hub_thread
1. 流程图
2. usb_hub_init()
int usb_hub_init(void)
{
//1. 注册usb hub驱动
if (usb_register(&hub_driver) < 0) { //注册hub驱动到usb子系统总线上
printk(KERN_ERR "%s: can't register hub driver\n",
usbcore_name);
return -1;
}
//2. hub_thread内部是完成设备的枚举，即创建usb设备，最终调用1.中的驱动match完成相应的驱动注册
khubd_task = kthread_run(hub_thread, NULL, "khubd"); //创建hub内核线程
if (!IS_ERR(khubd_task))
return 0;
/* Fall through if kernel_thread failed */
usb_deregister(&hub_driver);
printk(KERN_ERR "%s: can't start khubd\n", usbcore_name);
return -1;
}前面已经分析过了hub驱动的注册流程，详见:点击打开链接，这里主要分析hub_thread线程内部的工作原理。
3. hub_thread()
khubd_task = kthread_run(hub_thread, NULL, "khubd"); //创建hub内核线程static int hub_thread(void *__unused)
{
/* khubd needs to be freezable to avoid intefering with USB-PERSIST
* port handover. Otherwise it might see that a full-speed device
* was gone before the EHCI controller had handed its port over to
* the companion full-speed controller.
*/
set_freezable();
do {
hub_events();
wait_event_freezable(khubd_wait,
!list_empty(&hub_event_list) ||
kthread_should_stop());
} while (!kthread_should_stop() || !list_empty(&hub_event_list));
pr_debug("%s: khubd exiting\n", usbcore_name);
return 0;
}hub_thread()函数内部的主要工作是等待khubd_wait事件的发生，前提是该事件的条件hub_event_list不为NULL，在ehci主机控制器这一节(详见:点击打开链接, “第5.4 usb_hcd_request_irqs()”)我们分析过是如何唤醒该khubd_wait，等待事件的，这里不再赘述！所以当主机控制器ehci上有设备接入时(如U盘)，ehci将唤醒khubd_wait，这里wait_event_freezable()等待事件成立将调用hub_event()事件函数。
4. hub_event()
static void hub_events(void)
{
struct list_head *tmp;
struct usb_device *hdev;
struct usb_interface *intf;
struct usb_hub *hub;
struct device *hub_dev;
u16 hubstatus;
u16 hubchange;
u16 portstatus;
u16 portchange;
int i, ret;
int connect_change, wakeup_change;
/*
* We restart the list every time to avoid a deadlock with
* deleting hubs downstream from this one. This should be
* safe since we delete the hub from the event list.
* Not the most efficient, but avoids deadlocks.
*/
while (1) {
/* Grab the first entry at the beginning of the list */
spin_lock_irq(&hub_event_lock);
if (list_empty(&hub_event_list)) {
spin_unlock_irq(&hub_event_lock);
break;
}
tmp = hub_event_list.next; //获取hub_event_list.next的指针，即当前hub
list_del_init(tmp); //将当前hub从hub_event_list链表中删除
hub = list_entry(tmp, struct usb_hub, event_list); //这里需要看下是如何将hub设备添加到链表中的？？？
kref_get(&hub->kref);
spin_unlock_irq(&hub_event_lock);
hdev = hub->hdev; //从usb-hub中获取usb设备
hub_dev = hub->intfdev;
intf = to_usb_interface(hub_dev); //获取接口
dev_dbg(hub_dev, "state %d ports %d chg %04x evt %04x\n",
hdev->state, hub->descriptor
? hub->descriptor->bNbrPorts
: 0,
/* NOTE: expects max 15 ports... */
(u16) hub->change_bits[0],
(u16) hub->event_bits[0]);
/* Lock the device, then check to see if we were
* disconnected while waiting for the lock to succeed. */
usb_lock_device(hdev);
if (unlikely(hub->disconnected))
goto loop_disconnected;
/* If the hub has died, clean up after it */
if (hdev->state == USB_STATE_NOTATTACHED) { /*判定当前的hub是否没有被附上（断开）*/
hub->error = -ENODEV;
hub_quiesce(hub, HUB_DISCONNECT);
goto loop;
}
/* Autoresume */
ret = usb_autopm_get_interface(intf);
if (ret) {
dev_dbg(hub_dev, "Can't autoresume: %d\n", ret);
goto loop;
}
/* If this is an inactive hub, do nothing */
if (hub->quiescing) //quiescing：静默
goto loop_autopm;
if (hub->error) {
dev_dbg (hub_dev, "resetting for error %d\n",
hub->error);
ret = usb_reset_device(hdev);
if (ret) {
dev_dbg (hub_dev,
"error resetting hub: %d\n", ret);
goto loop_autopm;
}
hub->nerrors = 0;
hub->error = 0;
}
/* deal with port status changes */
for (i = 1; i <= hub->descriptor->bNbrPorts; i++) { //遍历端口
if (test_bit(i, hub->busy_bits))
continue;
connect_change = test_bit(i, hub->change_bits);
wakeup_change = test_and_clear_bit(i, hub->wakeup_bits);
if (!test_and_clear_bit(i, hub->event_bits) &&
!connect_change && !wakeup_change)
continue;
ret = hub_port_status(hub, i,
&portstatus, &portchange);
if (ret < 0)
continue;
if (portchange & USB_PORT_STAT_C_CONNECTION) { //端口状态连接？
usb_clear_port_feature(hdev, i,
USB_PORT_FEAT_C_CONNECTION);
connect_change = 1;
}
if (portchange & USB_PORT_STAT_C_ENABLE) { //端口状态使能？
if (!connect_change)
dev_dbg (hub_dev,
"port %d enable change, "
"status %08x\n",
i, portstatus);
usb_clear_port_feature(hdev, i,
USB_PORT_FEAT_C_ENABLE);
/*
* EM interference sometimes causes badly
* shielded USB devices to be shutdown by
* the hub, this hack enables them again.
* Works at least with mouse driver.
*/
if (!(portstatus & USB_PORT_STAT_ENABLE)
&& !connect_change
&& hub->ports[i - 1]->child) {
dev_err (hub_dev,
"port %i "
"disabled by hub (EMI?), "
"re-enabling...\n",
i);
connect_change = 1;
}
}
//确定是否远程唤醒，如usb模块进入了休眠
if (hub_handle_remote_wakeup(hub, i,
portstatus, portchange))
connect_change = 1;
if (portchange & USB_PORT_STAT_C_OVERCURRENT) { //端口状态过流？
u16 status = 0;
u16 unused;
dev_dbg(hub_dev, "over-current change on port "
"%d\n", i);
usb_clear_port_feature(hdev, i,
USB_PORT_FEAT_C_OVER_CURRENT);
msleep(100); /* Cool down */
hub_power_on(hub, true);
hub_port_status(hub, i, &status, &unused);
if (status & USB_PORT_STAT_OVERCURRENT)
dev_err(hub_dev, "over-current "
"condition on port %d\n", i);
}
if (portchange & USB_PORT_STAT_C_RESET) { //端口状态复位？
dev_dbg (hub_dev,
"reset change on port %d\n",
i);
usb_clear_port_feature(hdev, i,
USB_PORT_FEAT_C_RESET);
}
if ((portchange & USB_PORT_STAT_C_BH_RESET) &&
hub_is_superspeed(hub->hdev)) {
dev_dbg(hub_dev,
"warm reset change on port %d\n",
i);
usb_clear_port_feature(hdev, i,
USB_PORT_FEAT_C_BH_PORT_RESET);
}
if (portchange & USB_PORT_STAT_C_LINK_STATE) {
usb_clear_port_feature(hub->hdev, i,
USB_PORT_FEAT_C_PORT_LINK_STATE);
}
if (portchange & USB_PORT_STAT_C_CONFIG_ERROR) {
dev_warn(hub_dev,
"config error on port %d\n",
i);
usb_clear_port_feature(hub->hdev, i,
USB_PORT_FEAT_C_PORT_CONFIG_ERROR);
}
/* Warm reset a USB3 protocol port if it's in
* SS.Inactive state.
*/
if (hub_port_warm_reset_required(hub, portstatus)) {
int status;
struct usb_device *udev =
hub->ports[i - 1]->child;
dev_dbg(hub_dev, "warm reset port %d\n", i);
if (!udev ||
!(portstatus & USB_PORT_STAT_CONNECTION) ||
udev->state == USB_STATE_NOTATTACHED) {
status = hub_port_reset(hub, i,
NULL, HUB_BH_RESET_TIME,
true);
if (status < 0)
hub_port_disable(hub, i, 1);
} else {
usb_lock_device(udev);
status = usb_reset_device(udev);
usb_unlock_device(udev);
connect_change = 0;
}
}
if (connect_change) //从上面遍历的端口中获取到usb口有改变，将调用如下接口！！！
hub_port_connect_change(hub, i,
portstatus, portchange);
} /* end for i */
/* deal with hub status changes */
if (test_and_clear_bit(0, hub->event_bits) == 0)
; /* do nothing */
else if (hub_hub_status(hub, &hubstatus, &hubchange) < 0)
dev_err (hub_dev, "get_hub_status failed\n");
else {
if (hubchange & HUB_CHANGE_LOCAL_POWER) {
dev_dbg (hub_dev, "power change\n");
clear_hub_feature(hdev, C_HUB_LOCAL_POWER);
if (hubstatus & HUB_STATUS_LOCAL_POWER)
/* FIXME: Is this always true? */
hub->limited_power = 1;
else
hub->limited_power = 0;
}
if (hubchange & HUB_CHANGE_OVERCURRENT) {
u16 status = 0;
u16 unused;
dev_dbg(hub_dev, "over-current change\n");
clear_hub_feature(hdev, C_HUB_OVER_CURRENT);
msleep(500); /* Cool down */
hub_power_on(hub, true);
hub_hub_status(hub, &status, &unused);
if (status & HUB_STATUS_OVERCURRENT)
dev_err(hub_dev, "over-current "
"condition\n");
}
}
loop_autopm:
/* Balance the usb_autopm_get_interface() above */
usb_autopm_put_interface_no_suspend(intf);
loop:
/* Balance the usb_autopm_get_interface_no_resume() in
* kick_khubd() and allow autosuspend.
