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