// SPDX-License-Identifier: GPL-2.0
#include <linux/configfs.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/kstrtox.h>
#include <linux/nls.h>
#include <linux/usb/composite.h>
#include <linux/usb/func_utils.h>
#include <linux/usb/gadget_configfs.h>
#include <linux/usb/webusb.h>
#include "configfs.h"
#include "u_os_desc.h"

static int check_user_usb_string(const char *name,
                struct usb_gadget_strings *stringtab_dev)
{
        u16 num;
        int ret;

        ret = kstrtou16(name, 0, &num);
        if (ret)
                return ret;

        if (!usb_validate_langid(num))
                return -EINVAL;

        stringtab_dev->language = num;
        return 0;
}

#define MAX_NAME_LEN    40
#define MAX_USB_STRING_LANGS 2

static const struct usb_descriptor_header *otg_desc[2];

struct gadget_info {
        struct config_group group;
        struct config_group functions_group;
        struct config_group configs_group;
        struct config_group strings_group;
        struct config_group os_desc_group;
        struct config_group webusb_group;

        struct mutex lock;
        struct usb_gadget_strings *gstrings[MAX_USB_STRING_LANGS + 1];
        struct list_head string_list;
        struct list_head available_func;

        struct usb_composite_driver composite;
        struct usb_composite_dev cdev;
        bool use_os_desc;
        char b_vendor_code;
        char qw_sign[OS_STRING_QW_SIGN_LEN];
        bool use_webusb;
        u16 bcd_webusb_version;
        u8 b_webusb_vendor_code;
        char landing_page[WEBUSB_URL_RAW_MAX_LENGTH];

        spinlock_t spinlock;
        bool unbind;
};

static inline struct gadget_info *to_gadget_info(struct config_item *item)
{
        return container_of(to_config_group(item), struct gadget_info, group);
}

struct config_usb_cfg {
        struct config_group group;
        struct config_group strings_group;
        struct list_head string_list;
        struct usb_configuration c;
        struct list_head func_list;
        struct usb_gadget_strings *gstrings[MAX_USB_STRING_LANGS + 1];
};

static inline struct config_usb_cfg *to_config_usb_cfg(struct config_item *item)
{
        return container_of(to_config_group(item), struct config_usb_cfg,
                        group);
}

static inline struct gadget_info *cfg_to_gadget_info(struct config_usb_cfg *cfg)
{
        return container_of(cfg->c.cdev, struct gadget_info, cdev);
}

struct gadget_language {
        struct usb_gadget_strings stringtab_dev;
        struct usb_string strings[USB_GADGET_FIRST_AVAIL_IDX];
        char *manufacturer;
        char *product;
        char *serialnumber;

        struct config_group group;
        struct list_head list;
        struct list_head gadget_strings;
        unsigned int nstrings;
};

struct gadget_config_name {
        struct usb_gadget_strings stringtab_dev;
        struct usb_string strings;
        char *configuration;

        struct config_group group;
        struct list_head list;
};

#define USB_MAX_STRING_WITH_NULL_LEN    (USB_MAX_STRING_LEN+1)

static int usb_string_copy(const char *s, char **s_copy)
{
        int ret;
        char *str;
        char *copy = *s_copy;

        ret = strlen(s);
        if (ret > USB_MAX_STRING_LEN)
                return -EOVERFLOW;
        if (ret < 1)
                return -EINVAL;

        if (copy) {
                str = copy;
        } else {
                str = kmalloc(USB_MAX_STRING_WITH_NULL_LEN, GFP_KERNEL);
                if (!str)
                        return -ENOMEM;
        }
        strcpy(str, s);
        if (str[ret - 1] == '\n')
                str[ret - 1] = '\0';
        *s_copy = str;
        return 0;
}

#define GI_DEVICE_DESC_SIMPLE_R_u8(__name)      \
static ssize_t gadget_dev_desc_##__name##_show(struct config_item *item, \
                        char *page)     \
{       \
        return sprintf(page, "0x%02x\n", \
                to_gadget_info(item)->cdev.desc.__name); \
}

#define GI_DEVICE_DESC_SIMPLE_R_u16(__name)     \
static ssize_t gadget_dev_desc_##__name##_show(struct config_item *item, \
                        char *page)     \
{       \
        return sprintf(page, "0x%04x\n", \
                le16_to_cpup(&to_gadget_info(item)->cdev.desc.__name)); \
}


#define GI_DEVICE_DESC_SIMPLE_W_u8(_name)               \
static ssize_t gadget_dev_desc_##_name##_store(struct config_item *item, \
                const char *page, size_t len)           \
{                                                       \
        u8 val;                                         \
        int ret;                                        \
        ret = kstrtou8(page, 0, &val);                  \
        if (ret)                                        \
                return ret;                             \
        to_gadget_info(item)->cdev.desc._name = val;    \
        return len;                                     \
}

#define GI_DEVICE_DESC_SIMPLE_W_u16(_name)      \
static ssize_t gadget_dev_desc_##_name##_store(struct config_item *item, \
                const char *page, size_t len)           \
{                                                       \
        u16 val;                                        \
        int ret;                                        \
        ret = kstrtou16(page, 0, &val);                 \
        if (ret)                                        \
                return ret;                             \
        to_gadget_info(item)->cdev.desc._name = cpu_to_le16p(&val);     \
        return len;                                     \
}

#define GI_DEVICE_DESC_SIMPLE_RW(_name, _type)  \
        GI_DEVICE_DESC_SIMPLE_R_##_type(_name)  \
        GI_DEVICE_DESC_SIMPLE_W_##_type(_name)

GI_DEVICE_DESC_SIMPLE_R_u16(bcdUSB);
GI_DEVICE_DESC_SIMPLE_RW(bDeviceClass, u8);
GI_DEVICE_DESC_SIMPLE_RW(bDeviceSubClass, u8);
GI_DEVICE_DESC_SIMPLE_RW(bDeviceProtocol, u8);
GI_DEVICE_DESC_SIMPLE_RW(bMaxPacketSize0, u8);
GI_DEVICE_DESC_SIMPLE_RW(idVendor, u16);
GI_DEVICE_DESC_SIMPLE_RW(idProduct, u16);
GI_DEVICE_DESC_SIMPLE_R_u16(bcdDevice);

static ssize_t is_valid_bcd(u16 bcd_val)
{
        if ((bcd_val & 0xf) > 9)
                return -EINVAL;
        if (((bcd_val >> 4) & 0xf) > 9)
                return -EINVAL;
        if (((bcd_val >> 8) & 0xf) > 9)
                return -EINVAL;
        if (((bcd_val >> 12) & 0xf) > 9)
                return -EINVAL;
        return 0;
}

static ssize_t gadget_dev_desc_bcdDevice_store(struct config_item *item,
                const char *page, size_t len)
{
        u16 bcdDevice;
        int ret;

        ret = kstrtou16(page, 0, &bcdDevice);
        if (ret)
                return ret;
        ret = is_valid_bcd(bcdDevice);
        if (ret)
                return ret;

        to_gadget_info(item)->cdev.desc.bcdDevice = cpu_to_le16(bcdDevice);
        return len;
}

static ssize_t gadget_dev_desc_bcdUSB_store(struct config_item *item,
                const char *page, size_t len)
{
        u16 bcdUSB;
        int ret;

        ret = kstrtou16(page, 0, &bcdUSB);
        if (ret)
                return ret;
        ret = is_valid_bcd(bcdUSB);
        if (ret)
                return ret;

        to_gadget_info(item)->cdev.desc.bcdUSB = cpu_to_le16(bcdUSB);
        return len;
}

static ssize_t gadget_dev_desc_UDC_show(struct config_item *item, char *page)
{
        struct gadget_info *gi = to_gadget_info(item);
        char *udc_name;
        int ret;

        mutex_lock(&gi->lock);
        udc_name = gi->composite.gadget_driver.udc_name;
        ret = sprintf(page, "%s\n", udc_name ?: "");
        mutex_unlock(&gi->lock);

        return ret;
}

static int unregister_gadget(struct gadget_info *gi)
{
        int ret;

        if (!gi->composite.gadget_driver.udc_name)
                return -ENODEV;

        ret = usb_gadget_unregister_driver(&gi->composite.gadget_driver);
        if (ret)
                return ret;
        kfree(gi->composite.gadget_driver.udc_name);
        gi->composite.gadget_driver.udc_name = NULL;
        return 0;
}

