USB 结构体

USB 结构体 struct usb_device_id来自include/linux/mod_devicetable.h struct usb_device_id { 98 /* which fields to match against? */ 99 __u16 match_flags; 100 101 /* Used for product specific matches; range is inclusive */ 102 __u16 idVendor; 103 __u16 idProduct; 104 __u16 bcdDevice_lo; 105 __u16 bcdDevice_hi; 106 107 /* Used for device class matches */ 108 __u8 bDeviceClass; 109 __u8 bDeviceSubClass; 110 __u8 bDeviceProtocol; 111 112 /* Used for interface class matches */ 113 __u8 bInterfaceClass; 114 __u8 bInterfaceSubClass; 115 __u8 bInterfaceProtocol; 116 117 /* not matched against */ 118 kernel_ulong_t driver_info; 119 }; 上节我们注意到id_index=id-storage_usb_ids,id我们知道,storage_probe函数的两个形 参之一,而 storage_usb_ids,不是别人,正是我们曾经赋给usb_storage_driver的成员id_table的值. 忘记了 id_table的可以回去看.它实际上就是一张格,告诉全世界我这个driver支持怎样的一些 设 备.storage_usb_ids同样来自drivers/usb/storage/usb.c中, 111 /* The entries in this table, except for final ones here 112 * (USB_MASS_STORAGE_CLASS and the empty entry), correspond, 113 * line for line with the entries of us_unsuaul_dev_list[]. 114 */ 115 116 #define UNUSUAL_DEV(id_vendor, id_product, bcdDeviceMin, bcdDeviceMax, \ 117 vendorName, productName,useProtocol, useTransport, \ 118 initFunction, flags) \ 119 { USB_DEVICE_VER(id_vendor, id_product, bcdDeviceMin,bcdDeviceMax) } 120 121 static struct usb_device_id storage_usb_ids [] = { 122 123 # include "unusual_devs.h" 124 #undef UNUSUAL_DEV 125 /* Control/Bulk transport for all SubClass values */ 126 { USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, US_SC_RBC, US_PR_CB) }, 127 { USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, US_SC_8020, US_PR_CB) }, USB_INTERFACE_INFO这个咚咚,很显 然这是一个宏,来自include/linux/usb.h, 482 #define USB_INTERFACE_INFO(cl,sc,pr) \ 483 .match_flags = USB_DEVICE_ID_MATCH_INT_INFO, .bInterfaceClass = (cl), .bInterfaceSubClass = (sc), .bInterfaceProtocol = (pr) 每一个USB_INTERFACE_INFO就是构造一个struct usb_device_id的结构体变量,回顾一下我 们之前 给出的struct usb_device_id的定义,这里实际上就是为其中的四个元素赋了值,它们是 match_flags,bInterfaceClass,bInterfaceSubClass,bInterfaceProtocol. match_flag,它又是表示什么意思?USB_INTERFACE_INFO这个宏貌似把所有的设 备的match_flag都给设成了USB_DEVICE_ID_MATCH_INT_INFO,这是为啥?这个宏来自 include/linux/usb.h, 435 #define USB_DEVICE_ID_MATCH_INT_INFO \ 436 (USB_DEVICE_ID_MATCH_INT_CLASS | USB_DEVICE_ID_MATCH_INT_SUBCLASS | USB_DEVICE_ID_MATCH_INT_PROTOCOL) match_flag这个咚咚是给usb core去用的,usb core负责给设备寻找适合她的driver,负责 给driver 寻找适合他的device,它所比较的就是struct usb_device_id的变量,而struct usb_device_id结构体 中有许多成员,那么是不是一定要把每一个成员都给比较一下呢,其实没有必要那么细,差不 多就行了,比如 咱们这里,就是告诉usb core,你只要比较 bInterfaceClass,bInterfaceSubClass,bInterfaceProtocol 即可.include/linux/mod_devicetable.h中针对struct usb_device_id中的每一个要比较 的项定义了 一个宏: 32 121 /* Some useful macros to use to create struct usb_device_id */ 122 #define USB_DEVICE_ID_MATCH_VENDOR 0x0001 123 #define USB_DEVICE_ID_MATCH_PRODUCT 0x0002 124 #define USB_DEVICE_ID_MATCH_DEV_LO 0x0004 125 #define USB_DEVICE_ID_MATCH_DEV_HI 0x0008 126 #define USB_DEVICE_ID_MATCH_DEV_CLASS 0x0010 127 #define USB_DEVICE_ID_MATCH_DEV_SUBCLASS 0x0020 128 #define USB_DEVICE_ID_MATCH_DEV_PROTOCOL 0x0040 129 #define USB_DEVICE_ID_MATCH_INT_CLASS 0x0080 130 #define USB_DEVICE_ID_MATCH_INT_SUBCLASS 0x0100 131 #define USB_DEVICE_ID_MATCH_INT_PROTOCOL 0x0200 回去对比一下struct usb_device_id就知道这些宏是什么意思了. 