hub.c

linux 内核源代码

 * USB resume explicitly guarantees that the power session between
 * the host and the device is the same as it was when the device
 * suspended.
 *
 * If CONFIG_USB_PERSIST and @udev->reset_resume are both set then this
 * routine won't check that the port is still enabled.  Furthermore,
 * if @udev->reset_resume is set then finish_port_resume() above will
 * reset @udev.  The end result is that a broken power session can be
 * recovered and @udev will appear to persist across a loss of VBUS power.
 *
 * For example, if a host controller doesn't maintain VBUS suspend current
 * during a system sleep or is reset when the system wakes up, all the USB
 * power sessions below it will be broken.  This is especially troublesome
 * for mass-storage devices containing mounted filesystems, since the
 * device will appear to have disconnected and all the memory mappings
 * to it will be lost.  Using the USB_PERSIST facility, the device can be
 * made to appear as if it had not disconnected.
 *
 * This facility is inherently dangerous.  Although usb_reset_device()
 * makes every effort to insure that the same device is present after the
 * reset as before, it cannot provide a 100% guarantee.  Furthermore it's
 * quite possible for a device to remain unaltered but its media to be
 * changed.  If the user replaces a flash memory card while the system is
 * asleep, he will have only himself to blame when the filesystem on the
 * new card is corrupted and the system crashes.
 *
 * Returns 0 on success, else negative errno.
 */
int usb_port_resume(struct usb_device *udev)
{
	struct usb_hub	*hub = hdev_to_hub(udev->parent);
	int		port1 = udev->portnum;
	int		status;
	u16		portchange, portstatus;
	unsigned	mask_flags, want_flags;

	/* Skip the initial Clear-Suspend step for a remote wakeup */
	status = hub_port_status(hub, port1, &portstatus, &portchange);
	if (status == 0 && !(portstatus & USB_PORT_STAT_SUSPEND))
		goto SuspendCleared;

	// dev_dbg(hub->intfdev, "resume port %d\n", port1);

	set_bit(port1, hub->busy_bits);

	/* see 7.1.7.7; affects power usage, but not budgeting */
	status = clear_port_feature(hub->hdev,
			port1, USB_PORT_FEAT_SUSPEND);
	if (status) {
		dev_dbg(hub->intfdev, "can't resume port %d, status %d\n",
				port1, status);
	} else {
		/* drive resume for at least 20 msec */
		dev_dbg(&udev->dev, "usb %sresume\n",
				udev->auto_pm ? "auto-" : "");
		msleep(25);

		/* Virtual root hubs can trigger on GET_PORT_STATUS to
		 * stop resume signaling.  Then finish the resume
		 * sequence.
		 */
		status = hub_port_status(hub, port1, &portstatus, &portchange);

 SuspendCleared:
		if (USB_PERSIST && udev->reset_resume)
			want_flags = USB_PORT_STAT_POWER
					| USB_PORT_STAT_CONNECTION;
		else
			want_flags = USB_PORT_STAT_POWER
					| USB_PORT_STAT_CONNECTION
					| USB_PORT_STAT_ENABLE;
		mask_flags = want_flags | USB_PORT_STAT_SUSPEND;

		if (status < 0 || (portstatus & mask_flags) != want_flags) {
			dev_dbg(hub->intfdev,
				"port %d status %04x.%04x after resume, %d\n",
				port1, portchange, portstatus, status);
			if (status >= 0)
				status = -ENODEV;
		} else {
			if (portchange & USB_PORT_STAT_C_SUSPEND)
				clear_port_feature(hub->hdev, port1,
						USB_PORT_FEAT_C_SUSPEND);
			/* TRSMRCY = 10 msec */
			msleep(10);
		}
	}

	clear_bit(port1, hub->busy_bits);
	if (!hub->hdev->parent && !hub->busy_bits[0])
		usb_enable_root_hub_irq(hub->hdev->bus);

	if (status == 0)
		status = finish_port_resume(udev);
	if (status < 0) {
		dev_dbg(&udev->dev, "can't resume, status %d\n", status);
		hub_port_logical_disconnect(hub, port1);
	}
	return status;
}

static int remote_wakeup(struct usb_device *udev)
{
	int	status = 0;

	usb_lock_device(udev);
	if (udev->state == USB_STATE_SUSPENDED) {
		dev_dbg(&udev->dev, "usb %sresume\n", "wakeup-");
		usb_mark_last_busy(udev);
		status = usb_external_resume_device(udev);
	}
	usb_unlock_device(udev);
	return status;
}

