drivers/staging/iio/industrialio-trigger.c

   1 /* The industrial I/O core, trigger handling functions
   2  *
   3  * Copyright (c) 2008 Jonathan Cameron
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published by
   7  * the Free Software Foundation.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/idr.h>
  13 #include <linux/err.h>
  14 #include <linux/device.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/list.h>
  17 #include <linux/slab.h>
  18
  19 #include "iio.h"
  20 #include "trigger.h"
  21 #include "trigger_consumer.h"
  22
  23 /* RFC - Question of approach
  24  * Make the common case (single sensor single trigger)
  25  * simple by starting trigger capture from when first sensors
  26  * is added.
  27  *
  28  * Complex simultaneous start requires use of 'hold' functionality
  29  * of the trigger. (not implemented)
  30  *
  31  * Any other suggestions?
  32  */
  33
  34 static DEFINE_IDR(iio_trigger_idr);
  35 static DEFINE_SPINLOCK(iio_trigger_idr_lock);
  36
  37 /* Single list of all available triggers */
  38 static LIST_HEAD(iio_trigger_list);
  39 static DEFINE_MUTEX(iio_trigger_list_lock);
  40
  41 /**
  42  * iio_trigger_register_sysfs() - create a device for this trigger
  43  * @trig_info:  the trigger
  44  *
  45  * Also adds any control attribute registered by the trigger driver
  46  **/
  47 static int iio_trigger_register_sysfs(struct iio_trigger *trig_info)
  48 {
  49         int ret = 0;
  50
  51         if (trig_info->control_attrs)
  52                 ret = sysfs_create_group(&trig_info->dev.kobj,
  53                                          trig_info->control_attrs);
  54
  55         return ret;
  56 }
  57
  58 static void iio_trigger_unregister_sysfs(struct iio_trigger *trig_info)
  59 {
  60         if (trig_info->control_attrs)
  61                 sysfs_remove_group(&trig_info->dev.kobj,
  62                                    trig_info->control_attrs);
  63 }
  64
  65
  66 /**
  67  * iio_trigger_register_id() - get a unique id for this trigger
  68  * @trig_info:  the trigger
  69  **/
  70 static int iio_trigger_register_id(struct iio_trigger *trig_info)
  71 {
  72         int ret = 0;
  73
  74 idr_again:
  75         if (unlikely(idr_pre_get(&iio_trigger_idr, GFP_KERNEL) == 0))
  76                 return -ENOMEM;
  77
  78         spin_lock(&iio_trigger_idr_lock);
  79         ret = idr_get_new(&iio_trigger_idr, NULL, &trig_info->id);
  80         spin_unlock(&iio_trigger_idr_lock);
  81         if (unlikely(ret == -EAGAIN))
  82                 goto idr_again;
  83         else if (likely(!ret))
  84                 trig_info->id = trig_info->id & MAX_ID_MASK;
  85
  86         return ret;
  87 }
  88
  89 /**
  90  * iio_trigger_unregister_id() - free up unique id for use by another trigger
  91  * @trig_info: the trigger
  92  **/
  93 static void iio_trigger_unregister_id(struct iio_trigger *trig_info)
  94 {
  95         spin_lock(&iio_trigger_idr_lock);
  96         idr_remove(&iio_trigger_idr, trig_info->id);
  97         spin_unlock(&iio_trigger_idr_lock);
  98 }
  99
 100 int iio_trigger_register(struct iio_trigger *trig_info)
 101 {
 102         int ret;
 103
 104         ret = iio_trigger_register_id(trig_info);
 105         if (ret)
 106                 goto error_ret;
 107         /* Set the name used for the sysfs directory etc */
 108         dev_set_name(&trig_info->dev, "trigger%ld",
 109                      (unsigned long) trig_info->id);
 110
 111         ret = device_add(&trig_info->dev);
 112         if (ret)
 113                 goto error_unregister_id;
 114
 115         ret = iio_trigger_register_sysfs(trig_info);
 116         if (ret)
 117                 goto error_device_del;
 118
 119         /* Add to list of available triggers held by the IIO core */
