linux裝置驅動(26)usb驅動-基本資料和api
阿新 • • 發佈：2020-07-09
usb驅動目錄drivers/usb/*
usb/serial：usb 序列裝置驅動 （例如usb 3G卡、藍芽等）；
usb/storage：usb 大儲量磁碟驅動（u盤）；
usb/host：usb host usb主機控制器驅動（嵌入式otg：dwc_otg）；
usb/core：usb 核心一些處理程式碼，所有的驅動相關處理都在這裡，也都註冊到它裡面。
usb/usb-skeleton.c：經典的usb客戶驅動框架，可以參考。
1 主要資料結構體
1.1 usb device裝置結構體
定義位於：include\linux\usb.h
1 struct usb_device { 2 intdevnum;//裝置號，是在USB匯流排的地址 3 char devpath[16];//用於訊息的裝置ID字串 4 u32 route; 5 enum usb_device_state state;//裝置狀態：已配置、未連線等 6 enum usb_device_speed speed; 7 8 struct usb_tt *tt;//處理傳輸者資訊；用於低速、全速裝置和高速HUB 9 int ttport;//位於tt HUB的裝置口 10 11 unsigned inttoggle[2];//每個端點的佔一位，表明端點的方向([0] = IN, [1] = OUT) 12 13 struct usb_device *parent;//上一級HUB指標 14 struct usb_bus *bus;//匯流排指標 15 struct usb_host_endpoint ep0;//端點0資料 16 17 struct device dev;//一般的裝置介面資料結構 18 19 struct usb_device_descriptor descriptor;//USB裝置描述符 20 struct usb_host_bos *bos;21 struct usb_host_config *config;//裝置的所有配置結構體,配置結構體裡包含了配置描述符 22 23 struct usb_host_config *actconfig;/被啟用的裝置配置 24 struct usb_host_endpoint *ep_in[16];//輸入端點陣列 25 struct usb_host_endpoint *ep_out[16];//輸出端點陣列 26 char **rawdescriptors;//每個配置的raw描述符 27 28 unsigned short bus_mA;//可使用的匯流排電流 29 u8 portnum;//父埠號 30 u8 level;//USB HUB的層數 31 32 unsigned can_submit:1;//URB可被提交標誌 33 unsigned persist_enabled:1;//USB_PERSIST使能標誌 34 unsigned have_langid:1;//string_langid存在標誌 35 unsigned authorized:1; 36 unsigned authenticated:1; 37 unsigned wusb:1;//無線USB標誌 38 unsigned lpm_capable:1; 39 unsigned usb2_hw_lpm_capable:1; 40 unsigned usb2_hw_lpm_enabled:1; 41 unsigned usb3_lpm_enabled:1; 42 int string_langid;//字串語言ID 43 44 /* static strings from the device */裝置的靜態字串 45 char *product;//產品名 46 char *manufacturer;//廠商名 47 char *serial;//產品串號 48 49 struct list_head filelist;//此裝置開啟的usbfs檔案 50 51 int maxchild;//（若為HUB）介面數 52 53 u32 quirks; 54 atomic_t urbnum;//這個裝置所提交的URB計數 55 56 unsigned long active_duration;//啟用後使用計時 57 58 #ifdef CONFIG_PM //電源管理相關 59 unsigned long connect_time; 60 61 unsigned do_remote_wakeup:1; 62 unsigned reset_resume:1; 63 unsigned port_is_suspended:1; 64 #endif 65 struct wusb_dev *wusb_dev; 66 int slot_id; 67 enum usb_device_removable removable; 68 struct usb3_lpm_parameters u1_params; 69 struct usb3_lpm_parameters u2_params; 70 unsigned lpm_disable_count; 71 }
1.2 usb driver結構體
代表usb驅動
1 struct usb_driver { 2 const char *name; 3 4 int (*probe) (struct usb_interface *intf, 5 const struct usb_device_id *id); 6 7 void (*disconnect) (struct usb_interface *intf); 8 9 int (*unlocked_ioctl) (struct usb_interface *intf, unsigned int code, 10 void *buf); 11 12 int (*suspend) (struct usb_interface *intf, pm_message_t message); 13 int (*resume) (struct usb_interface *intf); 14 int (*reset_resume)(struct usb_interface *intf); 15 16 int (*pre_reset)(struct usb_interface *intf); 17 int (*post_reset)(struct usb_interface *intf); 18 19 const struct usb_device_id *id_table; 20 21 struct usb_dynids dynids; 22 struct usbdrv_wrap drvwrap; 23 unsigned int no_dynamic_id:1; 24 unsigned int supports_autosuspend:1; 25 unsigned int disable_hub_initiated_lpm:1; 26 unsigned int soft_unbind:1; 27 }
1.3 usb bus結構體
代表usb匯流排