472行, struct us_unusual_dev,这个结构体是第一次出现,她定义于 drivers/usb/storage/usb.h中, 55 /* 56 * Unusual device list definitions 57 */ 58 59 struct us_unusual_dev { 60 const char* vendorName; 61 const char* productName; 62 __u8 useProtocol; 63 __u8 useTransport; 64 int (*initFunction)(struct us_data *); 65 unsigned int flags; 66 }; us_unusal_dev_list是一个数组,定义于drivers/usb/storage/usb.c: static struct us_unusual_dev us_unusual_dev_list[] = { #undef UNUSUAL_DEV 169 #define UNUSUAL_DEV(idVendor, idProduct, bcdDeviceMin, bcdDeviceMax, \ 170 vendor_name, product_name, use_protocol, use_transport, \ 171 init_function, Flags) \ 172 { \ 173 .vendorName = vendor_name, \ 174 .productName = product_name, \ 175 .useProtocol = use_protocol, \ 176 .useTransport = use_transport, \ 177 .initFunction = init_function, \ 178 .flags = Flags, \ 179 } 180 182 # include "unusual_devs.h" 183 # undef UNUSUAL_DEV 184 /* Control/Bulk transport for all SubClass values */ 185 { .useProtocol = US_SC_RBC, 186 .useTransport = US_PR_CB}, 187 { .useProtocol = US_SC_8020, 188 .useTransport = US_PR_CB}, . . . struct usb_interface.它定义于 include/linux/usb.h: struct usb_interface { 116 /* array of alternate settings for this interface, 117 * stored in no particular order */ 118 struct usb_host_interface *altsetting; 119 120 struct usb_host_interface *cur_altsetting; /* the currently 121 * active alternate setting */ 122 unsigned num_altsetting; /* number of alternate settings */ 123 124 int minor; /* minor number this interface is bound to */ 125 enum usb_interface_condition condition; /* state of binding */ 126 struct device dev; /* interface specific device info */ 127 struct class_device *class_dev; 128 }; 129 #define to_usb_interface(d) container_of(d, struct usb_interface, dev) 130 #define interface_to_usbdev(intf) \ 131 container_of(intf->dev.parent, struct usb_device, dev) 于include/linux/usb.h: struct usb_host_interface { 53 struct usb_interface_descriptor desc; 54 55 /* array of desc.bNumEndpoint endpoints associated with this 56 * interface setting. these will be in no particular order. 57 */ 58 struct usb_host_endpoint *endpoint; 59 60 unsigned char *extra; /* Extra descriptors */ 61 int extralen; 35 62 }; include/linux/usb_ch9.h.(这里取名为"ch9"是因为这个文件很多东西对应于usb spec 2.0中的第九章,chapter 9.): 242 /* USB_DT_INTERFACE: Interface descriptor */ 243 struct usb_interface_descriptor { 244 __u8 bLength; 245 __u8 bDescriptorType; 246 247 __u8 bInterfaceNumber; 248 __u8 bAlternateSetting; 249 __u8 bNumEndpoints; 250 __u8 bInterfaceClass; 251 __u8 bInterfaceSubClass; 252 __u8 bInterfaceProtocol; 253 __u8 iInterface; 254 } __attribute__ ((packed)); struct usb_host_endpoint的定义,来自include/linux/usb.h: 43 /* host-side wrapper for parsed endpoint descriptors */ 44 struct usb_host_endpoint { 45 struct usb_endpoint_descriptor desc; 46 47 unsigned char *extra; /* Extra descriptors */ 48 int extralen; 49 }; struct usb_endpoint_descriptor的结构体指针.顾名思义,这就是对应endpoint的 描述符的.