1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Industrial I/O event handling 3 * 4 * Copyright (c) 2008 Jonathan Cameron 5 * 6 * Based on elements of hwmon and input subsystems. 7 */ 8 9 #include <linux/anon_inodes.h> 10 #include <linux/device.h> 11 #include <linux/fs.h> 12 #include <linux/kernel.h> 13 #include <linux/kfifo.h> 14 #include <linux/module.h> 15 #include <linux/poll.h> 16 #include <linux/sched.h> 17 #include <linux/slab.h> 18 #include <linux/uaccess.h> 19 #include <linux/wait.h> 20 #include <linux/iio/iio.h> 21 #include "iio_core.h" 22 #include <linux/iio/sysfs.h> 23 #include <linux/iio/events.h> 24 25 /** 26 * struct iio_event_interface - chrdev interface for an event line 27 * @wait: wait queue to allow blocking reads of events 28 * @det_events: list of detected events 29 * @dev_attr_list: list of event interface sysfs attribute 30 * @flags: file operations related flags including busy flag. 31 * @group: event interface sysfs attribute group 32 * @read_lock: lock to protect kfifo read operations 33 */ 34 struct iio_event_interface { 35 wait_queue_head_t wait; 36 DECLARE_KFIFO(det_events, struct iio_event_data, 16); 37 38 struct list_head dev_attr_list; 39 unsigned long flags; 40 struct attribute_group group; 41 struct mutex read_lock; 42 }; 43 44 bool iio_event_enabled(const struct iio_event_interface *ev_int) 45 { 46 return !!test_bit(IIO_BUSY_BIT_POS, &ev_int->flags); 47 } 48 49 /** 50 * iio_push_event() - try to add event to the list for userspace reading 51 * @indio_dev: IIO device structure 52 * @ev_code: What event 53 * @timestamp: When the event occurred 54 * 55 * Note: The caller must make sure that this function is not running 56 * concurrently for the same indio_dev more than once. 57 * 58 * This function may be safely used as soon as a valid reference to iio_dev has 59 * been obtained via iio_device_alloc(), but any events that are submitted 60 * before iio_device_register() has successfully completed will be silently 61 * discarded. 62 **/ 63 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp) 64 { 65 struct iio_event_interface *ev_int = indio_dev->event_interface; 66 struct iio_event_data ev; 67 int copied; 68 69 if (!ev_int) 70 return 0; 71 72 /* Does anyone care? */ 73 if (iio_event_enabled(ev_int)) { 74 75 ev.id = ev_code; 76 ev.timestamp = timestamp; 77 78 copied = kfifo_put(&ev_int->det_events, ev); 79 if (copied != 0) 80 wake_up_poll(&ev_int->wait, EPOLLIN); 81 } 82 83 return 0; 84 } 85 EXPORT_SYMBOL(iio_push_event); 86 87 /** 88 * iio_event_poll() - poll the event queue to find out if it has data 89 * @filep: File structure pointer to identify the device 90 * @wait: Poll table pointer to add the wait queue on 91 * 92 * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading 93 * or a negative error code on failure 94 */ 95 static __poll_t iio_event_poll(struct file *filep, 96 struct poll_table_struct *wait) 97 { 98 struct iio_dev *indio_dev = filep->private_data; 99 struct iio_event_interface *ev_int = indio_dev->event_interface; 100 __poll_t events = 0; 101 102 if (!indio_dev->info) 103 return events; 104 105 poll_wait(filep, &ev_int->wait, wait); 106 107 if (!kfifo_is_empty(&ev_int->det_events)) 108 events = EPOLLIN | EPOLLRDNORM; 109 110 return events; 111 } 112 113 static ssize_t iio_event_chrdev_read(struct file *filep, 114 char __user *buf, 115 size_t count, 116 loff_t *f_ps) 117 { 118 struct iio_dev *indio_dev = filep->private_data; 119 struct iio_event_interface *ev_int = indio_dev->event_interface; 120 unsigned int copied; 121 int ret; 122 123 if (!indio_dev->info) 124 return -ENODEV; 125 126 if (count < sizeof(struct iio_event_data)) 127 return -EINVAL; 128 129 do { 130 if (kfifo_is_empty(&ev_int->det_events)) { 131 if (filep->f_flags & O_NONBLOCK) 132 return -EAGAIN; 133 134 ret = wait_event_interruptible(ev_int->wait, 135 !kfifo_is_empty(&ev_int->det_events) || 136 indio_dev->info == NULL); 137 if (ret) 138 return ret; 139 if (indio_dev->info == NULL) 140 return -ENODEV; 141 } 142 143 if (mutex_lock_interruptible(&ev_int->read_lock)) 144 return -ERESTARTSYS; 145 ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied); 146 mutex_unlock(&ev_int->read_lock); 147 148 if (ret) 149 return ret; 150 151 /* 152 * If we couldn't read anything from the fifo (a different 153 * thread might have been faster) we either return -EAGAIN if 154 * the file descriptor is non-blocking, otherwise we go back to 155 * sleep and wait for more data to arrive. 