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1// SPDX-License-Identifier: GPL-2.0
2#include <linux/idr.h>
3#include <linux/mutex.h>
4#include <linux/device.h>
5#include <linux/sysfs.h>
6#include <linux/gpio/consumer.h>
7#include <linux/gpio/driver.h>
8#include <linux/interrupt.h>
9#include <linux/kdev_t.h>
10#include <linux/slab.h>
11#include <linux/ctype.h>
12
13#include "gpiolib.h"
14#include "gpiolib-sysfs.h"
15
16#define GPIO_IRQF_TRIGGER_NONE 0
17#define GPIO_IRQF_TRIGGER_FALLING BIT(0)
18#define GPIO_IRQF_TRIGGER_RISING BIT(1)
19#define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
20 GPIO_IRQF_TRIGGER_RISING)
21
22struct gpiod_data {
23 struct gpio_desc *desc;
24
25 struct mutex mutex;
26 struct kernfs_node *value_kn;
27 int irq;
28 unsigned char irq_flags;
29
30 bool direction_can_change;
31};
32
33/*
34 * Lock to serialise gpiod export and unexport, and prevent re-export of
35 * gpiod whose chip is being unregistered.
36 */
37static DEFINE_MUTEX(sysfs_lock);
38
39/*
40 * /sys/class/gpio/gpioN... only for GPIOs that are exported
41 * /direction
42 * * MAY BE OMITTED if kernel won't allow direction changes
43 * * is read/write as "in" or "out"
44 * * may also be written as "high" or "low", initializing
45 * output value as specified ("out" implies "low")
46 * /value
47 * * always readable, subject to hardware behavior
48 * * may be writable, as zero/nonzero
49 * /edge
50 * * configures behavior of poll(2) on /value
51 * * available only if pin can generate IRQs on input
52 * * is read/write as "none", "falling", "rising", or "both"
53 * /active_low
54 * * configures polarity of /value
55 * * is read/write as zero/nonzero
56 * * also affects existing and subsequent "falling" and "rising"
57 * /edge configuration
58 */
59
60static ssize_t direction_show(struct device *dev,
61 struct device_attribute *attr, char *buf)
62{
63 struct gpiod_data *data = dev_get_drvdata(dev);
64 struct gpio_desc *desc = data->desc;
65 int value;
66
67 mutex_lock(&data->mutex);
68
69 gpiod_get_direction(desc);
70 value = !!test_bit(FLAG_IS_OUT, &desc->flags);
71
72 mutex_unlock(&data->mutex);
73
74 return sysfs_emit(buf, "%s\n", value ? "out" : "in");
75}
76
77static ssize_t direction_store(struct device *dev,
78 struct device_attribute *attr, const char *buf, size_t size)
79{
80 struct gpiod_data *data = dev_get_drvdata(dev);
81 struct gpio_desc *desc = data->desc;
82 ssize_t status;
83
84 mutex_lock(&data->mutex);
85
86 if (sysfs_streq(buf, "high"))
87 status = gpiod_direction_output_raw(desc, 1);
88 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
89 status = gpiod_direction_output_raw(desc, 0);
90 else if (sysfs_streq(buf, "in"))
91 status = gpiod_direction_input(desc);
92 else
93 status = -EINVAL;
94
95 mutex_unlock(&data->mutex);
96
97 return status ? : size;
98}
99static DEVICE_ATTR_RW(direction);
100
101static ssize_t value_show(struct device *dev,
102 struct device_attribute *attr, char *buf)
103{
104 struct gpiod_data *data = dev_get_drvdata(dev);
105 struct gpio_desc *desc = data->desc;
106 ssize_t status;
107
108 mutex_lock(&data->mutex);
109
110 status = gpiod_get_value_cansleep(desc);
111
112 mutex_unlock(&data->mutex);
113
114 if (status < 0)
115 return status;
116
117 return sysfs_emit(buf, "%zd\n", status);
118}
119
120static ssize_t value_store(struct device *dev,
121 struct device_attribute *attr, const char *buf, size_t size)
122{
123 struct gpiod_data *data = dev_get_drvdata(dev);
124 struct gpio_desc *desc = data->desc;
125 ssize_t status;
126 long value;
127
128 status = kstrtol(buf, 0, &value);
129
130 mutex_lock(&data->mutex);
131
132 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
133 status = -EPERM;
134 } else if (status == 0) {
135 gpiod_set_value_cansleep(desc, value);
136 status = size;
137 }
138
139 mutex_unlock(&data->mutex);
140
141 return status;
142}
143static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
144
145static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
146{
147 struct gpiod_data *data = priv;
148
149 sysfs_notify_dirent(data->value_kn);
150
151 return IRQ_HANDLED;
152}
153
154/* Caller holds gpiod-data mutex. */
155static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
156{
157 struct gpiod_data *data = dev_get_drvdata(dev);
158 struct gpio_desc *desc = data->desc;
159 unsigned long irq_flags;
160 int ret;
161
162 data->irq = gpiod_to_irq(desc);
163 if (data->irq < 0)
164 return -EIO;
165
166 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
167 if (!data->value_kn)
168 return -ENODEV;
169
170 irq_flags = IRQF_SHARED;
171 if (flags & GPIO_IRQF_TRIGGER_FALLING)
172 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
173 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
174 if (flags & GPIO_IRQF_TRIGGER_RISING)
175 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
176 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
177
178 /*
179 * FIXME: This should be done in the irq_request_resources callback
180 * when the irq is requested, but a few drivers currently fail
181 * to do so.
182 *
183 * Remove this redundant call (along with the corresponding
184 * unlock) when those drivers have been fixed.
185 */
186 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
187 if (ret < 0)
188 goto err_put_kn;
189
190 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
191 "gpiolib", data);
192 if (ret < 0)
193 goto err_unlock;
194
195 data->irq_flags = flags;
196
197 return 0;
198
199err_unlock:
200 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
201err_put_kn:
202 sysfs_put(data->value_kn);
203
204 return ret;
205}
206
207/*
208 * Caller holds gpiod-data mutex (unless called after class-device
209 * deregistration).