static ssize_t gadget_dev_desc_UDC_store(struct config_item *item,
                const char *page, size_t len)
{
        struct gadget_info *gi = to_gadget_info(item);
        char *name;
        int ret;

        if (strlen(page) < len)
                return -EOVERFLOW;

        name = kstrdup(page, GFP_KERNEL);
        if (!name)
                return -ENOMEM;
        if (name[len - 1] == '\n')
                name[len - 1] = '\0';

        mutex_lock(&gi->lock);

        if (!strlen(name)) {
                ret = unregister_gadget(gi);
                if (ret)
                        goto err;
                kfree(name);
        } else {
                if (gi->composite.gadget_driver.udc_name) {
                        ret = -EBUSY;
                        goto err;
                }
                gi->composite.gadget_driver.udc_name = name;
                ret = usb_gadget_register_driver(&gi->composite.gadget_driver);
                if (ret) {
                        gi->composite.gadget_driver.udc_name = NULL;
                        goto err;
                }
        }
        mutex_unlock(&gi->lock);
        return len;
err:
        kfree(name);
        mutex_unlock(&gi->lock);
        return ret;
}

static ssize_t gadget_dev_desc_max_speed_show(struct config_item *item,
                                              char *page)
{
        enum usb_device_speed speed = to_gadget_info(item)->composite.max_speed;

        return sprintf(page, "%s\n", usb_speed_string(speed));
}

static ssize_t gadget_dev_desc_max_speed_store(struct config_item *item,
                                               const char *page, size_t len)
{
        struct gadget_info *gi = to_gadget_info(item);

        mutex_lock(&gi->lock);

        /* Prevent changing of max_speed after the driver is binded */
        if (gi->composite.gadget_driver.udc_name)
                goto err;

        if (strncmp(page, "super-speed-plus", 16) == 0)
                gi->composite.max_speed = USB_SPEED_SUPER_PLUS;
        else if (strncmp(page, "super-speed", 11) == 0)
                gi->composite.max_speed = USB_SPEED_SUPER;
        else if (strncmp(page, "high-speed", 10) == 0)
                gi->composite.max_speed = USB_SPEED_HIGH;
        else if (strncmp(page, "full-speed", 10) == 0)
                gi->composite.max_speed = USB_SPEED_FULL;
        else if (strncmp(page, "low-speed", 9) == 0)
                gi->composite.max_speed = USB_SPEED_LOW;
        else
                goto err;

        gi->composite.gadget_driver.max_speed = gi->composite.max_speed;

        mutex_unlock(&gi->lock);
        return len;
err:
        mutex_unlock(&gi->lock);
        return -EINVAL;
}

CONFIGFS_ATTR(gadget_dev_desc_, bDeviceClass);
CONFIGFS_ATTR(gadget_dev_desc_, bDeviceSubClass);
CONFIGFS_ATTR(gadget_dev_desc_, bDeviceProtocol);
CONFIGFS_ATTR(gadget_dev_desc_, bMaxPacketSize0);
CONFIGFS_ATTR(gadget_dev_desc_, idVendor);
CONFIGFS_ATTR(gadget_dev_desc_, idProduct);
CONFIGFS_ATTR(gadget_dev_desc_, bcdDevice);
CONFIGFS_ATTR(gadget_dev_desc_, bcdUSB);
CONFIGFS_ATTR(gadget_dev_desc_, UDC);
CONFIGFS_ATTR(gadget_dev_desc_, max_speed);

static struct configfs_attribute *gadget_root_attrs[] = {
        &gadget_dev_desc_attr_bDeviceClass,
        &gadget_dev_desc_attr_bDeviceSubClass,
        &gadget_dev_desc_attr_bDeviceProtocol,
        &gadget_dev_desc_attr_bMaxPacketSize0,
        &gadget_dev_desc_attr_idVendor,
        &gadget_dev_desc_attr_idProduct,
        &gadget_dev_desc_attr_bcdDevice,
        &gadget_dev_desc_attr_bcdUSB,
        &gadget_dev_desc_attr_UDC,
        &gadget_dev_desc_attr_max_speed,
        NULL,
};

static inline struct gadget_language *to_gadget_language(struct config_item *item)
{
        return container_of(to_config_group(item), struct gadget_language,
                         group);
}

static inline struct gadget_config_name *to_gadget_config_name(
                struct config_item *item)
{
        return container_of(to_config_group(item), struct gadget_config_name,
                         group);
}

static inline struct usb_function_instance *to_usb_function_instance(
                struct config_item *item)
{
        return container_of(to_config_group(item),
                         struct usb_function_instance, group);
}

static void gadget_info_attr_release(struct config_item *item)
{
        struct gadget_info *gi = to_gadget_info(item);

        WARN_ON(!list_empty(&gi->cdev.configs));
        WARN_ON(!list_empty(&gi->string_list));
        WARN_ON(!list_empty(&gi->available_func));
        kfree(gi->composite.gadget_driver.function);
        kfree(gi->composite.gadget_driver.driver.name);
        kfree(gi);
}

static const struct configfs_item_operations gadget_root_item_ops = {
        .release                = gadget_info_attr_release,
};

static void gadget_config_attr_release(struct config_item *item)
{
        struct config_usb_cfg *cfg = to_config_usb_cfg(item);

        WARN_ON(!list_empty(&cfg->c.functions));
        list_del(&cfg->c.list);
        kfree(cfg->c.label);
        kfree(cfg);
}

static int config_usb_cfg_link(
        struct config_item *usb_cfg_ci,
        struct config_item *usb_func_ci)
{
        struct config_usb_cfg *cfg = to_config_usb_cfg(usb_cfg_ci);
        struct gadget_info *gi = cfg_to_gadget_info(cfg);

        struct usb_function_instance *fi =
                        to_usb_function_instance(usb_func_ci);
        struct usb_function_instance *a_fi = NULL, *iter;
        struct usb_function *f;
        int ret;

        mutex_lock(&gi->lock);
        /*
         * Make sure this function is from within our _this_ gadget and not
         * from another gadget or a random directory.
         * Also a function instance can only be linked once.
         */

        if (gi->composite.gadget_driver.udc_name) {
                ret = -EINVAL;
                goto out;
        }

        list_for_each_entry(iter, &gi->available_func, cfs_list) {
                if (iter != fi)
                        continue;
                a_fi = iter;
                break;
        }
        if (!a_fi) {
                ret = -EINVAL;
                goto out;
        }

        list_for_each_entry(f, &cfg->func_list, list) {
                if (f->fi == fi) {
                        ret = -EEXIST;
                        goto out;
                }
        }

        f = usb_get_function(fi);
        if (IS_ERR(f)) {
                ret = PTR_ERR(f);
                goto out;
        }

        /* stash the function until we bind it to the gadget */
        list_add_tail(&f->list, &cfg->func_list);
        ret = 0;
out:
        mutex_unlock(&gi->lock);
        return ret;
}

static void config_usb_cfg_unlink(
        struct config_item *usb_cfg_ci,
        struct config_item *usb_func_ci)
{
        struct config_usb_cfg *cfg = to_config_usb_cfg(usb_cfg_ci);
        struct gadget_info *gi = cfg_to_gadget_info(cfg);

        struct usb_function_instance *fi =
                        to_usb_function_instance(usb_func_ci);
        struct usb_function *f;

