Android4.0 USB挂载内核驱动层流程分析（一）

1.platform_device
在arch/arm/mach-msm/Board-xx.c中：

static struct platform_device android_usb_device = {.name = "android_usb",.id = -1,.dev = {.platform_data = &android_usb_pdata,  //@1}};static struct android_usb_platform_data android_usb_pdata = {.update_pid_and_serial_num = usb_diag_update_pid_and_serial_num,};

在rpc_hsusb.c中：

int usb_diag_update_pid_and_serial_num(uint32_t pid, const char *snum){int ret;ret = msm_hsusb_send_productID(pid);if (ret)return ret;if (!snum) {ret = msm_hsusb_is_serial_num_null(1);if (ret)return ret;return 0;}ret = msm_hsusb_is_serial_num_null(0);if (ret)return ret;ret = msm_hsusb_send_serial_number(snum);if (ret)return ret;return 0;}

在内核初始化时，先注册了名为android_usb的设备。

2.platform_driver

在drivers/usb/gadget/Android.c中：

static struct platform_driver android_platform_driver = {.driver = { .name = "android_usb"},};

注册了名为android_usb的paltform_driver。但是并不像其他硬件驱动那样，有.probe函数用来匹配驱动。不要着急，慢慢看。

3.module_init

其实Android.c用的是module_init的方式：

static int __init init(void){struct android_dev *dev;int err;android_class = class_create(THIS_MODULE, "android_usb");    //在sys/class下创建android_usb目录if (IS_ERR(android_class))    //错误处理return PTR_ERR(android_class);dev = kzalloc(sizeof(*dev), GFP_KERNEL);if (!dev)return -ENOMEM;dev->functions = supported_functions;    //设备支持的一些功能，功能列表/**static struct android_usb_function *supported_functions[] = {* &rmnet_smd_function,* &rmnet_sdio_function,* &rmnet_smd_sdio_function,* &rmnet_function,* &diag_function,* &serial_function,* &adb_function,* &ccid_function,*// &acm_function,* &mtp_function,* &ptp_function,* &rndis_function,* &mass_storage_function,* &accessory_function,* NULL*};*/INIT_LIST_HEAD(&dev->enabled_functions);    //应该是加入到队列里的意思吧，使能这些功能INIT_WORK(&dev->work, android_work);err = android_create_device(dev);    //创建dev，按内核目录来看：/**localhost android_usb # ls                                                     *android0          f_diag            f_rmnet           f_rndis*f_accessory       f_mass_storage    f_rmnet_sdio      f_serial*f_adb             f_mtp             f_rmnet_smd*f_ccid            f_ptp             f_rmnet_smd_sdio*localhost android_usb # */if (err) {class_destroy(android_class);kfree(dev);return err;}_android_dev = dev;/* Override composite driver functions */composite_driver.setup = android_setup;composite_driver.disconnect = android_disconnect;platform_driver_probe(&android_platform_driver, android_probe);    //驱动是通过platform_driver_probe方式进行匹配的，匹配函数位android_probe:/**static int __devinit android_probe(struct platform_device *pdev)*{* struct android_usb_platform_data *pdata = pdev->dev.platform_data;    //见@1* struct android_dev *dev = _android_dev;** dev->pdata = pdata;* * return 0;*}*/return usb_composite_probe(&android_usb_driver, android_bind);    //万能USB驱动，用android_bind进行绑定}module_init(init);static void __exit cleanup(void){usb_composite_unregister(&android_usb_driver);class_destroy(android_class);kfree(_android_dev);_android_dev = NULL;}module_exit(cleanup);

我认为是有两个重点，一个是supported_functions，另一个是android_bind。下一篇博客继续分析。