其定义来自于include/linux/usb_ch9.h: 260 /* USB_DT_ENDPOINT: Endpoint descriptor */ 261 struct usb_endpoint_descriptor { 262 __u8 bLength; 263 __u8 bDescriptorType; 264 265 __u8 bEndpointAddress; 266 __u8 bmAttributes; 267 __u16 wMaxPacketSize; 268 __u8 bInterval; 269 270 // NOTE: these two are _only_ in audio endpoints. 271 // use USB_DT_ENDPOINT*_SIZE in bLength, not sizeof. 272 __u8 bRefresh; 273 __u8 bSynchAddress; 274 } __attribute__ ((packed)); struct usb_endpoint_descriptor,它的成员中, bmAttributes表示属性,总共8位,其中bit1 和bit0共同称为Transfer Type,即传输类型,即00表示控制,01表示等时,10表示批量,11 表示中断.而 719行我们看到, USB_ENDPOINT_XFERTYPE_MASK这个宏定义于include/linux/usb_ch9.h中: 286 #define USB_ENDPOINT_XFERTYPE_MASK 0x03 /* in bmAttributes */ 287 #define USB_ENDPOINT_XFER_CONTROL 0 288 #define USB_ENDPOINT_XFER_ISOC 1 289 #define USB_ENDPOINT_XFER_BULK 2 290 #define USB_ENDPOINT_XFER_INT 3 USB_DIR_IN仍然来自 include/linux/usb_ch9.h * USB directions 57 27 * 28 * This bit flag is used in endpoint descriptors' bEndpointAddress field. 29 * It's also one of three fields in control requests bRequestType. 30 */ 31 #define USB_DIR_OUT 0 /* to device */ 32 #define USB_DIR_IN 0x80 /* to host */ 68页 include/linux/usb.h 779 struct urb 780 { 781 /* private, usb core and host controller only fields in the urb */ 782 struct kref kref; /* reference count of the URB */ 783 spinlock_t lock; /* lock for the URB */ 784 void *hcpriv; /* private data for host controller */ 785 struct list_head urb_list; /* list pointer to all active urbs */ 786 int bandwidth; /* bandwidth for INT/ISO request */ 787 atomic_t use_count; /* concurrent submissions counter */ 788 u8 reject; /* submissions will fail */ 789 790 /* public, documented fields in the urb that can be used by drivers */ 791 struct usb_device *dev; /* (in) pointer to associated device */ 792 unsigned int pipe; /* (in) pipe information */ 793 int status; /* (return) non-ISO status */ 794 unsigned int transfer_flags; /* (in) URB_SHORT_NOT_OK | ...*/ 795 void *transfer_buffer; /* (in) associated data buffer */ 796 dma_addr_t transfer_dma; /* (in) dma addr for transfer_buffer */ 797 int transfer_buffer_length; /* (in) data buffer length */ 798 int actual_length; /* (return) actual transfer length */ 799 unsigned char *setup_packet; /* (in) setup packet (control only) */ 800 dma_addr_t setup_dma; /* (in) dma addr for setup_packet */ 801 int start_frame; /* (modify) start frame (ISO) */ 802 int number_of_packets; /* (in) number of ISO packets */ 803 int interval; /* (modify) transfer interval (INT/ISO) */ 804 int error_count; /* (return) number of ISO errors */ 805 void *context; /* (in) context for completion */ 806 usb_complete_t complete; /* (in) completion routine */ 807 struct usb_iso_packet_descriptor iso_frame_desc[0]; /* (in) ISO ONLY */ 808 }; drivers/usb/storage/usb.h: 105 /* we allocate one of these for every device that we remember */ 106 struct us_data { 107 /* The device we're working with 108 * It's important to note: 109 * (o) you must hold dev_semaphore to change pusb_dev 110 */ 111 struct semaphore dev_semaphore; /* protect pusb_dev */ 112 struct usb_device *pusb_dev; /* this usb_device */ 113 struct usb_interface *pusb_intf; /* this interface */ 114 struct us_unusual_dev *unusual_dev; /* device-filter entry */ 115 unsigned long flags; /* from filter initially */ 116 unsigned int