|# modprobe dummy_hcd num=2

|# find /sys/kernel/config/ -ls

|   557    0 drwxr-xr-x   3 root     root            0 Nov 29 17:26 
/sys/kernel/config/
|   558    0 drwxr-xr-x   5 root     root            0 Nov 29 17:26 
/sys/kernel/config/usb_gadget
|   561    0 drwxr-xr-x   4 root     root            0 Nov 29 17:26 
/sys/kernel/config/usb_gadget/udcs
|   569    0 drwxr-xr-x   2 root     root            0 Nov 29 17:26 
/sys/kernel/config/usb_gadget/udcs/dummy_udc.1
|   568    0 drwxr-xr-x   2 root     root            0 Nov 29 17:26 
/sys/kernel/config/usb_gadget/udcs/dummy_udc.0
|   560    0 drwxr-xr-x   2 root     root            0 Nov 29 17:26 
/sys/kernel/config/usb_gadget/gadgets

| # lsmod
| Module                  Size  Used by
| dummy_hcd              20287  0
| udc                    10219  1 dummy_hcd

|# mkdir /sys/kernel/config/usb_gadget/gadgets/oha
|# cd /sys/kernel/config/usb_gadget/gadgets/oha
|# mkdir configs/def.1
|# mkdir configs/def.2
|# mkdir functions/acm.ttyS1
|# mkdir strings/0x1
| mkdir: cannot create directory `strings/0x1': Invalid argument
|# mkdir strings/0x409
|# mkdir strings/1033
| mkdir: cannot create directory `strings/1033': File exists
|# mkdir strings/1032

|# find . -ls
|  8555    0 drwxr-xr-x   5 root     root            0 Dec 10 19:29 .
|  8558    0 drwxr-xr-x   4 root     root            0 Dec 10 19:30 ./strings
|  8565    0 drwxr-xr-x   2 root     root            0 Dec 10 19:30 
./strings/1032
|  1948    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./strings/1032/serialnumber
|  1949    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./strings/1032/product
|  1950    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./strings/1032/manufacturer
|   949    0 drwxr-xr-x   2 root     root            0 Dec 10 19:30 
./strings/0x409
|  1951    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./strings/0x409/serialnumber
|  1952    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./strings/0x409/product
|  1953    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./strings/0x409/manufacturer
|  8557    0 drwxr-xr-x   4 root     root            0 Dec 10 19:29 ./configs
|  8559    0 drwxr-xr-x   3 root     root            0 Dec 10 19:29 
./configs/def.2
|  8560    0 drwxr-xr-x   2 root     root            0 Dec 10 19:29 
./configs/def.2/strings
|  1954    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./configs/def.2/bmAttributes
|  1955    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./configs/def.2/MaxPower
|  9253    0 drwxr-xr-x   3 root     root            0 Dec 10 19:29 
./configs/def.1
|  9254    0 drwxr-xr-x   2 root     root            0 Dec 10 19:29 
./configs/def.1/strings
|  1956    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./configs/def.1/bmAttributes
|  1957    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./configs/def.1/MaxPower
|  8556    0 drwxr-xr-x   3 root     root            0 Dec 10 19:29 ./functions
|  9256    0 drwxr-xr-x   2 root     root            0 Dec 10 19:29 
./functions/acm.ttyS1
|  1958    0 -r--r--r--   1 root     root         4096 Dec 10 19:31 
./functions/acm.ttyS1/port_num
|  1959    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 ./bcdUSB
|  1960    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 ./idProduct
|  1961    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 ./idVendor
|  1962    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./bMaxPacketSize0
|  1963    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./bDeviceProtocol
|  1964    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./bDeviceSubClass
|  1965    0 -rw-r--r--   1 root     root         4096 Dec 10 19:31 
./bDeviceClass

|# mkdir default.0
|mkdir: cannot create directory `default.0': Invalid argument
|oha# mkdir another.2
|mkdir: cannot create directory `another.1': File exists

v4…v5
- string rework. This will add a strings folder incl. language code like
    strings/409/manufacturer
  as suggested by Alan.
- rebased ontop reworked functions.c which has usb_function_instance
  which is used prior after "mkdir acm.instance" and can be directly
  used for configuration via configfs.
  symlinking not complete but it is getting there.


v3…v4
 - moved functions from the root folde down to the gadget as suggested
   by Michał
 - configs have now their own configs folder as suggested by Michał.
   The folder is still name.bConfigurationValue where name becomes the
   sConfiguration. Is this usefull should we just stilc
   configs/bConfigurationValue/ ?
 - added configfs support to the ACM function. The port_num attribute is
   exported by f_acm. An argument has been added to the USB alloc
   function to distinguish between "old" (use facm_configure() to
   configure and configfs interface (expose a config_node).
   The port_num is currently a dumb counter. It will
   require some function re-work to make it work.

