Asterisk Dial到 dahdi 驱动调用过程

Dail 是Asterisk 的一个application, 源代码在 asteriskappsapp_dial.c
跟踪其关键代码如下：

static int load_module(void)
{
int res;
res = ast_register_application_xml(app, dial_exec);
res |= ast_register_application_xml(rapp, retrydial_exec);
return res;
}
dial_exec
dial_exec_full
ast_request
ast_call
chan->tech->call
// 如: Dail(sip/6001) 将会调用 chan_sip 的call 函数

本文跟踪 Dial（dahdi/1/s）的调用过程，实际上最终调用了 chan_dahdi 的call 函数。

static struct ast_channel_tech dahdi_tech = {
.type = "DAHDI",
...
.call = dahdi_call,
...
};

dahdi_call
analog_call(p->sig_pvt, ast, rdest, timeout);
analog_ring(p);
my_ring(p);
dahdi_ring_phone(p);
x = DAHDI_ONHOOK;
res = ioctl(p->subs[SUB_REAL].dfd, DAHDI_HOOK, &x);
do {
x = DAHDI_RING;
res = ioctl(p->subs[SUB_REAL].dfd, DAHDI_HOOK, &x);
}

dahdi_call 最终调用 dahdi_ring_phone 函数，里面
首先 用 ioctl DAHDI_HOOK DAHDI_ONHOOK 确保是挂机状态
再 ioctl DAHDI_HOOK DAHDI_RING 发起振铃

dahdi 驱动层对应代码：
dahdi-base.c
dahdi_chan_ioctl 中

switch (j) {
case DAHDI_ONHOOK:
spin_lock_irqsave(&chan->lock, flags);
dahdi_hangup(chan);
//挂机
spin_unlock_irqrestore(&chan->lock, flags);
break;
case DAHDI_OFFHOOK:
spin_lock_irqsave(&chan->lock, flags);
if ((chan->txstate == DAHDI_TXSTATE_KEWL) ||
(chan->txstate == DAHDI_TXSTATE_AFTERKEWL)) {
spin_unlock_irqrestore(&chan->lock, flags);
return -EBUSY;
}
dahdi_rbs_sethook(chan, DAHDI_TXSIG_OFFHOOK, DAHDI_TXSTATE_DEBOUNCE, chan->debouncetime);
spin_unlock_irqrestore(&chan->lock, flags);
break;
case DAHDI_RING:
case DAHDI_START:
spin_lock_irqsave(&chan->lock, flags);
if (!chan->curzone) {
spin_unlock_irqrestore(&chan->lock, flags);
module_printk(KERN_WARNING, "Cannot start tone until a tone zone is loaded.n");
return -ENODATA;
}
if (chan->txstate != DAHDI_TXSTATE_ONHOOK) {
spin_unlock_irqrestore(&chan->lock, flags);
return -EBUSY;
}
if (chan->sig & __DAHDI_SIG_FXO) {
ret = 0;
chan->cadencepos = 0;
ret = chan->ringcadence[0];
dahdi_rbs_sethook(chan, DAHDI_TXSIG_START, DAHDI_TXSTATE_RINGON, ret);
} else
dahdi_rbs_sethook(chan, DAHDI_TXSIG_START, DAHDI_TXSTATE_START, chan->starttime);
spin_unlock_irqrestore(&chan->lock, flags);
if (file->f_flags & O_NONBLOCK)
return -EINPROGRESS;
break;

其中 dahdi_hangup 里面也是调用 dahdi_rbs_sethook
dahdi_rbs_sethook 最终调用的是 wctdm_hooksig 。
wctdm_hooksig 中需要实现的是对 ONHOOK 、OFFHOOK、START(RING)的硬件层处理。

