hub.c

linux core 函数例程

		/* Find a new address for it */
		usb_connect(dev);

		/* Set up TT records, if needed  */
		if (hub->tt) {
			dev->tt = hub->tt;
			dev->ttport = hub->ttport;
		} else if (dev->speed != USB_SPEED_HIGH
				&& hub->speed == USB_SPEED_HIGH) {
			dev->tt = &hubstate->tt;
			dev->ttport = port + 1;
		}

		/* Save readable and stable topology id, distinguishing
		 * devices by location for diagnostics, tools, etc.  The
		 * string is a path along hub ports, from the root.  Each
		 * device's id will be stable until USB is re-cabled, and
		 * hubs are often labeled with these port numbers.
		 *
		 * Initial size: ".NN" times five hubs + NUL = 16 bytes max
		 * (quite rare, since most hubs have 4-6 ports).
		 */
		pdev = dev->parent;
		if (pdev->devpath [0] != '/')	/* parent not root */
			len = snprintf (dev->devpath, sizeof dev->devpath,
				"%s.%d", pdev->devpath, port + 1);
		else	/* root == "/", root port 2 == "2", port 3 that hub "/2.3" */
			len = snprintf (dev->devpath, sizeof dev->devpath,
				"%d", port + 1);
		if (len == sizeof dev->devpath)
			warn ("devpath size! usb/%03d/%03d path %s",
				dev->bus->busnum, dev->devnum, dev->devpath);
		info("new USB device %s-%s, assigned address %d",
			dev->bus->bus_name, dev->devpath, dev->devnum);

		/* put the device in the global device tree */
		dev->dev.parent = &dev->parent->dev;
		sprintf (&dev->dev.name[0], "USB device %04x:%04x",
			 dev->descriptor.idVendor,
			 dev->descriptor.idProduct);
		/* find the number of the port this device is connected to */
		sprintf (&dev->dev.bus_id[0], "unknown_port_%03d", dev->devnum);
		for (i = 0; i < USB_MAXCHILDREN; ++i) {
			if (dev->parent->children[i] == dev) {
				sprintf (&dev->dev.bus_id[0], "%02d", i);
				break;
			}
		}

		/* Run it through the hoops (find a driver, etc) */
		if (!usb_new_device(dev))
			goto done;

		/* Free the configuration if there was an error */
		usb_free_dev(dev);

		/* Switch to a long reset time */
		delay = HUB_LONG_RESET_TIME;
	}

	hub->children[port] = NULL;
	usb_hub_port_disable(hub, port);
done:
	up(&usb_address0_sem);
}

static void usb_hub_events(void)
{
	unsigned long flags;
	struct list_head *tmp;
	struct usb_device *dev;
	struct usb_hub *hub;
	struct usb_hub_status hubsts;
	u16 hubstatus;
	u16 hubchange;
	u16 portstatus;
	u16 portchange;
	int i, ret;

	/*
	 *  We restart the list everytime to avoid a deadlock with
	 * deleting hubs downstream from this one. This should be
	 * safe since we delete the hub from the event list.
	 * Not the most efficient, but avoids deadlocks.
	 */
	while (1) {
		spin_lock_irqsave(&hub_event_lock, flags);

		if (list_empty(&hub_event_list))
			break;

		/* Grab the next entry from the beginning of the list */
		tmp = hub_event_list.next;

		hub = list_entry(tmp, struct usb_hub, event_list);
		dev = hub->dev;

		list_del(tmp);
		INIT_LIST_HEAD(tmp);

		down(&hub->khubd_sem); /* never blocks, we were on list */
		spin_unlock_irqrestore(&hub_event_lock, flags);

		if (hub->error) {
			dbg("resetting hub %s for error %d",
				dev->devpath, hub->error);

			if (usb_hub_reset(hub)) {
				err("error resetting hub %s - disconnecting",
					dev->devpath);
				up(&hub->khubd_sem);
				usb_hub_disconnect(dev);
				continue;
			}

			hub->nerrors = 0;
			hub->error = 0;
		}

		for (i = 0; i < hub->descriptor->bNbrPorts; i++) {
			ret = usb_hub_port_status(dev, i, &portstatus, &portchange);
			if (ret < 0) {
				continue;
			}

			if (portchange & USB_PORT_STAT_C_CONNECTION) {
				dbg("hub %s port %d connection change",
					dev->devpath, i + 1);
				usb_hub_port_connect_change(hub, i, portstatus, portchange);
			} else if (portchange & USB_PORT_STAT_C_ENABLE) {
				dbg("hub %s port %d enable change, status %x",
					dev->devpath, i + 1, portstatus);
				usb_clear_port_feature(dev,
					i + 1, USB_PORT_FEAT_C_ENABLE);