v2…v3
- replaced one ifndef by ifdef as suggested by Micahał
- strstr()/strchr() function_make as suggested by Micahł
- replace [iSerialNumber|iProduct|iManufacturer] with
  [sSerialNumber|sProduct|sManufacturer] as suggested by Alan
- added creation of config descriptors

v1…v2
- moved gadgets from configfs' root directory into /udcs/ within our
  "usb_gadget" folder. Requested by Andrzej & Michał
- use a dot as a delimiter between function's name and its instance's name
  as suggested by Michał
- renamed all config_item_type, configfs_group_operations, make_group,
  drop_item as suggested by suggested by Andrzej to remain consisten
  within this file and within other configfs users
- Since configfs.c and functions.c are now part of the udc-core module,
  the module itself is now called udc. Also added a tiny ifdef around
  init code becuase udc-core is subsys init and this is too early for
  configfs in the built-in case. In the module case, we can only have
  one init function.

Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
---
 drivers/usb/gadget/Makefile         |    5 +-
 drivers/usb/gadget/configfs.c       |  702 +++++++++++++++++++++++++++++++++++
 drivers/usb/gadget/f_acm.c          |   58 +++
 drivers/usb/gadget/udc-core.c       |   24 ++
 include/linux/usb/composite.h       |    3 +-
 include/linux/usb/gadget.h          |    5 +
 include/linux/usb/gadget_configfs.h |  109 ++++++
 7 files changed, 903 insertions(+), 3 deletions(-)
 create mode 100644 drivers/usb/gadget/configfs.c
 create mode 100644 include/linux/usb/gadget_configfs.h

diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
index 97a13c3..8171093 100644
--- a/drivers/usb/gadget/Makefile
+++ b/drivers/usb/gadget/Makefile
@@ -3,10 +3,11 @@
 #
 ccflags-$(CONFIG_USB_GADGET_DEBUG) := -DDEBUG
 
