message.c

h内核

void usb_disable_device(struct usb_device *dev, int skip_ep0)
{
	int i;

	dev_dbg(&dev->dev, "%s nuking %s URBs\n", __FUNCTION__,
			skip_ep0 ? "non-ep0" : "all");
	for (i = skip_ep0; i < 16; ++i) {
		usb_disable_endpoint(dev, i);
		usb_disable_endpoint(dev, i + USB_DIR_IN);
	}
	dev->toggle[0] = dev->toggle[1] = 0;

	/* getting rid of interfaces will disconnect
	 * any drivers bound to them (a key side effect)
	 */
	if (dev->actconfig) {
		for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++) {
			struct usb_interface	*interface;

			/* remove this interface */
			interface = dev->actconfig->interface[i];
			dev_dbg (&dev->dev, "unregistering interface %s\n",
				interface->dev.bus_id);
			usb_remove_sysfs_intf_files(interface);
			device_del (&interface->dev);
		}

		/* Now that the interfaces are unbound, nobody should
		 * try to access them.
		 */
		for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++) {
			put_device (&dev->actconfig->interface[i]->dev);
			dev->actconfig->interface[i] = NULL;
		}
		dev->actconfig = NULL;
		if (dev->state == USB_STATE_CONFIGURED)
			usb_set_device_state(dev, USB_STATE_ADDRESS);
	}
}


/*
 * usb_enable_endpoint - Enable an endpoint for USB communications
 * @dev: the device whose interface is being enabled
 * @ep: the endpoint
 *
 * Resets the endpoint toggle, and sets dev->ep_{in,out} pointers.
 * For control endpoints, both the input and output sides are handled.
 */
static void
usb_enable_endpoint(struct usb_device *dev, struct usb_host_endpoint *ep)
{
	unsigned int epaddr = ep->desc.bEndpointAddress;
	unsigned int epnum = epaddr & USB_ENDPOINT_NUMBER_MASK;
	int is_control;

	is_control = ((ep->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
			== USB_ENDPOINT_XFER_CONTROL);
	if (usb_endpoint_out(epaddr) || is_control) {
		usb_settoggle(dev, epnum, 1, 0);
		dev->ep_out[epnum] = ep;
	}
	if (!usb_endpoint_out(epaddr) || is_control) {
		usb_settoggle(dev, epnum, 0, 0);
		dev->ep_in[epnum] = ep;
	}
}

/*
 * usb_enable_interface - Enable all the endpoints for an interface
 * @dev: the device whose interface is being enabled
 * @intf: pointer to the interface descriptor
 *
 * Enables all the endpoints for the interface's current altsetting.
 */
void usb_enable_interface(struct usb_device *dev,
		struct usb_interface *intf)
{
	struct usb_host_interface *alt = intf->cur_altsetting;
	int i;

	for (i = 0; i < alt->desc.bNumEndpoints; ++i)
		usb_enable_endpoint(dev, &alt->endpoint[i]);
}

/**
 * usb_set_interface - Makes a particular alternate setting be current
 * @dev: the device whose interface is being updated
 * @interface: the interface being updated
 * @alternate: the setting being chosen.
 * Context: !in_interrupt ()
 *
 * This is used to enable data transfers on interfaces that may not
 * be enabled by default.  Not all devices support such configurability.
 * Only the driver bound to an interface may change its setting.
 *
 * Within any given configuration, each interface may have several
 * alternative settings.  These are often used to control levels of
 * bandwidth consumption.  For example, the default setting for a high
 * speed interrupt endpoint may not send more than 64 bytes per microframe,
 * while interrupt transfers of up to 3KBytes per microframe are legal.
 * Also, isochronous endpoints may never be part of an
 * interface's default setting.  To access such bandwidth, alternate
 * interface settings must be made current.
 *
 * Note that in the Linux USB subsystem, bandwidth associated with
 * an endpoint in a given alternate setting is not reserved until an URB
 * is submitted that needs that bandwidth.  Some other operating systems
 * allocate bandwidth early, when a configuration is chosen.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 * Also, drivers must not change altsettings while urbs are scheduled for
 * endpoints in that interface; all such urbs must first be completed
 * (perhaps forced by unlinking).
 *
 * Returns zero on success, or else the status code returned by the
 * underlying usb_control_msg() call.
 */
int usb_set_interface(struct usb_device *dev, int interface, int alternate)
{
	struct usb_interface *iface;
	struct usb_host_interface *alt;
	int ret;
	int manual = 0;

