USB: add IAD support to usbfs and sysfs

USB_IAD: Adds support for USB Interface Association Descriptors.

This patch adds support to the USB host stack for parsing, storing, and
displaying Interface Association Descriptors. In /proc/bus/usb/devices
lines starting with A: show the fields in an IAD. In sysfs if an
interface on a USB device is referenced by an IAD the following files
will be added to the sysfs directory for that interface:
iad_bFirstInterface, iad_bInterfaceCount, iad_bFunctionClass, and
iad_bFunctionSubClass, iad_bFunctionProtocol

Signed-off-by: Craig W. Nadler <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/core/config.c

···
 	struct usb_descriptor_header *header;
 	int len, retval;
 	u8 inums[USB_MAXINTERFACES], nalts[USB_MAXINTERFACES];
+	unsigned iad_num = 0;
 
 	memcpy(&config->desc, buffer, USB_DT_CONFIG_SIZE);
 	if (config->desc.bDescriptorType != USB_DT_CONFIG ||
···
 				inums[n] = inum;
 				nalts[n] = 1;
 				++n;
+			}
+
+		} else if (header->bDescriptorType ==
+				USB_DT_INTERFACE_ASSOCIATION) {
+			if (iad_num == USB_MAXIADS) {
+				dev_warn(ddev, "found more Interface "
+					       "Association Descriptors "
+					       "than allocated for in "
+					       "configuration %d\n", cfgno);
+			} else {
+				config->intf_assoc[iad_num] =
+					(struct usb_interface_assoc_descriptor
+					*)header;
+				iad_num++;
 			}
 
 		} else if (header->bDescriptorType == USB_DT_DEVICE ||

drivers/usb/core/devices.c

···
 /* C:  #Ifs=dd Cfg#=dd Atr=xx MPwr=dddmA */
   "C:%c #Ifs=%2d Cfg#=%2d Atr=%02x MxPwr=%3dmA\n";
   
+static const char *format_iad =
+/* A:  FirstIf#=dd IfCount=dd Cls=xx(sssss) Sub=xx Prot=xx */
+  "A:  FirstIf#=%2d IfCount=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x\n";
+
 static const char *format_iface =
 /* I:  If#=dd Alt=dd #EPs=dd Cls=xx(sssss) Sub=xx Prot=xx Driver=xxxx*/
   "I:%c If#=%2d Alt=%2d #EPs=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x Driver=%s\n";
···
 	{USB_CLASS_STILL_IMAGE,		"still"},
 	{USB_CLASS_CSCID,		"scard"},
 	{USB_CLASS_CONTENT_SEC,		"c-sec"},
+	{USB_CLASS_VIDEO,		"video"},
 	{-1,				"unk."}		/* leave as last */
 };
 
···
 	return start;
 }
 
+static char *usb_dump_iad_descriptor(char *start, char *end,
+	const struct usb_interface_assoc_descriptor *iad)
+{
+	if (start > end)
+		return start;
+	start += sprintf(start, format_iad,
+			 iad->bFirstInterface,
+			 iad->bInterfaceCount,
+			 iad->bFunctionClass,
+			 class_decode(iad->bFunctionClass),
+			 iad->bFunctionSubClass,
+			 iad->bFunctionProtocol);
+	return start;
+}
+
 /* TBD:
  * 0. TBDs
  * 1. marking active interface altsettings (code lists all, but should mark
···
 	if (!config)		/* getting these some in 2.3.7; none in 2.3.6 */
 		return start + sprintf(start, "(null Cfg. desc.)\n");
 	start = usb_dump_config_descriptor(start, end, &config->desc, active);
+	for (i = 0; i < USB_MAXIADS; i++) {
+		if (config->intf_assoc[i] == NULL)
+			break;
+		start = usb_dump_iad_descriptor(start, end,
+					config->intf_assoc[i]);
+	}
 	for (i = 0; i < config->desc.bNumInterfaces; i++) {
 		intfc = config->intf_cache[i];
 		interface = config->interface[i];

drivers/usb/core/message.c

···
 	.uevent =	usb_if_uevent,
 };
 