-obj-$(CONFIG_USB_GADGET)       += udc-core.o
+obj-$(CONFIG_USB_GADGET)       += udc.o
+udc-y                          += udc-core.o configfs.o functions.o
 obj-$(CONFIG_USB_LIBCOMPOSITE) += libcomposite.o
 libcomposite-y                 := usbstring.o config.o epautoconf.o
-libcomposite-y                 += composite.o functions.o
+libcomposite-y                 += composite.o
 obj-$(CONFIG_USB_DUMMY_HCD)    += dummy_hcd.o
 obj-$(CONFIG_USB_NET2272)      += net2272.o
 obj-$(CONFIG_USB_NET2280)      += net2280.o
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
new file mode 100644
index 0000000..8f251cb
--- /dev/null
+++ b/drivers/usb/gadget/configfs.c
@@ -0,0 +1,702 @@
+#include <linux/configfs.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/usb/composite.h>
+#include <linux/usb/gadget_configfs.h>
+
+int check_user_usb_string(const char *name,
+               struct usb_gadget_strings *stringtab_dev)
+{
+       unsigned primary_lang;
+       unsigned sub_lang;
+       u16 num;
+       int ret;
+
+       ret = kstrtou16(name, 0, &num);
+       if (ret)
+               return ret;
+
+       primary_lang = num & 0x3ff;
+       sub_lang = num >> 10;
+
+       /* simple sanity check for valid langid */
+       switch (primary_lang) {
+       case 0:
+       case 0x62 ... 0xfe:
+       case 0x100 ... 0x3ff:
+               return -EINVAL;
+       }
+       if (!sub_lang)
+               return -EINVAL;
+
+       stringtab_dev->language = num;
+       return 0;
+}
+
+#define MAX_NAME_LEN   40
+
+static struct config_item_type gadget_core_type = {
+       .ct_owner       = THIS_MODULE,
+};
+
+static struct config_item_type udc_type = {
+       .ct_owner       = THIS_MODULE,
+};
+
+static struct config_group udc_group = {
+       .cg_item = {
+               .ci_namebuf = "udcs",
+               .ci_type = &udc_type,
+       },
+};
+
+#define MAX_USB_STRING_LANGS   2
+
+struct gadget_info {
+       struct config_group group;
+       struct config_group config_group;
+       struct config_group strings_group;
+       struct config_group *default_groups[4];
+
+       struct usb_device_descriptor device_desc;
+       struct usb_gadget_strings *strings[MAX_USB_STRING_LANGS];
+       struct list_head string_list;
+
+       struct usb_composite_driver driver;
+#ifdef CONFIG_USB_OTG
+       struct usb_otg_descriptor otg;
+#endif
+       struct usb_composite_driver composite;
+       struct usb_composite_dev cdev;
+};
+
+struct config_usb_cfg {
+       struct config_group group;
+       struct config_group strings_group;
+       struct config_group *default_groups[2];
+       struct list_head string_list;
+       struct usb_configuration c;
+};
+
+struct gadget_strings {
+       struct usb_gadget_strings stringtab_dev;
+       struct usb_string stringdev[USB_GADGET_FIRST_AVAIL_IDX];
+       char *manufacturer;
+       char *product;
+       char *serialnumber;
+
+       struct config_group group;
+       struct list_head list;
+};
+
+struct gadget_config_name {
+       struct usb_gadget_strings stringtab_dev;
+       struct usb_string stringdev[USB_GADGET_FIRST_AVAIL_IDX];
+       char *configuration;
+
+       struct config_group group;
+       struct list_head list;
+};
+
+static int usb_string_copy(const char *s, char **s_copy)
+{
+       int ret;
+       char *str;
+       char *copy = *s_copy;
+       ret = strlen(s);
+       if (ret > 126)
+               return -EOVERFLOW;
+
+       str = kstrdup(s, GFP_KERNEL);
+       if (!str)
+               return -ENOMEM;
+       if (str[ret - 1] == '\n')
+               str[ret - 1] = '\0';
+       kfree(copy);
+       *s_copy = str;
+       return 0;
+}
+
+CONFIGFS_ATTR_STRUCT(gadget_info);
+CONFIGFS_ATTR_STRUCT(config_usb_cfg);
+
+#define GI_DEVICE_DESC_ITEM_ATTR(name) \
+       static struct gadget_info_attribute gadget_device_desc_##name = \
+               __CONFIGFS_ATTR(name,  S_IRUGO | S_IWUSR,               \
+                               gadget_dev_desc_##name##_show,          \
+                               gadget_dev_desc_##name##_store)
+
+#define GI_DEVICE_DESC_SIMPLE_R_u8(__name)     \
+       static ssize_t gadget_dev_desc_##__name##_show(struct gadget_info *gi, 
char *page)      \
+{      \
+       return sprintf(page, "0x%02x\n", gi->device_desc.__name);       \
+}
+
+#define GI_DEVICE_DESC_SIMPLE_R_u16(__name)    \
+       static ssize_t gadget_dev_desc_##__name##_show(struct gadget_info *gi, 
char *page)      \
+{      \
+       return sprintf(page, "0x%04x\n", 
le16_to_cpup(&gi->device_desc.__name));        \
+}
+
+
+#define GI_DEVICE_DESC_SIMPLE_W_u8(_name)              \
+       static ssize_t gadget_dev_desc_##_name##_store(struct gadget_info *gi, \
+               const char *page, size_t len)           \
+{                                                      \
+       u8 val;                                         \
+       int ret;                                        \
+       ret = kstrtou8(page, 0, &val);                  \
+       if (ret)                                        \
+               return ret;                             \
+       gi->device_desc._name = val;                    \
+       return len;                                     \
+}
+
+#define GI_DEVICE_DESC_SIMPLE_W_u16(_name)     \
+       static ssize_t gadget_dev_desc_##_name##_store(struct gadget_info *gi, \
+               const char *page, size_t len)           \
+{                                                      \
+       u16 val;                                        \
+       int ret;                                        \
+       ret = kstrtou16(page, 0, &val);                 \
+       if (ret)                                        \
+               return ret;                             \
+       gi->device_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_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(bcdUSB);
+
+static ssize_t gadget_dev_desc_bcdUSB_store(struct gadget_info *gi,
+               const char *page, size_t len)
+{
+       u16 bcdUSB;
+       int ret;
+
+       ret = kstrtou16(page, 0, &bcdUSB);
+       if (ret)
+               return ret;
+       if ((bcdUSB & 0xf) > 9)
+               return -EINVAL;
+       if (((bcdUSB >> 4) & 0xf) > 9)
+               return -EINVAL;
+       if (((bcdUSB >> 8) & 0xf) > 9)
+               return -EINVAL;
