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");
180