210 */
211static void gpio_sysfs_free_irq(struct device *dev)
212{
213 struct gpiod_data *data = dev_get_drvdata(dev);
214 struct gpio_desc *desc = data->desc;
215
216 data->irq_flags = 0;
217 free_irq(data->irq, data);
218 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
219 sysfs_put(data->value_kn);
220}
221
222static const char * const trigger_names[] = {
223 [GPIO_IRQF_TRIGGER_NONE] = "none",
224 [GPIO_IRQF_TRIGGER_FALLING] = "falling",
225 [GPIO_IRQF_TRIGGER_RISING] = "rising",
226 [GPIO_IRQF_TRIGGER_BOTH] = "both",
227};
228
229static ssize_t edge_show(struct device *dev,
230 struct device_attribute *attr, char *buf)
231{
232 struct gpiod_data *data = dev_get_drvdata(dev);
233 int flags;
234
235 mutex_lock(&data->mutex);
236
237 flags = data->irq_flags;
238
239 mutex_unlock(&data->mutex);
240
241 if (flags >= ARRAY_SIZE(trigger_names))
242 return 0;
243
244 return sysfs_emit(buf, "%s\n", trigger_names[flags]);
245}
246
247static ssize_t edge_store(struct device *dev,
248 struct device_attribute *attr, const char *buf, size_t size)
249{
250 struct gpiod_data *data = dev_get_drvdata(dev);
251 ssize_t status = size;
252 int flags;
253
254 flags = sysfs_match_string(trigger_names, buf);
255 if (flags < 0)
256 return flags;
257
258 mutex_lock(&data->mutex);
259
260 if (flags == data->irq_flags) {
261 status = size;
262 goto out_unlock;
263 }
264
265 if (data->irq_flags)
266 gpio_sysfs_free_irq(dev);
267
268 if (flags) {
269 status = gpio_sysfs_request_irq(dev, flags);
270 if (!status)
271 status = size;
272 }
273
274out_unlock:
275 mutex_unlock(&data->mutex);
276
277 return status;
278}
279static DEVICE_ATTR_RW(edge);
280
281/* Caller holds gpiod-data mutex. */
282static int gpio_sysfs_set_active_low(struct device *dev, int value)
283{
284 struct gpiod_data *data = dev_get_drvdata(dev);
285 struct gpio_desc *desc = data->desc;
286 int status = 0;
287 unsigned int flags = data->irq_flags;
288
289 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
290 return 0;
291
292 assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
293
294 /* reconfigure poll(2) support if enabled on one edge only */
295 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
296 flags == GPIO_IRQF_TRIGGER_RISING) {
297 gpio_sysfs_free_irq(dev);
298 status = gpio_sysfs_request_irq(dev, flags);
299 }
300
301 return status;
302}
303
304static ssize_t active_low_show(struct device *dev,
305 struct device_attribute *attr, char *buf)
306{
307 struct gpiod_data *data = dev_get_drvdata(dev);
308 struct gpio_desc *desc = data->desc;
309 int value;
310
311 mutex_lock(&data->mutex);
312
313 value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
314
315 mutex_unlock(&data->mutex);
316
317 return sysfs_emit(buf, "%d\n", value);
318}
319
320static ssize_t active_low_store(struct device *dev,
321 struct device_attribute *attr, const char *buf, size_t size)
322{
323 struct gpiod_data *data = dev_get_drvdata(dev);
324 ssize_t status;
325 long value;
326
327 status = kstrtol(buf, 0, &value);
328 if (status)
329 return status;
330
331 mutex_lock(&data->mutex);
332
333 status = gpio_sysfs_set_active_low(dev, value);
334
335 mutex_unlock(&data->mutex);
336
337 return status ? : size;
338}
339static DEVICE_ATTR_RW(active_low);
340
341static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
342 int n)
343{
344 struct device *dev = kobj_to_dev(kobj);
345 struct gpiod_data *data = dev_get_drvdata(dev);
346 struct gpio_desc *desc = data->desc;
347 umode_t mode = attr->mode;
348 bool show_direction = data->direction_can_change;
349
350 if (attr == &dev_attr_direction.attr) {
351 if (!show_direction)
352 mode = 0;
353 } else if (attr == &dev_attr_edge.attr) {
354 if (gpiod_to_irq(desc) < 0)
355 mode = 0;
356 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
357 mode = 0;
358 }
359
360 return mode;
361}
362
363static struct attribute *gpio_attrs[] = {
364 &dev_attr_direction.attr,
365 &dev_attr_edge.attr,
366 &dev_attr_value.attr,
367 &dev_attr_active_low.attr,
368 NULL,
369};
370
371static const struct attribute_group gpio_group = {
372 .attrs = gpio_attrs,
373 .is_visible = gpio_is_visible,
374};
375
376static const struct attribute_group *gpio_groups[] = {
377 &gpio_group,
378 NULL
379};
380
381/*
382 * /sys/class/gpio/gpiochipN/
383 * /base ... matching gpio_chip.base (N)
384 * /label ... matching gpio_chip.label
385 * /ngpio ... matching gpio_chip.ngpio
386 */
387
388static ssize_t base_show(struct device *dev,
389 struct device_attribute *attr, char *buf)
390{
391 const struct gpio_chip *chip = dev_get_drvdata(dev);
392
393 return sysfs_emit(buf, "%d\n", chip->base);
394}
395static DEVICE_ATTR_RO(base);
396
397static ssize_t label_show(struct device *dev,
398 struct device_attribute *attr, char *buf)
399{
400 const struct gpio_chip *chip = dev_get_drvdata(dev);
401
402 return sysfs_emit(buf, "%s\n", chip->label ?: "");
403}
404static DEVICE_ATTR_RO(label);
405
406static ssize_t ngpio_show(struct device *dev,
407 struct device_attribute *attr, char *buf)
408{
409 const struct gpio_chip *chip = dev_get_drvdata(dev);
410
411 return sysfs_emit(buf, "%u\n", chip->ngpio);
412}
413static DEVICE_ATTR_RO(ngpio);
414
415static struct attribute *gpiochip_attrs[] = {
416 &dev_attr_base.attr,
417 &dev_attr_label.attr,
418 &dev_attr_ngpio.attr,
419 NULL,
420};
421ATTRIBUTE_GROUPS(gpiochip);
422
423/*
424 * /sys/class/gpio/export ... write-only
425 * integer N ... number of GPIO to export (full access)
426 * /sys/class/gpio/unexport ... write-only
427 * integer N ... number of GPIO to unexport
428 */
429static ssize_t export_store(struct class *class,
430 struct class_attribute *attr,
431 const char *buf, size_t len)
432{
433 long gpio;
434 struct gpio_desc *desc;
435 int status;
436 struct gpio_chip *gc;
437 int offset;
438
439 status = kstrtol(buf, 0, &gpio);
440 if (status < 0)
441 goto done;
442
443 desc = gpio_to_desc(gpio);
444 /* reject invalid GPIOs */
445 if (!desc) {
446 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
447 return -EINVAL;
448 }
449 gc = desc->gdev->chip;
450 offset = gpio_chip_hwgpio(desc);
451 if (!gpiochip_line_is_valid(gc, offset)) {
452 pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
453 return -EINVAL;
454 }
455
456 /* No extra locking here; FLAG_SYSFS just signifies that the
457 * request and export were done by on behalf of userspace, so
458 * they may be undone on its behalf too.
