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);
118