*/
usb_autopm_put_interface(intf);
loop_disconnected:
usb_unlock_device(hdev);
kref_put(&hub->kref, hub_release);
} /* end while (1) */
}从hub_event_list链表中获取当前的hub，然后遍历该hub的端口，判断该端口对应的状态(状态包括：是否过流、端口是否使能、端口复位...)是否改变正确(正确connect_change=1，反之=0)，正确将调用hub_port_connect_change()。
5. hub_port_connect_change()
static void hub_port_connect_change(struct usb_hub *hub, int port1,
u16 portstatus, u16 portchange)
{
struct usb_device *hdev = hub->hdev; //这个值在usb_hcd_poll_rh_status()函数内部有操作
struct device *hub_dev = hub->intfdev;
struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
unsigned wHubCharacteristics =
le16_to_cpu(hub->descriptor->wHubCharacteristics);
struct usb_device *udev;
int status, i;
unsigned unit_load;
dev_dbg (hub_dev,
"port %d, status %04x, change %04x, %s\n",
port1, portstatus, portchange, portspeed(hub, portstatus));
if (hub->has_indicators) {
set_port_led(hub, port1, HUB_LED_AUTO);
hub->indicator[port1-1] = INDICATOR_AUTO;
}
#ifdef CONFIG_USB_OTG
/* during HNP, don't repeat the debounce */
if (hdev->bus->is_b_host)
portchange &= ~(USB_PORT_STAT_C_CONNECTION |
USB_PORT_STAT_C_ENABLE);
#endif
/* Try to resuscitate an existing device */
udev = hub->ports[port1 - 1]->child;
if ((portstatus & USB_PORT_STAT_CONNECTION) && udev &&
udev->state != USB_STATE_NOTATTACHED) {
usb_lock_device(udev);
if (portstatus & USB_PORT_STAT_ENABLE) {
status = 0; /* Nothing to do */
#ifdef CONFIG_PM_RUNTIME
} else if (udev->state == USB_STATE_SUSPENDED &&
udev->persist_enabled) {
/* For a suspended device, treat this as a
* remote wakeup event.
*/
status = usb_remote_wakeup(udev);
#endif
} else {
status = -ENODEV; /* Don't resuscitate */
}
usb_unlock_device(udev);
if (status == 0) {
clear_bit(port1, hub->change_bits);
return;
}
}
/* Disconnect any existing devices under this port */
if (udev) {
if (hcd->phy && !hdev->parent &&
!(portstatus & USB_PORT_STAT_CONNECTION))
usb_phy_notify_disconnect(hcd->phy, udev->speed);
usb_disconnect(&hub->ports[port1 - 1]->child);
}
clear_bit(port1, hub->change_bits);
/* We can forget about a "removed" device when there's a physical
* disconnect or the connect status changes.
*/
if (!(portstatus & USB_PORT_STAT_CONNECTION) || //端口状态为链接
(portchange & USB_PORT_STAT_C_CONNECTION)) //端口改变为链接
clear_bit(port1, hub->removed_bits);
if (portchange & (USB_PORT_STAT_C_CONNECTION |
USB_PORT_STAT_C_ENABLE)) {
status = hub_port_debounce_be_stable(hub, port1); //防抖处理
if (status < 0) {
if (status != -ENODEV && printk_ratelimit())
dev_err(hub_dev, "connect-debounce failed, "
"port %d disabled\n", port1);
portstatus &= ~USB_PORT_STAT_CONNECTION;
} else {
portstatus = status;
}
}
/* Return now if debouncing failed or nothing is connected or
* the device was "removed".
*/
if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
test_bit(port1, hub->removed_bits)) {
/* maybe switch power back on (e.g. root hub was reset) */
if ((wHubCharacteristics & HUB_CHAR_LPSM) < 2
&& !port_is_power_on(hub, portstatus))
set_port_feature(hdev, port1, USB_PORT_FEAT_POWER);
if (portstatus & USB_PORT_STAT_ENABLE)
goto done;
return;
}
if (hub_is_superspeed(hub->hdev))
unit_load = 150;
else
unit_load = 100;
status = 0;
for (i = 0; i < SET_CONFIG_TRIES; i++) {
/* reallocate for each attempt, since references
* to the previous one can escape in various ways
*/
udev = usb_alloc_dev(hdev, hdev->bus, port1); //分配一个usb设备
if (!udev) {
dev_err (hub_dev,
"couldn't allocate port %d usb_device\n",
port1);
goto done;
}
usb_set_device_state(udev, USB_STATE_POWERED);
udev->bus_mA = hub->mA_per_port;
udev->level = hdev->level + 1;
udev->wusb = hub_is_wusb(hub);
/* Only USB 3.0 devices are connected to SuperSpeed hubs. */
if (hub_is_superspeed(hub->hdev))
udev->speed = USB_SPEED_SUPER;
else
udev->speed = USB_SPEED_UNKNOWN;
choose_devnum(udev); //选择一个usb设备编号
if (udev->devnum <= 0) {
status = -ENOTCONN; /* Don't retry */
goto loop;
}
/* reset (non-USB 3.0 devices) and get descriptor */
status = hub_port_init(hub, udev, port1, i);
if (status < 0)
goto loop;
usb_detect_quirks(udev);
if (udev->quirks & USB_QUIRK_DELAY_INIT)
msleep(1000);
/* consecutive bus-powered hubs aren't reliable; they can
* violate the voltage drop budget. if the new child has
* a "powered" LED, users should notice we didn't enable it
* (without reading syslog), even without per-port LEDs
* on the parent.
*/
if (udev->descriptor.bDeviceClass == USB_CLASS_HUB
&& udev->bus_mA <= unit_load) {
u16 devstat;
status = usb_get_status(udev, USB_RECIP_DEVICE, 0,
&devstat);
if (status < 2) {
dev_dbg(&udev->dev, "get status %d ?\n", status);
goto loop_disable;
}
le16_to_cpus(&devstat);
if ((devstat & (1 << USB_DEVICE_SELF_POWERED)) == 0) {
dev_err(&udev->dev,
"can't connect bus-powered hub "
"to this port\n");
if (hub->has_indicators) {
hub->indicator[port1-1] =
INDICATOR_AMBER_BLINK;
schedule_delayed_work (&hub->leds, 0);
}
status = -ENOTCONN; /* Don't retry */
goto loop_disable;
}
}
/* check for devices running slower than they could */
if (le16_to_cpu(udev->descriptor.bcdUSB) >= 0x0200
&& udev->speed == USB_SPEED_FULL
&& highspeed_hubs != 0)
check_highspeed (hub, udev, port1);
/* Store the parent's children[] pointer. At this point
* udev becomes globally accessible, although presumably
* no one will look at it until hdev is unlocked.
*/
status = 0;
/* We mustn't add new devices if the parent hub has
* been disconnected; we would race with the
* recursively_mark_NOTATTACHED() routine.
*/
spin_lock_irq(&device_state_lock);
if (hdev->state == USB_STATE_NOTATTACHED)
status = -ENOTCONN;
else
hub->ports[port1 - 1]->child = udev;
spin_unlock_irq(&device_state_lock);
/* Run it through the hoops (find a driver, etc) */
if (!status) {
status = usb_new_device(udev); //新建一个usb设备
if (status) {
spin_lock_irq(&device_state_lock);
hub->ports[port1 - 1]->child = NULL;
spin_unlock_irq(&device_state_lock);
}
}
if (status)
goto loop_disable;
status = hub_power_remaining(hub);
if (status)
dev_dbg(hub_dev, "%dmA power budget left\n", status);
return;
loop_disable:
hub_port_disable(hub, port1, 1);
loop:
usb_ep0_reinit(udev);
release_devnum(udev);
hub_free_dev(udev);
usb_put_dev(udev);
if ((status == -ENOTCONN) || (status == -ENOTSUPP))
break;
}
if (hub->hdev->parent ||
!hcd->driver->port_handed_over ||
!(hcd->driver->port_handed_over)(hcd, port1)) {
if (status != -ENOTCONN && status != -ENODEV)
dev_err(hub_dev, "unable to enumerate USB device on port %d\n",
port1);
}
done:
hub_port_disable(hub, port1, 1);
if (hcd->driver->relinquish_port && !hub->hdev->parent)
hcd->driver->relinquish_port(hcd, port1);
}该函数通过对端口状态的改变进行端口连接状态的判定（包括是否重新复位端口、对端口防抖处理...），最后通过分配一个usb设备usb_alloc_dev()、选择设备编号choose_devnum(udev)， hub_port_init()端口初始化、usb_new_device()新建一个usb设备。
5.1 usb_alloc_dev()
struct usb_device *usb_alloc_dev(struct usb_device *parent,
struct usb_bus *bus, unsigned port1)
{
struct usb_device *dev;
struct usb_hcd *usb_hcd = bus_to_hcd(bus);
unsigned root_hub = 0;
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev)
return NULL;
if (!usb_get_hcd(usb_hcd)) {
kfree(dev);
return NULL;
}
/* Root hubs aren't true devices, so don't allocate HCD resources */
if (usb_hcd->driver->alloc_dev && parent &&
!usb_hcd->driver->alloc_dev(usb_hcd, dev)) {
usb_put_hcd(bus_to_hcd(bus));
kfree(dev);
return NULL;
}
device_initialize(&dev->dev);
dev->dev.bus = &usb_bus_type; //绑定设备的总线为“usb”
dev->dev.type = &usb_device_type; //设备的类型
dev->dev.groups = usb_device_groups;
dev->dev.dma_mask = bus->controller->dma_mask;
set_dev_node(&dev->dev, dev_to_node(bus->controller));
dev->state = USB_STATE_ATTACHED; //设置usb状态为绑定
dev->lpm_disable_count = 1;
atomic_set(&dev->urbnum, 0);
INIT_LIST_HEAD(&dev->ep0.urb_list);
dev->ep0.desc.bLength = USB_DT_ENDPOINT_SIZE; //设置断点长度
dev->ep0.desc.bDescriptorType = USB_DT_ENDPOINT; //设置端点描述符
/* ep0 maxpacket comes later, from device descriptor */
usb_enable_endpoint(dev, &dev->ep0, false);
dev->can_submit = 1;
/* Save readable and stable topology id, distinguishing devices
* by location for diagnostics, tools, driver model, etc. The
* string is a path along hub ports, from the root. Each device's
* dev->devpath will be stable until USB is re-cabled, and hubs
* are often labeled with these port numbers. The name isn't
* as stable: bus->busnum changes easily from modprobe order,
* cardbus or pci hotplugging, and so on.
