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 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         if (len && name[len - 1] == '\n')
 160                 len--;
 161
 162         mutex_lock(&iio_trigger_list_lock);
 163         list_for_each_entry(trig, &iio_trigger_list, list) {
 164                 if (strncmp(trig->name, name, len) == 0) {
 165                         found = true;
 166                         break;
 167                 }
 168         }
 169         mutex_unlock(&iio_trigger_list_lock);
 170
 171         return found ? trig : NULL;
 172 }
 173 EXPORT_SYMBOL(iio_trigger_find_by_name);
 174
 175 void iio_trigger_poll(struct iio_trigger *trig)
 176 {
 177         struct iio_poll_func *pf_cursor;
 178
 179         list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
 180                 if (pf_cursor->poll_func_immediate) {
 181                         pf_cursor->poll_func_immediate(pf_cursor->private_data);
 182                         trig->use_count++;
 183                 }
 184         }
 185         list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
 186                 if (pf_cursor->poll_func_main) {
 187                         pf_cursor->poll_func_main(pf_cursor->private_data);
 188                         trig->use_count++;
 189                 }
 190         }
 191 }
 192 EXPORT_SYMBOL(iio_trigger_poll);
 193
 194 void iio_trigger_notify_done(struct iio_trigger *trig)
 195 {
 196         trig->use_count--;
 197         if (trig->use_count == 0 && trig->try_reenable)
 198                 if (trig->try_reenable(trig)) {
 199                         /* Missed and interrupt so launch new poll now */
 200                         trig->timestamp = 0;
 201                         iio_trigger_poll(trig);
 202                 }
 203 }
 204 EXPORT_SYMBOL(iio_trigger_notify_done);
 205
 206 /**
 207  * iio_trigger_read_name() - retrieve useful identifying name
 208  **/
 209 ssize_t iio_trigger_read_name(struct device *dev,
 210                               struct device_attribute *attr,
 211                               char *buf)
 212 {
 213         struct iio_trigger *trig = dev_get_drvdata(dev);
 214         return sprintf(buf, "%s\n", trig->name);
 215 }
 216 EXPORT_SYMBOL(iio_trigger_read_name);
 217
 218 /* Trigger Consumer related functions */
 219
 220 /* Complexity in here.  With certain triggers (datardy) an acknowledgement
 221  * may be needed if the pollfuncs do not include the data read for the
 222  * triggering device.
 223  * This is not currently handled.  Alternative of not enabling trigger unless
 224  * the relevant function is in there may be the best option.
 225  */
 226 /* Worth protecting against double additions?*/
 227 int iio_trigger_attach_poll_func(struct iio_trigger *trig,
 228                                  struct iio_poll_func *pf)
 229 {
 230         int ret = 0;
 231         unsigned long flags;
 232
 233         spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
 234         list_add_tail(&pf->list, &trig->pollfunc_list);
 235         spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
 236
 237         if (trig->set_trigger_state)
 238                 ret = trig->set_trigger_state(trig, true);
 239         if (ret) {
 240                 printk(KERN_ERR "set trigger state failed\n");
 241                 list_del(&pf->list);
 242         }
 243         return ret;
 244 }
 245 EXPORT_SYMBOL(iio_trigger_attach_poll_func);
 246
 247 int iio_trigger_dettach_poll_func(struct iio_trigger *trig,
 248                                   struct iio_poll_func *pf)
 249 {
 250         struct iio_poll_func *pf_cursor;
 251         unsigned long flags;
 252         int ret = -EINVAL;
 253
 254         spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
 255         list_for_each_entry(pf_cursor, &trig->pollfunc_list, list)
 256                 if (pf_cursor == pf) {
 257                         ret = 0;
 258                         break;
 259                 }
 260         if (!ret) {
 261                 if (list_is_singular(&trig->pollfunc_list)
 262                     && trig->set_trigger_state) {
 263                         spin_unlock_irqrestore(&trig->pollfunc_list_lock,
 264                                                flags);
 265                         /* May sleep hence cannot hold the spin lock */
 266                         ret = trig->set_trigger_state(trig, false);
 267                         if (ret)
 268                                 goto error_ret;
 269                         spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
 270                 }
 271                 /*
 272                  * Now we can delete safe in the knowledge that, if this is
 273                  * the last pollfunc then we have disabled the trigger anyway
 274                  * and so nothing should be able to call the pollfunc.
 275                  */
 276                 list_del(&pf_cursor->list);
 277         }
 278         spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);
 279
 280 error_ret:
 281         return ret;
 282 }
 283 EXPORT_SYMBOL(iio_trigger_dettach_poll_func);
 284
 285 /**
 286  * iio_trigger_read_currrent() - trigger consumer sysfs query which trigger
 287  *
 288  * For trigger consumers the current_trigger interface allows the trigger
 289  * used by the device to be queried.
