drivers/usb/gadget/functions.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/kernel.h>
   3 #include <linux/slab.h>
   4 #include <linux/module.h>
   5 #include <linux/err.h>
   6
   7 #include <linux/usb/composite.h>
   8
   9 static LIST_HEAD(func_list);
  10 static DEFINE_MUTEX(func_lock);
  11
  12 static struct usb_function_instance *try_get_usb_function_instance(const char *name)
  13 {
  14         struct usb_function_driver *fd;
  15         struct usb_function_instance *fi;
  16
  17         fi = ERR_PTR(-ENOENT);
  18         mutex_lock(&func_lock);
  19         list_for_each_entry(fd, &func_list, list) {
  20
  21                 if (strcmp(name, fd->name))
  22                         continue;
  23
  24                 if (!try_module_get(fd->mod)) {
  25                         fi = ERR_PTR(-EBUSY);
  26                         break;
  27                 }
  28                 fi = fd->alloc_inst();
  29                 if (IS_ERR(fi))
  30                         module_put(fd->mod);
  31                 else
  32                         fi->fd = fd;
  33                 break;
  34         }
  35         mutex_unlock(&func_lock);
  36         return fi;
  37 }
  38
  39 struct usb_function_instance *usb_get_function_instance(const char *name)
  40 {
  41         struct usb_function_instance *fi;
  42         int ret;
  43
  44         fi = try_get_usb_function_instance(name);
  45         if (!IS_ERR(fi))
  46                 return fi;
  47         ret = PTR_ERR(fi);
  48         if (ret != -ENOENT)
  49                 return fi;
  50         ret = request_module("usbfunc:%s", name);
  51         if (ret < 0)
  52                 return ERR_PTR(ret);
  53         return try_get_usb_function_instance(name);
  54 }
  55 EXPORT_SYMBOL_GPL(usb_get_function_instance);
  56
  57 struct usb_function *usb_get_function(struct usb_function_instance *fi)
  58 {
  59         struct usb_function *f;
  60
  61         f = fi->fd->alloc_func(fi);
  62         if (IS_ERR(f))
  63                 return f;
  64         f->fi = fi;
  65         return f;
  66 }
  67 EXPORT_SYMBOL_GPL(usb_get_function);
  68
  69 void usb_put_function_instance(struct usb_function_instance *fi)
  70 {
  71         struct module *mod;
  72
  73         if (!fi)
  74                 return;
  75
  76         mod = fi->fd->mod;
  77         fi->free_func_inst(fi);
  78         module_put(mod);
  79 }
  80 EXPORT_SYMBOL_GPL(usb_put_function_instance);
  81
  82 void usb_put_function(struct usb_function *f)
  83 {
  84         if (!f)
  85                 return;
  86
  87         f->free_func(f);
  88 }
  89 EXPORT_SYMBOL_GPL(usb_put_function);
  90
  91 int usb_function_register(struct usb_function_driver *newf)
  92 {
  93         struct usb_function_driver *fd;
  94         int ret;
  95
  96         ret = -EEXIST;
  97
  98         mutex_lock(&func_lock);
  99         list_for_each_entry(fd, &func_list, list) {
 100                 if (!strcmp(fd->name, newf->name))
 101                         goto out;
 102         }
 103         ret = 0;
 104         list_add_tail(&newf->list, &func_list);
 105 out:
 106         mutex_unlock(&func_lock);
 107         return ret;
 108 }
 109 EXPORT_SYMBOL_GPL(usb_function_register);
 110
 111 void usb_function_unregister(struct usb_function_driver *fd)
 112 {
 113         mutex_lock(&func_lock);
 114         list_del(&fd->list);
 115         mutex_unlock(&func_lock);
 116 }
 117 EXPORT_SYMBOL_GPL(usb_function_unregister);