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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 | // SPDX-License-Identifier: GPL-2.0 #include <linux/idr.h> #include <linux/mutex.h> #include <linux/device.h> #include <linux/sysfs.h> #include <linux/gpio/consumer.h> #include <linux/gpio/driver.h> #include <linux/interrupt.h> #include <linux/kdev_t.h> #include <linux/slab.h> #include <linux/ctype.h> #include "gpiolib.h" #include "gpiolib-sysfs.h" #define GPIO_IRQF_TRIGGER_NONE 0 #define GPIO_IRQF_TRIGGER_FALLING BIT(0) #define GPIO_IRQF_TRIGGER_RISING BIT(1) #define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \ GPIO_IRQF_TRIGGER_RISING) struct gpiod_data { struct gpio_desc *desc; struct mutex mutex; struct kernfs_node *value_kn; int irq; unsigned char irq_flags; bool direction_can_change; }; /* * Lock to serialise gpiod export and unexport, and prevent re-export of * gpiod whose chip is being unregistered. */ static DEFINE_MUTEX(sysfs_lock); /* * /sys/class/gpio/gpioN... only for GPIOs that are exported * /direction * * MAY BE OMITTED if kernel won't allow direction changes * * is read/write as "in" or "out" * * may also be written as "high" or "low", initializing * output value as specified ("out" implies "low") * /value * * always readable, subject to hardware behavior * * may be writable, as zero/nonzero * /edge * * configures behavior of poll(2) on /value * * available only if pin can generate IRQs on input * * is read/write as "none", "falling", "rising", or "both" * /active_low * * configures polarity of /value * * is read/write as zero/nonzero * * also affects existing and subsequent "falling" and "rising" * /edge configuration */ static ssize_t direction_show(struct device *dev, struct device_attribute *attr, char *buf) { struct gpiod_data *data = dev_get_drvdata(dev); struct gpio_desc *desc = data->desc; int value; mutex_lock(&data->mutex); gpiod_get_direction(desc); value = !!test_bit(FLAG_IS_OUT, &desc->flags); mutex_unlock(&data->mutex); return sysfs_emit(buf, "%s\n", value ? "out" : "in"); } static ssize_t direction_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t size) { struct gpiod_data *data = dev_get_drvdata(dev); struct gpio_desc *desc = data->desc; ssize_t status; mutex_lock(&data->mutex); if (sysfs_streq(buf, "high")) status = gpiod_direction_output_raw(desc, 1); else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low")) status = gpiod_direction_output_raw(desc, 0); else if (sysfs_streq(buf, "in")) status = gpiod_direction_input(desc); else status = -EINVAL; mutex_unlock(&data->mutex); return status ? : size; } static DEVICE_ATTR_RW(direction); static ssize_t value_show(struct device *dev, struct device_attribute *attr, char *buf) { struct gpiod_data *data = dev_get_drvdata(dev); struct gpio_desc *desc = data->desc; ssize_t status; mutex_lock(&data->mutex); status = gpiod_get_value_cansleep(desc); mutex_unlock(&data->mutex); if (status < 0) return status; return sysfs_emit(buf, "%zd\n", status); } static ssize_t value_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t size) { struct gpiod_data *data = dev_get_drvdata(dev); struct gpio_desc *desc = data->desc; ssize_t status; long value; status = kstrtol(buf, 0, &value); mutex_lock(&data->mutex); if (!test_bit(FLAG_IS_OUT, &desc->flags)) { status = -EPERM; } else if (status == 0) { gpiod_set_value_cansleep(desc, value); status = size; } mutex_unlock(&data->mutex); return status; } static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store); static irqreturn_t gpio_sysfs_irq(int irq, void *priv) { struct gpiod_data *data = priv; sysfs_notify_dirent(data->value_kn); return IRQ_HANDLED; } /* Caller holds gpiod-data mutex. */ static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags) { struct gpiod_data *data = dev_get_drvdata(dev); struct gpio_desc *desc = data->desc; unsigned long irq_flags; int ret; data->irq = gpiod_to_irq(desc); if (data->irq < 0) return -EIO; data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value"); if (!data->value_kn) return -ENODEV; irq_flags = IRQF_SHARED; if (flags & GPIO_IRQF_TRIGGER_FALLING) irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ? IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING; if (flags & GPIO_IRQF_TRIGGER_RISING) irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ? IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING; /* * FIXME: This should be done in the irq_request_resources callback * when the irq is requested, but a few drivers currently fail * to do so. * * Remove this redundant call (along with the corresponding * unlock) when those drivers have been fixed. */ ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc)); if (ret < 0) goto err_put_kn; ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags, "gpiolib", data); if (ret < 0) goto err_unlock; data->irq_flags = flags; return 0; err_unlock: gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc)); err_put_kn: sysfs_put(data->value_kn); return ret; } /* * Caller holds gpiod-data mutex (unless called after class-device * deregistration). */ static void gpio_sysfs_free_irq(struct device *dev) { struct gpiod_data *data = dev_get_drvdata(dev); struct gpio_desc *desc = data->desc; data->irq_flags = 0; free_irq(data->irq, data); gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc)); sysfs_put(data->value_kn); } static const char * const trigger_names[] = { [GPIO_IRQF_TRIGGER_NONE] = "none", [GPIO_IRQF_TRIGGER_FALLING] = "falling", [GPIO_IRQF_TRIGGER_RISING] = "rising", [GPIO_IRQF_TRIGGER_BOTH] = "both", }; static ssize_t edge_show(struct device *dev, struct device_attribute *attr, char *buf) { struct gpiod_data *data = dev_get_drvdata(dev); int flags; mutex_lock(&data->mutex); flags = data->irq_flags; mutex_unlock(&data->mutex); if (flags >= ARRAY_SIZE(trigger_names)) return 0; return sysfs_emit(buf, "%s\n", trigger_names[flags]); } static ssize_t edge_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t size) { struct gpiod_data *data = dev_get_drvdata(dev); ssize_t status = size; int flags; flags = sysfs_match_string(trigger_names, buf); if (flags < 0) return flags; mutex_lock(&data->mutex); if (flags == data->irq_flags) { status = size; goto out_unlock; } if (data->irq_flags) gpio_sysfs_free_irq(dev); if (flags) { status = gpio_sysfs_request_irq(dev, flags); if (!status) status = size; } out_unlock: mutex_unlock(&data->mutex); return status; } static DEVICE_ATTR_RW(edge); /* Caller holds gpiod-data mutex. */ static int gpio_sysfs_set_active_low(struct device *dev, int value) { struct gpiod_data *data = dev_get_drvdata(dev); struct gpio_desc *desc = data->desc; int status = 0; unsigned int flags = data->irq_flags; if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value) return 0; assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value); /* reconfigure poll(2) support if enabled on one edge only */ if (flags == GPIO_IRQF_TRIGGER_FALLING || flags == GPIO_IRQF_TRIGGER_RISING) { gpio_sysfs_free_irq(dev); status = gpio_sysfs_request_irq(dev, flags); } return status; } static ssize_t active_low_show(struct device *dev, struct device_attribute *attr, char *buf) { struct gpiod_data *data = dev_get_drvdata(dev); struct gpio_desc *desc = data->desc; int value; mutex_lock(&data->mutex); value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags); mutex_unlock(&data->mutex); return