 290  **/
 291 static ssize_t iio_trigger_read_current(struct device *dev,
 292                                         struct device_attribute *attr,
 293                                         char *buf)
 294 {
 295         struct iio_dev *dev_info = dev_get_drvdata(dev);
 296         int len = 0;
 297         if (dev_info->trig)
 298                 len = snprintf(buf,
 299                                IIO_TRIGGER_NAME_LENGTH,
 300                                "%s\n",
 301                                dev_info->trig->name);
 302         return len;
 303 }
 304
 305 /**
 306  * iio_trigger_write_current() trigger consumer sysfs set current trigger
 307  *
 308  * For trigger consumers the current_trigger interface allows the trigger
 309  * used for this device to be specified at run time based on the triggers
 310  * name.
 311  **/
 312 static ssize_t iio_trigger_write_current(struct device *dev,
 313                                          struct device_attribute *attr,
 314                                          const char *buf,
 315                                          size_t len)
 316 {
 317         struct iio_dev *dev_info = dev_get_drvdata(dev);
 318         struct iio_trigger *oldtrig = dev_info->trig;
 319         mutex_lock(&dev_info->mlock);
 320         if (dev_info->currentmode == INDIO_RING_TRIGGERED) {
 321                 mutex_unlock(&dev_info->mlock);
 322                 return -EBUSY;
 323         }
 324         mutex_unlock(&dev_info->mlock);
 325
 326         len = len < IIO_TRIGGER_NAME_LENGTH ? len : IIO_TRIGGER_NAME_LENGTH;
 327
 328         dev_info->trig = iio_trigger_find_by_name(buf, len);
 329         if (oldtrig && dev_info->trig != oldtrig)
 330                 iio_put_trigger(oldtrig);
 331         if (dev_info->trig)
 332                 iio_get_trigger(dev_info->trig);
 333
 334         return len;
 335 }
 336
 337 static DEVICE_ATTR(current_trigger, S_IRUGO | S_IWUSR,
 338                    iio_trigger_read_current,
 339                    iio_trigger_write_current);
 340
 341 static struct attribute *iio_trigger_consumer_attrs[] = {
 342         &dev_attr_current_trigger.attr,
 343         NULL,
 344 };
 345
 346 static const struct attribute_group iio_trigger_consumer_attr_group = {
 347         .name = "trigger",
 348         .attrs = iio_trigger_consumer_attrs,
 349 };
 350
 351 static void iio_trig_release(struct device *device)
 352 {
 353         struct iio_trigger *trig = to_iio_trigger(device);
 354         kfree(trig);
 355         iio_put();
 356 }
 357
 358 static struct device_type iio_trig_type = {
 359         .release = iio_trig_release,
 360 };
 361
 362 struct iio_trigger *iio_allocate_trigger(void)
 363 {
 364         struct iio_trigger *trig;
 365         trig = kzalloc(sizeof *trig, GFP_KERNEL);
 366         if (trig) {
 367                 trig->dev.type = &iio_trig_type;
 368                 trig->dev.bus = &iio_bus_type;
 369                 device_initialize(&trig->dev);
 370                 dev_set_drvdata(&trig->dev, (void *)trig);
 371                 spin_lock_init(&trig->pollfunc_list_lock);
 372                 INIT_LIST_HEAD(&trig->list);
 373                 INIT_LIST_HEAD(&trig->pollfunc_list);
 374                 iio_get();
 375         }
 376         return trig;
 377 }
 378 EXPORT_SYMBOL(iio_allocate_trigger);
 379
 380 void iio_free_trigger(struct iio_trigger *trig)
 381 {
 382         if (trig)
 383                 put_device(&trig->dev);
 384 }
 385 EXPORT_SYMBOL(iio_free_trigger);
 386
 387 int iio_device_register_trigger_consumer(struct iio_dev *dev_info)
 388 {
 389         int ret;
 390         ret = sysfs_create_group(&dev_info->dev.kobj,
 391                                  &iio_trigger_consumer_attr_group);
 392         return ret;
 393 }
 394 EXPORT_SYMBOL(iio_device_register_trigger_consumer);
 395
 396 int iio_device_unregister_trigger_consumer(struct iio_dev *dev_info)
 397 {
 398         sysfs_remove_group(&dev_info->dev.kobj,
 399                            &iio_trigger_consumer_attr_group);
 400         return 0;
 401 }
 402 EXPORT_SYMBOL(iio_device_unregister_trigger_consumer);
 403