linux/drivers/iio/industrialio-event.c
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   1/* Industrial I/O event handling
   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 * Based on elements of hwmon and input subsystems.
  10 */
  11
  12#include <linux/anon_inodes.h>
  13#include <linux/device.h>
  14#include <linux/fs.h>
  15#include <linux/kernel.h>
  16#include <linux/kfifo.h>
  17#include <linux/module.h>
  18#include <linux/poll.h>
  19#include <linux/sched.h>
  20#include <linux/slab.h>
  21#include <linux/uaccess.h>
  22#include <linux/wait.h>
  23#include <linux/iio/iio.h>
  24#include "iio_core.h"
  25#include <linux/iio/sysfs.h>
  26#include <linux/iio/events.h>
  27
  28/**
  29 * struct iio_event_interface - chrdev interface for an event line
  30 * @wait:               wait queue to allow blocking reads of events
  31 * @det_events:         list of detected events
  32 * @dev_attr_list:      list of event interface sysfs attribute
  33 * @flags:              file operations related flags including busy flag.
  34 * @group:              event interface sysfs attribute group
  35 */
  36struct iio_event_interface {
  37        wait_queue_head_t       wait;
  38        DECLARE_KFIFO(det_events, struct iio_event_data, 16);
  39
  40        struct list_head        dev_attr_list;
  41        unsigned long           flags;
  42        struct attribute_group  group;
  43};
  44
  45int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
  46{
  47        struct iio_event_interface *ev_int = indio_dev->event_interface;
  48        struct iio_event_data ev;
  49        int copied;
  50
  51        /* Does anyone care? */
  52        spin_lock(&ev_int->wait.lock);
  53        if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
  54
  55                ev.id = ev_code;
  56                ev.timestamp = timestamp;
  57
  58                copied = kfifo_put(&ev_int->det_events, &ev);
  59                if (copied != 0)
  60                        wake_up_locked_poll(&ev_int->wait, POLLIN);
  61        }
  62        spin_unlock(&ev_int->wait.lock);
  63
  64        return 0;
  65}
  66EXPORT_SYMBOL(iio_push_event);
  67
  68/**
  69 * iio_event_poll() - poll the event queue to find out if it has data
  70 */
  71static unsigned int iio_event_poll(struct file *filep,
  72                             struct poll_table_struct *wait)
  73{
  74        struct iio_event_interface *ev_int = filep->private_data;
  75        unsigned int events = 0;
  76
  77        poll_wait(filep, &ev_int->wait, wait);
  78
  79        spin_lock(&ev_int->wait.lock);
  80        if (!kfifo_is_empty(&ev_int->det_events))
  81                events = POLLIN | POLLRDNORM;
  82        spin_unlock(&ev_int->wait.lock);
  83
  84        return events;
  85}
  86
  87static ssize_t iio_event_chrdev_read(struct file *filep,
  88                                     char __user *buf,
  89                                     size_t count,
  90                                     loff_t *f_ps)
  91{
  92        struct iio_event_interface *ev_int = filep->private_data;
  93        unsigned int copied;
  94        int ret;
  95
  96        if (count < sizeof(struct iio_event_data))
  97                return -EINVAL;
  98
  99        spin_lock(&ev_int->wait.lock);
 100        if (kfifo_is_empty(&ev_int->det_events)) {
 101                if (filep->f_flags & O_NONBLOCK) {
 102                        ret = -EAGAIN;
 103                        goto error_unlock;
 104                }
 105                /* Blocking on device; waiting for something to be there */
 106                ret = wait_event_interruptible_locked(ev_int->wait,
 107                                        !kfifo_is_empty(&ev_int->det_events));
 108                if (ret)
 109                        goto error_unlock;
 110                /* Single access device so no one else can get the data */
 111        }
 112
 113        ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
 114
 115error_unlock:
 116        spin_unlock(&ev_int->wait.lock);
 117
 118        return ret ? ret : copied;
 119}
 120
 121static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
 122{
 123        struct iio_event_interface *ev_int = filep->private_data;
 124
 125        spin_lock(&ev_int->wait.lock);
 126        __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 127        /*
 128         * In order to maintain a clean state for reopening,
 129         * clear out any awaiting events. The mask will prevent
 130         * any new __iio_push_event calls running.