156 */ 157 if (copied == 0 && (filep->f_flags & O_NONBLOCK)) 158 return -EAGAIN; 159 160 } while (copied == 0); 161 162 return copied; 163 } 164 165 static int iio_event_chrdev_release(struct inode *inode, struct file *filep) 166 { 167 struct iio_dev *indio_dev = filep->private_data; 168 struct iio_event_interface *ev_int = indio_dev->event_interface; 169 170 clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags); 171 172 iio_device_put(indio_dev); 173 174 return 0; 175 } 176 177 static const struct file_operations iio_event_chrdev_fileops = { 178 .read = iio_event_chrdev_read, 179 .poll = iio_event_poll, 180 .release = iio_event_chrdev_release, 181 .owner = THIS_MODULE, 182 .llseek = noop_llseek, 183 }; 184 185 int iio_event_getfd(struct iio_dev *indio_dev) 186 { 187 struct iio_event_interface *ev_int = indio_dev->event_interface; 188 int fd; 189 190 if (ev_int == NULL) 191 return -ENODEV; 192 193 fd = mutex_lock_interruptible(&indio_dev->mlock); 194 if (fd) 195 return fd; 196 197 if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) { 198 fd = -EBUSY; 199 goto unlock; 200 } 201 202 iio_device_get(indio_dev); 203 204 fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops, 205 indio_dev, O_RDONLY | O_CLOEXEC); 206 if (fd < 0) { 207 clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags); 208 iio_device_put(indio_dev); 209 } else { 210 kfifo_reset_out(&ev_int->det_events); 211 } 212 213 unlock: 214 mutex_unlock(&indio_dev->mlock); 215 return fd; 216 } 217 218 static const char * const iio_ev_type_text[] = { 219 [IIO_EV_TYPE_THRESH] = "thresh", 220 [IIO_EV_TYPE_MAG] = "mag", 221 [IIO_EV_TYPE_ROC] = "roc", 222 [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive", 223 [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive", 224 [IIO_EV_TYPE_CHANGE] = "change", 225 }; 226 227 static const char * const iio_ev_dir_text[] = { 228 [IIO_EV_DIR_EITHER] = "either", 229 [IIO_EV_DIR_RISING] = "rising", 230 [IIO_EV_DIR_FALLING] = "falling" 231 }; 232 233 static const char * const iio_ev_info_text[] = { 234 [IIO_EV_INFO_ENABLE] = "en", 235 [IIO_EV_INFO_VALUE] = "value", 236 [IIO_EV_INFO_HYSTERESIS] = "hysteresis", 237 [IIO_EV_INFO_PERIOD] = "period", 238 [IIO_EV_INFO_HIGH_PASS_FILTER_3DB] = "high_pass_filter_3db", 239 [IIO_EV_INFO_LOW_PASS_FILTER_3DB] = "low_pass_filter_3db", 240 }; 241 242 static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr) 243 { 244 return attr->c->event_spec[attr->address & 0xffff].dir; 245 } 246 247 static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr) 248 { 249 return attr->c->event_spec[attr->address & 0xffff].type; 250 } 251 252 static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr) 253 { 254 return (attr->address >> 16) & 0xffff; 255 } 256 257 static ssize_t iio_ev_state_store(struct device *dev, 258 struct device_attribute *attr, 259 const char *buf, 260 size_t len) 261 { 262 struct iio_dev *indio_dev = dev_to_iio_dev(dev); 263 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr); 264 int ret; 265 bool val; 266 267 ret = strtobool(buf, &val); 268 if (ret < 0) 269 return ret; 270 271 ret = indio_dev->info->write_event_config(indio_dev, 272 this_attr->c, iio_ev_attr_type(this_attr), 273 iio_ev_attr_dir(this_attr), val); 274 275 return (ret < 0) ? ret : len; 276 } 277 278 static ssize_t iio_ev_state_show(struct device *dev, 279 struct device_attribute *attr, 280 char *buf) 281 { 282 struct iio_dev *indio_dev = dev_to_iio_dev(dev); 283 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr); 284 int val; 285 286 val = indio_dev->info->read_event_config(indio_dev, 287 this_attr->c, iio_ev_attr_type(this_attr), 288 iio_ev_attr_dir(this_attr)); 289 if (val < 0) 290 return val; 291 else 292 return sprintf(buf, "%d\n", val); 293 } 294 295 static ssize_t iio_ev_value_show(struct device *dev, 296 struct device_attribute *attr, 297 char *buf) 298 { 299 struct iio_dev *indio_dev = dev_to_iio_dev(dev); 300 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr); 301 int val, val2, val_arr[2]; 302 int ret; 303 304 ret = indio_dev->info->read_event_value(indio_dev, 305 this_attr->c, iio_ev_attr_type(this_attr), 306 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr), 307 &val, &val2); 308 if (ret < 0) 309 return ret; 310 val_arr[0] = val; 311 val_arr[1] = val2; 312 return iio_format_value(buf, ret, 2, val_arr); 313 } 314 315 static ssize_t iio_ev_value_store(struct device *dev, 316 struct device_attribute *attr, 317 const char *buf, 318 size_t len) 319 { 320 struct iio_dev *indio_dev = dev_to_iio_dev(dev); 321 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr); 322 int val, val2; 323 int ret; 324 325 if (!indio_dev->info->write_event_value) 326 return -EINVAL; 327 328 ret = iio_str_to_fixpoint(buf, 100000, &val, &val2); 329 if (ret) 330 return ret; 331 ret = indio_dev->info->write_event_value(indio_dev, 332 this_attr->c, iio_ev_attr_type(this_attr), 333 iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr), 334 val, val2); 335 if (ret < 0) 336 return ret; 337 338 return len; 339 } 340 341 static int iio_device_add_event(struct iio_dev *indio_dev, 342 const struct iio_chan_spec *chan, unsigned int spec_index, 343 enum iio_event_type type, enum iio_event_direction dir, 344 enum iio_shared_by shared_by, const unsigned long *mask) 345 { 346 ssize_t (*show)(struct device *, struct device_attribute *, char *); 347 ssize_t (*store)(struct device *, struct device_attribute *, 348 const char *, size_t); 349 unsigned int attrcount = 0; 350 unsigned int i; 351 char *postfix; 352 int ret; 353 354 for_each_set_bit(i, mask, sizeof(*mask)*8) { 355 if (i >= ARRAY_SIZE(iio_ev_info_text)) 356 return -EINVAL; 357 if (dir != IIO_EV_DIR_NONE) 358 postfix = kasprintf(GFP_KERNEL, "%s_%s_%s", 359 iio_ev_type_text[type], 360 iio_ev_dir_text[dir], 361 iio_ev_info_text[i]); 362 else 363 postfix = kasprintf(GFP_KERNEL, "%s_%s", 364 iio_ev_type_text[type], 365 iio_ev_info_text[i]); 366 if (postfix == NULL) 367 return -ENOMEM; 368 369 if (i == IIO_EV_INFO_ENABLE) { 370 show = iio_ev_state_show; 371 store = iio_ev_state_store; 372 } else { 373 show = iio_ev_value_show; 374 store = iio_ev_value_store; 375 } 376 377 ret = __iio_add_chan_devattr(postfix, chan, show, store, 378 (i << 16) | spec_index, shared_by, &indio_dev->dev, 379 &indio_dev->event_interface->dev_attr_list); 380 kfree(postfix); 381 382 if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE)) 383 continue; 384 385 if (ret) 386 return ret; 387 388 attrcount++; 389 } 390 391 return attrcount; 392 } 393 394 static int iio_device_add_event_sysfs(struct iio_dev *indio_dev, 395 struct iio_chan_spec const *chan) 396 { 397 int ret = 0, i, attrcount = 0; 398 enum iio_event_direction dir; 399 enum iio_event_type type; 400 401 for (i = 0; i < chan->num_event_specs; i++) { 402 type = chan->event_spec[i].type; 403 dir = chan->event_spec[i].dir; 404 405 ret = iio_device_add_event(indio_dev, chan, i, type, dir, 406 IIO_SEPARATE, &chan->event_spec[i].mask_separate); 407 if (ret < 0) 408 return ret; 409 attrcount += ret; 410 411 ret = iio_device_add_event(indio_dev, chan, i, type, dir, 412 IIO_SHARED_BY_TYPE, 413 &chan->event_spec[i].mask_shared_by_type); 414 if (ret < 0) 415 return ret; 416 attrcount += ret; 417 418 ret = iio_device_add_event(indio_dev, chan, i, type, dir, 419 IIO_SHARED_BY_DIR, 420 &chan->event_spec[i].mask_shared_by_dir); 421 if (ret < 0) 422 return ret; 423 attrcount += ret; 424 425 ret = iio_device_add_event(indio_dev, chan, i, type, dir, 426 IIO_SHARED_BY_ALL, 427 &chan->event_spec[i].mask_shared_by_all); 428 if (ret < 0) 429 return ret; 430 attrcount += ret; 431 } 432 ret = attrcount; 433 return ret; 434 } 435 436 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev) 437 { 438 int j, ret, attrcount = 0; 439 440 /* Dynamically created from the channels array */ 441 for (j = 0; j < indio_dev->num_channels; j++) { 442 ret = iio_device_add_event_sysfs(indio_dev, 443 &indio_dev->channels[j]); 444 if (ret < 0) 445 return ret; 446 attrcount += ret; 447 } 448 return attrcount; 449 } 450 451 static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev) 452 { 453 int j; 454 455 for (j = 0; j < indio_dev->num_channels; j++) { 456 if (indio_dev->channels[j].num_event_specs != 0) 457 return true; 458 } 459 return false; 460 } 461 462 static void iio_setup_ev_int(struct iio_event_interface *ev_int) 463 { 464 INIT_KFIFO(ev_int->det_events); 465 init_waitqueue_head(&ev_int->wait); 466 mutex_init(&ev_int->read_lock); 467 } 468 469 static const char *iio_event_group_name = "events"; 470 int iio_device_register_eventset(struct iio_dev *indio_dev) 471 { 472 struct iio_dev_attr *p; 473 int ret = 0, attrcount_orig = 0, attrcount, attrn; 474 struct attribute **attr; 475 476 if (!(indio_dev->info->event_attrs || 477 iio_check_for_dynamic_events(indio_dev))) 478 return 0; 479 480 indio_dev->event_interface = 481 kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL); 482 if (indio_dev->event_interface == NULL) 483 return -ENOMEM; 484 485 INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list); 486 487 iio_setup_ev_int(indio_dev->event_interface); 488 if (indio_dev->info->event_attrs != NULL) { 489 attr = indio_dev->info->event_attrs->attrs; 490 while (*attr++ != NULL) 491 attrcount_orig++; 492 } 493 attrcount = attrcount_orig; 494 if (indio_dev->channels) { 495 ret = __iio_add_event_config_attrs(indio_dev); 496 if (ret < 0) 497 goto error_free_setup_event_lines; 498 attrcount += ret; 499 } 500 501 indio_dev->event_interface->group.name = iio_event_group_name; 502 indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1, 503 sizeof(indio_dev->event_interface->group.attrs[0]), 504 GFP_KERNEL); 505 if (indio_dev->event_interface->group.attrs == NULL) { 506 ret = -ENOMEM; 507 goto error_free_setup_event_lines; 508 } 509 if (indio_dev->info->event_attrs) 510 memcpy(indio_dev->event_interface->group.attrs, 511 indio_dev->info->event_attrs->attrs, 512 sizeof(indio_dev->event_interface->group.attrs[0]) 513 *attrcount_orig); 514 attrn = attrcount_orig; 515 /* Add all elements from the list. */ 516 list_for_each_entry(p, 517 &indio_dev->event_interface->dev_attr_list, 518 l) 519 indio_dev->event_interface->group.attrs[attrn++] = 520 &p->dev_attr.attr; 521 indio_dev->groups[indio_dev->groupcounter++] = 522 &indio_dev->event_interface->group; 523 524 return 0; 525 526 error_free_setup_event_lines: 527 iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list); 528 kfree(indio_dev->event_interface); 529 indio_dev->event_interface = NULL; 530 return ret; 531 } 532 533 /** 534 * iio_device_wakeup_eventset - Wakes up the event waitqueue 535 * @indio_dev: The IIO device 536 * 537 * Wakes up the event waitqueue used for poll() and blocking read(). 538 * Should usually be called when the device is unregistered. 539 */ 540 void iio_device_wakeup_eventset(struct iio_dev *indio_dev) 541 { 542 if (indio_dev->event_interface == NULL) 543 return; 544 wake_up(&indio_dev->event_interface->wait); 545 } 546 547 void iio_device_unregister_eventset(struct iio_dev *indio_dev) 548 { 549 if (indio_dev->event_interface == NULL) 550 return; 551 iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list); 552 kfree(indio_dev->event_interface->group.attrs); 553 kfree(indio_dev->event_interface); 554 } 555