GNU Linux-libre 5.19-rc6-gnu
[releases.git] / drivers / iio / industrialio-sw-trigger.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * The Industrial I/O core, software trigger functions
4  *
5  * Copyright (c) 2015 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_trigger.h>
15 #include <linux/iio/configfs.h>
16 #include <linux/configfs.h>
17
18 static struct config_group *iio_triggers_group;
19 static const struct config_item_type iio_trigger_type_group_type;
20
21 static const struct config_item_type iio_triggers_group_type = {
22         .ct_owner = THIS_MODULE,
23 };
24
25 static LIST_HEAD(iio_trigger_types_list);
26 static DEFINE_MUTEX(iio_trigger_types_lock);
27
28 static
29 struct iio_sw_trigger_type *__iio_find_sw_trigger_type(const char *name,
30                                                        unsigned len)
31 {
32         struct iio_sw_trigger_type *t = NULL, *iter;
33
34         list_for_each_entry(iter, &iio_trigger_types_list, list)
35                 if (!strcmp(iter->name, name)) {
36                         t = iter;
37                         break;
38                 }
39
40         return t;
41 }
42
43 int iio_register_sw_trigger_type(struct iio_sw_trigger_type *t)
44 {
45         struct iio_sw_trigger_type *iter;
46         int ret = 0;
47
48         mutex_lock(&iio_trigger_types_lock);
49         iter = __iio_find_sw_trigger_type(t->name, strlen(t->name));
50         if (iter)
51                 ret = -EBUSY;
52         else
53                 list_add_tail(&t->list, &iio_trigger_types_list);
54         mutex_unlock(&iio_trigger_types_lock);
55
56         if (ret)
57                 return ret;
58
59         t->group = configfs_register_default_group(iio_triggers_group, t->name,
60                                                 &iio_trigger_type_group_type);
61         if (IS_ERR(t->group))
62                 ret = PTR_ERR(t->group);
63
64         return ret;
65 }
66 EXPORT_SYMBOL(iio_register_sw_trigger_type);
67
68 void iio_unregister_sw_trigger_type(struct iio_sw_trigger_type *t)
69 {
70         struct iio_sw_trigger_type *iter;
71
72         mutex_lock(&iio_trigger_types_lock);
73         iter = __iio_find_sw_trigger_type(t->name, strlen(t->name));
74         if (iter)
75                 list_del(&t->list);
76         mutex_unlock(&iio_trigger_types_lock);
77
78         configfs_unregister_default_group(t->group);
79 }
80 EXPORT_SYMBOL(iio_unregister_sw_trigger_type);
81
82 static
83 struct iio_sw_trigger_type *iio_get_sw_trigger_type(const char *name)
84 {
85         struct iio_sw_trigger_type *t;
86
87         mutex_lock(&iio_trigger_types_lock);
88         t = __iio_find_sw_trigger_type(name, strlen(name));
89         if (t && !try_module_get(t->owner))
90                 t = NULL;
91         mutex_unlock(&iio_trigger_types_lock);
92
93         return t;
94 }
95
96 struct iio_sw_trigger *iio_sw_trigger_create(const char *type, const char *name)
97 {
98         struct iio_sw_trigger *t;
99         struct iio_sw_trigger_type *tt;
100
101         tt = iio_get_sw_trigger_type(type);
102         if (!tt) {
103                 pr_err("Invalid trigger type: %s\n", type);
104                 return ERR_PTR(-EINVAL);
105         }
106         t = tt->ops->probe(name);
107         if (IS_ERR(t))
108                 goto out_module_put;
109
110         t->trigger_type = tt;
111
112         return t;
113 out_module_put:
114         module_put(tt->owner);
115         return t;
116 }
117 EXPORT_SYMBOL(iio_sw_trigger_create);
118
119 void iio_sw_trigger_destroy(struct iio_sw_trigger *t)
120 {
121         struct iio_sw_trigger_type *tt = t->trigger_type;
122
123         tt->ops->remove(t);
124         module_put(tt->owner);
125 }
126 EXPORT_SYMBOL(iio_sw_trigger_destroy);
127
128 static struct config_group *trigger_make_group(struct config_group *group,
129                                                const char *name)
130 {
131         struct iio_sw_trigger *t;
132
133         t = iio_sw_trigger_create(group->cg_item.ci_name, name);
134         if (IS_ERR(t))
135                 return ERR_CAST(t);
136
137         config_item_set_name(&t->group.cg_item, "%s", name);
138
139         return &t->group;
140 }
141
142 static void trigger_drop_group(struct config_group *group,
143                                struct config_item *item)
144 {
145         struct iio_sw_trigger *t = to_iio_sw_trigger(item);
146
147         iio_sw_trigger_destroy(t);
148         config_item_put(item);
149 }
150
151 static struct configfs_group_operations trigger_ops = {
152         .make_group     = &trigger_make_group,
153         .drop_item      = &trigger_drop_group,
154 };
155
156 static const struct config_item_type iio_trigger_type_group_type = {
157         .ct_group_ops = &trigger_ops,
158         .ct_owner       = THIS_MODULE,
159 };
160
161 static int __init iio_sw_trigger_init(void)
162 {
163         iio_triggers_group =
164                 configfs_register_default_group(&iio_configfs_subsys.su_group,
165                                                 "triggers",
166                                                 &iio_triggers_group_type);
167         return PTR_ERR_OR_ZERO(iio_triggers_group);
168 }
169 module_init(iio_sw_trigger_init);
170
171 static void __exit iio_sw_trigger_exit(void)
172 {
173         configfs_unregister_default_group(iio_triggers_group);
174 }
175 module_exit(iio_sw_trigger_exit);
176
177 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
178 MODULE_DESCRIPTION("Industrial I/O software triggers support");
179 MODULE_LICENSE("GPL v2");