Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2490 insertions, 0 deletions

diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
new file mode 100644
index 000000000..015a7bbd9
--- /dev/null
+++ b/drivers/usb/gadget/function/uvc_configfs.c
@@ -0,0 +1,2490 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * uvc_configfs.c
+ *
+ * Configfs support for the uvc function.
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ *		http://www.samsung.com
+ *
+ * Author: Andrzej Pietrasiewicz <andrzejtp2010@gmail.com>
+ */
+
+#include "uvc_configfs.h"
+
+#include <linux/sort.h>
+
+/* -----------------------------------------------------------------------------
+ * Global Utility Structures and Macros
+ */
+
+#define UVC_ATTR(prefix, cname, aname) \
+static struct configfs_attribute prefix##attr_##cname = { \
+	.ca_name	= __stringify(aname),				\
+	.ca_mode	= S_IRUGO | S_IWUGO,				\
+	.ca_owner	= THIS_MODULE,					\
+	.show		= prefix##cname##_show,				\
+	.store		= prefix##cname##_store,			\
+}
+
+#define UVC_ATTR_RO(prefix, cname, aname) \
+static struct configfs_attribute prefix##attr_##cname = { \
+	.ca_name	= __stringify(aname),				\
+	.ca_mode	= S_IRUGO,					\
+	.ca_owner	= THIS_MODULE,					\
+	.show		= prefix##cname##_show,				\
+}
+
+#define le8_to_cpu(x)	(x)
+#define cpu_to_le8(x)	(x)
+
+static int uvcg_config_compare_u32(const void *l, const void *r)
+{
+	u32 li = *(const u32 *)l;
+	u32 ri = *(const u32 *)r;
+
+	return li < ri ? -1 : li == ri ? 0 : 1;
+}
+
+struct uvcg_config_group_type {
+	struct config_item_type type;
+	const char *name;
+	const struct uvcg_config_group_type **children;
+	int (*create_children)(struct config_group *group);
+};
+
+static void uvcg_config_item_release(struct config_item *item)
+{
+	struct config_group *group = to_config_group(item);
+
+	kfree(group);
+}
+
+static struct configfs_item_operations uvcg_config_item_ops = {
+	.release	= uvcg_config_item_release,
+};
+
+static int uvcg_config_create_group(struct config_group *parent,
+				    const struct uvcg_config_group_type *type);
+
+static int uvcg_config_create_children(struct config_group *group,
+				const struct uvcg_config_group_type *type)
+{
+	const struct uvcg_config_group_type **child;
+	int ret;
+
+	if (type->create_children)
+		return type->create_children(group);
+
+	for (child = type->children; child && *child; ++child) {
+		ret = uvcg_config_create_group(group, *child);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int uvcg_config_create_group(struct config_group *parent,
+				    const struct uvcg_config_group_type *type)
+{
+	struct config_group *group;
+
+	group = kzalloc(sizeof(*group), GFP_KERNEL);
+	if (!group)
+		return -ENOMEM;
+
+	config_group_init_type_name(group, type->name, &type->type);
+	configfs_add_default_group(group, parent);
+
+	return uvcg_config_create_children(group, type);
+}
+
+static void uvcg_config_remove_children(struct config_group *group)
+{
+	struct config_group *child, *n;
+
+	list_for_each_entry_safe(child, n, &group->default_groups, group_entry) {
+		list_del(&child->group_entry);
+		uvcg_config_remove_children(child);
+		config_item_put(&child->cg_item);
+	}
+}
+
+/* -----------------------------------------------------------------------------
+ * control/header/<NAME>
+ * control/header
+ */
+
+#define UVCG_CTRL_HDR_ATTR(cname, aname, bits, limit)			\
+static ssize_t uvcg_control_header_##cname##_show(			\
+	struct config_item *item, char *page)				\
+{									\
+	struct uvcg_control_header *ch = to_uvcg_control_header(item);	\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &ch->item.ci_group->cg_subsys->su_mutex;\
+	int result;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = ch->item.ci_parent->ci_parent->ci_parent;		\
+	opts = to_f_uvc_opts(opts_item);				\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", le##bits##_to_cpu(ch->desc.aname));\
+	mutex_unlock(&opts->lock);					\
+									\
+	mutex_unlock(su_mutex);						\
+	return result;							\
+}									\
+									\
+static ssize_t								\
+uvcg_control_header_##cname##_store(struct config_item *item,		\
+			   const char *page, size_t len)		\
+{									\
+	struct uvcg_control_header *ch = to_uvcg_control_header(item);	\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &ch->item.ci_group->cg_subsys->su_mutex;\
+	int ret;							\
+	u##bits num;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = ch->item.ci_parent->ci_parent->ci_parent;		\
+	opts = to_f_uvc_opts(opts_item);				\
+									\
+	mutex_lock(&opts->lock);					\
+	if (ch->linked || opts->refcnt) {				\
+		ret = -EBUSY;						\
+		goto end;						\
+	}								\
+									\
+	ret = kstrtou##bits(page, 0, &num);				\
+	if (ret)							\
+		goto end;						\
+									\
+	if (num > limit) {						\
+		ret = -EINVAL;						\
+		goto end;						\
+	}								\
+	ch->desc.aname = cpu_to_le##bits(num);				\
+	ret = len;							\
+end:									\
+	mutex_unlock(&opts->lock);					\
+	mutex_unlock(su_mutex);						\
+	return ret;							\
+}									\
+									\
+UVC_ATTR(uvcg_control_header_, cname, aname)
+
+UVCG_CTRL_HDR_ATTR(bcd_uvc, bcdUVC, 16, 0xffff);
+
+UVCG_CTRL_HDR_ATTR(dw_clock_frequency, dwClockFrequency, 32, 0x7fffffff);
+
+#undef UVCG_CTRL_HDR_ATTR
+
+static struct configfs_attribute *uvcg_control_header_attrs[] = {
+	&uvcg_control_header_attr_bcd_uvc,
+	&uvcg_control_header_attr_dw_clock_frequency,
+	NULL,
+};
+
+static const struct config_item_type uvcg_control_header_type = {
+	.ct_item_ops	= &uvcg_config_item_ops,
+	.ct_attrs	= uvcg_control_header_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_item *uvcg_control_header_make(struct config_group *group,
+						    const char *name)
+{
+	struct uvcg_control_header *h;
+
+	h = kzalloc(sizeof(*h), GFP_KERNEL);
+	if (!h)
+		return ERR_PTR(-ENOMEM);
+
+	h->desc.bLength			= UVC_DT_HEADER_SIZE(1);
+	h->desc.bDescriptorType		= USB_DT_CS_INTERFACE;
+	h->desc.bDescriptorSubType	= UVC_VC_HEADER;
+	h->desc.bcdUVC			= cpu_to_le16(0x0110);
+	h->desc.dwClockFrequency	= cpu_to_le32(48000000);
+
+	config_item_init_type_name(&h->item, name, &uvcg_control_header_type);
+
+	return &h->item;
+}
+
+static struct configfs_group_operations uvcg_control_header_grp_ops = {
+	.make_item		= uvcg_control_header_make,
+};
+
+static const struct uvcg_config_group_type uvcg_control_header_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_group_ops	= &uvcg_control_header_grp_ops,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "header",
+};
+
+/* -----------------------------------------------------------------------------
+ * control/processing/default
+ */
+
+#define UVCG_DEFAULT_PROCESSING_ATTR(cname, aname, bits)		\
+static ssize_t uvcg_default_processing_##cname##_show(			\
+	struct config_item *item, char *page)				\
+{									\
+	struct config_group *group = to_config_group(item);		\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &group->cg_subsys->su_mutex;		\
+	struct uvc_processing_unit_descriptor *pd;			\
+	int result;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = group->cg_item.ci_parent->ci_parent->ci_parent;	\
+	opts = to_f_uvc_opts(opts_item);				\
+	pd = &opts->uvc_processing;					\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", le##bits##_to_cpu(pd->aname));	\
+	mutex_unlock(&opts->lock);					\
+									\
+	mutex_unlock(su_mutex);						\
+	return result;							\
+}									\
+									\
+UVC_ATTR_RO(uvcg_default_processing_, cname, aname)
+
+UVCG_DEFAULT_PROCESSING_ATTR(b_unit_id, bUnitID, 8);
+UVCG_DEFAULT_PROCESSING_ATTR(b_source_id, bSourceID, 8);
+UVCG_DEFAULT_PROCESSING_ATTR(w_max_multiplier, wMaxMultiplier, 16);
+UVCG_DEFAULT_PROCESSING_ATTR(i_processing, iProcessing, 8);
+
+#undef UVCG_DEFAULT_PROCESSING_ATTR
+
+static ssize_t uvcg_default_processing_bm_controls_show(
+	struct config_item *item, char *page)
+{
+	struct config_group *group = to_config_group(item);
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+	struct uvc_processing_unit_descriptor *pd;
+	int result, i;
+	char *pg = page;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = group->cg_item.ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+	pd = &opts->uvc_processing;
+
+	mutex_lock(&opts->lock);
+	for (result = 0, i = 0; i < pd->bControlSize; ++i) {
+		result += sprintf(pg, "%u\n", pd->bmControls[i]);
+		pg = page + result;
+	}
+	mutex_unlock(&opts->lock);
+
+	mutex_unlock(su_mutex);
+
+	return result;
+}
+
+UVC_ATTR_RO(uvcg_default_processing_, bm_controls, bmControls);
+
+static struct configfs_attribute *uvcg_default_processing_attrs[] = {
+	&uvcg_default_processing_attr_b_unit_id,
+	&uvcg_default_processing_attr_b_source_id,
+	&uvcg_default_processing_attr_w_max_multiplier,
+	&uvcg_default_processing_attr_bm_controls,
+	&uvcg_default_processing_attr_i_processing,
+	NULL,
+};
+