        /*
         * ideally I would like to forbid to unlink functions while a gadget is
         * bound to an UDC. Since this isn't possible at the moment, we simply
         * force an unbind, the function is available here and then we can
         * remove the function.
         */
        mutex_lock(&gi->lock);
        if (gi->composite.gadget_driver.udc_name)
                unregister_gadget(gi);
        WARN_ON(gi->composite.gadget_driver.udc_name);

        list_for_each_entry(f, &cfg->func_list, list) {
                if (f->fi == fi) {
                        list_del(&f->list);
                        usb_put_function(f);
                        mutex_unlock(&gi->lock);
                        return;
                }
        }
        mutex_unlock(&gi->lock);
        WARN(1, "Unable to locate function to unbind\n");
}

static const struct configfs_item_operations gadget_config_item_ops = {
        .release                = gadget_config_attr_release,
        .allow_link             = config_usb_cfg_link,
        .drop_link              = config_usb_cfg_unlink,
};


static ssize_t gadget_config_desc_MaxPower_show(struct config_item *item,
                char *page)
{
        struct config_usb_cfg *cfg = to_config_usb_cfg(item);

        return sprintf(page, "%u\n", cfg->c.MaxPower);
}

static ssize_t gadget_config_desc_MaxPower_store(struct config_item *item,
                const char *page, size_t len)
{
        struct config_usb_cfg *cfg = to_config_usb_cfg(item);
        u16 val;
        int ret;
        ret = kstrtou16(page, 0, &val);
        if (ret)
                return ret;
        if (DIV_ROUND_UP(val, 8) > 0xff)
                return -ERANGE;
        cfg->c.MaxPower = val;
        return len;
}

static ssize_t gadget_config_desc_bmAttributes_show(struct config_item *item,
                char *page)
{
        struct config_usb_cfg *cfg = to_config_usb_cfg(item);

        return sprintf(page, "0x%02x\n", cfg->c.bmAttributes);
}

static ssize_t gadget_config_desc_bmAttributes_store(struct config_item *item,
                const char *page, size_t len)
{
        struct config_usb_cfg *cfg = to_config_usb_cfg(item);
        u8 val;
        int ret;
        ret = kstrtou8(page, 0, &val);
        if (ret)
                return ret;
        if (!(val & USB_CONFIG_ATT_ONE))
                return -EINVAL;
        if (val & ~(USB_CONFIG_ATT_ONE | USB_CONFIG_ATT_SELFPOWER |
                                USB_CONFIG_ATT_WAKEUP))
                return -EINVAL;
        cfg->c.bmAttributes = val;
        return len;
}

CONFIGFS_ATTR(gadget_config_desc_, MaxPower);
CONFIGFS_ATTR(gadget_config_desc_, bmAttributes);

static struct configfs_attribute *gadget_config_attrs[] = {
        &gadget_config_desc_attr_MaxPower,
        &gadget_config_desc_attr_bmAttributes,
        NULL,
};

static const struct config_item_type gadget_config_type = {
        .ct_item_ops    = &gadget_config_item_ops,
        .ct_attrs       = gadget_config_attrs,
        .ct_owner       = THIS_MODULE,
};

static const struct config_item_type gadget_root_type = {
        .ct_item_ops    = &gadget_root_item_ops,
        .ct_attrs       = gadget_root_attrs,
        .ct_owner       = THIS_MODULE,
};

static void composite_init_dev(struct usb_composite_dev *cdev)
{
        spin_lock_init(&cdev->lock);
        INIT_LIST_HEAD(&cdev->configs);
        INIT_LIST_HEAD(&cdev->gstrings);
}

static struct config_group *function_make(
                struct config_group *group,
                const char *name)
{
        struct gadget_info *gi;
        struct usb_function_instance *fi;
        char buf[MAX_NAME_LEN];
        char *func_name;
        char *instance_name;
        int ret;

        if (strlen(name) >= MAX_NAME_LEN)
                return ERR_PTR(-ENAMETOOLONG);

        scnprintf(buf, MAX_NAME_LEN, "%s", name);

        func_name = buf;
        instance_name = strchr(func_name, '.');
        if (!instance_name) {
                pr_err("Unable to locate . in FUNC.INSTANCE\n");
                return ERR_PTR(-EINVAL);
        }
        *instance_name = '\0';
        instance_name++;

        fi = usb_get_function_instance(func_name);
        if (IS_ERR(fi))
                return ERR_CAST(fi);

        ret = config_item_set_name(&fi->group.cg_item, "%s", name);
        if (ret) {
                usb_put_function_instance(fi);
                return ERR_PTR(ret);
        }
        if (fi->set_inst_name) {
                ret = fi->set_inst_name(fi, instance_name);
                if (ret) {
                        usb_put_function_instance(fi);
                        return ERR_PTR(ret);
                }
        }

        gi = container_of(group, struct gadget_info, functions_group);

        mutex_lock(&gi->lock);
        list_add_tail(&fi->cfs_list, &gi->available_func);
        mutex_unlock(&gi->lock);
        return &fi->group;
}

static void function_drop(
                struct config_group *group,
                struct config_item *item)
{
        struct usb_function_instance *fi = to_usb_function_instance(item);
        struct gadget_info *gi;

        gi = container_of(group, struct gadget_info, functions_group);

        mutex_lock(&gi->lock);
        list_del(&fi->cfs_list);
        mutex_unlock(&gi->lock);
        config_item_put(item);
}

static const struct configfs_group_operations functions_ops = {
        .make_group     = &function_make,
        .drop_item      = &function_drop,
};

static const struct config_item_type functions_type = {
        .ct_group_ops   = &functions_ops,
        .ct_owner       = THIS_MODULE,
};

GS_STRINGS_RW(gadget_config_name, configuration);

static struct configfs_attribute *gadget_config_name_langid_attrs[] = {
        &gadget_config_name_attr_configuration,
        NULL,
};

static void gadget_config_name_attr_release(struct config_item *item)
{
        struct gadget_config_name *cn = to_gadget_config_name(item);

        kfree(cn->configuration);

        list_del(&cn->list);
        kfree(cn);
}

USB_CONFIG_STRING_RW_OPS(gadget_config_name);
USB_CONFIG_STRINGS_LANG(gadget_config_name, config_usb_cfg);

static struct config_group *config_desc_make(
                struct config_group *group,
                const char *name)
{
        struct gadget_info *gi;
        struct config_usb_cfg *cfg;
        char buf[MAX_NAME_LEN];
        char *num_str;
        u8 num;
        int ret;

        gi = container_of(group, struct gadget_info, configs_group);

        if (strlen(name) >= MAX_NAME_LEN)
                return ERR_PTR(-ENAMETOOLONG);

        scnprintf(buf, MAX_NAME_LEN, "%s", name);

        num_str = strchr(buf, '.');
        if (!num_str) {
                pr_err("Unable to locate . in name.bConfigurationValue\n");
                return ERR_PTR(-EINVAL);
        }

        *num_str = '\0';
        num_str++;

        if (!strlen(buf))
                return ERR_PTR(-EINVAL);

        ret = kstrtou8(num_str, 0, &num);
        if (ret)
                return ERR_PTR(ret);

        cfg = kzalloc_obj(*cfg);
        if (!cfg)
                return ERR_PTR(-ENOMEM);
        cfg->c.label = kstrdup(buf, GFP_KERNEL);
        if (!cfg->c.label) {
                ret = -ENOMEM;
                goto err;
        }
        cfg->c.bConfigurationValue = num;
        cfg->c.MaxPower = CONFIG_USB_GADGET_VBUS_DRAW;
        cfg->c.bmAttributes = USB_CONFIG_ATT_ONE;
        INIT_LIST_HEAD(&cfg->string_list);
        INIT_LIST_HEAD(&cfg->func_list);

        config_group_init_type_name(&cfg->group, name,
                                &gadget_config_type);

        config_group_init_type_name(&cfg->strings_group, "strings",
                        &gadget_config_name_strings_type);
        configfs_add_default_group(&cfg->strings_group, &cfg->group);

        ret = usb_add_config_only(&gi->cdev, &cfg->c);
        if (ret)
                goto err;

        return &cfg->group;
err:
        kfree(cfg->c.label);
        kfree(cfg);
        return ERR_PTR(ret);
}

static void config_desc_drop(
                struct config_group *group,
                struct config_item *item)
{
        config_item_put(item);
}

static const struct configfs_group_operations config_desc_ops = {
        .make_group     = &config_desc_make,
        .drop_item      = &config_desc_drop,
};

static const struct config_item_type config_desc_type = {
        .ct_group_ops   = &config_desc_ops,
        .ct_owner       = THIS_MODULE,
};