 120         mutex_lock(&iio_trigger_list_lock);
 121         list_add_tail(&trig_info->list, &iio_trigger_list);
 122         mutex_unlock(&iio_trigger_list_lock);
 123
 124         return 0;
 125
 126 error_device_del:
 127         device_del(&trig_info->dev);
 128 error_unregister_id:
 129         iio_trigger_unregister_id(trig_info);
 130 error_ret:
 131         return ret;
 132 }
 133 EXPORT_SYMBOL(iio_trigger_register);
 134
 135 void iio_trigger_unregister(struct iio_trigger *trig_info)
 136 {
 137         struct iio_trigger *cursor;
 138
 139         mutex_lock(&iio_trigger_list_lock);
 140         list_for_each_entry(cursor, &iio_trigger_list, list)
 141                 if (cursor == trig_info) {
 142                         list_del(&cursor->list);
 143                         break;
 144                 }
 145         mutex_unlock(&iio_trigger_list_lock);
 146
 147         iio_trigger_unregister_sysfs(trig_info);
 148         iio_trigger_unregister_id(trig_info);
 149         /* Possible issue in here */
 150         device_unregister(&trig_info->dev);
 151 }
 152 EXPORT_SYMBOL(iio_trigger_unregister);
 153
 154 static struct iio_trigger *iio_trigger_find_by_name(const char *name,
 155                                                     size_t len)
 156 {
 157         struct iio_trigger *trig = NULL, *iter;
 158
 159         mutex_lock(&iio_trigger_list_lock);
 160         list_for_each_entry(iter, &iio_trigger_list, list)
 161                 if (sysfs_streq(iter->name, name)) {
 162                         trig = iter;
 163                         break;
 164                 }
 165         mutex_unlock(&iio_trigger_list_lock);
 166
 167         return trig;
 168 }
 169
 170 void iio_trigger_poll(struct iio_trigger *trig, s64 time)
 171 {
 172         struct iio_poll_func *pf_cursor;
 173
 174         list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
 175                 if (pf_cursor->poll_func_immediate) {
 176                         pf_cursor->poll_func_immediate(pf_cursor->private_data);
 177                         trig->use_count++;
 178                 }
 179         }
 180         list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
 181                 if (pf_cursor->poll_func_main) {
 182                         pf_cursor->poll_func_main(pf_cursor->private_data,
 183                                                   time);
 184                         trig->use_count++;
 185                 }
 186         }
 187 }
 188 EXPORT_SYMBOL(iio_trigger_poll);
 189
 190 void iio_trigger_notify_done(struct iio_trigger *trig)
 191 {
 192         trig->use_count--;
 193         if (trig->use_count == 0 && trig->try_reenable)
 194                 if (trig->try_reenable(trig)) {
 195                         /* Missed and interrupt so launch new poll now */
 196                         iio_trigger_poll(trig, 0);
 197                 }
 198 }
 199 EXPORT_SYMBOL(iio_trigger_notify_done);
 200
 201 /**
 202  * iio_trigger_read_name() - retrieve useful identifying name
 203  **/
 204 ssize_t iio_trigger_read_name(struct device *dev,
 205                               struct device_attribute *attr,
 206                               char *buf)
 207 {
 208         struct iio_trigger *trig = dev_get_drvdata(dev);
 209         return sprintf(buf, "%s\n", trig->name);
 210 }
 211 EXPORT_SYMBOL(iio_trigger_read_name);
 212
 213 /* Trigger Consumer related functions */
 214
 215 /* Complexity in here.  With certain triggers (datardy) an acknowledgement
 216  * may be needed if the pollfuncs do not include the data read for the
 217  * triggering device.
 218  * This is not currently handled.  Alternative of not enabling trigger unless
 219  * the relevant function is in there may be the best option.
