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
  22 /* RFC - Question of approach
  23  * Make the common case (single sensor single trigger)
  24  * simple by starting trigger capture from when first sensors
  25  * is added.
  26  *
  27  * Complex simultaneous start requires use of 'hold' functionality
  28  * of the trigger. (not implemented)
  29  *
  30  * Any other suggestions?
  31  */
  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 struct iio_trigger *iio_trigger_find_by_name(const char *name, size_t len)
 155 {
 156         struct iio_trigger *trig;
 157         bool found = false;
 158
 159         mutex_lock(&iio_trigger_list_lock);
 160         list_for_each_entry(trig, &iio_trigger_list, list) {
 161                 if (strncmp(trig->name, name, len) == 0) {
 162                         found = true;
 163                         break;
 164                 }
 165         }
 166         mutex_unlock(&iio_trigger_list_lock);
 167
 168         return found ? trig : NULL;
 169 };
 170 EXPORT_SYMBOL(iio_trigger_find_by_name);
 171
 172 void iio_trigger_poll(struct iio_trigger *trig)
 173 {
 174         struct iio_poll_func *pf_cursor;
 175
 176         list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
 177                 if (pf_cursor->poll_func_immediate) {
 178                         pf_cursor->poll_func_immediate(pf_cursor->private_data);
 179                         trig->use_count++;
 180                 }
 181         }
 182         list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
 183                 if (pf_cursor->poll_func_main) {
 184                         pf_cursor->poll_func_main(pf_cursor->private_data);
 185                         trig->use_count++;
 186                 }
 187         }
 188 }
 189 EXPORT_SYMBOL(iio_trigger_poll);
 190
 191 void iio_trigger_notify_done(struct iio_trigger *trig)
 192 {
 193         trig->use_count--;
 194         if (trig->use_count == 0 && trig->try_reenable)
 195                 if (trig->try_reenable(trig)) {
 196                         /* Missed and interrupt so launch new poll now */
 197                         trig->timestamp = 0;
 198                         iio_trigger_poll(trig);
 199                 }
 200 }
 201 EXPORT_SYMBOL(iio_trigger_notify_done);
 202
 203 /**
 204  * iio_trigger_read_name() - retrieve useful identifying name
 205  **/
 206 ssize_t iio_trigger_read_name(struct device *dev,
 207                               struct device_attribute *attr,
 208                               char *buf)
 209 {
 210         struct iio_trigger *trig = dev_get_drvdata(dev);
 211         return sprintf(buf, "%s\n", trig->name);
 212 }
 213 EXPORT_SYMBOL(iio_trigger_read_name);
 214
 215 /* Trigger Consumer related functions */
 216
 217 /* Complexity in here.  With certain triggers (datardy) an acknowledgement
 218  * may be needed if the pollfuncs do not include the data read for the
 219  * triggering device.
 220  * This is not currently handled.  Alternative of not enabling trigger unless
 221  * the relevant function is in there may be the best option.
 222  */
 223 /* Worth protecting against double additions?*/
 224 int iio_trigger_attach_poll_func(struct iio_trigger *trig,
 225                                  struct iio_poll_func *pf)
 226 {
 227         int ret = 0;
 228         unsigned long flags;
 229
 230         spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
 231         list_add_tail(&pf->list, &trig->pollfunc_list);
 232         spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
 233
 234         if (trig->set_trigger_state)
 235                 ret = trig->set_trigger_state(trig, true);
 236         if (ret) {
 237                 printk(KERN_ERR "set trigger state failed\n");
 238                 list_del(&pf->list);
 239         }
 240         return ret;
 241 }
 242 EXPORT_SYMBOL(iio_trigger_attach_poll_func);
 243
 244 int iio_trigger_dettach_poll_func(struct iio_trigger *trig,
 245                                   struct iio_poll_func *pf)
 246 {
 247         struct iio_poll_func *pf_cursor;
 248         unsigned long flags;
 249         int ret = -EINVAL;
 250
 251         spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
 252         list_for_each_entry(pf_cursor, &trig->pollfunc_list, list)
 253                 if (pf_cursor == pf) {
 254                         ret = 0;
 255                         break;
 256                 }
 257         if (!ret) {
 258                 if (list_is_singular(&trig->pollfunc_list)
 259                     && trig->set_trigger_state) {
 260                         spin_unlock_irqrestore(&trig->pollfunc_list_lock,
 261                                                flags);
 262                         /* May sleep hence cannot hold the spin lock */
 263                         ret = trig->set_trigger_state(trig, false);
 264                         if (ret)
 265                                 goto error_ret;
 266                         spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
 267                 }
 268                 /*
 269                  * Now we can delete safe in the knowledge that, if this is
 270                  * the last pollfunc then we have disabled the trigger anyway
 271                  * and so nothing should be able to call the pollfunc.
