hub.c

linux core 函数例程

	return 0;
}

static void *hub_probe(struct usb_device *dev, unsigned int i,
		       const struct usb_device_id *id)
{
	struct usb_interface_descriptor *interface;
	struct usb_endpoint_descriptor *endpoint;
	struct usb_hub *hub;
	unsigned long flags;

	interface = &dev->actconfig->interface[i].altsetting[0];

	/* Some hubs have a subclass of 1, which AFAICT according to the */
	/*  specs is not defined, but it works */
	if ((interface->bInterfaceSubClass != 0) &&
	    (interface->bInterfaceSubClass != 1)) {
		err("invalid subclass (%d) for USB hub device #%d",
			interface->bInterfaceSubClass, dev->devnum);
		return NULL;
	}

	/* Multiple endpoints? What kind of mutant ninja-hub is this? */
	if (interface->bNumEndpoints != 1) {
		err("invalid bNumEndpoints (%d) for USB hub device #%d",
			interface->bNumEndpoints, dev->devnum);
		return NULL;
	}

	endpoint = &interface->endpoint[0];

	/* Output endpoint? Curiousier and curiousier.. */
	if (!(endpoint->bEndpointAddress & USB_DIR_IN)) {
		err("Device #%d is hub class, but has output endpoint?",
			dev->devnum);
		return NULL;
	}

	/* If it's not an interrupt endpoint, we'd better punt! */
	if ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
			!= USB_ENDPOINT_XFER_INT) {
		err("Device #%d is hub class, but endpoint is not interrupt?",
			dev->devnum);
		return NULL;
	}

	/* We found a hub */
	info("USB hub found at %s", dev->devpath);

	hub = kmalloc(sizeof(*hub), GFP_KERNEL);
	if (!hub) {
		err("couldn't kmalloc hub struct");
		return NULL;
	}

	memset(hub, 0, sizeof(*hub));

	INIT_LIST_HEAD(&hub->event_list);
	hub->dev = dev;
	init_MUTEX(&hub->khubd_sem);

	/* Record the new hub's existence */
	spin_lock_irqsave(&hub_event_lock, flags);
	INIT_LIST_HEAD(&hub->hub_list);
	list_add(&hub->hub_list, &hub_list);
	spin_unlock_irqrestore(&hub_event_lock, flags);

	if (usb_hub_configure(hub, endpoint) >= 0)
		return hub;

	err("hub configuration failed for device at %s", dev->devpath);

	/* free hub, but first clean up its list. */
	spin_lock_irqsave(&hub_event_lock, flags);

	/* Delete it and then reset it */
	list_del(&hub->event_list);
	INIT_LIST_HEAD(&hub->event_list);
	list_del(&hub->hub_list);
	INIT_LIST_HEAD(&hub->hub_list);

	spin_unlock_irqrestore(&hub_event_lock, flags);

	kfree(hub);

	return NULL;
}

static void hub_disconnect(struct usb_device *dev, void *ptr)
{
	struct usb_hub *hub = (struct usb_hub *)ptr;
	unsigned long flags;

	spin_lock_irqsave(&hub_event_lock, flags);

	/* Delete it and then reset it */
	list_del(&hub->event_list);
	INIT_LIST_HEAD(&hub->event_list);
	list_del(&hub->hub_list);
	INIT_LIST_HEAD(&hub->hub_list);

	spin_unlock_irqrestore(&hub_event_lock, flags);

	down(&hub->khubd_sem); /* Wait for khubd to leave this hub alone. */
	up(&hub->khubd_sem);

	/* assuming we used keventd, it must quiesce too */
	if (hub->tt.hub)
		flush_scheduled_tasks ();

	if (hub->urb) {
		usb_unlink_urb(hub->urb);
		usb_free_urb(hub->urb);
		hub->urb = NULL;
	}

	if (hub->descriptor) {
		kfree(hub->descriptor);
		hub->descriptor = NULL;
	}

	/* Free the memory */
	kfree(hub);
}

static int hub_ioctl(struct usb_device *hub, unsigned int code, void *user_data)
{
	/* assert ifno == 0 (part of hub spec) */
	switch (code) {
	case USBDEVFS_HUB_PORTINFO: {
		struct usbdevfs_hub_portinfo *info = user_data;
		unsigned long flags;
		int i;

		spin_lock_irqsave(&hub_event_lock, flags);
		if (hub->devnum <= 0)
			info->nports = 0;
		else {
			info->nports = hub->maxchild;
			for (i = 0; i < info->nports; i++) {
				if (hub->children[i] == NULL)
					info->port[i] = 0;
				else
					info->port[i] =
						hub->children[i]->devnum;
			}
		}
		spin_unlock_irqrestore(&hub_event_lock, flags);

		return info->nports + 1;
		}

	default:
		return -ENOSYS;
	}
}

static int usb_hub_reset(struct usb_hub *hub)
{
	struct usb_device *dev = hub->dev;
	int i;