 220  */
 221 /* Worth protecting against double additions?*/
 222 int iio_trigger_attach_poll_func(struct iio_trigger *trig,
 223                                  struct iio_poll_func *pf)
 224 {
 225         int ret = 0;
 226         unsigned long flags;
 227
 228         spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
 229         list_add_tail(&pf->list, &trig->pollfunc_list);
 230         spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
 231
 232         if (trig->set_trigger_state)
 233                 ret = trig->set_trigger_state(trig, true);
 234         if (ret) {
 235                 printk(KERN_ERR "set trigger state failed\n");
 236                 list_del(&pf->list);
 237         }
 238         return ret;
 239 }
 240 EXPORT_SYMBOL(iio_trigger_attach_poll_func);
 241
 242 int iio_trigger_dettach_poll_func(struct iio_trigger *trig,
 243                                   struct iio_poll_func *pf)
 244 {
 245         struct iio_poll_func *pf_cursor;
 246         unsigned long flags;
 247         int ret = -EINVAL;
 248
 249         spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
 250         list_for_each_entry(pf_cursor, &trig->pollfunc_list, list)
 251                 if (pf_cursor == pf) {
 252                         ret = 0;
 253                         break;
 254                 }
 255         if (!ret) {
 256                 if (list_is_singular(&trig->pollfunc_list)
 257                     && trig->set_trigger_state) {
 258                         spin_unlock_irqrestore(&trig->pollfunc_list_lock,
 259                                                flags);
 260                         /* May sleep hence cannot hold the spin lock */
 261                         ret = trig->set_trigger_state(trig, false);
 262                         if (ret)
 263                                 goto error_ret;
 264                         spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
 265                 }
 266                 /*
 267                  * Now we can delete safe in the knowledge that, if this is
 268                  * the last pollfunc then we have disabled the trigger anyway
 269                  * and so nothing should be able to call the pollfunc.
 270                  */
 271                 list_del(&pf_cursor->list);
 272         }
 273         spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
 274
 275 error_ret:
 276         return ret;
 277 }
 278 EXPORT_SYMBOL(iio_trigger_dettach_poll_func);
 279
 280 /**
 281  * iio_trigger_read_currrent() - trigger consumer sysfs query which trigger
 282  *
 283  * For trigger consumers the current_trigger interface allows the trigger
 284  * used by the device to be queried.
 285  **/
 286 static ssize_t iio_trigger_read_current(struct device *dev,
 287                                         struct device_attribute *attr,
 288                                         char *buf)
 289 {
 290         struct iio_dev *dev_info = dev_get_drvdata(dev);
 291         int len = 0;
 292         if (dev_info->trig)
 293                 len = sprintf(buf,
 294                               "%s\n",
 295                               dev_info->trig->name);
 296         return len;
 297 }
 298
 299 /**
 300  * iio_trigger_write_current() trigger consumer sysfs set current trigger
 301  *
 302  * For trigger consumers the current_trigger interface allows the trigger
 303  * used for this device to be specified at run time based on the triggers
 304  * name.