459 */
460
461 status = gpiod_request_user(desc, "sysfs");
462 if (status)
463 goto done;
464
465 status = gpiod_set_transitory(desc, false);
466 if (!status) {
467 status = gpiod_export(desc, true);
468 if (status < 0)
469 gpiod_free(desc);
470 else
471 set_bit(FLAG_SYSFS, &desc->flags);
472 }
473
474done:
475 if (status)
476 pr_debug("%s: status %d\n", __func__, status);
477 return status ? : len;
478}
479static CLASS_ATTR_WO(export);
480
481static ssize_t unexport_store(struct class *class,
482 struct class_attribute *attr,
483 const char *buf, size_t len)
484{
485 long gpio;
486 struct gpio_desc *desc;
487 int status;
488
489 status = kstrtol(buf, 0, &gpio);
490 if (status < 0)
491 goto done;
492
493 desc = gpio_to_desc(gpio);
494 /* reject bogus commands (gpio_unexport ignores them) */
495 if (!desc) {
496 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
497 return -EINVAL;
498 }
499
500 status = -EINVAL;
501
502 /* No extra locking here; FLAG_SYSFS just signifies that the
503 * request and export were done by on behalf of userspace, so
504 * they may be undone on its behalf too.
505 */
506 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
507 status = 0;
508 gpiod_free(desc);
509 }
510done:
511 if (status)
512 pr_debug("%s: status %d\n", __func__, status);
513 return status ? : len;
514}
515static CLASS_ATTR_WO(unexport);
516
517static struct attribute *gpio_class_attrs[] = {
518 &class_attr_export.attr,
519 &class_attr_unexport.attr,
520 NULL,
521};
522ATTRIBUTE_GROUPS(gpio_class);
523
524static struct class gpio_class = {
525 .name = "gpio",
526 .owner = THIS_MODULE,
527
528 .class_groups = gpio_class_groups,
529};
530
531
532/**
533 * gpiod_export - export a GPIO through sysfs
534 * @desc: GPIO to make available, already requested
535 * @direction_may_change: true if userspace may change GPIO direction
536 * Context: arch_initcall or later
537 *
538 * When drivers want to make a GPIO accessible to userspace after they
539 * have requested it -- perhaps while debugging, or as part of their
540 * public interface -- they may use this routine. If the GPIO can
541 * change direction (some can't) and the caller allows it, userspace
542 * will see "direction" sysfs attribute which may be used to change
543 * the gpio's direction. A "value" attribute will always be provided.
544 *
545 * Returns zero on success, else an error.
546 */
547int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
548{
549 struct gpio_chip *chip;
550 struct gpio_device *gdev;
551 struct gpiod_data *data;
552 unsigned long flags;
553 int status;
554 const char *ioname = NULL;
555 struct device *dev;
556 int offset;
557
558 /* can't export until sysfs is available ... */
559 if (!gpio_class.p) {
560 pr_debug("%s: called too early!\n", __func__);
561 return -ENOENT;
562 }
563
564 if (!desc) {
565 pr_debug("%s: invalid gpio descriptor\n", __func__);
566 return -EINVAL;
567 }
568
569 gdev = desc->gdev;
570 chip = gdev->chip;
571
572 mutex_lock(&sysfs_lock);
573
574 /* check if chip is being removed */
575 if (!chip || !gdev->mockdev) {
576 status = -ENODEV;
577 goto err_unlock;
578 }
579
580 spin_lock_irqsave(&gpio_lock, flags);
581 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
582 test_bit(FLAG_EXPORT, &desc->flags)) {
583 spin_unlock_irqrestore(&gpio_lock, flags);
584 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
585 __func__,
586 test_bit(FLAG_REQUESTED, &desc->flags),
587 test_bit(FLAG_EXPORT, &desc->flags));
588 status = -EPERM;
589 goto err_unlock;
590 }
591 spin_unlock_irqrestore(&gpio_lock, flags);
592
593 data = kzalloc(sizeof(*data), GFP_KERNEL);
594 if (!data) {
595 status = -ENOMEM;
596 goto err_unlock;
597 }
598
599 data->desc = desc;
600 mutex_init(&data->mutex);
601 if (chip->direction_input && chip->direction_output)
602 data->direction_can_change = direction_may_change;
603 else
604 data->direction_can_change = false;
605
606 offset = gpio_chip_hwgpio(desc);
607 if (chip->names && chip->names[offset])
608 ioname = chip->names[offset];
609
610 dev = device_create_with_groups(&gpio_class, &gdev->dev,
611 MKDEV(0, 0), data, gpio_groups,
612 ioname ? ioname : "gpio%u",
613 desc_to_gpio(desc));
614 if (IS_ERR(dev)) {
615 status = PTR_ERR(dev);
616 goto err_free_data;
617 }
618
619 set_bit(FLAG_EXPORT, &desc->flags);
620 mutex_unlock(&sysfs_lock);
621 return 0;
622
623err_free_data:
624 kfree(data);
625err_unlock:
626 mutex_unlock(&sysfs_lock);
627 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
628 return status;
629}
630EXPORT_SYMBOL_GPL(gpiod_export);
631
632static int match_export(struct device *dev, const void *desc)
633{
634 struct gpiod_data *data = dev_get_drvdata(dev);
635
636 return data->desc == desc;
637}
638
639/**
640 * gpiod_export_link - create a sysfs link to an exported GPIO node
641 * @dev: device under which to create symlink
642 * @name: name of the symlink
643 * @desc: GPIO to create symlink to, already exported
644 *
645 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
646 * node. Caller is responsible for unlinking.
