第二篇 4G模块-USB串口驱动测试

一、编译内核

         在linux内核里边修改了对华为ME909S-821的支持，使用make uImage编译，然后下载到开发板上：上电开机，在系统启动过程会打印相关usb串口驱动的信息，但是，我们也可以使用dmesg随时查看，相关信息如下：

usb 1-1: new full-speed USB device number 2 using s3c2410-ohci
cdc_ether 1-1:2.0: usb0: register 'cdc_ether' at usb-s3c24xx-1, CDC Ethernet Device, 02:1e:10:1f:00:00
option 1-1:2.2: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB0
option 1-1:2.3: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB1
option 1-1:2.4: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB2
option 1-1:2.5: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB3
option 1-1:2.6: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB4
option: option_instat_callback: error -2

最后出现错误： option_instat_callback error -2，尽管这个错误，目前还无法判断具体原因，开始测试在嵌入式开发板上打电话的功能（也就这个功能尤为吸引我）。

在这里我们要使用一个软件在ubuntu上，查看这个4G模块的信息，比如配置描述符、接口描述符、还有端点描述符等等，拥有这种功能的USB软件肯定有，幸运的是在内核大牛的网站看到这个 usbview软件，下载网址： 点击打开链接（ 感谢Greg K-H大牛）

 下载代码，解压，可参考 INSTALL文件编译安装usbview软件。

最后查看这个4G模块的信息如下：

Config Number: 1
	Number of Interfaces: 6
	Attributes: a0
	MaxPower Needed:   2mA

	Interface Number: 0
		Name: 
		Alternate Number: 0
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 10
		Number of Endpoints: 3

			Endpoint Address: 82
			Direction: in
			Attribute: 3
			Type: Int.
			Max Packet Size: 10
			Interval: 32ms

			Endpoint Address: 81
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 01
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

	Interface Number: 1
		Name: 
		Alternate Number: 0
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 13
		Number of Endpoints: 2

			Endpoint Address: 83
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 02
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

	Interface Number: 2
		Name: 
		Alternate Number: 0
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 12
		Number of Endpoints: 2

			Endpoint Address: 84
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 03
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

	Interface Number: 3
		Name: 
		Alternate Number: 0
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 16
		Number of Endpoints: 1

			Endpoint Address: 86
			Direction: in
			Attribute: 3
			Type: Int.
			Max Packet Size: 16
			Interval: 2ms

	Interface Number: 3
		Name: 
		Alternate Number: 1
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 16
		Number of Endpoints: 3

			Endpoint Address: 86
			Direction: in
			Attribute: 3
			Type: Int.
			Max Packet Size: 16
			Interval: 2ms

			Endpoint Address: 85
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 04
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

	Interface Number: 4
		Name: 
		Alternate Number: 0
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 06
		Number of Endpoints: 2

			Endpoint Address: 87
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 05
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

	Interface Number: 5
		Name: 
		Alternate Number: 0
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 1b
		Number of Endpoints: 2

			Endpoint Address: 88
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 06
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

Config Number: 2  //实际使用的配置
	Number of Interfaces: 7
	Attributes: a0
	MaxPower Needed:   2mA

	Interface Number: 0
		Name:cdc_ether
		Alternate Number: 0
		Class: 02(comm.) 
		Sub Class: 06
		Protocol: 00
		Number of Endpoints: 1

			Endpoint Address: 82
			Direction: in
			Attribute: 3
			Type: Int.
			Max Packet Size: 16
			Interval: 2ms

	Interface Number: 1 		

		Name: cdc_ether

		Alternate Number: 0
		Class: 0a(data ) 
		Sub Class: 06
		Protocol: 00
		Number of Endpoints: 2

			Endpoint Address: 81
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 01
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

	Interface Number: 2
		Name: option
		Alternate Number: 0
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 10
		Number of Endpoints: 3

			Endpoint Address: 84
			Direction: in
			Attribute: 3
			Type: Int.
			Max Packet Size: 10
			Interval: 32ms

			Endpoint Address: 83
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 02
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

	Interface Number: 3
		Name: option
		Alternate Number: 0
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 13
		Number of Endpoints: 2

			Endpoint Address: 85
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 03
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

	Interface Number: 4
		Name: option
		Alternate Number: 0
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 12
		Number of Endpoints: 2

			Endpoint Address: 86
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 04
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

	Interface Number: 5
		Name: option
		Alternate Number: 0
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 06
		Number of Endpoints: 2

			Endpoint Address: 87
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 05
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

	Interface Number: 6
		Name: option
		Alternate Number: 0
		Class: ff(vend.) 
		Sub Class: 06
		Protocol: 1b
		Number of Endpoints: 2

