学网站开发顺序,网站设计考虑因素,推广平台下载,附近量身定做衣服店系列文章目录 xHCI 简单分析 USB Root Hub 分析 USB Hub 检测设备 文章目录 系列文章目录一、引言二、hub_eventshub_port_connect_changeusb_alloc_devusb_set_device_statehub_port_initusb_new_device 一、引言 USB Hub 检测设备 一文中讲到#xff0c;当有 USB 插入时当有 USB 插入时它会激活 hub_events 函数。
static int hub_thread(void *__unused)
{do {hub_events();wait_event_interruptible(khubd_wait,!list_empty(hub_event_list) ||kthread_should_stop());try_to_freeze();} while (!kthread_should_stop() || !list_empty(hub_event_list));pr_debug(%s: khubd exiting\n, usbcore_name);return 0;
}二、hub_events static void hub_events(void)
{// ...while (1) {// ...tmp hub_event_list.next;list_del_init(tmp);hub list_entry(tmp, struct usb_hub, event_list);// 描述 usb 设备Hub整体不是接口hdev hub-hdev;intf to_usb_interface(hub-intfdev);// hub 接口设备hub_dev intf-dev;// .../* Lock the device, then check to see if we were* disconnected while waiting for the lock to succeed. */if (locktree(hdev) 0) {// .../* Autoresume */ret usb_autopm_get_interface(intf);// .../* deal with port status changes */for (i 1; i hub-descriptor-bNbrPorts; i) {// ...ret hub_port_status(hub, i,portstatus, portchange);// ...if (connect_change)hub_port_connect_change(hub, i,portstatus, portchange);} /* end for i */// ...if (!hdev-parent !hub-busy_bits[0])usb_enable_root_hub_irq(hdev-bus);loop_autopm:/* Allow autosuspend if were not going to run again */if (list_empty(hub-event_list))usb_autopm_enable(intf);
loop:usb_unlock_device(hdev);usb_put_intf(intf);} /* end while (1) */
}在这个循环中检测 Hub 的每个端口是否有变化有变化则调用 hub_port_connect_change 进行处理。
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;struct device *hub_dev hub-intfdev;// .../* Disconnect any existing devices under this port */if (hdev-children[port1-1])usb_disconnect(hdev-children[port1-1]);clear_bit(port1, hub-change_bits);// ...for (i 0; i SET_CONFIG_TRIES; i) {struct usb_device *udev;// ...udev usb_alloc_dev(hdev, hdev-bus, port1);// ...usb_set_device_state(udev, USB_STATE_POWERED);udev-speed USB_SPEED_UNKNOWN;udev-bus_mA hub-mA_per_port;udev-level hdev-level 1;// ...choose_address(udev);// .../* reset and get descriptor */status hub_port_init(hub, udev, port1, i);// ...if (!status) {status usb_new_device(udev);// ...}// ...status hub_power_remaining(hub);// ...
