1#include <linux/idr.h> 2#include <linux/mutex.h> 3#include <linux/device.h> 4#include <linux/sysfs.h> 5#include <linux/gpio/consumer.h> 6#include <linux/gpio/driver.h> 7#include <linux/interrupt.h> 8#include <linux/kdev_t.h> 9 10#include "gpiolib.h" 11 12static DEFINE_IDR(dirent_idr); 13 14 15/* lock protects against unexport_gpio() being called while 16 * sysfs files are active. 17 */ 18static DEFINE_MUTEX(sysfs_lock); 19 20/* 21 * /sys/class/gpio/gpioN... only for GPIOs that are exported 22 * /direction 23 * * MAY BE OMITTED if kernel won't allow direction changes 24 * * is read/write as "in" or "out" 25 * * may also be written as "high" or "low", initializing 26 * output value as specified ("out" implies "low") 27 * /value 28 * * always readable, subject to hardware behavior 29 * * may be writable, as zero/nonzero 30 * /edge 31 * * configures behavior of poll(2) on /value 32 * * available only if pin can generate IRQs on input 33 * * is read/write as "none", "falling", "rising", or "both" 34 * /active_low 35 * * configures polarity of /value 36 * * is read/write as zero/nonzero 37 * * also affects existing and subsequent "falling" and "rising" 38 * /edge configuration 39 */ 40 41static ssize_t gpio_direction_show(struct device *dev, 42 struct device_attribute *attr, char *buf) 43{ 44 struct gpio_desc *desc = dev_get_drvdata(dev); 45 ssize_t status; 46 47 mutex_lock(&sysfs_lock); 48 49 if (!test_bit(FLAG_EXPORT, &desc->flags)) { 50 status = -EIO; 51 } else { 52 gpiod_get_direction(desc); 53 status = sprintf(buf, "%s\n", 54 test_bit(FLAG_IS_OUT, &desc->flags) 55 ? "out" : "in"); 56 } 57 58 mutex_unlock(&sysfs_lock); 59 return status; 60} 61 62static ssize_t gpio_direction_store(struct device *dev, 63 struct device_attribute *attr, const char *buf, size_t size) 64{ 65 struct gpio_desc *desc = dev_get_drvdata(dev); 66 ssize_t status; 67 68 mutex_lock(&sysfs_lock); 69 70 if (!test_bit(FLAG_EXPORT, &desc->flags)) 71 status = -EIO; 72 else if (sysfs_streq(buf, "high")) 73 status = gpiod_direction_output_raw(desc, 1); 74 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low")) 75 status = gpiod_direction_output_raw(desc, 0); 76 else if (sysfs_streq(buf, "in")) 77 status = gpiod_direction_input(desc); 78 else 79 status = -EINVAL; 80 81 mutex_unlock(&sysfs_lock); 82 return status ? : size; 83} 84 85static /* const */ DEVICE_ATTR(direction, 0644, 86 gpio_direction_show, gpio_direction_store); 87 88static ssize_t gpio_value_show(struct device *dev, 89 struct device_attribute *attr, char *buf) 90{ 91 struct gpio_desc *desc = dev_get_drvdata(dev); 92 ssize_t status; 93 94 mutex_lock(&sysfs_lock); 95 96 if (!test_bit(FLAG_EXPORT, &desc->flags)) 97 status = -EIO; 98 else 99 status = sprintf(buf, "%d\n", gpiod_get_value_cansleep(desc)); 100 101 mutex_unlock(&sysfs_lock); 102 return status; 103} 104 105static ssize_t gpio_value_store(struct device *dev, 106 struct device_attribute *attr, const char *buf, size_t size) 107{ 108 struct gpio_desc *desc = dev_get_drvdata(dev); 109 ssize_t status; 110 111 mutex_lock(&sysfs_lock); 112 113 if (!test_bit(FLAG_EXPORT, &desc->flags)) 114 status = -EIO; 115 else if (!test_bit(FLAG_IS_OUT, &desc->flags)) 116 status = -EPERM; 117 