*/
if (unlikely(!parent)) {
dev->devpath[0] = '0';
dev->route = 0;
dev->dev.parent = bus->controller;
dev_set_name(&dev->dev, "usb%d", bus->busnum);
root_hub = 1;
} else {
/* match any labeling on the hubs; it's one-based */
if (parent->devpath[0] == '0') {
snprintf(dev->devpath, sizeof dev->devpath,
"%d", port1);
/* Root ports are not counted in route string */
dev->route = 0;
} else {
snprintf(dev->devpath, sizeof dev->devpath,
"%s.%d", parent->devpath, port1);
/* Route string assumes hubs have less than 16 ports */
if (port1 < 15)
dev->route = parent->route +
(port1 << ((parent->level - 1)*4));
else
dev->route = parent->route +
(15 << ((parent->level - 1)*4));
}
dev->dev.parent = &parent->dev;
dev_set_name(&dev->dev, "%d-%s", bus->busnum, dev->devpath);
/* hub driver sets up TT records */
}
dev->portnum = port1;
dev->bus = bus;
dev->parent = parent;
INIT_LIST_HEAD(&dev->filelist);
#ifdef CONFIG_PM
pm_runtime_set_autosuspend_delay(&dev->dev,
usb_autosuspend_delay * 1000);
dev->connect_time = jiffies;
dev->active_duration = -jiffies;
#endif
if (root_hub) /* Root hub always ok [and always wired] */
dev->authorized = 1;
else {
dev->authorized = usb_hcd->authorized_default;
dev->wusb = usb_bus_is_wusb(bus)? 1 : 0;
}
return dev;
}
分配一个usb设备，包括绑定总线类型为usb，设备的类型为设备（非接口），设置端点0的描述符长度、类型，最后设置该设备的名称：dev_set_name(&dev->dev, "%d-%s", bus->busnum, dev->devpath)。
5.2 choose_devnum()
static void choose_devnum(struct usb_device *udev)
{
int devnum;
struct usb_bus *bus = udev->bus;
/* If khubd ever becomes multithreaded, this will need a lock */
if (udev->wusb) {
devnum = udev->portnum + 1;
BUG_ON(test_bit(devnum, bus->devmap.devicemap));
} else {
/* Try to allocate the next devnum beginning at
* bus->devnum_next. */
devnum = find_next_zero_bit(bus->devmap.devicemap, 128,
bus->devnum_next);
if (devnum >= 128)
devnum = find_next_zero_bit(bus->devmap.devicemap,
128, 1);
bus->devnum_next = ( devnum >= 127 ? 1 : devnum + 1);
}
if (devnum < 128) {
set_bit(devnum, bus->devmap.devicemap);
udev->devnum = devnum;
}
}
从bus->devmap.devicemap中分配一个未被占用的bit位作为当前分配的设备编号。
5.3 hub_port_init()
static int
hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
int retry_counter)
{
static DEFINE_MUTEX(usb_address0_mutex);
struct usb_device *hdev = hub->hdev;
struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
int i, j, retval;
unsigned delay = HUB_SHORT_RESET_TIME;
enum usb_device_speed oldspeed = udev->speed;
const char *speed;
int devnum = udev->devnum;
/* root hub ports have a slightly longer reset period
* (from USB 2.0 spec, section 7.1.7.5)
*/
if (!hdev->parent) {
delay = HUB_ROOT_RESET_TIME;
if (port1 == hdev->bus->otg_port)
hdev->bus->b_hnp_enable = 0;
}
/* Some low speed devices have problems with the quick delay, so */
/* be a bit pessimistic with those devices. RHbug #23670 */
if (oldspeed == USB_SPEED_LOW)
delay = HUB_LONG_RESET_TIME;
mutex_lock(&usb_address0_mutex);
/* Reset the device; full speed may morph to high speed */
/* FIXME a USB 2.0 device may morph into SuperSpeed on reset. */
retval = hub_port_reset(hub, port1, udev, delay, false); //复位设备
if (retval < 0) /* error or disconnect */
goto fail;
/* success, speed is known */
retval = -ENODEV;
if (oldspeed != USB_SPEED_UNKNOWN && oldspeed != udev->speed) {
dev_dbg(&udev->dev, "device reset changed speed!\n");
goto fail;
}
oldspeed = udev->speed;
/* USB 2.0 section 5.5.3 talks about ep0 maxpacket ...
* it's fixed size except for full speed devices.
* For Wireless USB devices, ep0 max packet is always 512 (tho
* reported as 0xff in the device descriptor). WUSB1.0[4.8.1].
*/
//先根据不同的速率，初始化传输包的字节数
switch (udev->speed) {
case USB_SPEED_SUPER:
case USB_SPEED_WIRELESS: /* fixed at 512 */
udev->ep0.desc.wMaxPacketSize = cpu_to_le16(512);
break;
case USB_SPEED_HIGH: /* fixed at 64 */
udev->ep0.desc.wMaxPacketSize = cpu_to_le16(64);
break;
case USB_SPEED_FULL: /* 8, 16, 32, or 64 */
/* to determine the ep0 maxpacket size, try to read
* the device descriptor to get bMaxPacketSize0 and
* then correct our initial guess.
*/
udev->ep0.desc.wMaxPacketSize = cpu_to_le16(64);
break;
case USB_SPEED_LOW: /* fixed at 8 */
udev->ep0.desc.wMaxPacketSize = cpu_to_le16(8);
break;
default:
goto fail;
}
if (udev->speed == USB_SPEED_WIRELESS)
speed = "variable speed Wireless";
else
speed = usb_speed_string(udev->speed);
if (udev->speed != USB_SPEED_SUPER)
dev_info(&udev->dev,
"%s %s USB device number %d using %s\n",
(udev->config) ? "reset" : "new", speed,
devnum, udev->bus->controller->driver->name);
/* Set up TT records, if needed */
//usb2.0与usb1.0、usb1.1转换
if (hdev->tt) {
udev->tt = hdev->tt;
udev->ttport = hdev->ttport;
} else if (udev->speed != USB_SPEED_HIGH
&& hdev->speed == USB_SPEED_HIGH) {
if (!hub->tt.hub) {
dev_err(&udev->dev, "parent hub has no TT\n");
retval = -EINVAL;
goto fail;
}
udev->tt = &hub->tt;
udev->ttport = port1;
}
/* Why interleave GET_DESCRIPTOR and SET_ADDRESS this way?
* Because device hardware and firmware is sometimes buggy in
* this area, and this is how Linux has done it for ages.
* Change it cautiously.
*
* NOTE: If USE_NEW_SCHEME() is true we will start by issuing
* a 64-byte GET_DESCRIPTOR request. This is what Windows does,
* so it may help with some non-standards-compliant devices.
* Otherwise we start with SET_ADDRESS and then try to read the
* first 8 bytes of the device descriptor to get the ep0 maxpacket
* value.
*/
//
for (i = 0; i < GET_DESCRIPTOR_TRIES; (++i, msleep(100))) {
if (USE_NEW_SCHEME(retry_counter) && !(hcd->driver->flags & HCD_USB3)) {
struct usb_device_descriptor *buf;
int r = 0;
#define GET_DESCRIPTOR_BUFSIZE 64
buf = kmalloc(GET_DESCRIPTOR_BUFSIZE, GFP_NOIO);
if (!buf) {
retval = -ENOMEM;
continue;
}
/* Retry on all errors; some devices are flakey.
* 255 is for WUSB devices, we actually need to use
* 512 (WUSB1.0[4.8.1]).
*/
for (j = 0; j < 3; ++j) {
buf->bMaxPacketSize0 = 0;
r = usb_control_msg(udev, usb_rcvaddr0pipe(), //获取64字节的设备描述符
USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
USB_DT_DEVICE << 8, 0,
buf, GET_DESCRIPTOR_BUFSIZE,
initial_descriptor_timeout);
switch (buf->bMaxPacketSize0) {
case 8: case 16: case 32: case 64: case 255:
if (buf->bDescriptorType ==
USB_DT_DEVICE) {
r = 0;
break;
}
/* FALL THROUGH */
default:
if (r == 0)
r = -EPROTO;
break;
}
if (r == 0)
break;
}
udev->descriptor.bMaxPacketSize0 =
buf->bMaxPacketSize0; //以当前获取到的设备描述符传输包的长度赋值
kfree(buf);
retval = hub_port_reset(hub, port1, udev, delay, false); //复位设备
if (retval < 0) /* error or disconnect */
goto fail;
if (oldspeed != udev->speed) {
dev_dbg(&udev->dev,
"device reset changed speed!\n");
retval = -ENODEV;
goto fail;
}
if (r) {
if (r != -ENODEV)
dev_err(&udev->dev, "device descriptor read/64, error %d\n",
r);
retval = -EMSGSIZE;
continue;
}
#undef GET_DESCRIPTOR_BUFSIZE
}
/*
* If device is WUSB, we already assigned an
* unauthorized address in the Connect Ack sequence;
* authorization will assign the final address.