 305  **/
 306 static ssize_t iio_trigger_write_current(struct device *dev,
 307                                          struct device_attribute *attr,
 308                                          const char *buf,
 309                                          size_t len)
 310 {
 311         struct iio_dev *dev_info = dev_get_drvdata(dev);
 312         struct iio_trigger *oldtrig = dev_info->trig;
 313         mutex_lock(&dev_info->mlock);
 314         if (dev_info->currentmode == INDIO_RING_TRIGGERED) {
 315                 mutex_unlock(&dev_info->mlock);
 316                 return -EBUSY;
 317         }
 318         mutex_unlock(&dev_info->mlock);
 319
 320         dev_info->trig = iio_trigger_find_by_name(buf, len);
 321         if (oldtrig && dev_info->trig != oldtrig)
 322                 iio_put_trigger(oldtrig);
 323         if (dev_info->trig)
 324                 iio_get_trigger(dev_info->trig);
 325
 326         return len;
 327 }
 328
 329 static DEVICE_ATTR(current_trigger, S_IRUGO | S_IWUSR,
 330                    iio_trigger_read_current,
 331                    iio_trigger_write_current);
 332
 333 static struct attribute *iio_trigger_consumer_attrs[] = {
 334         &dev_attr_current_trigger.attr,
 335         NULL,
 336 };
 337
 338 static const struct attribute_group iio_trigger_consumer_attr_group = {
 339         .name = "trigger",
 340         .attrs = iio_trigger_consumer_attrs,
 341 };
 342
 343 static void iio_trig_release(struct device *device)
 344 {
 345         struct iio_trigger *trig = to_iio_trigger(device);
 346         kfree(trig);
 347         iio_put();
 348 }
 349
 350 static struct device_type iio_trig_type = {
 351         .release = iio_trig_release,
 352 };
 353
 354 struct iio_trigger *iio_allocate_trigger(void)
 355 {
 356         struct iio_trigger *trig;
 357         trig = kzalloc(sizeof *trig, GFP_KERNEL);
 358         if (trig) {
 359                 trig->dev.type = &iio_trig_type;
 360                 trig->dev.bus = &iio_bus_type;
 361                 device_initialize(&trig->dev);
 362                 dev_set_drvdata(&trig->dev, (void *)trig);
 363                 spin_lock_init(&trig->pollfunc_list_lock);
 364                 INIT_LIST_HEAD(&trig->list);
 365                 INIT_LIST_HEAD(&trig->pollfunc_list);
 366                 iio_get();
 367         }
 368         return trig;
 369 }
 370 EXPORT_SYMBOL(iio_allocate_trigger);
 371
 372 void iio_free_trigger(struct iio_trigger *trig)
 373 {
 374         if (trig)
 375                 put_device(&trig->dev);
 376 }
 377 EXPORT_SYMBOL(iio_free_trigger);
 378
 379 int iio_device_register_trigger_consumer(struct iio_dev *dev_info)
 380 {
 381         int ret;
 382         ret = sysfs_create_group(&dev_info->dev.kobj,
 383                                  &iio_trigger_consumer_attr_group);
 384         return ret;
 385 }
 386 EXPORT_SYMBOL(iio_device_register_trigger_consumer);
 387
 388 int iio_device_unregister_trigger_consumer(struct iio_dev *dev_info)
 389 {
 390         sysfs_remove_group(&dev_info->dev.kobj,
 391                            &iio_trigger_consumer_attr_group);
 392         return 0;
 393 }
 394 EXPORT_SYMBOL(iio_device_unregister_trigger_consumer);
 395
 396 int iio_alloc_pollfunc(struct iio_dev *indio_dev,
 397                        void (*immediate)(struct iio_dev *indio_dev),
 398                        void (*main)(struct iio_dev *private_data, s64 time))
 399 {
 400         indio_dev->pollfunc = kzalloc(sizeof(*indio_dev->pollfunc), GFP_KERNEL);
 401         if (indio_dev->pollfunc == NULL)
 402                 return -ENOMEM;
 403         indio_dev->pollfunc->poll_func_immediate = immediate;
 404         indio_dev->pollfunc->poll_func_main = main;
 405         indio_dev->pollfunc->private_data = indio_dev;
 406         return 0;
 407 }
 408 EXPORT_SYMBOL(iio_alloc_pollfunc);
 409
 410 int iio_triggered_ring_postenable(struct iio_dev *indio_dev)
 411 {
 412         return indio_dev->trig
 413                 ? iio_trigger_attach_poll_func(indio_dev->trig,
 414                                                indio_dev->pollfunc)
 415                 : 0;
 416 }
 417 EXPORT_SYMBOL(iio_triggered_ring_postenable);
 418
 419 int iio_triggered_ring_predisable(struct iio_dev *indio_dev)
 420 {
 421         return indio_dev->trig
 422                 ? iio_trigger_dettach_poll_func(indio_dev->trig,
 423                                                 indio_dev->pollfunc)
 424                 : 0;
 425 }
 426 EXPORT_SYMBOL(iio_triggered_ring_predisable);