1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * The Industrial I/O core, software IIO devices functions
4  *
5  * Copyright (c) 2016 Intel Corporation
6  */
7 
8 #include <linux/module.h>
9 #include <linux/init.h>
10 #include <linux/kmod.h>
11 #include <linux/list.h>
12 #include <linux/slab.h>
13 
14 #include <linux/iio/sw_device.h>
15 #include <linux/iio/configfs.h>
16 #include <linux/configfs.h>
17 
18 static struct config_group *iio_devices_group;
19 static const struct config_item_type iio_device_type_group_type;
20 
21 static const struct config_item_type iio_devices_group_type = {
22 	.ct_owner = THIS_MODULE,
23 };
24 
25 static LIST_HEAD(iio_device_types_list);
26 static DEFINE_MUTEX(iio_device_types_lock);
27 
28 static
29 struct iio_sw_device_type *__iio_find_sw_device_type(const char *name,
30 						     unsigned len)
31 {
32 	struct iio_sw_device_type *d = NULL, *iter;
33 
34 	list_for_each_entry(iter, &iio_device_types_list, list)
35 		if (!strcmp(iter->name, name)) {
36 			d = iter;
37 			break;
38 		}
39 
40 	return d;
41 }
42 
43 int iio_register_sw_device_type(struct iio_sw_device_type *d)
44 {
45 	struct iio_sw_device_type *iter;
46 	int ret = 0;
47 
48 	mutex_lock(&iio_device_types_lock);
49 	iter = __iio_find_sw_device_type(d->name, strlen(d->name));
50 	if (iter)
51 		ret = -EBUSY;
52 	else
53 		list_add_tail(&d->list, &iio_device_types_list);
54 	mutex_unlock(&iio_device_types_lock);
55 
56 	if (ret)
57 		return ret;
58 
59 	d->group = configfs_register_default_group(iio_devices_group, d->name,
60 						&iio_device_type_group_type);
61 	if (IS_ERR(d->group))
62 		ret = PTR_ERR(d->group);
63 
64 	return ret;
65 }
66 EXPORT_SYMBOL(iio_register_sw_device_type);
67 
68 void iio_unregister_sw_device_type(struct iio_sw_device_type *dt)
69 {
70 	struct iio_sw_device_type *iter;
71 
72 	mutex_lock(&iio_device_types_lock);
73 	iter = __iio_find_sw_device_type(dt->name, strlen(dt->name));
74 	if (iter)
75 		list_del(&dt->list);
76 	mutex_unlock(&iio_device_types_lock);
77 
78 	configfs_unregister_default_group(dt->group);
79 }
80 EXPORT_SYMBOL(iio_unregister_sw_device_type);
81 
82 static
83 struct iio_sw_device_type *iio_get_sw_device_type(const char *name)
84 {
85 	struct iio_sw_device_type *dt;
86 
87 	mutex_lock(&iio_device_types_lock);
88 	dt = __iio_find_sw_device_type(name, strlen(name));
89 	if (dt && !try_module_get(dt->owner))
90 		dt = NULL;
91 	mutex_unlock(&iio_device_types_lock);
92 
93 	return dt;
94 }
95 
96 struct iio_sw_device *iio_sw_device_create(const char *type, const char *name)
97 {
98 	struct iio_sw_device *d;
99 	struct iio_sw_device_type *dt;
100 
101 	dt = iio_get_sw_device_type(type);
102 	if (!dt) {
103 		pr_err("Invalid device type: %s\n", type);
104 		return ERR_PTR(-EINVAL);
105 	}
106 	d = dt->ops->probe(name);
107 	if (IS_ERR(d))
108 		goto out_module_put;
109 
110 	d->device_type = dt;
111 
112 	return d;
113 out_module_put:
114 	module_put(dt->owner);
115 	return d;
116 }
117 EXPORT_SYMBOL(iio_sw_device_create);
118 
119 void iio_sw_device_destroy(struct iio_sw_device *d)
120 {
121 	struct iio_sw_device_type *dt = d->device_type;
122 
123 	dt->ops->remove(d);
124 	module_put(dt->owner);
125 }
126 EXPORT_SYMBOL(iio_sw_device_destroy);
127 
128 static struct config_group *device_make_group(struct config_group *group,
129 					      const char *name)
130 {
131 	struct iio_sw_device *d;
132 
133 	d = iio_sw_device_create(group->cg_item.ci_name, name);
134 	if (IS_ERR(d))
135 		return ERR_CAST(d);
136 
137 	config_item_set_name(&d->group.cg_item, "%s", name);
138 
139 	return &d->group;
140 }
141 
142 static void device_drop_group(struct config_group *group,
143 			      struct config_item *item)
144 {
145 	struct iio_sw_device *d = to_iio_sw_device(item);
146 
147 	iio_sw_device_destroy(d);
148 	config_item_put(item);
149 }
150 
151 static struct configfs_group_operations device_ops = {
152 	.make_group	= &device_make_group,
153 	.drop_item	= &device_drop_group,
154 };
155 
156 static const struct config_item_type iio_device_type_group_type = {
157 	.ct_group_ops = &device_ops,
158 	.ct_owner       = THIS_MODULE,
159 };
160 
161 static int __init iio_sw_device_init(void)
162 {
163 	iio_devices_group =
164 		configfs_register_default_group(&iio_configfs_subsys.su_group,
165 						"devices",
166 						&iio_devices_group_type);
167 	return PTR_ERR_OR_ZERO(iio_devices_group);
168 }
169 module_init(iio_sw_device_init);
170 
171 static void __exit iio_sw_device_exit(void)
172 {
173 	configfs_unregister_default_group(iio_devices_group);
174 }
175 module_exit(iio_sw_device_exit);
176 
177 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
178 MODULE_DESCRIPTION("Industrial I/O software devices support");
179 MODULE_LICENSE("GPL v2");
180