USB驅動框架(二)

    前面簡單聊了一下USB驅動的整體框架《USB驅動框架(一)》，接下來看一下主機控制器驅動框架。

網絡圖片

USB核心(USBD)是整個USB驅動的核心部分，一方面USBD對從USB主機控制器接收到的數據進行處理，然後傳遞給上層的設備端驅動；同時也接收來自上層的非USB格式數據流，進行相應的數據處理後傳遞給USB主機控制器驅動。所以它起了一個承上啟下的作用。

//include/linux/usb/hcd.hstruct usb_hcd {
  struct usb_bus    self;    /* hcd是一個總線 */  struct kref    kref;    /* 引用計數 */
  const char    *product_desc;  /* product/vendor字符創 */  int      speed;    /* roothub速率*/  char      irq_descr[24];  /* driver + bus # */
  struct timer_list  rh_timer;  /* 驅動root-hub輪詢 */  struct urb    *status_urb;  /* 當前狀態urb */#ifdef CONFIG_PM  struct work_struct  wakeup_work;  /* 遠程喚醒 */#endif
    //操作主機控制器的回調函數  const struct hc_driver  *driver;
    //OTG或外掛USB控制器  struct usb_phy    *usb_phy;  struct usb_phy_roothub  *phy_roothub;
  //狀態標誌  unsigned long    flags;   //省略宏定義....
    //HCD註冊或移除時設置的標誌  unsigned    rh_registered:1;/* is root hub registered? */  unsigned    rh_pollable:1;  /* may we poll the root hub? */  unsigned    msix_enabled:1;  /* driver has MSI-X enabled? */  unsigned    msi_enabled:1;  /* driver has MSI enabled? */
  unsigned    skip_phy_initialization:1;    //省略..
    //中斷號及內存資源  unsigned int    irq;    /* irq allocated */  void __iomem    *regs;    /* device memory/io */  resource_size_t    rsrc_start;  /* memory/io resource start */  resource_size_t    rsrc_len;  /* memory/io resource length */  unsigned    power_budget;  /* in mA, 0 = no limit */
  struct giveback_urb_bh  high_prio_bh;  struct giveback_urb_bh  low_prio_bh;
   //互斥鎖  struct mutex    *address0_mutex;  struct mutex    *bandwidth_mutex;  struct usb_hcd    *shared_hcd;  struct usb_hcd    *primary_hcd;
   //緩衝區池#define HCD_BUFFER_POOLS  4  struct dma_pool    *pool[HCD_BUFFER_POOLS];
  int      state;   //省略宏定義....
   //HCD私有數據存儲在該結構體的末尾  unsigned long hcd_priv[0]      __attribute__ ((aligned(sizeof(s64))));};
//include/linux/usb/hcd.hstruct hc_driver {  const char  *description;  /* "ehci-hcd" etc */  const char  *product_desc;  /* product/vendor 字符串 */  size_t    hcd_priv_size;  /* 私有數據大小 */
  /* 中斷處理函數 */  irqreturn_t  (*irq) (struct usb_hcd *hcd);
  int  flags;#define  HCD_MEMORY  0x0001    /* HC regs use memory (else I/O) */#define  HCD_LOCAL_MEM  0x0002    /* HC needs local memory */#define  HCD_SHARED  0x0004    /* Two (or more) usb_hcds share HW */#define  HCD_USB11  0x0010    /* USB 1.1 */#define  HCD_USB2  0x0020    /* USB 2.0 */#define  HCD_USB25  0x0030    /* Wireless USB 1.0 (USB 2.5)*/#define  HCD_USB3  0x0040    /* USB 3.0 */#define  HCD_USB31  0x0050    /* USB 3.1 */#define  HCD_USB32  0x0060    /* USB 3.2 */#define  HCD_MASK  0x0070#define  HCD_BH    0x0100    /* URB complete in BH context */
   //初始化HCD和roothub時調用  int  (*reset) (struct usb_hcd *hcd);  int  (*start) (struct usb_hcd *hcd);

   //掛起hub時調用  int  (*pci_suspend)(struct usb_hcd *hcd, bool do_wakeup);
   //恢復hub調用  int  (*pci_resume)(struct usb_hcd *hcd, bool hibernated);
   //停止HCD  void  (*stop) (struct usb_hcd *hcd);
  //關閉HCD  void  (*shutdown) (struct usb_hcd *hcd);
  //返回當前幀號  int  (*get_frame_number) (struct usb_hcd *hcd);
    //管理IO請求，設備狀態  int  (*urb_enqueue)(struct usb_hcd *hcd,        struct urb *urb, gfp_t mem_flags);  int  (*urb_dequeue)(struct usb_hcd *hcd,        struct urb *urb, int status);