else { 118 long value; 119 120 status = kstrtol(buf, 0, &value); 121 if (status == 0) { 122 gpiod_set_value_cansleep(desc, value); 123 status = size; 124 } 125 } 126 127 mutex_unlock(&sysfs_lock); 128 return status; 129} 130 131static DEVICE_ATTR(value, 0644, 132 gpio_value_show, gpio_value_store); 133 134static irqreturn_t gpio_sysfs_irq(int irq, void *priv) 135{ 136 struct kernfs_node *value_sd = priv; 137 138 sysfs_notify_dirent(value_sd); 139 return IRQ_HANDLED; 140} 141 142static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev, 143 unsigned long gpio_flags) 144{ 145 struct kernfs_node *value_sd; 146 unsigned long irq_flags; 147 int ret, irq, id; 148 149 if ((desc->flags & GPIO_TRIGGER_MASK) == gpio_flags) 150 return 0; 151 152 irq = gpiod_to_irq(desc); 153 if (irq < 0) 154 return -EIO; 155 156 id = desc->flags >> ID_SHIFT; 157 value_sd = idr_find(&dirent_idr, id); 158 if (value_sd) 159 free_irq(irq, value_sd); 160 161 desc->flags &= ~GPIO_TRIGGER_MASK; 162 163 if (!gpio_flags) { 164 gpiochip_unlock_as_irq(desc->chip, gpio_chip_hwgpio(desc)); 165 ret = 0; 166 goto free_id; 167 } 168 169 irq_flags = IRQF_SHARED; 170 if (test_bit(FLAG_TRIG_FALL, &gpio_flags)) 171 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ? 172 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING; 173 if (test_bit(FLAG_TRIG_RISE, &gpio_flags)) 174 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ? 175 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING; 176 177 if (!value_sd) { 178 value_sd = sysfs_get_dirent(dev->kobj.sd, "value"); 179 if (!value_sd) { 180 ret = -ENODEV; 181 goto err_out; 182 } 183 184 ret = idr_alloc(&dirent_idr, value_sd, 1, 0, GFP_KERNEL); 185 if (ret < 0) 186 goto free_sd; 187 id = ret; 188 189 desc->flags &= GPIO_FLAGS_MASK; 190 desc->flags |= (unsigned long)id << ID_SHIFT; 191 192 if (desc->flags >> ID_SHIFT != id) { 193 ret = -ERANGE; 194 goto free_id; 195 } 196 } 197 198 ret = request_any_context_irq(irq, gpio_sysfs_irq, irq_flags, 199 "gpiolib", value_sd); 200 if (ret < 0) 201 goto free_id; 202 203 ret = gpiochip_lock_as_irq(desc->chip, gpio_chip_hwgpio(desc)); 204 if (ret < 0) { 205 gpiod_warn(desc, "failed to flag the GPIO for IRQ\n"); 206 goto free_id; 207 } 208 209 desc->flags |= gpio_flags; 210 return 0; 211 212free_id: 213 idr_remove(&dirent_idr, id); 214 desc->flags &= GPIO_FLAGS_MASK; 215free_sd: 216 if (value_sd) 217 sysfs_put(value_sd); 218err_out: 219 return ret; 220} 221 222static const struct { 223 const char *name; 224 unsigned long flags; 225} trigger_types[] = { 226 { "none", 0 }, 227 { "falling", BIT(FLAG_TRIG_FALL) }, 228 { "rising", BIT(FLAG_TRIG_RISE) }, 229 { "both", BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE) }, 230}; 231 232static ssize_t gpio_edge_show(struct device *dev, 233 struct device_attribute *attr, char *buf) 234{ 235 const struct gpio_desc *desc = dev_get_drvdata(dev); 236 ssize_t status; 237 238 mutex_lock(&sysfs_lock); 239 240 if (!test_bit(FLAG_EXPORT, &desc->flags)) 241 status = -EIO; 242 else { 243 int i; 244 245 status = 0; 246 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) 247 if ((desc->flags & GPIO_TRIGGER_MASK) 248 == trigger_types[i].flags) { 249 status = sprintf(buf, "%s\n", 