+static const struct uvcg_config_group_type uvcg_default_processing_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_attrs	= uvcg_default_processing_attrs,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "default",
+};
+
+/* -----------------------------------------------------------------------------
+ * control/processing
+ */
+
+static const struct uvcg_config_group_type uvcg_processing_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "processing",
+	.children = (const struct uvcg_config_group_type*[]) {
+		&uvcg_default_processing_type,
+		NULL,
+	},
+};
+
+/* -----------------------------------------------------------------------------
+ * control/terminal/camera/default
+ */
+
+#define UVCG_DEFAULT_CAMERA_ATTR(cname, aname, bits)			\
+static ssize_t uvcg_default_camera_##cname##_show(			\
+	struct config_item *item, char *page)				\
+{									\
+	struct config_group *group = to_config_group(item);		\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &group->cg_subsys->su_mutex;		\
+	struct uvc_camera_terminal_descriptor *cd;			\
+	int result;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = group->cg_item.ci_parent->ci_parent->ci_parent->	\
+			ci_parent;					\
+	opts = to_f_uvc_opts(opts_item);				\
+	cd = &opts->uvc_camera_terminal;				\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", le##bits##_to_cpu(cd->aname));	\
+	mutex_unlock(&opts->lock);					\
+									\
+	mutex_unlock(su_mutex);						\
+									\
+	return result;							\
+}									\
+									\
+UVC_ATTR_RO(uvcg_default_camera_, cname, aname)
+
+UVCG_DEFAULT_CAMERA_ATTR(b_terminal_id, bTerminalID, 8);
+UVCG_DEFAULT_CAMERA_ATTR(w_terminal_type, wTerminalType, 16);
+UVCG_DEFAULT_CAMERA_ATTR(b_assoc_terminal, bAssocTerminal, 8);
+UVCG_DEFAULT_CAMERA_ATTR(i_terminal, iTerminal, 8);
+UVCG_DEFAULT_CAMERA_ATTR(w_objective_focal_length_min, wObjectiveFocalLengthMin,
+			 16);
+UVCG_DEFAULT_CAMERA_ATTR(w_objective_focal_length_max, wObjectiveFocalLengthMax,
+			 16);
+UVCG_DEFAULT_CAMERA_ATTR(w_ocular_focal_length, wOcularFocalLength,
+			 16);
+
+#undef UVCG_DEFAULT_CAMERA_ATTR
+
+static ssize_t uvcg_default_camera_bm_controls_show(
+	struct config_item *item, char *page)
+{
+	struct config_group *group = to_config_group(item);
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+	struct uvc_camera_terminal_descriptor *cd;
+	int result, i;
+	char *pg = page;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = group->cg_item.ci_parent->ci_parent->ci_parent->
+			ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+	cd = &opts->uvc_camera_terminal;
+
+	mutex_lock(&opts->lock);
+	for (result = 0, i = 0; i < cd->bControlSize; ++i) {
+		result += sprintf(pg, "%u\n", cd->bmControls[i]);
+		pg = page + result;
+	}
+	mutex_unlock(&opts->lock);
+
+	mutex_unlock(su_mutex);
+	return result;
+}
+
+UVC_ATTR_RO(uvcg_default_camera_, bm_controls, bmControls);
+
+static struct configfs_attribute *uvcg_default_camera_attrs[] = {
+	&uvcg_default_camera_attr_b_terminal_id,
+	&uvcg_default_camera_attr_w_terminal_type,
+	&uvcg_default_camera_attr_b_assoc_terminal,
+	&uvcg_default_camera_attr_i_terminal,
+	&uvcg_default_camera_attr_w_objective_focal_length_min,
+	&uvcg_default_camera_attr_w_objective_focal_length_max,
+	&uvcg_default_camera_attr_w_ocular_focal_length,
+	&uvcg_default_camera_attr_bm_controls,
+	NULL,
+};
+
+static const struct uvcg_config_group_type uvcg_default_camera_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_attrs	= uvcg_default_camera_attrs,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "default",
+};
+
+/* -----------------------------------------------------------------------------
+ * control/terminal/camera
+ */
+
+static const struct uvcg_config_group_type uvcg_camera_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "camera",
+	.children = (const struct uvcg_config_group_type*[]) {
+		&uvcg_default_camera_type,
+		NULL,
+	},
+};
+
+/* -----------------------------------------------------------------------------
+ * control/terminal/output/default
+ */
+
+#define UVCG_DEFAULT_OUTPUT_ATTR(cname, aname, bits)			\
+static ssize_t uvcg_default_output_##cname##_show(			\
+	struct config_item *item, char *page)				\
+{									\
+	struct config_group *group = to_config_group(item);		\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &group->cg_subsys->su_mutex;		\
+	struct uvc_output_terminal_descriptor *cd;			\
+	int result;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = group->cg_item.ci_parent->ci_parent->		\
+			ci_parent->ci_parent;				\
+	opts = to_f_uvc_opts(opts_item);				\
+	cd = &opts->uvc_output_terminal;				\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", le##bits##_to_cpu(cd->aname));	\
+	mutex_unlock(&opts->lock);					\
+									\
+	mutex_unlock(su_mutex);						\
+									\
+	return result;							\
+}									\
+									\
+UVC_ATTR_RO(uvcg_default_output_, cname, aname)
+
+UVCG_DEFAULT_OUTPUT_ATTR(b_terminal_id, bTerminalID, 8);
+UVCG_DEFAULT_OUTPUT_ATTR(w_terminal_type, wTerminalType, 16);
+UVCG_DEFAULT_OUTPUT_ATTR(b_assoc_terminal, bAssocTerminal, 8);
+UVCG_DEFAULT_OUTPUT_ATTR(i_terminal, iTerminal, 8);
+
+#undef UVCG_DEFAULT_OUTPUT_ATTR
+
+static ssize_t uvcg_default_output_b_source_id_show(struct config_item *item,
+						    char *page)
+{
+	struct config_group *group = to_config_group(item);
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+	struct uvc_output_terminal_descriptor *cd;
+	int result;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = group->cg_item.ci_parent->ci_parent->
+			ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+	cd = &opts->uvc_output_terminal;
+
+	mutex_lock(&opts->lock);
+	result = sprintf(page, "%u\n", le8_to_cpu(cd->bSourceID));
+	mutex_unlock(&opts->lock);
+
+	mutex_unlock(su_mutex);
+
+	return result;
+}
+
+static ssize_t uvcg_default_output_b_source_id_store(struct config_item *item,
+						     const char *page, size_t len)
+{
+	struct config_group *group = to_config_group(item);
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+	struct uvc_output_terminal_descriptor *cd;
+	int result;
+	u8 num;
+
+	result = kstrtou8(page, 0, &num);
+	if (result)
+		return result;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = group->cg_item.ci_parent->ci_parent->
+			ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+	cd = &opts->uvc_output_terminal;
+
+	mutex_lock(&opts->lock);
+	cd->bSourceID = num;
+	mutex_unlock(&opts->lock);
+
+	mutex_unlock(su_mutex);
+
+	return len;
+}
+UVC_ATTR(uvcg_default_output_, b_source_id, bSourceID);
+
+static struct configfs_attribute *uvcg_default_output_attrs[] = {
+	&uvcg_default_output_attr_b_terminal_id,
+	&uvcg_default_output_attr_w_terminal_type,
+	&uvcg_default_output_attr_b_assoc_terminal,
+	&uvcg_default_output_attr_b_source_id,
+	&uvcg_default_output_attr_i_terminal,
+	NULL,
+};
+
+static const struct uvcg_config_group_type uvcg_default_output_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_attrs	= uvcg_default_output_attrs,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "default",
+};
+
+/* -----------------------------------------------------------------------------
+ * control/terminal/output
+ */
+
+static const struct uvcg_config_group_type uvcg_output_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "output",
+	.children = (const struct uvcg_config_group_type*[]) {
+		&uvcg_default_output_type,
+		NULL,
+	},
+};
+
+/* -----------------------------------------------------------------------------
+ * control/terminal
+ */
+
+static const struct uvcg_config_group_type uvcg_terminal_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "terminal",
+	.children = (const struct uvcg_config_group_type*[]) {
+		&uvcg_camera_grp_type,
+		&uvcg_output_grp_type,
+		NULL,
+	},
+};
+
+/* -----------------------------------------------------------------------------
+ * control/class/{fs|ss}
+ */
+
+struct uvcg_control_class_group {
+	struct config_group group;
+	const char *name;
+};
+
+static inline struct uvc_descriptor_header
+**uvcg_get_ctl_class_arr(struct config_item *i, struct f_uvc_opts *o)
+{
+	struct uvcg_control_class_group *group =
+		container_of(i, struct uvcg_control_class_group,
+			     group.cg_item);
+
+	if (!strcmp(group->name, "fs"))
+		return o->uvc_fs_control_cls;
+
+	if (!strcmp(group->name, "ss"))
+		return o->uvc_ss_control_cls;
+
+	return NULL;
+}
+
+static int uvcg_control_class_allow_link(struct config_item *src,
+					 struct config_item *target)
+{
+	struct config_item *control, *header;
+	struct f_uvc_opts *opts;
+	struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex;
+	struct uvc_descriptor_header **class_array;
+	struct uvcg_control_header *target_hdr;
+	int ret = -EINVAL;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	control = src->ci_parent->ci_parent;
+	header = config_group_find_item(to_config_group(control), "header");
+	if (!header || target->ci_parent != header)