GS_STRINGS_RW(gadget_language, manufacturer);
GS_STRINGS_RW(gadget_language, product);
GS_STRINGS_RW(gadget_language, serialnumber);

static struct configfs_attribute *gadget_language_langid_attrs[] = {
        &gadget_language_attr_manufacturer,
        &gadget_language_attr_product,
        &gadget_language_attr_serialnumber,
        NULL,
};

static void gadget_language_attr_release(struct config_item *item)
{
        struct gadget_language *gs = to_gadget_language(item);

        kfree(gs->manufacturer);
        kfree(gs->product);
        kfree(gs->serialnumber);

        list_del(&gs->list);
        kfree(gs);
}

static const struct configfs_item_operations gadget_language_langid_item_ops = {
        .release                = gadget_language_attr_release,
};

static ssize_t gadget_string_id_show(struct config_item *item, char *page)
{
        struct gadget_string *string = to_gadget_string(item);
        int ret;

        ret = sprintf(page, "%u\n", string->usb_string.id);
        return ret;
}
CONFIGFS_ATTR_RO(gadget_string_, id);

static ssize_t gadget_string_s_show(struct config_item *item, char *page)
{
        struct gadget_string *string = to_gadget_string(item);
        int ret;

        ret = sysfs_emit(page, "%s\n", string->string);
        return ret;
}

static ssize_t gadget_string_s_store(struct config_item *item, const char *page,
                                     size_t len)
{
        struct gadget_string *string = to_gadget_string(item);
        int size = min(sizeof(string->string), len + 1);
        ssize_t cpy_len;

        if (len > USB_MAX_STRING_LEN)
                return -EINVAL;

        cpy_len = strscpy(string->string, page, size);
        if (cpy_len > 0 && string->string[cpy_len - 1] == '\n')
                string->string[cpy_len - 1] = 0;
        return len;
}
CONFIGFS_ATTR(gadget_string_, s);

static struct configfs_attribute *gadget_string_attrs[] = {
        &gadget_string_attr_id,
        &gadget_string_attr_s,
        NULL,
};

static void gadget_string_release(struct config_item *item)
{
        struct gadget_string *string = to_gadget_string(item);

        kfree(string);
}

static const struct configfs_item_operations gadget_string_item_ops = {
        .release        = gadget_string_release,
};

static const struct config_item_type gadget_string_type = {
        .ct_item_ops    = &gadget_string_item_ops,
        .ct_attrs       = gadget_string_attrs,
        .ct_owner       = THIS_MODULE,
};

static struct config_item *gadget_language_string_make(struct config_group *group,
                                                       const char *name)
{
        struct gadget_language *language;
        struct gadget_string *string;

        language = to_gadget_language(&group->cg_item);

        string = kzalloc_obj(*string);
        if (!string)
                return ERR_PTR(-ENOMEM);

        string->usb_string.id = language->nstrings++;
        string->usb_string.s = string->string;
        list_add_tail(&string->list, &language->gadget_strings);

        config_item_init_type_name(&string->item, name, &gadget_string_type);

        return &string->item;
}

static void gadget_language_string_drop(struct config_group *group,
                                        struct config_item *item)
{
        struct gadget_language *language;
        struct gadget_string *string;
        unsigned int i = USB_GADGET_FIRST_AVAIL_IDX;

        language = to_gadget_language(&group->cg_item);
        string = to_gadget_string(item);

        list_del(&string->list);
        language->nstrings--;

        /* Reset the ids for the language's strings to guarantee a continuous set */
        list_for_each_entry(string, &language->gadget_strings, list)
                string->usb_string.id = i++;
}

static const struct configfs_group_operations gadget_language_langid_group_ops = {
        .make_item              = gadget_language_string_make,
        .drop_item              = gadget_language_string_drop,
};

static const struct config_item_type gadget_language_type = {
        .ct_item_ops    = &gadget_language_langid_item_ops,
        .ct_group_ops   = &gadget_language_langid_group_ops,
        .ct_attrs       = gadget_language_langid_attrs,
        .ct_owner       = THIS_MODULE,
};

static struct config_group *gadget_language_make(struct config_group *group,
                                                 const char *name)
{
        struct gadget_info *gi;
        struct gadget_language *gs;
        struct gadget_language *new;
        int langs = 0;
        int ret;

        new = kzalloc_obj(*new);
        if (!new)
                return ERR_PTR(-ENOMEM);

        ret = check_user_usb_string(name, &new->stringtab_dev);
        if (ret)
                goto err;
        config_group_init_type_name(&new->group, name,
                                    &gadget_language_type);

        gi = container_of(group, struct gadget_info, strings_group);
        ret = -EEXIST;
        list_for_each_entry(gs, &gi->string_list, list) {
                if (gs->stringtab_dev.language == new->stringtab_dev.language)
                        goto err;
                langs++;
        }
        ret = -EOVERFLOW;
        if (langs >= MAX_USB_STRING_LANGS)
                goto err;

        list_add_tail(&new->list, &gi->string_list);
        INIT_LIST_HEAD(&new->gadget_strings);

        /* We have the default manufacturer, product and serialnumber strings */
        new->nstrings = 3;
        return &new->group;
err:
        kfree(new);
        return ERR_PTR(ret);
}

static void gadget_language_drop(struct config_group *group,
                                 struct config_item *item)
{
        config_item_put(item);
}

static const struct configfs_group_operations gadget_language_group_ops = {
        .make_group     = &gadget_language_make,
        .drop_item      = &gadget_language_drop,
};

static const struct config_item_type gadget_language_strings_type = {
        .ct_group_ops   = &gadget_language_group_ops,
        .ct_owner       = THIS_MODULE,
};

static inline struct gadget_info *webusb_item_to_gadget_info(
                struct config_item *item)
{
        return container_of(to_config_group(item),
                        struct gadget_info, webusb_group);
}

static ssize_t webusb_use_show(struct config_item *item, char *page)
{
        return sysfs_emit(page, "%d\n",
                        webusb_item_to_gadget_info(item)->use_webusb);
}

static ssize_t webusb_use_store(struct config_item *item, const char *page,
                                 size_t len)
{
        struct gadget_info *gi = webusb_item_to_gadget_info(item);
        int ret;
        bool use;

        ret = kstrtobool(page, &use);
        if (ret)
                return ret;

        mutex_lock(&gi->lock);
        gi->use_webusb = use;
        mutex_unlock(&gi->lock);

        return len;
}

static ssize_t webusb_bcdVersion_show(struct config_item *item, char *page)
{
        return sysfs_emit(page, "0x%04x\n",
                                        webusb_item_to_gadget_info(item)->bcd_webusb_version);
}

static ssize_t webusb_bcdVersion_store(struct config_item *item,
                const char *page, size_t len)
{
        struct gadget_info *gi = webusb_item_to_gadget_info(item);
        u16 bcdVersion;
        int ret;

        ret = kstrtou16(page, 0, &bcdVersion);
        if (ret)
                return ret;

        ret = is_valid_bcd(bcdVersion);
        if (ret)
                return ret;

        mutex_lock(&gi->lock);
        gi->bcd_webusb_version = bcdVersion;
        mutex_unlock(&gi->lock);

        return len;
}

static ssize_t webusb_bVendorCode_show(struct config_item *item, char *page)
{
        return sysfs_emit(page, "0x%02x\n",
                        webusb_item_to_gadget_info(item)->b_webusb_vendor_code);
}

static ssize_t webusb_bVendorCode_store(struct config_item *item,
                                           const char *page, size_t len)
{
        struct gadget_info *gi = webusb_item_to_gadget_info(item);
        int ret;
        u8 b_vendor_code;

        ret = kstrtou8(page, 0, &b_vendor_code);
        if (ret)
                return ret;

        mutex_lock(&gi->lock);
        gi->b_webusb_vendor_code = b_vendor_code;
        mutex_unlock(&gi->lock);

        return len;
}

static ssize_t webusb_landingPage_show(struct config_item *item, char *page)
{
        return sysfs_emit(page, "%s\n", webusb_item_to_gadget_info(item)->landing_page);
}

static ssize_t webusb_landingPage_store(struct config_item *item, const char *page,
                                     size_t len)
{
        struct gadget_info *gi = webusb_item_to_gadget_info(item);
        unsigned int bytes_to_strip = 0;
        int l = len;

        if (!len)
                return len;
        if (page[l - 1] == '\n') {
                --l;
                ++bytes_to_strip;
        }

        if (l > sizeof(gi->landing_page)) {
                pr_err("webusb: landingPage URL too long\n");
                return -EINVAL;
        }