250 trigger_types[i].name); 251 break; 252 } 253 } 254 255 mutex_unlock(&sysfs_lock); 256 return status; 257} 258 259static ssize_t gpio_edge_store(struct device *dev, 260 struct device_attribute *attr, const char *buf, size_t size) 261{ 262 struct gpio_desc *desc = dev_get_drvdata(dev); 263 ssize_t status; 264 int i; 265 266 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) 267 if (sysfs_streq(trigger_types[i].name, buf)) 268 goto found; 269 return -EINVAL; 270 271found: 272 mutex_lock(&sysfs_lock); 273 274 if (!test_bit(FLAG_EXPORT, &desc->flags)) 275 status = -EIO; 276 else { 277 status = gpio_setup_irq(desc, dev, trigger_types[i].flags); 278 if (!status) 279 status = size; 280 } 281 282 mutex_unlock(&sysfs_lock); 283 284 return status; 285} 286 287static DEVICE_ATTR(edge, 0644, gpio_edge_show, gpio_edge_store); 288 289static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev, 290 int value) 291{ 292 int status = 0; 293 294 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value) 295 return 0; 296 297 if (value) 298 set_bit(FLAG_ACTIVE_LOW, &desc->flags); 299 else 300 clear_bit(FLAG_ACTIVE_LOW, &desc->flags); 301 302 /* reconfigure poll(2) support if enabled on one edge only */ 303 if (dev != NULL && (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^ 304 !!test_bit(FLAG_TRIG_FALL, &desc->flags))) { 305 unsigned long trigger_flags = desc->flags & GPIO_TRIGGER_MASK; 306 307 gpio_setup_irq(desc, dev, 0); 308 status = gpio_setup_irq(desc, dev, trigger_flags); 309 } 310 311 return status; 312} 313 314static ssize_t gpio_active_low_show(struct device *dev, 315 struct device_attribute *attr, char *buf) 316{ 317 const struct gpio_desc *desc = dev_get_drvdata(dev); 318 ssize_t status; 319 320 mutex_lock(&sysfs_lock); 321 322 if (!test_bit(FLAG_EXPORT, &desc->flags)) 323 status = -EIO; 324 else 325 status = sprintf(buf, "%d\n", 326 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags)); 327 328 mutex_unlock(&sysfs_lock); 329 330 return status; 331} 332 333static ssize_t gpio_active_low_store(struct device *dev, 334 struct device_attribute *attr, const char *buf, size_t size) 335{ 336 struct gpio_desc *desc = dev_get_drvdata(dev); 337 ssize_t status; 338 339 mutex_lock(&sysfs_lock); 340 341 if (!test_bit(FLAG_EXPORT, &desc->flags)) { 342 status = -EIO; 343 } else { 344 long value; 345 346 status = kstrtol(buf, 0, &value); 347 if (status == 0) 348 status = sysfs_set_active_low(desc, dev, value != 0); 349 } 350 351 mutex_unlock(&sysfs_lock); 352 353 return status ? : size; 354} 355 356static DEVICE_ATTR(active_low, 0644, 357 gpio_active_low_show, gpio_active_low_store); 358 359static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr, 360 int n) 361{ 362 struct device *dev = container_of(kobj, struct device, kobj); 363 struct gpio_desc *desc = dev_get_drvdata(dev); 364 umode_t mode = attr->mode; 365 bool show_direction = test_bit(FLAG_SYSFS_DIR, &desc->flags); 366 367 if (attr == &dev_attr_direction.attr) { 368 if (!show_direction) 369 mode = 0; 370 } else if (attr == &dev_attr_edge.attr) { 371 if (gpiod_to_irq(desc) < 0) 372 mode = 0; 373 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags)) 374 mode = 0; 375 } 376 377 return