647 *
648 * Returns zero on success, else an error.
649 */
650int gpiod_export_link(struct device *dev, const char *name,
651 struct gpio_desc *desc)
652{
653 struct device *cdev;
654 int ret;
655
656 if (!desc) {
657 pr_warn("%s: invalid GPIO\n", __func__);
658 return -EINVAL;
659 }
660
661 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
662 if (!cdev)
663 return -ENODEV;
664
665 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
666 put_device(cdev);
667
668 return ret;
669}
670EXPORT_SYMBOL_GPL(gpiod_export_link);
671
672/**
673 * gpiod_unexport - reverse effect of gpiod_export()
674 * @desc: GPIO to make unavailable
675 *
676 * This is implicit on gpiod_free().
677 */
678void gpiod_unexport(struct gpio_desc *desc)
679{
680 struct gpiod_data *data;
681 struct device *dev;
682
683 if (!desc) {
684 pr_warn("%s: invalid GPIO\n", __func__);
685 return;
686 }
687
688 mutex_lock(&sysfs_lock);
689
690 if (!test_bit(FLAG_EXPORT, &desc->flags))
691 goto err_unlock;
692
693 dev = class_find_device(&gpio_class, NULL, desc, match_export);
694 if (!dev)
695 goto err_unlock;
696
697 data = dev_get_drvdata(dev);
698
699 clear_bit(FLAG_EXPORT, &desc->flags);
700
701 device_unregister(dev);
702
703 /*
704 * Release irq after deregistration to prevent race with edge_store.
705 */
706 if (data->irq_flags)
707 gpio_sysfs_free_irq(dev);
708
709 mutex_unlock(&sysfs_lock);
710
711 put_device(dev);
712 kfree(data);
713
714 return;
715
716err_unlock:
717 mutex_unlock(&sysfs_lock);
718}
719EXPORT_SYMBOL_GPL(gpiod_unexport);
720
721int gpiochip_sysfs_register(struct gpio_device *gdev)
722{
723 struct device *dev;
724 struct device *parent;
725 struct gpio_chip *chip = gdev->chip;
726
727 /*
728 * Many systems add gpio chips for SOC support very early,
729 * before driver model support is available. In those cases we
730 * register later, in gpiolib_sysfs_init() ... here we just
731 * verify that _some_ field of gpio_class got initialized.
732 */
733 if (!gpio_class.p)
734 return 0;
735
736 /*
737 * For sysfs backward compatibility we need to preserve this
738 * preferred parenting to the gpio_chip parent field, if set.
739 */
740 if (chip->parent)
741 parent = chip->parent;
742 else
743 parent = &gdev->dev;
744
745 /* use chip->base for the ID; it's already known to be unique */
746 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
747 gpiochip_groups, GPIOCHIP_NAME "%d",
748 chip->base);
749 if (IS_ERR(dev))
750 return PTR_ERR(dev);
751
752 mutex_lock(&sysfs_lock);
753 gdev->mockdev = dev;
754 mutex_unlock(&sysfs_lock);
755
756 return 0;
757}
758
759void gpiochip_sysfs_unregister(struct gpio_device *gdev)
760{
761 struct gpio_desc *desc;
762 struct gpio_chip *chip = gdev->chip;
763
764 if (!gdev->mockdev)
765 return;
766
767 device_unregister(gdev->mockdev);
768
769 /* prevent further gpiod exports */
770 mutex_lock(&sysfs_lock);
771 gdev->mockdev = NULL;
772 mutex_unlock(&sysfs_lock);
773
774 /* unregister gpiod class devices owned by sysfs */
775 for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS)
776 gpiod_free(desc);
777}
778
779static int __init gpiolib_sysfs_init(void)
780{
781 int status;
782 unsigned long flags;
783 struct gpio_device *gdev;
784
785 status = class_register(&gpio_class);
786 if (status < 0)
787 return status;
788
789 /* Scan and register the gpio_chips which registered very
790 * early (e.g. before the class_register above was called).
791 *
792 * We run before arch_initcall() so chip->dev nodes can have
793 * registered, and so arch_initcall() can always gpio_export().
794 */
795 spin_lock_irqsave(&gpio_lock, flags);
796 list_for_each_entry(gdev, &gpio_devices, list) {
797 if (gdev->mockdev)
798 continue;
799
800 /*
801 * TODO we yield gpio_lock here because
802 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
803 * and needs to be fixed.
804 *
805 * Also it would be nice to use gpiochip_find() here so we
806 * can keep gpio_chips local to gpiolib.c, but the yield of
807 * gpio_lock prevents us from doing this.