Q1.caller id 是怎么发送的？

跟踪 asterisk debug

[Jun 14 07:33:00] DEBUG[2741][C-00000001] rtp_engine.c: Can't find native functions for channel 'DAHDI/8-1'
[Jun 14 07:33:00] DEBUG[2741][C-00000001] sig_analog.c: CALLING CID_NAME: 8000 CID_NUM:: 8000
[Jun 14 07:33:00] DEBUG[2741][C-00000001] sig_analog.c: FXO: setup deferred dialstring: 12
[Jun 14 07:33:01] DEBUG[2741][C-00000001] channel.c: Channel DAHDI/8-1 setting read format path: ulaw -> ulaw
[Jun 14 07:33:01] DEBUG[2741][C-00000001] channel.c: Channel SIP/8000-00000000 setting write format path: ulaw -> ulaw
[Jun 14 07:33:01] DEBUG[2741][C-00000001] channel.c: Channel SIP/8000-00000000 setting read format path: ulaw -> ulaw
[Jun 14 07:33:01] DEBUG[2741][C-00000001] channel.c: Channel DAHDI/8-1 setting write format path: ulaw -> ulaw
[Jun 14 07:33:01] DEBUG[2724] devicestate.c: No provider found, checking channel drivers for DAHDI - 8
[Jun 14 07:33:01] DEBUG[2741][C-00000001] chan_sip.c: Trying to put 'SIP/2.0 180' onto UDP socket destined for 172.16.0.158:14894
[Jun 14 07:33:01] DEBUG[2724] devicestate.c: Changing state for DAHDI/8 - state 6 (Ringing)
[Jun 14 07:33:02] DEBUG[2741][C-00000001] sig_analog.c: analog_exception 8
[Jun 14 07:33:02] DEBUG[2741][C-00000001] sig_analog.c: Exception on 11, channel 8
[Jun 14 07:33:02] DEBUG[2741][C-00000001] sig_analog.c: __analog_handle_event 8
[Jun 14 07:33:02] DEBUG[2741][C-00000001] sig_analog.c: Got event ANALOG_EVENT_RINGEROFF(8) on channel 8 (index 0)
[Jun 14 07:33:02] DEBUG[2741][C-00000001] sig_analog.c: Sending callerid.
CID_NAME: '8000' CID_NUM: '8000'
[Jun 14 07:33:02] DEBUG[2741][C-00000001] chan_dahdi.c: Starting cid spill
[Jun 14 07:33:02] DEBUG[2741][C-00000001] chan_dahdi.c: writing callerid at pos 0 of 9267, res = 160
][Jun 14 07:33:02] DEBUG[2741][C-00000001] chan_dahdi.c: writing callerid at pos 160 of 9267, res = 160
[Jun 14 07:33:02] DEBUG[2741][C-00000001] chan_dahdi.c: writing callerid at pos 320 of 9267, res = 160
[Jun 14 07:33:02] DEBUG[2741][C-00000001] chan_dahdi.c: writing callerid at pos 480 of 9267, res = 160
[Jun 14 07:33:02] DEBUG[2741][C-00000001] chan_dahdi.c: writing callerid at pos 640 of 9267, res = -1

结合代码可知：
asterisk 检测到ANALOG_EVENT_RINGEROFF 的event 时，调用 analog_send_callerid 。

__analog_handle_event
//asterisk-16.0.0channelssig_analog.c
case ANALOG_EVENT_RINGEROFF:
analog_send_callerid(p, 0, &p->caller)
analog_callbacks.send_callerid ()
my_send_callerid
send_callerid
write(p->subs[SUB_REAL].dfd,...)

最终是调用write 将数据写入驱动，已经知道write 写入的数据，在驱动中最终是通过pcm 发送出去。
由此推测callerrid 最终是转化成了声音数据，传输给模块，这个声音猜测是DTMF声音，模块端解码DTMF数据可以得到callerid 。

最后

以上就是谨慎凉面为你收集整理的Asterisk Dial到 dahdi 驱动调用过程的全部内容，希望文章能够帮你解决Asterisk Dial到 dahdi 驱动调用过程所遇到的程序开发问题。

如果觉得靠谱客网站的内容还不错，欢迎将靠谱客网站推荐给程序员好友。