+		goto out;
+
+	opts = to_f_uvc_opts(control->ci_parent);
+
+	mutex_lock(&opts->lock);
+
+	class_array = uvcg_get_ctl_class_arr(src, opts);
+	if (!class_array)
+		goto unlock;
+	if (opts->refcnt || class_array[0]) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	target_hdr = to_uvcg_control_header(target);
+	++target_hdr->linked;
+	class_array[0] = (struct uvc_descriptor_header *)&target_hdr->desc;
+	ret = 0;
+
+unlock:
+	mutex_unlock(&opts->lock);
+out:
+	config_item_put(header);
+	mutex_unlock(su_mutex);
+	return ret;
+}
+
+static void uvcg_control_class_drop_link(struct config_item *src,
+					struct config_item *target)
+{
+	struct config_item *control, *header;
+	struct f_uvc_opts *opts;
+	struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex;
+	struct uvc_descriptor_header **class_array;
+	struct uvcg_control_header *target_hdr;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	control = src->ci_parent->ci_parent;
+	header = config_group_find_item(to_config_group(control), "header");
+	if (!header || target->ci_parent != header)
+		goto out;
+
+	opts = to_f_uvc_opts(control->ci_parent);
+
+	mutex_lock(&opts->lock);
+
+	class_array = uvcg_get_ctl_class_arr(src, opts);
+	if (!class_array || opts->refcnt)
+		goto unlock;
+
+	target_hdr = to_uvcg_control_header(target);
+	--target_hdr->linked;
+	class_array[0] = NULL;
+
+unlock:
+	mutex_unlock(&opts->lock);
+out:
+	config_item_put(header);
+	mutex_unlock(su_mutex);
+}
+
+static struct configfs_item_operations uvcg_control_class_item_ops = {
+	.release	= uvcg_config_item_release,
+	.allow_link	= uvcg_control_class_allow_link,
+	.drop_link	= uvcg_control_class_drop_link,
+};
+
+static const struct config_item_type uvcg_control_class_type = {
+	.ct_item_ops	= &uvcg_control_class_item_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+/* -----------------------------------------------------------------------------
+ * control/class
+ */
+
+static int uvcg_control_class_create_children(struct config_group *parent)
+{
+	static const char * const names[] = { "fs", "ss" };
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(names); ++i) {
+		struct uvcg_control_class_group *group;
+
+		group = kzalloc(sizeof(*group), GFP_KERNEL);
+		if (!group)
+			return -ENOMEM;
+
+		group->name = names[i];
+
+		config_group_init_type_name(&group->group, group->name,
+					    &uvcg_control_class_type);
+		configfs_add_default_group(&group->group, parent);
+	}
+
+	return 0;
+}
+
+static const struct uvcg_config_group_type uvcg_control_class_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "class",
+	.create_children = uvcg_control_class_create_children,
+};
+
+/* -----------------------------------------------------------------------------
+ * control
+ */
+
+static ssize_t uvcg_default_control_b_interface_number_show(
+	struct config_item *item, char *page)
+{
+	struct config_group *group = to_config_group(item);
+	struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+	struct config_item *opts_item;
+	struct f_uvc_opts *opts;
+	int result = 0;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = item->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+	result += sprintf(page, "%u\n", opts->control_interface);
+	mutex_unlock(&opts->lock);
+
+	mutex_unlock(su_mutex);
+
+	return result;
+}
+
+UVC_ATTR_RO(uvcg_default_control_, b_interface_number, bInterfaceNumber);
+
+static struct configfs_attribute *uvcg_default_control_attrs[] = {
+	&uvcg_default_control_attr_b_interface_number,
+	NULL,
+};
+
+static const struct uvcg_config_group_type uvcg_control_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_attrs	= uvcg_default_control_attrs,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "control",
+	.children = (const struct uvcg_config_group_type*[]) {
+		&uvcg_control_header_grp_type,
+		&uvcg_processing_grp_type,
+		&uvcg_terminal_grp_type,
+		&uvcg_control_class_grp_type,
+		NULL,
+	},
+};
+
+/* -----------------------------------------------------------------------------
+ * streaming/uncompressed
+ * streaming/mjpeg
+ */
+
+static const char * const uvcg_format_names[] = {
+	"uncompressed",
+	"mjpeg",
+};
+
+static ssize_t uvcg_format_bma_controls_show(struct uvcg_format *f, char *page)
+{
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct mutex *su_mutex = &f->group.cg_subsys->su_mutex;
+	int result, i;
+	char *pg = page;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = f->group.cg_item.ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+	result = sprintf(pg, "0x");
+	pg += result;
+	for (i = 0; i < UVCG_STREAMING_CONTROL_SIZE; ++i) {
+		result += sprintf(pg, "%x\n", f->bmaControls[i]);
+		pg = page + result;
+	}
+	mutex_unlock(&opts->lock);
+
+	mutex_unlock(su_mutex);
+	return result;
+}
+
+static ssize_t uvcg_format_bma_controls_store(struct uvcg_format *ch,
+					      const char *page, size_t len)
+{
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct mutex *su_mutex = &ch->group.cg_subsys->su_mutex;
+	int ret = -EINVAL;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = ch->group.cg_item.ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+	if (ch->linked || opts->refcnt) {
+		ret = -EBUSY;
+		goto end;
+	}
+
+	if (len < 4 || *page != '0' ||
+	    (*(page + 1) != 'x' && *(page + 1) != 'X'))
+		goto end;
+	ret = hex2bin(ch->bmaControls, page + 2, 1);
+	if (ret < 0)
+		goto end;
+	ret = len;
+end:
+	mutex_unlock(&opts->lock);
+	mutex_unlock(su_mutex);
+	return ret;
+}
+
+/* -----------------------------------------------------------------------------
+ * streaming/header/<NAME>
+ * streaming/header
+ */
+
+static void uvcg_format_set_indices(struct config_group *fmt);
+
+static int uvcg_streaming_header_allow_link(struct config_item *src,
+					    struct config_item *target)
+{
+	struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex;
+	struct config_item *opts_item;
+	struct f_uvc_opts *opts;
+	struct uvcg_streaming_header *src_hdr;
+	struct uvcg_format *target_fmt = NULL;
+	struct uvcg_format_ptr *format_ptr;
+	int i, ret = -EINVAL;
+
+	src_hdr = to_uvcg_streaming_header(src);
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = src->ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+
+	if (src_hdr->linked) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	/*
+	 * Linking is only allowed to direct children of the format nodes
+	 * (streaming/uncompressed or streaming/mjpeg nodes). First check that
+	 * the grand-parent of the target matches the grand-parent of the source
+	 * (the streaming node), and then verify that the target parent is a
+	 * format node.
+	 */
+	if (src->ci_parent->ci_parent != target->ci_parent->ci_parent)
+		goto out;
+
+	for (i = 0; i < ARRAY_SIZE(uvcg_format_names); ++i) {
+		if (!strcmp(target->ci_parent->ci_name, uvcg_format_names[i]))
+			break;
+	}
+
+	if (i == ARRAY_SIZE(uvcg_format_names))
+		goto out;
+
+	target_fmt = container_of(to_config_group(target), struct uvcg_format,
+				  group);
+
+	uvcg_format_set_indices(to_config_group(target));
+
+	format_ptr = kzalloc(sizeof(*format_ptr), GFP_KERNEL);
+	if (!format_ptr) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	ret = 0;
+	format_ptr->fmt = target_fmt;
+	list_add_tail(&format_ptr->entry, &src_hdr->formats);
+	++src_hdr->num_fmt;
+	++target_fmt->linked;
+
+out:
+	mutex_unlock(&opts->lock);
+	mutex_unlock(su_mutex);
+	return ret;
+}
+
+static void uvcg_streaming_header_drop_link(struct config_item *src,
+					   struct config_item *target)
+{
+	struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex;
+	struct config_item *opts_item;
+	struct f_uvc_opts *opts;
+	struct uvcg_streaming_header *src_hdr;
+	struct uvcg_format *target_fmt = NULL;
+	struct uvcg_format_ptr *format_ptr, *tmp;
+
+	src_hdr = to_uvcg_streaming_header(src);
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = src->ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+	target_fmt = container_of(to_config_group(target), struct uvcg_format,
+				  group);
+
+	list_for_each_entry_safe(format_ptr, tmp, &src_hdr->formats, entry)
+		if (format_ptr->fmt == target_fmt) {
+			list_del(&format_ptr->entry);
+			kfree(format_ptr);
+			--src_hdr->num_fmt;
+			break;
+		}
+
+	--target_fmt->linked;
+
+	mutex_unlock(&opts->lock);
+	mutex_unlock(su_mutex);
+}
+
+static struct configfs_item_operations uvcg_streaming_header_item_ops = {
+	.release	= uvcg_config_item_release,
+	.allow_link	= uvcg_streaming_header_allow_link,
+	.drop_link	= uvcg_streaming_header_drop_link,
+};
+
+#define UVCG_STREAMING_HEADER_ATTR(cname, aname, bits)			\
+static ssize_t uvcg_streaming_header_##cname##_show(			\
+	struct config_item *item, char *page)				\
+{									\
+	struct uvcg_streaming_header *sh = to_uvcg_streaming_header(item); \
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &sh->item.ci_group->cg_subsys->su_mutex;\