*/
if (udev->wusb == 0) {
for (j = 0; j < SET_ADDRESS_TRIES; ++j) {
retval = hub_set_address(udev, devnum); //设置设备的地址为devnum
if (retval >= 0)
break;
msleep(200);
}
if (retval < 0) {
if (retval != -ENODEV)
dev_err(&udev->dev, "device not accepting address %d, error %d\n",
devnum, retval);
goto fail;
}
if (udev->speed == USB_SPEED_SUPER) {
devnum = udev->devnum;
dev_info(&udev->dev,
"%s SuperSpeed USB device number %d using %s\n",
(udev->config) ? "reset" : "new",
devnum, udev->bus->controller->driver->name);
}
/* cope with hardware quirkiness:
* - let SET_ADDRESS settle, some device hardware wants it
* - read ep0 maxpacket even for high and low speed,
*/
msleep(10);
if (USE_NEW_SCHEME(retry_counter) && !(hcd->driver->flags & HCD_USB3))
break;
}
retval = usb_get_device_descriptor(udev, 8); //获取长度为8个字节的设备描述，这是因为第8个字节的偏移为bMaxPacketSize0，而下面需要！！
if (retval < 8) {
if (retval != -ENODEV)
dev_err(&udev->dev,
"device descriptor read/8, error %d\n",
retval);
if (retval >= 0)
retval = -EMSGSIZE;
} else {
retval = 0;
break;
}
}
if (retval)
goto fail;
if (hcd->phy && !hdev->parent)
usb_phy_notify_connect(hcd->phy, udev->speed);
/*
* Some superspeed devices have finished the link training process
* and attached to a superspeed hub port, but the device descriptor
* got from those devices show they aren't superspeed devices. Warm
* reset the port attached by the devices can fix them.
*/
if ((udev->speed == USB_SPEED_SUPER) &&
(le16_to_cpu(udev->descriptor.bcdUSB) < 0x0300)) {
dev_err(&udev->dev, "got a wrong device descriptor, "
"warm reset device\n");
hub_port_reset(hub, port1, udev,
HUB_BH_RESET_TIME, true);
retval = -EINVAL;
goto fail;
}
if (udev->descriptor.bMaxPacketSize0 == 0xff ||
udev->speed == USB_SPEED_SUPER)
i = 512;
else
i = udev->descriptor.bMaxPacketSize0;
if (usb_endpoint_maxp(&udev->ep0.desc) != i) {
if (udev->speed == USB_SPEED_LOW ||
!(i == 8 || i == 16 || i == 32 || i == 64)) {
dev_err(&udev->dev, "Invalid ep0 maxpacket: %d\n", i);
retval = -EMSGSIZE;
goto fail;
}
if (udev->speed == USB_SPEED_FULL)
dev_dbg(&udev->dev, "ep0 maxpacket = %d\n", i);
else
dev_warn(&udev->dev, "Using ep0 maxpacket: %d\n", i);
udev->ep0.desc.wMaxPacketSize = cpu_to_le16(i);
usb_ep0_reinit(udev);
}
retval = usb_get_device_descriptor(udev, USB_DT_DEVICE_SIZE); //再次获取USB_DT_DEVICE_SIZE设备描述符的字节数
if (retval < (signed)sizeof(udev->descriptor)) {
if (retval != -ENODEV)
dev_err(&udev->dev, "device descriptor read/all, error %d\n",
retval);
if (retval >= 0)
retval = -ENOMSG;
goto fail;
}
if (udev->wusb == 0 && le16_to_cpu(udev->descriptor.bcdUSB) >= 0x0201) {
retval = usb_get_bos_descriptor(udev);
if (!retval) {
udev->lpm_capable = usb_device_supports_lpm(udev);
usb_set_lpm_parameters(udev);
}
}
retval = 0;
/* notify HCD that we have a device connected and addressed */
if (hcd->driver->update_device)
hcd->driver->update_device(hcd, udev);
fail:
if (retval) {
hub_port_disable(hub, port1, 0);
update_devnum(udev, devnum); /* for disconnect processing */
}
mutex_unlock(&usb_address0_mutex);
return retval;
}5. 4 usb_new_device() 设备枚举
int usb_new_device(struct usb_device *udev)
{
int err;
if (udev->parent) {
/* Initialize non-root-hub device wakeup to disabled;
* device (un)configuration controls wakeup capable
* sysfs power/wakeup controls wakeup enabled/disabled
*/
device_init_wakeup(&udev->dev, 0);
}
/* Tell the runtime-PM framework the device is active */
pm_runtime_set_active(&udev->dev);
pm_runtime_get_noresume(&udev->dev);
pm_runtime_use_autosuspend(&udev->dev);
pm_runtime_enable(&udev->dev);
/* By default, forbid autosuspend for all devices. It will be
* allowed for hubs during binding.
*/
usb_disable_autosuspend(udev);
//枚举设备
err = usb_enumerate_device(udev); /* Read descriptors */
if (err < 0)
goto fail;
dev_dbg(&udev->dev, "udev %d, busnum %d, minor = %d\n",
udev->devnum, udev->bus->busnum,
(((udev->bus->busnum-1) * 128) + (udev->devnum-1)));
/* export the usbdev device-node for libusb */
udev->dev.devt = MKDEV(USB_DEVICE_MAJOR,
(((udev->bus->busnum-1) * 128) + (udev->devnum-1)));
/* Tell the world! */
announce_device(udev);
if (udev->serial)
add_device_randomness(udev->serial, strlen(udev->serial));
if (udev->product)
add_device_randomness(udev->product, strlen(udev->product));
if (udev->manufacturer)
add_device_randomness(udev->manufacturer,
strlen(udev->manufacturer));
device_enable_async_suspend(&udev->dev);
/*
* check whether the hub marks this port as non-removable. Do it
* now so that platform-specific data can override it in
* device_add()
*/
if (udev->parent)
set_usb_port_removable(udev);
/* Register the device. The device driver is responsible
* for configuring the device and invoking the add-device
* notifier chain (used by usbfs and possibly others).
*/
err = device_add(&udev->dev);
if (err) {
dev_err(&udev->dev, "can't device_add, error %d\n", err);
goto fail;
}
/* Create link files between child device and usb port device. */
if (udev->parent) {
struct usb_hub *hub = usb_hub_to_struct_hub(udev->parent);
struct usb_port *port_dev = hub->ports[udev->portnum - 1];
err = sysfs_create_link(&udev->dev.kobj,
&port_dev->dev.kobj, "port");
if (err)
goto fail;
err = sysfs_create_link(&port_dev->dev.kobj,
&udev->dev.kobj, "device");
if (err) {
sysfs_remove_link(&udev->dev.kobj, "port");
goto fail;
}
pm_runtime_get_sync(&port_dev->dev);
}
(void) usb_create_ep_devs(&udev->dev, &udev->ep0, udev);
usb_mark_last_busy(udev);
pm_runtime_put_sync_autosuspend(&udev->dev);
return err;
fail:
usb_set_device_state(udev, USB_STATE_NOTATTACHED);
pm_runtime_disable(&udev->dev);
pm_runtime_set_suspended(&udev->dev);
return err;
}
该函数主要是通过usb_enumerate_device(udev)完成“设备枚举”（设备枚举的具体细节已经分析过，详见：点击打开链接， 5.6 小节），最后通过device_add(&udev->dev)将设备通添加到usb总线上，同时匹配对应的驱动，接下来将详细分析！！！
5.4.1 device_add()
int device_add(struct device *dev)
{
struct device *parent = NULL;
struct kobject *kobj;
struct class_interface *class_intf;
int error = -EINVAL;
dev = get_device(dev);
if (!dev)
goto done;
if (!dev->p) {
error = device_private_init(dev);
if (error)
goto done;
}
/*
* for statically allocated devices, which should all be converted
* some day, we need to initialize the name. We prevent reading back
* the name, and force the use of dev_name()
*/
if (dev->init_name) {
dev_set_name(dev, "%s", dev->init_name); //dev->init_name = "platform"
dev->init_name = NULL;
}
/* subsystems can specify simple device enumeration */
if (!dev_name(dev) && dev->bus && dev->bus->dev_name)
dev_set_name(dev, "%s%u", dev->bus->dev_name, dev->id);
if (!dev_name(dev)) {
error = -EINVAL;
goto name_error;
}
pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
parent = get_device(dev->parent); //dev->parent=platform_bus结构体
kobj = get_device_parent(dev, parent);
if (kobj)
dev->kobj.parent = kobj;
/* use parent numa_node */
if (parent)
set_dev_node(dev, dev_to_node(parent));
/* first, register with generic layer. */
/* we require the name to be set before, and pass NULL */
error = kobject_add(&dev->kobj, dev->kobj.parent, NULL); //对象增加，其实就是在文件系统/sys/device/platform下新建文件pinctrl
if (error)
goto Error;
/* notify platform of device entry */
if (platform_notify)
platform_notify(dev);
error = device_create_file(dev, &uevent_attr);
if (error)
goto attrError;
if (MAJOR(dev->devt)) {
error = device_create_file(dev, &devt_attr);
if (error)
goto ueventattrError;
error = device_create_sys_dev_entry(dev);
if (error)
goto devtattrError;
devtmpfs_create_node(dev);
}
error = device_add_class_symlinks(dev);
if (error)
goto SymlinkError;
error = device_add_attrs(dev);
if (error)
goto AttrsError;
error = bus_add_device(dev); //增加设备到总线上,是理解设备和驱动匹配的关键因素之一！
if (error)
goto BusError;
error = dpm_sysfs_add(dev);
if (error)
goto DPMError;
device_pm_add(dev);
/* Notify clients of device addition. This call must come
* after dpm_sysfs_add() and before kobject_uevent().
