usb.c

是关于linux2.5.1的完全源码

	data [1] = 3;
	return data [0];
}

/*
 * __usb_get_extra_descriptor() finds a descriptor of specific type in the
 * extra field of the interface and endpoint descriptor structs.
 */

int __usb_get_extra_descriptor(char *buffer, unsigned size, unsigned char type, void **ptr)
{
	struct usb_descriptor_header *header;

	while (size >= sizeof(struct usb_descriptor_header)) {
		header = (struct usb_descriptor_header *)buffer;

		if (header->bLength < 2) {
			err("invalid descriptor length of %d", header->bLength);
			return -1;
		}

		if (header->bDescriptorType == type) {
			*ptr = header;
			return 0;
		}

		buffer += header->bLength;
		size -= header->bLength;
	}
	return -1;
}

/**
 * usb_disconnect - disconnect a device (usbcore-internal)
 * @pdev: pointer to device being disconnected
 * Context: !in_interrupt ()
 *
 * Something got disconnected. Get rid of it, and all of its children.
 *
 * Only hub drivers (including virtual root hub drivers for host
 * controllers) should ever call this.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 */
void usb_disconnect(struct usb_device **pdev)
{
	struct usb_device * dev = *pdev;
	int i;

	if (!dev)
		return;

	*pdev = NULL;

	info("USB disconnect on device %d", dev->devnum);

	if (dev->actconfig) {
		for (i = 0; i < dev->actconfig->bNumInterfaces; i++) {
			struct usb_interface *interface = &dev->actconfig->interface[i];
			struct usb_driver *driver = interface->driver;
			if (driver) {
				if (driver->owner)
					__MOD_INC_USE_COUNT(driver->owner);
				down(&driver->serialize);
				driver->disconnect(dev, interface->private_data);
				up(&driver->serialize);
				if (driver->owner)
					__MOD_DEC_USE_COUNT(driver->owner);
				/* if driver->disconnect didn't release the interface */
				if (interface->driver)
					usb_driver_release_interface(driver, interface);
			}
			/* remove our device node for this interface */
			put_device(&interface->dev);
		}
	}

	/* Free up all the children.. */
	for (i = 0; i < USB_MAXCHILDREN; i++) {
		struct usb_device **child = dev->children + i;
		if (*child)
			usb_disconnect(child);
	}

	/* Let policy agent unload modules etc */
	call_policy ("remove", dev);

	/* Free the device number and remove the /proc/bus/usb entry */
	if (dev->devnum > 0) {
		clear_bit(dev->devnum, dev->bus->devmap.devicemap);
		usbfs_remove_device(dev);
		put_device(&dev->dev);
	}

	/* Free up the device itself */
	usb_free_dev(dev);
}

/**
 * usb_connect - connects a new device during enumeration (usbcore-internal)
 * @dev: partially enumerated device
 *
 * Connect a new USB device. This basically just initializes
 * the USB device information and sets up the topology - it's
 * up to the low-level driver to reset the port and actually
 * do the setup (the upper levels don't know how to do that).
 *
 * Only hub drivers (including virtual root hub drivers for host
 * controllers) should ever call this.
 */
void usb_connect(struct usb_device *dev)
{
	int devnum;
	// FIXME needs locking for SMP!!
	/* why? this is called only from the hub thread, 
	 * which hopefully doesn't run on multiple CPU's simultaneously 8-)
	 * ... it's also called from modprobe/rmmod/apmd threads as part
	 * of virtual root hub init/reinit.  In the init case, the hub code 
	 * won't have seen this, but not so for reinit ... 
	 */
	dev->descriptor.bMaxPacketSize0 = 8;  /* Start off at 8 bytes  */
#ifndef DEVNUM_ROUND_ROBIN
	devnum = find_next_zero_bit(dev->bus->devmap.devicemap, 128, 1);
#else	/* round_robin alloc of devnums */
	/* Try to allocate the next devnum beginning at bus->devnum_next. */
	devnum = find_next_zero_bit(dev->bus->devmap.devicemap, 128, dev->bus->devnum_next);
	if (devnum >= 128)
		devnum = find_next_zero_bit(dev->bus->devmap.devicemap, 128, 1);

	dev->bus->devnum_next = ( devnum >= 127 ? 1 : devnum + 1);
#endif	/* round_robin alloc of devnums */

	if (devnum < 128) {
		set_bit(devnum, dev->bus->devmap.devicemap);
		dev->devnum = devnum;
	}
}

