message.c

h内核

		case 0:
			cpu_relax ();
			break;

			/* fail any uncompleted urbs */
		default:
			io->urbs [i]->dev = NULL;
			io->urbs [i]->status = retval;
			dev_dbg (&io->dev->dev, "%s, submit --> %d\n",
				__FUNCTION__, retval);
			usb_sg_cancel (io);
		}
		spin_lock_irq (&io->lock);
		if (retval && (io->status == 0 || io->status == -ECONNRESET))
			io->status = retval;
	}
	io->count -= entries - i;
	if (io->count == 0)
		complete (&io->complete);
	spin_unlock_irq (&io->lock);

	/* OK, yes, this could be packaged as non-blocking.
	 * So could the submit loop above ... but it's easier to
	 * solve neither problem than to solve both!
	 */
	wait_for_completion (&io->complete);

	sg_clean (io);
}

/**
 * usb_sg_cancel - stop scatter/gather i/o issued by usb_sg_wait()
 * @io: request block, initialized with usb_sg_init()
 *
 * This stops a request after it has been started by usb_sg_wait().
 * It can also prevents one initialized by usb_sg_init() from starting,
 * so that call just frees resources allocated to the request.
 */
void usb_sg_cancel (struct usb_sg_request *io)
{
	unsigned long	flags;

	spin_lock_irqsave (&io->lock, flags);

	/* shut everything down, if it didn't already */
	if (!io->status) {
		int	i;

		io->status = -ECONNRESET;
		spin_unlock (&io->lock);
		for (i = 0; i < io->entries; i++) {
			int	retval;

			if (!io->urbs [i]->dev)
				continue;
			retval = usb_unlink_urb (io->urbs [i]);
			if (retval != -EINPROGRESS && retval != -EBUSY)
				dev_warn (&io->dev->dev, "%s, unlink --> %d\n",
					__FUNCTION__, retval);
		}
		spin_lock (&io->lock);
	}
	spin_unlock_irqrestore (&io->lock, flags);
}

/*-------------------------------------------------------------------*/

/**
 * 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_string() or usb_string() for USB_DT_STRING.
 * Device (USB_DT_DEVICE) and configuration descriptors (USB_DT_CONFIG)
 * are part of the device structure.
 * 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 the number of bytes received 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;
	int result;
	
	memset(buf,0,size);	// Make sure we parse really received data

	for (i = 0; i < 3; ++i) {
		/* retry on length 0 or stall; some devices are flakey */
		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);
		if (result == 0 || result == -EPIPE)
			continue;
		if (result > 1 && ((u8 *)buf)[1] != type) {
			result = -EPROTO;
			continue;
		}
		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 the number of bytes received 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)
{
	int i;
	int result;

	for (i = 0; i < 3; ++i) {
		/* retry on length 0 or stall; some devices are flakey */
		result = 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);
		if (!(result == 0 || result == -EPIPE))
			break;
	}
	return result;
}

static void usb_try_string_workarounds(unsigned char *buf, int *length)
{
	int newlength, oldlength = *length;

	for (newlength = 2; newlength + 1 < oldlength; newlength += 2)
		if (!isprint(buf[newlength]) || buf[newlength + 1])
			break;

	if (newlength > 2) {
		buf[0] = newlength;
		*length = newlength;
	}
}

static int usb_string_sub(struct usb_device *dev, unsigned int langid,
		unsigned int index, unsigned char *buf)
{
	int rc;

	/* Try to read the string descriptor by asking for the maximum
	 * possible number of bytes */
	rc = usb_get_string(dev, langid, index, buf, 255);

	/* If that failed try to read the descriptor length, then
	 * ask for just that many bytes */
	if (rc < 2) {
		rc = usb_get_string(dev, langid, index, buf, 2);
		if (rc == 2)
			rc = usb_get_string(dev, langid, index, buf, buf[0]);
	}

	if (rc >= 2) {
		if (!buf[0] && !buf[1])
			usb_try_string_workarounds(buf, &rc);