+       if (((bcdUSB >> 12) & 0xf) > 9)
+               return -EINVAL;
+
+       gi->device_desc.bcdUSB = cpu_to_le16(bcdUSB);
+       return len;
+}
+
+GI_DEVICE_DESC_ITEM_ATTR(bDeviceClass);
+GI_DEVICE_DESC_ITEM_ATTR(bDeviceSubClass);
+GI_DEVICE_DESC_ITEM_ATTR(bDeviceProtocol);
+GI_DEVICE_DESC_ITEM_ATTR(bMaxPacketSize0);
+GI_DEVICE_DESC_ITEM_ATTR(idVendor);
+GI_DEVICE_DESC_ITEM_ATTR(idProduct);
+GI_DEVICE_DESC_ITEM_ATTR(bcdUSB);
+
+static struct configfs_attribute *gadget_root_attrs[] = {
+       &gadget_device_desc_bDeviceClass.attr,
+       &gadget_device_desc_bDeviceSubClass.attr,
+       &gadget_device_desc_bDeviceProtocol.attr,
+       &gadget_device_desc_bMaxPacketSize0.attr,
+       &gadget_device_desc_idVendor.attr,
+       &gadget_device_desc_idProduct.attr,
+       &gadget_device_desc_bcdUSB.attr,
+       NULL,
+};
+
+static inline struct gadget_info *to_gadget_info(struct config_item *item)
+{
+        return container_of(to_config_group(item), struct gadget_info, group);
+}
+
+static inline struct gadget_strings *to_gadget_strings(struct config_item 
*item)
+{
+        return container_of(to_config_group(item), struct gadget_strings, 
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 config_usb_cfg *to_config_usb_cfg(struct config_item 
*item)
+{
+       return container_of(to_config_group(item), struct config_usb_cfg,
+                       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));
+
+       kfree(gi);
+}
+
+CONFIGFS_ATTR_OPS(gadget_info);
+
+static struct configfs_item_operations gadget_root_item_ops = {
+       .release                = gadget_info_attr_release,
+       .show_attribute         = gadget_info_attr_show,
+       .store_attribute        = gadget_info_attr_store,
+};
+
+static void gadget_config_attr_release(struct config_item *item)
+{
+       struct config_usb_cfg *cfg = to_config_usb_cfg(item);
+
+       list_del(&cfg->c.list);
+       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 config_group *group = to_config_group(usb_func_ci);
+       struct usb_function_instance *fi = container_of(group,
+                       struct usb_function_instance, group);
+       struct usb_function *f;
+
+       f = usb_get_function(fi);
+       usb_put_function(f);
+       pr_err("%s() created a valid function? %d for cfg %p\n", __func__,
+                       !IS_ERR(f), cfg);
+       return -EINVAL;
+}
+
+static int 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 config_group *group = to_config_group(usb_func_ci);
+       struct usb_function_instance *fi = container_of(group,
+                       struct usb_function_instance, group);
+       /* usb_put_function(f) */
+       return 0;
+}
+
+CONFIGFS_ATTR_OPS(config_usb_cfg);
+
+static struct configfs_item_operations gadget_config_item_ops = {
+       .release                = gadget_config_attr_release,
+       .show_attribute         = config_usb_cfg_attr_show,
+       .store_attribute        = config_usb_cfg_attr_store,
+       .allow_link             = config_usb_cfg_link,
+       .drop_link              = config_usb_cfg_unlink,
+};
+
+
+static ssize_t gadget_config_desc_MaxPower_show(struct config_usb_cfg *cfg, 
char *page)
+{
+       return sprintf(page, "%u\n", cfg->c.MaxPower);
+}
+
+static ssize_t gadget_config_desc_MaxPower_store(struct config_usb_cfg *cfg,
+               const char *page, size_t len)
+{
+       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_usb_cfg 
*cfg, char *page)
+{
+       return sprintf(page, "0x%02x\n", cfg->c.bmAttributes);
+}
+
+static ssize_t gadget_config_desc_bmAttributes_store(struct config_usb_cfg 
*cfg,
+               const char *page, size_t len)
+{
+       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;
+}
+
+#define CFG_CONFIG_DESC_ITEM_ATTR(name)        \
+       static struct config_usb_cfg_attribute gadget_usb_cfg_##name = \
+               __CONFIGFS_ATTR(name,  S_IRUGO | S_IWUSR,               \
+                               gadget_config_desc_##name##_show,       \
+                               gadget_config_desc_##name##_store)
+
+CFG_CONFIG_DESC_ITEM_ATTR(MaxPower);
+CFG_CONFIG_DESC_ITEM_ATTR(bmAttributes);
+
+static struct configfs_attribute *gadget_config_attrs[] = {
+       &gadget_usb_cfg_MaxPower.attr,
+       &gadget_usb_cfg_bmAttributes.attr,
+       NULL,
+};
+
+static struct config_item_type gadget_config_type = {
+       .ct_item_ops    = &gadget_config_item_ops,
+       .ct_attrs       = gadget_config_attrs,
+       .ct_owner       = THIS_MODULE,
+};
+
+static 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);
+}
+
+static struct config_group *function_make(
+               struct config_group *group,
+               const char *name)
+{
+       struct usb_function_instance *fi;
+       char buf[MAX_NAME_LEN];
+       char *func_name;
+       char *instance_name;
+       int ret;
+
+       ret = snprintf(buf, MAX_NAME_LEN, "%s", name);
+       if (ret >= MAX_NAME_LEN)
+               ERR_PTR(-ENAMETOOLONG);
+
+       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_PTR(PTR_ERR(fi));
+
+       return &fi->group;
+}
+
+static void function_drop(
+               struct config_group *group,
+               struct config_item *item)
+{
+       /* XXX release */
+       config_item_put(item);
+}
+
+static struct configfs_group_operations functions_ops = {
+       .make_group     = &function_make,
+       .drop_item      = &function_drop,
+};
+
+static struct config_item_type functions_type = {
+       .ct_group_ops   = &functions_ops,
+       .ct_owner       = THIS_MODULE,
+};
+
+static struct config_group func_group = {
+       .cg_item = {
+               .ci_namebuf = "functions",
+               .ci_type = &functions_type,
+       },
+};
+
+CONFIGFS_ATTR_STRUCT(gadget_config_name);
+GS_STRINGS_RW(gadget_config_name, configuration);
+
+static struct configfs_attribute *gadget_config_name_langid_attrs[] = {
+       &gadget_config_name_configuration.attr,
+       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 usb_configuration *c;
+       struct config_usb_cfg *cfg;
+       char buf[MAX_NAME_LEN];
+       char *num_str;
+       u8 num;
+       int ret;
+
+       gi = container_of(group, struct gadget_info, config_group);
+       ret = snprintf(buf, MAX_NAME_LEN, "%s", name);
+       if (ret >= MAX_NAME_LEN)
+               return ERR_PTR(-ENAMETOOLONG);
+