 272                  */
 273                 list_del(&pf_cursor->list);
 274         }
 275         spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
 276
 277 error_ret:
 278         return ret;
 279 }
 280 EXPORT_SYMBOL(iio_trigger_dettach_poll_func);
 281
 282 /**
 283  * iio_trigger_read_currrent() trigger consumer sysfs query which trigger
 284  *
 285  * For trigger consumers the current_trigger interface allows the trigger
 286  * used by the device to be queried.
 287  **/
 288 static ssize_t iio_trigger_read_current(struct device *dev,
 289                                         struct device_attribute *attr,
 290                                         char *buf)
 291 {
 292         struct iio_dev *dev_info = dev_get_drvdata(dev);
 293         int len = 0;
 294         if (dev_info->trig)
 295                 len = snprintf(buf,
 296                                IIO_TRIGGER_NAME_LENGTH,
 297                                "%s\n",
 298                                dev_info->trig->name);
 299         return len;
 300 }
 301
 302 /**
 303  * iio_trigger_write_current() trigger consumer sysfs set current trigger
 304  *
 305  * For trigger consumers the current_trigger interface allows the trigger
 306  * used for this device to be specified at run time based on the triggers
 307  * name.
 308  **/
 309 static ssize_t iio_trigger_write_current(struct device *dev,
 310                                          struct device_attribute *attr,
 311                                          const char *buf,
 312                                          size_t len)
 313 {
 314         struct iio_dev *dev_info = dev_get_drvdata(dev);
 315         struct iio_trigger *oldtrig = dev_info->trig;
 316         mutex_lock(&dev_info->mlock);
 317         if (dev_info->currentmode == INDIO_RING_TRIGGERED) {
 318                 mutex_unlock(&dev_info->mlock);
 319                 return -EBUSY;
 320         }
 321         mutex_unlock(&dev_info->mlock);
 322
 323         len = len < IIO_TRIGGER_NAME_LENGTH ? len : IIO_TRIGGER_NAME_LENGTH;
 324
 325         dev_info->trig = iio_trigger_find_by_name(buf, len);
 326         if (oldtrig && dev_info->trig != oldtrig)
 327                 iio_put_trigger(oldtrig);
 328         if (dev_info->trig)
 329                 iio_get_trigger(dev_info->trig);
 330
 331         return len;
 332 }
 333
 334 DEVICE_ATTR(current_trigger, S_IRUGO | S_IWUSR,
 335             iio_trigger_read_current,
 336             iio_trigger_write_current);
 337
 338 static struct attribute *iio_trigger_consumer_attrs[] = {
 339         &dev_attr_current_trigger.attr,
 340         NULL,
 341 };
 342
 343 static const struct attribute_group iio_trigger_consumer_attr_group = {
 344         .name = "trigger",
 345         .attrs = iio_trigger_consumer_attrs,
 346 };
 347
 348 static void iio_trig_release(struct device *device)
 349 {
 350         struct iio_trigger *trig = to_iio_trigger(device);
 351         kfree(trig);
 352         iio_put();
 353 }
 354
 355 static struct device_type iio_trig_type = {
 356         .release = iio_trig_release,
 357 };
 358
 359 struct iio_trigger *iio_allocate_trigger(void)
 360 {
 361         struct iio_trigger *trig;
 362         trig = kzalloc(sizeof *trig, GFP_KERNEL);
 363         if (trig) {
 364                 trig->dev.type = &iio_trig_type;
 365                 trig->dev.class = &iio_class;
 366                 device_initialize(&trig->dev);
 367                 dev_set_drvdata(&trig->dev, (void *)trig);
 368                 spin_lock_init(&trig->pollfunc_list_lock);
 369                 INIT_LIST_HEAD(&trig->list);
 370                 INIT_LIST_HEAD(&trig->pollfunc_list);
 371                 iio_get();
 372         }
 373         return trig;
 374 }
 375 EXPORT_SYMBOL(iio_allocate_trigger);
 376
 377 void iio_free_trigger(struct iio_trigger *trig)
 378 {
 379         if (trig)
 380                 put_device(&trig->dev);
 381 }
 382 EXPORT_SYMBOL(iio_free_trigger);
 383
 384 int iio_device_register_trigger_consumer(struct iio_dev *dev_info)
 385 {
 386         int ret;
 387         ret = sysfs_create_group(&dev_info->dev.kobj,
 388                                  &iio_trigger_consumer_attr_group);
 389         return ret;
 390 }
 391 EXPORT_SYMBOL(iio_device_register_trigger_consumer);
 392
 393 int iio_device_unregister_trigger_consumer(struct iio_dev *dev_info)
 394 {
 395         sysfs_remove_group(&dev_info->dev.kobj,
 396                            &iio_trigger_consumer_attr_group);
 397         return 0;
 398 }
 399 EXPORT_SYMBOL(iio_device_unregister_trigger_consumer);
 400