 131         */
 132        kfifo_reset_out(&ev_int->det_events);
 133        spin_unlock(&ev_int->wait.lock);
 134
 135        return 0;
 136}
 137
 138static const struct file_operations iio_event_chrdev_fileops = {
 139        .read =  iio_event_chrdev_read,
 140        .poll =  iio_event_poll,
 141        .release = iio_event_chrdev_release,
 142        .owner = THIS_MODULE,
 143        .llseek = noop_llseek,
 144};
 145
 146int iio_event_getfd(struct iio_dev *indio_dev)
 147{
 148        struct iio_event_interface *ev_int = indio_dev->event_interface;
 149        int fd;
 150
 151        if (ev_int == NULL)
 152                return -ENODEV;
 153
 154        spin_lock(&ev_int->wait.lock);
 155        if (__test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
 156                spin_unlock(&ev_int->wait.lock);
 157                return -EBUSY;
 158        }
 159        spin_unlock(&ev_int->wait.lock);
 160        fd = anon_inode_getfd("iio:event",
 161                                &iio_event_chrdev_fileops, ev_int, O_RDONLY);
 162        if (fd < 0) {
 163                spin_lock(&ev_int->wait.lock);
 164                __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
 165                spin_unlock(&ev_int->wait.lock);
 166        }
 167        return fd;
 168}
 169
 170static const char * const iio_ev_type_text[] = {
 171        [IIO_EV_TYPE_THRESH] = "thresh",
 172        [IIO_EV_TYPE_MAG] = "mag",
 173        [IIO_EV_TYPE_ROC] = "roc",
 174        [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
 175        [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 176};
 177
 178static const char * const iio_ev_dir_text[] = {
 179        [IIO_EV_DIR_EITHER] = "either",
 180        [IIO_EV_DIR_RISING] = "rising",
 181        [IIO_EV_DIR_FALLING] = "falling"
 182};
 183
 184static ssize_t iio_ev_state_store(struct device *dev,
 185                                  struct device_attribute *attr,
 186                                  const char *buf,
 187                                  size_t len)
 188{
 189        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 190        struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 191        int ret;
 192        bool val;
 193
 194        ret = strtobool(buf, &val);
 195        if (ret < 0)
 196                return ret;
 197
 198        ret = indio_dev->info->write_event_config(indio_dev,
 199                                                  this_attr->address,
 200                                                  val);
 201        return (ret < 0) ? ret : len;
 202}
 203
 204static ssize_t iio_ev_state_show(struct device *dev,
 205                                 struct device_attribute *attr,
 206                                 char *buf)
 207{
 208        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 209        struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 210        int val = indio_dev->info->read_event_config(indio_dev,
 211                                                     this_attr->address);
 212
 213        if (val < 0)
 214                return val;
 215        else
 216                return sprintf(buf, "%d\n", val);
 217}
 218
 219static ssize_t iio_ev_value_show(struct device *dev,
 220                                 struct device_attribute *attr,
 221                                 char *buf)
 222{
 223        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 224        struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 225        int val, ret;
 226
 227        ret = indio_dev->info->read_event_value(indio_dev,
 228                                                this_attr->address, &val);
 229        if (ret < 0)
 230                return ret;
 231
 232        return sprintf(buf, "%d\n", val);
 233}
 234
 235static ssize_t iio_ev_value_store(struct device *dev,
 236                                  struct device_attribute *attr,
 237                                  const char *buf,
 238                                  size_t len)
 239{
 240        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 241        struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 242        unsigned long val;
 243        int ret;
 244
 245        if (!indio_dev->info->write_event_value)
 246                return -EINVAL;
 247
 248        ret = strict_strtoul(buf, 10, &val);
 249        if (ret)
 250                return ret;
 251
 252        ret = indio_dev->info->write_event_value(indio_dev, this_attr->address,
 253                                                 val);
 254        if (ret < 0)
 255                return ret;
 256
 257        return len;
 258}
 259
 260static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
 261                                      struct iio_chan_spec const *chan)
 262{
 263        int ret = 0, i, attrcount = 0;
 264        u64 mask = 0;
 265        char *postfix;
 266        if (!chan->event_mask)
 267                return 0;
 268
 269        for_each_set_bit(i, &chan->event_mask, sizeof(chan->event_mask)*8) {
 270                postfix = kasprintf(GFP_KERNEL, "%s_%s_en",
 271                                    iio_ev_type_text[i/IIO_EV_DIR_MAX],
 272                                    iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
 273                if (postfix == NULL) {
 274                        ret = -ENOMEM;
 275                        goto error_ret;
 276                }
 277                if (chan->modified)
 278                        mask = IIO_MOD_EVENT_CODE(chan->type, 0, chan->channel,
 279                                                  i/IIO_EV_DIR_MAX,
 280                                                  i%IIO_EV_DIR_MAX);
 281                else if (chan->differential)
 282                        mask = IIO_EVENT_CODE(chan->type,
 283                                              0, 0,
 284                                              i%IIO_EV_DIR_MAX,
 285                                              i/IIO_EV_DIR_MAX,
 286                                              0,
 287                                              chan->channel,
 288                                              chan->channel2);
 289                else
 290                        mask = IIO_UNMOD_EVENT_CODE(chan->type,
 291                                                    chan->channel,
 292                                                    i/IIO_EV_DIR_MAX,
 293                                                    i%IIO_EV_DIR_MAX);
 294