    //重寫HCD默認的DMA映射和取消映射，非必須情況下，不要實現  int  (*map_urb_for_dma)(struct usb_hcd *hcd, struct urb *urb,           gfp_t mem_flags);  void    (*unmap_urb_for_dma)(struct usb_hcd *hcd, struct urb *urb);
   //硬體同步，釋放urb出列無法釋放的端點資源  void  (*endpoint_disable)(struct usb_hcd *hcd,      struct usb_host_endpoint *ep);
    //復位端點  void  (*endpoint_reset)(struct usb_hcd *hcd,      struct usb_host_endpoint *ep);
  /* root hub支持 */  int  (*hub_status_data) (struct usb_hcd *hcd, char *buf);  int  (*hub_control) (struct usb_hcd *hcd,        u16 typeReq, u16 wValue, u16 wIndex,        char *buf, u16 wLength);  int  (*bus_suspend)(struct usb_hcd *);  int  (*bus_resume)(struct usb_hcd *);  int  (*start_port_reset)(struct usb_hcd *, unsigned port_num);  unsigned long  (*get_resuming_ports)(struct usb_hcd *);
   //將高速埠切換為全速  void  (*relinquish_port)(struct usb_hcd *, int);    /* has a port been handed over to a companion? */  int  (*port_handed_over)(struct usb_hcd *, int);
  /* CLEAR_TT_BUFFER完成回調 */  void  (*clear_tt_buffer_complete)(struct usb_hcd *,        struct usb_host_endpoint *);
  /* xHCI專用函數 */    //使用usb_alloc_dev分配HC設備結構體時回調  int  (*alloc_dev)(struct usb_hcd *, struct usb_device *);   //使用usb_disconnect釋放HC設備結構體時回調  void  (*free_dev)(struct usb_hcd *, struct usb_device *);  //更改一組批量端點以支持多個流id  int  (*alloc_streams)(struct usb_hcd *hcd, struct usb_device *udev,    struct usb_host_endpoint **eps, unsigned int num_eps,    unsigned int num_streams, gfp_t mem_flags);    //將一組批量端點恢復為不使用流id  int  (*free_streams)(struct usb_hcd *hcd, struct usb_device *udev,    struct usb_host_endpoint **eps, unsigned int num_eps,    gfp_t mem_flags);

