阿扁"辞职"了，kde4发布了，更让我激动的是，英雄志过两天又有更新了，这部连载长达8年的小说，终于要进入精彩的大结局。卢云的命运究竟如何？观海云远，四个性格理念完全不同的人，谁是好，谁是坏，谁是对，谁是错？何谓正道？
接着上回说，usb_hcd_pci_probe这个函数在"我是UHCI"中也有讨论，不过我想按照我的思路写下去。
46/**//**47*usb_hcd_pci_probe-initializePCI-basedHCDs48*@dev:USBHostControllerbeingprobed49*@id:pcihotplugidconnectingcontrollertoHCDframework50*Context:!in_interrupt()51*52*AllocatesbasicPCIresourcesforthisUSBhostcontroller,and53*theninvokesthestart()methodfortheHCDassociatedwithit54*throughthehotplugentry’sdriver_data.55*56*StorethisfunctionintheHCD’sstructpci_driverasprobe().57*/58intusb_hcd_pci_probe(structpci_dev*dev,conststructpci_device_id*id)59…{60structhc_driver*driver;61structusb_hcd*hcd;62intretval;6364if(usb_disabled())65return-ENODEV;6667if(!id||!(driver=(structhc_driver*)id->driver_data))68return-EINVAL;6970if(pci_enable_device(dev)<0)71return-ENODEV;72dev->current_state=PCI_D0;73dev->dev.power.power_state=PMSG_ON;7475if(!dev->irq)…{76dev_err(&dev->dev,77"FoundHCwithnoIRQ.CheckBIOS/PCI%ssetup! ",78pci_name(dev));79retval=-ENODEV;80gotoerr1;81}8283hcd=usb_create_hcd(driver,&dev->dev,pci_name(dev));84if(!hcd)…{85retval=-ENOMEM;86gotoerr1;87}8889if(driver->flags&HCD_MEMORY)…{//EHCI,OHCI90hcd->rsrc_start=pci_resource_start(dev,0);91hcd->rsrc_len=pci_resource_len(dev,0);92if(!request_mem_region(hcd->rsrc_start,hcd->rsrc_len,93driver->description))…{94dev_dbg(&dev->dev,"controlleralreadyinuse ");95retval=-EBUSY;96gotoerr2;97}98hcd->regs=ioremap_nocache(hcd->rsrc_start,hcd->rsrc_len);99if(hcd->regs==NULL)…{100dev_dbg(&dev->dev,"errormappingmemory ");101retval=-EFAULT;102gotoerr3;103}104105}else…{//UHCI106intregion;107108for(region=0;region<PCI_ROM_RESOURCE;region++)…{109if(!(pci_resource_flags(dev,region)&110IORESOURCE_IO))111continue;112113hcd->rsrc_start=pci_resource_start(dev,region);114hcd->rsrc_len=pci_resource_len(dev,region);115if(request_region(hcd->rsrc_start,hcd->rsrc_len,116driver->description))117break;118}119if(region==PCI_ROM_RESOURCE)…{120dev_dbg(&dev->dev,"noi/oregionsavailable ");121retval=-EBUSY;122gotoerr1;123}124}125126pci_set_master(dev);127128retval=usb_add_hcd(hcd,dev->irq,IRQF_SHARED);129if(retval!=0)130gotoerr4;131returnretval;132133err4:134if(driver->flags&HCD_MEMORY)…{135iounmap(hcd->regs);136err3:137release_mem_region(hcd->rsrc_start,hcd->rsrc_len);138}else139release_region(hcd->rsrc_start,hcd->rsrc_len);140err2:141usb_put_hcd(hcd);142err1:143pci_disable_device(dev);144dev_err(&dev->dev,"init%sfail,%d ",pci_name(dev),retval);145returnretval;146}
64行，usb_disabled()判断内核有没有开启支持usb，要是这都不支持，一切都免谈。