	/* Disconnect any attached devices */
	for (i = 0; i < hub->descriptor->bNbrPorts; i++) {
		if (dev->children[i])
			usb_disconnect(&dev->children[i]);
	}

	/* Attempt to reset the hub */
	if (hub->urb)
		usb_unlink_urb(hub->urb);
	else
		return -1;

	if (usb_reset_device(dev))
		return -1;

	hub->urb->dev = dev;                                                    
	if (usb_submit_urb(hub->urb, GFP_KERNEL))
		return -1;

	usb_hub_power_on(hub);

	return 0;
}

static void usb_hub_disconnect(struct usb_device *dev)
{
	struct usb_device *parent = dev->parent;
	int i;

	/* Find the device pointer to disconnect */
	if (parent) {
		for (i = 0; i < parent->maxchild; i++) {
			if (parent->children[i] == dev) {
				usb_disconnect(&parent->children[i]);
				return;
			}
		}
	}

	err("cannot disconnect hub %s", dev->devpath);
}

static int usb_hub_port_status(struct usb_device *hub, int port,
			       u16 *status, u16 *change)
{
	struct usb_port_status *portsts;
	int ret = -ENOMEM;

	portsts = kmalloc(sizeof(*portsts), GFP_KERNEL);
	if (portsts) {
		ret = usb_get_port_status(hub, port + 1, portsts);
		if (ret < 0)
			err("%s(%s) failed (err = %d)", __FUNCTION__, hub->devpath, ret);
		else {
			*status = le16_to_cpu(portsts->wPortStatus);
			*change = le16_to_cpu(portsts->wPortChange); 
			dbg("port %d, portstatus %x, change %x, %s", port + 1,
				*status, *change, portspeed(*status));
			ret = 0;
		}
		kfree(portsts);
	}
	return ret;
}

#define HUB_RESET_TRIES		5
#define HUB_PROBE_TRIES		2
#define HUB_SHORT_RESET_TIME	10
#define HUB_LONG_RESET_TIME	200
#define HUB_RESET_TIMEOUT	500

/* return: -1 on error, 0 on success, 1 on disconnect.  */
static int usb_hub_port_wait_reset(struct usb_device *hub, int port,
				struct usb_device *dev, unsigned int delay)
{
	int delay_time, ret;
	u16 portstatus;
	u16 portchange;

	for (delay_time = 0;
			delay_time < HUB_RESET_TIMEOUT;
			delay_time += delay) {
		/* wait to give the device a chance to reset */
		wait_ms(delay);

		/* read and decode port status */
		ret = usb_hub_port_status(hub, port, &portstatus, &portchange);
		if (ret < 0) {
			return -1;
		}

		/* Device went away? */
		if (!(portstatus & USB_PORT_STAT_CONNECTION))
			return 1;

		/* bomb out completely if something weird happened */
		if ((portchange & USB_PORT_STAT_C_CONNECTION))
			return -1;

		/* if we`ve finished resetting, then break out of the loop */
		if (!(portstatus & USB_PORT_STAT_RESET) &&
		    (portstatus & USB_PORT_STAT_ENABLE)) {
			if (portstatus & USB_PORT_STAT_HIGH_SPEED)
				dev->speed = USB_SPEED_HIGH;
			else if (portstatus & USB_PORT_STAT_LOW_SPEED)
				dev->speed = USB_SPEED_LOW;
			else
				dev->speed = USB_SPEED_FULL;
			return 0;
		}

