drivers/iio/industrialio-sw-trigger.c

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