📄 linux设备驱动之usb主机控制器驱动分析-(2)_linux技术文章_linux_操作系统2.htm
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bus_name:OHCI对应的pci_dev的name<BR> <BR>在这里,注意一下hcd内存的分配.如下示:<BR>hcd =
kzalloc(sizeof(*hcd) + driver->hcd_priv_size, GFP_KERNEL);<BR>我们知道,struct
usb_hcd是一个位于usb_core下的东东,这个东东所有的host control都会用到.那么hcd就有一个私有区结构,用来表示host
control之间不同的数据结构.而其它们相同的结构保存在struct usb_hcd中.这个hcd_priv成员在struct
usb_hcd被定义成了0项数组的形式,而大小则是由hc_driver的hcd_priv_size项来指定的.<BR> <BR>struct
usb_hcd结构很庞大.这里不方便将其全部列出.只来说明一下在这里会用到的成员:<BR>1:self成员: 我们可以这想思考.每条USB总线上只有一个host
control.每个host control都对应着一条总线. 这个self成员就是表示hcd所对应的USB总线.
self.controller表示该总线上的控制器,也就是UHCI对应的pci_dev中封装的struct device. Self.
bus_name表示该总线的名称.也就是OHCI对应的pci_dev的名称.self. uses_dma来表示该总线上的控制器是否使用DMA<BR>2:
rh_timer成员:该成员是一个定时器,用来轮询控制器的根集线器的状态改变,通常用做电源管理.在这里不加详分析.<BR>2:
driver成员:表示该hcd对应驱动.<BR>总而言之,
usb_create_hcd就是对hcd的各项成员赋值.<BR> <BR>相比之下usb_add_hcd()的代码就比较繁杂了.下面以分段的形式分析如下:<BR>int
usb_add_hcd(struct usb_hcd
*hcd,<BR> unsigned int irqnum,
unsigned long irqflags)<BR>{<BR> int
retval;<BR> struct usb_device
*rhdev;<BR> <BR> dev_info(hcd->self.controller,
"%s\n", hcd->product_desc);<BR> <BR>
hcd->authorized_default = hcd->wireless? 0 :
1;<BR> set_bit(HCD_FLAG_HW_ACCESSIBLE,
&hcd->flags);<BR> <BR> /* HC is in reset
state, but accessible. Now do the one-time
init,<BR> * bottom up so that hcds can customize
the root hubs before khubd<BR> * starts talking to
them. (Note, bus id is assigned early too.)<BR>
*/<BR> //创建pool<BR>
if ((retval = hcd_buffer_create(hcd)) != 0)
{<BR>
dev_dbg(hcd->self.controller, "pool alloc
failed\n");<BR> return
retval;<BR> }<BR>在我们分析的流程中,
Hcd->wireless默认为0.相应的hcd->authorized_default也被置为了0.然后将hcd->flags置为HCD_FLAG_HW_ACCESSIBLE.表示该USB控制器是可以访问的.最后在hcd_buffer_create中,因为hc_driver的flags标志被末置HCD_LOCAL_MEM.该函数在这里什么都不做就返回0了.<BR> <BR>
//注册usb_bus<BR> if ((retval =
usb_register_bus(&hcd->self)) <
0)<BR> goto
err_register_bus;<BR> <BR> //分配并初始化root
hub<BR> if ((rhdev = usb_alloc_dev(NULL,
&hcd->self, 0)) == NULL)
{<BR>
dev_err(hcd->self.controller, "unable to allocate root
hub\n");<BR> retval =
-ENOMEM;<BR> goto
err_allocate_root_hub;<BR> }<BR>
//OHCI定义于usb1.1只能支持全速<BR> rhdev->speed =
(hcd->driver->flags & HCD_USB2) ? USB_SPEED_HIGH
:<BR>
USB_SPEED_FULL;<BR> hcd->self.root_hub =
rhdev;<BR> <BR> /* wakeup flag init defaults to
"everything works" for root hubs,<BR> * but
drivers can override it in reset() if needed, along
with<BR> * recording the overall controller's
system wakeup capability.<BR>
*/<BR> device_init_wakeup(&rhdev->dev,
1);<BR>在前面.我们看到了在hcd的self成员的赋值过程,而所有的总线信息都要保存在一个地方,在其它的地方会用到这些总线信息.所以usb_register_bus()对应的工作就是在全局变量busmap的位图中找到没有被使用的位做为usb_bus的序号(我们暂且称呼它为USB总线号).然后为该总线注册一个属于usb_host_class类的设备.以后在/sys/class/host中就可以看到该bus对应的目录了.最后,将总线链接到usb_bus_list链表中.<BR>然后,每一个USB控制器都有一个根集线器.这里也要为总线下的根集钱器创建相应的结构,
usb_alloc_dev()用来生成并初始化的usb_device结构.这个函数比较重要,在后面给出这个函数的详细分析.<BR>因为OHCI是USB1.1的设备,所以,根集线器的speed会被定义成USB_SPEED_FULL(全速).最后将这个根集线器关联到总线中.<BR>device_init_wakeup(&rhdev->dev,
1)是和总线相关的,忽略它吧 :-)<BR> /* "reset" is misnamed; its role
is now one-time init. the controller<BR> * should
already have been reset (and boot firmware kicked off
etc).<BR> */<BR> if
(hcd->driver->reset && (retval = hcd->driver->reset(hcd))
< 0) {<BR>
dev_err(hcd->self.controller,</P>
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