mode; 378} 379 380static struct attribute *gpio_attrs[] = { 381 &dev_attr_direction.attr, 382 &dev_attr_edge.attr, 383 &dev_attr_value.attr, 384 &dev_attr_active_low.attr, 385 NULL, 386}; 387 388static const struct attribute_group gpio_group = { 389 .attrs = gpio_attrs, 390 .is_visible = gpio_is_visible, 391}; 392 393static const struct attribute_group *gpio_groups[] = { 394 &gpio_group, 395 NULL 396}; 397 398/* 399 * /sys/class/gpio/gpiochipN/ 400 * /base ... matching gpio_chip.base (N) 401 * /label ... matching gpio_chip.label 402 * /ngpio ... matching gpio_chip.ngpio 403 */ 404 405static ssize_t chip_base_show(struct device *dev, 406 struct device_attribute *attr, char *buf) 407{ 408 const struct gpio_chip *chip = dev_get_drvdata(dev); 409 410 return sprintf(buf, "%d\n", chip->base); 411} 412static DEVICE_ATTR(base, 0444, chip_base_show, NULL); 413 414static ssize_t chip_label_show(struct device *dev, 415 struct device_attribute *attr, char *buf) 416{ 417 const struct gpio_chip *chip = dev_get_drvdata(dev); 418 419 return sprintf(buf, "%s\n", chip->label ? : ""); 420} 421static DEVICE_ATTR(label, 0444, chip_label_show, NULL); 422 423static ssize_t chip_ngpio_show(struct device *dev, 424 struct device_attribute *attr, char *buf) 425{ 426 const struct gpio_chip *chip = dev_get_drvdata(dev); 427 428 return sprintf(buf, "%u\n", chip->ngpio); 429} 430static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL); 431 432static struct attribute *gpiochip_attrs[] = { 433 &dev_attr_base.attr, 434 &dev_attr_label.attr, 435 &dev_attr_ngpio.attr, 436 NULL, 437}; 438ATTRIBUTE_GROUPS(gpiochip); 439 440/* 441 * /sys/class/gpio/export ... write-only 442 * integer N ... number of GPIO to export (full access) 443 * /sys/class/gpio/unexport ... write-only 444 * integer N ... number of GPIO to unexport 445 */ 446static ssize_t export_store(struct class *class, 447 struct class_attribute *attr, 448 const char *buf, size_t len) 449{ 450 long gpio; 451 struct gpio_desc *desc; 452 int status; 453 454 status = kstrtol(buf, 0, &gpio); 455 if (status < 0) 456 goto done; 457 458 desc = gpio_to_desc(gpio); 459 /* reject invalid GPIOs */ 460 if (!desc) { 461 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio); 462 return -EINVAL; 463 } 464 465 /* No extra locking here; FLAG_SYSFS just signifies that the 466 * request and export were done by on behalf of userspace, so 467 * they may be undone on its behalf too. 468 */ 469 470 status = gpiod_request(desc, "sysfs"); 471 if (status < 0) { 472 if (status == -EPROBE_DEFER) 473 status = -ENODEV; 474 goto done; 475 } 476 status = gpiod_export(desc, true); 477 if (status < 0) 478 gpiod_free(desc); 479 else 480 set_bit(FLAG_SYSFS, &desc->flags); 481 482done: 483 if (status) 484 pr_debug("%s: status %d\n", __func__, status); 485 return status ? : len; 486} 487 488static ssize_t unexport_store(struct class *class, 489 struct class_attribute *attr, 490 const char *buf, size_t len) 491{ 492 long gpio; 493 struct gpio_desc *desc; 494 int status; 495 496 status = kstrtol(buf, 0, &gpio); 497 if (status < 0) 498 goto done; 499 500 desc = gpio_to_desc(gpio); 501 /* reject bogus commands (gpio_unexport ignores them) */ 502 if (!desc) { 503 