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 int 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");