        // validation
        if (strncasecmp(page, "https://",  8) == 0)
                bytes_to_strip = 8;
        else if (strncasecmp(page, "http://", 7) == 0)
                bytes_to_strip = 7;
        else
                bytes_to_strip = 0;

        if (l > U8_MAX - WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH + bytes_to_strip) {
                pr_err("webusb: landingPage URL %d bytes too long for given URL scheme\n",
                        l - U8_MAX + WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH - bytes_to_strip);
                return -EINVAL;
        }

        mutex_lock(&gi->lock);
        // ensure 0 bytes are set, in case the new landing page is shorter then the old one.
        memcpy_and_pad(gi->landing_page, sizeof(gi->landing_page), page, l, 0);
        mutex_unlock(&gi->lock);

        return len;
}

CONFIGFS_ATTR(webusb_, use);
CONFIGFS_ATTR(webusb_, bVendorCode);
CONFIGFS_ATTR(webusb_, bcdVersion);
CONFIGFS_ATTR(webusb_, landingPage);

static struct configfs_attribute *webusb_attrs[] = {
        &webusb_attr_use,
        &webusb_attr_bcdVersion,
        &webusb_attr_bVendorCode,
        &webusb_attr_landingPage,
        NULL,
};

static const struct config_item_type webusb_type = {
        .ct_attrs       = webusb_attrs,
        .ct_owner       = THIS_MODULE,
};

static inline struct gadget_info *os_desc_item_to_gadget_info(
                struct config_item *item)
{
        return container_of(to_config_group(item),
                        struct gadget_info, os_desc_group);
}

static ssize_t os_desc_use_show(struct config_item *item, char *page)
{
        return sprintf(page, "%d\n",
                        os_desc_item_to_gadget_info(item)->use_os_desc);
}

static ssize_t os_desc_use_store(struct config_item *item, const char *page,
                                 size_t len)
{
        struct gadget_info *gi = os_desc_item_to_gadget_info(item);
        int ret;
        bool use;

        ret = kstrtobool(page, &use);
        if (ret)
                return ret;

        mutex_lock(&gi->lock);
        gi->use_os_desc = use;
        mutex_unlock(&gi->lock);

        return len;
}

static ssize_t os_desc_b_vendor_code_show(struct config_item *item, char *page)
{
        return sprintf(page, "0x%02x\n",
                        os_desc_item_to_gadget_info(item)->b_vendor_code);
}

static ssize_t os_desc_b_vendor_code_store(struct config_item *item,
                                           const char *page, size_t len)
{
        struct gadget_info *gi = os_desc_item_to_gadget_info(item);
        int ret;
        u8 b_vendor_code;

        ret = kstrtou8(page, 0, &b_vendor_code);
        if (ret)
                return ret;

        mutex_lock(&gi->lock);
        gi->b_vendor_code = b_vendor_code;
        mutex_unlock(&gi->lock);

        return len;
}

static ssize_t os_desc_qw_sign_show(struct config_item *item, char *page)
{
        struct gadget_info *gi = os_desc_item_to_gadget_info(item);
        int res;

        res = utf16s_to_utf8s((wchar_t *) gi->qw_sign, OS_STRING_QW_SIGN_LEN,
                              UTF16_LITTLE_ENDIAN, page, PAGE_SIZE - 1);
        page[res++] = '\n';

        return res;
}

static ssize_t os_desc_qw_sign_store(struct config_item *item, const char *page,
                                     size_t len)
{
        struct gadget_info *gi = os_desc_item_to_gadget_info(item);
        int res, l;

        if (!len)
                return len;
        l = min_t(int, len, OS_STRING_QW_SIGN_LEN >> 1);
        if (page[l - 1] == '\n')
                --l;

        mutex_lock(&gi->lock);
        res = utf8s_to_utf16s(page, l,
                              UTF16_LITTLE_ENDIAN, (wchar_t *) gi->qw_sign,
                              OS_STRING_QW_SIGN_LEN);
        if (res > 0)
                res = len;
        mutex_unlock(&gi->lock);

        return res;
}

CONFIGFS_ATTR(os_desc_, use);
CONFIGFS_ATTR(os_desc_, b_vendor_code);
CONFIGFS_ATTR(os_desc_, qw_sign);

static struct configfs_attribute *os_desc_attrs[] = {
        &os_desc_attr_use,
        &os_desc_attr_b_vendor_code,
        &os_desc_attr_qw_sign,
        NULL,
};

static int os_desc_link(struct config_item *os_desc_ci,
                        struct config_item *usb_cfg_ci)
{
        struct gadget_info *gi = os_desc_item_to_gadget_info(os_desc_ci);
        struct usb_composite_dev *cdev = &gi->cdev;
        struct config_usb_cfg *c_target = to_config_usb_cfg(usb_cfg_ci);
        struct usb_configuration *c = NULL, *iter;
        int ret;

        mutex_lock(&gi->lock);
        list_for_each_entry(iter, &cdev->configs, list) {
                if (iter != &c_target->c)
                        continue;
                c = iter;
                break;
        }
        if (!c) {
                ret = -EINVAL;
                goto out;
        }

        if (cdev->os_desc_config) {
                ret = -EBUSY;
                goto out;
        }

        cdev->os_desc_config = &c_target->c;
        ret = 0;

out:
        mutex_unlock(&gi->lock);
        return ret;
}

static void os_desc_unlink(struct config_item *os_desc_ci,
                          struct config_item *usb_cfg_ci)
{
        struct gadget_info *gi = os_desc_item_to_gadget_info(os_desc_ci);
        struct usb_composite_dev *cdev = &gi->cdev;

        mutex_lock(&gi->lock);
        if (gi->composite.gadget_driver.udc_name)
                unregister_gadget(gi);
        cdev->os_desc_config = NULL;
        WARN_ON(gi->composite.gadget_driver.udc_name);
        mutex_unlock(&gi->lock);
}

static const struct configfs_item_operations os_desc_ops = {
        .allow_link             = os_desc_link,
        .drop_link              = os_desc_unlink,
};

static const struct config_item_type os_desc_type = {
        .ct_item_ops    = &os_desc_ops,
        .ct_attrs       = os_desc_attrs,
        .ct_owner       = THIS_MODULE,
};

static inline struct usb_os_desc_ext_prop
*to_usb_os_desc_ext_prop(struct config_item *item)
{
        return container_of(item, struct usb_os_desc_ext_prop, item);
}

static ssize_t ext_prop_type_show(struct config_item *item, char *page)
{
        return sprintf(page, "%d\n", to_usb_os_desc_ext_prop(item)->type);
}

static ssize_t ext_prop_type_store(struct config_item *item,
                                   const char *page, size_t len)
{
        struct usb_os_desc_ext_prop *ext_prop = to_usb_os_desc_ext_prop(item);
        struct usb_os_desc *desc = to_usb_os_desc(ext_prop->item.ci_parent);
        u8 type;
        int ret;

        ret = kstrtou8(page, 0, &type);
        if (ret)
                return ret;

        if (type < USB_EXT_PROP_UNICODE || type > USB_EXT_PROP_UNICODE_MULTI)
                return -EINVAL;

        if (desc->opts_mutex)
                mutex_lock(desc->opts_mutex);

        if ((ext_prop->type == USB_EXT_PROP_BINARY ||
            ext_prop->type == USB_EXT_PROP_LE32 ||
            ext_prop->type == USB_EXT_PROP_BE32) &&
            (type == USB_EXT_PROP_UNICODE ||
            type == USB_EXT_PROP_UNICODE_ENV ||
            type == USB_EXT_PROP_UNICODE_LINK))
                ext_prop->data_len <<= 1;
        else if ((ext_prop->type == USB_EXT_PROP_UNICODE ||
                   ext_prop->type == USB_EXT_PROP_UNICODE_ENV ||
                   ext_prop->type == USB_EXT_PROP_UNICODE_LINK) &&
                   (type == USB_EXT_PROP_BINARY ||
                   type == USB_EXT_PROP_LE32 ||
                   type == USB_EXT_PROP_BE32))
                ext_prop->data_len >>= 1;
        ext_prop->type = type;

        if (desc->opts_mutex)
                mutex_unlock(desc->opts_mutex);
        return len;
}

static ssize_t ext_prop_data_show(struct config_item *item, char *page)
{
        struct usb_os_desc_ext_prop *ext_prop = to_usb_os_desc_ext_prop(item);
        int len = ext_prop->data_len;

        if (ext_prop->type == USB_EXT_PROP_UNICODE ||
            ext_prop->type == USB_EXT_PROP_UNICODE_ENV ||
            ext_prop->type == USB_EXT_PROP_UNICODE_LINK)
                len >>= 1;
        memcpy(page, ext_prop->data, len);

        return len;
}

static ssize_t ext_prop_data_store(struct config_item *item,
                                   const char *page, size_t len)
{
        struct usb_os_desc_ext_prop *ext_prop = to_usb_os_desc_ext_prop(item);
        struct usb_os_desc *desc = to_usb_os_desc(ext_prop->item.ci_parent);
        char *new_data;
        size_t ret_len = len;

        if (page[len - 1] == '\n' || page[len - 1] == '\0')
                --len;
        new_data = kmemdup(page, len, GFP_KERNEL);
        if (!new_data)
                return -ENOMEM;

        if (desc->opts_mutex)
                mutex_lock(desc->opts_mutex);
        kfree(ext_prop->data);
        ext_prop->data = new_data;
        desc->ext_prop_len -= ext_prop->data_len;
        ext_prop->data_len = len;
        desc->ext_prop_len += ext_prop->data_len;
        if (ext_prop->type == USB_EXT_PROP_UNICODE ||
            ext_prop->type == USB_EXT_PROP_UNICODE_ENV ||
            ext_prop->type == USB_EXT_PROP_UNICODE_LINK) {
                desc->ext_prop_len -= ext_prop->data_len;
                ext_prop->data_len <<= 1;
                ext_prop->data_len += 2;
                desc->ext_prop_len += ext_prop->data_len;
        }
        if (desc->opts_mutex)
                mutex_unlock(desc->opts_mutex);
        return ret_len;
}