808 */
809 spin_unlock_irqrestore(&gpio_lock, flags);
810 status = gpiochip_sysfs_register(gdev);
811 spin_lock_irqsave(&gpio_lock, flags);
812 }
813 spin_unlock_irqrestore(&gpio_lock, flags);
814
815 return status;
816}
817postcore_initcall(gpiolib_sysfs_init);
1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/bitops.h>
4#include <linux/cleanup.h>
5#include <linux/device.h>
6#include <linux/idr.h>
7#include <linux/init.h>
8#include <linux/interrupt.h>
9#include <linux/kdev_t.h>
10#include <linux/kstrtox.h>
11#include <linux/list.h>
12#include <linux/mutex.h>
13#include <linux/printk.h>
14#include <linux/slab.h>
15#include <linux/spinlock.h>
16#include <linux/string.h>
17#include <linux/srcu.h>
18#include <linux/sysfs.h>
19#include <linux/types.h>
20
21#include <linux/gpio/consumer.h>
22#include <linux/gpio/driver.h>
23
24#include <uapi/linux/gpio.h>
25
26#include "gpiolib.h"
27#include "gpiolib-sysfs.h"
28
29struct kernfs_node;
30
31#define GPIO_IRQF_TRIGGER_NONE 0
32#define GPIO_IRQF_TRIGGER_FALLING BIT(0)
33#define GPIO_IRQF_TRIGGER_RISING BIT(1)
34#define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
35 GPIO_IRQF_TRIGGER_RISING)
36
37struct gpiod_data {
38 struct gpio_desc *desc;
39
40 struct mutex mutex;
41 struct kernfs_node *value_kn;
42 int irq;
43 unsigned char irq_flags;
44
45 bool direction_can_change;
46};
47
48/*
49 * Lock to serialise gpiod export and unexport, and prevent re-export of
50 * gpiod whose chip is being unregistered.
51 */
52static DEFINE_MUTEX(sysfs_lock);
53
54/*
55 * /sys/class/gpio/gpioN... only for GPIOs that are exported
56 * /direction
57 * * MAY BE OMITTED if kernel won't allow direction changes
58 * * is read/write as "in" or "out"
59 * * may also be written as "high" or "low", initializing
60 * output value as specified ("out" implies "low")
61 * /value
62 * * always readable, subject to hardware behavior
63 * * may be writable, as zero/nonzero
64 * /edge
65 * * configures behavior of poll(2) on /value
66 * * available only if pin can generate IRQs on input
67 * * is read/write as "none", "falling", "rising", or "both"
68 * /active_low
69 * * configures polarity of /value
70 * * is read/write as zero/nonzero
71 * * also affects existing and subsequent "falling" and "rising"
72 * /edge configuration
73 */
74
75static ssize_t direction_show(struct device *dev,
76 struct device_attribute *attr, char *buf)
77{
78 struct gpiod_data *data = dev_get_drvdata(dev);
79 struct gpio_desc *desc = data->desc;
80 int value;
81
82 scoped_guard(mutex, &data->mutex) {
83 gpiod_get_direction(desc);
84 value = !!test_bit(FLAG_IS_OUT, &desc->flags);
85 }
86
87 return sysfs_emit(buf, "%s\n", value ? "out" : "in");
88}
89
90static ssize_t direction_store(struct device *dev,
91 struct device_attribute *attr, const char *buf, size_t size)
92{
93 struct gpiod_data *data = dev_get_drvdata(dev);
94 struct gpio_desc *desc = data->desc;
95 ssize_t status;
96
97 guard(mutex)(&data->mutex);
98
99 if (sysfs_streq(buf, "high"))
100 status = gpiod_direction_output_raw(desc, 1);
101 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
102 status = gpiod_direction_output_raw(desc, 0);
103 else if (sysfs_streq(buf, "in"))
104 status = gpiod_direction_input(desc);
105 else
106 status = -EINVAL;
107
108 return status ? : size;
109}
110static DEVICE_ATTR_RW(direction);
111
112static ssize_t value_show(struct device *dev,
113 struct device_attribute *attr, char *buf)
114{
115 struct gpiod_data *data = dev_get_drvdata(dev);
116 struct gpio_desc *desc = data->desc;
117 ssize_t status;
118
119 scoped_guard(mutex, &data->mutex)
120 status = gpiod_get_value_cansleep(desc);
121
122 if (status < 0)
123 return status;
124
125 return sysfs_emit(buf, "%zd\n", status);
126}
127
128static ssize_t value_store(struct device *dev,
129 struct device_attribute *attr, const char *buf, size_t size)
130{
131 struct gpiod_data *data = dev_get_drvdata(dev);
132 struct gpio_desc *desc = data->desc;
133 ssize_t status;
134 long value;
135
136 status = kstrtol(buf, 0, &value);
137
138 guard(mutex)(&data->mutex);
139
140 if (!test_bit(FLAG_IS_OUT, &desc->flags))
141 return -EPERM;
142
143 if (status)
144 return status;
145
146 gpiod_set_value_cansleep(desc, value);
147
148 return size;
149}
150static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
151
152static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
153{
154 struct gpiod_data *data = priv;
155
156 sysfs_notify_dirent(data->value_kn);
157
158 return IRQ_HANDLED;
159}
160
161/* Caller holds gpiod-data mutex. */
162static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
163{
164 struct gpiod_data *data = dev_get_drvdata(dev);
165 struct gpio_desc *desc = data->desc;
166 unsigned long irq_flags;
167 int ret;
168
169 CLASS(gpio_chip_guard, guard)(desc);
170 if (!guard.gc)
171 return -ENODEV;
172
173 data->irq = gpiod_to_irq(desc);
174 if (data->irq < 0)
175 return -EIO;
176
177 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
178 if (!data->value_kn)
179 return -ENODEV;
180
181 irq_flags = IRQF_SHARED;
182 if (flags & GPIO_IRQF_TRIGGER_FALLING) {
183 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
184 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
185 set_bit(FLAG_EDGE_FALLING, &desc->flags);
186 }
187 if (flags & GPIO_IRQF_TRIGGER_RISING) {
188 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
189 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
190 set_bit(FLAG_EDGE_RISING, &desc->flags);
191 }
192
193 /*
194 * FIXME: This should be done in the irq_request_resources callback
195 * when the irq is requested, but a few drivers currently fail
196 * to do so.
197 *
198 * Remove this redundant call (along with the corresponding
199 * unlock) when those drivers have been fixed.
200 */
201 ret = gpiochip_lock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
202 if (ret < 0)
203 goto err_put_kn;
204
205 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
206 "gpiolib", data);
207 if (ret < 0)
208 goto err_unlock;
209
210 data->irq_flags = flags;
211
212 return 0;
213
214err_unlock:
215 gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
216err_put_kn:
217 clear_bit(FLAG_EDGE_RISING, &desc->flags);
218 clear_bit(FLAG_EDGE_FALLING, &desc->flags);
219 sysfs_put(data->value_kn);
220
221 return ret;
222}
223
224/*
225 * Caller holds gpiod-data mutex (unless called after class-device
226 * deregistration).
