driver.c

linux 内核源代码

	/* For devices that don't have a driver, we do a generic suspend. */
	if (udev->dev.driver)
		udriver = to_usb_device_driver(udev->dev.driver);
	else {
		udev->do_remote_wakeup = 0;
		udriver = &usb_generic_driver;
	}
	status = udriver->suspend(udev, msg);

 done:
	dev_vdbg(&udev->dev, "%s: status %d\n", __FUNCTION__, status);
	if (status == 0)
		udev->dev.power.power_state.event = msg.event;
	return status;
}

/* Caller has locked udev's pm_mutex */
static int usb_resume_device(struct usb_device *udev)
{
	struct usb_device_driver	*udriver;
	int				status = 0;

	if (udev->state == USB_STATE_NOTATTACHED)
		goto done;
	if (udev->state != USB_STATE_SUSPENDED && !udev->reset_resume)
		goto done;

	/* Can't resume it if it doesn't have a driver. */
	if (udev->dev.driver == NULL) {
		status = -ENOTCONN;
		goto done;
	}

	if (udev->quirks & USB_QUIRK_RESET_RESUME)
		udev->reset_resume = 1;

	udriver = to_usb_device_driver(udev->dev.driver);
	status = udriver->resume(udev);

 done:
	dev_vdbg(&udev->dev, "%s: status %d\n", __FUNCTION__, status);
	if (status == 0) {
		udev->autoresume_disabled = 0;
		udev->dev.power.power_state.event = PM_EVENT_ON;
	}
	return status;
}

/* Caller has locked intf's usb_device's pm mutex */
static int usb_suspend_interface(struct usb_interface *intf, pm_message_t msg)
{
	struct usb_driver	*driver;
	int			status = 0;

	/* with no hardware, USB interfaces only use FREEZE and ON states */
	if (interface_to_usbdev(intf)->state == USB_STATE_NOTATTACHED ||
			!is_active(intf))
		goto done;

	if (intf->condition == USB_INTERFACE_UNBOUND)	/* This can't happen */
		goto done;
	driver = to_usb_driver(intf->dev.driver);

	if (driver->suspend && driver->resume) {
		status = driver->suspend(intf, msg);
		if (status == 0)
			mark_quiesced(intf);
		else if (!interface_to_usbdev(intf)->auto_pm)
			dev_err(&intf->dev, "%s error %d\n",
					"suspend", status);
	} else {
		// FIXME else if there's no suspend method, disconnect...
		// Not possible if auto_pm is set...
		dev_warn(&intf->dev, "no suspend for driver %s?\n",
				driver->name);
		mark_quiesced(intf);
	}

 done:
	dev_vdbg(&intf->dev, "%s: status %d\n", __FUNCTION__, status);
	return status;
}

/* Caller has locked intf's usb_device's pm_mutex */
static int usb_resume_interface(struct usb_interface *intf, int reset_resume)
{
	struct usb_driver	*driver;
	int			status = 0;

	if (interface_to_usbdev(intf)->state == USB_STATE_NOTATTACHED ||
			is_active(intf))
		goto done;

	/* Don't let autoresume interfere with unbinding */
	if (intf->condition == USB_INTERFACE_UNBINDING)
		goto done;

	/* Can't resume it if it doesn't have a driver. */
	if (intf->condition == USB_INTERFACE_UNBOUND) {
		status = -ENOTCONN;
		goto done;
	}
	driver = to_usb_driver(intf->dev.driver);

	if (reset_resume) {
		if (driver->reset_resume) {
			status = driver->reset_resume(intf);
			if (status)
				dev_err(&intf->dev, "%s error %d\n",
						"reset_resume", status);
		} else {
			// status = -EOPNOTSUPP;
			dev_warn(&intf->dev, "no %s for driver %s?\n",
					"reset_resume", driver->name);
		}
	} else {
		if (driver->resume) {
			status = driver->resume(intf);
			if (status)
				dev_err(&intf->dev, "%s error %d\n",
						"resume", status);
		} else {
			// status = -EOPNOTSUPP;
			dev_warn(&intf->dev, "no %s for driver %s?\n",
					"resume", driver->name);
		}
	}

done:
	dev_vdbg(&intf->dev, "%s: status %d\n", __FUNCTION__, status);
	if (status == 0)
		mark_active(intf);

	/* FIXME: Unbind the driver and reprobe if the resume failed
	 * (not possible if auto_pm is set) */
	return status;
}