*/
if (dev->bus)
blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
BUS_NOTIFY_ADD_DEVICE, dev);
kobject_uevent(&dev->kobj, KOBJ_ADD); //kobject内核用户层事件增加
bus_probe_device(dev); //
if (parent)
klist_add_tail(&dev->p->knode_parent,
&parent->p->klist_children);
if (dev->class) {
mutex_lock(&dev->class->p->mutex);
/* tie the class to the device */
klist_add_tail(&dev->knode_class,
&dev->class->p->klist_devices);
/* notify any interfaces that the device is here */
list_for_each_entry(class_intf,
&dev->class->p->interfaces, node)
if (class_intf->add_dev)
class_intf->add_dev(dev, class_intf);
mutex_unlock(&dev->class->p->mutex);
}
done:
put_device(dev);
return error;
DPMError:
bus_remove_device(dev);
BusError:
device_remove_attrs(dev);
AttrsError:
device_remove_class_symlinks(dev);
SymlinkError:
if (MAJOR(dev->devt))
devtmpfs_delete_node(dev);
if (MAJOR(dev->devt))
device_remove_sys_dev_entry(dev);
devtattrError:
if (MAJOR(dev->devt))
device_remove_file(dev, &devt_attr);
ueventattrError:
device_remove_file(dev, &uevent_attr);
attrError:
kobject_uevent(&dev->kobj, KOBJ_REMOVE);
kobject_del(&dev->kobj);
Error:
cleanup_device_parent(dev);
if (parent)
put_device(parent);
name_error:
kfree(dev->p);
dev->p = NULL;
goto done;
}
该函数内部知识点较多，包括内核对象添加kobject_add()、sys文件系统属性绑定device_create_file()、将当前设备添加到usb总线的设备链表中bus_add_device()、最后通过bus_probe_device()匹配对应的驱动，这里将重点分析！
void bus_probe_device(struct device *dev)
{
struct bus_type *bus = dev->bus;
struct subsys_interface *sif;
int ret;
if (!bus)
return;
if (bus->p->drivers_autoprobe) { //在USB总线注册时，drivers_autoprobe已初始化为1
ret = device_attach(dev); //设备绑定，见下面分析
WARN_ON(ret < 0);
}
mutex_lock(&bus->p->mutex);
list_for_each_entry(sif, &bus->p->interfaces, node)
if (sif->add_dev)
sif->add_dev(dev, sif);
mutex_unlock(&bus->p->mutex);
}int device_attach(struct device *dev)
{
int ret = 0;
device_lock(dev);
//由于设备和驱动有对应的关系，一个设备只能对应一个驱动，而一个驱动可以对应
//多个设备，所以dev->driver为真就表示当前设备已经绑定了对应的驱动，否则就要
//遍历驱动链表寻找匹配的
if (dev->driver) {
if (klist_node_attached(&dev->p->knode_driver)) {
ret = 1;
goto out_unlock;
}
ret = device_bind_driver(dev); //确定是否绑定对应的驱动
if (ret == 0)
ret = 1;
else {
dev->driver = NULL;
ret = 0;
}
} else {
ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
pm_request_idle(dev);
}
out_unlock:
device_unlock(dev);
return ret;
}
EXPORT_SYMBOL_GPL(device_attach);由于设备和驱动有对应的关系，一个设备只能对应一个驱动，而一个驱动可以对应多个设备，所以dev->driver为真就表示当前设备已经绑定了对应的驱动，否则就要遍历驱动链表寻找匹配的，我们这里时第一次执行，所以条件不成立，要匹配新的驱动。
ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
void *data, int (*fn)(struct device_driver *, void *))
{
struct klist_iter i;
struct device_driver *drv;
int error = 0;
if (!bus)
return -EINVAL;
klist_iter_init_node(&bus->p->klist_drivers, &i,
start ? &start->p->knode_bus : NULL); //遍历usb总线上的驱动链表进行匹配
while ((drv = next_driver(&i)) && !error)
error = fn(drv, data);
klist_iter_exit(&i);
return error;
}
EXPORT_SYMBOL_GPL(bus_for_each_drv);该函数内部将遍历usb总线上的驱动链表，将当前设备与驱动进行匹配，这里调用回调函数__device_attach()，详见如下：
static int __device_attach(struct device_driver *drv, void *data)
{
struct device *dev = data;
if (!driver_match_device(drv, dev)) //驱动和设备匹配判定
return 0;
return driver_probe_device(drv, dev); //调用usb总线上的探测函数
}static inline int driver_match_device(struct device_driver *drv, struct device *dev)
{
return drv->bus->match ? drv->bus->match(dev, drv) : 1;
}这里的match函数将调用usb总线上的usb_device_match匹配函数，drv->bus->match=usb_bus_type.usb_device_match：
struct bus_type usb_bus_type = {
.name = "usb",
.match = usb_device_match, //将被调用
.uevent = usb_uevent,
};
static int usb_device_match(struct device *dev, struct device_driver *drv)
{
/* devices and interfaces are handled separately */
if (is_usb_device(dev)) { //是否是usb设备
/* 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)) { //是否是usb接口
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;
}在该函数内部我们这里匹配的时设备，所以执行if语句，在else语句内部是接口设备，我们知道，在usb驱动里真正与外设设备对应的时驱动而不是设备...现在在回到__device_attach函数内部的driver_probe_device()
int driver_probe_device(struct device_driver *drv, struct device *dev)
{
int ret = 0;
if (!device_is_registered(dev)) //判定当前设备是否已经注册过
return -ENODEV;
pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
drv->bus->name, __func__, dev_name(dev), drv->name);
pm_runtime_barrier(dev);
ret = really_probe(dev, drv); //调用真实的probe探测函数
pm_request_idle(dev);
return ret;
}static int really_probe(struct device *dev, struct device_driver *drv)
{
int ret = 0;
atomic_inc(&probe_count);
pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
drv->bus->name, __func__, drv->name, dev_name(dev));
WARN_ON(!list_empty(&dev->devres_head));
dev->driver = drv;
/* If using pinctrl, bind pins now before probing */
ret = pinctrl_bind_pins(dev); //待分析
if (ret)
goto probe_failed;
if (driver_sysfs_add(dev)) {
printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
__func__, dev_name(dev));
goto probe_failed;
}
if (dev->bus->probe) { //通过usb_driver_register(...)函数知道该条件不成立
ret = dev->bus->probe(dev);
if (ret)
goto probe_failed;
} else if (drv->probe) { //终于找到你了,哈哈哈！！！
ret = drv->probe(dev); //这里的probe函数就是usb驱动通用probe函数generic_probe
if (ret)
goto probe_failed;
}
driver_bound(dev);
ret = 1;
pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
drv->bus->name, __func__, dev_name(dev), drv->name);
goto done;
probe_failed:
devres_release_all(dev);
driver_sysfs_remove(dev);
dev->driver = NULL;
dev_set_drvdata(dev, NULL);
if (ret == -EPROBE_DEFER) {
/* Driver requested deferred probing */
dev_info(dev, "Driver %s requests probe deferral\n", drv->name);
driver_deferred_probe_add(dev);
} else if (ret != -ENODEV && ret != -ENXIO) {
/* driver matched but the probe failed */
printk(KERN_WARNING
"%s: probe of %s failed with error %d\n",
drv->name, dev_name(dev), ret);
} else {
pr_debug("%s: probe of %s rejects match %d\n",
drv->name, dev_name(dev), ret);
}
/*
* Ignore errors returned by ->probe so that the next driver can try
* its luck.
*/
ret = 0;
done:
atomic_dec(&probe_count);
wake_up(&probe_waitqueue);
return ret;
}
在该函数内部将usb通用驱动程序函数generic_probe，关于该函数的注册详见：点击打开链接，这里直接进入该函数内部分析。
6. generic_probe()
static int generic_probe(struct usb_device *udev)
{
int err, c;
/* Choose and set the configuration. This registers the interfaces
* with the driver core and lets interface drivers bind to them.
*/
if (udev->authorized == 0)
dev_err(&udev->dev, "Device is not authorized for usage\n");
else {
c = usb_choose_configuration(udev); //选择配置
if (c >= 0) {
err = usb_set_configuration(udev, c); //设置配置
if (err && err != -ENODEV) {
dev_err(&udev->dev, "can't set config #%d, error %d\n",
c, err);
/* This need not be fatal. The user can try to
* set other configurations. */
}
}
}
/* USB device state == configured ... usable */
usb_notify_add_device(udev);
return 0;
}6.1 usb_choose_configuration()
int usb_choose_configuration(struct usb_device *udev)
{
int i;
int num_configs;
int insufficient_power = 0;
struct usb_host_config *c, *best;
if (usb_device_is_owned(udev))
return 0;
best = NULL;
c = udev->config; //获取配置的指针
num_configs = udev->descriptor.bNumConfigurations; //通过打印的报文，确定配置个数为1个
for (i = 0; i < num_configs; (i++, c++)) {
struct usb_interface_descriptor *desc = NULL;
/* It's possible that a config has no interfaces! */
if (c->desc.bNumInterfaces > 0) //获取配置的接口数
desc = &c->intf_cache[0]->altsetting->desc;
/*
* HP's USB bus-powered keyboard has only one configuration
* and it claims to be self-powered; other devices may have
* similar errors in their descriptors. If the next test
* were allowed to execute, such configurations would always
* be rejected and the devices would not work as expected.
* In the meantime, we run the risk of selecting a config
* that requires external power at a time when that power
* isn't available. It seems to be the lesser of two evils.
*
* Bugzilla #6448 reports a device that appears to crash
* when it receives a GET_DEVICE_STATUS request! We don't
* have any other way to tell whether a device is self-powered,
* but since we don't use that information anywhere but here,
* the call has been removed.
*
* Maybe the GET_DEVICE_STATUS call and the test below can
* be reinstated when device firmwares become more reliable.
* Don't hold your breath.
*/
#if 0
/* Rule out self-powered configs for a bus-powered device */
if (bus_powered && (c->desc.bmAttributes &
USB_CONFIG_ATT_SELFPOWER))
continue;
#endif
/*
* The next test may not be as effective as it should be.
* Some hubs have errors in their descriptor, claiming
* to be self-powered when they are really bus-powered.
* We will overestimate the amount of current such hubs
* make available for each port.
*
* This is a fairly benign sort of failure. It won't
* cause us to reject configurations that we should have
* accepted.
*/
/* Rule out configs that draw too much bus current */
if (usb_get_max_power(udev, c) > udev->bus_mA) {
insufficient_power++;
continue;
}
/* When the first config's first interface is one of Microsoft's
* pet nonstandard Ethernet-over-USB protocols, ignore it unless
* this kernel has enabled the necessary host side driver.
* But: Don't ignore it if it's the only config.
*/
if (i == 0 && num_configs > 1 && desc &&
(is_rndis(desc) || is_activesync(desc))) {
#if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
continue;
#else
best = c;
#endif
}
/* From the remaining configs, choose the first one whose
* first interface is for a non-vendor-specific class.