+       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);
+
+       if (!num)
+               return ERR_PTR(-EINVAL);
+
+       list_for_each_entry(c, &gi->cdev.configs, list) {
+               if (c->bConfigurationValue == num)
+                       return ERR_PTR(-EEXIST);
+       }
+
+       cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
+       if (!cfg)
+               return ERR_PTR(-ENOMEM);
+       cfg->c.label = "configfs-configuration";
+       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);
+
+       cfg->group.default_groups = cfg->default_groups;
+       cfg->default_groups[0] = &cfg->strings_group;
+
+       config_group_init_type_name(&cfg->group, "",
+                               &gadget_config_type);
+       config_group_init_type_name(&cfg->strings_group, "strings",
+                       &gadget_config_name_strings_type);
+
+       list_add_tail(&cfg->c.list, &gi->cdev.configs);
+
+       return &cfg->group;
+}
+
+static void config_desc_drop(
+               struct config_group *group,
+               struct config_item *item)
+{
+       config_item_put(item);
+}
+
+static struct configfs_group_operations config_desc_ops = {
+       .make_group     = &config_desc_make,
+       .drop_item      = &config_desc_drop,
+};
+
+static struct config_item_type config_desc_type = {
+       .ct_group_ops   = &config_desc_ops,
+       .ct_owner       = THIS_MODULE,
+};
+
+CONFIGFS_ATTR_STRUCT(gadget_strings);
+GS_STRINGS_RW(gadget_strings, manufacturer);
+GS_STRINGS_RW(gadget_strings, product);
+GS_STRINGS_RW(gadget_strings, serialnumber);
+
+static struct configfs_attribute *gadget_strings_langid_attrs[] = {
+       &gadget_strings_manufacturer.attr,
+       &gadget_strings_product.attr,
+       &gadget_strings_serialnumber.attr,
+       NULL,
+};
+
+static void gadget_strings_attr_release(struct config_item *item)
+{
+       struct gadget_strings *gs = to_gadget_strings(item);
+
+       kfree(gs->manufacturer);
+       kfree(gs->product);
+       kfree(gs->serialnumber);
+
+       list_del(&gs->list);
+       kfree(gs);
+}
+
+USB_CONFIG_STRING_RW_OPS(gadget_strings);
+USB_CONFIG_STRINGS_LANG(gadget_strings, gadget_info);
+
+static struct config_group *gadgets_make(
+               struct config_group *group,
+               const char *name)
+{
+       struct gadget_info *gi;
+
+       gi = kzalloc(sizeof(*gi), GFP_KERNEL);
+       if (!gi)
+               return ERR_PTR(-ENOMEM);
+
+       gi->group.default_groups = gi->default_groups;
+       gi->group.default_groups[0] = &func_group,
+       gi->group.default_groups[1] = &gi->config_group;
+       gi->group.default_groups[2] = &gi->strings_group;
+
+       config_group_init_type_name(&gi->config_group, "configs",
+                       &config_desc_type);
+       config_group_init_type_name(&gi->strings_group, "strings",
+                       &gadget_strings_strings_type);
+
+       gi->device_desc.bLength = USB_DT_DEVICE_SIZE;
+       gi->device_desc.bDescriptorType = USB_DT_DEVICE;
+
+       gi->driver.dev = &gi->device_desc;
+       gi->driver.bind = NULL;
+       gi->driver.unbind = NULL;
+       gi->driver.suspend = NULL;
+       gi->driver.resume = NULL;
+       gi->driver.max_speed = USB_SPEED_SUPER;
+
+       INIT_LIST_HEAD(&gi->string_list);
+       composite_init_dev(&gi->cdev);
+       /* gi->composite.gadget_driver = composite_driver_template; */
+
+#ifdef CONFIG_USB_OTG
+       gi->otg.bLength = sizeof(struct usb_otg_descriptor);
+       gi->otg.bDescriptorType = USB_DT_OTG;
+       gi->otg.bmAttributes = USB_OTG_SRP | USB_OTG_HNP;
+#endif
+
+       config_group_init_type_name(&gi->group, "",
+                               &gadget_root_type);
+       return &gi->group;
+}
+
+static void gadgets_drop(struct config_group *group, struct config_item *item)
+{
+       config_item_put(item);
+}
+
+static struct configfs_group_operations gadgets_ops = {
+       .make_group     = &gadgets_make,
+       .drop_item      = &gadgets_drop,
+};
+
+static struct config_item_type gadgets_type = {
+       .ct_group_ops   = &gadgets_ops,
+       .ct_owner       = THIS_MODULE,
+};
+
+static struct config_group gadget_group = {
+       .cg_item = {
+               .ci_namebuf = "gadgets",
+               .ci_type = &gadgets_type,
+       },
+};
+
+static struct config_group *root_groups[] = {
+       &gadget_group,
+       &udc_group,
+       NULL
+};
+
+static struct configfs_subsystem gadget_subsys = {
+       .su_group = {
+               .cg_item = {
+                       .ci_namebuf = "usb_gadget",
+                       .ci_type = &gadget_core_type,
+               },
+               .default_groups = root_groups,
+       },
+       .su_mutex = __MUTEX_INITIALIZER(gadget_subsys.su_mutex),
+};
+
+struct udc_configfs {
+       struct config_group group;
+};
+
+struct config_group *udc_add_configfs(struct device *dev)
+{
+       struct udc_configfs *udc_cfs;
+       struct config_group *group;
+       int ret;
+
+       udc_cfs = kzalloc(sizeof(struct udc_configfs), GFP_KERNEL);
+       if (!udc_cfs)
+               return ERR_PTR(-ENOMEM);
+
+       group = &udc_cfs->group;
+       config_group_init_type_name(group,
+                       kobject_name(&dev->kobj),
+                       &gadget_core_type);
+       ret = configfs_create_group(&udc_group, group);
+       if (ret)
+               goto err;
+       return group;
+err:
+       kfree(udc_cfs);
+       return ERR_PTR(ret);
+}
+
+void udc_del_configfs(struct config_group *group)
+{
+       struct udc_configfs *udc_cfs;
+
+       udc_cfs = container_of(group, struct udc_configfs, group);
+
+       configfs_remove_group(group);
+       kfree(udc_cfs);
+}
+
+int __init gadget_cfs_init(void)
+{
+       int ret;
+
+       config_group_init(&gadget_subsys.su_group);
+       config_group_init(&func_group);
+       config_group_init(&gadget_group);
+       config_group_init(&udc_group);
+
+       ret = configfs_register_subsystem(&gadget_subsys);
+       return ret;
+}
+
+void __exit gadget_cfs_exit(void)
+{
+       configfs_unregister_subsystem(&gadget_subsys);
+}
diff --git a/drivers/usb/gadget/f_acm.c b/drivers/usb/gadget/f_acm.c
index 1a82ef7..6534ebe 100644
--- a/drivers/usb/gadget/f_acm.c
+++ b/drivers/usb/gadget/f_acm.c
@@ -760,6 +760,61 @@ static void acm_free_func(struct usb_function *f)
        acm_unbind(NULL, f);
 }
 