227 */
228static void gpio_sysfs_free_irq(struct device *dev)
229{
230 struct gpiod_data *data = dev_get_drvdata(dev);
231 struct gpio_desc *desc = data->desc;
232
233 CLASS(gpio_chip_guard, guard)(desc);
234 if (!guard.gc)
235 return;
236
237 data->irq_flags = 0;
238 free_irq(data->irq, data);
239 gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
240 clear_bit(FLAG_EDGE_RISING, &desc->flags);
241 clear_bit(FLAG_EDGE_FALLING, &desc->flags);
242 sysfs_put(data->value_kn);
243}
244
245static const char * const trigger_names[] = {
246 [GPIO_IRQF_TRIGGER_NONE] = "none",
247 [GPIO_IRQF_TRIGGER_FALLING] = "falling",
248 [GPIO_IRQF_TRIGGER_RISING] = "rising",
249 [GPIO_IRQF_TRIGGER_BOTH] = "both",
250};
251
252static ssize_t edge_show(struct device *dev,
253 struct device_attribute *attr, char *buf)
254{
255 struct gpiod_data *data = dev_get_drvdata(dev);
256 int flags;
257
258 scoped_guard(mutex, &data->mutex)
259 flags = data->irq_flags;
260
261 if (flags >= ARRAY_SIZE(trigger_names))
262 return 0;
263
264 return sysfs_emit(buf, "%s\n", trigger_names[flags]);
265}
266
267static ssize_t edge_store(struct device *dev,
268 struct device_attribute *attr, const char *buf, size_t size)
269{
270 struct gpiod_data *data = dev_get_drvdata(dev);
271 ssize_t status = size;
272 int flags;
273
274 flags = sysfs_match_string(trigger_names, buf);
275 if (flags < 0)
276 return flags;
277
278 guard(mutex)(&data->mutex);
279
280 if (flags == data->irq_flags)
281 return size;
282
283 if (data->irq_flags)
284 gpio_sysfs_free_irq(dev);
285
286 if (!flags)
287 return size;
288
289 status = gpio_sysfs_request_irq(dev, flags);
290 if (status)
291 return status;
292
293 gpiod_line_state_notify(data->desc, GPIO_V2_LINE_CHANGED_CONFIG);
294
295 return size;
296}
297static DEVICE_ATTR_RW(edge);
298
299/* Caller holds gpiod-data mutex. */
300static int gpio_sysfs_set_active_low(struct device *dev, int value)
301{
302 struct gpiod_data *data = dev_get_drvdata(dev);
303 unsigned int flags = data->irq_flags;
304 struct gpio_desc *desc = data->desc;
305 int status = 0;
306
307
308 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
309 return 0;
310
311 assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
312
313 /* reconfigure poll(2) support if enabled on one edge only */
314 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
315 flags == GPIO_IRQF_TRIGGER_RISING) {
316 gpio_sysfs_free_irq(dev);
317 status = gpio_sysfs_request_irq(dev, flags);
318 }
319
320 gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_CONFIG);
321
322 return status;
323}
324
325static ssize_t active_low_show(struct device *dev,
326 struct device_attribute *attr, char *buf)
327{
328 struct gpiod_data *data = dev_get_drvdata(dev);
329 struct gpio_desc *desc = data->desc;
330 int value;
331
332 scoped_guard(mutex, &data->mutex)
333 value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
334
335 return sysfs_emit(buf, "%d\n", value);
336}
337
338static ssize_t active_low_store(struct device *dev,
339 struct device_attribute *attr, const char *buf, size_t size)
340{
341 struct gpiod_data *data = dev_get_drvdata(dev);
342 ssize_t status;
343 long value;
344
345 status = kstrtol(buf, 0, &value);
346 if (status)
347 return status;
348
349 guard(mutex)(&data->mutex);
350
351 return gpio_sysfs_set_active_low(dev, value) ?: size;
352}
353static DEVICE_ATTR_RW(active_low);
354
355static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
356 int n)
357{
358 struct device *dev = kobj_to_dev(kobj);
359 struct gpiod_data *data = dev_get_drvdata(dev);
360 struct gpio_desc *desc = data->desc;
361 umode_t mode = attr->mode;
362 bool show_direction = data->direction_can_change;
363
364 if (attr == &dev_attr_direction.attr) {
365 if (!show_direction)
366 mode = 0;
367 } else if (attr == &dev_attr_edge.attr) {
368 if (gpiod_to_irq(desc) < 0)
369 mode = 0;
370 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
371 mode = 0;
372 }
373
374 return mode;
375}
376
377static struct attribute *gpio_attrs[] = {
378 &dev_attr_direction.attr,
379 &dev_attr_edge.attr,
380 &dev_attr_value.attr,
381 &dev_attr_active_low.attr,
382 NULL,
383};
384
385static const struct attribute_group gpio_group = {
386 .attrs = gpio_attrs,
387 .is_visible = gpio_is_visible,
388};
389
390static const struct attribute_group *gpio_groups[] = {
391 &gpio_group,
392 NULL
393};
394
395/*
396 * /sys/class/gpio/gpiochipN/
397 * /base ... matching gpio_chip.base (N)
398 * /label ... matching gpio_chip.label
399 * /ngpio ... matching gpio_chip.ngpio
400 */
401
402static ssize_t base_show(struct device *dev,
403 struct device_attribute *attr, char *buf)
404{
405 const struct gpio_device *gdev = dev_get_drvdata(dev);
406
407 return sysfs_emit(buf, "%u\n", gdev->base);
408}
409static DEVICE_ATTR_RO(base);
410
411static ssize_t label_show(struct device *dev,
412 struct device_attribute *attr, char *buf)
413{
414 const struct gpio_device *gdev = dev_get_drvdata(dev);
415
416 return sysfs_emit(buf, "%s\n", gdev->label);
417}
418static DEVICE_ATTR_RO(label);
419
420static ssize_t ngpio_show(struct device *dev,
421 struct device_attribute *attr, char *buf)
422{
423 const struct gpio_device *gdev = dev_get_drvdata(dev);
424
425 return sysfs_emit(buf, "%u\n", gdev->ngpio);
426}
427static DEVICE_ATTR_RO(ngpio);
428
429static struct attribute *gpiochip_attrs[] = {
430 &dev_attr_base.attr,
431 &dev_attr_label.attr,
432 &dev_attr_ngpio.attr,
433 NULL,
434};
435ATTRIBUTE_GROUPS(gpiochip);
436
437/*
438 * /sys/class/gpio/export ... write-only
439 * integer N ... number of GPIO to export (full access)
440 * /sys/class/gpio/unexport ... write-only
441 * integer N ... number of GPIO to unexport
442 */