* Reason: Linux is more likely to have a class driver
* than a vendor-specific driver. */
else if (udev->descriptor.bDeviceClass != //USB分配的设备类代码，0x01~0xfe为标准设备类，0xff为厂商自定义类型
USB_CLASS_VENDOR_SPEC &&
(desc && desc->bInterfaceClass !=
USB_CLASS_VENDOR_SPEC)) {
best = c;
break;
}
/* If all the remaining configs are vendor-specific,
* choose the first one. */
else if (!best)
best = c;
}
if (insufficient_power > 0)
dev_info(&udev->dev, "rejected %d configuration%s "
"due to insufficient available bus power\n",
insufficient_power, plural(insufficient_power));
if (best) {
i = best->desc.bConfigurationValue;
dev_dbg(&udev->dev,
"configuration #%d chosen from %d choice%s\n",
i, num_configs, plural(num_configs));
} else {
i = -1;
dev_warn(&udev->dev,
"no configuration chosen from %d choice%s\n",
num_configs, plural(num_configs));
}
return i;
}
6.2 usb_set_configuration(）
int usb_set_configuration(struct usb_device *dev, int configuration)
{
int i, ret;
struct usb_host_config *cp = NULL;
struct usb_interface **new_interfaces = NULL;
struct usb_hcd *hcd = bus_to_hcd(dev->bus);
int n, nintf;
if (dev->authorized == 0 || configuration == -1)
configuration = 0;
else {
for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
if (dev->config[i].desc.bConfigurationValue ==
configuration) { //在usb_choose_configuration()函数中返回了配置序号configuration，这里是通过配置序号找到对应的配置
cp = &dev->config[i];
break;
}
}
}
if ((!cp && configuration != 0))
return -EINVAL;
/* The USB spec says configuration 0 means unconfigured.
* But if a device includes a configuration numbered 0,
* we will accept it as a correctly configured state.
* Use -1 if you really want to unconfigure the device.
*/
if (cp && configuration == 0)
dev_warn(&dev->dev, "config 0 descriptor??\n");
/* Allocate memory for new interfaces before doing anything else,
* so that if we run out then nothing will have changed. */
n = nintf = 0;
if (cp) {
nintf = cp->desc.bNumInterfaces; //获取配置里的接口个数
new_interfaces = kmalloc(nintf * sizeof(*new_interfaces), //分配nintf个接口指针
GFP_NOIO);
if (!new_interfaces) {
dev_err(&dev->dev, "Out of memory\n");
return -ENOMEM;
}
//给每个接口分配内存空间
for (; n < nintf; ++n) { //遍历接口个数
new_interfaces[n] = kzalloc( //给每个接口分配空间
sizeof(struct usb_interface),
GFP_NOIO);
if (!new_interfaces[n]) {
dev_err(&dev->dev, "Out of memory\n");
ret = -ENOMEM;
free_interfaces:
while (--n >= 0)
kfree(new_interfaces[n]);
kfree(new_interfaces);
return ret;
}
}
i = dev->bus_mA - usb_get_max_power(dev, cp); //i = 枚举时获取到的电流-最大的标准电流
if (i < 0)
dev_warn(&dev->dev, "new config #%d exceeds power "
"limit by %dmA\n",
configuration, -i);
}
/* Wake up the device so we can send it the Set-Config request */
ret = usb_autoresume_device(dev);
if (ret)
goto free_interfaces;
/* if it's already configured, clear out old state first.
* getting rid of old interfaces means unbinding their drivers.
*/
if (dev->state != USB_STATE_ADDRESS)
usb_disable_device(dev, 1); /* Skip ep0 */
/* Get rid of pending async Set-Config requests for this device */
cancel_async_set_config(dev);
/* Make sure we have bandwidth (and available HCD resources) for this
* configuration. Remove endpoints from the schedule if we're dropping
* this configuration to set configuration 0. After this point, the
* host controller will not allow submissions to dropped endpoints. If
* this call fails, the device state is unchanged.
*/
mutex_lock(hcd->bandwidth_mutex);
/* Disable LPM, and re-enable it once the new configuration is
* installed, so that the xHCI driver can recalculate the U1/U2
* timeouts.
*/
if (dev->actconfig && usb_disable_lpm(dev)) {
dev_err(&dev->dev, "%s Failed to disable LPM\n.", __func__);
mutex_unlock(hcd->bandwidth_mutex);
ret = -ENOMEM;
goto free_interfaces;
}
ret = usb_hcd_alloc_bandwidth(dev, cp, NULL, NULL);
if (ret < 0) {
if (dev->actconfig)
usb_enable_lpm(dev);
mutex_unlock(hcd->bandwidth_mutex);
usb_autosuspend_device(dev);
goto free_interfaces;
}
/*
* Initialize the new interface structures and the
* hc/hcd/usbcore interface/endpoint state.
*/
//遍历接口，为初始化接口设备，绑定设备类型为接口！！！
for (i = 0; i < nintf; ++i) {
struct usb_interface_cache *intfc;
struct usb_interface *intf;
struct usb_host_interface *alt;
cp->interface[i] = intf = new_interfaces[i];
intfc = cp->intf_cache[i];
intf->altsetting = intfc->altsetting;
intf->num_altsetting = intfc->num_altsetting;
kref_get(&intfc->ref);
alt = usb_altnum_to_altsetting(intf, 0);
/* No altsetting 0? We'll assume the first altsetting.
* We could use a GetInterface call, but if a device is
* so non-compliant that it doesn't have altsetting 0
* then I wouldn't trust its reply anyway.
*/
if (!alt)
alt = &intf->altsetting[0];
intf->intf_assoc =
find_iad(dev, cp, alt->desc.bInterfaceNumber);
intf->cur_altsetting = alt;
usb_enable_interface(dev, intf, true);
intf->dev.parent = &dev->dev;
intf->dev.driver = NULL;
intf->dev.bus = &usb_bus_type; //将当前设备绑定总线为USB
intf->dev.type = &usb_if_device_type; //设备类型为接口
intf->dev.groups = usb_interface_groups; //usb接口类型为组
intf->dev.dma_mask = dev->dev.dma_mask;
INIT_WORK(&intf->reset_ws, __usb_queue_reset_device);
intf->minor = -1;
device_initialize(&intf->dev); //设备模型初始化
pm_runtime_no_callbacks(&intf->dev);
dev_set_name(&intf->dev, "%d-%s:%d.%d",
dev->bus->busnum, dev->devpath,
configuration, alt->desc.bInterfaceNumber);
}
kfree(new_interfaces);
//设置主机控制器上的配置索引
ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
USB_REQ_SET_CONFIGURATION, 0, configuration, 0,
NULL, 0, USB_CTRL_SET_TIMEOUT);
if (ret < 0 && cp) {
/*
* All the old state is gone, so what else can we do?
* The device is probably useless now anyway.
*/
usb_hcd_alloc_bandwidth(dev, NULL, NULL, NULL);
for (i = 0; i < nintf; ++i) {
usb_disable_interface(dev, cp->interface[i], true);
put_device(&cp->interface[i]->dev);
cp->interface[i] = NULL;
}
cp = NULL;
}
dev->actconfig = cp; //绑定实际的配置
mutex_unlock(hcd->bandwidth_mutex);
if (!cp) {
usb_set_device_state(dev, USB_STATE_ADDRESS);
/* Leave LPM disabled while the device is unconfigured. */
usb_autosuspend_device(dev);
return ret;
}
usb_set_device_state(dev, USB_STATE_CONFIGURED);
if (cp->string == NULL &&
!(dev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
cp->string = usb_cache_string(dev, cp->desc.iConfiguration);
/* Now that the interfaces are installed, re-enable LPM. */
usb_unlocked_enable_lpm(dev);
/* Enable LTM if it was turned off by usb_disable_device. */
usb_enable_ltm(dev);
/* Now that all the interfaces are set up, register them
* to trigger binding of drivers to interfaces. probe()
* routines may install different altsettings and may
* claim() any interfaces not yet bound. Many class drivers
* need that: CDC, audio, video, etc.
*/
//遍历接口，注册接口到usb总线上，同时匹配对应的驱动
for (i = 0; i < nintf; ++i) {
struct usb_interface *intf = cp->interface[i];
dev_dbg(&dev->dev,
"adding %s (config #%d, interface %d)\n",
dev_name(&intf->dev), configuration,
intf->cur_altsetting->desc.bInterfaceNumber);
device_enable_async_suspend(&intf->dev);
ret = device_add(&intf->dev); //又是熟悉的接口函数
if (ret != 0) {
dev_err(&dev->dev, "device_add(%s) --> %d\n",
dev_name(&intf->dev), ret);
continue;
}
create_intf_ep_devs(intf);
}
usb_autosuspend_device(dev);
return 0;
}intf->dev.bus = &usb_bus_type; //将当前设备绑定总线为USB
intf->dev.type = &usb_if_device_type; //设备类型为接口
intf->dev.groups = usb_interface_groups; //usb接口类型为组
......