+static inline struct f_serial_opts *to_f_serial_opts(struct config_item *item)
+{
+       return container_of(to_config_group(item), struct f_serial_opts,
+                       func_inst.group);
+}
+
+CONFIGFS_ATTR_STRUCT(f_serial_opts);
+static ssize_t f_acm_attr_show(struct config_item *item,
+                                struct configfs_attribute *attr,
+                                char *page)
+{
+       struct f_serial_opts *opts = to_f_serial_opts(item);
+       struct f_serial_opts_attribute *f_serial_opts_attr =
+               container_of(attr, struct f_serial_opts_attribute, attr);
+       ssize_t ret = 0;
+
+       if (f_serial_opts_attr->show)
+               ret = f_serial_opts_attr->show(opts, page);
+       return ret;
+}
+
+static void acm_attr_release(struct config_item *item)
+{
+       struct f_serial_opts *opts = to_f_serial_opts(item);
+
+       usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations acm_item_ops = {
+       .release                = acm_attr_release,
+       .show_attribute         = f_acm_attr_show,
+};
+
+static ssize_t f_acm_port_num_show(struct f_serial_opts *opts, char *page)
+{
+       return sprintf(page, "%u\n", opts->port_num);
+}
+
+static struct f_serial_opts_attribute f_acm_port_num =
+       __CONFIGFS_ATTR_RO(port_num, f_acm_port_num_show);
+
+
+static struct configfs_attribute *acm_attrs[] = {
+       &f_acm_port_num.attr,
+       NULL,
+};
+
+static struct config_item_type acm_func_type = {
+       .ct_item_ops    = &acm_item_ops,
+       .ct_attrs       = acm_attrs,
+       .ct_owner       = THIS_MODULE,
+};
+
+static int dumb_port_counter;
+
 static struct usb_function *acm_alloc_func(struct usb_function_instance *fi)
 {
        struct f_serial_opts *opts;
@@ -792,6 +847,9 @@ static struct usb_function_instance 
*acm_alloc_instance(void)
        if (!opts)
                return ERR_PTR(-ENOMEM);
        opts->func_inst.free_func_inst = acm_free_instance;
+       config_group_init_type_name(&opts->func_inst.group, "",
+                       &acm_func_type);
+       opts->port_num = dumb_port_counter++;
        return &opts->func_inst;
 }
 DECLARE_USB_FUNCTION_INIT(acm, acm_alloc_instance, acm_alloc_func);
diff --git a/drivers/usb/gadget/udc-core.c b/drivers/usb/gadget/udc-core.c
index 4d90a80..48ca094 100644
--- a/drivers/usb/gadget/udc-core.c
+++ b/drivers/usb/gadget/udc-core.c
@@ -26,6 +26,7 @@
 