#ifdef	CONFIG_USB_SUSPEND

/* Internal routine to check whether we may autosuspend a device. */
static int autosuspend_check(struct usb_device *udev, int reschedule)
{
	int			i;
	struct usb_interface	*intf;
	unsigned long		suspend_time, j;

	/* For autosuspend, fail fast if anything is in use or autosuspend
	 * is disabled.  Also fail if any interfaces require remote wakeup
	 * but it isn't available.
	 */
	udev->do_remote_wakeup = device_may_wakeup(&udev->dev);
	if (udev->pm_usage_cnt > 0)
		return -EBUSY;
	if (udev->autosuspend_delay < 0 || udev->autosuspend_disabled)
		return -EPERM;

	suspend_time = udev->last_busy + udev->autosuspend_delay;
	if (udev->actconfig) {
		for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
			intf = udev->actconfig->interface[i];
			if (!is_active(intf))
				continue;
			if (intf->pm_usage_cnt > 0)
				return -EBUSY;
			if (intf->needs_remote_wakeup &&
					!udev->do_remote_wakeup) {
				dev_dbg(&udev->dev, "remote wakeup needed "
						"for autosuspend\n");
				return -EOPNOTSUPP;
			}

			/* Don't allow autosuspend if the device will need
			 * a reset-resume and any of its interface drivers
			 * doesn't include support.
			 */
			if (udev->quirks & USB_QUIRK_RESET_RESUME) {
				struct usb_driver *driver;

				driver = to_usb_driver(intf->dev.driver);
				if (!driver->reset_resume)
					return -EOPNOTSUPP;
			}
		}
	}

	/* If everything is okay but the device hasn't been idle for long
	 * enough, queue a delayed autosuspend request.  If the device
	 * _has_ been idle for long enough and the reschedule flag is set,
	 * likewise queue a delayed (1 second) autosuspend request.
	 */
	j = jiffies;
	if (time_before(j, suspend_time))
		reschedule = 1;
	else
		suspend_time = j + HZ;
	if (reschedule) {
		if (!timer_pending(&udev->autosuspend.timer)) {
			queue_delayed_work(ksuspend_usb_wq, &udev->autosuspend,
				round_jiffies_relative(suspend_time - j));
		}
		return -EAGAIN;
	}
	return 0;
}

#else

static inline int autosuspend_check(struct usb_device *udev, int reschedule)
{
	return 0;
}

#endif	/* CONFIG_USB_SUSPEND */

/**
 * usb_suspend_both - suspend a USB device and its interfaces
 * @udev: the usb_device to suspend
 * @msg: Power Management message describing this state transition
 *
 * This is the central routine for suspending USB devices.  It calls the
 * suspend methods for all the interface drivers in @udev and then calls
 * the suspend method for @udev itself.  If an error occurs at any stage,
 * all the interfaces which were suspended are resumed so that they remain
 * in the same state as the device.
 *
 * If an autosuspend is in progress (@udev->auto_pm is set), the routine
 * checks first to make sure that neither the device itself or any of its
 * active interfaces is in use (pm_usage_cnt is greater than 0).  If they
 * are, the autosuspend fails.
 *
 * If the suspend succeeds, the routine recursively queues an autosuspend
 * request for @udev's parent device, thereby propagating the change up
 * the device tree.  If all of the parent's children are now suspended,
 * the parent will autosuspend in turn.
 *
 * The suspend method calls are subject to mutual exclusion under control
 * of @udev's pm_mutex.  Many of these calls are also under the protection
 * of @udev's device lock (including all requests originating outside the
 * USB subsystem), but autosuspend requests generated by a child device or
 * interface driver may not be.  Usbcore will insure that the method calls
 * do not arrive during bind, unbind, or reset operations.  However, drivers
 * must be prepared to handle suspend calls arriving at unpredictable times.
 * The only way to block such calls is to do an autoresume (preventing
 * autosuspends) while holding @udev's device lock (preventing outside
 * suspends).
 *
 * The caller must hold @udev->pm_mutex.
 *
 * This routine can run only in process context.
 */
static int usb_suspend_both(struct usb_device *udev, pm_message_t msg)
{
	int			status = 0;
	int			i = 0;
	struct usb_interface	*intf;
	struct usb_device	*parent = udev->parent;

	if (udev->state == USB_STATE_NOTATTACHED ||
			udev->state == USB_STATE_SUSPENDED)
		goto done;

	udev->do_remote_wakeup = device_may_wakeup(&udev->dev);

	if (udev->auto_pm) {
		status = autosuspend_check(udev, 0);
		if (status < 0)
			goto done;
	}