+static struct usb_interface_assoc_descriptor *find_iad(struct usb_device *dev,
+						       struct usb_host_config *config,
+						       u8 inum)
+{
+	struct usb_interface_assoc_descriptor *retval = NULL;
+	struct usb_interface_assoc_descriptor *intf_assoc;
+	int first_intf;
+	int last_intf;
+	int i;
+
+	for (i = 0; (i < USB_MAXIADS && config->intf_assoc[i]); i++) {
+		intf_assoc = config->intf_assoc[i];
+		if (intf_assoc->bInterfaceCount == 0)
+			continue;
+
+		first_intf = intf_assoc->bFirstInterface;
+		last_intf = first_intf + (intf_assoc->bInterfaceCount - 1);
+		if (inum >= first_intf && inum <= last_intf) {
+			if (!retval)
+				retval = intf_assoc;
+			else
+				dev_err(&dev->dev, "Interface #%d referenced"
+					" by multiple IADs\n", inum);
+		}
+	}
+
+	return retval;
+}
+
+
 /*
  * usb_set_configuration - Makes a particular device setting be current
  * @dev: the device whose configuration is being updated
···
 		intfc = cp->intf_cache[i];
 		intf->altsetting = intfc->altsetting;
 		intf->num_altsetting = intfc->num_altsetting;
+		intf->intf_assoc = find_iad(dev, cp, i);
 		kref_get(&intfc->ref);
 
 		alt = usb_altnum_to_altsetting(intf, 0);

drivers/usb/core/sysfs.c

···
 	sysfs_remove_group(&dev->kobj, &dev_attr_grp);
 }
 
+/* Interface Accociation Descriptor fields */
+#define usb_intf_assoc_attr(field, format_string)			\
+static ssize_t								\
+show_iad_##field (struct device *dev, struct device_attribute *attr,	\
+		char *buf)						\
+{									\
+	struct usb_interface *intf = to_usb_interface (dev);		\
+									\
+	return sprintf (buf, format_string,				\
+			intf->intf_assoc->field); 		\
+}									\
+static DEVICE_ATTR(iad_##field, S_IRUGO, show_iad_##field, NULL);
+
+usb_intf_assoc_attr (bFirstInterface, "%02x\n")
+usb_intf_assoc_attr (bInterfaceCount, "%02d\n")
+usb_intf_assoc_attr (bFunctionClass, "%02x\n")
+usb_intf_assoc_attr (bFunctionSubClass, "%02x\n")
+usb_intf_assoc_attr (bFunctionProtocol, "%02x\n")
+
 /* Interface fields */
 #define usb_intf_attr(field, format_string)				\
 static ssize_t								\
···
 }
 static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
 
+static struct attribute *intf_assoc_attrs[] = {
+	&dev_attr_iad_bFirstInterface.attr,
+	&dev_attr_iad_bInterfaceCount.attr,
+	&dev_attr_iad_bFunctionClass.attr,
+	&dev_attr_iad_bFunctionSubClass.attr,
+	&dev_attr_iad_bFunctionProtocol.attr,
+	NULL,
+};
+static struct attribute_group intf_assoc_attr_grp = {
+	.attrs = intf_assoc_attrs,
+};
+
 static struct attribute *intf_attrs[] = {
 	&dev_attr_bInterfaceNumber.attr,
 	&dev_attr_bAlternateSetting.attr,
···
 		alt->string = usb_cache_string(udev, alt->desc.iInterface);
 	if (alt->string)
 		retval = device_create_file(dev, &dev_attr_interface);
+	if (intf->intf_assoc)
+		retval = sysfs_create_group(&dev->kobj, &intf_assoc_attr_grp);
 	usb_create_intf_ep_files(intf, udev);
 	return 0;
 }
···
 	usb_remove_intf_ep_files(intf);
 	device_remove_file(dev, &dev_attr_interface);
 	sysfs_remove_group(&dev->kobj, &intf_attr_grp);
+	sysfs_remove_group(&intf->dev.kobj, &intf_assoc_attr_grp);
 }

include/linux/usb.h

···
 					 * active alternate setting */
 	unsigned num_altsetting;	/* number of alternate settings */
 
+	/* If there is an interface association descriptor then it will list
+	 * the associated interfaces */
+	struct usb_interface_assoc_descriptor *intf_assoc;
+
 	int minor;			/* minor number this interface is
 					 * bound to */
 	enum usb_interface_condition condition;		/* state of binding */
···
 
 /* this maximum is arbitrary */
 #define USB_MAXINTERFACES	32
+#define USB_MAXIADS		USB_MAXINTERFACES/2
 
 /**
  * struct usb_interface_cache - long-term representation of a device interface
···
 	struct usb_config_descriptor	desc;
 
 	char *string;		/* iConfiguration string, if present */
+
+	/* List of any Interface Association Descriptors in this
+	 * configuration. */
+	struct usb_interface_assoc_descriptor *intf_assoc[USB_MAXIADS];
+
 	/* the interfaces associated with this configuration,
 	 * stored in no particular order */
 	struct usb_interface *interface[USB_MAXINTERFACES];