S5P4418：4G 模块 EC20 移植和测试笔记
1. 前言
限于作者能力水平，本文可能存在的谬误，因此而给读者带来的损失，作者不做任何承诺。
2. 适配和测试
2.1 适配
修改文件drivers/usb/serial/option.c，增加设备的 VID & PID：
static const struct usb_device_id option_ids[] = {
{ USB_DEVICE(0x05C6, 0x9215) }, // 为 EC20 模块增加 VID & PID
{ USB_DEVICE(0x2C7C, 0x0125) }, // EC20CFD-512-STD.
...
};
2.2 测试
(1) 下电，如下图连接好 4G 模块, 4G 天线,插入 SIM 卡
(2) 上电。系统启动到出现命令提示符时,会得到如下输出:
(3) 运行 lsusb 命令查看 4G 模块的USB连接状况，EC20 4G 的模块会有如下图红框中的 USB 设备 ID(VID & PID):
每个厂商的 4G 模块的 USB 设备 VID & PID 是不同的，所以对不同的 4G 模块，上面的输出是不同的。
(4) 查看是否存在 /dev/ttyUSB* 虚拟串口设备节点，这些设备是 4G 模块用来通信的，每个设备节点用途不同。如果不存在这些设备，4G 模块是不能正常工作的。
(5) 4G 拨号连接。运行命令pppd call quectel-ppp & 进行拨号,正常情况会得到如下输出:
# pppd call quectel-ppp &
# pppd options in effect:
debug # (from /etc/ppp/peers/quectel-ppp)
nodetach # (from /etc/ppp/peers/quectel-ppp)
dump # (from /etc/ppp/peers/quectel-ppp)
noauth # (from /etc/ppp/peers/quectel-ppp)
user test # (from /etc/ppp/peers/quectel-ppp)
password ?????? # (from /etc/ppp/peers/quectel-ppp)
remotename 3gppp # (from /etc/ppp/peers/quectel-ppp)
/dev/ttyUSB3 # (from /etc/ppp/peers/quectel-ppp)
115200 # (from /etc/ppp/peers/quectel-ppp)
lock # (from /etc/ppp/peers/quectel-ppp)
connect chat -s -v -f /etc/ppp/peers/quectel-chat-connect # (from /etc/ppp/peers/quectel-ppp)
disconnect chat -s -v -f /etc/ppp/peers/quectel-chat-disconnect
# (from /etc/ppp/peers/quectel-ppp)
nocrtscts # (from /etc/ppp/peers/quectel-ppp)
modem # (from /etc/ppp/peers/quectel-ppp)
hide-password # (from /etc/ppp/peers/quectel-ppp)
novj # (from /etc/ppp/peers/quectel-ppp)
novjccomp # (from /etc/ppp/peers/quectel-ppp)
ipcp-accept-local # (from /etc/ppp/peers/quectel-ppp)
ipcp-accept-remote # (from /etc/ppp/peers/quectel-ppp)
ipparam 3gppp # (from /etc/ppp/peers/quectel-ppp)
noipdefault # (from /etc/ppp/peers/quectel-ppp)
ipcp-max-failure 30 # (from /etc/ppp/peers/quectel-
ppp)
defaultroute # (from /etc/ppp/peers/quectel-ppp)
usepeerdns # (from /etc/ppp/peers/quectel-ppp)
noccp # (from /etc/ppp/peers/quectel-ppp)
abort on (BUSY)
abort on (NO CARRIER)
abort on (NO DIALTONE)
abort on (ERROR)
abort on (NO ANSWER)
timeout set to 30 seconds
send (AT^M)
expect (OK)
AT^M^M
OK
-- got it
send (ATE0^M)
expect (OK)
^M
ATE0^M^M
OK
-- got it
send (ATI;+CSUB;+CSQ;+CPIN?;+COPS?;+CGREG?;&D2^M)
expect (OK)
^M
^M
Quectel^M
EC20^M
Revision: EC20CQAR02A07E2G^M
^M
SubEdition: V03^M
^M
+CSQ: 28,99^M
^M
+CPIN: READY^M
^M
+COPS: 0,0,"CHINA MOBILE CMCC",7^M
^M
expect (CONNECT)
^M
^M
CONNECT
-- got it
Script chat -s -v -f /etc/ppp/peers/quectel-chat-connect finished (pid 228), status = 0x0
Serial connection established.
using channel 1
Using interface ppp0
Connect: ppp0 <--> /dev/ttyUSB3
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0xc97b788e>
<pcomp> <accomp>]
rcvd [LCP ConfReq id=0x0 <asyncmap 0x0> <auth chap MD5> <magic 0x16be8765> <pcomp> <accomp>]
sent [LCP ConfAck id=0x0 <asyncmap 0x0> <auth chap MD5> <magic 0x16be8765> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0xc97b788e> <pcomp> <accomp>]
rcvd [LCP DiscReq id=0x1 magic=0x16be8765]
rcvd [CHAP Challenge id=0x1 <ce75169e767890d400f8d45890f5e505>, name = "UMTS_CHAP_SRVR"]
sent [CHAP Response id=0x1 <16e21983dd474e25f437c19846143f1d>, name = "test"]
rcvd [CHAP Success id=0x1 ""]
CHAP authentication succeeded
CHAP authentication succeeded
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
rcvd [IPCP ConfReq id=0x0]
sent [IPCP ConfNak id=0x0 <addr 0.0.0.0>]
rcvd [IPCP ConfNak id=0x1 <addr 10.20.52.69> <ms-dns1 221.179.38.7> <ms-dns2 120.196.165.7>]
sent [IPCP ConfReq id=0x2 <addr 10.20.52.69> <ms-dns1 221.179.38.7> <ms-dns2 120.196.165.7>]
rcvd [IPCP ConfReq id=0x1]
sent [IPCP ConfAck id=0x1]
rcvd [IPCP ConfAck id=0x2 <addr 10.20.52.69> <ms-dns1 221.179.38.7> <ms-dns2 120.196.165.7>]
Could not determine remote IP address: defaulting to 10.64.64.64
local IP address 10.20.52.69
remote IP address 10.64.64.64
primary DNS address 221.179.38.7
secondary DNS address 120.196.165.7
最后 4 行输出，表示已经成功获取到 IP，并分配了 DNS 服务器。
(6) 运行 ifconfig 命令查看是否存在拨号设备
上图中 ppp0 就是新的拨号设备。
(7) 用 4G 模块上网。测试中，我们拔掉所有网线，确保是从 4G 模块进行的网络通信。
由上图可见,已经可以上网了。
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