ret = device_add(&intf->dev);static int usb_device_match(struct device *dev, struct device_driver *drv)
{
/* devices and interfaces are handled separately */
if (is_usb_device(dev)) { //是否是usb设备
/* 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)) { //是否是usb接口
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)) //条件过滤
return 0;
intf = to_usb_interface(dev);
usb_drv = to_usb_driver(drv);
id = usb_match_id(intf, usb_drv->id_table); //将当前接口与对应的驱动id_table表进行匹配
if (id)
return 1;
id = usb_match_dynamic_id(intf, usb_drv);
if (id)
return 1;
}
return 0;
} id = usb_match_id(intf, usb_drv->id_table); //将当前接口与对应的驱动id_table表进行匹配7. usb_match_id()接口匹配
const struct usb_device_id *usb_match_id(struct usb_interface *interface,
const struct usb_device_id *id)
{
/* proc_connectinfo in devio.c may call us with id == NULL. */
if (id == NULL)
return NULL;
/* It is important to check that id->driver_info is nonzero,
since an entry that is all zeroes except for a nonzero
id->driver_info is the way to create an entry that
indicates that the driver want to examine every
device and interface. */
for (; id->idVendor || id->idProduct || id->bDeviceClass ||
id->bInterfaceClass || id->driver_info; id++) {
if (usb_match_one_id(interface, id)) //见下分析
return id;
}
return NULL;
}
EXPORT_SYMBOL_GPL(usb_match_id);int usb_match_device(struct usb_device *dev, const struct usb_device_id *id)
{
if ((id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
id->idVendor != le16_to_cpu(dev->descriptor.idVendor))
return 0;
if ((id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT) &&
id->idProduct != le16_to_cpu(dev->descriptor.idProduct))
return 0;
/* No need to test id->bcdDevice_lo != 0, since 0 is never
greater than any unsigned number. */
if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO) &&
(id->bcdDevice_lo > le16_to_cpu(dev->descriptor.bcdDevice)))
return 0;
if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI) &&
(id->bcdDevice_hi < le16_to_cpu(dev->descriptor.bcdDevice)))
return 0;
if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS) &&
(id->bDeviceClass != dev->descriptor.bDeviceClass))
return 0;
if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_SUBCLASS) &&
(id->bDeviceSubClass != dev->descriptor.bDeviceSubClass))
return 0;
if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_PROTOCOL) &&
(id->bDeviceProtocol != dev->descriptor.bDeviceProtocol))
return 0;
return 1;
}8. usb_probe_interface()接口探测函数
static int usb_probe_interface(struct device *dev)
{
struct usb_driver *driver = to_usb_driver(dev->driver);
struct usb_interface *intf = to_usb_interface(dev);
struct usb_device *udev = interface_to_usbdev(intf);
const struct usb_device_id *id;
int error = -ENODEV;
int lpm_disable_error;
dev_dbg(dev, "%s\n", __func__);
intf->needs_binding = 0;
if (usb_device_is_owned(udev))
return error;
if (udev->authorized == 0) {
dev_err(&intf->dev, "Device is not authorized for usage\n");
return error;
}
id = usb_match_id(intf, driver->id_table); //driver->id_table是哪里赋值的？？？
if (!id)
id = usb_match_dynamic_id(intf, driver);
if (!id)
return error;
dev_dbg(dev, "%s - got id\n", __func__);
error = usb_autoresume_device(udev);
if (error)
return error;
intf->condition = USB_INTERFACE_BINDING;
/* Probed interfaces are initially active. They are
* runtime-PM-enabled only if the driver has autosuspend support.
* They are sensitive to their children's power states.
*/
pm_runtime_set_active(dev);
pm_suspend_ignore_children(dev, false);
if (driver->supports_autosuspend)
pm_runtime_enable(dev);
/* If the new driver doesn't allow hub-initiated LPM, and we can't
* disable hub-initiated LPM, then fail the probe.
*
* Otherwise, leaving LPM enabled should be harmless, because the
* endpoint intervals should remain the same, and the U1/U2 timeouts
* should remain the same.
*
* If we need to install alt setting 0 before probe, or another alt
* setting during probe, that should also be fine. usb_set_interface()
* will attempt to disable LPM, and fail if it can't disable it.
*/
lpm_disable_error = usb_unlocked_disable_lpm(udev);
if (lpm_disable_error && driver->disable_hub_initiated_lpm) {
dev_err(&intf->dev, "%s Failed to disable LPM for driver %s\n.",
__func__, driver->name);
error = lpm_disable_error;
goto err;
}
/* Carry out a deferred switch to altsetting 0 */
if (intf->needs_altsetting0) {
error = usb_set_interface(udev, intf->altsetting[0].
desc.bInterfaceNumber, 0);
if (error < 0)
goto err;
intf->needs_altsetting0 = 0;
}
error = driver->probe(intf, id); //这里将调用usb_serial_probe()
if (error)
goto err;
intf->condition = USB_INTERFACE_BOUND;
/* If the LPM disable succeeded, balance the ref counts. */
if (!lpm_disable_error)
usb_unlocked_enable_lpm(udev);
usb_autosuspend_device(udev);
return error;
err:
usb_set_intfdata(intf, NULL);
intf->needs_remote_wakeup = 0;
intf->condition = USB_INTERFACE_UNBOUND;
usb_cancel_queued_reset(intf);
/* If the LPM disable succeeded, balance the ref counts. */
if (!lpm_disable_error)
usb_unlocked_enable_lpm(udev);
/* Unbound interfaces are always runtime-PM-disabled and -suspended */
if (driver->supports_autosuspend)
pm_runtime_disable(dev);
pm_runtime_set_suspended(dev);
usb_autosuspend_device(udev);
return error;
}该接口探测函数的主要功能是通过usb_match_id(intf, driver->id_table)，从id_table表中匹配与接口对应的id，如果成功将调用如下探测函数指针：
error = driver->probe(intf, id); //这里将调用usb_serial_probe()9. usb_serial_probe() usb串口探测函数
static int usb_serial_probe(struct usb_interface *interface,
const struct usb_device_id *id)
{
struct device *ddev = &interface->dev;
struct usb_device *dev = interface_to_usbdev(interface);
struct usb_serial *serial = NULL;
struct usb_serial_port *port;
struct usb_host_interface *iface_desc;
struct usb_endpoint_descriptor *endpoint;
struct usb_endpoint_descriptor *interrupt_in_endpoint[MAX_NUM_PORTS];
struct usb_endpoint_descriptor *interrupt_out_endpoint[MAX_NUM_PORTS];
struct usb_endpoint_descriptor *bulk_in_endpoint[MAX_NUM_PORTS];
struct usb_endpoint_descriptor *bulk_out_endpoint[MAX_NUM_PORTS];
struct usb_serial_driver *type = NULL;
int retval;
unsigned int minor;
int buffer_size;
int i;
int j;
int num_interrupt_in = 0;
int num_interrupt_out = 0;
int num_bulk_in = 0;
int num_bulk_out = 0;
int num_ports = 0;
int max_endpoints;
mutex_lock(&table_lock);
type = search_serial_device(interface); //根据接口，从usb_serial_driver_list链表中搜索匹配的id对应的驱动
if (!type) {
mutex_unlock(&table_lock);
dev_dbg(ddev, "none matched\n");
return -ENODEV;
}
if (!try_module_get(type->driver.owner)) {
mutex_unlock(&table_lock);
dev_err(ddev, "module get failed, exiting\n");
return -EIO;
}
mutex_unlock(&table_lock);
serial = create_serial(dev, interface, type);
if (!serial) {
module_put(type->driver.owner);
return -ENOMEM;
}
/* if this device type has a probe function, call it */
if (type->probe) {
const struct usb_device_id *id;
id = get_iface_id(type, interface);
retval = type->probe(serial, id); //调用上面匹配到的驱动探测函数
if (retval) {
dev_dbg(ddev, "sub driver rejected device\n");
usb_serial_put(serial);
module_put(type->driver.owner);
return retval;
}
}
/* descriptor matches, let's find the endpoints needed */
/* check out the endpoints */
iface_desc = interface->cur_altsetting;
for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
endpoint = &iface_desc->endpoint[i].desc;
if (usb_endpoint_is_bulk_in(endpoint)) {
/* we found a bulk in endpoint */
dev_dbg(ddev, "found bulk in on endpoint %d\n", i);
bulk_in_endpoint[num_bulk_in] = endpoint;
++num_bulk_in;
}
if (usb_endpoint_is_bulk_out(endpoint)) {
/* we found a bulk out endpoint */
dev_dbg(ddev, "found bulk out on endpoint %d\n", i);
bulk_out_endpoint[num_bulk_out] = endpoint;
++num_bulk_out;
}
if (usb_endpoint_is_int_in(endpoint)) {
/* we found a interrupt in endpoint */
dev_dbg(ddev, "found interrupt in on endpoint %d\n", i);
interrupt_in_endpoint[num_interrupt_in] = endpoint;
++num_interrupt_in;
}
if (usb_endpoint_is_int_out(endpoint)) {
/* we found an interrupt out endpoint */
dev_dbg(ddev, "found interrupt out on endpoint %d\n", i);
interrupt_out_endpoint[num_interrupt_out] = endpoint;
++num_interrupt_out;
}
}
#if defined(CONFIG_USB_SERIAL_PL2303) || defined(CONFIG_USB_SERIAL_PL2303_MODULE)
/* BEGIN HORRIBLE HACK FOR PL2303 */
/* this is needed due to the looney way its endpoints are set up */
if (((le16_to_cpu(dev->descriptor.idVendor) == PL2303_VENDOR_ID) &&
(le16_to_cpu(dev->descriptor.idProduct) == PL2303_PRODUCT_ID)) ||
((le16_to_cpu(dev->descriptor.idVendor) == ATEN_VENDOR_ID) &&
(le16_to_cpu(dev->descriptor.idProduct) == ATEN_PRODUCT_ID)) ||
((le16_to_cpu(dev->descriptor.idVendor) == ALCOR_VENDOR_ID) &&
(le16_to_cpu(dev->descriptor.idProduct) == ALCOR_PRODUCT_ID)) ||
((le16_to_cpu(dev->descriptor.idVendor) == SIEMENS_VENDOR_ID) &&
(le16_to_cpu(dev->descriptor.idProduct) == SIEMENS_PRODUCT_ID_EF81))) {
if (interface != dev->actconfig->interface[0]) {
/* check out the endpoints of the other interface*/
iface_desc = dev->actconfig->interface[0]->cur_altsetting;
for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
endpoint = &iface_desc->endpoint[i].desc;
if (usb_endpoint_is_int_in(endpoint)) {
/* we found a interrupt in endpoint */
dev_dbg(ddev, "found interrupt in for Prolific device on separate interface\n");
interrupt_in_endpoint[num_interrupt_in] = endpoint;
++num_interrupt_in;
}
}
}
/* Now make sure the PL-2303 is configured correctly.