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio); 504 return -EINVAL; 505 } 506 507 status = -EINVAL; 508 509 /* No extra locking here; FLAG_SYSFS just signifies that the 510 * request and export were done by on behalf of userspace, so 511 * they may be undone on its behalf too. 512 */ 513 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) { 514 status = 0; 515 gpiod_free(desc); 516 } 517done: 518 if (status) 519 pr_debug("%s: status %d\n", __func__, status); 520 return status ? : len; 521} 522 523static struct class_attribute gpio_class_attrs[] = { 524 __ATTR(export, 0200, NULL, export_store), 525 __ATTR(unexport, 0200, NULL, unexport_store), 526 __ATTR_NULL, 527}; 528 529static struct class gpio_class = { 530 .name = "gpio", 531 .owner = THIS_MODULE, 532 533 .class_attrs = gpio_class_attrs, 534}; 535 536 537/** 538 * gpiod_export - export a GPIO through sysfs 539 * @gpio: gpio to make available, already requested 540 * @direction_may_change: true if userspace may change gpio direction 541 * Context: arch_initcall or later 542 * 543 * When drivers want to make a GPIO accessible to userspace after they 544 * have requested it -- perhaps while debugging, or as part of their 545 * public interface -- they may use this routine. If the GPIO can 546 * change direction (some can't) and the caller allows it, userspace 547 * will see "direction" sysfs attribute which may be used to change 548 * the gpio's direction. A "value" attribute will always be provided. 549 * 550 * Returns zero on success, else an error. 551 */ 552int gpiod_export(struct gpio_desc *desc, bool direction_may_change) 553{ 554 struct gpio_chip *chip; 555 unsigned long flags; 556 int status; 557 const char *ioname = NULL; 558 struct device *dev; 559 int offset; 560 561 /* can't export until sysfs is available ... */ 562 if (!gpio_class.p) { 563 pr_debug("%s: called too early!\n", __func__); 564 return -ENOENT; 565 } 566 567 if (!desc) { 568 pr_debug("%s: invalid gpio descriptor\n", __func__); 569 return -EINVAL; 570 } 571 572 chip = desc->chip; 573 574 mutex_lock(&sysfs_lock); 575 576 /* check if chip is being removed */ 577 if (!chip || !chip->exported) { 578 status = -ENODEV; 579 goto fail_unlock; 580 } 581 582 spin_lock_irqsave(&gpio_lock, flags); 583 if (!test_bit(FLAG_REQUESTED, &desc->flags) || 584 test_bit(FLAG_EXPORT, &desc->flags)) { 585 spin_unlock_irqrestore(&gpio_lock, flags); 586 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n", 587 __func__, 588 test_bit(FLAG_REQUESTED, &desc->flags), 589 test_bit(FLAG_EXPORT, &desc->flags)); 590 status = -EPERM; 591 goto fail_unlock; 592 } 593 594 if (desc->chip->direction_input && desc->chip->direction_output && 595 direction_may_change) { 596 set_bit(FLAG_SYSFS_DIR, &desc->flags); 597 } 598 599 spin_unlock_irqrestore(&gpio_lock, flags); 600 601 offset = gpio_chip_hwgpio(desc); 602 if (desc->chip->names && desc->chip->names[offset]) 603 ioname = desc->chip->names[offset]; 604 605 dev = device_create_with_groups(&gpio_class, desc->chip->dev, 606 MKDEV(0, 0), desc, gpio_groups, 607 ioname ? ioname : "gpio%u", 608 desc_to_gpio(desc)); 609 if (IS_ERR(dev)) { 610 status = PTR_ERR(dev); 611 goto fail_unlock; 612 } 613 614 