	if (dev->state == USB_STATE_SUSPENDED)
		return -EHOSTUNREACH;

	iface = usb_ifnum_to_if(dev, interface);
	if (!iface) {
		dev_dbg(&dev->dev, "selecting invalid interface %d\n",
			interface);
		return -EINVAL;
	}

	alt = usb_altnum_to_altsetting(iface, alternate);
	if (!alt) {
		warn("selecting invalid altsetting %d", alternate);
		return -EINVAL;
	}

	ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
				   USB_REQ_SET_INTERFACE, USB_RECIP_INTERFACE,
				   alternate, interface, NULL, 0, HZ * 5);

	/* 9.4.10 says devices don't need this and are free to STALL the
	 * request if the interface only has one alternate setting.
	 */
	if (ret == -EPIPE && iface->num_altsetting == 1) {
		dev_dbg(&dev->dev,
			"manual set_interface for iface %d, alt %d\n",
			interface, alternate);
		manual = 1;
	} else if (ret < 0)
		return ret;

	/* FIXME drivers shouldn't need to replicate/bugfix the logic here
	 * when they implement async or easily-killable versions of this or
	 * other "should-be-internal" functions (like clear_halt).
	 * should hcd+usbcore postprocess control requests?
	 */

	/* prevent submissions using previous endpoint settings */
	usb_disable_interface(dev, iface);

	iface->cur_altsetting = alt;

	/* If the interface only has one altsetting and the device didn't
	 * accept the request, we attempt to carry out the equivalent action
	 * by manually clearing the HALT feature for each endpoint in the
	 * new altsetting.
	 */
	if (manual) {
		int i;

		for (i = 0; i < alt->desc.bNumEndpoints; i++) {
			unsigned int epaddr =
				alt->endpoint[i].desc.bEndpointAddress;
			unsigned int pipe =
	__create_pipe(dev, USB_ENDPOINT_NUMBER_MASK & epaddr)
	| (usb_endpoint_out(epaddr) ? USB_DIR_OUT : USB_DIR_IN);

			usb_clear_halt(dev, pipe);
		}
	}

	/* 9.1.1.5: reset toggles for all endpoints in the new altsetting
	 *
	 * Note:
	 * Despite EP0 is always present in all interfaces/AS, the list of
	 * endpoints from the descriptor does not contain EP0. Due to its
	 * omnipresence one might expect EP0 being considered "affected" by
	 * any SetInterface request and hence assume toggles need to be reset.
	 * However, EP0 toggles are re-synced for every individual transfer
	 * during the SETUP stage - hence EP0 toggles are "don't care" here.
	 * (Likewise, EP0 never "halts" on well designed devices.)
	 */
	usb_enable_interface(dev, iface);

	return 0;
}

/**
 * usb_reset_configuration - lightweight device reset
 * @dev: the device whose configuration is being reset
 *
 * This issues a standard SET_CONFIGURATION request to the device using
 * the current configuration.  The effect is to reset most USB-related
 * state in the device, including interface altsettings (reset to zero),
 * endpoint halts (cleared), and data toggle (only for bulk and interrupt
 * endpoints).  Other usbcore state is unchanged, including bindings of
 * usb device drivers to interfaces.
 *
 * Because this affects multiple interfaces, avoid using this with composite
 * (multi-interface) devices.  Instead, the driver for each interface may
 * use usb_set_interface() on the interfaces it claims.  Resetting the whole
 * configuration would affect other drivers' interfaces.
 *
 * The caller must own the device lock.
 *
 * Returns zero on success, else a negative error code.
 */
int usb_reset_configuration(struct usb_device *dev)
{
	int			i, retval;
	struct usb_host_config	*config;

	if (dev->state == USB_STATE_SUSPENDED)
		return -EHOSTUNREACH;