#else	/* CONFIG_USB_SUSPEND */

/* When CONFIG_USB_SUSPEND isn't set, we never suspend or resume any ports. */

int usb_port_suspend(struct usb_device *udev)
{
	return 0;
}

int usb_port_resume(struct usb_device *udev)
{
	int status = 0;

	/* However we may need to do a reset-resume */
	if (udev->reset_resume) {
		dev_dbg(&udev->dev, "reset-resume\n");
		status = usb_reset_device(udev);
	}
	return status;
}

static inline int remote_wakeup(struct usb_device *udev)
{
	return 0;
}

#endif

static int hub_suspend(struct usb_interface *intf, pm_message_t msg)
{
	struct usb_hub		*hub = usb_get_intfdata (intf);
	struct usb_device	*hdev = hub->hdev;
	unsigned		port1;

	/* fail if children aren't already suspended */
	for (port1 = 1; port1 <= hdev->maxchild; port1++) {
		struct usb_device	*udev;

		udev = hdev->children [port1-1];
		if (udev && udev->can_submit) {
			if (!hdev->auto_pm)
				dev_dbg(&intf->dev, "port %d nyet suspended\n",
						port1);
			return -EBUSY;
		}
	}

	dev_dbg(&intf->dev, "%s\n", __FUNCTION__);

	/* stop khubd and related activity */
	hub_quiesce(hub);
	return 0;
}

static int hub_resume(struct usb_interface *intf)
{
	struct usb_hub		*hub = usb_get_intfdata (intf);

	dev_dbg(&intf->dev, "%s\n", __FUNCTION__);

	/* tell khubd to look for changes on this hub */
	hub_activate(hub);
	return 0;
}

static int hub_reset_resume(struct usb_interface *intf)
{
	struct usb_hub *hub = usb_get_intfdata(intf);
	struct usb_device *hdev = hub->hdev;
	int port1;

	hub_power_on(hub);

	for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
		struct usb_device *child = hdev->children[port1-1];

		if (child) {

			/* For "USB_PERSIST"-enabled children we must
			 * mark the child device for reset-resume and
			 * turn off the connect-change status to prevent
			 * khubd from disconnecting it later.
			 */
			if (USB_PERSIST && child->persist_enabled) {
				child->reset_resume = 1;
				clear_port_feature(hdev, port1,
						USB_PORT_FEAT_C_CONNECTION);

			/* Otherwise we must disconnect the child,
			 * but as we may not lock the child device here
			 * we have to do a "logical" disconnect.
			 */
			} else {
				hub_port_logical_disconnect(hub, port1);
			}
		}
	}

	hub_activate(hub);
	return 0;
}

/**
 * usb_root_hub_lost_power - called by HCD if the root hub lost Vbus power
 * @rhdev: struct usb_device for the root hub
 *
 * The USB host controller driver calls this function when its root hub
 * is resumed and Vbus power has been interrupted or the controller
 * has been reset.  The routine marks @rhdev as having lost power.  When
 * the hub driver is resumed it will take notice; if CONFIG_USB_PERSIST
 * is enabled then it will carry out power-session recovery, otherwise
 * it will disconnect all the child devices.
 */
void usb_root_hub_lost_power(struct usb_device *rhdev)
{
	dev_warn(&rhdev->dev, "root hub lost power or was reset\n");
	rhdev->reset_resume = 1;
}
EXPORT_SYMBOL_GPL(usb_root_hub_lost_power);