set_bit(FLAG_EXPORT, &desc->flags); 615 mutex_unlock(&sysfs_lock); 616 return 0; 617 618fail_unlock: 619 mutex_unlock(&sysfs_lock); 620 gpiod_dbg(desc, "%s: status %d\n", __func__, status); 621 return status; 622} 623EXPORT_SYMBOL_GPL(gpiod_export); 624 625static int match_export(struct device *dev, const void *data) 626{ 627 return dev_get_drvdata(dev) == data; 628} 629 630/** 631 * gpiod_export_link - create a sysfs link to an exported GPIO node 632 * @dev: device under which to create symlink 633 * @name: name of the symlink 634 * @gpio: gpio to create symlink to, already exported 635 * 636 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN 637 * node. Caller is responsible for unlinking. 638 * 639 * Returns zero on success, else an error. 640 */ 641int gpiod_export_link(struct device *dev, const char *name, 642 struct gpio_desc *desc) 643{ 644 int status = -EINVAL; 645 646 if (!desc) { 647 pr_warn("%s: invalid GPIO\n", __func__); 648 return -EINVAL; 649 } 650 651 mutex_lock(&sysfs_lock); 652 653 if (test_bit(FLAG_EXPORT, &desc->flags)) { 654 struct device *tdev; 655 656 tdev = class_find_device(&gpio_class, NULL, desc, match_export); 657 if (tdev != NULL) { 658 status = sysfs_create_link(&dev->kobj, &tdev->kobj, 659 name); 660 put_device(tdev); 661 } else { 662 status = -ENODEV; 663 } 664 } 665 666 mutex_unlock(&sysfs_lock); 667 668 if (status) 669 gpiod_dbg(desc, "%s: status %d\n", __func__, status); 670 671 return status; 672} 673EXPORT_SYMBOL_GPL(gpiod_export_link); 674 675/** 676 * gpiod_sysfs_set_active_low - set the polarity of gpio sysfs value 677 * @gpio: gpio to change 678 * @value: non-zero to use active low, i.e. inverted values 679 * 680 * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute. 681 * The GPIO does not have to be exported yet. If poll(2) support has 682 * been enabled for either rising or falling edge, it will be 683 * reconfigured to follow the new polarity. 684 * 685 * Returns zero on success, else an error. 686 */ 687int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value) 688{ 689 struct device *dev = NULL; 690 int status = -EINVAL; 691 692 if (!desc) { 693 pr_warn("%s: invalid GPIO\n", __func__); 694 return -EINVAL; 695 } 696 697 mutex_lock(&sysfs_lock); 698 699 if (test_bit(FLAG_EXPORT, &desc->flags)) { 700 dev = class_find_device(&gpio_class, NULL, desc, match_export); 701 if (dev == NULL) { 702 status = -ENODEV; 703 goto unlock; 704 } 705 } 706 707 status = sysfs_set_active_low(desc, dev, value); 708 put_device(dev); 709unlock: 710 mutex_unlock(&sysfs_lock); 711 712 if (status) 713 gpiod_dbg(desc, "%s: status %d\n", __func__, status); 714 715 return status; 716} 717EXPORT_SYMBOL_GPL(gpiod_sysfs_set_active_low); 718 719/** 720 * gpiod_unexport - reverse effect of gpio_export() 721 * @gpio: gpio to make unavailable 722 * 723 * This is implicit on gpio_free(). 