	/* caller must have locked the device and must own
	 * the usb bus readlock (so driver bindings are stable);
	 * calls during probe() are fine
	 */

	for (i = 1; i < 16; ++i) {
		usb_disable_endpoint(dev, i);
		usb_disable_endpoint(dev, i + USB_DIR_IN);
	}

	config = dev->actconfig;
	retval = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
			USB_REQ_SET_CONFIGURATION, 0,
			config->desc.bConfigurationValue, 0,
			NULL, 0, HZ * USB_CTRL_SET_TIMEOUT);
	if (retval < 0) {
		usb_set_device_state(dev, USB_STATE_ADDRESS);
		return retval;
	}

	dev->toggle[0] = dev->toggle[1] = 0;

	/* re-init hc/hcd interface/endpoint state */
	for (i = 0; i < config->desc.bNumInterfaces; i++) {
		struct usb_interface *intf = config->interface[i];
		struct usb_host_interface *alt;

		alt = usb_altnum_to_altsetting(intf, 0);

		/* No altsetting 0?  We'll assume the first altsetting.
		 * We could use a GetInterface call, but if a device is
		 * so non-compliant that it doesn't have altsetting 0
		 * then I wouldn't trust its reply anyway.
		 */
		if (!alt)
			alt = &intf->altsetting[0];

		intf->cur_altsetting = alt;
		usb_enable_interface(dev, intf);
	}
	return 0;
}

static void release_interface(struct device *dev)
{
	struct usb_interface *intf = to_usb_interface(dev);
	struct usb_interface_cache *intfc =
			altsetting_to_usb_interface_cache(intf->altsetting);

	kref_put(&intfc->ref, usb_release_interface_cache);
	kfree(intf);
}

/*
 * usb_set_configuration - Makes a particular device setting be current
 * @dev: the device whose configuration is being updated
 * @configuration: the configuration being chosen.
 * Context: !in_interrupt(), caller owns the device lock
 *
 * This is used to enable non-default device modes.  Not all devices
 * use this kind of configurability; many devices only have one
 * configuration.
 *
 * USB device configurations may affect Linux interoperability,
 * power consumption and the functionality available.  For example,
 * the default configuration is limited to using 100mA of bus power,
 * so that when certain device functionality requires more power,
 * and the device is bus powered, that functionality should be in some
 * non-default device configuration.  Other device modes may also be
 * reflected as configuration options, such as whether two ISDN
 * channels are available independently; and choosing between open
 * standard device protocols (like CDC) or proprietary ones.
 *
 * Note that USB has an additional level of device configurability,
 * associated with interfaces.  That configurability is accessed using
 * usb_set_interface().
 *
 * This call is synchronous. The calling context must be able to sleep,
 * must own the device lock, and must not hold the driver model's USB
 * bus rwsem; usb device driver probe() methods cannot use this routine.
 *
 * Returns zero on success, or else the status code returned by the
 * underlying call that failed.  On succesful completion, each interface
 * in the original device configuration has been destroyed, and each one
 * in the new configuration has been probed by all relevant usb device
 * drivers currently known to the kernel.
 */
int usb_set_configuration(struct usb_device *dev, int configuration)
{
	int i, ret;
	struct usb_host_config *cp = NULL;
	struct usb_interface **new_interfaces = NULL;
	int n, nintf;

	for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
		if (dev->config[i].desc.bConfigurationValue == configuration) {
			cp = &dev->config[i];
			break;
		}
	}
	if ((!cp && configuration != 0))
		return -EINVAL;

	/* The USB spec says configuration 0 means unconfigured.
	 * But if a device includes a configuration numbered 0,
	 * we will accept it as a correctly configured state.
	 */
	if (cp && configuration == 0)
		dev_warn(&dev->dev, "config 0 descriptor??\n");

	if (dev->state == USB_STATE_SUSPENDED)
		return -EHOSTUNREACH;

	/* Allocate memory for new interfaces before doing anything else,
	 * so that if we run out then nothing will have changed. */
	n = nintf = 0;
	if (cp) {
		nintf = cp->desc.bNumInterfaces;
		new_interfaces = kmalloc(nintf * sizeof(*new_interfaces),
				GFP_KERNEL);
		if (!new_interfaces) {
			dev_err(&dev->dev, "Out of memory");
			return -ENOMEM;
		}

		for (; n < nintf; ++n) {
			new_interfaces[n] = kmalloc(
					sizeof(struct usb_interface),
					GFP_KERNEL);
			if (!new_interfaces[n]) {
				dev_err(&dev->dev, "Out of memory");
				ret = -ENOMEM;
free_interfaces:
				while (--n >= 0)
					kfree(new_interfaces[n]);
				kfree(new_interfaces);
				return ret;
			}
		}
	}