/*
 * These are the actual routines to send
 * and receive control messages.
 */

// hub-only!! ... and only exported for reset/reinit path.
// otherwise used internally, for usb_new_device()
int usb_set_address(struct usb_device *dev)
{
	return usb_control_msg(dev, usb_snddefctrl(dev), USB_REQ_SET_ADDRESS,
		// FIXME USB_CTRL_SET_TIMEOUT
		0, dev->devnum, 0, NULL, 0, HZ * USB_CTRL_GET_TIMEOUT);
}

/**
 * usb_get_descriptor - issues a generic GET_DESCRIPTOR request
 * @dev: the device whose descriptor is being retrieved
 * @type: the descriptor type (USB_DT_*)
 * @index: the number of the descriptor
 * @buf: where to put the descriptor
 * @size: how big is "buf"?
 * Context: !in_interrupt ()
 *
 * Gets a USB descriptor.  Convenience functions exist to simplify
 * getting some types of descriptors.  Use
 * usb_get_device_descriptor() for USB_DT_DEVICE,
 * and usb_get_string() or usb_string() for USB_DT_STRING.
 * Configuration descriptors (USB_DT_CONFIG) are part of the device
 * structure, at least for the current configuration.
 * In addition to a number of USB-standard descriptors, some
 * devices also use class-specific or vendor-specific descriptors.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Returns zero on success, or else the status code returned by the
 * underlying usb_control_msg() call.
 */
int usb_get_descriptor(struct usb_device *dev, unsigned char type, unsigned char index, void *buf, int size)
{
	int i = 5;
	int result;
	
	memset(buf,0,size);	// Make sure we parse really received data

	while (i--) {
		/* retries if the returned length was 0; flakey device */
		if ((result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
				    USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
				    (type << 8) + index, 0, buf, size,
				    HZ * USB_CTRL_GET_TIMEOUT)) > 0
				|| result == -EPIPE)
			break;
	}
	return result;
}

/**
 * usb_get_string - gets a string descriptor
 * @dev: the device whose string descriptor is being retrieved
 * @langid: code for language chosen (from string descriptor zero)
 * @index: the number of the descriptor
 * @buf: where to put the string
 * @size: how big is "buf"?
 * Context: !in_interrupt ()
 *
 * Retrieves a string, encoded using UTF-16LE (Unicode, 16 bits per character,
 * in little-endian byte order).
 * The usb_string() function will often be a convenient way to turn
 * these strings into kernel-printable form.
 *
 * Strings may be referenced in device, configuration, interface, or other
 * descriptors, and could also be used in vendor-specific ways.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Returns zero on success, or else the status code returned by the
 * underlying usb_control_msg() call.
 */
int usb_get_string(struct usb_device *dev, unsigned short langid, unsigned char index, void *buf, int size)
{
	return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
		USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
		(USB_DT_STRING << 8) + index, langid, buf, size,
		HZ * USB_CTRL_GET_TIMEOUT);
}

/**
 * usb_get_device_descriptor - (re)reads the device descriptor
 * @dev: the device whose device descriptor is being updated
 * Context: !in_interrupt ()
 *
 * Updates the copy of the device descriptor stored in the device structure,
 * which dedicates space for this purpose.  Note that several fields are
 * converted to the host CPU's byte order:  the USB version (bcdUSB), and
 * vendors product and version fields (idVendor, idProduct, and bcdDevice).
 * That lets device drivers compare against non-byteswapped constants.
 *
 * There's normally no need to use this call, although some devices
 * will change their descriptors after events like updating firmware.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Returns zero on success, or else the status code returned by the
 * underlying usb_control_msg() call.
 */
int usb_get_device_descriptor(struct usb_device *dev)
{
	int ret = usb_get_descriptor(dev, USB_DT_DEVICE, 0, &dev->descriptor,
				     sizeof(dev->descriptor));
	if (ret >= 0) {
		le16_to_cpus(&dev->descriptor.bcdUSB);
		le16_to_cpus(&dev->descriptor.idVendor);
		le16_to_cpus(&dev->descriptor.idProduct);
		le16_to_cpus(&dev->descriptor.bcdDevice);
	}
	return ret;
}

/**
 * usb_get_status - issues a GET_STATUS call
 * @dev: the device whose status is being checked
 * @type: USB_RECIP_*; for device, interface, or endpoint
 * @target: zero (for device), else interface or endpoint number
 * @data: pointer to two bytes of bitmap data
 * Context: !in_interrupt ()
 *
 * Returns device, interface, or endpoint status.  Normally only of
 * interest to see if the device is self powered, or has enabled the
 * remote wakeup facility; or whether a bulk or interrupt endpoint
 * is halted ("stalled").
 *
 * Bits in these status bitmaps are set using the SET_FEATURE request,
 * and cleared using the CLEAR_FEATURE request.  The usb_clear_halt()
 * function should be used to clear halt ("stall") status.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Returns zero on success, or else the status code returned by the
 * underlying usb_control_msg() call.
 */
int usb_get_status(struct usb_device *dev, int type, int target, void *data)
{
	return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
		USB_REQ_GET_STATUS, USB_DIR_IN | type, 0, target, data, 2,
		HZ * USB_CTRL_GET_TIMEOUT);
}


