介绍USB设备结构体和设备描述符结构体。
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1. USB设备结构体
usb_device位于/linux/include/usb.h
/**
* struct usb_device - kernel's representation of a USB device
* @devnum: device number; address on a USB bus
* @devpath: device ID string for use in messages (e.g., /port/...)
* @route: tree topology hex string for use with xHCI
* @state: device state: configured, not attached, etc.
* @speed: device speed: high/full/low (or error)
* @tt: Transaction Translator info; used with low/full speed dev, highspeed hub
* @ttport: device port on that tt hub
* @toggle: one bit for each endpoint, with ([0] = IN, [1] = OUT) endpoints
* @parent: our hub, unless we're the root
* @bus: bus we're part of
* @ep0: endpoint 0 data (default control pipe)
* @dev: generic device interface
* @descriptor: USB device descriptor
* @bos: USB device BOS descriptor set
* @config: all of the device's configs
* @actconfig: the active configuration
* @ep_in: array of IN endpoints
* @ep_out: array of OUT endpoints
* @rawdescriptors: raw descriptors for each config
* @bus_mA: Current available from the bus
* @portnum: parent port number (origin 1)
* @level: number of USB hub ancestors
* @can_submit: URBs may be submitted
* @persist_enabled: USB_PERSIST enabled for this device
* @have_langid: whether string_langid is valid
* @authorized: policy has said we can use it;
* (user space) policy determines if we authorize this device to be
* used or not. By default, wired USB devices are authorized.
* WUSB devices are not, until we authorize them from user space.
* FIXME -- complete doc
* @authenticated: Crypto authentication passed
* @wusb: device is Wireless USB
* @lpm_capable: device supports LPM
* @usb2_hw_lpm_capable: device can perform USB2 hardware LPM
* @usb2_hw_lpm_besl_capable: device can perform USB2 hardware BESL LPM
* @usb2_hw_lpm_enabled: USB2 hardware LPM is enabled
* @usb2_hw_lpm_allowed: Userspace allows USB 2.0 LPM to be enabled
* @usb3_lpm_u1_enabled: USB3 hardware U1 LPM enabled
* @usb3_lpm_u2_enabled: USB3 hardware U2 LPM enabled
* @string_langid: language ID for strings
* @product: iProduct string, if present (static)
* @manufacturer: iManufacturer string, if present (static)
* @serial: iSerialNumber string, if present (static)
* @filelist: usbfs files that are open to this device
* @maxchild: number of ports if hub
* @quirks: quirks of the whole device
* @urbnum: number of URBs submitted for the whole device
* @active_duration: total time device is not suspended
* @connect_time: time device was first connected
* @do_remote_wakeup: remote wakeup should be enabled
* @reset_resume: needs reset instead of resume
* @port_is_suspended: the upstream port is suspended (L2 or U3)
* @wusb_dev: if this is a Wireless USB device, link to the WUSB
* specific data for the device.
* @slot_id: Slot ID assigned by xHCI
* @removable: Device can be physically removed from this port
* @l1_params: best effor service latency for USB2 L1 LPM state, and L1 timeout.
* @u1_params: exit latencies for USB3 U1 LPM state, and hub-initiated timeout.
* @u2_params: exit latencies for USB3 U2 LPM state, and hub-initiated timeout.
* @lpm_disable_count: Ref count used by usb_disable_lpm() and usb_enable_lpm()
* to keep track of the number of functions that require USB 3.0 Link Power
* Management to be disabled for this usb_device. This count should only
* be manipulated by those functions, with the bandwidth_mutex is held.
*
* Notes:
* Usbcore drivers should not set usbdev->state directly. Instead use
* usb_set_device_state().
*/
struct usb_device {
int devnum; //设备号，还记得上一篇USB命名"设备号-端口号：配置.接口"命名方式，每插入一个新设备，USBCore会为其设置一个设备号
char devpath[16]; //该设备在SysFS中的路径，一般为"/sys/devices/pci0000:00/0000:00:12.2/_usb_1"
u32 route;
enum usb_device_state state; //该设备的状态，如刚插上时为Attached
enum usb_device_speed speed; //速度级别 high full low
struct usb_tt *tt; //我们知道高速USB之前还存在全速和低速USB,那么高速USB设备怎么兼容其他
int ttport; //低速设备，通过使用TT(Transaction Translator)--高速USB中的转换电路
unsigned int toggle[2]; //对于中断传输、批量传输、和控制传输，传输数据时，需要DATA0和DATA1交
//替进行，toggle就是标识0端点的IN 和 OUT的DATAx的状态
struct usb_device *parent; //父hub,如果是roothub，就是NULL
struct usb_bus *bus; //设备所在的总线
struct usb_host_endpoint ep0; //端点0被特殊对待，在结构体中静态存在
struct device dev; //嵌入到usb_device中的device
struct usb_device_descriptor descriptor; //设备描述符，描述该设备信息，后面会分析
struct usb_host_bos *bos;
struct usb_host_config *config; //所有的配置信息列表
struct usb_host_config *actconfig; //当前活跃的信息
struct usb_host_endpoint *ep_in[16]; //该设备的输入端点
struct usb_host_endpoint *ep_out[16]; //输出端点
char **rawdescriptors;
unsigned short bus_mA; //能够从总线得到的电流值
u8 portnum;
u8 level;
unsigned can_submit:1;
unsigned persist_enabled:1;
unsigned have_langid:1;
unsigned authorized:1;
unsigned authenticated:1;
unsigned wusb:1;
unsigned lpm_capable:1;
unsigned usb2_hw_lpm_capable:1;
unsigned usb2_hw_lpm_besl_capable:1;
unsigned usb2_hw_lpm_enabled:1;
unsigned usb2_hw_lpm_allowed:1;
unsigned usb3_lpm_u1_enabled:1;
unsigned usb3_lpm_u2_enabled:1;
int string_langid;
/* static strings from the device */
char *product;
char *manufacturer;
char *serial;
struct list_head filelist;
int maxchild;
u32 quirks;
atomic_t urbnum;
unsigned long active_duration;
#ifdef CONFIG_PM
unsigned long connect_time;
unsigned do_remote_wakeup:1;
unsigned reset_resume:1;
unsigned port_is_suspended:1;
#endif
struct wusb_dev *wusb_dev;
int slot_id;
enum usb_device_removable removable;
struct usb2_lpm_parameters l1_params;
struct usb3_lpm_parameters u1_params;
struct usb3_lpm_parameters u2_params;
unsigned lpm_disable_count;
};
#define to_usb_device(d) container_of(d, struct usb_device, dev)2 USB设备描述符结构体
usb_device_descriptor位于“
/* USB_DT_DEVICE: Device descriptor */
struct usb_device_descriptor {
__u8 bLength; //该设备描述符的长度
__u8 bDescriptorType; // USB_DT_DEVICE = 0x01
__le16 bcdUSB; //版本号
__u8 bDeviceClass; //
__u8 bDeviceSubClass;
__u8 bDeviceProtocol;
__u8 bMaxPacketSize0; //端点0一次可以处理的最大字节数
__le16 idVendor; //厂商号
__le16 idProduct; //产品号
__le16 bcdDevice; //版本号
__u8 iManufacturer; //分别对应上面的索引值 index
__u8 iProduct;
__u8 iSerialNumber;
__u8 bNumConfigurations; //设备在当前速度级别下支持的配置数量
} __attribute__ ((packed));