  /* 帶寬計算函數 */  //添加一個端點  int  (*add_endpoint)(struct usb_hcd *, struct usb_device *,        struct usb_host_endpoint *);   //刪除端點  int  (*drop_endpoint)(struct usb_hcd *, struct usb_device *,         struct usb_host_endpoint *);   //檢查一個新的硬體配置，必須在設置配置或設置接口請求前調用  int  (*check_bandwidth)(struct usb_hcd *, struct usb_device *);  //重置設備調度到最後已知的良好調度  void  (*reset_bandwidth)(struct usb_hcd *, struct usb_device *);  //返回設備地址  int  (*address_device)(struct usb_hcd *, struct usb_device *udev);  //準備硬體向設備發送命令  int  (*enable_device)(struct usb_hcd *, struct usb_device *udev);
   //hub描述符獲取到後通知HCD  int  (*update_hub_device)(struct usb_hcd *, struct usb_device *hdev,      struct usb_tt *tt, gfp_t mem_flags);  int  (*reset_device)(struct usb_hcd *, struct usb_device *);
   //設備的地址設置之後通知HCD  int  (*update_device)(struct usb_hcd *, struct usb_device *);  int  (*set_usb2_hw_lpm)(struct usb_hcd *, struct usb_device *, int);
  /* USB 3.0 線電源管理 */  int  (*enable_usb3_lpm_timeout)(struct usb_hcd *,      struct usb_device *, enum usb3_link_state state);  int  (*disable_usb3_lpm_timeout)(struct usb_hcd *,      struct usb_device *, enum usb3_link_state state);  int  (*find_raw_port_number)(struct usb_hcd *, int);  int  (*port_power)(struct usb_hcd *hcd, int portnum, bool enable);};
調用usb_submit_urb()提交一個USB請求之後，該函數調用usb_hcd_submit_urb() , 並最終調用usb_hcd的driver成員(hc_driver類型)的urb_enqueue()函數。
//drivers/usb/host/echi.hstruct ehci_hcd {      /* one per controller */  /* 時序支持 */  enum ehci_hrtimer_event  next_hrtimer_event;  unsigned    enabled_hrtimer_events;  ktime_t      hr_timeouts[EHCI_HRTIMER_NUM_EVENTS];  struct hrtimer    hrtimer;
  int      PSS_poll_count;  int      ASS_poll_count;  int      died_poll_count;
  /* glue to PCI and HCD framework */  struct ehci_caps __iomem *caps;  struct ehci_regs __iomem *regs;  struct ehci_dbg_port __iomem *debug;
  __u32      hcs_params;  /* 緩存寄存器拷貝 */  spinlock_t    lock;  enum ehci_rh_state  rh_state;
  /* 普通schedule支持*/  bool      scanning:1;  bool      need_rescan:1;  bool      intr_unlinking:1;  bool      iaa_in_progress:1;  bool      async_unlinking:1;  bool      shutdown:1;  struct ehci_qh    *qh_scan_next;
  /* 異步schedule支持 */  struct ehci_qh    *async;  struct ehci_qh    *dummy;    /* For AMD quirk use */  struct list_head  async_unlink;  struct list_head  async_idle;  unsigned    async_unlink_cycle;  unsigned    async_count;  /* async activity count */  __hc32      old_current;  /* Test for QH becoming */  __hc32      old_token;  /*  inactive during unlink */
  /* 周期性schedule支持 */#define  DEFAULT_I_TDPS    1024    /* some HCs can do less */  unsigned    periodic_size;  __hc32      *periodic;  /* hw periodic table */  dma_addr_t    periodic_dma;  struct list_head  intr_qh_list;  unsigned    i_thresh;  /* uframes HC might cache */
  union ehci_shadow  *pshadow;  /* mirror hw periodic table */  struct list_head  intr_unlink_wait;  struct list_head  intr_unlink;  unsigned    intr_unlink_wait_cycle;  unsigned    intr_unlink_cycle;  unsigned    now_frame;  /* frame from HC hardware */  unsigned    last_iso_frame;  /* last frame scanned for iso */  unsigned    intr_count;  /* intr activity count */  unsigned    isoc_count;  /* isoc activity count */  unsigned    periodic_count;  /* periodic activity count */  unsigned    uframe_periodic_max; /* max periodic time per uframe */  //省略  /* 每個root hub口 */  unsigned long    reset_done[EHCI_MAX_ROOT_PORTS];
  /* bit vectors (每位代表一個port) */  unsigned long    bus_suspended;    /* 在總線開始時已經被掛起的port */  unsigned long    companion_ports;  /* which ports are      dedicated to the companion controller */  unsigned long    owned_ports;    /* which ports are      owned by the companion during a bus suspend */  unsigned long    port_c_suspend;    /* which ports have      the change-suspend feature turned on */  unsigned long    suspended_ports;  /* 被掛起的port */  unsigned long    resuming_ports;    /* 恢復的port */
  /* 每個主機控制器內存池 */  struct dma_pool    *qh_pool;  /* qh per active urb */  struct dma_pool    *qtd_pool;  /* one or more per qh */  struct dma_pool    *itd_pool;  /* itd per iso urb */  struct dma_pool    *sitd_pool;  /* sitd per split iso urb */
  unsigned    random_frame;  unsigned long    next_statechange;  ktime_t      last_periodic_enable;  u32      command;
//省略  __hc32      *ohci_hcctrl_reg;  unsigned    has_hostpc:1;  unsigned    has_tdi_phy_lpm:1;  unsigned    has_ppcd:1; /* support per-port change bits */  u8      sbrn;    /* packed release number */
  /* irq statistics */#ifdef EHCI_STATS  struct ehci_stats  stats;#  define INCR(x) ((x)++)#else#  define INCR(x) do {} while (0)#endif
  /* debug文件 */#ifdef CONFIG_DYNAMIC_DEBUG  struct dentry    *debug_dir;#endif
  /* 帶寬使用 */#define EHCI_BANDWIDTH_SIZE  64#define EHCI_BANDWIDTH_FRAMES  (EHCI_BANDWIDTH_SIZE >> 3)  u8      bandwidth[EHCI_BANDWIDTH_SIZE];            /* us allocated per uframe */  u8      tt_budget[EHCI_BANDWIDTH_SIZE];            /* us budgeted per uframe */  struct list_head  tt_list;
  //平臺數據  unsigned long    priv[0] __aligned(sizeof(s64));};
ECHI HCD驅動屬於HCD驅動的實例，用ehci_hcd結構體來表示，它通常會作為usb_hcd結構體的私有數據(hcd_priv) 。