				/*
				 * EM interference sometimes causes badly
				 * shielded USB devices to be shutdown by
				 * the hub, this hack enables them again.
				 * Works at least with mouse driver. 
				 */
				if (!(portstatus & USB_PORT_STAT_ENABLE)
				    && (portstatus & USB_PORT_STAT_CONNECTION)
				    && (dev->children[i])) {
					err("already running hub %s port %i "
					    "disabled by hub (EMI?), "
					    "re-enabling...",
						dev->devpath, i + 1);
					usb_hub_port_connect_change(hub,
						i, portstatus, portchange);
				}
			}

			if (portchange & USB_PORT_STAT_C_SUSPEND) {
				dbg("hub %s port %d suspend change",
					dev->devpath, i + 1);
				usb_clear_port_feature(dev,
					i + 1,  USB_PORT_FEAT_C_SUSPEND);
			}
			
			if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
				err("hub %s port %d over-current change",
					dev->devpath, i + 1);
				usb_clear_port_feature(dev,
					i + 1, USB_PORT_FEAT_C_OVER_CURRENT);
				usb_hub_power_on(hub);
			}

			if (portchange & USB_PORT_STAT_C_RESET) {
				dbg("hub %s port %d reset change",
					dev->devpath, i + 1);
				usb_clear_port_feature(dev,
					i + 1, USB_PORT_FEAT_C_RESET);
			}
		} /* end for i */

		/* deal with hub status changes */
		if (usb_get_hub_status(dev, &hubsts) < 0)
			err("get_hub_status %s failed", dev->devpath);
		else {
			hubstatus = le16_to_cpup(&hubsts.wHubStatus);
			hubchange = le16_to_cpup(&hubsts.wHubChange);
			if (hubchange & HUB_CHANGE_LOCAL_POWER) {
				dbg("hub %s power change", dev->devpath);
				usb_clear_hub_feature(dev, C_HUB_LOCAL_POWER);
			}
			if (hubchange & HUB_CHANGE_OVERCURRENT) {
				dbg("hub %s overcurrent change", dev->devpath);
				wait_ms(500);	/* Cool down */
				usb_clear_hub_feature(dev, C_HUB_OVER_CURRENT);
                        	usb_hub_power_on(hub);
			}
		}
		up(&hub->khubd_sem);
        } /* end while (1) */

	spin_unlock_irqrestore(&hub_event_lock, flags);
}

static int usb_hub_thread(void *__hub)
{
	lock_kernel();

	/*
	 * This thread doesn't need any user-level access,
	 * so get rid of all our resources
	 */

	daemonize();

	/* Setup a nice name */
	strcpy(current->comm, "khubd");

	/* Send me a signal to get me die (for debugging) */
	do {
		usb_hub_events();
		if (current->flags & PF_FREEZE)
			refrigerator(PF_IOTHREAD);
		wait_event_interruptible(khubd_wait, !list_empty(&hub_event_list)); 
	} while (!signal_pending(current));

	dbg("usb_hub_thread exiting");

	unlock_kernel();
	complete_and_exit(&khubd_exited, 0);
}

static struct usb_device_id hub_id_table [] = {
    { match_flags: USB_DEVICE_ID_MATCH_DEV_CLASS,
      bDeviceClass: USB_CLASS_HUB},
    { match_flags: USB_DEVICE_ID_MATCH_INT_CLASS,
      bInterfaceClass: USB_CLASS_HUB},
    { }						/* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, hub_id_table);

static struct usb_driver hub_driver = {
	name:		"hub",
	probe:		hub_probe,
	ioctl:		hub_ioctl,
	disconnect:	hub_disconnect,
	id_table:	hub_id_table,
};

/*
 * This should be a separate module.
 */
int usb_hub_init(void)
{
	int pid;

	if (usb_register(&hub_driver) < 0) {
		err("Unable to register USB hub driver");
		return -1;
	}

	pid = kernel_thread(usb_hub_thread, NULL,
		CLONE_FS | CLONE_FILES | CLONE_SIGHAND);
	if (pid >= 0) {
		khubd_pid = pid;

		return 0;
	}

	/* Fall through if kernel_thread failed */
	usb_deregister(&hub_driver);
	err("failed to start usb_hub_thread");

	return -1;
}

void usb_hub_cleanup(void)
{
	int ret;