CONFIGFS_ATTR(ext_prop_, type);
CONFIGFS_ATTR(ext_prop_, data);

static struct configfs_attribute *ext_prop_attrs[] = {
        &ext_prop_attr_type,
        &ext_prop_attr_data,
        NULL,
};

static void usb_os_desc_ext_prop_release(struct config_item *item)
{
        struct usb_os_desc_ext_prop *ext_prop = to_usb_os_desc_ext_prop(item);

        kfree(ext_prop); /* frees a whole chunk */
}

static const struct configfs_item_operations ext_prop_ops = {
        .release                = usb_os_desc_ext_prop_release,
};

static struct config_item *ext_prop_make(
                struct config_group *group,
                const char *name)
{
        struct usb_os_desc_ext_prop *ext_prop;
        struct config_item_type *ext_prop_type;
        struct usb_os_desc *desc;
        char *vlabuf;

        vla_group(data_chunk);
        vla_item(data_chunk, struct usb_os_desc_ext_prop, ext_prop, 1);
        vla_item(data_chunk, struct config_item_type, ext_prop_type, 1);

        vlabuf = kzalloc(vla_group_size(data_chunk), GFP_KERNEL);
        if (!vlabuf)
                return ERR_PTR(-ENOMEM);

        ext_prop = vla_ptr(vlabuf, data_chunk, ext_prop);
        ext_prop_type = vla_ptr(vlabuf, data_chunk, ext_prop_type);

        desc = container_of(group, struct usb_os_desc, group);
        ext_prop_type->ct_item_ops = &ext_prop_ops;
        ext_prop_type->ct_attrs = ext_prop_attrs;
        ext_prop_type->ct_owner = desc->owner;

        config_item_init_type_name(&ext_prop->item, name, ext_prop_type);

        ext_prop->name = kstrdup(name, GFP_KERNEL);
        if (!ext_prop->name) {
                kfree(vlabuf);
                return ERR_PTR(-ENOMEM);
        }
        desc->ext_prop_len += 14;
        ext_prop->name_len = 2 * strlen(ext_prop->name) + 2;
        if (desc->opts_mutex)
                mutex_lock(desc->opts_mutex);
        desc->ext_prop_len += ext_prop->name_len;
        list_add_tail(&ext_prop->entry, &desc->ext_prop);
        ++desc->ext_prop_count;
        if (desc->opts_mutex)
                mutex_unlock(desc->opts_mutex);

        return &ext_prop->item;
}

static void ext_prop_drop(struct config_group *group, struct config_item *item)
{
        struct usb_os_desc_ext_prop *ext_prop = to_usb_os_desc_ext_prop(item);
        struct usb_os_desc *desc = to_usb_os_desc(&group->cg_item);

        if (desc->opts_mutex)
                mutex_lock(desc->opts_mutex);
        list_del(&ext_prop->entry);
        --desc->ext_prop_count;
        kfree(ext_prop->name);
        desc->ext_prop_len -= (ext_prop->name_len + ext_prop->data_len + 14);
        if (desc->opts_mutex)
                mutex_unlock(desc->opts_mutex);
        config_item_put(item);
}

static const struct configfs_group_operations interf_grp_ops = {
        .make_item      = &ext_prop_make,
        .drop_item      = &ext_prop_drop,
};

static ssize_t interf_grp_compatible_id_show(struct config_item *item,
                                             char *page)
{
        memcpy(page, to_usb_os_desc(item)->ext_compat_id, 8);
        return 8;
}

static ssize_t interf_grp_compatible_id_store(struct config_item *item,
                                              const char *page, size_t len)
{
        struct usb_os_desc *desc = to_usb_os_desc(item);
        int l;

        l = min_t(int, 8, len);
        if (page[l - 1] == '\n')
                --l;
        if (desc->opts_mutex)
                mutex_lock(desc->opts_mutex);
        memcpy(desc->ext_compat_id, page, l);

        if (desc->opts_mutex)
                mutex_unlock(desc->opts_mutex);

        return len;
}

static ssize_t interf_grp_sub_compatible_id_show(struct config_item *item,
                                                 char *page)
{
        memcpy(page, to_usb_os_desc(item)->ext_compat_id + 8, 8);
        return 8;
}

static ssize_t interf_grp_sub_compatible_id_store(struct config_item *item,
                                                  const char *page, size_t len)
{
        struct usb_os_desc *desc = to_usb_os_desc(item);
        int l;

        l = min_t(int, 8, len);
        if (page[l - 1] == '\n')
                --l;
        if (desc->opts_mutex)
                mutex_lock(desc->opts_mutex);
        memcpy(desc->ext_compat_id + 8, page, l);

        if (desc->opts_mutex)
                mutex_unlock(desc->opts_mutex);

        return len;
}

CONFIGFS_ATTR(interf_grp_, compatible_id);
CONFIGFS_ATTR(interf_grp_, sub_compatible_id);

static struct configfs_attribute *interf_grp_attrs[] = {
        &interf_grp_attr_compatible_id,
        &interf_grp_attr_sub_compatible_id,
        NULL
};

struct config_group *usb_os_desc_prepare_interf_dir(
                struct config_group *parent,
                int n_interf,
                struct usb_os_desc **desc,
                char **names,
                struct module *owner)
{
        struct config_group *os_desc_group;
        struct config_item_type *os_desc_type, *interface_type;

        vla_group(data_chunk);
        vla_item(data_chunk, struct config_group, os_desc_group, 1);
        vla_item(data_chunk, struct config_item_type, os_desc_type, 1);
        vla_item(data_chunk, struct config_item_type, interface_type, 1);

        char *vlabuf = kzalloc(vla_group_size(data_chunk), GFP_KERNEL);
        if (!vlabuf)
                return ERR_PTR(-ENOMEM);

        os_desc_group = vla_ptr(vlabuf, data_chunk, os_desc_group);
        os_desc_type = vla_ptr(vlabuf, data_chunk, os_desc_type);
        interface_type = vla_ptr(vlabuf, data_chunk, interface_type);

        os_desc_type->ct_owner = owner;
        config_group_init_type_name(os_desc_group, "os_desc", os_desc_type);
        configfs_add_default_group(os_desc_group, parent);

        interface_type->ct_group_ops = &interf_grp_ops;
        interface_type->ct_attrs = interf_grp_attrs;
        interface_type->ct_owner = owner;

        while (n_interf--) {
                struct usb_os_desc *d;

                d = desc[n_interf];
                d->owner = owner;
                config_group_init_type_name(&d->group, "", interface_type);
                config_item_set_name(&d->group.cg_item, "interface.%s",
                                     names[n_interf]);
                configfs_add_default_group(&d->group, os_desc_group);
        }

        return os_desc_group;
}
EXPORT_SYMBOL(usb_os_desc_prepare_interf_dir);

static int configfs_do_nothing(struct usb_composite_dev *cdev)
{
        WARN_ON(1);
        return -EINVAL;
}

int composite_dev_prepare(struct usb_composite_driver *composite,
                struct usb_composite_dev *dev);

int composite_os_desc_req_prepare(struct usb_composite_dev *cdev,
                                  struct usb_ep *ep0);

static void purge_configs_funcs(struct gadget_info *gi)
{
        struct usb_configuration        *c;

        list_for_each_entry(c, &gi->cdev.configs, list) {
                struct usb_function *f, *tmp;
                struct config_usb_cfg *cfg;

                cfg = container_of(c, struct config_usb_cfg, c);

                list_for_each_entry_safe_reverse(f, tmp, &c->functions, list) {

                        list_move(&f->list, &cfg->func_list);
                        if (f->unbind) {
                                dev_dbg(&gi->cdev.gadget->dev,
                                        "unbind function '%s'/%p\n",
                                        f->name, f);
                                f->unbind(c, f);
                        }
                }
                c->next_interface_id = 0;
                memset(c->interface, 0, sizeof(c->interface));
                c->superspeed_plus = 0;
                c->superspeed = 0;
                c->highspeed = 0;
                c->fullspeed = 0;
        }
}

static struct usb_string *
configfs_attach_gadget_strings(struct gadget_info *gi)
{
        struct usb_gadget_strings **gadget_strings;
        struct gadget_language *language;
        struct gadget_string *string;
        unsigned int nlangs = 0;
        struct list_head *iter;
        struct usb_string *us;
        unsigned int i = 0;
        int nstrings = -1;
        unsigned int j;

        list_for_each(iter, &gi->string_list)
                nlangs++;