+	int result;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = sh->item.ci_parent->ci_parent->ci_parent;		\
+	opts = to_f_uvc_opts(opts_item);				\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", le##bits##_to_cpu(sh->desc.aname));\
+	mutex_unlock(&opts->lock);					\
+									\
+	mutex_unlock(su_mutex);						\
+	return result;							\
+}									\
+									\
+UVC_ATTR_RO(uvcg_streaming_header_, cname, aname)
+
+UVCG_STREAMING_HEADER_ATTR(bm_info, bmInfo, 8);
+UVCG_STREAMING_HEADER_ATTR(b_terminal_link, bTerminalLink, 8);
+UVCG_STREAMING_HEADER_ATTR(b_still_capture_method, bStillCaptureMethod, 8);
+UVCG_STREAMING_HEADER_ATTR(b_trigger_support, bTriggerSupport, 8);
+UVCG_STREAMING_HEADER_ATTR(b_trigger_usage, bTriggerUsage, 8);
+
+#undef UVCG_STREAMING_HEADER_ATTR
+
+static struct configfs_attribute *uvcg_streaming_header_attrs[] = {
+	&uvcg_streaming_header_attr_bm_info,
+	&uvcg_streaming_header_attr_b_terminal_link,
+	&uvcg_streaming_header_attr_b_still_capture_method,
+	&uvcg_streaming_header_attr_b_trigger_support,
+	&uvcg_streaming_header_attr_b_trigger_usage,
+	NULL,
+};
+
+static const struct config_item_type uvcg_streaming_header_type = {
+	.ct_item_ops	= &uvcg_streaming_header_item_ops,
+	.ct_attrs	= uvcg_streaming_header_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_item
+*uvcg_streaming_header_make(struct config_group *group, const char *name)
+{
+	struct uvcg_streaming_header *h;
+
+	h = kzalloc(sizeof(*h), GFP_KERNEL);
+	if (!h)
+		return ERR_PTR(-ENOMEM);
+
+	INIT_LIST_HEAD(&h->formats);
+	h->desc.bDescriptorType		= USB_DT_CS_INTERFACE;
+	h->desc.bDescriptorSubType	= UVC_VS_INPUT_HEADER;
+	h->desc.bTerminalLink		= 3;
+	h->desc.bControlSize		= UVCG_STREAMING_CONTROL_SIZE;
+
+	config_item_init_type_name(&h->item, name, &uvcg_streaming_header_type);
+
+	return &h->item;
+}
+
+static struct configfs_group_operations uvcg_streaming_header_grp_ops = {
+	.make_item		= uvcg_streaming_header_make,
+};
+
+static const struct uvcg_config_group_type uvcg_streaming_header_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_group_ops	= &uvcg_streaming_header_grp_ops,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "header",
+};
+
+/* -----------------------------------------------------------------------------
+ * streaming/<mode>/<format>/<NAME>
+ */
+
+#define UVCG_FRAME_ATTR(cname, aname, bits) \
+static ssize_t uvcg_frame_##cname##_show(struct config_item *item, char *page)\
+{									\
+	struct uvcg_frame *f = to_uvcg_frame(item);			\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &f->item.ci_group->cg_subsys->su_mutex;\
+	int result;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = f->item.ci_parent->ci_parent->ci_parent->ci_parent;	\
+	opts = to_f_uvc_opts(opts_item);				\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", f->frame.cname);			\
+	mutex_unlock(&opts->lock);					\
+									\
+	mutex_unlock(su_mutex);						\
+	return result;							\
+}									\
+									\
+static ssize_t  uvcg_frame_##cname##_store(struct config_item *item,	\
+					   const char *page, size_t len)\
+{									\
+	struct uvcg_frame *f = to_uvcg_frame(item);			\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct uvcg_format *fmt;					\
+	struct mutex *su_mutex = &f->item.ci_group->cg_subsys->su_mutex;\
+	typeof(f->frame.cname) num;					\
+	int ret;							\
+									\
+	ret = kstrtou##bits(page, 0, &num);				\
+	if (ret)							\
+		return ret;						\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = f->item.ci_parent->ci_parent->ci_parent->ci_parent;	\
+	opts = to_f_uvc_opts(opts_item);				\
+	fmt = to_uvcg_format(f->item.ci_parent);			\
+									\
+	mutex_lock(&opts->lock);					\
+	if (fmt->linked || opts->refcnt) {				\
+		ret = -EBUSY;						\
+		goto end;						\
+	}								\
+									\
+	f->frame.cname = num;						\
+	ret = len;							\
+end:									\
+	mutex_unlock(&opts->lock);					\
+	mutex_unlock(su_mutex);						\
+	return ret;							\
+}									\
+									\
+UVC_ATTR(uvcg_frame_, cname, aname);
+
+static ssize_t uvcg_frame_b_frame_index_show(struct config_item *item,
+					     char *page)
+{
+	struct uvcg_frame *f = to_uvcg_frame(item);
+	struct uvcg_format *fmt;
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct config_item *fmt_item;
+	struct mutex *su_mutex = &f->item.ci_group->cg_subsys->su_mutex;
+	int result;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	fmt_item = f->item.ci_parent;
+	fmt = to_uvcg_format(fmt_item);
+
+	if (!fmt->linked) {
+		result = -EBUSY;
+		goto out;
+	}
+
+	opts_item = fmt_item->ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+	result = sprintf(page, "%u\n", f->frame.b_frame_index);
+	mutex_unlock(&opts->lock);
+
+out:
+	mutex_unlock(su_mutex);
+	return result;
+}
+
+UVC_ATTR_RO(uvcg_frame_, b_frame_index, bFrameIndex);
+
+UVCG_FRAME_ATTR(bm_capabilities, bmCapabilities, 8);
+UVCG_FRAME_ATTR(w_width, wWidth, 16);
+UVCG_FRAME_ATTR(w_height, wHeight, 16);
+UVCG_FRAME_ATTR(dw_min_bit_rate, dwMinBitRate, 32);
+UVCG_FRAME_ATTR(dw_max_bit_rate, dwMaxBitRate, 32);
+UVCG_FRAME_ATTR(dw_max_video_frame_buffer_size, dwMaxVideoFrameBufferSize, 32);
+UVCG_FRAME_ATTR(dw_default_frame_interval, dwDefaultFrameInterval, 32);
+
+#undef UVCG_FRAME_ATTR
+
+static ssize_t uvcg_frame_dw_frame_interval_show(struct config_item *item,
+						 char *page)
+{
+	struct uvcg_frame *frm = to_uvcg_frame(item);
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct mutex *su_mutex = &frm->item.ci_group->cg_subsys->su_mutex;
+	int result, i;
+	char *pg = page;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = frm->item.ci_parent->ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+	for (result = 0, i = 0; i < frm->frame.b_frame_interval_type; ++i) {
+		result += sprintf(pg, "%u\n", frm->dw_frame_interval[i]);
+		pg = page + result;
+	}
+	mutex_unlock(&opts->lock);
+
+	mutex_unlock(su_mutex);
+	return result;
+}
+
+static inline int __uvcg_count_frm_intrv(char *buf, void *priv)
+{
+	++*((int *)priv);
+	return 0;
+}
+
+static inline int __uvcg_fill_frm_intrv(char *buf, void *priv)
+{
+	u32 num, **interv;
+	int ret;
+
+	ret = kstrtou32(buf, 0, &num);
+	if (ret)
+		return ret;
+
+	interv = priv;
+	**interv = num;
+	++*interv;
+
+	return 0;
+}
+
+static int __uvcg_iter_frm_intrv(const char *page, size_t len,
+				 int (*fun)(char *, void *), void *priv)
+{
+	/* sign, base 2 representation, newline, terminator */
+	char buf[1 + sizeof(u32) * 8 + 1 + 1];
+	const char *pg = page;
+	int i, ret;
+
+	if (!fun)
+		return -EINVAL;
+
+	while (pg - page < len) {
+		i = 0;
+		while (i < sizeof(buf) && (pg - page < len) &&
+				*pg != '\0' && *pg != '\n')
+			buf[i++] = *pg++;
+		if (i == sizeof(buf))
+			return -EINVAL;
+		while ((pg - page < len) && (*pg == '\0' || *pg == '\n'))
+			++pg;
+		buf[i] = '\0';
+		ret = fun(buf, priv);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static ssize_t uvcg_frame_dw_frame_interval_store(struct config_item *item,
+						  const char *page, size_t len)
+{
+	struct uvcg_frame *ch = to_uvcg_frame(item);
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct uvcg_format *fmt;
+	struct mutex *su_mutex = &ch->item.ci_group->cg_subsys->su_mutex;
+	int ret = 0, n = 0;
+	u32 *frm_intrv, *tmp;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = ch->item.ci_parent->ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+	fmt = to_uvcg_format(ch->item.ci_parent);
+
+	mutex_lock(&opts->lock);
+	if (fmt->linked || opts->refcnt) {
+		ret = -EBUSY;
+		goto end;
+	}
+
+	ret = __uvcg_iter_frm_intrv(page, len, __uvcg_count_frm_intrv, &n);
+	if (ret)
+		goto end;
+
+	tmp = frm_intrv = kcalloc(n, sizeof(u32), GFP_KERNEL);
+	if (!frm_intrv) {
+		ret = -ENOMEM;
+		goto end;
+	}
+
+	ret = __uvcg_iter_frm_intrv(page, len, __uvcg_fill_frm_intrv, &tmp);
+	if (ret) {
+		kfree(frm_intrv);
+		goto end;
+	}
+
+	kfree(ch->dw_frame_interval);
+	ch->dw_frame_interval = frm_intrv;
+	ch->frame.b_frame_interval_type = n;
+	sort(ch->dw_frame_interval, n, sizeof(*ch->dw_frame_interval),
+	     uvcg_config_compare_u32, NULL);
+	ret = len;
+
+end:
+	mutex_unlock(&opts->lock);
+	mutex_unlock(su_mutex);
+	return ret;
+}
+
+UVC_ATTR(uvcg_frame_, dw_frame_interval, dwFrameInterval);
+
+static struct configfs_attribute *uvcg_frame_attrs[] = {
+	&uvcg_frame_attr_b_frame_index,
+	&uvcg_frame_attr_bm_capabilities,
+	&uvcg_frame_attr_w_width,
+	&uvcg_frame_attr_w_height,
+	&uvcg_frame_attr_dw_min_bit_rate,
+	&uvcg_frame_attr_dw_max_bit_rate,
+	&uvcg_frame_attr_dw_max_video_frame_buffer_size,
+	&uvcg_frame_attr_dw_default_frame_interval,
+	&uvcg_frame_attr_dw_frame_interval,
+	NULL,
+};
+
+static const struct config_item_type uvcg_frame_type = {
+	.ct_item_ops	= &uvcg_config_item_ops,
+	.ct_attrs	= uvcg_frame_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_item *uvcg_frame_make(struct config_group *group,
+					   const char *name)
+{
+	struct uvcg_frame *h;