}在这个循环中主要涉及 8 个重量级函数先点明它们的角色分工。 第一个函数usb_alloc_dev()一个 struct usb_device 结构体指针申请内存这个结构体指针可不是为 Hub 准备的它正是为了 Hub 这个端口所接的设备而申请的别忘了我们此时此刻的上下文之所以进入这个循环是因为我们的 Hub 检测到某个端口有设备连接所以Hub 驱动就义不容辞地要为该设备做点什么。 第二个函数usb_set_device_state()这个函数用来设置设备的状态在 struct usb_device 结构体中有一个成员 enum usb_device_state state这一刻会把这个设备的状态设置为 USB_STATE_POWERED即上电状态。 第三个函数choose_address()为设备选择一个地址。后面会用实例来查看效果。 第四个函数hub_port_init()端口初始化主要就是前面所讲的获取设备的描述符。 第五个函数usb_get_status()这个函数是专门为 Hub 准备的不是为当前的这个 Hub而是说当前 Hub 的这个端口上连接的如果又是 Hub那么和连接普通设备就不一样。 第六个函数check_highspeed()不同速度的设备当然待遇不一样。 第七个函数usb_new_device()。寻找驱动程序调用驱动程序的 probe跟踪这个函数就能一直到设备驱动程序的 probe() 函数的调用。 第八个函数hub_power_remaining()电源管理。
usb_alloc_dev
struct usb_device *
usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port1)
{struct usb_device *dev;// ...device_initialize(dev-dev);dev-dev.bus usb_bus_type;dev-dev.type usb_device_type;dev-dev.dma_mask bus-controller-dma_mask;dev-state USB_STATE_ATTACHED;INIT_LIST_HEAD(dev-ep0.urb_list);dev-ep0.desc.bLength USB_DT_ENDPOINT_SIZE;dev-ep0.desc.bDescriptorType USB_DT_ENDPOINT;/* ep0 maxpacket comes later, from device descriptor */dev-ep_in[0] dev-ep_out[0] dev-ep0;// ...dev-portnum port1;dev-bus bus;dev-parent parent;INIT_LIST_HEAD(dev-filelist);#ifdef CONFIG_PMmutex_init(dev-pm_mutex);INIT_DELAYED_WORK(dev-autosuspend, usb_autosuspend_work);dev-autosuspend_delay usb_autosuspend_delay * HZ;
#endifreturn dev;
}usb_set_device_state
void usb_set_device_state(struct usb_device *udev,enum usb_device_state new_state)
{unsigned long flags;spin_lock_irqsave(device_state_lock, flags);if (udev-state USB_STATE_NOTATTACHED); /* do nothing */else if (new_state ! USB_STATE_NOTATTACHED) {/* root hub wakeup capabilities are managed out-of-band* and may involve silicon errata ... ignore them here.*/if (udev-parent) {if (udev-state USB_STATE_SUSPENDED|| new_state USB_STATE_SUSPENDED); /* No change to wakeup settings */else if (new_state USB_STATE_CONFIGURED)device_init_wakeup(udev-dev,(udev-actconfig-desc.bmAttributes USB_CONFIG_ATT_WAKEUP));elsedevice_init_wakeup(udev-dev, 0);}udev-state new_state;} elserecursively_mark_NOTATTACHED(udev);spin_unlock_irqrestore(device_state_lock, flags);
}hub_port_init
static int
hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,int retry_counter)
{// .../* Reset the device; full speed may morph to high speed */retval hub_port_reset(hub, port1, udev, delay);// ...for (i 0; i GET_DESCRIPTOR_TRIES; (i, msleep(100))) {if (USE_NEW_SCHEME(retry_counter)) {struct usb_device_descriptor *buf;int r 0;#define GET_DESCRIPTOR_BUFSIZE 64buf kmalloc(GET_DESCRIPTOR_BUFSIZE, GFP_NOIO);// ...for (j 0; j 3; j) {buf-bMaxPacketSize0 0;r usb_control_msg(udev, usb_rcvaddr0pipe(),USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,USB_DT_DEVICE 8, 0,buf, GET_DESCRIPTOR_BUFSIZE,USB_CTRL_GET_TIMEOUT);// ...}udev-descriptor.bMaxPacketSize0 buf-bMaxPacketSize0;kfree(buf);retval hub_port_reset(hub, port1, udev, delay);// ...}for (j 0; j SET_ADDRESS_TRIES; j) {retval hub_set_address(udev);if (retval 0)break;msleep(200);}// ...retval usb_get_device_descriptor(udev, 8);// ...
}usb_new_device
int usb_new_device(struct usb_device *udev)
{// ...usb_detect_quirks(udev);err usb_get_configuration(udev);// .../* read the standard strings and cache them if present */udev-product usb_cache_string(udev, udev-descriptor.iProduct);udev-manufacturer usb_cache_string(udev,udev-descriptor.iManufacturer);udev-serial usb_cache_string(udev, udev-descriptor.iSerialNumber);// .../* export the usbdev device-node for libusb */udev-dev.devt MKDEV(USB_DEVICE_MAJOR,(((udev-bus-busnum-1) * 128) (udev-devnum-1)));// ...err device_add(udev-dev);// ...if (udev-parent)usb_autoresume_device(udev-parent);// ...
}☆
