usb请求块以及提交方式
URB结构体
struct urb {
/* private: usb core and host controller only fields in the urb */
struct kref kref; /* reference count of the URB */
void *hcpriv; /* private data for host controller */
atomic_t use_count; /* concurrent submissions counter */
atomic_t reject; /* submissions will fail */
int unlinked; /* unlink error code */
/* public: documented fields in the urb that can be used by drivers */
struct list_head urb_list; /* list head for use by the urb's
* current owner */
struct list_head anchor_list; /* the URB may be anchored */
struct usb_anchor *anchor;
struct usb_device *dev; /* (in) pointer to associated device */
struct usb_host_endpoint *ep; /* (internal) pointer to endpoint */
unsigned int pipe; /* (in) pipe information */
unsigned int stream_id; /* (in) stream ID */
int status; /* (return) non-ISO status */
unsigned int transfer_flags; /* (in) URB_SHORT_NOT_OK | ...*/
void *transfer_buffer; /* (in) associated data buffer */
dma_addr_t transfer_dma; /* (in) dma addr for transfer_buffer */
struct scatterlist *sg; /* (in) scatter gather buffer list */
int num_mapped_sgs; /* (internal) mapped sg entries */
int num_sgs; /* (in) number of entries in the sg list */
u32 transfer_buffer_length; /* (in) data buffer length */
u32 actual_length; /* (return) actual transfer length */
unsigned char *setup_packet; /* (in) setup packet (control only) */
dma_addr_t setup_dma; /* (in) dma addr for setup_packet */
int start_frame; /* (modify) start frame (ISO) */
int number_of_packets; /* (in) number of ISO packets */
int interval; /* (modify) transfer interval
* (INT/ISO) */
int error_count; /* (return) number of ISO errors */
void *context; /* (in) context for completion */
usb_（1）异步提交urb，提交完成后通过usb_fill[control] [int] [bulk]_urb传入的回调函数
_t complete; /* (in) completion routine */
struct usb_iso_packet_descriptor iso_frame_desc[0];
/* (in) ISO ONLY */
};
- pipe:端点需要和主机控制器需要通过pipe进行通信；
unsigned int pipe; /* (in) pipe information */
-
urb是主机控制器发给设备的，因此需要将设备的pipe告诉主机控制器。
-
transfer_buffer：in端点时，存放设备发给主机控制器的数据；out端点时，存放主机控制器发给设备的数据。
void *transfer_buffer; /* (in) associated data buffer */
- buffder长度；
u32 transfer_buffer_length; /* (in) data buffer length */
- complete:complete是一个回调函数，当通讯接收后，会调用。
usb_complete_t complete; /* (in) completion routine */
每一个urb都是由usb主机控制器发送给usb设备的。
urb使用方式
1.分配urb
struct urb *usb_alloc_urb(int iso_packets,gfp_t mem_flags);
2.初始化urb
usb控制传输：void usb_fill_control_urb();
usb中断传输：void usb_fill_int_urb();
usb批量传输：void usb_fill_bulk();
以上函数不适用于等时传输：
3.提交urb（提交给主控制器，由主控制器发送给usb设备）
（1）异步提交urb，提交完成后通过usb_fill[control] [int] [bulk]_urb传入的回调函数
int usb_submit_urb(struct urb *urb,gfp_t mem_flags);
该函数只管发出去，不管是否发送成功。
(2)同步提交urb
int usb_fill[control] [int] [bulk]_msg（
struct usb_device *usb_dev,
unsigned int pipe,
void *data,
int len,
int *actual_length,
int timeout）;
同步提交会一直等待urb提交成功；
usb 驱动数据结构
struct usb_device {
int devnum;
char devpath[16];
u32 route;
enum usb_device_state state;
enum usb_device_speed speed;
unsigned int rx_lanes;
unsigned int tx_lanes;
struct usb_tt *tt;
int ttport;
unsigned int toggle[2];
struct usb_device *parent;
struct usb_bus *bus;
struct usb_host_endpoint ep0;
struct device dev;
struct usb_device_descriptor descriptor;
struct usb_host_bos *bos;
struct usb_host_config *config;
struct usb_host_config *actconfig;
struct usb_host_endpoint *ep_in[16];
struct usb_host_endpoint *ep_out[16];
char **rawdescriptors;
unsigned short bus_mA;
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;
u16 hub_delay;
};
struct usb_device描述一个usb设备
管道
每个断点通过管道和usb主控制器连接，管道包括以下几个部分：
1.端点地址
2.数据传输方向（IN或OUT）
3.数据传输模式
usb_[rcv][snd][ctrl][int][bulk][isoc]pipe(struct usb_device *usb_dev,_u8 endpointAddress);
分别表示接收，发送，控制，中断，批量，等时管道；
得到一个pipe，主机得到这个pipe，就知道跟谁去通讯了；