		/* switch to the long delay after two short delay failures */
		if (delay_time >= 2 * HUB_SHORT_RESET_TIME)
			delay = HUB_LONG_RESET_TIME;

		dbg("port %d of hub %s not reset yet, waiting %dms", port + 1,
			hub->devpath, delay);
	}

	return -1;
}

/* return: -1 on error, 0 on success, 1 on disconnect.  */
static int usb_hub_port_reset(struct usb_device *hub, int port,
				struct usb_device *dev, unsigned int delay)
{
	int i, status;

	/* Reset the port */
	for (i = 0; i < HUB_RESET_TRIES; i++) {
		usb_set_port_feature(hub, port + 1, USB_PORT_FEAT_RESET);

		/* return on disconnect or reset */
		status = usb_hub_port_wait_reset(hub, port, dev, delay);
		if (status != -1) {
			usb_clear_port_feature(hub,
				port + 1, USB_PORT_FEAT_C_RESET);
			return status;
		}

		dbg("port %d of hub %s not enabled, trying reset again...",
			port + 1, hub->devpath);
		delay = HUB_LONG_RESET_TIME;
	}

	err("Cannot enable port %i of hub %s, disabling port.",
		port + 1, hub->devpath);
	err("Maybe the USB cable is bad?");

	return -1;
}

void usb_hub_port_disable(struct usb_device *hub, int port)
{
	int ret;

	ret = usb_clear_port_feature(hub, port + 1, USB_PORT_FEAT_ENABLE);
	if (ret)
		err("cannot disable port %d of hub %s (err = %d)",
			port + 1, hub->devpath, ret);
}

/* 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 which require longer delays of about 200-400ms.
 * Not covered by the spec - but easy to deal with.
 *
 * This implementation uses 400ms minimum debounce timeout and checks
 * every 100ms for transient disconnects to restart the delay.
 */

#define HUB_DEBOUNCE_TIMEOUT	400
#define HUB_DEBOUNCE_STEP	100

/* return: -1 on error, 0 on success, 1 on disconnect.  */
static int usb_hub_port_debounce(struct usb_device *hub, int port)
{
	int ret;
	unsigned delay_time;
	u16 portchange, portstatus;

	for (delay_time = 0; delay_time < HUB_DEBOUNCE_TIMEOUT; /* empty */ ) {

		/* wait debounce step increment */
		wait_ms(HUB_DEBOUNCE_STEP);

		ret = usb_hub_port_status(hub, port, &portstatus, &portchange);
		if (ret < 0)
			return -1;

		if ((portchange & USB_PORT_STAT_C_CONNECTION)) {
			usb_clear_port_feature(hub, port+1, USB_PORT_FEAT_C_CONNECTION);
			delay_time = 0;
		}
		else
			delay_time += HUB_DEBOUNCE_STEP;
	}
	return ((portstatus&USB_PORT_STAT_CONNECTION)) ? 0 : 1;
}

static void usb_hub_port_connect_change(struct usb_hub *hubstate, int port,
					u16 portstatus, u16 portchange)
{
	struct usb_device *hub = hubstate->dev;
	struct usb_device *dev;
	unsigned int delay = HUB_SHORT_RESET_TIME;
	int i;

	dbg("hub %s port %d, portstatus %x, change %x, %s",
		hub->devpath, port + 1,
		portstatus, portchange, portspeed (portstatus));

	/* Clear the connection change status */
	usb_clear_port_feature(hub, port + 1, USB_PORT_FEAT_C_CONNECTION);

	/* Disconnect any existing devices under this port */
	if (hub->children[port])
		usb_disconnect(&hub->children[port]);

	/* Return now if nothing is connected */
	if (!(portstatus & USB_PORT_STAT_CONNECTION)) {
		if (portstatus & USB_PORT_STAT_ENABLE)
			usb_hub_port_disable(hub, port);

		return;
	}

	if (usb_hub_port_debounce(hub, port)) {
		err("connect-debounce failed, port %d disabled", port+1);
		usb_hub_port_disable(hub, port);
		return;
	}

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

	down(&usb_address0_sem);

	for (i = 0; i < HUB_PROBE_TRIES; i++) {
		struct usb_device *pdev;
		int	len;

		/* Allocate a new device struct */
		dev = usb_alloc_dev(hub, hub->bus);
		if (!dev) {
			err("couldn't allocate usb_device");
			break;
		}

		hub->children[port] = dev;

		/* Reset the device, and detect its speed */
		if (usb_hub_port_reset(hub, port, dev, delay)) {
			usb_free_dev(dev);
			break;
		}