#else	/* CONFIG_PM */

static inline int remote_wakeup(struct usb_device *udev)
{
	return 0;
}

#define hub_suspend		NULL
#define hub_resume		NULL
#define hub_reset_resume	NULL
#endif


/* USB 2.0 spec, 7.1.7.3 / fig 7-29:
 *
 * Between connect detection and reset signaling there must be a delay
 * of 100ms at least for debounce and power-settling.  The corresponding
 * timer shall restart whenever the downstream port detects a disconnect.
 * 
 * Apparently there are some bluetooth and irda-dongles and a number of
 * low-speed devices for which this debounce period may last over a second.
 * Not covered by the spec - but easy to deal with.
 *
 * This implementation uses a 1500ms total debounce timeout; if the
 * connection isn't stable by then it returns -ETIMEDOUT.  It checks
 * every 25ms for transient disconnects.  When the port status has been
 * unchanged for 100ms it returns the port status.
 */

#define HUB_DEBOUNCE_TIMEOUT	1500
#define HUB_DEBOUNCE_STEP	  25
#define HUB_DEBOUNCE_STABLE	 100

static int hub_port_debounce(struct usb_hub *hub, int port1)
{
	int ret;
	int total_time, stable_time = 0;
	u16 portchange, portstatus;
	unsigned connection = 0xffff;

	for (total_time = 0; ; total_time += HUB_DEBOUNCE_STEP) {
		ret = hub_port_status(hub, port1, &portstatus, &portchange);
		if (ret < 0)
			return ret;

		if (!(portchange & USB_PORT_STAT_C_CONNECTION) &&
		     (portstatus & USB_PORT_STAT_CONNECTION) == connection) {
			stable_time += HUB_DEBOUNCE_STEP;
			if (stable_time >= HUB_DEBOUNCE_STABLE)
				break;
		} else {
			stable_time = 0;
			connection = portstatus & USB_PORT_STAT_CONNECTION;
		}

		if (portchange & USB_PORT_STAT_C_CONNECTION) {
			clear_port_feature(hub->hdev, port1,
					USB_PORT_FEAT_C_CONNECTION);
		}

		if (total_time >= HUB_DEBOUNCE_TIMEOUT)
			break;
		msleep(HUB_DEBOUNCE_STEP);
	}

	dev_dbg (hub->intfdev,
		"debounce: port %d: total %dms stable %dms status 0x%x\n",
		port1, total_time, stable_time, portstatus);

	if (stable_time < HUB_DEBOUNCE_STABLE)
		return -ETIMEDOUT;
	return portstatus;
}

static void ep0_reinit(struct usb_device *udev)
{
	usb_disable_endpoint(udev, 0 + USB_DIR_IN);
	usb_disable_endpoint(udev, 0 + USB_DIR_OUT);
	usb_enable_endpoint(udev, &udev->ep0);
}

#define usb_sndaddr0pipe()	(PIPE_CONTROL << 30)
#define usb_rcvaddr0pipe()	((PIPE_CONTROL << 30) | USB_DIR_IN)

static int hub_set_address(struct usb_device *udev, int devnum)
{
	int retval;

	if (devnum <= 1)
		return -EINVAL;
	if (udev->state == USB_STATE_ADDRESS)
		return 0;
	if (udev->state != USB_STATE_DEFAULT)
		return -EINVAL;
	retval = usb_control_msg(udev, usb_sndaddr0pipe(),
		USB_REQ_SET_ADDRESS, 0, devnum, 0,
		NULL, 0, USB_CTRL_SET_TIMEOUT);
	if (retval == 0) {
		udev->devnum = devnum;	/* Device now using proper address */
		usb_set_device_state(udev, USB_STATE_ADDRESS);
		ep0_reinit(udev);
	}
	return retval;
}