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
+#include <linux/configfs.h>
 
 /**
  * struct usb_udc - describes one usb device controller
@@ -42,6 +43,7 @@ struct usb_udc {
        struct usb_gadget               *gadget;
        struct device                   dev;
        struct list_head                list;
+       struct config_group             *group;
 };
 
 static struct class *udc_class;
@@ -231,6 +233,7 @@ int usb_add_gadget_udc(struct device *parent, struct 
usb_gadget *gadget)
        if (ret)
                goto err3;
 
+       udc->group = udc_add_configfs(&udc->dev);
        mutex_unlock(&udc_lock);
 
        return 0;
@@ -305,6 +308,7 @@ void usb_del_gadget_udc(struct usb_gadget *gadget)
                usb_gadget_remove_driver(udc);
 
        kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
+       udc_del_configfs(udc->group);
        device_unregister(&udc->dev);
 }
 EXPORT_SYMBOL_GPL(usb_del_gadget_udc);
@@ -504,6 +508,8 @@ static int usb_udc_uevent(struct device *dev, struct 
kobj_uevent_env *env)
 
 static int __init usb_udc_init(void)
 {
+       int ret __maybe_unused;
+
        udc_class = class_create(THIS_MODULE, "udc");
        if (IS_ERR(udc_class)) {
                pr_err("failed to create udc class --> %ld\n",
@@ -512,12 +518,30 @@ static int __init usb_udc_init(void)
        }
 
        udc_class->dev_uevent = usb_udc_uevent;
+#ifdef MODULE
+       ret = gadget_cfs_init();
+       if (ret)
+               class_destroy(udc_class);
+       return ret;
+#else
        return 0;
+#endif
 }
 subsys_initcall(usb_udc_init);
 
+#ifndef MODULE
+static int __init usb_udc_init_mod(void)
+{
+       if (IS_ERR(udc_class))
+               return PTR_ERR(udc_class);
+       return gadget_cfs_init();
+}
+module_init(usb_udc_init_mod);
+#endif
+
 static void __exit usb_udc_exit(void)
 {
+       gadget_cfs_exit();
        class_destroy(udc_class);
 }
 module_exit(usb_udc_exit);
diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index dd1db1b..7a7eed5 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -39,6 +39,7 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 #include <linux/log2.h>
+#include <linux/configfs.h>
 
 /*
  * USB function drivers should return USB_GADGET_DELAYED_STATUS if they
@@ -120,7 +121,6 @@ struct usb_configuration;
  * two or more distinct instances within the same configuration, providing
  * several independent logical data links to a USB host.
  */
-
 struct usb_function {
        const char                      *name;
        struct usb_gadget_strings       **strings;
@@ -447,6 +447,7 @@ struct usb_function_driver {
 };
 
 struct usb_function_instance {
+       struct config_group group;
        struct usb_function_driver *fd;
        void (*free_func_inst)(struct usb_function_instance *inst);
 };
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 0af6569..6f5fe20 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -883,6 +883,11 @@ extern void usb_del_gadget_udc(struct usb_gadget *gadget);
 