        /* Bail out early if no languages are configured */
        if (!nlangs)
                return NULL;

        gadget_strings = kzalloc_objs(struct usb_gadget_strings *, nlangs + 1)/* including NULL terminator */;
        if (!gadget_strings)
                return ERR_PTR(-ENOMEM);

        list_for_each_entry(language, &gi->string_list, list) {
                struct usb_string *stringtab;

                if (nstrings == -1) {
                        nstrings = language->nstrings;
                } else if (nstrings != language->nstrings) {
                        pr_err("languages must contain the same number of strings\n");
                        us = ERR_PTR(-EINVAL);
                        goto cleanup;
                }

                stringtab = kzalloc_objs(struct usb_string,
                                         language->nstrings + 1);
                if (!stringtab) {
                        us = ERR_PTR(-ENOMEM);
                        goto cleanup;
                }

                stringtab[USB_GADGET_MANUFACTURER_IDX].id = USB_GADGET_MANUFACTURER_IDX;
                stringtab[USB_GADGET_MANUFACTURER_IDX].s = language->manufacturer;
                stringtab[USB_GADGET_PRODUCT_IDX].id = USB_GADGET_PRODUCT_IDX;
                stringtab[USB_GADGET_PRODUCT_IDX].s = language->product;
                stringtab[USB_GADGET_SERIAL_IDX].id = USB_GADGET_SERIAL_IDX;
                stringtab[USB_GADGET_SERIAL_IDX].s = language->serialnumber;

                j = USB_GADGET_FIRST_AVAIL_IDX;
                list_for_each_entry(string, &language->gadget_strings, list) {
                        memcpy(&stringtab[j], &string->usb_string, sizeof(struct usb_string));
                        j++;
                }

                language->stringtab_dev.strings = stringtab;
                gadget_strings[i] = &language->stringtab_dev;
                i++;
        }

        us = usb_gstrings_attach(&gi->cdev, gadget_strings, nstrings);

cleanup:
        list_for_each_entry(language, &gi->string_list, list) {
                kfree(language->stringtab_dev.strings);
                language->stringtab_dev.strings = NULL;
        }

        kfree(gadget_strings);

        return us;
}

static int configfs_composite_bind(struct usb_gadget *gadget,
                struct usb_gadget_driver *gdriver)
{
        struct usb_composite_driver     *composite = to_cdriver(gdriver);
        struct gadget_info              *gi = container_of(composite,
                                                struct gadget_info, composite);
        struct usb_composite_dev        *cdev = &gi->cdev;
        struct usb_configuration        *c;
        struct usb_string               *s;
        unsigned                        i;
        int                             ret;

        /* the gi->lock is hold by the caller */
        gi->unbind = 0;
        cdev->gadget = gadget;
        set_gadget_data(gadget, cdev);
        ret = composite_dev_prepare(composite, cdev);
        if (ret)
                return ret;
        /* and now the gadget bind */
        ret = -EINVAL;

        if (list_empty(&gi->cdev.configs)) {
                pr_err("Need at least one configuration in %s.\n",
                                gi->composite.name);
                goto err_comp_cleanup;
        }


        list_for_each_entry(c, &gi->cdev.configs, list) {
                struct config_usb_cfg *cfg;

                cfg = container_of(c, struct config_usb_cfg, c);
                if (list_empty(&cfg->func_list)) {
                        pr_err("Config %s/%d of %s needs at least one function.\n",
                              c->label, c->bConfigurationValue,
                              gi->composite.name);
                        goto err_comp_cleanup;
                }
        }

        /* init all strings */
        if (!list_empty(&gi->string_list)) {
                s = configfs_attach_gadget_strings(gi);
                if (IS_ERR(s)) {
                        ret = PTR_ERR(s);
                        goto err_comp_cleanup;
                }

                gi->cdev.desc.iManufacturer = s[USB_GADGET_MANUFACTURER_IDX].id;
                gi->cdev.desc.iProduct = s[USB_GADGET_PRODUCT_IDX].id;
                gi->cdev.desc.iSerialNumber = s[USB_GADGET_SERIAL_IDX].id;

                gi->cdev.usb_strings = s;
        }

        if (gi->use_webusb) {
                cdev->use_webusb = true;
                cdev->bcd_webusb_version = gi->bcd_webusb_version;
                cdev->b_webusb_vendor_code = gi->b_webusb_vendor_code;
                memcpy(cdev->landing_page, gi->landing_page, WEBUSB_URL_RAW_MAX_LENGTH);
        }

        if (gi->use_os_desc) {
                cdev->use_os_string = true;
                cdev->b_vendor_code = gi->b_vendor_code;
                memcpy(cdev->qw_sign, gi->qw_sign, OS_STRING_QW_SIGN_LEN);
        } else {
                cdev->use_os_string = false;
        }

        if (gadget_is_otg(gadget) && !otg_desc[0]) {
                struct usb_descriptor_header *usb_desc;

                usb_desc = usb_otg_descriptor_alloc(gadget);
                if (!usb_desc) {
                        ret = -ENOMEM;
                        goto err_comp_cleanup;
                }
                usb_otg_descriptor_init(gadget, usb_desc);
                otg_desc[0] = usb_desc;
                otg_desc[1] = NULL;
        }

        /* Go through all configs, attach all functions */
        list_for_each_entry(c, &gi->cdev.configs, list) {
                struct config_usb_cfg *cfg;
                struct usb_function *f;
                struct usb_function *tmp;
                struct gadget_config_name *cn;

                if (gadget_is_otg(gadget))
                        c->descriptors = otg_desc;

                /* Properly configure the bmAttributes wakeup bit */
                check_remote_wakeup_config(gadget, c);

                cfg = container_of(c, struct config_usb_cfg, c);
                if (!list_empty(&cfg->string_list)) {
                        i = 0;
                        list_for_each_entry(cn, &cfg->string_list, list) {
                                cfg->gstrings[i] = &cn->stringtab_dev;
                                cn->stringtab_dev.strings = &cn->strings;
                                cn->strings.s = cn->configuration;
                                i++;
                        }
                        cfg->gstrings[i] = NULL;
                        s = usb_gstrings_attach(&gi->cdev, cfg->gstrings, 1);
                        if (IS_ERR(s)) {
                                ret = PTR_ERR(s);
                                goto err_comp_cleanup;
                        }
                        c->iConfiguration = s[0].id;
                }

                list_for_each_entry_safe(f, tmp, &cfg->func_list, list) {
                        list_del(&f->list);
                        ret = usb_add_function(c, f);
                        if (ret) {
                                list_add(&f->list, &cfg->func_list);
                                goto err_purge_funcs;
                        }
                }
                ret = usb_gadget_check_config(cdev->gadget);
                if (ret)
                        goto err_purge_funcs;

                usb_ep_autoconfig_reset(cdev->gadget);
        }
        if (cdev->use_os_string) {
                ret = composite_os_desc_req_prepare(cdev, gadget->ep0);
                if (ret)
                        goto err_purge_funcs;
        }

        usb_ep_autoconfig_reset(cdev->gadget);
        return 0;

err_purge_funcs:
        purge_configs_funcs(gi);
err_comp_cleanup:
        composite_dev_cleanup(cdev);
        return ret;
}

static void configfs_composite_unbind(struct usb_gadget *gadget)
{
        struct usb_composite_dev        *cdev;
        struct gadget_info              *gi;
        unsigned long flags;

