1 /*
2  * The Industrial I/O core, software IIO devices functions
3  *
4  * Copyright (c) 2016 Intel Corporation
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License version 2 as published by
8  * the Free Software Foundation.
9  */
10 
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/kmod.h>
14 #include <linux/list.h>
15 #include <linux/slab.h>
16 
17 #include <linux/iio/sw_device.h>
18 #include <linux/iio/configfs.h>
19 #include <linux/configfs.h>
20 
21 static struct config_group *iio_devices_group;
22 static struct config_item_type iio_device_type_group_type;
23 
24 static struct config_item_type iio_devices_group_type = {
25 	.ct_owner = THIS_MODULE,
26 };
27 
28 static LIST_HEAD(iio_device_types_list);
29 static DEFINE_MUTEX(iio_device_types_lock);
30 
31 static
32 struct iio_sw_device_type *__iio_find_sw_device_type(const char *name,
33 						     unsigned len)
34 {
35 	struct iio_sw_device_type *d = NULL, *iter;
36 
37 	list_for_each_entry(iter, &iio_device_types_list, list)
38 		if (!strcmp(iter->name, name)) {
39 			d = iter;
40 			break;
41 		}
42 
43 	return d;
44 }
45 
46 int iio_register_sw_device_type(struct iio_sw_device_type *d)
47 {
48 	struct iio_sw_device_type *iter;
49 	int ret = 0;
50 
51 	mutex_lock(&iio_device_types_lock);
52 	iter = __iio_find_sw_device_type(d->name, strlen(d->name));
53 	if (iter)
54 		ret = -EBUSY;
55 	else
56 		list_add_tail(&d->list, &iio_device_types_list);
57 	mutex_unlock(&iio_device_types_lock);
58 
59 	if (ret)
60 		return ret;
61 
62 	d->group = configfs_register_default_group(iio_devices_group, d->name,
63 						&iio_device_type_group_type);
64 	if (IS_ERR(d->group))
65 		ret = PTR_ERR(d->group);
66 
67 	return ret;
68 }
69 EXPORT_SYMBOL(iio_register_sw_device_type);
70 
71 void iio_unregister_sw_device_type(struct iio_sw_device_type *dt)
72 {
73 	struct iio_sw_device_type *iter;
74 
75 	mutex_lock(&iio_device_types_lock);
76 	iter = __iio_find_sw_device_type(dt->name, strlen(dt->name));
77 	if (iter)
78 		list_del(&dt->list);
79 	mutex_unlock(&iio_device_types_lock);
80 
81 	configfs_unregister_default_group(dt->group);
82 }
83 EXPORT_SYMBOL(iio_unregister_sw_device_type);
84 
85 static
86 struct iio_sw_device_type *iio_get_sw_device_type(const char *name)
87 {
88 	struct iio_sw_device_type *dt;
89 
90 	mutex_lock(&iio_device_types_lock);
91 	dt = __iio_find_sw_device_type(name, strlen(name));
92 	if (dt && !try_module_get(dt->owner))
93 		dt = NULL;
94 	mutex_unlock(&iio_device_types_lock);
95 
96 	return dt;
97 }
98 
99 struct iio_sw_device *iio_sw_device_create(const char *type, const char *name)
100 {
101 	struct iio_sw_device *d;
102 	struct iio_sw_device_type *dt;
103 
104 	dt = iio_get_sw_device_type(type);
105 	if (!dt) {
106 		pr_err("Invalid device type: %s\n", type);
107 		return ERR_PTR(-EINVAL);
108 	}
109 	d = dt->ops->probe(name);
110 	if (IS_ERR(d))
111 		goto out_module_put;
112 
113 	d->device_type = dt;
114 
115 	return d;
116 out_module_put:
117 	module_put(dt->owner);
118 	return d;
119 }
120 EXPORT_SYMBOL(iio_sw_device_create);
121 
122 void iio_sw_device_destroy(struct iio_sw_device *d)
123 {
124 	struct iio_sw_device_type *dt = d->device_type;
125 
126 	dt->ops->remove(d);
127 	module_put(dt->owner);
128 }
129 EXPORT_SYMBOL(iio_sw_device_destroy);
130 
131 static struct config_group *device_make_group(struct config_group *group,
132 					      const char *name)
133 {
134 	struct iio_sw_device *d;
135 
136 	d = iio_sw_device_create(group->cg_item.ci_name, name);
137 	if (IS_ERR(d))
138 		return ERR_CAST(d);
139 
140 	config_item_set_name(&d->group.cg_item, "%s", name);
141 
142 	return &d->group;
143 }
144 
145 static void device_drop_group(struct config_group *group,
146 			      struct config_item *item)
147 {
148 	struct iio_sw_device *d = to_iio_sw_device(item);
149 
150 	iio_sw_device_destroy(d);
151 	config_item_put(item);
152 }
153 
154 static struct configfs_group_operations device_ops = {
155 	.make_group	= &device_make_group,
156 	.drop_item	= &device_drop_group,
157 };
158 
159 static struct config_item_type iio_device_type_group_type = {
160 	.ct_group_ops = &device_ops,
161 	.ct_owner       = THIS_MODULE,
162 };
163 
164 static int __init iio_sw_device_init(void)
165 {
166 	iio_devices_group =
167 		configfs_register_default_group(&iio_configfs_subsys.su_group,
168 						"devices",
169 						&iio_devices_group_type);
170 	return PTR_ERR_OR_ZERO(iio_devices_group);
171 }
172 module_init(iio_sw_device_init);
173 
174 static void __exit iio_sw_device_exit(void)
175 {
176 	configfs_unregister_default_group(iio_devices_group);
177 }
178 module_exit(iio_sw_device_exit);
179 
180 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
181 MODULE_DESCRIPTION("Industrial I/O software devices support");
182 MODULE_LICENSE("GPL v2");
183