+	struct uvcg_format *fmt;
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct uvcg_frame_ptr *frame_ptr;
+
+	h = kzalloc(sizeof(*h), GFP_KERNEL);
+	if (!h)
+		return ERR_PTR(-ENOMEM);
+
+	h->frame.b_descriptor_type		= USB_DT_CS_INTERFACE;
+	h->frame.b_frame_index			= 1;
+	h->frame.w_width			= 640;
+	h->frame.w_height			= 360;
+	h->frame.dw_min_bit_rate		= 18432000;
+	h->frame.dw_max_bit_rate		= 55296000;
+	h->frame.dw_max_video_frame_buffer_size	= 460800;
+	h->frame.dw_default_frame_interval	= 666666;
+
+	opts_item = group->cg_item.ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+	fmt = to_uvcg_format(&group->cg_item);
+	if (fmt->type == UVCG_UNCOMPRESSED) {
+		h->frame.b_descriptor_subtype = UVC_VS_FRAME_UNCOMPRESSED;
+		h->fmt_type = UVCG_UNCOMPRESSED;
+	} else if (fmt->type == UVCG_MJPEG) {
+		h->frame.b_descriptor_subtype = UVC_VS_FRAME_MJPEG;
+		h->fmt_type = UVCG_MJPEG;
+	} else {
+		mutex_unlock(&opts->lock);
+		kfree(h);
+		return ERR_PTR(-EINVAL);
+	}
+
+	frame_ptr = kzalloc(sizeof(*frame_ptr), GFP_KERNEL);
+	if (!frame_ptr) {
+		mutex_unlock(&opts->lock);
+		kfree(h);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	frame_ptr->frm = h;
+	list_add_tail(&frame_ptr->entry, &fmt->frames);
+	++fmt->num_frames;
+	mutex_unlock(&opts->lock);
+
+	config_item_init_type_name(&h->item, name, &uvcg_frame_type);
+
+	return &h->item;
+}
+
+static void uvcg_frame_drop(struct config_group *group, struct config_item *item)
+{
+	struct uvcg_format *fmt;
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct uvcg_frame *target_frm = NULL;
+	struct uvcg_frame_ptr *frame_ptr, *tmp;
+
+	opts_item = group->cg_item.ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+	target_frm = container_of(item, struct uvcg_frame, item);
+	fmt = to_uvcg_format(&group->cg_item);
+
+	list_for_each_entry_safe(frame_ptr, tmp, &fmt->frames, entry)
+		if (frame_ptr->frm == target_frm) {
+			list_del(&frame_ptr->entry);
+			kfree(frame_ptr);
+			--fmt->num_frames;
+			break;
+		}
+	mutex_unlock(&opts->lock);
+
+	config_item_put(item);
+}
+
+static void uvcg_format_set_indices(struct config_group *fmt)
+{
+	struct config_item *ci;
+	unsigned int i = 1;
+
+	list_for_each_entry(ci, &fmt->cg_children, ci_entry) {
+		struct uvcg_frame *frm;
+
+		if (ci->ci_type != &uvcg_frame_type)
+			continue;
+
+		frm = to_uvcg_frame(ci);
+		frm->frame.b_frame_index = i++;
+	}
+}
+
+/* -----------------------------------------------------------------------------
+ * streaming/uncompressed/<NAME>
+ */
+
+static struct configfs_group_operations uvcg_uncompressed_group_ops = {
+	.make_item		= uvcg_frame_make,
+	.drop_item		= uvcg_frame_drop,
+};
+
+static ssize_t uvcg_uncompressed_guid_format_show(struct config_item *item,
+							char *page)
+{
+	struct uvcg_uncompressed *ch = to_uvcg_uncompressed(item);
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct mutex *su_mutex = &ch->fmt.group.cg_subsys->su_mutex;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = ch->fmt.group.cg_item.ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+	memcpy(page, ch->desc.guidFormat, sizeof(ch->desc.guidFormat));
+	mutex_unlock(&opts->lock);
+
+	mutex_unlock(su_mutex);
+
+	return sizeof(ch->desc.guidFormat);
+}
+
+static ssize_t uvcg_uncompressed_guid_format_store(struct config_item *item,
+						   const char *page, size_t len)
+{
+	struct uvcg_uncompressed *ch = to_uvcg_uncompressed(item);
+	struct f_uvc_opts *opts;
+	struct config_item *opts_item;
+	struct mutex *su_mutex = &ch->fmt.group.cg_subsys->su_mutex;
+	int ret;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = ch->fmt.group.cg_item.ci_parent->ci_parent->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+	if (ch->fmt.linked || opts->refcnt) {
+		ret = -EBUSY;
+		goto end;
+	}
+
+	memcpy(ch->desc.guidFormat, page,
+	       min(sizeof(ch->desc.guidFormat), len));
+	ret = sizeof(ch->desc.guidFormat);
+
+end:
+	mutex_unlock(&opts->lock);
+	mutex_unlock(su_mutex);
+	return ret;
+}
+
+UVC_ATTR(uvcg_uncompressed_, guid_format, guidFormat);
+
+#define UVCG_UNCOMPRESSED_ATTR_RO(cname, aname, bits)			\
+static ssize_t uvcg_uncompressed_##cname##_show(			\
+	struct config_item *item, char *page)				\
+{									\
+	struct uvcg_uncompressed *u = to_uvcg_uncompressed(item);	\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &u->fmt.group.cg_subsys->su_mutex;	\
+	int result;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = u->fmt.group.cg_item.ci_parent->ci_parent->ci_parent;\
+	opts = to_f_uvc_opts(opts_item);				\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", le##bits##_to_cpu(u->desc.aname));\
+	mutex_unlock(&opts->lock);					\
+									\
+	mutex_unlock(su_mutex);						\
+	return result;							\
+}									\
+									\
+UVC_ATTR_RO(uvcg_uncompressed_, cname, aname);
+
+#define UVCG_UNCOMPRESSED_ATTR(cname, aname, bits)			\
+static ssize_t uvcg_uncompressed_##cname##_show(			\
+	struct config_item *item, char *page)				\
+{									\
+	struct uvcg_uncompressed *u = to_uvcg_uncompressed(item);	\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &u->fmt.group.cg_subsys->su_mutex;	\
+	int result;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = u->fmt.group.cg_item.ci_parent->ci_parent->ci_parent;\
+	opts = to_f_uvc_opts(opts_item);				\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", le##bits##_to_cpu(u->desc.aname));\
+	mutex_unlock(&opts->lock);					\
+									\
+	mutex_unlock(su_mutex);						\
+	return result;							\
+}									\
+									\
+static ssize_t								\
+uvcg_uncompressed_##cname##_store(struct config_item *item,		\
+				    const char *page, size_t len)	\
+{									\
+	struct uvcg_uncompressed *u = to_uvcg_uncompressed(item);	\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &u->fmt.group.cg_subsys->su_mutex;	\
+	int ret;							\
+	u8 num;								\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = u->fmt.group.cg_item.ci_parent->ci_parent->ci_parent;\
+	opts = to_f_uvc_opts(opts_item);				\
+									\
+	mutex_lock(&opts->lock);					\
+	if (u->fmt.linked || opts->refcnt) {				\
+		ret = -EBUSY;						\
+		goto end;						\
+	}								\
+									\
+	ret = kstrtou8(page, 0, &num);					\
+	if (ret)							\
+		goto end;						\
+									\
+	/* index values in uvc are never 0 */				\
+	if (!num) {							\
+		ret = -EINVAL;						\
+		goto end;						\
+	}								\
+									\
+	u->desc.aname = num;						\
+	ret = len;							\
+end:									\
+	mutex_unlock(&opts->lock);					\
+	mutex_unlock(su_mutex);						\
+	return ret;							\
+}									\
+									\
+UVC_ATTR(uvcg_uncompressed_, cname, aname);
+
+UVCG_UNCOMPRESSED_ATTR_RO(b_format_index, bFormatIndex, 8);
+UVCG_UNCOMPRESSED_ATTR(b_bits_per_pixel, bBitsPerPixel, 8);
+UVCG_UNCOMPRESSED_ATTR(b_default_frame_index, bDefaultFrameIndex, 8);
+UVCG_UNCOMPRESSED_ATTR_RO(b_aspect_ratio_x, bAspectRatioX, 8);
+UVCG_UNCOMPRESSED_ATTR_RO(b_aspect_ratio_y, bAspectRatioY, 8);
+UVCG_UNCOMPRESSED_ATTR_RO(bm_interface_flags, bmInterfaceFlags, 8);
+
+#undef UVCG_UNCOMPRESSED_ATTR
+#undef UVCG_UNCOMPRESSED_ATTR_RO
+
+static inline ssize_t
+uvcg_uncompressed_bma_controls_show(struct config_item *item, char *page)
+{
+	struct uvcg_uncompressed *unc = to_uvcg_uncompressed(item);
+	return uvcg_format_bma_controls_show(&unc->fmt, page);
+}
+
+static inline ssize_t
+uvcg_uncompressed_bma_controls_store(struct config_item *item,
+				     const char *page, size_t len)
+{
+	struct uvcg_uncompressed *unc = to_uvcg_uncompressed(item);
+	return uvcg_format_bma_controls_store(&unc->fmt, page, len);
+}
+
+UVC_ATTR(uvcg_uncompressed_, bma_controls, bmaControls);
+
+static struct configfs_attribute *uvcg_uncompressed_attrs[] = {
+	&uvcg_uncompressed_attr_b_format_index,
+	&uvcg_uncompressed_attr_guid_format,
+	&uvcg_uncompressed_attr_b_bits_per_pixel,
+	&uvcg_uncompressed_attr_b_default_frame_index,
+	&uvcg_uncompressed_attr_b_aspect_ratio_x,
+	&uvcg_uncompressed_attr_b_aspect_ratio_y,
+	&uvcg_uncompressed_attr_bm_interface_flags,
+	&uvcg_uncompressed_attr_bma_controls,
+	NULL,
+};
+
+static const struct config_item_type uvcg_uncompressed_type = {
+	.ct_item_ops	= &uvcg_config_item_ops,
+	.ct_group_ops	= &uvcg_uncompressed_group_ops,
+	.ct_attrs	= uvcg_uncompressed_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_group *uvcg_uncompressed_make(struct config_group *group,
+						   const char *name)
+{
+	static char guid[] = {
+		'Y',  'U',  'Y',  '2', 0x00, 0x00, 0x10, 0x00,
+		 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71
+	};
+	struct uvcg_uncompressed *h;
+
+	h = kzalloc(sizeof(*h), GFP_KERNEL);
+	if (!h)
+		return ERR_PTR(-ENOMEM);
+
+	h->desc.bLength			= UVC_DT_FORMAT_UNCOMPRESSED_SIZE;
+	h->desc.bDescriptorType		= USB_DT_CS_INTERFACE;
+	h->desc.bDescriptorSubType	= UVC_VS_FORMAT_UNCOMPRESSED;
+	memcpy(h->desc.guidFormat, guid, sizeof(guid));
+	h->desc.bBitsPerPixel		= 16;
+	h->desc.bDefaultFrameIndex	= 1;