	/* Suspend all the interfaces and then udev itself */
	if (udev->actconfig) {
		for (; i < udev->actconfig->desc.bNumInterfaces; i++) {
			intf = udev->actconfig->interface[i];
			status = usb_suspend_interface(intf, msg);
			if (status != 0)
				break;
		}
	}
	if (status == 0)
		status = usb_suspend_device(udev, msg);

	/* If the suspend failed, resume interfaces that did get suspended */
	if (status != 0) {
		while (--i >= 0) {
			intf = udev->actconfig->interface[i];
			usb_resume_interface(intf, 0);
		}

		/* Try another autosuspend when the interfaces aren't busy */
		if (udev->auto_pm)
			autosuspend_check(udev, status == -EBUSY);

	/* If the suspend succeeded then prevent any more URB submissions,
	 * flush any outstanding URBs, and propagate the suspend up the tree.
	 */
	} else {
		cancel_delayed_work(&udev->autosuspend);
		udev->can_submit = 0;
		for (i = 0; i < 16; ++i) {
			usb_hcd_flush_endpoint(udev, udev->ep_out[i]);
			usb_hcd_flush_endpoint(udev, udev->ep_in[i]);
		}

		/* If this is just a FREEZE or a PRETHAW, udev might
		 * not really be suspended.  Only true suspends get
		 * propagated up the device tree.
		 */
		if (parent && udev->state == USB_STATE_SUSPENDED)
			usb_autosuspend_device(parent);
	}

 done:
	dev_vdbg(&udev->dev, "%s: status %d\n", __FUNCTION__, status);
	return status;
}

/**
 * usb_resume_both - resume a USB device and its interfaces
 * @udev: the usb_device to resume
 *
 * This is the central routine for resuming USB devices.  It calls the
 * the resume method for @udev and then calls the resume methods for all
 * the interface drivers in @udev.
 *
 * Before starting the resume, the routine calls itself recursively for
 * the parent device of @udev, thereby propagating the change up the device
 * tree and assuring that @udev will be able to resume.  If the parent is
 * unable to resume successfully, the routine fails.
 *
 * The resume method calls are subject to mutual exclusion under control
 * of @udev's pm_mutex.  Many of these calls are also under the protection
 * of @udev's device lock (including all requests originating outside the
 * USB subsystem), but autoresume requests generated by a child device or
 * interface driver may not be.  Usbcore will insure that the method calls
 * do not arrive during bind, unbind, or reset operations.  However, drivers
 * must be prepared to handle resume calls arriving at unpredictable times.
 * The only way to block such calls is to do an autoresume (preventing
 * other autoresumes) while holding @udev's device lock (preventing outside
 * resumes).
 *
 * The caller must hold @udev->pm_mutex.
 *
 * This routine can run only in process context.
 */
static int usb_resume_both(struct usb_device *udev)
{
	int			status = 0;
	int			i;
	struct usb_interface	*intf;
	struct usb_device	*parent = udev->parent;

	cancel_delayed_work(&udev->autosuspend);
	if (udev->state == USB_STATE_NOTATTACHED) {
		status = -ENODEV;
		goto done;
	}
	udev->can_submit = 1;

	/* Propagate the resume up the tree, if necessary */
	if (udev->state == USB_STATE_SUSPENDED) {
		if (udev->auto_pm && udev->autoresume_disabled) {
			status = -EPERM;
			goto done;
		}
		if (parent) {
			status = usb_autoresume_device(parent);
			if (status == 0) {
				status = usb_resume_device(udev);
				if (status || udev->state ==
						USB_STATE_NOTATTACHED) {
					usb_autosuspend_device(parent);

					/* It's possible usb_resume_device()
					 * failed after the port was
					 * unsuspended, causing udev to be
					 * logically disconnected.  We don't
					 * want usb_disconnect() to autosuspend
					 * the parent again, so tell it that
					 * udev disconnected while still
					 * suspended. */
					if (udev->state ==
							USB_STATE_NOTATTACHED)
						udev->discon_suspended = 1;
				}
			}
		} else {

			/* We can't progagate beyond the USB subsystem,
			 * so if a root hub's controller is suspended
			 * then we're stuck. */