 /*-------------------------------------------------------------------------*/
 
+struct config_group *udc_add_configfs(struct device *dev);
+void udc_del_configfs(struct config_group *group);
+int gadget_cfs_init(void);
+void __exit gadget_cfs_exit(void);
+
 /* utility to simplify dealing with string descriptors */
 
 /**
diff --git a/include/linux/usb/gadget_configfs.h 
b/include/linux/usb/gadget_configfs.h
new file mode 100644
index 0000000..efbbadf
--- /dev/null
+++ b/include/linux/usb/gadget_configfs.h
@@ -0,0 +1,109 @@
+#ifndef __GADGET_CONFIGFS__
+#define __GADGET_CONFIGFS__
+
+#include <linux/configfs.h>
+
+int check_user_usb_string(const char *name,
+               struct usb_gadget_strings *stringtab_dev);
+
+#define GS_STRINGS_W(__struct, __name) \
+       static ssize_t __struct##_##__name##_store(struct __struct *gs, \
+               const char *page, size_t len)           \
+{                                                      \
+       int ret;                                        \
+                                                       \
+       ret = usb_string_copy(page, &gs->__name);       \
+       if (ret)                                        \
+               return ret;                             \
+       return len;                                     \
+}
+
+#define GS_STRINGS_R(__struct, __name) \
+       static ssize_t __struct##_##__name##_show(struct __struct *gs, char 
*page)      \
+{      \
+       return sprintf(page, "%s\n", gs->__name);       \
+}
+
+#define GS_STRING_ITEM_ATTR(struct_name, name) \
+       static struct struct_name##_attribute struct_name##_##name = \
+               __CONFIGFS_ATTR(name,  S_IRUGO | S_IWUSR,               \
+                               struct_name##_##name##_show,            \
+                               struct_name##_##name##_store)
+
+#define GS_STRINGS_RW(struct_name, _name)      \
+       GS_STRINGS_R(struct_name, _name)        \
+       GS_STRINGS_W(struct_name, _name)        \
+       GS_STRING_ITEM_ATTR(struct_name, _name)
+
+#define USB_CONFIG_STRING_RW_OPS(struct_in)                            \
+       CONFIGFS_ATTR_OPS(struct_in);                                   \
+                                                                       \
+static struct configfs_item_operations struct_in##_langid_item_ops = { \
+       .release                = struct_in##_attr_release,             \
+       .show_attribute         = struct_in##_attr_show,                \
+       .store_attribute        = struct_in##_attr_store,               \
+};                                                                     \
+                                                                       \
+static struct config_item_type struct_in##_langid_type = {             \
+       .ct_item_ops    = &struct_in##_langid_item_ops,                 \
+       .ct_attrs       = struct_in##_langid_attrs,                     \
+       .ct_owner       = THIS_MODULE,                                  \
+}
+
+#define USB_CONFIG_STRINGS_LANG(struct_in, struct_member)      \
+       static struct config_group *struct_in##_strings_make(           \
+                       struct config_group *group,                     \
+                       const char *name)                               \
+       {                                                               \
+       struct struct_member *gi;                                       \
+       struct struct_in *gs;                                           \
+       struct struct_in *new;                                          \
+       int langs = 0;                                                  \
+       int ret;                                                        \
+                                                                       \
+       new = kzalloc(sizeof(*new), GFP_KERNEL);                        \
+       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, "",                    \
+                       &struct_in##_langid_type);                      \
+                                                                       \
+       gi = container_of(group, struct struct_member, 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);                    \
+       return &new->group;                                             \
+err:                                                                   \
+       kfree(new);                                                     \
+       return ERR_PTR(ret);                                            \
+}                                                                      \
+                                                                       \
+static void struct_in##_strings_drop(                                  \
+               struct config_group *group,                             \
+               struct config_item *item)                               \
+{                                                                      \
+       config_item_put(item);                                          \
+}                                                                      \
+                                                                       \
+static struct configfs_group_operations struct_in##_strings_ops = {    \
+       .make_group     = &struct_in##_strings_make,                    \
+       .drop_item      = &struct_in##_strings_drop,                    \
+};                                                                     \
+                                                                       \
+static struct config_item_type struct_in##_strings_type = {            \
+       .ct_group_ops   = &struct_in##_strings_ops,                     \
+       .ct_owner       = THIS_MODULE,                                  \
+}
+
+#endif
-- 
1.7.10.4

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