1 struct usb_bus { 2 struct device *controller; /* host/master side hardware */ 3 int busnum; /* Bus number (in order of reg) */ 4 const char *bus_name; /* stable id (PCI slot_name etc) */ 5 u8 uses_dma; /* Does the host controller use DMA? */ 6 u8 uses_pio_for_control; /* 7 * Does the host controller use PIO 8 * for control transfers? 9 */ 10 u8 otg_port; /* 0, or number of OTG/HNP port */ 11 unsigned is_b_host:1; /* true during some HNP roleswitches */ 12 unsigned b_hnp_enable:1; /* OTG: did A-Host enable HNP? */ 13 unsigned no_stop_on_short:1; /* 14 * Quirk: some controllers don't stop 15 * the ep queue on a short transfer 16 * with the URB_SHORT_NOT_OK flag set. 17 */ 18 unsigned sg_tablesize; /* 0 or largest number of sg list entries */ 19 20 int devnum_next; /* Next open device number in 21 * round-robin allocation */ 22 23 struct usb_devmap devmap; /* device address allocation map */ 24 struct usb_device *root_hub; /* Root hub */ 25 struct usb_bus *hs_companion; /* Companion EHCI bus, if any */ 26 struct list_head bus_list; /* list of busses */ 27 28 int bandwidth_allocated; /* on this bus: how much of the time 29 * reserved for periodic (intr/iso) 30 * requests is used, on average? 31 * Units: microseconds/frame. 32 * Limits: Full/low speed reserve 90%, 33 * while high speed reserves 80%. 34 */ 35 int bandwidth_int_reqs; /* number of Interrupt requests */ 36 int bandwidth_isoc_reqs; /* number of Isoc. requests */ 37 38 unsigned resuming_ports; /* bit array: resuming root-hub ports */ 39 40 #if defined(CONFIG_USB_MON) || defined(CONFIG_USB_MON_MODULE) 41 struct mon_bus *mon_bus; /* non-null when associated */ 42 int monitored; /* non-zero when monitored */ 43 #endif 44 }
1.4usb_interface 結構體
1 struct usb_interface { 2 /* array of alternate settings for this interface, 3 * stored in no particular order */ 4 struct usb_host_interface *altsetting; 5 6 struct usb_host_interface *cur_altsetting; /* the currently //當前使用的設定，usb_host_interface中desc成員就是usb介面描述符 7 * active alternate setting */ 8 unsigned num_altsetting; /* number of alternate settings */可選的設定數量 9 10 /* If there is an interface association descriptor then it will list 11 * the associated interfaces */ 12 struct usb_interface_assoc_descriptor *intf_assoc; 13 14 int minor; /* minor number this interface is//如果繫結到這個介面的 USB 驅動使用 USB 主裝置號, 這個變數包含由 USB 核心分配給介面的次裝置號. 這隻在一個成功的呼叫 usb_register_dev後才有效 15 * bound to */ 16 enum usb_interface_condition condition; /* state of binding */ 17 unsigned sysfs_files_created:1; /* the sysfs attributes exist */ 18 unsigned ep_devs_created:1; /* endpoint "devices" exist */ 19 unsigned unregistering:1; /* unregistration is in progress */ 20 unsigned needs_remote_wakeup:1; /* driver requires remote wakeup */ 21 unsigned needs_altsetting0:1; /* switch to altsetting 0 is pending */ 22 unsigned needs_binding:1; /* needs delayed unbind/rebind */ 23 unsigned reset_running:1; 24 unsigned resetting_device:1; /* true: bandwidth alloc after reset */ 25 26 struct device dev; /* interface specific device info */ 27 struct device *usb_dev; 28 atomic_t pm_usage_cnt; /* usage counter for autosuspend */ 29 struct work_struct reset_ws; /* for resets in atomic context */ 30 }
1.5usb_host_interface 結構體
具體到介面描述符，它當然就是描述介面本身的資訊的。一個介面可以有多個設定，使用不同的設定，描述介面的資訊會有些不同，所以介面描述符並沒有放在struct usb_interface結構裡，而是放在表示介面設定的struct usb_host_interface結構裡。
1 struct usb_host_interface { 2 struct usb_interface_descriptor desc;//usb介面描述符 3 4 int extralen; 5 unsigned char *extra; /* Extra descriptors */ 6 7 /* array of desc.bNumEndpoint endpoints associated with this 8 * interface setting. these will be in no particular order. 9 */ 10 struct usb_host_endpoint *endpoint;//這個設定所使用的端點 11 12 char *string; /* iInterface string, if present */ 13 }
1.6 usb配置結構體