        /* the gi->lock is hold by the caller */

        cdev = get_gadget_data(gadget);
        gi = container_of(cdev, struct gadget_info, cdev);
        spin_lock_irqsave(&gi->spinlock, flags);
        gi->unbind = 1;
        spin_unlock_irqrestore(&gi->spinlock, flags);

        kfree(otg_desc[0]);
        otg_desc[0] = NULL;
        purge_configs_funcs(gi);
        composite_dev_cleanup(cdev);
        usb_ep_autoconfig_reset(cdev->gadget);
        spin_lock_irqsave(&gi->spinlock, flags);
        cdev->gadget = NULL;
        cdev->deactivations = 0;
        gadget->deactivated = false;
        set_gadget_data(gadget, NULL);
        spin_unlock_irqrestore(&gi->spinlock, flags);
}

static int configfs_composite_setup(struct usb_gadget *gadget,
                const struct usb_ctrlrequest *ctrl)
{
        struct usb_composite_dev *cdev;
        struct gadget_info *gi;
        unsigned long flags;
        int ret;

        cdev = get_gadget_data(gadget);
        if (!cdev)
                return 0;

        gi = container_of(cdev, struct gadget_info, cdev);
        spin_lock_irqsave(&gi->spinlock, flags);
        cdev = get_gadget_data(gadget);
        if (!cdev || gi->unbind) {
                spin_unlock_irqrestore(&gi->spinlock, flags);
                return 0;
        }

        ret = composite_setup(gadget, ctrl);
        spin_unlock_irqrestore(&gi->spinlock, flags);
        return ret;
}

static void configfs_composite_disconnect(struct usb_gadget *gadget)
{
        struct usb_composite_dev *cdev;
        struct gadget_info *gi;
        unsigned long flags;

        cdev = get_gadget_data(gadget);
        if (!cdev)
                return;

        gi = container_of(cdev, struct gadget_info, cdev);
        spin_lock_irqsave(&gi->spinlock, flags);
        cdev = get_gadget_data(gadget);
        if (!cdev || gi->unbind) {
                spin_unlock_irqrestore(&gi->spinlock, flags);
                return;
        }

        composite_disconnect(gadget);
        spin_unlock_irqrestore(&gi->spinlock, flags);
}

static void configfs_composite_reset(struct usb_gadget *gadget)
{
        struct usb_composite_dev *cdev;
        struct gadget_info *gi;
        unsigned long flags;

        cdev = get_gadget_data(gadget);
        if (!cdev)
                return;

        gi = container_of(cdev, struct gadget_info, cdev);
        spin_lock_irqsave(&gi->spinlock, flags);
        cdev = get_gadget_data(gadget);
        if (!cdev || gi->unbind) {
                spin_unlock_irqrestore(&gi->spinlock, flags);
                return;
        }

        composite_reset(gadget);
        spin_unlock_irqrestore(&gi->spinlock, flags);
}

static void configfs_composite_suspend(struct usb_gadget *gadget)
{
        struct usb_composite_dev *cdev;
        struct gadget_info *gi;
        unsigned long flags;

        cdev = get_gadget_data(gadget);
        if (!cdev)
                return;

        gi = container_of(cdev, struct gadget_info, cdev);
        spin_lock_irqsave(&gi->spinlock, flags);
        cdev = get_gadget_data(gadget);
        if (!cdev || gi->unbind) {
                spin_unlock_irqrestore(&gi->spinlock, flags);
                return;
        }

        composite_suspend(gadget);
        spin_unlock_irqrestore(&gi->spinlock, flags);
}

static void configfs_composite_resume(struct usb_gadget *gadget)
{
        struct usb_composite_dev *cdev;
        struct gadget_info *gi;
        unsigned long flags;

        cdev = get_gadget_data(gadget);
        if (!cdev)
                return;

        gi = container_of(cdev, struct gadget_info, cdev);
        spin_lock_irqsave(&gi->spinlock, flags);
        cdev = get_gadget_data(gadget);
        if (!cdev || gi->unbind) {
                spin_unlock_irqrestore(&gi->spinlock, flags);
                return;
        }

        composite_resume(gadget);
        spin_unlock_irqrestore(&gi->spinlock, flags);
}

static const struct usb_gadget_driver configfs_driver_template = {
        .bind           = configfs_composite_bind,
        .unbind         = configfs_composite_unbind,

        .setup          = configfs_composite_setup,
        .reset          = configfs_composite_reset,
        .disconnect     = configfs_composite_disconnect,

        .suspend        = configfs_composite_suspend,
        .resume         = configfs_composite_resume,

        .max_speed      = USB_SPEED_SUPER_PLUS,
        .driver = {
                .owner          = THIS_MODULE,
        },
        .match_existing_only = 1,
};

static struct config_group *gadgets_make(
                struct config_group *group,
                const char *name)
{
        struct gadget_info *gi;

        gi = kzalloc_obj(*gi);
        if (!gi)
                return ERR_PTR(-ENOMEM);

        config_group_init_type_name(&gi->group, name, &gadget_root_type);

        config_group_init_type_name(&gi->functions_group, "functions",
                        &functions_type);
        configfs_add_default_group(&gi->functions_group, &gi->group);

        config_group_init_type_name(&gi->configs_group, "configs",
                        &config_desc_type);
        configfs_add_default_group(&gi->configs_group, &gi->group);

        config_group_init_type_name(&gi->strings_group, "strings",
                        &gadget_language_strings_type);
        configfs_add_default_group(&gi->strings_group, &gi->group);

        config_group_init_type_name(&gi->os_desc_group, "os_desc",
                        &os_desc_type);
        configfs_add_default_group(&gi->os_desc_group, &gi->group);

        config_group_init_type_name(&gi->webusb_group, "webusb",
                        &webusb_type);
        configfs_add_default_group(&gi->webusb_group, &gi->group);

        gi->composite.bind = configfs_do_nothing;
        gi->composite.unbind = configfs_do_nothing;
        gi->composite.suspend = NULL;
        gi->composite.resume = NULL;
        gi->composite.max_speed = USB_SPEED_SUPER_PLUS;

        spin_lock_init(&gi->spinlock);
        mutex_init(&gi->lock);
        INIT_LIST_HEAD(&gi->string_list);
        INIT_LIST_HEAD(&gi->available_func);

        composite_init_dev(&gi->cdev);
        gi->cdev.desc.bLength = USB_DT_DEVICE_SIZE;
        gi->cdev.desc.bDescriptorType = USB_DT_DEVICE;
        gi->cdev.desc.bcdDevice = cpu_to_le16(get_default_bcdDevice());

        gi->composite.gadget_driver = configfs_driver_template;

        gi->composite.gadget_driver.driver.name = kasprintf(GFP_KERNEL,
                                                            "configfs-gadget.%s", name);
        if (!gi->composite.gadget_driver.driver.name)
                goto err;

        gi->composite.gadget_driver.function = kstrdup(name, GFP_KERNEL);
        gi->composite.name = gi->composite.gadget_driver.function;

        if (!gi->composite.gadget_driver.function)
                goto out_free_driver_name;

        return &gi->group;

out_free_driver_name:
        kfree(gi->composite.gadget_driver.driver.name);
err:
        kfree(gi);
        return ERR_PTR(-ENOMEM);
}

static void gadgets_drop(struct config_group *group, struct config_item *item)
{
        config_item_put(item);
}

static const struct configfs_group_operations gadgets_ops = {
        .make_group     = &gadgets_make,
        .drop_item      = &gadgets_drop,
};

static const struct config_item_type gadgets_type = {
        .ct_group_ops   = &gadgets_ops,
        .ct_owner       = THIS_MODULE,
};

static struct configfs_subsystem gadget_subsys = {
        .su_group = {
                .cg_item = {
                        .ci_namebuf = "usb_gadget",
                        .ci_type = &gadgets_type,
                },
        },
        .su_mutex = __MUTEX_INITIALIZER(gadget_subsys.su_mutex),
};

void unregister_gadget_item(struct config_item *item)
{
        struct gadget_info *gi = to_gadget_info(item);

        mutex_lock(&gi->lock);
        unregister_gadget(gi);
        mutex_unlock(&gi->lock);
}
EXPORT_SYMBOL_GPL(unregister_gadget_item);

static int __init gadget_cfs_init(void)
{
        int ret;

        config_group_init(&gadget_subsys.su_group);

        ret = configfs_register_subsystem(&gadget_subsys);
        return ret;
}
module_init(gadget_cfs_init);

static void __exit gadget_cfs_exit(void)
{
        configfs_unregister_subsystem(&gadget_subsys);
}
module_exit(gadget_cfs_exit);