USB驱动之三host模式下usb设备匹配驱动过程以数据流向图

我们知道usb的设备和驱动是根据id进行匹配，具体的匹配过程如下

在kernel4.4/drivers/usb/storage/usb.c的storage_probe函数中加上WARN_ON(1)把相应的堆栈打印出来，如下

[   74.336697] sprd-typec 41800000.spi:pmic@0:typec@380: now works as drp and is in Attached.SRC state,event 1,status 5 cc_status e002
[   74.369709] musb-sprd 20200000.usb: sprd_musb_enable:HOST ENABLE 81
[   74.369752] musb-sprd 20200000.usb: enter into resume mode
[   74.370473] musb-sprd 20200000.usb: is running as HOST
[   74.543117] musb_interrupt
[   74.543151] musb-hdrc musb-hdrc.0.auto: ** IRQ host usb0010 tx0000 rx0000
[   74.543165] musb-hdrc musb-hdrc.0.auto: <== DevCtl=5d, int_usb=0x10
[   74.543198] musb-hdrc musb-hdrc.0.auto: CONNECT (a_host) devctl 5d
[   74.543274] usb usb1: usb wakeup-resume
[   74.543308] hub 1-0:1.0: hub_resume
[   74.543512] usb usb1-port1: status 0101 change 0001
[   74.580904] n=0,value=0x0,addr_ic=0x2a4,val=0x0
[   74.643842] kick_hub_wq
[   74.643895] queue_work hub_event
[   74.643944] hub_event
[   74.643968] hub 1-0:1.0: state 8 ports 1 chg 0002 evt 0000
[   74.643993] port_event
[   74.644210] usb usb1-port1: status 0101, change 0000, 12 Mb/s
[   74.644230] hub_port_connect
[   74.644301] hub_port_init
[   74.756284] usb 1-1: new high-speed USB device number 2 using musb-hdrc
[   74.884839] usb 1-1: udev 2, busnum 1, minor = 1
[   74.884862] usb 1-1: New USB device found, idVendor=1908, idProduct=0226
[   74.884883] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[   74.888995] generic_probe
[   74.891031] ------------[ cut here ]------------
[   74.891057] WARNING: at /kernel4.4/drivers/usb/storage/usb.c:1089
[   74.891164] CPU: 0 PID: 723 Comm: kworker/0:2 Tainted: G        W  O    4.4.147 #34
[   74.891177] Hardware name: Spreadtrum SC9863A Board (DT)
[   74.891202] Workqueue: usb_hub_wq hub_event
[   74.891221] task: ffffffc06eac2080 task.stack: ffffffc0733ec000
[   74.891241] PC is at storage_probe+0x2c/0x110
[   74.891258] LR is at usb_probe_interface+0x1b8/0x30c
[   74.904736] [<ffffff80086b05c8>] storage_probe+0x2c/0x110
[   74.904756] [<ffffff800867e194>] usb_probe_interface+0x1b8/0x30c
[   74.904780] [<ffffff800853858c>] driver_probe_device+0x204/0x45c
[   74.904799] [<ffffff8008538928>] __device_attach_driver+0x94/0xd8
[   74.904821] [<ffffff8008535db0>] bus_for_each_drv+0x74/0xc4
[   74.904840] [<ffffff80085381c8>] __device_attach+0xd8/0x154
[   74.904855] [<ffffff8008538b14>] device_initial_probe+0x24/0x30
[   74.904875] [<ffffff800853758c>] bus_probe_device+0x9c/0xa4
[   74.904895] [<ffffff8008534864>] device_add+0x42c/0x5a4
[   74.904916] [<ffffff800867c24c>] usb_set_configuration+0x4a4/0x834
[   74.904932] [<ffffff800868ace4>] generic_probe+0x48/0xac
[   74.904952] [<ffffff800867db24>] usb_probe_device+0x48/0xa4
[   74.904968] [<ffffff800853858c>] driver_probe_device+0x204/0x45c
[   74.904983] [<ffffff8008538928>] __device_attach_driver+0x94/0xd8
[   74.905000] [<ffffff8008535db0>] bus_for_each_drv+0x74/0xc4
[   74.905015] [<ffffff80085381c8>] __device_attach+0xd8/0x154
[   74.905030] [<ffffff8008538b14>] device_initial_probe+0x24/0x30
[   74.905046] [<ffffff800853758c>] bus_probe_device+0x9c/0xa4
[   74.905062] [<ffffff8008534864>] device_add+0x42c/0x5a4
[   74.905082] [<ffffff8008671d40>] usb_new_device+0x248/0x47c
[   74.905102] [<ffffff80086735d4>] hub_event+0x978/0x1154
[   74.905125] [<ffffff80080c9024>] process_one_work+0x154/0x444
[   74.905145] [<ffffff80080c9440>] worker_thread+0x12c/0x448
[   74.905167] [<ffffff80080d0358>] kthread+0xe8/0xfc
[   74.905188] [<ffffff8008085ab0>] ret_from_fork+0x10/0x20
[   74.905427] usb-storage 1-1:1.0: USB Mass Storage device detected
[   74.910746] scsi host0: usb-storage 1-1:1.0
[   74.921651] hub_event
[   74.921679] hub 1-0:1.0: state 8 ports 1 chg 0000 evt 0002
[   74.921700] port_event
[   74.921851] usb usb1-port1: enable change, status 00000503

usb设备和驱动的匹配过程稍有点复杂，关键代码如下

drivers/usb/core.c 

static int __init usb_init(void)
{
	bus_register(&usb_bus_type);
	usb_register_device_driver(&usb_generic_driver, THIS_MODULE);
}

struct bus_type usb_bus_type = {
	.name =		"usb",
	.match =	usb_device_match,
	.uevent =	usb_uevent,
};

static inline int is_usb_device(const struct device *dev)
{
	return dev->type == &usb_device_type;
}

static inline int is_usb_interface(const struct device *dev)
{
	return dev->type == &usb_if_device_type;
}

static inline int is_usb_device_driver(struct device_driver *drv)
{
	return container_of(drv, struct usbdrv_wrap, driver)->
			for_devices;
}

static int usb_device_match(struct device *dev, struct device_driver *drv)
{
	/* devices and interfaces are handled separately */
	if (is_usb_device(dev)) {

		/* interface drivers never match devices */
		if (!is_usb_device_driver(drv))
			return 0;

		/* TODO: Add real matching code */
		return 1;

	} else if (is_usb_interface(dev)) {
		struct usb_interface *intf;
		struct usb_driver *usb_drv;
		const struct usb_device_id *id;

		/* device drivers never match interfaces */
		if (is_usb_device_driver(drv))
			return 0;

		intf = to_usb_interface(dev);
		usb_drv = to_usb_driver(drv);

		id = usb_match_id(intf, usb_drv->id_table);
		if (id)
			return 1;

		id = usb_match_dynamic_id(intf, usb_drv);
		if (id)
			return 1;
	}

	return 0;
}

 相应的数据流向如下