	/* if it's already configured, clear out old state first.
	 * getting rid of old interfaces means unbinding their drivers.
	 */
	if (dev->state != USB_STATE_ADDRESS)
		usb_disable_device (dev, 1);	// Skip ep0

	if ((ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
			USB_REQ_SET_CONFIGURATION, 0, configuration, 0,
			NULL, 0, HZ * USB_CTRL_SET_TIMEOUT)) < 0)
		goto free_interfaces;

	dev->actconfig = cp;
	if (!cp)
		usb_set_device_state(dev, USB_STATE_ADDRESS);
	else {
		usb_set_device_state(dev, USB_STATE_CONFIGURED);

		/* Initialize the new interface structures and the
		 * hc/hcd/usbcore interface/endpoint state.
		 */
		for (i = 0; i < nintf; ++i) {
			struct usb_interface_cache *intfc;
			struct usb_interface *intf;
			struct usb_host_interface *alt;

			cp->interface[i] = intf = new_interfaces[i];
			memset(intf, 0, sizeof(*intf));
			intfc = cp->intf_cache[i];
			intf->altsetting = intfc->altsetting;
			intf->num_altsetting = intfc->num_altsetting;
			kref_get(&intfc->ref);

			alt = usb_altnum_to_altsetting(intf, 0);

			/* No altsetting 0?  We'll assume the first altsetting.
			 * We could use a GetInterface call, but if a device is
			 * so non-compliant that it doesn't have altsetting 0
			 * then I wouldn't trust its reply anyway.
			 */
			if (!alt)
				alt = &intf->altsetting[0];

			intf->cur_altsetting = alt;
			usb_enable_interface(dev, intf);
			intf->dev.parent = &dev->dev;
			intf->dev.driver = NULL;
			intf->dev.bus = &usb_bus_type;
			intf->dev.dma_mask = dev->dev.dma_mask;
			intf->dev.release = release_interface;
			device_initialize (&intf->dev);
			sprintf (&intf->dev.bus_id[0], "%d-%s:%d.%d",
				 dev->bus->busnum, dev->devpath,
				 configuration,
				 alt->desc.bInterfaceNumber);
		}
		kfree(new_interfaces);

		/* Now that all the interfaces are set up, register them
		 * to trigger binding of drivers to interfaces.  probe()
		 * routines may install different altsettings and may
		 * claim() any interfaces not yet bound.  Many class drivers
		 * need that: CDC, audio, video, etc.
		 */
		for (i = 0; i < nintf; ++i) {
			struct usb_interface *intf = cp->interface[i];
			struct usb_interface_descriptor *desc;

			desc = &intf->altsetting [0].desc;
			dev_dbg (&dev->dev,
				"adding %s (config #%d, interface %d)\n",
				intf->dev.bus_id, configuration,
				desc->bInterfaceNumber);
			ret = device_add (&intf->dev);
			if (ret != 0) {
				dev_err(&dev->dev,
					"device_add(%s) --> %d\n",
					intf->dev.bus_id,
					ret);
				continue;
			}
			usb_create_sysfs_intf_files (intf);
		}
	}

	return ret;
}

// synchronous request completion model
EXPORT_SYMBOL(usb_control_msg);
EXPORT_SYMBOL(usb_bulk_msg);

EXPORT_SYMBOL(usb_sg_init);
EXPORT_SYMBOL(usb_sg_cancel);
EXPORT_SYMBOL(usb_sg_wait);

// synchronous control message convenience routines
EXPORT_SYMBOL(usb_get_descriptor);
EXPORT_SYMBOL(usb_get_status);
EXPORT_SYMBOL(usb_get_string);
EXPORT_SYMBOL(usb_string);

// synchronous calls that also maintain usbcore state
EXPORT_SYMBOL(usb_clear_halt);
EXPORT_SYMBOL(usb_reset_configuration);
EXPORT_SYMBOL(usb_set_interface);