443static ssize_t export_store(const struct class *class,
444 const struct class_attribute *attr,
445 const char *buf, size_t len)
446{
447 struct gpio_desc *desc;
448 int status, offset;
449 long gpio;
450
451 status = kstrtol(buf, 0, &gpio);
452 if (status)
453 return status;
454
455 desc = gpio_to_desc(gpio);
456 /* reject invalid GPIOs */
457 if (!desc) {
458 pr_debug_ratelimited("%s: invalid GPIO %ld\n", __func__, gpio);
459 return -EINVAL;
460 }
461
462 CLASS(gpio_chip_guard, guard)(desc);
463 if (!guard.gc)
464 return -ENODEV;
465
466 offset = gpio_chip_hwgpio(desc);
467 if (!gpiochip_line_is_valid(guard.gc, offset)) {
468 pr_debug_ratelimited("%s: GPIO %ld masked\n", __func__, gpio);
469 return -EINVAL;
470 }
471
472 /* No extra locking here; FLAG_SYSFS just signifies that the
473 * request and export were done by on behalf of userspace, so
474 * they may be undone on its behalf too.
475 */
476
477 status = gpiod_request_user(desc, "sysfs");
478 if (status)
479 goto done;
480
481 status = gpiod_set_transitory(desc, false);
482 if (status) {
483 gpiod_free(desc);
484 goto done;
485 }
486
487 status = gpiod_export(desc, true);
488 if (status < 0) {
489 gpiod_free(desc);
490 } else {
491 set_bit(FLAG_SYSFS, &desc->flags);
492 gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_REQUESTED);
493 }
494
495done:
496 if (status)
497 pr_debug("%s: status %d\n", __func__, status);
498 return status ? : len;
499}
500static CLASS_ATTR_WO(export);
501
502static ssize_t unexport_store(const struct class *class,
503 const struct class_attribute *attr,
504 const char *buf, size_t len)
505{
506 struct gpio_desc *desc;
507 int status;
508 long gpio;
509
510 status = kstrtol(buf, 0, &gpio);
511 if (status < 0)
512 goto done;
513
514 desc = gpio_to_desc(gpio);
515 /* reject bogus commands (gpiod_unexport() ignores them) */
516 if (!desc) {
517 pr_debug_ratelimited("%s: invalid GPIO %ld\n", __func__, gpio);
518 return -EINVAL;
519 }
520
521 status = -EINVAL;
522
523 /* No extra locking here; FLAG_SYSFS just signifies that the
524 * request and export were done by on behalf of userspace, so
525 * they may be undone on its behalf too.
526 */
527 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
528 gpiod_unexport(desc);
529 gpiod_free(desc);
530 status = 0;
531 }
532done:
533 if (status)
534 pr_debug("%s: status %d\n", __func__, status);
535 return status ? : len;
536}
537static CLASS_ATTR_WO(unexport);
538
539static struct attribute *gpio_class_attrs[] = {
540 &class_attr_export.attr,
541 &class_attr_unexport.attr,
542 NULL,
543};
544ATTRIBUTE_GROUPS(gpio_class);
545
546static const struct class gpio_class = {
547 .name = "gpio",
548 .class_groups = gpio_class_groups,
549};
550
551/**
552 * gpiod_export - export a GPIO through sysfs
553 * @desc: GPIO to make available, already requested
554 * @direction_may_change: true if userspace may change GPIO direction
555 * Context: arch_initcall or later
556 *
557 * When drivers want to make a GPIO accessible to userspace after they
558 * have requested it -- perhaps while debugging, or as part of their
559 * public interface -- they may use this routine. If the GPIO can
560 * change direction (some can't) and the caller allows it, userspace
561 * will see "direction" sysfs attribute which may be used to change
562 * the gpio's direction. A "value" attribute will always be provided.
563 *
564 * Returns:
565 * 0 on success, or negative errno on failure.
566 */
567int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
568{
569 struct gpio_device *gdev;
570 struct gpiod_data *data;
571 struct device *dev;
572 int status;
573
574 /* can't export until sysfs is available ... */
575 if (!class_is_registered(&gpio_class)) {
576 pr_debug("%s: called too early!\n", __func__);
577 return -ENOENT;
578 }
579
580 if (!desc) {
581 pr_debug("%s: invalid gpio descriptor\n", __func__);
582 return -EINVAL;
583 }
584
585 CLASS(gpio_chip_guard, guard)(desc);
586 if (!guard.gc)
587 return -ENODEV;
588
589 if (test_and_set_bit(FLAG_EXPORT, &desc->flags))
590 return -EPERM;
591
592 gdev = desc->gdev;
593
594 guard(mutex)(&sysfs_lock);
595
596 /* check if chip is being removed */
597 if (!gdev->mockdev) {
598 status = -ENODEV;
599 goto err_clear_bit;
600 }
601
602 if (!test_bit(FLAG_REQUESTED, &desc->flags)) {
603 gpiod_dbg(desc, "%s: unavailable (not requested)\n", __func__);
604 status = -EPERM;
605 goto err_clear_bit;
606 }
607
608 data = kzalloc(sizeof(*data), GFP_KERNEL);
609 if (!data) {
610 status = -ENOMEM;
611 goto err_clear_bit;
612 }
613
614 data->desc = desc;
615 mutex_init(&data->mutex);
616 if (guard.gc->direction_input && guard.gc->direction_output)
617 data->direction_can_change = direction_may_change;
618 else
619 data->direction_can_change = false;
620
621 dev = device_create_with_groups(&gpio_class, &gdev->dev,
622 MKDEV(0, 0), data, gpio_groups,
623 "gpio%u", desc_to_gpio(desc));
624 if (IS_ERR(dev)) {
625 status = PTR_ERR(dev);
626 goto err_free_data;
627 }
628
629 return 0;
630
631err_free_data:
632 kfree(data);
633err_clear_bit:
634 clear_bit(FLAG_EXPORT, &desc->flags);
635 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
636 return status;
637}
638EXPORT_SYMBOL_GPL(gpiod_export);
639
640static int match_export(struct device *dev, const void *desc)
641{
642 struct gpiod_data *data = dev_get_drvdata(dev);
643
644 return data->desc == desc;
645}
646
647/**
648 * gpiod_export_link - create a sysfs link to an exported GPIO node
649 * @dev: device under which to create symlink
650 * @name: name of the symlink
651 * @desc: GPIO to create symlink to, already exported
652 *
653 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
654 * node. Caller is responsible for unlinking.