		/* There might be extra junk at the end of the descriptor */
		if (buf[0] < rc)
			rc = buf[0];

		rc = rc - (rc & 1); /* force a multiple of two */
	}

	if (rc < 2)
		rc = (rc < 0 ? rc : -EINVAL);

	return rc;
}

/**
 * usb_string - returns ISO 8859-1 version of a string descriptor
 * @dev: the device whose string descriptor is being retrieved
 * @index: the number of the descriptor
 * @buf: where to put the string
 * @size: how big is "buf"?
 * Context: !in_interrupt ()
 * 
 * This converts the UTF-16LE encoded strings returned by devices, from
 * usb_get_string_descriptor(), to null-terminated ISO-8859-1 encoded ones
 * that are more usable in most kernel contexts.  Note that all characters
 * in the chosen descriptor that can't be encoded using ISO-8859-1
 * are converted to the question mark ("?") character, and this function
 * chooses strings in the first language supported by the device.
 *
 * The ASCII (or, redundantly, "US-ASCII") character set is the seven-bit
 * subset of ISO 8859-1. ISO-8859-1 is the eight-bit subset of Unicode,
 * and is appropriate for use many uses of English and several other
 * Western European languages.  (But it doesn't include the "Euro" symbol.)
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Returns length of the string (>= 0) or usb_control_msg status (< 0).
 */
int usb_string(struct usb_device *dev, int index, char *buf, size_t size)
{
	unsigned char *tbuf;
	int err;
	unsigned int u, idx;

	if (dev->state == USB_STATE_SUSPENDED)
		return -EHOSTUNREACH;
	if (size <= 0 || !buf || !index)
		return -EINVAL;
	buf[0] = 0;
	tbuf = kmalloc(256, GFP_KERNEL);
	if (!tbuf)
		return -ENOMEM;

	/* get langid for strings if it's not yet known */
	if (!dev->have_langid) {
		err = usb_string_sub(dev, 0, 0, tbuf);
		if (err < 0) {
			dev_err (&dev->dev,
				"string descriptor 0 read error: %d\n",
				err);
			goto errout;
		} else if (err < 4) {
			dev_err (&dev->dev, "string descriptor 0 too short\n");
			err = -EINVAL;
			goto errout;
		} else {
			dev->have_langid = -1;
			dev->string_langid = tbuf[2] | (tbuf[3]<< 8);
				/* always use the first langid listed */
			dev_dbg (&dev->dev, "default language 0x%04x\n",
				dev->string_langid);
		}
	}
	
	err = usb_string_sub(dev, dev->string_langid, index, tbuf);
	if (err < 0)
		goto errout;

	size--;		/* leave room for trailing NULL char in output buffer */
	for (idx = 0, u = 2; u < err; u += 2) {
		if (idx >= size)
			break;
		if (tbuf[u+1])			/* high byte */
			buf[idx++] = '?';  /* non ISO-8859-1 character */
		else
			buf[idx++] = tbuf[u];
	}
	buf[idx] = 0;
	err = idx;

	if (tbuf[1] != USB_DT_STRING)
		dev_dbg(&dev->dev, "wrong descriptor type %02x for string %d (\"%s\")\n", tbuf[1], index, buf);

 errout:
	kfree(tbuf);
	return err;
}

/*
 * usb_get_device_descriptor - (re)reads the device descriptor (usbcore)
 * @dev: the device whose device descriptor is being updated
 * @size: how much of the descriptor to read
 * 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.
 *
 * Not exported, only for use by the core.  If drivers really want to read
 * the device descriptor directly, they can call usb_get_descriptor() with
 * type = USB_DT_DEVICE and index = 0.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Returns the number of bytes received on success, or else the status code
 * returned by the underlying usb_control_msg() call.
 */
int usb_get_device_descriptor(struct usb_device *dev, unsigned int size)
{
	struct usb_device_descriptor *desc;
	int ret;

	if (size > sizeof(*desc))
		return -EINVAL;
	desc = kmalloc(sizeof(*desc), GFP_NOIO);
	if (!desc)
		return -ENOMEM;

	ret = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, size);
	if (ret >= 0) 
		memcpy(&dev->descriptor, desc, size);
	kfree(desc);
	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 the number of bytes received 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)
{
	int ret;
	u16 *status = kmalloc(sizeof(*status), GFP_KERNEL);

	if (!status)
		return -ENOMEM;

	ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
		USB_REQ_GET_STATUS, USB_DIR_IN | type, 0, target, status,
		sizeof(*status), HZ * USB_CTRL_GET_TIMEOUT);

	*(u16 *)data = *status;
	kfree(status);
	return ret;
}

/**
 * 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 for such an endpoint should normally be unlinked by the driver
 * before clearing the halt condition, as described in sections 5.7.5
 * and 5.8.5 of the USB 2.0 spec.
 *
 * 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;
	int endp = usb_pipeendpoint(pipe);
	
	if (usb_pipein (pipe))
		endp |= USB_DIR_IN;

	/* we don't care if it wasn't halted first. in fact some devices
	 * (like some ibmcam model 1 units) seem to expect hosts to make
	 * this request for iso endpoints, which can't halt!
	 */
	result = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
		USB_REQ_CLEAR_FEATURE, USB_RECIP_ENDPOINT,
		USB_ENDPOINT_HALT, endp, NULL, 0,
		HZ * USB_CTRL_SET_TIMEOUT);

	/* don't un-halt or force to DATA0 except on success */
	if (result < 0)
		return result;

	/* NOTE:  seems like Microsoft and Apple don't bother verifying
	 * the clear "took", so some devices could lock up if you check...
	 * such as the Hagiwara FlashGate DUAL.  So we won't bother.
	 *
	 * NOTE:  make sure the logic here doesn't diverge much from
	 * the copy in usb-storage, for as long as we need two copies.
	 */

	/* toggle was reset by the clear */
	usb_settoggle(dev, usb_pipeendpoint(pipe), usb_pipeout(pipe), 0);

	return 0;
}

/**
 * usb_disable_endpoint -- Disable an endpoint by address
 * @dev: the device whose endpoint is being disabled
 * @epaddr: the endpoint's address.  Endpoint number for output,
 *	endpoint number + USB_DIR_IN for input
 *
 * Deallocates hcd/hardware state for this endpoint ... and nukes all
 * pending urbs.
 *
 * If the HCD hasn't registered a disable() function, this sets the
 * endpoint's maxpacket size to 0 to prevent further submissions.
 */
void usb_disable_endpoint(struct usb_device *dev, unsigned int epaddr)
{
	unsigned int epnum = epaddr & USB_ENDPOINT_NUMBER_MASK;
	struct usb_host_endpoint *ep;

	if (!dev)
		return;

	if (usb_endpoint_out(epaddr)) {
		ep = dev->ep_out[epnum];
		dev->ep_out[epnum] = NULL;
	} else {
		ep = dev->ep_in[epnum];
		dev->ep_in[epnum] = NULL;
	}
	if (ep && dev->bus && dev->bus->op && dev->bus->op->disable)
		dev->bus->op->disable(dev, ep);
}

/**
 * usb_disable_interface -- Disable all endpoints for an interface
 * @dev: the device whose interface is being disabled
 * @intf: pointer to the interface descriptor
 *
 * Disables all the endpoints for the interface's current altsetting.
 */
void usb_disable_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_disable_endpoint(dev,
				alt->endpoint[i].desc.bEndpointAddress);
	}
}

/*
 * usb_disable_device - Disable all the endpoints for a USB device
 * @dev: the device whose endpoints are being disabled
 * @skip_ep0: 0 to disable endpoint 0, 1 to skip it.
 *
 * Disables all the device's endpoints, potentially including endpoint 0.
 * Deallocates hcd/hardware state for the endpoints (nuking all or most
 * pending urbs) and usbcore state for the interfaces, so that usbcore
 * must usb_set_configuration() before any interfaces could be used.
 */