724 */ 725void gpiod_unexport(struct gpio_desc *desc) 726{ 727 int status = 0; 728 struct device *dev = NULL; 729 730 if (!desc) { 731 pr_warn("%s: invalid GPIO\n", __func__); 732 return; 733 } 734 735 mutex_lock(&sysfs_lock); 736 737 if (test_bit(FLAG_EXPORT, &desc->flags)) { 738 739 dev = class_find_device(&gpio_class, NULL, desc, match_export); 740 if (dev) { 741 gpio_setup_irq(desc, dev, 0); 742 clear_bit(FLAG_SYSFS_DIR, &desc->flags); 743 clear_bit(FLAG_EXPORT, &desc->flags); 744 } else 745 status = -ENODEV; 746 } 747 748 mutex_unlock(&sysfs_lock); 749 750 if (dev) { 751 device_unregister(dev); 752 put_device(dev); 753 } 754 755 if (status) 756 gpiod_dbg(desc, "%s: status %d\n", __func__, status); 757} 758EXPORT_SYMBOL_GPL(gpiod_unexport); 759 760int gpiochip_export(struct gpio_chip *chip) 761{ 762 int status; 763 struct device *dev; 764 765 /* Many systems register gpio chips for SOC support very early, 766 * before driver model support is available. In those cases we 767 * export this later, in gpiolib_sysfs_init() ... here we just 768 * verify that _some_ field of gpio_class got initialized. 769 */ 770 if (!gpio_class.p) 771 return 0; 772 773 /* use chip->base for the ID; it's already known to be unique */ 774 mutex_lock(&sysfs_lock); 775 dev = device_create_with_groups(&gpio_class, chip->dev, MKDEV(0, 0), 776 chip, gpiochip_groups, 777 "gpiochip%d", chip->base); 778 if (IS_ERR(dev)) 779 status = PTR_ERR(dev); 780 else 781 status = 0; 782 chip->exported = (status == 0); 783 mutex_unlock(&sysfs_lock); 784 785 if (status) 786 chip_dbg(chip, "%s: status %d\n", __func__, status); 787 788 return status; 789} 790 791void gpiochip_unexport(struct gpio_chip *chip) 792{ 793 int status; 794 struct device *dev; 795 struct gpio_desc *desc; 796 unsigned int i; 797 798 mutex_lock(&sysfs_lock); 799 dev = class_find_device(&gpio_class, NULL, chip, match_export); 800 if (dev) { 801 put_device(dev); 802 device_unregister(dev); 803 /* prevent further gpiod exports */ 804 chip->exported = false; 805 status = 0; 806 } else 807 status = -ENODEV; 808 mutex_unlock(&sysfs_lock); 809 810 if (status) 811 chip_dbg(chip, "%s: status %d\n", __func__, status); 812 813 /* unregister gpiod class devices owned by sysfs */ 814 for (i = 0; i < chip->ngpio; i++) { 815 desc = &chip->desc[i]; 816 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) 817 gpiod_free(desc); 818 } 819} 820 821static int __init gpiolib_sysfs_init(void) 822{ 823 int status; 824 unsigned long flags; 825 struct gpio_chip *chip; 826 827 status = class_register(&gpio_class); 828 if (status < 0) 829 return status; 830 831 /* Scan and register the gpio_chips which registered very 832 * early (e.g. before the class_register above was called). 833 * 834 * We run before arch_initcall() so chip->dev nodes can have 835 * registered, and so arch_initcall() can always gpio_export(). 836 */ 837 spin_lock_irqsave(&gpio_lock, flags); 838 list_for_each_entry(chip, &gpio_chips, list) { 839 if (chip->exported) 840 continue; 841 842 /* 843 * TODO we yield gpio_lock here because gpiochip_export() 844 * acquires a mutex. This is unsafe and needs to be fixed. 845 * 846 * Also it would be nice to use gpiochip_find() here so we 847 * can keep gpio_chips local to gpiolib.c, but the yield of 848 * gpio_lock prevents us from doing this. 849 */ 850 spin_unlock_irqrestore(&gpio_lock, flags); 851 status = gpiochip_export(chip); 852 spin_lock_irqsave(&gpio_lock, flags); 853 } 854 spin_unlock_irqrestore(&gpio_lock, flags); 855 856 857 return status; 858} 859postcore_initcall(gpiolib_sysfs_init); 860