1 struct usb_host_config { 2 struct usb_config_descriptor desc;//usb配置結構體 3 4 char *string; /* iConfiguration string, if present */ 5 6 /* List of any Interface Association Descriptors in this 7 * configuration. */ 8 struct usb_interface_assoc_descriptor *intf_assoc[USB_MAXIADS]; 9 10 /* the interfaces associated with this configuration, 11 * stored in no particular order */ 12 struct usb_interface *interface[USB_MAXINTERFACES];//配置所包含的介面，這個陣列的順序未必是按照配置裡介面號的順序 13 14 /* Interface information available even when this is not the 15 * active configuration */ 16 struct usb_interface_cache *intf_cache[USB_MAXINTERFACES];//usb介面的快取 17 18 unsigned char *extra; /* Extra descriptors */ 19 int extralen; 20 }
1.7 usb端點結構體
1 struct usb_host_endpoint {
2 struct usb_endpoint_descriptor desc;//usb端點描述符
3 struct usb_ss_ep_comp_descriptor ss_ep_comp;
4 struct list_head urb_list;//端點要處理的urb佇列.urb是usb通訊的主角，裝置中的每個端點都可以處理一個urb佇列.要想和你的usb通訊，就得建立一個urb，並且為它賦好值，交給咱們的usb core，它會找到合適的host controller，從而進行具體的資料傳輸。
5 void *hcpriv;//這是提供給HCD（host controller driver）用的
6 struct ep_device *ep_dev; /* For sysfs info */
7
8 unsigned char *extra; /* Extra descriptors */
9 int extralen;
10 int enabled;
11 };
2 主要api
2.1 usb驅動註冊函式
定義位於：include\linux\usb.h和drivers\usb\core\driver.c
1 /* use a define to avoid include chaining to get THIS_MODULE & friends */ 2 #define usb_register(driver) \ 3 usb_register_driver(driver, THIS_MODULE, KBUILD_MODNAME) 4 5 int usb_register_driver(struct usb_driver *new_driver, struct module *owner, 6 const char *mod_name) 7 { 8 int retval = 0; 9 10 if (usb_disabled()) 11 return -ENODEV; 12 13 new_driver->drvwrap.for_devices = 0; 14 new_driver->drvwrap.driver.name = (char *) new_driver->name; 15 new_driver->drvwrap.driver.bus = &usb_bus_type; 16 new_driver->drvwrap.driver.probe = usb_probe_interface; 17 new_driver->drvwrap.driver.remove = usb_unbind_interface; 18 new_driver->drvwrap.driver.owner = owner; 19 new_driver->drvwrap.driver.mod_name = mod_name; 20 spin_lock_init(&new_driver->dynids.lock); 21 INIT_LIST_HEAD(&new_driver->dynids.list); 22 23 retval = driver_register(&new_driver->drvwrap.driver);//註冊usb驅動 24 if (retval) 25 goto out; 26 27 retval = usb_create_newid_files(new_driver); 28 if (retval) 29 goto out_newid; 30 31 pr_info("%s: registered new interface driver %s\n", 32 usbcore_name, new_driver->name); 33 34 out: 35 return retval; 36 37 out_newid: 38 driver_unregister(&new_driver->drvwrap.driver); 39 40 printk(KERN_ERR "%s: error %d registering interface " 41 " driver %s\n", 42 usbcore_name, retval, new_driver->name); 43 goto out; 44 }
1.2 usb裝置分配函式
1 struct usb_device *usb_alloc_dev(struct usb_device *parent, 2 struct usb_bus *bus, unsigned port1) 3 { 4 struct usb_device *dev; 5 struct usb_hcd *usb_hcd = bus_to_hcd(bus); 6 unsigned root_hub = 0; 7 8 dev = kzalloc(sizeof(*dev), GFP_KERNEL);//分配usb裝置 9 if (!dev) 10 return NULL; 11 12 if (!usb_get_hcd(usb_hcd)) { 13 kfree(dev); 14 return NULL; 15 } 16 /* Root hubs aren't true devices, so don't allocate HCD resources */ 17 if (usb_hcd->driver->alloc_dev && parent && 18 !usb_hcd->driver->alloc_dev(usb_hcd, dev)) { 19 usb_put_hcd(bus_to_hcd(bus)); 20 kfree(dev); 21 return NULL; 22 } 23 24 device_initialize(&dev->dev);//初始化usb裝置 25 dev->dev.bus = &usb_bus_type;//指定usb匯流排 26 dev->dev.type = &usb_device_type; 27 dev->dev.groups = usb_device_groups; 28 dev->dev.dma_mask = bus->controller->dma_mask; 29 set_dev_node(&dev->dev, dev_to_node(bus->controller)); 30 dev->state = USB_STATE_ATTACHED; 31 dev->lpm_disable_count = 1; 32 atomic_set(&dev->urbnum, 0); 33 34 INIT_LIST_HEAD(&dev->ep0.urb_list); 35 dev->ep0.desc.bLength = USB_DT_ENDPOINT_SIZE; 36 dev->ep0.desc.bDescriptorType = USB_DT_ENDPOINT; 37 /* ep0 maxpacket comes later, from device descriptor */ 38 usb_enable_endpoint(dev, &dev->ep0, false); 39 dev->can_submit = 1; 40 41 /* Save readable and stable topology id, distinguishing devices 42 * by location for diagnostics, tools, driver model, etc. The 43 * string is a path along hub ports, from the root. Each device's 44 * dev->devpath will be stable until USB is re-cabled, and hubs 45 * are often labeled with these port numbers. The name isn't 46 * as stable: bus->busnum changes easily from modprobe order, 47 * cardbus or pci hotplugging, and so on. 48 */ 49 if (unlikely(!parent)) { 50 dev->devpath[0] = '0'; 51 dev->route = 0; 52 53 dev->dev.parent = bus->controller; 54 dev_set_name(&dev->dev, "usb%d", bus->busnum); 55 root_hub = 1; 56 } else { 57 /* match any labeling on the hubs; it's one-based */ 58 if (parent->devpath[0] == '0') { 59 snprintf(dev->devpath, sizeof dev->devpath, 60 "%d", port1); 61 /* Root ports are not counted in route string */ 62 dev->route = 0; 63 } else { 64 snprintf(dev->devpath, sizeof dev->devpath, 65 "%s.%d", parent->devpath, port1); 66 /* Route string assumes hubs have less than 16 ports */ 67 if (port1 < 15) 68 dev->route = parent->route + 69 (port1 << ((parent->level - 1)*4)); 70 else 71 dev->route = parent->route + 72 (15 << ((parent->level - 1)*4)); 73 } 74 75 dev->dev.parent = &parent->dev; 76 dev_set_name(&dev->dev, "%d-%s", bus->busnum, dev->devpath);//設定usb裝置名字 77 78 /* hub driver sets up TT records */ 79 } 80 81 dev->portnum = port1; 82 dev->bus = bus; 83 dev->parent = parent; 84 INIT_LIST_HEAD(&dev->filelist); 85 86 #ifdef CONFIG_PM 87 pm_runtime_set_autosuspend_delay(&dev->dev, 88 usb_autosuspend_delay * 1000); 89 dev->connect_time = jiffies; 90 dev->active_duration = -jiffies; 91 #endif 92 if (root_hub) /* Root hub always ok [and always wired] */ 93 dev->authorized = 1; 94 else { 95 dev->authorized = usb_hcd->authorized_default; 96 dev->wusb = usb_bus_is_wusb(bus)? 1 : 0; 97 } 98 return dev; 99 }
1.3 usb初始化函式
包括usb 匯流排的初始化，usb驅動的註冊。usb_init 定義位於：drivers\usb\core\usb.c
1 static int __init usb_init(void) 2 { 3 int retval; 4 if (nousb) { 5 pr_info("%s: USB support disabled\n", usbcore_name); 6 return 0; 7 } 8 usb_init_pool_max(); 9 10 retval = usb_debugfs_init(); 11 if (retval) 12 goto out; 13 14 usb_acpi_register(); 15 retval = bus_register(&usb_bus_type);//usb匯流排註冊 16 if (retval) 17 goto bus_register_failed; 18 retval = bus_register_notifier(&usb_bus_type, &usb_bus_nb); 19 if (retval) 20 goto bus_notifier_failed; 21 retval = usb_major_init(); 22 if (retval) 23 goto major_init_failed; 24 retval = usb_register(&usbfs_driver);//usb驅動註冊 25 if (retval) 26 goto driver_register_failed; 27 retval = usb_devio_init(); 28 if (retval) 29 goto usb_devio_init_failed; 30 retval = usb_hub_init(); 31 if (retval) 32 goto hub_init_failed; 33 retval = usb_register_device_driver(&usb_generic_driver, THIS_MODULE); 34 if (!retval) 35 goto out; 36 37 usb_hub_cleanup(); 38 hub_init_failed: 39 usb_devio_cleanup(); 40 usb_devio_init_failed: 41 usb_deregister(&usbfs_driver); 42 driver_register_failed: 43 usb_major_cleanup(); 44 major_init_failed: 45 bus_unregister_notifier(&usb_bus_type, &usb_bus_nb); 46 bus_notifier_failed: 47 bus_unregister(&usb_bus_type); 48 bus_register_failed: 49 usb_acpi_unregister(); 50 usb_debugfs_cleanup(); 51 out: 52 return retval; 53 }
usb匯流排的定義初始化，位於drivers\usb\core\driver.c：
1 struct bus_type usb_bus_type = { 2 .name = "usb", 3 .match = usb_device_match, 4 .uevent = usb_uevent, 5 };