	/* Kill the thread */
	ret = kill_proc(khubd_pid, SIGTERM, 1);

	wait_for_completion(&khubd_exited);

	/*
	 * Hub resources are freed for us by usb_deregister. It calls
	 * usb_driver_purge on every device which in turn calls that
	 * devices disconnect function if it is using this driver.
	 * The hub_disconnect function takes care of releasing the
	 * individual hub resources. -greg
	 */
	usb_deregister(&hub_driver);
} /* usb_hub_cleanup() */

/*
 * WARNING - If a driver calls usb_reset_device, you should simulate a
 * disconnect() and probe() for other interfaces you doesn't claim. This
 * is left up to the driver writer right now. This insures other drivers
 * have a chance to re-setup their interface.
 *
 * Take a look at proc_resetdevice in devio.c for some sample code to
 * do this.
 */
int usb_reset_device(struct usb_device *dev)
{
	struct usb_device *parent = dev->parent;
	struct usb_device_descriptor descriptor;
	int i, ret, port = -1;

	if (!parent) {
		err("attempting to reset root hub!");
		return -EINVAL;
	}

	for (i = 0; i < parent->maxchild; i++)
		if (parent->children[i] == dev) {
			port = i;
			break;
		}

	if (port < 0)
		return -ENOENT;

	down(&usb_address0_sem);

	/* Send a reset to the device */
	if (usb_hub_port_reset(parent, port, dev, HUB_SHORT_RESET_TIME)) {
		usb_hub_port_disable(parent, port);
		up(&usb_address0_sem);
		return(-ENODEV);
	}

	/* Reprogram the Address */
	ret = usb_set_address(dev);
	if (ret < 0) {
		err("USB device not accepting new address (error=%d)", ret);
		usb_hub_port_disable(parent, port);
		up(&usb_address0_sem);
		return ret;
	}

	/* Let the SET_ADDRESS settle */
	wait_ms(10);

	up(&usb_address0_sem);

	/*
	 * Now we fetch the configuration descriptors for the device and
	 * see if anything has changed. If it has, we dump the current
	 * parsed descriptors and reparse from scratch. Then we leave
	 * the device alone for the caller to finish setting up.
	 *
	 * If nothing changed, we reprogram the configuration and then
	 * the alternate settings.
	 */
	ret = usb_get_descriptor(dev, USB_DT_DEVICE, 0, &descriptor,
			sizeof(descriptor));
	if (ret < 0)
		return ret;

	le16_to_cpus(&descriptor.bcdUSB);
	le16_to_cpus(&descriptor.idVendor);
	le16_to_cpus(&descriptor.idProduct);
	le16_to_cpus(&descriptor.bcdDevice);

	if (memcmp(&dev->descriptor, &descriptor, sizeof(descriptor))) {
		usb_destroy_configuration(dev);

		ret = usb_get_device_descriptor(dev);
		if (ret < sizeof(dev->descriptor)) {
			if (ret < 0)
				err("unable to get device %s descriptor "
					"(error=%d)", dev->devpath, ret);
			else
				err("USB device %s descriptor short read "
					"(expected %Zi, got %i)",
					dev->devpath,
					sizeof(dev->descriptor), ret);
        
			clear_bit(dev->devnum, dev->bus->devmap.devicemap);
			dev->devnum = -1;
			return -EIO;
		}

		ret = usb_get_configuration(dev);
		if (ret < 0) {
			err("unable to get configuration (error=%d)", ret);
			usb_destroy_configuration(dev);
			clear_bit(dev->devnum, dev->bus->devmap.devicemap);
			dev->devnum = -1;
			return 1;
		}

		dev->actconfig = dev->config;
		usb_set_maxpacket(dev);

		return 1;
	}

	ret = usb_set_configuration(dev, dev->actconfig->bConfigurationValue);
	if (ret < 0) {
		err("failed to set dev %s active configuration (error=%d)",
			dev->devpath, ret);
		return ret;
	}

	for (i = 0; i < dev->actconfig->bNumInterfaces; i++) {
		struct usb_interface *intf = &dev->actconfig->interface[i];
		struct usb_interface_descriptor *as;

		as = &intf->altsetting[intf->act_altsetting];
		ret = usb_set_interface(dev, as->bInterfaceNumber,
			as->bAlternateSetting);
		if (ret < 0) {
			err("failed to set active alternate setting "
				"for dev %s interface %d (error=%d)",
				dev->devpath, i, ret);
			return ret;
		}
	}

	return 0;
}