1 files changed, 116 insertions, 0 deletions

diff --git a/drivers/usb/gadget/functions.c b/drivers/usb/gadget/functions.c
new file mode 100644
index 000000000000..b13f839e7368
--- /dev/null
+++ b/drivers/usb/gadget/functions.c
@@ -0,0 +1,116 @@
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/err.h>
+
+#include <linux/usb/composite.h>
+
+static LIST_HEAD(func_list);
+static DEFINE_MUTEX(func_lock);
+
+static struct usb_function_instance *try_get_usb_function_instance(const char *name)
+{
+        struct usb_function_driver *fd;
+        struct usb_function_instance *fi;
+
+        fi = ERR_PTR(-ENOENT);
+        mutex_lock(&func_lock);
+        list_for_each_entry(fd, &func_list, list) {
+
+                if (strcmp(name, fd->name))
+                        continue;
+
+                if (!try_module_get(fd->mod)) {
+                        fi = ERR_PTR(-EBUSY);
+                        break;
+                }
+                fi = fd->alloc_inst();
+                if (IS_ERR(fi))
+                        module_put(fd->mod);
+                else
+                        fi->fd = fd;
+                break;
+        }
+        mutex_unlock(&func_lock);
+        return fi;
+}
+
+struct usb_function_instance *usb_get_function_instance(const char *name)
+{
+        struct usb_function_instance *fi;
+        int ret;
+
+        fi = try_get_usb_function_instance(name);
+        if (!IS_ERR(fi))
+                return fi;
+        ret = PTR_ERR(fi);
+        if (ret != -ENOENT)
+                return fi;
+        ret = request_module("usbfunc:%s", name);
+        if (ret < 0)
+                return ERR_PTR(ret);
+        return try_get_usb_function_instance(name);
+}
+EXPORT_SYMBOL_GPL(usb_get_function_instance);
+
+struct usb_function *usb_get_function(struct usb_function_instance *fi)
+{
+        struct usb_function *f;
+
+        f = fi->fd->alloc_func(fi);
+        if (IS_ERR(f))
+                return f;
+        f->fi = fi;
+        return f;
+}
+EXPORT_SYMBOL_GPL(usb_get_function);
+
+void usb_put_function_instance(struct usb_function_instance *fi)
+{
+        struct module *mod;
+
+        if (!fi)
+                return;
+
+        mod = fi->fd->mod;
+        fi->free_func_inst(fi);
+        module_put(mod);
+}
+EXPORT_SYMBOL_GPL(usb_put_function_instance);
+
+void usb_put_function(struct usb_function *f)
+{
+        if (!f)
+                return;
+
+        f->free_func(f);
+}
+EXPORT_SYMBOL_GPL(usb_put_function);
+
+int usb_function_register(struct usb_function_driver *newf)
+{
+        struct usb_function_driver *fd;
+        int ret;
+
+        ret = -EEXIST;
+
+        mutex_lock(&func_lock);
+        list_for_each_entry(fd, &func_list, list) {
+                if (!strcmp(fd->name, newf->name))
+                        goto out;
+        }
+        ret = 0;
+        list_add_tail(&newf->list, &func_list);
+out:
+        mutex_unlock(&func_lock);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(usb_function_register);
+
+void usb_function_unregister(struct usb_function_driver *fd)
+{
+        mutex_lock(&func_lock);
+        list_del(&fd->list);
+        mutex_unlock(&func_lock);
+}
+EXPORT_SYMBOL_GPL(usb_function_unregister);