+	h->desc.bAspectRatioX		= 0;
+	h->desc.bAspectRatioY		= 0;
+	h->desc.bmInterfaceFlags	= 0;
+	h->desc.bCopyProtect		= 0;
+
+	INIT_LIST_HEAD(&h->fmt.frames);
+	h->fmt.type = UVCG_UNCOMPRESSED;
+	config_group_init_type_name(&h->fmt.group, name,
+				    &uvcg_uncompressed_type);
+
+	return &h->fmt.group;
+}
+
+static struct configfs_group_operations uvcg_uncompressed_grp_ops = {
+	.make_group		= uvcg_uncompressed_make,
+};
+
+static const struct uvcg_config_group_type uvcg_uncompressed_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_group_ops	= &uvcg_uncompressed_grp_ops,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "uncompressed",
+};
+
+/* -----------------------------------------------------------------------------
+ * streaming/mjpeg/<NAME>
+ */
+
+static struct configfs_group_operations uvcg_mjpeg_group_ops = {
+	.make_item		= uvcg_frame_make,
+	.drop_item		= uvcg_frame_drop,
+};
+
+#define UVCG_MJPEG_ATTR_RO(cname, aname, bits)				\
+static ssize_t uvcg_mjpeg_##cname##_show(struct config_item *item, char *page)\
+{									\
+	struct uvcg_mjpeg *u = to_uvcg_mjpeg(item);			\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &u->fmt.group.cg_subsys->su_mutex;	\
+	int result;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = u->fmt.group.cg_item.ci_parent->ci_parent->ci_parent;\
+	opts = to_f_uvc_opts(opts_item);				\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", le##bits##_to_cpu(u->desc.aname));\
+	mutex_unlock(&opts->lock);					\
+									\
+	mutex_unlock(su_mutex);						\
+	return result;							\
+}									\
+									\
+UVC_ATTR_RO(uvcg_mjpeg_, cname, aname)
+
+#define UVCG_MJPEG_ATTR(cname, aname, bits)				\
+static ssize_t uvcg_mjpeg_##cname##_show(struct config_item *item, char *page)\
+{									\
+	struct uvcg_mjpeg *u = to_uvcg_mjpeg(item);			\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &u->fmt.group.cg_subsys->su_mutex;	\
+	int result;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = u->fmt.group.cg_item.ci_parent->ci_parent->ci_parent;\
+	opts = to_f_uvc_opts(opts_item);				\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", le##bits##_to_cpu(u->desc.aname));\
+	mutex_unlock(&opts->lock);					\
+									\
+	mutex_unlock(su_mutex);						\
+	return result;							\
+}									\
+									\
+static ssize_t								\
+uvcg_mjpeg_##cname##_store(struct config_item *item,			\
+			   const char *page, size_t len)		\
+{									\
+	struct uvcg_mjpeg *u = to_uvcg_mjpeg(item);			\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &u->fmt.group.cg_subsys->su_mutex;	\
+	int ret;							\
+	u8 num;								\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = u->fmt.group.cg_item.ci_parent->ci_parent->ci_parent;\
+	opts = to_f_uvc_opts(opts_item);				\
+									\
+	mutex_lock(&opts->lock);					\
+	if (u->fmt.linked || opts->refcnt) {				\
+		ret = -EBUSY;						\
+		goto end;						\
+	}								\
+									\
+	ret = kstrtou8(page, 0, &num);					\
+	if (ret)							\
+		goto end;						\
+									\
+	/* index values in uvc are never 0 */				\
+	if (!num) {							\
+		ret = -EINVAL;						\
+		goto end;						\
+	}								\
+									\
+	u->desc.aname = num;						\
+	ret = len;							\
+end:									\
+	mutex_unlock(&opts->lock);					\
+	mutex_unlock(su_mutex);						\
+	return ret;							\
+}									\
+									\
+UVC_ATTR(uvcg_mjpeg_, cname, aname)
+
+UVCG_MJPEG_ATTR_RO(b_format_index, bFormatIndex, 8);
+UVCG_MJPEG_ATTR(b_default_frame_index, bDefaultFrameIndex, 8);
+UVCG_MJPEG_ATTR_RO(bm_flags, bmFlags, 8);
+UVCG_MJPEG_ATTR_RO(b_aspect_ratio_x, bAspectRatioX, 8);
+UVCG_MJPEG_ATTR_RO(b_aspect_ratio_y, bAspectRatioY, 8);
+UVCG_MJPEG_ATTR_RO(bm_interface_flags, bmInterfaceFlags, 8);
+
+#undef UVCG_MJPEG_ATTR
+#undef UVCG_MJPEG_ATTR_RO
+
+static inline ssize_t
+uvcg_mjpeg_bma_controls_show(struct config_item *item, char *page)
+{
+	struct uvcg_mjpeg *u = to_uvcg_mjpeg(item);
+	return uvcg_format_bma_controls_show(&u->fmt, page);
+}
+
+static inline ssize_t
+uvcg_mjpeg_bma_controls_store(struct config_item *item,
+				     const char *page, size_t len)
+{
+	struct uvcg_mjpeg *u = to_uvcg_mjpeg(item);
+	return uvcg_format_bma_controls_store(&u->fmt, page, len);
+}
+
+UVC_ATTR(uvcg_mjpeg_, bma_controls, bmaControls);
+
+static struct configfs_attribute *uvcg_mjpeg_attrs[] = {
+	&uvcg_mjpeg_attr_b_format_index,
+	&uvcg_mjpeg_attr_b_default_frame_index,
+	&uvcg_mjpeg_attr_bm_flags,
+	&uvcg_mjpeg_attr_b_aspect_ratio_x,
+	&uvcg_mjpeg_attr_b_aspect_ratio_y,
+	&uvcg_mjpeg_attr_bm_interface_flags,
+	&uvcg_mjpeg_attr_bma_controls,
+	NULL,
+};
+
+static const struct config_item_type uvcg_mjpeg_type = {
+	.ct_item_ops	= &uvcg_config_item_ops,
+	.ct_group_ops	= &uvcg_mjpeg_group_ops,
+	.ct_attrs	= uvcg_mjpeg_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_group *uvcg_mjpeg_make(struct config_group *group,
+						   const char *name)
+{
+	struct uvcg_mjpeg *h;
+
+	h = kzalloc(sizeof(*h), GFP_KERNEL);
+	if (!h)
+		return ERR_PTR(-ENOMEM);
+
+	h->desc.bLength			= UVC_DT_FORMAT_MJPEG_SIZE;
+	h->desc.bDescriptorType		= USB_DT_CS_INTERFACE;
+	h->desc.bDescriptorSubType	= UVC_VS_FORMAT_MJPEG;
+	h->desc.bDefaultFrameIndex	= 1;
+	h->desc.bAspectRatioX		= 0;
+	h->desc.bAspectRatioY		= 0;
+	h->desc.bmInterfaceFlags	= 0;
+	h->desc.bCopyProtect		= 0;
+
+	INIT_LIST_HEAD(&h->fmt.frames);
+	h->fmt.type = UVCG_MJPEG;
+	config_group_init_type_name(&h->fmt.group, name,
+				    &uvcg_mjpeg_type);
+
+	return &h->fmt.group;
+}
+
+static struct configfs_group_operations uvcg_mjpeg_grp_ops = {
+	.make_group		= uvcg_mjpeg_make,
+};
+
+static const struct uvcg_config_group_type uvcg_mjpeg_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_group_ops	= &uvcg_mjpeg_grp_ops,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "mjpeg",
+};
+
+/* -----------------------------------------------------------------------------
+ * streaming/color_matching/default
+ */
+
+#define UVCG_DEFAULT_COLOR_MATCHING_ATTR(cname, aname, bits)		\
+static ssize_t uvcg_default_color_matching_##cname##_show(		\
+	struct config_item *item, char *page)				\
+{									\
+	struct config_group *group = to_config_group(item);		\
+	struct f_uvc_opts *opts;					\
+	struct config_item *opts_item;					\
+	struct mutex *su_mutex = &group->cg_subsys->su_mutex;		\
+	struct uvc_color_matching_descriptor *cd;			\
+	int result;							\
+									\
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */	\
+									\
+	opts_item = group->cg_item.ci_parent->ci_parent->ci_parent;	\
+	opts = to_f_uvc_opts(opts_item);				\
+	cd = &opts->uvc_color_matching;					\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", le##bits##_to_cpu(cd->aname));	\
+	mutex_unlock(&opts->lock);					\
+									\
+	mutex_unlock(su_mutex);						\
+	return result;							\
+}									\
+									\
+UVC_ATTR_RO(uvcg_default_color_matching_, cname, aname)
+
+UVCG_DEFAULT_COLOR_MATCHING_ATTR(b_color_primaries, bColorPrimaries, 8);
+UVCG_DEFAULT_COLOR_MATCHING_ATTR(b_transfer_characteristics,
+				 bTransferCharacteristics, 8);
+UVCG_DEFAULT_COLOR_MATCHING_ATTR(b_matrix_coefficients, bMatrixCoefficients, 8);
+
+#undef UVCG_DEFAULT_COLOR_MATCHING_ATTR
+
+static struct configfs_attribute *uvcg_default_color_matching_attrs[] = {
+	&uvcg_default_color_matching_attr_b_color_primaries,
+	&uvcg_default_color_matching_attr_b_transfer_characteristics,
+	&uvcg_default_color_matching_attr_b_matrix_coefficients,
+	NULL,
+};
+
+static const struct uvcg_config_group_type uvcg_default_color_matching_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_attrs	= uvcg_default_color_matching_attrs,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "default",
+};
+
+/* -----------------------------------------------------------------------------
+ * streaming/color_matching
+ */
+
+static const struct uvcg_config_group_type uvcg_color_matching_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "color_matching",
+	.children = (const struct uvcg_config_group_type*[]) {
+		&uvcg_default_color_matching_type,
+		NULL,
+	},
+};
+
+/* -----------------------------------------------------------------------------
+ * streaming/class/{fs|hs|ss}
+ */
+
+struct uvcg_streaming_class_group {
+	struct config_group group;
+	const char *name;
+};
+
+static inline struct uvc_descriptor_header
+***__uvcg_get_stream_class_arr(struct config_item *i, struct f_uvc_opts *o)
+{
+	struct uvcg_streaming_class_group *group =
+		container_of(i, struct uvcg_streaming_class_group,
+			     group.cg_item);
+
+	if (!strcmp(group->name, "fs"))
+		return &o->uvc_fs_streaming_cls;
+
+	if (!strcmp(group->name, "hs"))
+		return &o->uvc_hs_streaming_cls;
+
+	if (!strcmp(group->name, "ss"))
+		return &o->uvc_ss_streaming_cls;
+
+	return NULL;
+}
+
+enum uvcg_strm_type {
+	UVCG_HEADER = 0,
+	UVCG_FORMAT,
+	UVCG_FRAME
+};
+
+/*
+ * Iterate over a hierarchy of streaming descriptors' config items.