655 *
656 * Returns:
657 * 0 on success, or negative errno on failure.
658 */
659int gpiod_export_link(struct device *dev, const char *name,
660 struct gpio_desc *desc)
661{
662 struct device *cdev;
663 int ret;
664
665 if (!desc) {
666 pr_warn("%s: invalid GPIO\n", __func__);
667 return -EINVAL;
668 }
669
670 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
671 if (!cdev)
672 return -ENODEV;
673
674 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
675 put_device(cdev);
676
677 return ret;
678}
679EXPORT_SYMBOL_GPL(gpiod_export_link);
680
681/**
682 * gpiod_unexport - reverse effect of gpiod_export()
683 * @desc: GPIO to make unavailable
684 *
685 * This is implicit on gpiod_free().
686 */
687void gpiod_unexport(struct gpio_desc *desc)
688{
689 struct gpiod_data *data;
690 struct device *dev;
691
692 if (!desc) {
693 pr_warn("%s: invalid GPIO\n", __func__);
694 return;
695 }
696
697 scoped_guard(mutex, &sysfs_lock) {
698 if (!test_bit(FLAG_EXPORT, &desc->flags))
699 return;
700
701 dev = class_find_device(&gpio_class, NULL, desc, match_export);
702 if (!dev)
703 return;
704
705 data = dev_get_drvdata(dev);
706 clear_bit(FLAG_EXPORT, &desc->flags);
707 device_unregister(dev);
708
709 /*
710 * Release irq after deregistration to prevent race with
711 * edge_store.
712 */
713 if (data->irq_flags)
714 gpio_sysfs_free_irq(dev);
715 }
716
717 put_device(dev);
718 kfree(data);
719}
720EXPORT_SYMBOL_GPL(gpiod_unexport);
721
722int gpiochip_sysfs_register(struct gpio_device *gdev)
723{
724 struct gpio_chip *chip;
725 struct device *parent;
726 struct device *dev;
727
728 /*
729 * Many systems add gpio chips for SOC support very early,
730 * before driver model support is available. In those cases we
731 * register later, in gpiolib_sysfs_init() ... here we just
732 * verify that _some_ field of gpio_class got initialized.
733 */
734 if (!class_is_registered(&gpio_class))
735 return 0;
736
737 guard(srcu)(&gdev->srcu);
738
739 chip = srcu_dereference(gdev->chip, &gdev->srcu);
740 if (!chip)
741 return -ENODEV;
742
743 /*
744 * For sysfs backward compatibility we need to preserve this
745 * preferred parenting to the gpio_chip parent field, if set.
746 */
747 if (chip->parent)
748 parent = chip->parent;
749 else
750 parent = &gdev->dev;
751
752 /* use chip->base for the ID; it's already known to be unique */
753 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), gdev,
754 gpiochip_groups, GPIOCHIP_NAME "%d",
755 chip->base);
756 if (IS_ERR(dev))
757 return PTR_ERR(dev);
758
759 guard(mutex)(&sysfs_lock);
760 gdev->mockdev = dev;
761
762 return 0;
763}
764
765void gpiochip_sysfs_unregister(struct gpio_device *gdev)
766{
767 struct gpio_desc *desc;
768 struct gpio_chip *chip;
769
770 scoped_guard(mutex, &sysfs_lock) {
771 if (!gdev->mockdev)
772 return;
773
774 device_unregister(gdev->mockdev);
775
776 /* prevent further gpiod exports */
777 gdev->mockdev = NULL;
778 }
779
780 guard(srcu)(&gdev->srcu);
781
782 chip = srcu_dereference(gdev->chip, &gdev->srcu);
783 if (!chip)
784 return;
785
786 /* unregister gpiod class devices owned by sysfs */
787 for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) {
788 gpiod_unexport(desc);
789 gpiod_free(desc);
790 }
791}
792
793/*
794 * We're not really looking for a device - we just want to iterate over the
795 * list and call this callback for each GPIO device. This is why this function
796 * always returns 0.
797 */
798static int gpiofind_sysfs_register(struct gpio_chip *gc, const void *data)
799{
800 struct gpio_device *gdev = gc->gpiodev;
801 int ret;
802
803 if (gdev->mockdev)
804 return 0;
805
806 ret = gpiochip_sysfs_register(gdev);
807 if (ret)
808 chip_err(gc, "failed to register the sysfs entry: %d\n", ret);
809
810 return 0;
811}
812
813static int __init gpiolib_sysfs_init(void)
814{
815 int status;
816
817 status = class_register(&gpio_class);
818 if (status < 0)
819 return status;
820
821 /* Scan and register the gpio_chips which registered very
822 * early (e.g. before the class_register above was called).
823 *
824 * We run before arch_initcall() so chip->dev nodes can have
825 * registered, and so arch_initcall() can always gpiod_export().
826 */
827 (void)gpio_device_find(NULL, gpiofind_sysfs_register);
828
829 return 0;
830}
831postcore_initcall(gpiolib_sysfs_init);