/* Reset device, (re)assign address, get device descriptor.
 * Device connection must be stable, no more debouncing needed.
 * Returns device in USB_STATE_ADDRESS, except on error.
 *
 * If this is called for an already-existing device (as part of
 * usb_reset_device), the caller must own the device lock.  For a
 * newly detected device that is not accessible through any global
 * pointers, it's not necessary to lock the device.
 */
static int
hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
		int retry_counter)
{
	static DEFINE_MUTEX(usb_address0_mutex);

	struct usb_device	*hdev = hub->hdev;
	int			i, j, retval;
	unsigned		delay = HUB_SHORT_RESET_TIME;
	enum usb_device_speed	oldspeed = udev->speed;
	char 			*speed, *type;
	int			devnum = udev->devnum;

	/* root hub ports have a slightly longer reset period
	 * (from USB 2.0 spec, section 7.1.7.5)
	 */
	if (!hdev->parent) {
		delay = HUB_ROOT_RESET_TIME;
		if (port1 == hdev->bus->otg_port)
			hdev->bus->b_hnp_enable = 0;
	}

	/* Some low speed devices have problems with the quick delay, so */
	/*  be a bit pessimistic with those devices. RHbug #23670 */
	if (oldspeed == USB_SPEED_LOW)
		delay = HUB_LONG_RESET_TIME;

	mutex_lock(&usb_address0_mutex);

	/* Reset the device; full speed may morph to high speed */
	retval = hub_port_reset(hub, port1, udev, delay);
	if (retval < 0)		/* error or disconnect */
		goto fail;
				/* success, speed is known */
	retval = -ENODEV;

	if (oldspeed != USB_SPEED_UNKNOWN && oldspeed != udev->speed) {
		dev_dbg(&udev->dev, "device reset changed speed!\n");
		goto fail;
	}
	oldspeed = udev->speed;

	/* USB 2.0 section 5.5.3 talks about ep0 maxpacket ...
	 * it's fixed size except for full speed devices.
	 * For Wireless USB devices, ep0 max packet is always 512 (tho
	 * reported as 0xff in the device descriptor). WUSB1.0[4.8.1].
	 */
	switch (udev->speed) {
	case USB_SPEED_VARIABLE:	/* fixed at 512 */
		udev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(512);
		break;
	case USB_SPEED_HIGH:		/* fixed at 64 */
		udev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(64);
		break;
	case USB_SPEED_FULL:		/* 8, 16, 32, or 64 */
		/* to determine the ep0 maxpacket size, try to read
		 * the device descriptor to get bMaxPacketSize0 and
		 * then correct our initial guess.
		 */
		udev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(64);
		break;
	case USB_SPEED_LOW:		/* fixed at 8 */
		udev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(8);
		break;
	default:
		goto fail;
	}
 
	type = "";
	switch (udev->speed) {
	case USB_SPEED_LOW:	speed = "low";	break;
	case USB_SPEED_FULL:	speed = "full";	break;
	case USB_SPEED_HIGH:	speed = "high";	break;
	case USB_SPEED_VARIABLE:
				speed = "variable";
				type = "Wireless ";
				break;
	default: 		speed = "?";	break;
	}
	dev_info (&udev->dev,
		  "%s %s speed %sUSB device using %s and address %d\n",
		  (udev->config) ? "reset" : "new", speed, type,
		  udev->bus->controller->driver->name, devnum);

	/* Set up TT records, if needed  */
	if (hdev->tt) {
		udev->tt = hdev->tt;
		udev->ttport = hdev->ttport;
	} else if (udev->speed != USB_SPEED_HIGH
			&& hdev->speed == USB_SPEED_HIGH) {
		udev->tt = &hub->tt;
		udev->ttport = port1;
	}
 
	/* Why interleave GET_DESCRIPTOR and SET_ADDRESS this way?
	 * Because device hardware and firmware is sometimes buggy in
	 * this area, and this is how Linux has done it for ages.
	 * Change it cautiously.
	 *
	 * NOTE:  If USE_NEW_SCHEME() is true we will start by issuing
	 * a 64-byte GET_DESCRIPTOR request.  This is what Windows does,
	 * so it may help with some non-standards-compliant devices.
	 * Otherwise we start with SET_ADDRESS and then try to read the
	 * first 8 bytes of the device descript