usb suspend

ddv posted @ 2009年9月28日 19:09 in Linux driver , 15145 阅读

 driver/usb/core/hub.c

  1. /**
  2. * usb_reset_device - warn interface drivers and perform a USB port reset
  3. * @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
  4. *
  5. * Warns all drivers bound to registered interfaces (using their pre_reset
  6. * method), performs the port reset, and then lets the drivers know that
  7. * the reset is over (using their post_reset method).
  8. *
  9. * Return value is the same as for usb_reset_and_verify_device().
  10. *
  11. * The caller must own the device lock.  For example, it's safe to use
  12. * this from a driver probe() routine after downloading new firmware.
  13. * For calls that might not occur during probe(), drivers should lock
  14. * the device using usb_lock_device_for_reset().
  15. *
  16. * If an interface is currently being probed or disconnected, we assume
  17. * its driver knows how to handle resets.  For all other interfaces,
  18. * if the driver doesn't have pre_reset and post_reset methods then
  19. * we attempt to unbind it and rebind afterward.
  20. */
  21. int usb_reset_device(struct usb_device *udev)
  22. {
  23.         int ret;
  24.         int i;
  25.         struct usb_host_config *config = udev->actconfig;
  26.  
  27.         if (udev->state == USB_STATE_NOTATTACHED ||
  28.                         udev->state == USB_STATE_SUSPENDED) {
  29.                 dev_dbg(&udev->dev, "device reset not allowed in state %d\n",
  30.                                 udev->state);
  31.                 return -EINVAL;
  32.         }
  33.  
  34.         /* Prevent autosuspend during the reset */
  35.         usb_autoresume_device(udev);
  36.  
  37.         if (config) {
  38.                 for (i = 0; i < config->desc.bNumInterfaces; ++i) {
  39.                         struct usb_interface *cintf = config->interface[i];
  40.                         struct usb_driver *drv;
  41.                         int unbind = 0;
  42.  
  43.                         if (cintf->dev.driver) {
  44.                                 drv = to_usb_driver(cintf->dev.driver);
  45.                                 if (drv->pre_reset && drv->post_reset)
  46.                                         unbind = (drv->pre_reset)(cintf);
  47.                                 else if (cintf->condition ==
  48.                                                 USB_INTERFACE_BOUND)
  49.                                         unbind = 1;
  50.                                 if (unbind)
  51.                                         usb_forced_unbind_intf(cintf);
  52.                         }
  53.                 }
  54.         }
  55.  
  56.         ret = usb_reset_and_verify_device(udev);
  57.  
  58.         if (config) {
  59.                 for (i = config->desc.bNumInterfaces - 1; i >= 0; --i) {
  60.                         struct usb_interface *cintf = config->interface[i];
  61.                         struct usb_driver *drv;
  62.                         int rebind = cintf->needs_binding;
  63.  
  64.                         if (!rebind && cintf->dev.driver) {
  65.                                 drv = to_usb_driver(cintf->dev.driver);
  66.                                 if (drv->post_reset)
  67.                                         rebind = (drv->post_reset)(cintf);
  68.                                 else if (cintf->condition ==
  69.                                                 USB_INTERFACE_BOUND)
  70.                                         rebind = 1;
  71.                         }
  72.                         if (ret == 0 && rebind)
  73.                                 usb_rebind_intf(cintf);
  74.                 }
  75.         }
  76.  
  77.         usb_autosuspend_device(udev);
  78.         return ret;
  79. }

这个函数实现的功能：通知接口驱动并执行USB端口重置。参数udev就是想要重置的那个设备。预先通知所有的已绑定的注册了的接口，执行端口重置，并让驱动知道重置结束。27-32行，先判断一下这个设备，如果是USB_STATE_NOTATTACHED 或者USB_STATE_SUSPENDED，那么就打印该状态不允许重置并返回；35行，autoresume为防止在重置过程中autosuspend；37-54行，将当前配置的所有接口驱动和接口解绑；56行，真正的执行重置的函数，并做检验；58-75行，将当前配置的所有接口和接口驱动重新绑定；77行，打开autosuspend；最后返回。