			Endpoint Address: 88
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 06
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

Config Number: 3
	Number of Interfaces: 2
	Attributes: a0
	MaxPower Needed:   2mA

	Interface Number: 0
		Name: 
		Alternate Number: 0
		Class: 02(comm.) 
		Sub Class: 0e
		Protocol: 00
		Number of Endpoints: 1

			Endpoint Address: 82
			Direction: in
			Attribute: 3
			Type: Int.
			Max Packet Size: 16
			Interval: 2ms

	Interface Number: 1
		Name: 
		Alternate Number: 0
		Class: 0a(data ) 
		Sub Class: 00
		Protocol: 02
		Number of Endpoints: 0

	Interface Number: 1
		Name: 
		Alternate Number: 1
		Class: 0a(data ) 
		Sub Class: 00
		Protocol: 02
		Number of Endpoints: 2

			Endpoint Address: 81
			Direction: in
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

			Endpoint Address: 01
			Direction: out
			Attribute: 2
			Type: Bulk
			Max Packet Size: 512
			Interval: 0ms

以上就是使用usbview软件查看的USB设备信息，这里对应这个ttyUSB0-ttyUSB4理解：

cdc_ether 1-1:2.0: usb0: register 'cdc_ether' at usb-s3c24xx-1, CDC Ethernet Device, 02:1e:10:1f:00:00
option 1-1:2.2: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB0
option 1-1:2.3: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB1
option 1-1:2.4: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB2
option 1-1:2.5: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB3
option 1-1:2.6: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB4

目前还没有拿到证据，但在观看这里的1-1.2.0到最后的1-1.2.6，估计2代表使用的配置2，就是上面的Config Number为2的配置描述符，后边的数字从0、2、3、4、5、6代表了上边的接口描述符，可以从接口描述符名字观察到，其中配置描述符2的接口描述符1没有使用上。

二、关于option_instat_callback error -2的原因

   【1】函数内容：

static void option_instat_callback(struct urb *urb)
{
	int err;
	int status = urb->status;
	struct usb_serial_port *port =  urb->context;
	struct option_port_private *portdata = usb_get_serial_port_data(port);

	dbg("%s", __func__);
	dbg("%s: urb %p port %p has data %p", __func__, urb, port, portdata);

	if (status == 0) {
		struct usb_ctrlrequest *req_pkt =
				(struct usb_ctrlrequest *)urb->transfer_buffer;

		if (!req_pkt) {
			dbg("%s: NULL req_pkt", __func__);
			return;
		}
		if ((req_pkt->bRequestType == 0xA1) &&
				(req_pkt->bRequest == 0x20)) {
			int old_dcd_state;
			unsigned char signals = *((unsigned char *)
					urb->transfer_buffer +
					sizeof(struct usb_ctrlrequest));

			dbg("%s: signal x%x", __func__, signals);

			old_dcd_state = portdata->dcd_state;
			portdata->cts_state = 1;
			portdata->dcd_state = ((signals & 0x01) ? 1 : 0);
			portdata->dsr_state = ((signals & 0x02) ? 1 : 0);
			portdata->ri_state = ((signals & 0x08) ? 1 : 0);

			if (old_dcd_state && !portdata->dcd_state) {
				struct tty_struct *tty =
						tty_port_tty_get(&port->port);
				if (tty && !C_CLOCAL(tty))
					tty_hangup(tty);
				tty_kref_put(tty);
			}
		} else {
			dbg("%s: type %x req %x", __func__,
				req_pkt->bRequestType, req_pkt->bRequest);
		}
++++++	}else if(status ==-ENOENT || status == -ESHUTDOWN) {
++++++         dbg("%s: urb stopped: %d\n", __func__, status); 
        }else
               err("%s: error %d", __func__, status);

	/* Resubmit urb so we continue receiving IRQ data */
	if (status != -ESHUTDOWN && status != -ENOENT) {
		err = usb_submit_urb(urb, GFP_ATOMIC);
		if (err)
			dbg("%s: resubmit intr urb failed. (%d)",
				__func__, err);
	}
}

找了好久，在linux-usb的邮件里边找到了一个人提交的patch，里边描述的问题正好就是option: option_instat_callback: error -2，综合了他的修改，同时在option.c文件前边加上dbg函数：

#ifdef CONFIG_USB_DEBUG
static int mydebug = 5;
#else
static int mydebug = 1;
#endif

/* Use our own dbg macro */
#undef dbg
#define dbg(format, arg...) 					\
do { 									\ 
	if(mydebug > 3)							\
		printk(KERN_DEBUG "%s: " format "\n", __FILE__, ##arg);	\
} while (0)