监听事件s_listen_event，一旦与RILJ建立连 */ listenCallback, NULL); /* 则进入listenCallback，等待读取RILJ发送数据 */ rilEventAddWakeup (&s_listen_event); /* 添加s_listen_event到watch_table, 唤醒select */ ... ... } static void listenCallback (int fd, short flags, void *param) { ... ... s_fdCommand = accept(s_fdListen, (sockaddr *) &peeraddr, &socklen); /* 接受RILJ客户端的连接 */ ... ... err = getsockopt(s_fdCommand, SOL_SOCKET, SO_PEERCRED, &creds, &szCreds); ret = fcntl(s_fdCommand, F_SETFL, O_NONBLOCK); /* 非阻塞方式读写socket */ if (ret < 0) { RLOGE ("Error setting O_NONBLOCK errno:%d", errno); } RLOGI("libril: new connection"); p_rs = record_stream_new(s_fdCommand, MAX_COMMAND_BYTES); /* 创建一个stream用于缓存读socket的数据 */ ril_event_set (&s_commands_event, s_fdCommand, 1, /* 设置s_commands_event，processCommandsCallback循环读取socket的数据 */ processCommandsCallback, p_rs); rilEventAddWakeup (&s_commands_event); /* 添加s_commands_event事件，唤醒select */ onNewCommandConnect(); /* 通知RILJ已建立连接 */ } static void processCommandsCallback(int fd, short flags, void *param) { ... ... for (;;) { /* loop until EAGAIN/EINTR, end of stream, or other error */ ret = record_stream_get_next(p_rs, &p_record, &recordlen); /* 循环从数据流中读取socket数据 */ if (ret == 0 && p_record == NULL) { /* end-of-stream */ break; } else if (ret < 0) { break; } else if (ret == 0) { /* && p_record != NULL */ processCommandBuffer(p_record, recordlen); /* 对接受到的数据进行组包，下发给vender ril，即libreference-ril.so */ } } }
processCommandBuffer(p_record, recordlen)对接收到的数据进行组包，下发给vender ril，即libreference-ril.so，
然后就脱离了RILD的控制了，libreference-ril.so主要是厂商对RILD控制modem接口的实现。
hardware/ril/libril/ril.cpp
static int processCommandBuffer(void *buffer, size_t buflen) { ... ... p.setData((uint8_t *) buffer, buflen); /* 把接受到的数据填装到parcel */ // status checked at end status = p.readInt32(&request); /* 解析request */ status = p.readInt32 (&token); /* 解析token，RILJ中的serial */ ... ... pRI = (RequestInfo *)calloc(1, sizeof(RequestInfo)); /* 分配一个RequestInfo，用于发送请求给vendor ril */ pRI->token = token; /* 设置token */ pRI->pCI = &(s_commands[request]); /* 设置请求 */ ret = pthread_mutex_lock(&s_pendingRequestsMutex); assert (ret == 0); pRI->p_next = s_pendingRequests; /* 添加到s_pendingRequests请求链表中 */ s_pendingRequests = pRI; ret = pthread_mutex_unlock(&s_pendingRequestsMutex); assert (ret == 0); /* sLastDispatchedToken = token; */ pRI->pCI->dispatchFunction(p, pRI); /* 执行事件回调，到这里开始进入vender ril了 */ return 0; }
我们仍然以获取SIM卡状态为例，pRI->pCI->dispatchFunction(p, pRI)对应调用了dispatchVoid()
hardware/ril/libril/ril.cpp
static void dispatchVoid (Parcel& p, RequestInfo *pRI) { clearPrintBuf; printRequest(pRI->token, pRI->pCI->requestNumber); s_callbacks.onRequest(pRI->pCI->requestNumber, NULL, 0, pRI); }
s_callbacks.onRequest(pRI->pCI->requestNumber, NULL, 0, pRI); 调用的就是libreference-ril.c中的onRequest()函数。
以上分析了RILD对RILJ下发的请求处理流程，下面接着分析RILD返回response给RILJ的流程。分两种情况，一种对请求的响应，
另一种是主动上报。
libreference-ril对请求处理完毕后，调用RIL_onRequestComplete回复RILJ该请求的处理结果。
hardware/ril/libril/ril.cpp
RIL_onRequestComplete(RIL_Token t, RIL_Errno e, void *response, size_t responselen) { ... ... p.writeInt32 (RESPONSE_SOLICITED); p.writeInt32 (pRI->token); errorOffset = p.dataPosition(); p.writeInt32 (e); if (response != NULL) { // there is a response payload, no matter success or not. ret = pRI->pCI->responseFunction(p, response, responselen); ... ... } ... ... sendResponse(p); ... ... } static int sendResponse (Parcel &p) { printResponse; return sendResponseRaw(p.data(), p.dataSize()); } static int sendResponseRaw (const void *data, size_t dataSize) { ... ... ret = blockingWrite(fd, (void *)&header, sizeof(header)); /* 先写4字节数据长度 */ if (ret < 0) { pthread_mutex_unlock(&s_writeMutex); return ret; } ret = blockingWrite(fd, data, dataSize); /* 再写数据 */ ... ... }
最终是通过sendResponseRaw()直接通过写socket回复RILJ。对于主动上报的处理是类似的，也是通过sendResponseRaw()
上报给RILJ。可以参考RIL_onUnsolicitedResponse()函数。
到此，RILJ与RILD之间的通信流程已经分析完，后续分析libreference-ril。libreference-ril中先关接口的实现方式，每个modem厂商都不一样。
BC72是通过串口/USB发送AT的方式控制，实现通话、短信、上网等功能。
谢谢！