  1. /**
  2. * usb_reset_and_verify_device - perform a USB port reset to reinitialize a device
  3. * @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
  4. *
  5. * WARNING - don't use this routine to reset a composite device
  6. * (one with multiple interfaces owned by separate drivers)!
  7. * Use usb_reset_device() instead.
  8. *
  9. * Do a port reset, reassign the device's address, and establish its
  10. * former operating configuration.  If the reset fails, or the device's
  11. * descriptors change from their values before the reset, or the original
  12. * configuration and altsettings cannot be restored, a flag will be set
  13. * telling khubd to pretend the device has been disconnected and then
  14. * re-connected.  All drivers will be unbound, and the device will be
  15. * re-enumerated and probed all over again.
  16. *
  17. * Returns 0 if the reset succeeded, -ENODEV if the device has been
  18. * flagged for logical disconnection, or some other negative error code
  19. * if the reset wasn't even attempted.
  20. *
  21. * The caller must own the device lock.  For example, it's safe to use
  22. * this from a driver probe() routine after downloading new firmware.
  23. * For calls that might not occur during probe(), drivers should lock
  24. * the device using usb_lock_device_for_reset().
  25. *
  26. * Locking exception: This routine may also be called from within an
  27. * autoresume handler.  Such usage won't conflict with other tasks
  28. * holding the device lock because these tasks should always call
  29. * usb_autopm_resume_device(), thereby preventing any unwanted autoresume.
  30. */
  31. static int usb_reset_and_verify_device(struct usb_device *udev)
  32. {
  33.         struct usb_device              *parent_hdev = udev->parent;
  34.         struct usb_hub      *parent_hub;
  35.         struct usb_device_descriptor    descriptor = udev->descriptor;
  36.         int                 i, ret = 0;
  37.         int                    port1 = udev->portnum;
  38.  
  39.         if (udev->state == USB_STATE_NOTATTACHED ||
  40.                         udev->state == USB_STATE_SUSPENDED) {
  41.                 dev_dbg(&udev->dev, "device reset not allowed in state %d\n",
  42.                                 udev->state);
  43.                 return -EINVAL;
  44.         }
  45.  
  46.         if (!parent_hdev) {
  47.                 /* this requires hcd-specific logic; see OHCI hc_restart() */
  48.                 dev_dbg(&udev->dev, "%s for root hub!\n", __func__);
  49.                 return -EISDIR;
  50.         }
  51.         parent_hub = hdev_to_hub(parent_hdev);
  52.  
  53.         set_bit(port1, parent_hub->busy_bits);
  54.         for (i = 0; i < SET_CONFIG_TRIES; ++i) {
  55.  
  56.                 /* ep0 maxpacket size may change; let the HCD know about it.
  57.                  * Other endpoints will be handled by re-enumeration. */
  58.                 usb_ep0_reinit(udev);
  59.                 ret = hub_port_init(parent_hub, udev, port1, i);
  60.                 if (ret >= 0 || ret == -ENOTCONN || ret == -ENODEV)
  61.                         break;
  62.         }
  63.         clear_bit(port1, parent_hub->busy_bits);
  64.  
  65.         if (ret < 0)
  66.                 goto re_enumerate;
  67.  
  68.         /* Device might have changed firmware (DFU or similar) */
  69.         if (descriptors_changed(udev, &descriptor)) {
  70.                 dev_info(&udev->dev, "device firmware changed\n");
  71.                 udev->descriptor = descriptor;  /* for disconnect() calls */
  72.                 goto re_enumerate;
  73.         }
  74.  
  75.         if (!udev->actconfig)
  76.                 goto done;
  77.  
  78.         ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
  79.                         USB_REQ_SET_CONFIGURATION, 0,
  80.                         udev->actconfig->desc.bConfigurationValue, 0,
  81.                         NULL, 0, USB_CTRL_SET_TIMEOUT);
  82.         if (ret < 0) {
  83.                 dev_err(&udev->dev,
  84.                         "can't restore configuration #%d (error=%d)\n",
  85.                         udev->actconfig->desc.bConfigurationValue, ret);
  86.                 goto re_enumerate;
  87.         }
  88.         usb_set_device_state(udev, USB_STATE_CONFIGURED);
  89.  
  90.         for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
  91.                 struct usb_interface *intf = udev->actconfig->interface[i];
  92.                 struct usb_interface_descriptor *desc;
  93.  
  94.                 /* set_interface resets host side toggle even
  95.                  * for altsetting zero.  the interface may have no driver.
  96.                  */
  97.                 desc = &intf->cur_altsetting->desc;
  98.                 ret = usb_set_interface(udev, desc->bInterfaceNumber,
  99.                         desc->bAlternateSetting);
  100.                 if (ret < 0) {
  101.                         dev_err(&udev->dev, "failed to restore interface %d "
  102.                                 "altsetting %d (error=%d)\n",
  103.                                 desc->bInterfaceNumber,
  104.                                 desc->bAlternateSetting,
  105.                                 ret);
  106.                         goto re_enumerate;
  107.                 }
  108.         }
  109.  
  110. done:
  111.         return 0;
  112.  
  113. re_enumerate:
  114.         hub_port_logical_disconnect(parent_hub, port1);
  115.         return -ENODEV;
  116. }

其实重置就是将重置的设备重新初始化。这个函数一般通过usb_reset_device()调用。132行，设置usb_hub->busy_bits，表示设置正在重置或者resume；133-141行，重新初始化端点0并初始化端口；142行，清除usb_hub->busy_bits，表示初始化结束；144-145行，如果上面的端口初始化失败，那么跳转到re_enumerate标志处执行标志段，hub_port_logical_disconnect(parent_hub, port)设置逻辑的连接变化事件，然后khubd会重新枚举这个设备。

 

 

 

 

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