+ * The items are created by the user with configfs.
+ *
+ * It "processes" the header pointed to by @priv1, then for each format
+ * that follows the header "processes" the format itself and then for
+ * each frame inside a format "processes" the frame.
+ *
+ * As a "processing" function the @fun is used.
+ *
+ * __uvcg_iter_strm_cls() is used in two context: first, to calculate
+ * the amount of memory needed for an array of streaming descriptors
+ * and second, to actually fill the array.
+ *
+ * @h: streaming header pointer
+ * @priv2: an "inout" parameter (the caller might want to see the changes to it)
+ * @priv3: an "inout" parameter (the caller might want to see the changes to it)
+ * @fun: callback function for processing each level of the hierarchy
+ */
+static int __uvcg_iter_strm_cls(struct uvcg_streaming_header *h,
+	void *priv2, void *priv3,
+	int (*fun)(void *, void *, void *, int, enum uvcg_strm_type type))
+{
+	struct uvcg_format_ptr *f;
+	struct config_group *grp;
+	struct config_item *item;
+	struct uvcg_frame *frm;
+	int ret, i, j;
+
+	if (!fun)
+		return -EINVAL;
+
+	i = j = 0;
+	ret = fun(h, priv2, priv3, 0, UVCG_HEADER);
+	if (ret)
+		return ret;
+	list_for_each_entry(f, &h->formats, entry) {
+		ret = fun(f->fmt, priv2, priv3, i++, UVCG_FORMAT);
+		if (ret)
+			return ret;
+		grp = &f->fmt->group;
+		list_for_each_entry(item, &grp->cg_children, ci_entry) {
+			frm = to_uvcg_frame(item);
+			ret = fun(frm, priv2, priv3, j++, UVCG_FRAME);
+			if (ret)
+				return ret;
+		}
+	}
+
+	return ret;
+}
+
+/*
+ * Count how many bytes are needed for an array of streaming descriptors.
+ *
+ * @priv1: pointer to a header, format or frame
+ * @priv2: inout parameter, accumulated size of the array
+ * @priv3: inout parameter, accumulated number of the array elements
+ * @n: unused, this function's prototype must match @fun in __uvcg_iter_strm_cls
+ */
+static int __uvcg_cnt_strm(void *priv1, void *priv2, void *priv3, int n,
+			   enum uvcg_strm_type type)
+{
+	size_t *size = priv2;
+	size_t *count = priv3;
+
+	switch (type) {
+	case UVCG_HEADER: {
+		struct uvcg_streaming_header *h = priv1;
+
+		*size += sizeof(h->desc);
+		/* bmaControls */
+		*size += h->num_fmt * UVCG_STREAMING_CONTROL_SIZE;
+	}
+	break;
+	case UVCG_FORMAT: {
+		struct uvcg_format *fmt = priv1;
+
+		if (fmt->type == UVCG_UNCOMPRESSED) {
+			struct uvcg_uncompressed *u =
+				container_of(fmt, struct uvcg_uncompressed,
+					     fmt);
+
+			*size += sizeof(u->desc);
+		} else if (fmt->type == UVCG_MJPEG) {
+			struct uvcg_mjpeg *m =
+				container_of(fmt, struct uvcg_mjpeg, fmt);
+
+			*size += sizeof(m->desc);
+		} else {
+			return -EINVAL;
+		}
+	}
+	break;
+	case UVCG_FRAME: {
+		struct uvcg_frame *frm = priv1;
+		int sz = sizeof(frm->dw_frame_interval);
+
+		*size += sizeof(frm->frame);
+		*size += frm->frame.b_frame_interval_type * sz;
+	}
+	break;
+	}
+
+	++*count;
+
+	return 0;
+}
+
+/*
+ * Fill an array of streaming descriptors.
+ *
+ * @priv1: pointer to a header, format or frame
+ * @priv2: inout parameter, pointer into a block of memory
+ * @priv3: inout parameter, pointer to a 2-dimensional array
+ */
+static int __uvcg_fill_strm(void *priv1, void *priv2, void *priv3, int n,
+			    enum uvcg_strm_type type)
+{
+	void **dest = priv2;
+	struct uvc_descriptor_header ***array = priv3;
+	size_t sz;
+
+	**array = *dest;
+	++*array;
+
+	switch (type) {
+	case UVCG_HEADER: {
+		struct uvc_input_header_descriptor *ihdr = *dest;
+		struct uvcg_streaming_header *h = priv1;
+		struct uvcg_format_ptr *f;
+
+		memcpy(*dest, &h->desc, sizeof(h->desc));
+		*dest += sizeof(h->desc);
+		sz = UVCG_STREAMING_CONTROL_SIZE;
+		list_for_each_entry(f, &h->formats, entry) {
+			memcpy(*dest, f->fmt->bmaControls, sz);
+			*dest += sz;
+		}
+		ihdr->bLength = sizeof(h->desc) + h->num_fmt * sz;
+		ihdr->bNumFormats = h->num_fmt;
+	}
+	break;
+	case UVCG_FORMAT: {
+		struct uvcg_format *fmt = priv1;
+
+		if (fmt->type == UVCG_UNCOMPRESSED) {
+			struct uvcg_uncompressed *u =
+				container_of(fmt, struct uvcg_uncompressed,
+					     fmt);
+
+			u->desc.bFormatIndex = n + 1;
+			u->desc.bNumFrameDescriptors = fmt->num_frames;
+			memcpy(*dest, &u->desc, sizeof(u->desc));
+			*dest += sizeof(u->desc);
+		} else if (fmt->type == UVCG_MJPEG) {
+			struct uvcg_mjpeg *m =
+				container_of(fmt, struct uvcg_mjpeg, fmt);
+
+			m->desc.bFormatIndex = n + 1;
+			m->desc.bNumFrameDescriptors = fmt->num_frames;
+			memcpy(*dest, &m->desc, sizeof(m->desc));
+			*dest += sizeof(m->desc);
+		} else {
+			return -EINVAL;
+		}
+	}
+	break;
+	case UVCG_FRAME: {
+		struct uvcg_frame *frm = priv1;
+		struct uvc_descriptor_header *h = *dest;
+
+		sz = sizeof(frm->frame);
+		memcpy(*dest, &frm->frame, sz);
+		*dest += sz;
+		sz = frm->frame.b_frame_interval_type *
+			sizeof(*frm->dw_frame_interval);
+		memcpy(*dest, frm->dw_frame_interval, sz);
+		*dest += sz;
+		if (frm->fmt_type == UVCG_UNCOMPRESSED)
+			h->bLength = UVC_DT_FRAME_UNCOMPRESSED_SIZE(
+				frm->frame.b_frame_interval_type);
+		else if (frm->fmt_type == UVCG_MJPEG)
+			h->bLength = UVC_DT_FRAME_MJPEG_SIZE(
+				frm->frame.b_frame_interval_type);
+	}
+	break;
+	}
+
+	return 0;
+}
+
+static int uvcg_streaming_class_allow_link(struct config_item *src,
+					   struct config_item *target)
+{
+	struct config_item *streaming, *header;
+	struct f_uvc_opts *opts;
+	struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex;
+	struct uvc_descriptor_header ***class_array, **cl_arr;
+	struct uvcg_streaming_header *target_hdr;
+	void *data, *data_save;
+	size_t size = 0, count = 0;
+	int ret = -EINVAL;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	streaming = src->ci_parent->ci_parent;
+	header = config_group_find_item(to_config_group(streaming), "header");
+	if (!header || target->ci_parent != header)
+		goto out;
+
+	opts = to_f_uvc_opts(streaming->ci_parent);
+
+	mutex_lock(&opts->lock);
+
+	class_array = __uvcg_get_stream_class_arr(src, opts);
+	if (!class_array || *class_array || opts->refcnt) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	target_hdr = to_uvcg_streaming_header(target);
+	ret = __uvcg_iter_strm_cls(target_hdr, &size, &count, __uvcg_cnt_strm);
+	if (ret)
+		goto unlock;
+
+	count += 2; /* color_matching, NULL */
+	*class_array = kcalloc(count, sizeof(void *), GFP_KERNEL);
+	if (!*class_array) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	data = data_save = kzalloc(size, GFP_KERNEL);
+	if (!data) {
+		kfree(*class_array);
+		*class_array = NULL;
+		ret = -ENOMEM;
+		goto unlock;
+	}
+	cl_arr = *class_array;
+	ret = __uvcg_iter_strm_cls(target_hdr, &data, &cl_arr,
+				   __uvcg_fill_strm);
+	if (ret) {
+		kfree(*class_array);
+		*class_array = NULL;
+		/*
+		 * __uvcg_fill_strm() called from __uvcg_iter_stream_cls()
+		 * might have advanced the "data", so use a backup copy
+		 */
+		kfree(data_save);
+		goto unlock;
+	}
+	*cl_arr = (struct uvc_descriptor_header *)&opts->uvc_color_matching;
+
+	++target_hdr->linked;
+	ret = 0;
+
+unlock:
+	mutex_unlock(&opts->lock);
+out:
+	config_item_put(header);
+	mutex_unlock(su_mutex);
+	return ret;
+}
+
+static void uvcg_streaming_class_drop_link(struct config_item *src,
+					  struct config_item *target)
+{
+	struct config_item *streaming, *header;
+	struct f_uvc_opts *opts;