70行，pci_enable_device()这是对ehci三类接口中的pci configuration space进行操作，设置其中某个寄存器的值，使设备处于工作状态。调用pci_read_config_word()和pci_write_config_word来读写pci配置空间的寄存器。pci_enable_device -> pci_enable_device_bars -> do_pci_enable_device … 原理不难，只要对照spec可以看懂。
72，73是电源管理的内容。75判断设备的中断号是否为空。83，usb_create_hcd() 创建一个usb_hcd机构体。1480/**//**1481*usb_create_hcd-createandinitializeanHCDstructure1482*@driver:HCdriverthatwillusethishcd1483*@dev:deviceforthisHC,storedinhcd->self.controller1484*@bus_name:valuetostoreinhcd->self.bus_name1485*Context:!in_interrupt()1486*1487*Allocateastructusb_hcd,withextraspaceattheendforthe1488*HCdriver’sprivatedata.Initializethegenericmembersofthe1489*hcdstructure.1490*1491*Ifmemoryisunavailable,returnsNULL.1492*/1493structusb_hcd*usb_create_hcd(conststructhc_driver*driver,1494structdevice*dev,char*bus_name)1495…{1496structusb_hcd*hcd;14971498hcd=kzalloc(sizeof(*hcd)+driver->hcd_priv_size,GFP_KERNEL);1499if(!hcd)…{1500dev_dbg(dev,"hcdallocfailed ");1501returnNULL;1502}1503dev_set_drvdata(dev,hcd);1504kref_init(&hcd->kref);15051506usb_bus_init(&hcd->self);1507hcd->self.controller=dev;1508hcd->self.bus_name=bus_name;1509hcd->self.uses_dma=(dev->dma_mask!=NULL);15101511init_timer(&hcd->rh_timer);1512hcd->rh_timer.function=rh_timer_func;1513hcd->rh_timer.data=(unsignedlong)hcd;1514#ifdefCONFIG_PM1515INIT_WORK(&hcd->wakeup_work,hcd_resume_work);1516#endif15171518hcd->driver=driver;1519hcd->product_desc=(driver->product_desc)?driver->product_desc:1520"USBHostController";15211522returnhcd;1523}一下子出现了很多数据结构，现在有必要捋一捋它们之间的关系。(1)描述驱动的数据结构ehci主控器的驱动程序需要包括些什么东西？站在pci总线的角度来说，ehci是一个pci的设备，驱动程序里面必须提供操作ehci设备，比如开启(start)，关闭(stop)，重启(reset)，中断的函数。另外，站在usb控制器的角度来说，驱动程序里面还要与底层usb系统交互的函数，如插入/删除urb(rb_enqueue, urb_dequeue)。pci_driver ehci_pci_driver{ ……….id_table = pci_ids, ————>driver_data =(unsigned long) &ehci_pci_hc_driver, .probe = usb_hcd_pci_probe}hc_driver ehci_pci_hc_driver{ ………hcd_priv_size =sizeof(struct ehci_hcd),.irq =ehci_irq, .reset =ehci_pci_setup,.start =ehci_run,.stop =ehci_stop,.shutdown =ehci_shutdown,.urb_enqueue =ehci_urb_enqueue,.urb_dequeue =ehci_urb_dequeue,}(2)描述设备的数据结构usb_hcd{ ……..usb_bus .self .hcd_priv = ehci_hcd}usb_hcd交大人甲有过论述：linux那些事儿 之 戏说USB(28)设备的生命线(七)http://blog.csdn.net/fudan_abc/archive/2007/10/18/1831459.aspxusb_hcd注释上说USB Host Controller Driver，但我更愿意认为它是一个描述一个usb主控制器设备的数据结构。usb_hcd描述了usb主控制器共有的属性，usb_hcd.hcd_priv指向了特定的主控制器数据结构，它描述各自特有的属性。对ehci，是ehci_hcd，对uhci，是uhci_hcd。usb_hcd的成员usb_bus self 是HCD bus-glue layer，usb主控器与总线之间粘合剂。这样，1498就好理解了。1506行usb_bus_init初始化usb_hcd.self。 1511-1513初始化 root harbor 计时器。然后就有返回到usb_hcd_pci_probe()就是去旅行。牵着彼此的手，