//創建和初始化一個HCD結構體struct usb_hcd *usb_create_hcd(const struct hc_driver *driver,    struct device *dev, const char *bus_name)
//註冊HCD結構體  int usb_add_hcd(struct usb_hcd *hcd,    unsigned int irqnum, unsigned long irqflags)//關閉HCD，斷開roothub連接    void usb_remove_hcd(struct usb_hcd *hcd)  
/**********************EHCI********************************///初始化EHCI主機控制器static int ehci_init(struct usb_hcd *hcd)//開啟EHCI主機控制器static int ehci_run (struct usb_hcd *hcd)//停止EHCI主機控制器static void ehci_stop (struct usb_hcd *hcd)//復位EHCI主機控制器int ehci_reset(struct ehci_hcd *ehci)//設置EHCI主機控制器int ehci_setup(struct usb_hcd *hcd)//usb_hcd轉echi_hcd,內部實現就是從獲取usb_hcd的私有數據static inline struct ehci_hcd *hcd_to_ehci(struct usb_hcd *hcd)//echi_hcd轉usb_hcdstatic inline struct usb_hcd *ehci_to_hcd(struct ehci_hcd *ehci)//EHCI驅動初始化void ehci_init_driver(struct hc_driver *drv,    const struct ehci_driver_overrides *over)
/***********************XHCI**********************************///XHCI驅動初始化void xhci_init_driver(struct hc_driver *drv,          const struct xhci_driver_overrides *over)  
drivers/usb/host/ehci-hcd.c 中實現了絕大多數EHCI主機驅動的工作，具體的驅動只要簡單調用ehci_init_driver()即可。看一下該函數具體實現：
//drivers/usb/host/ehci-hcd.cvoid ehci_init_driver(struct hc_driver *drv,    const struct ehci_driver_overrides *over){     //拷貝通用hc_driver到drv，並重寫部分函數  *drv = ehci_hc_driver;
  if (over) {    drv->hcd_priv_size += over->extra_priv_size;    if (over->reset)      drv->reset = over->reset;    if (over->port_power)      drv->port_power = over->port_power;  }}
上面的函數就是初始化hc_driver, 這個函數會把通用的hc_driver實例ehci_hc_driver複製給每個具體底層驅動的實例，而第二個參數是重寫hc_driver的reset()、 port_power()兩個函數，另外可以填充一些額外的私有數據。
//ehci-hcd.c中實現的通用hc_driverstatic const struct hc_driver ehci_hc_driver = {  .description =    hcd_name,  .product_desc =    "EHCI Host Controller",  .hcd_priv_size =  sizeof(struct ehci_hcd),
  /*   * generic hardware linkage   */  .irq =      ehci_irq,  .flags =    HCD_MEMORY | HCD_USB2 | HCD_BH,
  /*   * basic lifecycle operations   */  .reset =    ehci_setup,  .start =    ehci_run,  .stop =      ehci_stop,  .shutdown =    ehci_shutdown,
  /*   * managing i/o requests and associated device resources   */  .urb_enqueue =    ehci_urb_enqueue,  .urb_dequeue =    ehci_urb_dequeue,  .endpoint_disable =  ehci_endpoint_disable,  .endpoint_reset =  ehci_endpoint_reset,  .clear_tt_buffer_complete =  ehci_clear_tt_buffer_complete,
  /*   * scheduling support   */  .get_frame_number =  ehci_get_frame,
  /*   * root hub support   */  .hub_status_data =  ehci_hub_status_data,  .hub_control =    ehci_hub_control,  .bus_suspend =    ehci_bus_suspend,  .bus_resume =    ehci_bus_resume,  .relinquish_port =  ehci_relinquish_port,  .port_handed_over =  ehci_port_handed_over,  .get_resuming_ports =  ehci_get_resuming_ports,
  /*   * device support   */  .free_dev =    ehci_remove_device,};
上面是Linux已經實現好的通用ehci接口操作函數，基本都是通用的，所以不需要自己再實現。
xhci主機控制器的實現方式和ehci基本一樣，在/drivers/usb/host/xhci.c中實現XHCI主機驅動的工作。具體的驅動只要簡單調用xhci_init_driver()即可。



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