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