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<P>IOS off this hardware and reset if the controller<BR>
* isn't already safely quiescent.<BR>
*/<BR>
check_and_reset_hc(uhci);<BR> return
0;<BR>}<BR>代码中hcd_to_uhci()的操作就不做详细分析了.在分配usb_hcd的内存时就已经分析过.<BR>结合UHCI
spec来理解这段代码.spec中规定.从I/O空间的0x10处开始,为端口控制状态寄存器(PORTSC).占有两个字节.这个端口也是指UHCI控制器的root
hub端口.该寄存器用来表示端口的状态,和操作相应端口.协议中并没有规定一个UHCI有多少个端口,但规定不能够超过8个.另外,协议中规定,PORTSC的bit7始终为1.因此可以根据这个特征来判断端口是否存在.另外,寄存器中的位全为1也是不正常的.<BR>这样就可以计算出UHCI的root
hub有多少个端口.然后将值存放到uhci的rh_numports中.<BR>注意代码中取寄存器值的*2操作.这是因为每个PORTSC占两个字节.<BR>剩下的代码就只有check_and_reset_hc(
)了.该函数用来检查UHCI是否需要重置.如果需要重置.那就进行UHCI的重置操作.代码如下:<BR>static void
check_and_reset_hc(struct uhci_hcd *uhci)<BR>{<BR> if
(uhci_check_and_reset_hc(to_pci_dev(uhci_dev(uhci)),
uhci->io_addr))<BR>
finish_reset(uhci);<BR>}<BR>先来分析uhci_check_and_reset_hc()的代码.如下所示:<BR>int
uhci_check_and_reset_hc(struct pci_dev *pdev, unsigned long
base)<BR>{<BR> u16 legsup;<BR>
unsigned int cmd, intr;<BR> <BR>
/*<BR> * When restarting a suspended controller,
we expect all the<BR> * settings to be the same as
we left them:<BR> *<BR>
* PIRQ and SMI disabled, no R/W bits set in
USBLEGSUP;<BR> * Controller is stopped
and configured with EGSM set;<BR> * No
interrupts enabled except possibly Resume Detect.<BR>
*<BR> * If any of these conditions are
violated we do a complete reset.<BR>
*/<BR> pci_read_config_word(pdev, UHCI_USBLEGSUP,
&legsup);<BR> if (legsup & ~(UHCI_USBLEGSUP_RO |
UHCI_USBLEGSUP_RWC)) {<BR>
dev_dbg(&pdev->dev, "%s: legsup =
0x%04x\n",<BR>
__FUNCTION__, legsup);<BR> goto
reset_needed;<BR>
}<BR> <BR> cmd = inw(base +
UHCI_USBCMD);<BR> if ((cmd & UHCI_USBCMD_RUN) ||
!(cmd & UHCI_USBCMD_CONFIGURE)
||<BR>
!(cmd & UHCI_USBCMD_EGSM))
{<BR> dev_dbg(&pdev->dev,
"%s: cmd =
0x%04x\n",<BR>
__FUNCTION__, cmd);<BR> goto
reset_needed;<BR>
}<BR> <BR> intr = inw(base +
UHCI_USBINTR);<BR> if (intr &
(~UHCI_USBINTR_RESUME)) {<BR>
dev_dbg(&pdev->dev, "%s: intr =
0x%04x\n",<BR>
__FUNCTION__, intr);<BR> goto
reset_needed;<BR> }<BR> return
0;<BR> <BR>reset_needed:<BR>
dev_dbg(&pdev->dev, "Performing full
reset\n");<BR> uhci_reset_hc(pdev,
base);<BR> return
1;<BR>}<BR>该函数的第一个参数为UHCI对应的pci_dev.第二个参数是I/O区间的起始地址.从代码中看来,有三种情况是需要重置的.这三种情况分别为:<BR>1:如果LEGACY
SUPPORT REGISTER寄存器中R/W属性位被置,那就需要重启. LEGACY SUPPORT REGISTER通常是用于legacy
键盘和鼠标.UHCI spec上对其有详细的定义.对照spec.所有R/W属性的位都是某种能力的使能开关.例如,bit13表示USB PIRQ
Enable.如果该位被置,表示设备能够产生中断.否则就不可以.<BR>因此,对于这样的位,应该将其初始化.也即将设备的功能关闭.这也很容易理解,为了R/W属性位被置就需要重启UHCI<BR> <BR>2:USB
CMD寄存器的UHCI_USBCMD_RUN被置为1,
UHCI_USBCMD_CONFIGURE和UHCI_USBCMD_EGSM位为0的时候需要重启.<BR>UHCI_USBCMD_RUN表示UHCI正在调度数据,处于运行状态.显然,这个时候是应该被重启的<BR>UHCI_USBCMD_CONFIGURE:这个位是由软件控制的,只是起一个标识作用,不会对硬件产生任何影响.如果该位为了1,表示UHCI正处于配置状态.没有处于配置状态,当然就可以重启了.<BR>UHCI_USBCMD_EGSM表示UHCI是否处于Global
Suspend mode.在这种模式下,是不会产生数据交互的.显然.如果该位为0.则表示该位不是Global Suspend
mode模式,当然就需要重启了.<BR> <BR>3:USB
INTR寄存器中除UHCI_USBINTR_RESUME如果其它位为1.则重启UHCI.<BR>在USB INTR寄存器中,bit4~bit15是保留的,始终为0.其它四位对应了UHCI的四种不同类型的中断,除了bit1表示的Resume
interrupt外,其它类型的应该全部都被关掉.<BR> <BR>如果不需要重启UHCI,直接返回0即可.如果需要重启,则会调转到uhci_reset_hc().代码如下:<BR>void
uhci_reset_hc(struct pci_dev *pdev, unsigned long
base)<BR>{<BR> /* Turn off PIRQ enable and SMI
enable. (This also turns off the<BR> *
BIOS's USB Legacy Support.) Turn off all the R/WC bits
too.<BR> */<BR>
pci_write_config_word(pdev, UHCI_USBLEGSUP,
UHCI_USBLEGSUP_RWC);<BR> <BR> /* Reset the HC -
this will force us to get a<BR> * new notification
of any already connected<BR> * ports due to the
virtual disconnect that it<BR> *
implies.<BR> */<BR>
outw(UHCI_USBCMD_HCRESET, base + UHCI_USBCMD);<BR>
mb();<BR> udelay(5);<BR> if
(inw(base + UHCI_USBCMD) &
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