sysfs_emit(buf, "%d\n", value); } static ssize_t active_low_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t size) { struct gpiod_data *data = dev_get_drvdata(dev); ssize_t status; long value; status = kstrtol(buf, 0, &value); if (status) return status; mutex_lock(&data->mutex); status = gpio_sysfs_set_active_low(dev, value); mutex_unlock(&data->mutex); return status ? : size; } static DEVICE_ATTR_RW(active_low); static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr, int n) { struct device *dev = kobj_to_dev(kobj); struct gpiod_data *data = dev_get_drvdata(dev); struct gpio_desc *desc = data->desc; umode_t mode = attr->mode; bool show_direction = data->direction_can_change; if (attr == &dev_attr_direction.attr) { if (!show_direction) mode = 0; } else if (attr == &dev_attr_edge.attr) { if (gpiod_to_irq(desc) < 0) mode = 0; if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags)) mode = 0; } return mode; } static struct attribute *gpio_attrs[] = { &dev_attr_direction.attr, &dev_attr_edge.attr, &dev_attr_value.attr, &dev_attr_active_low.attr, NULL, }; static const struct attribute_group gpio_group = { .attrs = gpio_attrs, .is_visible = gpio_is_visible, }; static const struct attribute_group *gpio_groups[] = { &gpio_group, NULL }; /* * /sys/class/gpio/gpiochipN/ * /base ... matching gpio_chip.base (N) * /label ... matching gpio_chip.label * /ngpio ... matching gpio_chip.ngpio */ static ssize_t base_show(struct device *dev, struct device_attribute *attr, char *buf) { const struct gpio_chip *chip = dev_get_drvdata(dev); return sysfs_emit(buf, "%d\n", chip->base); } static DEVICE_ATTR_RO(base); static ssize_t label_show(struct device *dev, struct device_attribute *attr, char *buf) { const struct gpio_chip *chip = dev_get_drvdata(dev); return sysfs_emit(buf, "%s\n", chip->label ?: ""); } static DEVICE_ATTR_RO(label); static ssize_t ngpio_show(struct device *dev, struct device_attribute *attr, char *buf) { const struct gpio_chip *chip = dev_get_drvdata(dev); return sysfs_emit(buf, "%u\n", chip->ngpio); } static DEVICE_ATTR_RO(ngpio); static struct attribute *gpiochip_attrs[] = { &dev_attr_base.attr, &dev_attr_label.attr, &dev_attr_ngpio.attr, NULL, }; ATTRIBUTE_GROUPS(gpiochip); /* * /sys/class/gpio/export ... write-only * integer N ... number of GPIO to export (full access) * /sys/class/gpio/unexport ... write-only * integer N ... number of GPIO to unexport */ static ssize_t export_store(struct class *class, struct class_attribute *attr, const char *buf, size_t len) { long gpio; struct gpio_desc *desc; int status; struct gpio_chip *gc; int offset; status = kstrtol(buf, 0, &gpio); if (status < 0) goto done; desc = gpio_to_desc(gpio); /* reject invalid GPIOs */ if (!desc) { pr_warn("%s: invalid GPIO %ld\n", __func__, gpio); return -EINVAL; } gc = desc->gdev->chip; offset = gpio_chip_hwgpio(desc); if (!gpiochip_line_is_valid(gc, offset)) { pr_warn("%s: GPIO %ld masked\n", __func__, gpio); return -EINVAL; } /* No extra locking here; FLAG_SYSFS just signifies that the * request and export were done by on behalf of userspace, so * they may be undone on its behalf too. */ status = gpiod_request_user(desc, "sysfs"); if (status) goto done; status = gpiod_set_transitory(desc, false); if (!status) { status = gpiod_export(desc, true); if (status < 0) gpiod_free(desc); else set_bit(FLAG_SYSFS, &desc->flags); } done: if (status) pr_debug("%s: status %d\n", __func__, status); return status ? : len; } static CLASS_ATTR_WO(export); static ssize_t unexport_store(struct class *class, struct class_attribute *attr, const char *buf, size_t len) { long gpio; struct gpio_desc *desc; int status; status = kstrtol(buf, 0, &gpio); if (status < 0) goto done; desc = gpio_to_desc(gpio); /* reject bogus commands (gpio_unexport ignores them) */ if (!desc) { pr_warn("%s: invalid GPIO %ld\n", __func__, gpio); return -EINVAL; } status = -EINVAL; /* No extra locking here; FLAG_SYSFS just signifies that the * request and export were done by on behalf of userspace, so * they may be undone on its behalf too. */ if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) { status = 0; gpiod_free(desc); } done: if (status) pr_debug("%s: status %d\n", __func__, status); return status ? : len; } static CLASS_ATTR_WO(unexport); static struct attribute *gpio_class_attrs[] = { &class_attr_export.attr, &class_attr_unexport.attr, NULL, }; ATTRIBUTE_GROUPS(gpio_class); static struct class gpio_class = { .name = "gpio", .owner = THIS_MODULE, .class_groups = gpio_class_groups, }; /** * gpiod_export - export a GPIO through sysfs * @desc: GPIO to make available, already requested * @direction_may_change: true if userspace may change GPIO direction * Context: arch_initcall or later * * When drivers want to make a GPIO accessible to userspace after they * have requested it -- perhaps while debugging, or as part of their * public interface -- they may use this routine. If the GPIO can * change direction (some can't) and the caller allows it, userspace * will see "direction" sysfs attribute which may be used to change * the gpio's direction. A "value" attribute will always be provided. * * Returns zero on success, else an error. */ int gpiod_export(struct gpio_desc *desc, bool direction_may_change) { struct gpio_chip *chip; struct gpio_device *gdev; struct gpiod_data *data; unsigned long flags; int status; const char *ioname = NULL; struct device *dev; int offset; /* can't export until sysfs is available ... */ if (!gpio_class.p) { pr_debug("%s: called too early!\n", __func__); return -ENOENT; } if (!desc) { pr_debug("%s: invalid gpio descriptor\n", __func__); return -EINVAL; } gdev = desc->gdev; chip = gdev->chip; mutex_lock(&sysfs_lock); /* check if chip is being removed */ if (!chip || !gdev->mockdev) { status = -ENODEV; goto err_unlock; } spin_lock_irqsave(&gpio_lock, flags); if (!test_bit(FLAG_REQUESTED, &desc->flags) || test_bit(FLAG_EXPORT, &desc->flags)) { spin_unlock_irqrestore(&gpio_lock, flags); gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n", __func__, test_bit(FLAG_REQUESTED, &desc->flags), test_bit(FLAG_EXPORT, &desc->flags)); status = -EPERM; goto err_unlock; } spin_unlock_irqrestore(&gpio_lock, flags); data = kzalloc(sizeof(*data), GFP_KERNEL); if (!data) { status = -ENOMEM; goto err_unlock; } data->desc = desc; mutex_init(&data->mutex); if (chip->direction_input && chip->direction_output) data->direction_can_change = direction_may_change; else data->direction_can_change = false; offset = gpio_chip_hwgpio(desc); if (chip->names && chip->names[offset]) ioname = chip->names[offset]; dev = device_create_with_groups(&gpio_class, &gdev->dev, MKDEV(0, 0), data, gpio_groups, ioname ? ioname : "gpio%u", desc_to_gpio(desc)); if (IS_ERR(dev)) { status = PTR_ERR(dev); goto err_free_data; } set_bit(FLAG_EXPORT, &desc->flags); mutex_unlock(&sysfs_lock); return 0; err_free_data: kfree(data); err_unlock: mutex_unlock(&sysfs_lock); gpiod_dbg(desc, "%s: status %d\n", __func__, status); return status; } EXPORT_SYMBOL_GPL(gpiod_export); static int match_export(struct device *dev, const void *desc) { struct gpiod_data *data = dev_get_drvdata(dev); return data->desc == desc; } /** * gpiod_export_link - create a sysfs link to an exported GPIO node * @dev: device under which to create symlink * @name: name of the symlink * @desc: GPIO to create symlink to, already exported * * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN * node. Caller is responsible for unlinking. * * Returns zero on success, else an error. */ int gpiod_export_link(struct device *dev, const char *name, struct gpio_desc *desc) { struct device *cdev; int ret; if (!desc) { pr_warn("%s: invalid GPIO\n", __func__); return -EINVAL; } cdev = class_find_device(&gpio_class, NULL, desc, match_export); if (!cdev) return -ENODEV; ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name); put_device(cdev); return ret; } EXPORT_SYMBOL_GPL(gpiod_export_link); /** * gpiod_unexport - reverse effect of gpiod_export() * @desc: GPIO to make unavailable * * This is implicit on gpiod_free(). */ void gpiod_unexport(struct gpio_desc *desc) { struct gpiod_data *data; struct device *dev; if (!desc) { pr_warn("%s: invalid GPIO\n", __func__); return; } mutex_lock(&sysfs_lock); if (!test_bit(FLAG_EXPORT, &desc->flags)) goto err_unlock; dev = class_find_device(&gpio_class, NULL, desc, match_export); if (!dev) goto err_unlock; data = dev_get_drvdata(dev); clear_bit(FLAG_EXPORT, &desc->flags); device_unregister(dev); /* * Release irq after deregistration to prevent race with edge_store. */ if (data->irq_flags) gpio_sysfs_free_irq(dev); mutex_unlock(&sysfs_lock); put_device(dev); kfree(data); return; err_unlock: mutex_unlock(&sysfs_lock); } EXPORT_SYMBOL_GPL(gpiod_unexport); int gpiochip_sysfs_register(struct gpio_device *gdev) { struct device *dev; struct device *parent; struct gpio_chip *chip = gdev->chip; /* * Many systems add gpio chips for SOC support very early, * before driver model support is available. In those cases we * register later, in gpiolib_sysfs_init() ... here we just * verify that _some_ field of gpio_class got initialized. */ if (!gpio_class.p) return 0; /* * For sysfs backward compatibility we need to preserve this * preferred parenting to the gpio_chip parent field, if set. */ if (chip->parent) parent = chip->parent; else parent = &gdev->dev; /* use chip->base for the ID; it's already known to be unique */ dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip, gpiochip_groups, GPIOCHIP_NAME "%d", chip->base); if (IS_ERR(dev)) return PTR_ERR(dev); mutex_lock(&sysfs_lock); gdev->mockdev = dev; mutex_unlock(&sysfs_lock); return 0; } void gpiochip_sysfs_unregister(struct gpio_device *gdev) { struct gpio_desc *desc; struct gpio_chip *chip = gdev->chip; if (!gdev->mockdev) return; device_unregister(gdev->mockdev); /* prevent further gpiod exports */ mutex_lock(&sysfs_lock); gdev->mockdev = NULL; mutex_unlock(&sysfs_lock); /* unregister gpiod class devices owned by sysfs */ for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) gpiod_free(desc); } static int __init gpiolib_sysfs_init(void) { int status; unsigned long flags; struct gpio_device *gdev; status = class_register(&gpio_class); if (status < 0) return status; /* Scan and register the gpio_chips which registered very * early (e.g. before the class_register above was called). * * We run before arch_initcall() so chip->dev nodes can have * registered, and so arch_initcall() can always gpio_export(). */ spin_lock_irqsave(&gpio_lock, flags); list_for_each_entry(gdev, &gpio_devices, list) { if (gdev->mockdev) continue; /* * TODO we yield gpio_lock here because * gpiochip_sysfs_register() acquires a mutex. This is unsafe * and needs to be fixed. * * Also it would be nice to use gpiochip_find() here so we * can keep gpio_chips local to gpiolib.c, but the yield of * gpio_lock prevents us from doing this. */ spin_unlock_irqrestore(&gpio_lock, flags); status = gpiochip_sysfs_register(gdev); spin_lock_irqsave(&gpio_lock, flags); } spin_unlock_irqrestore(&gpio_lock, flags); return status; } postcore_initcall(gpiolib_sysfs_init); |