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
  9static LIST_HEAD(func_list);
 10static DEFINE_MUTEX(func_lock);
 11
 12static 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
 39struct 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}
 55EXPORT_SYMBOL_GPL(usb_get_function_instance);
 56
 57struct 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}
 67EXPORT_SYMBOL_GPL(usb_get_function);
 68
 69void 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}
 80EXPORT_SYMBOL_GPL(usb_put_function_instance);
 81
 82void usb_put_function(struct usb_function *f)
 83{
 84	if (!f)
 85		return;
 86
 87	f->free_func(f);
 88}
 89EXPORT_SYMBOL_GPL(usb_put_function);
 90
 91int 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);
105out:
106	mutex_unlock(&func_lock);
107	return ret;
108}
109EXPORT_SYMBOL_GPL(usb_function_register);
110
111void 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}
117EXPORT_SYMBOL_GPL(usb_function_unregister);