* If not, give up now and hope this hack will work
* properly during a later invocation of usb_serial_probe
*/
if (num_bulk_in == 0 || num_bulk_out == 0) {
dev_info(ddev, "PL-2303 hack: descriptors matched but endpoints did not\n");
usb_serial_put(serial);
module_put(type->driver.owner);
return -ENODEV;
}
}
/* END HORRIBLE HACK FOR PL2303 */
#endif
#ifdef CONFIG_USB_SERIAL_GENERIC
if (type == &usb_serial_generic_device) {
num_ports = num_bulk_out;
if (num_ports == 0) {
dev_err(ddev, "Generic device with no bulk out, not allowed.\n");
usb_serial_put(serial);
module_put(type->driver.owner);
return -EIO;
}
dev_info(ddev, "The \"generic\" usb-serial driver is only for testing and one-off prototypes.\n");
dev_info(ddev, "Tell [email protected] to add your device to a proper driver.\n");
}
#endif
if (!num_ports) {
/* if this device type has a calc_num_ports function, call it */
if (type->calc_num_ports)
num_ports = type->calc_num_ports(serial);
if (!num_ports)
num_ports = type->num_ports;
}
serial->num_ports = num_ports;
serial->num_bulk_in = num_bulk_in;
serial->num_bulk_out = num_bulk_out;
serial->num_interrupt_in = num_interrupt_in;
serial->num_interrupt_out = num_interrupt_out;
/* found all that we need */
dev_info(ddev, "%s converter detected\n", type->description);
/* create our ports, we need as many as the max endpoints */
/* we don't use num_ports here because some devices have more
endpoint pairs than ports */
max_endpoints = max(num_bulk_in, num_bulk_out);
max_endpoints = max(max_endpoints, num_interrupt_in);
max_endpoints = max(max_endpoints, num_interrupt_out);
max_endpoints = max(max_endpoints, (int)serial->num_ports);
serial->num_port_pointers = max_endpoints;
dev_dbg(ddev, "setting up %d port structures for this device", max_endpoints);
for (i = 0; i < max_endpoints; ++i) {
port = kzalloc(sizeof(struct usb_serial_port), GFP_KERNEL);
if (!port)
goto probe_error;
tty_port_init(&port->port);
port->port.ops = &serial_port_ops;
port->serial = serial;
spin_lock_init(&port->lock);
/* Keep this for private driver use for the moment but
should probably go away */
INIT_WORK(&port->work, usb_serial_port_work);
serial->port[i] = port;
port->dev.parent = &interface->dev;
port->dev.driver = NULL;
port->dev.bus = &usb_serial_bus_type;
port->dev.release = &usb_serial_port_release;
device_initialize(&port->dev);
}
/* set up the endpoint information */
for (i = 0; i < num_bulk_in; ++i) {
endpoint = bulk_in_endpoint[i];
port = serial->port[i];
buffer_size = max_t(int, serial->type->bulk_in_size,
usb_endpoint_maxp(endpoint));
port->bulk_in_size = buffer_size;
port->bulk_in_endpointAddress = endpoint->bEndpointAddress;
for (j = 0; j < ARRAY_SIZE(port->read_urbs); ++j) {
set_bit(j, &port->read_urbs_free);
port->read_urbs[j] = usb_alloc_urb(0, GFP_KERNEL);
if (!port->read_urbs[j])
goto probe_error;
port->bulk_in_buffers[j] = kmalloc(buffer_size,
GFP_KERNEL);
if (!port->bulk_in_buffers[j])
goto probe_error;
usb_fill_bulk_urb(port->read_urbs[j], dev,
usb_rcvbulkpipe(dev,
endpoint->bEndpointAddress),
port->bulk_in_buffers[j], buffer_size,
serial->type->read_bulk_callback,
port);
}
port->read_urb = port->read_urbs[0];
port->bulk_in_buffer = port->bulk_in_buffers[0];
}
for (i = 0; i < num_bulk_out; ++i) {
endpoint = bulk_out_endpoint[i];
port = serial->port[i];
if (kfifo_alloc(&port->write_fifo, PAGE_SIZE, GFP_KERNEL))
goto probe_error;
buffer_size = serial->type->bulk_out_size;
if (!buffer_size)
buffer_size = usb_endpoint_maxp(endpoint);
port->bulk_out_size = buffer_size;
port->bulk_out_endpointAddress = endpoint->bEndpointAddress;
for (j = 0; j < ARRAY_SIZE(port->write_urbs); ++j) {
set_bit(j, &port->write_urbs_free);
port->write_urbs[j] = usb_alloc_urb(0, GFP_KERNEL);
if (!port->write_urbs[j])
goto probe_error;
port->bulk_out_buffers[j] = kmalloc(buffer_size,
GFP_KERNEL);
if (!port->bulk_out_buffers[j])
goto probe_error;
usb_fill_bulk_urb(port->write_urbs[j], dev,
usb_sndbulkpipe(dev,
endpoint->bEndpointAddress),
port->bulk_out_buffers[j], buffer_size,
serial->type->write_bulk_callback,
port);
}
port->write_urb = port->write_urbs[0];
port->bulk_out_buffer = port->bulk_out_buffers[0];
}
if (serial->type->read_int_callback) {
for (i = 0; i < num_interrupt_in; ++i) {
endpoint = interrupt_in_endpoint[i];
port = serial->port[i];
port->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
if (!port->interrupt_in_urb)
goto probe_error;
buffer_size = usb_endpoint_maxp(endpoint);
port->interrupt_in_endpointAddress =
endpoint->bEndpointAddress;
port->interrupt_in_buffer = kmalloc(buffer_size,
GFP_KERNEL);
if (!port->interrupt_in_buffer)
goto probe_error;
usb_fill_int_urb(port->interrupt_in_urb, dev,
usb_rcvintpipe(dev,
endpoint->bEndpointAddress),
port->interrupt_in_buffer, buffer_size,
serial->type->read_int_callback, port,
endpoint->bInterval);
}
} else if (num_interrupt_in) {
dev_dbg(ddev, "The device claims to support interrupt in transfers, but read_int_callback is not defined\n");
}
if (serial->type->write_int_callback) {
for (i = 0; i < num_interrupt_out; ++i) {
endpoint = interrupt_out_endpoint[i];
port = serial->port[i];
port->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
if (!port->interrupt_out_urb)
goto probe_error;
buffer_size = usb_endpoint_maxp(endpoint);
port->interrupt_out_size = buffer_size;
port->interrupt_out_endpointAddress =
endpoint->bEndpointAddress;
port->interrupt_out_buffer = kmalloc(buffer_size,
GFP_KERNEL);
if (!port->interrupt_out_buffer)
goto probe_error;
usb_fill_int_urb(port->interrupt_out_urb, dev,
usb_sndintpipe(dev,
endpoint->bEndpointAddress),
port->interrupt_out_buffer, buffer_size,
serial->type->write_int_callback, port,
endpoint->bInterval);
}
} else if (num_interrupt_out) {
dev_dbg(ddev, "The device claims to support interrupt out transfers, but write_int_callback is not defined\n");
}
usb_set_intfdata(interface, serial);
/* if this device type has an attach function, call it */
if (type->attach) {
retval = type->attach(serial);
if (retval < 0)
goto probe_error;
serial->attached = 1;
if (retval > 0) {
/* quietly accept this device, but don't bind to a
serial port as it's about to disappear */
serial->num_ports = 0;
goto exit;
}
} else {
serial->attached = 1;
}
/* Avoid race with tty_open and serial_install by setting the
* disconnected flag and not clearing it until all ports have been
* registered.
*/
serial->disconnected = 1;
if (get_free_serial(serial, num_ports, &minor) == NULL) {
dev_err(ddev, "No more free serial devices\n");
goto probe_error;
}
serial->minor = minor;
/* register all of the individual ports with the driver core */
for (i = 0; i < num_ports; ++i) {
port = serial->port[i];
dev_set_name(&port->dev, "ttyUSB%d", port->number);
dev_dbg(ddev, "registering %s", dev_name(&port->dev));
device_enable_async_suspend(&port->dev);
retval = device_add(&port->dev);
if (retval)
dev_err(ddev, "Error registering port device, continuing\n");
}
serial->disconnected = 0;
usb_serial_console_init(minor);
exit:
module_put(type->driver.owner);
return 0;
probe_error:
usb_serial_put(serial);
module_put(type->driver.owner);
return -EIO;
}static struct usb_serial_driver *search_serial_device(
struct usb_interface *iface)
{
const struct usb_device_id *id = NULL;
struct usb_serial_driver *drv;
struct usb_driver *driver = to_usb_driver(iface->dev.driver);
/* Check if the usb id matches a known device */
list_for_each_entry(drv, &usb_serial_driver_list, driver_list) {
if (drv->usb_driver == driver)
id = get_iface_id(drv, iface); //见下
if (id)
return drv;
}
return NULL;
}static const struct usb_device_id *get_iface_id(struct usb_serial_driver *drv,
struct usb_interface *intf)
{
const struct usb_device_id *id;
id = usb_match_id(intf, drv->id_table);
if (id) {
dev_dbg(&intf->dev, "static descriptor matches\n");
goto exit;
}
id = match_dynamic_id(intf, drv);
if (id)
dev_dbg(&intf->dev, "dynamic descriptor matches\n");
exit:
return id;
} if (type->probe) {
const struct usb_device_id *id;
id = get_iface_id(type, interface);
retval = type->probe(serial, id); //调用上面匹配到的驱动探测函数
if (retval) {
dev_dbg(ddev, "sub driver rejected device\n");
usb_serial_put(serial);
module_put(type->driver.owner);
return retval;
}
}
我们再回到上面的函数：
retval = type->probe(serial, id); //调用上面匹配到的驱动探测函数这里将调用options.c的探测函数，这个函数也是我们最终的根源，不容易！！！
10. option_probe()
static int option_probe(struct usb_serial *serial,
const struct usb_device_id *id)
{
struct usb_interface_descriptor *iface_desc =
&serial->interface->cur_altsetting->desc;
struct usb_device_descriptor *dev_desc = &serial->dev->descriptor;
/* Never bind to the CD-Rom emulation interface */
if (iface_desc->bInterfaceClass == 0x08)
return -ENODEV;
/*
* Don't bind reserved interfaces (like network ones) which often have
* the same class/subclass/protocol as the serial interfaces. Look at
* the Windows driver .INF files for reserved interface numbers.
*/
if (is_blacklisted(
iface_desc->bInterfaceNumber,
OPTION_BLACKLIST_RESERVED_IF,
(const struct option_blacklist_info *) id->driver_info))
return -ENODEV;
/*
* Don't bind network interface on Samsung GT-B3730, it is handled by
* a separate module.
*/
if (dev_desc->idVendor == cpu_to_le16(SAMSUNG_VENDOR_ID) &&
dev_desc->idProduct == cpu_to_le16(SAMSUNG_PRODUCT_GT_B3730) &&
iface_desc->bInterfaceClass != USB_CLASS_CDC_DATA)
return -ENODEV;
/* Store device id so we can use it during attach. */
usb_set_serial_data(serial, (void *)id);
return 0;
}