 295                ret = __iio_add_chan_devattr(postfix,
 296                                             chan,
 297                                             &iio_ev_state_show,
 298                                             iio_ev_state_store,
 299                                             mask,
 300                                             0,
 301                                             &indio_dev->dev,
 302                                             &indio_dev->event_interface->
 303                                             dev_attr_list);
 304                kfree(postfix);
 305                if (ret)
 306                        goto error_ret;
 307                attrcount++;
 308                postfix = kasprintf(GFP_KERNEL, "%s_%s_value",
 309                                    iio_ev_type_text[i/IIO_EV_DIR_MAX],
 310                                    iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
 311                if (postfix == NULL) {
 312                        ret = -ENOMEM;
 313                        goto error_ret;
 314                }
 315                ret = __iio_add_chan_devattr(postfix, chan,
 316                                             iio_ev_value_show,
 317                                             iio_ev_value_store,
 318                                             mask,
 319                                             0,
 320                                             &indio_dev->dev,
 321                                             &indio_dev->event_interface->
 322                                             dev_attr_list);
 323                kfree(postfix);
 324                if (ret)
 325                        goto error_ret;
 326                attrcount++;
 327        }
 328        ret = attrcount;
 329error_ret:
 330        return ret;
 331}
 332
 333static inline void __iio_remove_event_config_attrs(struct iio_dev *indio_dev)
 334{
 335        struct iio_dev_attr *p, *n;
 336        list_for_each_entry_safe(p, n,
 337                                 &indio_dev->event_interface->
 338                                 dev_attr_list, l) {
 339                kfree(p->dev_attr.attr.name);
 340                kfree(p);
 341        }
 342}
 343
 344static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
 345{
 346        int j, ret, attrcount = 0;
 347
 348        /* Dynically created from the channels array */
 349        for (j = 0; j < indio_dev->num_channels; j++) {
 350                ret = iio_device_add_event_sysfs(indio_dev,
 351                                                 &indio_dev->channels[j]);
 352                if (ret < 0)
 353                        goto error_clear_attrs;
 354                attrcount += ret;
 355        }
 356        return attrcount;
 357
 358error_clear_attrs:
 359        __iio_remove_event_config_attrs(indio_dev);
 360
 361        return ret;
 362}
 363
 364static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
 365{
 366        int j;
 367
 368        for (j = 0; j < indio_dev->num_channels; j++)
 369                if (indio_dev->channels[j].event_mask != 0)
 370                        return true;
 371        return false;
 372}
 373
 374static void iio_setup_ev_int(struct iio_event_interface *ev_int)
 375{
 376        INIT_KFIFO(ev_int->det_events);
 377        init_waitqueue_head(&ev_int->wait);
 378}
 379
 380static const char *iio_event_group_name = "events";
 381int iio_device_register_eventset(struct iio_dev *indio_dev)
 382{
 383        struct iio_dev_attr *p;
 384        int ret = 0, attrcount_orig = 0, attrcount, attrn;
 385        struct attribute **attr;
 386
 387        if (!(indio_dev->info->event_attrs ||
 388              iio_check_for_dynamic_events(indio_dev)))
 389                return 0;
 390
 391        indio_dev->event_interface =
 392                kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
 393        if (indio_dev->event_interface == NULL) {
 394                ret = -ENOMEM;
 395                goto error_ret;
 396        }
 397
 398        INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
 399
 400        iio_setup_ev_int(indio_dev->event_interface);
 401        if (indio_dev->info->event_attrs != NULL) {
 402                attr = indio_dev->info->event_attrs->attrs;
 403                while (*attr++ != NULL)
 404                        attrcount_orig++;
 405        }
 406        attrcount = attrcount_orig;
 407        if (indio_dev->channels) {
 408                ret = __iio_add_event_config_attrs(indio_dev);
 409                if (ret < 0)
 410                        goto error_free_setup_event_lines;
 411                attrcount += ret;
 412        }
 413
 414        indio_dev->event_interface->group.name = iio_event_group_name;
 415        indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
 416                                                          sizeof(indio_dev->event_interface->group.attrs[0]),
 417                                                          GFP_KERNEL);
 418        if (indio_dev->event_interface->group.attrs == NULL) {
 419                ret = -ENOMEM;
 420                goto error_free_setup_event_lines;
 421        }
 422        if (indio_dev->info->event_attrs)
 423                memcpy(indio_dev->event_interface->group.attrs,
 424                       indio_dev->info->event_attrs->attrs,
 425                       sizeof(indio_dev->event_interface->group.attrs[0])
 426                       *attrcount_orig);
 427        attrn = attrcount_orig;
 428        /* Add all elements from the list. */
 429        list_for_each_entry(p,
 430                            &indio_dev->event_interface->dev_attr_list,
 431                            l)
 432                indio_dev->event_interface->group.attrs[attrn++] =
 433                        &p->dev_attr.attr;
 434        indio_dev->groups[indio_dev->groupcounter++] =
 435                &indio_dev->event_interface->group;
 436
 437        return 0;
 438
 439error_free_setup_event_lines:
 440        __iio_remove_event_config_attrs(indio_dev);
 441        kfree(indio_dev->event_interface);
 442error_ret:
 443
 444        return ret;
 445}
 446
 447void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 448{
 449        if (indio_dev->event_interface == NULL)
 450                return;
 451        __iio_remove_event_config_attrs(indio_dev);
 452        kfree(indio_dev->event_interface->group.attrs);
 453        kfree(indio_dev->event_interface);
 454}
 455
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