send_bulk_pipe; /* cached pipe values */ 117 unsigned int recv_bulk_pipe; 118 unsigned int send_ctrl_pipe; 119 unsigned int recv_ctrl_pipe; 120 unsigned int recv_intr_pipe; 121 122 /* information about the device */ 123 char vendor[USB_STOR_STRING_LEN]; 124 char product[USB_STOR_STRING_LEN]; 125 char serial[USB_STOR_STRING_LEN]; 126 char *transport_name; 127 char *protocol_name; 128 u8 subclass; 129 u8 protocol; 130 u8 max_lun; 131 132 u8 ifnum; /* interface number */ 133 u8 ep_bInterval; /* interrupt interval */ 134 135 /* function pointers for this device */ 136 trans_cmnd transport; /* transport function */ 137 trans_reset transport_reset; /* transport device reset */ 138 proto_cmnd proto_handler; /* protocol handler */ 139 140 /* SCSI interfaces */ 141 struct Scsi_Host *host; /* our dummy host data */ 142 struct scsi_cmnd *srb; /* current srb */ 143 144 /* thread information */ 145 int pid; /* control thread */ 146 147 /* control and bulk communications data */ 148 struct urb *current_urb; /* USB requests */ 149 struct usb_ctrlrequest *cr; /* control requests */ 150 struct usb_sg_request current_sg; /* scatter-gather req. */ 151 unsigned char *iobuf; /* I/O buffer */ 152 dma_addr_t cr_dma; /* buffer DMA addresses */ 153 dma_addr_t iobuf_dma; 154 155 /* mutual exclusion and synchronization structures */ 156 struct semaphore sema; /* to sleep thread on */ 157 struct completion notify; /* thread begin/end */ 158 wait_queue_head_t dev_reset_wait; /* wait during reset */ 159 wait_queue_head_t scsi_scan_wait; /* wait before scanning */ 160 struct completion scsi_scan_done; /* scan thread end */ 161 162 /* subdriver information */ 163 void *extra; /* Any extra data */ 164 extra_data_destructor extra_destructor;/* extra data destructor */ 165 }; struct usb_ctrlrequest结构指针, usb规范规定了一个控制请求的格式为一个8个字节的 数据包, 而struct usb_ctrlrequest正是专门为此而准备的8个字节的一个变量,所以控制传输中总 会用到她.她的 定义在include/linux/usb_ch9.h中: 103 struct usb_ctrlrequest { 104 __u8 bRequestType; 105 __u8 bRequest; 106 __le16 wValue; 107 __le16 wIndex; 77 108 __le16 wLength; 109 } __attribute__ ((packed)); 需要说明一点,在usb spec中,不叫cr,而叫setup packet,在struct urb里边就有这么一个名字 一样的成员, 在usb mass storage bulk only transport协议里面,规定的很清楚,要发送GET MAX LUN请求, 必须把bmRequestType设置为device to host,class,interface,同时把bRequest设置为254(FEh), 即咱们这里的0xfe,而wValue设置为0,wIndex设置为接口的编号,最后wLength设置为1. byte0: bmRequestType,注意,在刚才咱们代码中数据结构struct ctrlrequest里边是写的 bRequestType,但是她们对应的是相同的冬冬.而之所以usb协议里写成bmRequestType,是因为她实 际上又是一个位图(m表示map),也就是说,尽管她只有1个byte,但是她仍然是当作8位来用.她的8位 的含义是: D7: 控制传输数据传输的方向,0表示方向为主机到设备,1表示方向为设备到主机.(有时控制传 输除了发命令阶段以外,可能还有数据传输阶段,此处表示的是在数据传输那个阶段的传输方向.) D6...5: 请求的类型,0称为类型(Standard),1称为Class,2称为Vendor,3则是保留的, 不能使用. D4...0: 接收者,0表示设备,1表示接口,2表示端点,3表示其它,4...31都是保留的,不能使用. 定义于include/linux/usb.h static inline void usb_fill_control_urb (struct urb *urb, struct usb_device *dev, unsigned int pipe, unsigned char *setup_packet, void *transfer_buffer, int buffer_length, usb_complete_t complete, void *context) { spin_lock_init(&urb->lock); urb->dev = dev; urb->pipe = pipe; urb->setup_packet = setup_packet; urb->transfer_buffer = transfer_buffer; urb->transfer_buffer_length = buffer_length; urb->complete = complete; urb->context = context; }