+	struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex;
+	struct uvc_descriptor_header ***class_array;
+	struct uvcg_streaming_header *target_hdr;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	streaming = src->ci_parent->ci_parent;
+	header = config_group_find_item(to_config_group(streaming), "header");
+	if (!header || target->ci_parent != header)
+		goto out;
+
+	opts = to_f_uvc_opts(streaming->ci_parent);
+
+	mutex_lock(&opts->lock);
+
+	class_array = __uvcg_get_stream_class_arr(src, opts);
+	if (!class_array || !*class_array)
+		goto unlock;
+
+	if (opts->refcnt)
+		goto unlock;
+
+	target_hdr = to_uvcg_streaming_header(target);
+	--target_hdr->linked;
+	kfree(**class_array);
+	kfree(*class_array);
+	*class_array = NULL;
+
+unlock:
+	mutex_unlock(&opts->lock);
+out:
+	config_item_put(header);
+	mutex_unlock(su_mutex);
+}
+
+static struct configfs_item_operations uvcg_streaming_class_item_ops = {
+	.release	= uvcg_config_item_release,
+	.allow_link	= uvcg_streaming_class_allow_link,
+	.drop_link	= uvcg_streaming_class_drop_link,
+};
+
+static const struct config_item_type uvcg_streaming_class_type = {
+	.ct_item_ops	= &uvcg_streaming_class_item_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+/* -----------------------------------------------------------------------------
+ * streaming/class
+ */
+
+static int uvcg_streaming_class_create_children(struct config_group *parent)
+{
+	static const char * const names[] = { "fs", "hs", "ss" };
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(names); ++i) {
+		struct uvcg_streaming_class_group *group;
+
+		group = kzalloc(sizeof(*group), GFP_KERNEL);
+		if (!group)
+			return -ENOMEM;
+
+		group->name = names[i];
+
+		config_group_init_type_name(&group->group, group->name,
+					    &uvcg_streaming_class_type);
+		configfs_add_default_group(&group->group, parent);
+	}
+
+	return 0;
+}
+
+static const struct uvcg_config_group_type uvcg_streaming_class_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "class",
+	.create_children = uvcg_streaming_class_create_children,
+};
+
+/* -----------------------------------------------------------------------------
+ * streaming
+ */
+
+static ssize_t uvcg_default_streaming_b_interface_number_show(
+	struct config_item *item, char *page)
+{
+	struct config_group *group = to_config_group(item);
+	struct mutex *su_mutex = &group->cg_subsys->su_mutex;
+	struct config_item *opts_item;
+	struct f_uvc_opts *opts;
+	int result = 0;
+
+	mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+	opts_item = item->ci_parent;
+	opts = to_f_uvc_opts(opts_item);
+
+	mutex_lock(&opts->lock);
+	result += sprintf(page, "%u\n", opts->streaming_interface);
+	mutex_unlock(&opts->lock);
+
+	mutex_unlock(su_mutex);
+
+	return result;
+}
+
+UVC_ATTR_RO(uvcg_default_streaming_, b_interface_number, bInterfaceNumber);
+
+static struct configfs_attribute *uvcg_default_streaming_attrs[] = {
+	&uvcg_default_streaming_attr_b_interface_number,
+	NULL,
+};
+
+static const struct uvcg_config_group_type uvcg_streaming_grp_type = {
+	.type = {
+		.ct_item_ops	= &uvcg_config_item_ops,
+		.ct_attrs	= uvcg_default_streaming_attrs,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "streaming",
+	.children = (const struct uvcg_config_group_type*[]) {
+		&uvcg_streaming_header_grp_type,
+		&uvcg_uncompressed_grp_type,
+		&uvcg_mjpeg_grp_type,
+		&uvcg_color_matching_grp_type,
+		&uvcg_streaming_class_grp_type,
+		NULL,
+	},
+};
+
+/* -----------------------------------------------------------------------------
+ * UVC function
+ */
+
+static void uvc_func_item_release(struct config_item *item)
+{
+	struct f_uvc_opts *opts = to_f_uvc_opts(item);
+
+	uvcg_config_remove_children(to_config_group(item));
+	usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations uvc_func_item_ops = {
+	.release	= uvc_func_item_release,
+};
+
+#define UVCG_OPTS_ATTR(cname, aname, limit)				\
+static ssize_t f_uvc_opts_##cname##_show(				\
+	struct config_item *item, char *page)				\
+{									\
+	struct f_uvc_opts *opts = to_f_uvc_opts(item);			\
+	int result;							\
+									\
+	mutex_lock(&opts->lock);					\
+	result = sprintf(page, "%u\n", opts->cname);			\
+	mutex_unlock(&opts->lock);					\
+									\
+	return result;							\
+}									\
+									\
+static ssize_t								\
+f_uvc_opts_##cname##_store(struct config_item *item,			\
+			   const char *page, size_t len)		\
+{									\
+	struct f_uvc_opts *opts = to_f_uvc_opts(item);			\
+	unsigned int num;						\
+	int ret;							\
+									\
+	mutex_lock(&opts->lock);					\
+	if (opts->refcnt) {						\
+		ret = -EBUSY;						\
+		goto end;						\
+	}								\
+									\
+	ret = kstrtouint(page, 0, &num);				\
+	if (ret)							\
+		goto end;						\
+									\
+	if (num > limit) {						\
+		ret = -EINVAL;						\
+		goto end;						\
+	}								\
+	opts->cname = num;						\
+	ret = len;							\
+end:									\
+	mutex_unlock(&opts->lock);					\
+	return ret;							\
+}									\
+									\
+UVC_ATTR(f_uvc_opts_, cname, cname)
+
+UVCG_OPTS_ATTR(streaming_interval, streaming_interval, 16);
+UVCG_OPTS_ATTR(streaming_maxpacket, streaming_maxpacket, 3072);
+UVCG_OPTS_ATTR(streaming_maxburst, streaming_maxburst, 15);
+
+#undef UVCG_OPTS_ATTR
+
+#define UVCG_OPTS_STRING_ATTR(cname, aname)				\
+static ssize_t f_uvc_opts_string_##cname##_show(struct config_item *item,\
+					 char *page)			\
+{									\
+	struct f_uvc_opts *opts = to_f_uvc_opts(item);			\
+	int result;							\
+									\
+	mutex_lock(&opts->lock);					\
+	result = snprintf(page, sizeof(opts->aname), "%s", opts->aname);\
+	mutex_unlock(&opts->lock);					\
+									\
+	return result;							\
+}									\
+									\
+static ssize_t f_uvc_opts_string_##cname##_store(struct config_item *item,\
+					  const char *page, size_t len)	\
+{									\
+	struct f_uvc_opts *opts = to_f_uvc_opts(item);			\
+	int size = min(sizeof(opts->aname), len + 1);			\
+	int ret = 0;							\
+									\
+	mutex_lock(&opts->lock);					\
+	if (opts->refcnt) {						\
+		ret = -EBUSY;						\
+		goto end;						\
+	}								\
+									\
+	ret = strscpy(opts->aname, page, size);				\
+	if (ret == -E2BIG)						\
+		ret = size - 1;						\
+									\
+end:									\
+	mutex_unlock(&opts->lock);					\
+	return ret;							\
+}									\
+									\
+UVC_ATTR(f_uvc_opts_string_, cname, aname)
+
+UVCG_OPTS_STRING_ATTR(function_name, function_name);
+
+#undef UVCG_OPTS_STRING_ATTR
+
+static struct configfs_attribute *uvc_attrs[] = {
+	&f_uvc_opts_attr_streaming_interval,
+	&f_uvc_opts_attr_streaming_maxpacket,
+	&f_uvc_opts_attr_streaming_maxburst,
+	&f_uvc_opts_string_attr_function_name,
+	NULL,
+};
+
+static const struct uvcg_config_group_type uvc_func_type = {
+	.type = {
+		.ct_item_ops	= &uvc_func_item_ops,
+		.ct_attrs	= uvc_attrs,
+		.ct_owner	= THIS_MODULE,
+	},
+	.name = "",
+	.children = (const struct uvcg_config_group_type*[]) {
+		&uvcg_control_grp_type,
+		&uvcg_streaming_grp_type,
+		NULL,
+	},
+};
+
+int uvcg_attach_configfs(struct f_uvc_opts *opts)
+{
+	int ret;
+
+	config_group_init_type_name(&opts->func_inst.group, uvc_func_type.name,
+				    &uvc_func_type.type);
+
+	ret = uvcg_config_create_children(&opts->func_inst.group,
+					  &uvc_func_type);
+	if (ret < 0)
+		config_group_put(&opts->func_inst.group);
+
+	return ret;
+}