// hub-only!! ... and only exported for reset/reinit path.
// otherwise used internally, for config/altsetting reconfig.
void usb_set_maxpacket(struct usb_device *dev)
{
	int i, b;

	for (i=0; i<dev->actconfig->bNumInterfaces; i++) {
		struct usb_interface *ifp = dev->actconfig->interface + i;
		struct usb_interface_descriptor *as = ifp->altsetting + ifp->act_altsetting;
		struct usb_endpoint_descriptor *ep = as->endpoint;
		int e;

		for (e=0; e<as->bNumEndpoints; e++) {
			b = ep[e].bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
			if ((ep[e].bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
				USB_ENDPOINT_XFER_CONTROL) {	/* Control => bidirectional */
				dev->epmaxpacketout[b] = ep[e].wMaxPacketSize;
				dev->epmaxpacketin [b] = ep[e].wMaxPacketSize;
				}
			else if (usb_endpoint_out(ep[e].bEndpointAddress)) {
				if (ep[e].wMaxPacketSize > dev->epmaxpacketout[b])
					dev->epmaxpacketout[b] = ep[e].wMaxPacketSize;
			}
			else {
				if (ep[e].wMaxPacketSize > dev->epmaxpacketin [b])
					dev->epmaxpacketin [b] = ep[e].wMaxPacketSize;
			}
		}
	}
}

/**
 * usb_clear_halt - tells device to clear endpoint halt/stall condition
 * @dev: device whose endpoint is halted
 * @pipe: endpoint "pipe" being cleared
 * Context: !in_interrupt ()
 *
 * This is used to clear halt conditions for bulk and interrupt endpoints,
 * as reported by URB completion status.  Endpoints that are halted are
 * sometimes referred to as being "stalled".  Such endpoints are unable
 * to transmit or receive data until the halt status is cleared.  Any URBs
 * queued queued for such an endpoint should normally be unlinked before
 * clearing the halt condition.
 *
 * Note that control and isochronous endpoints don't halt, although control
 * endpoints report "protocol stall" (for unsupported requests) using the
 * same status code used to report a true stall.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Returns zero on success, or else the status code returned by the
 * underlying usb_control_msg() call.
 */
int usb_clear_halt(struct usb_device *dev, int pipe)
{
	int result;
	__u16 status;
	unsigned char *buffer;
	int endp=usb_pipeendpoint(pipe)|(usb_pipein(pipe)<<7);

/*
	if (!usb_endpoint_halted(dev, endp & 0x0f, usb_endpoint_out(endp)))
		return 0;
*/

	result = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
		USB_REQ_CLEAR_FEATURE, USB_RECIP_ENDPOINT, 0, endp, NULL, 0,
		HZ * USB_CTRL_SET_TIMEOUT);

	/* don't clear if failed */
	if (result < 0)
		return result;

	buffer = kmalloc(sizeof(status), GFP_KERNEL);
	if (!buffer) {
		err("unable to allocate memory for configuration descriptors");
		return -ENOMEM;
	}

	result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
		USB_REQ_GET_STATUS, USB_DIR_IN | USB_RECIP_ENDPOINT, 0, endp,
		// FIXME USB_CTRL_GET_TIMEOUT, yes?  why not usb_get_status() ?
		buffer, sizeof(status), HZ * USB_CTRL_SET_TIMEOUT);

	memcpy(&status, buffer, sizeof(status));
	kfree(buffer);

	if (result < 0)
		return result;

	if (le16_to_cpu(status) & 1)
		return -EPIPE;		/* still halted */

	usb_endpoint_running(dev, usb_pipeendpoint(pipe), usb_pipeout(pipe));

	/* toggle is reset on clear */

	usb_settoggle(dev, usb_pipeendpoint(pipe), usb_pipeout(pipe), 0);

	return 0;
}

/**
 * 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.
 *
 * 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 about 4KBytes per
 * microframe, and isochronous endpoints may never be part of a an
 * interface's default setting.  To access such bandwidth, alternate
 * interface setting 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
 * 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.
 *
 * 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_interface_descriptor *iface_as;
	int i, ret;

	iface = usb_ifnum_to_if(dev, interface);
	if (!ifa