drivers/iio/industrialio-sw-device.c

   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");