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 "gpiolib.h"
25#include "gpiolib-sysfs.h"
26
27struct kernfs_node;
28
29#define GPIO_IRQF_TRIGGER_NONE		0
30#define GPIO_IRQF_TRIGGER_FALLING	BIT(0)
31#define GPIO_IRQF_TRIGGER_RISING	BIT(1)
32#define GPIO_IRQF_TRIGGER_BOTH		(GPIO_IRQF_TRIGGER_FALLING | \
33					 GPIO_IRQF_TRIGGER_RISING)
34
35struct gpiod_data {
36	struct gpio_desc *desc;
37
38	struct mutex mutex;
39	struct kernfs_node *value_kn;
40	int irq;
41	unsigned char irq_flags;
42
43	bool direction_can_change;
44};
45
46/*
47 * Lock to serialise gpiod export and unexport, and prevent re-export of
48 * gpiod whose chip is being unregistered.
49 */
50static DEFINE_MUTEX(sysfs_lock);
51
52/*
53 * /sys/class/gpio/gpioN... only for GPIOs that are exported
54 *   /direction
55 *      * MAY BE OMITTED if kernel won't allow direction changes
56 *      * is read/write as "in" or "out"
57 *      * may also be written as "high" or "low", initializing
58 *        output value as specified ("out" implies "low")
59 *   /value
60 *      * always readable, subject to hardware behavior
61 *      * may be writable, as zero/nonzero
62 *   /edge
63 *      * configures behavior of poll(2) on /value
64 *      * available only if pin can generate IRQs on input
65 *      * is read/write as "none", "falling", "rising", or "both"
66 *   /active_low
67 *      * configures polarity of /value
68 *      * is read/write as zero/nonzero
69 *      * also affects existing and subsequent "falling" and "rising"
70 *        /edge configuration
71 */
72
73static ssize_t direction_show(struct device *dev,
74		struct device_attribute *attr, char *buf)
75{
76	struct gpiod_data *data = dev_get_drvdata(dev);
77	struct gpio_desc *desc = data->desc;
78	int value;
79
80	mutex_lock(&data->mutex);
81
82	gpiod_get_direction(desc);
83	value = !!test_bit(FLAG_IS_OUT, &desc->flags);
84
85	mutex_unlock(&data->mutex);
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	mutex_lock(&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	mutex_unlock(&data->mutex);
109
110	return status ? : size;
111}
112static DEVICE_ATTR_RW(direction);
113
114static ssize_t value_show(struct device *dev,
115		struct device_attribute *attr, char *buf)
116{
117	struct gpiod_data *data = dev_get_drvdata(dev);
118	struct gpio_desc *desc = data->desc;
119	ssize_t			status;
120
121	mutex_lock(&data->mutex);
122
123	status = gpiod_get_value_cansleep(desc);
124
125	mutex_unlock(&data->mutex);
126
127	if (status < 0)
128		return status;
129
130	return sysfs_emit(buf, "%zd\n", status);
131}
132
133static ssize_t value_store(struct device *dev,
134		struct device_attribute *attr, const char *buf, size_t size)
135{
136	struct gpiod_data *data = dev_get_drvdata(dev);
137	struct gpio_desc *desc = data->desc;
138	ssize_t status;
139	long value;
140
141	status = kstrtol(buf, 0, &value);
142
143	mutex_lock(&data->mutex);
144
145	if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
146		status = -EPERM;
147	} else if (status == 0) {
148		gpiod_set_value_cansleep(desc, value);
149		status = size;
150	}
151
152	mutex_unlock(&data->mutex);
153
154	return status;
155}
156static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
157
158static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
159{
160	struct gpiod_data *data = priv;
161
162	sysfs_notify_dirent(data->value_kn);
163
164	return IRQ_HANDLED;
165}
166
167/* Caller holds gpiod-data mutex. */
168static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
169{
170	struct gpiod_data *data = dev_get_drvdata(dev);
171	struct gpio_desc *desc = data->desc;
172	unsigned long irq_flags;
173	int ret;
174
175	CLASS(gpio_chip_guard, guard)(desc);
176	if (!guard.gc)
177		return -ENODEV;
178
179	data->irq = gpiod_to_irq(desc);
180	if (data->irq < 0)
181		return -EIO;
182
183	data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
184	if (!data->value_kn)
185		return -ENODEV;
186
187	irq_flags = IRQF_SHARED;
188	if (flags & GPIO_IRQF_TRIGGER_FALLING)
189		irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
190			IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
191	if (flags & GPIO_IRQF_TRIGGER_RISING)
192		irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
193			IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
194
195	/*
196	 * FIXME: This should be done in the irq_request_resources callback
197	 *        when the irq is requested, but a few drivers currently fail
198	 *        to do so.
199	 *
200	 *        Remove this redundant call (along with the corresponding
201	 *        unlock) when those drivers have been fixed.
202	 */
203	ret = gpiochip_lock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
204	if (ret < 0)
205		goto err_put_kn;
206
207	ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
208				"gpiolib", data);
209	if (ret < 0)
210		goto err_unlock;
211
212	data->irq_flags = flags;
213
214	return 0;
215
216err_unlock:
217	gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
218err_put_kn:
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	sysfs_put(data->value_kn);
241}
242
243static const char * const trigger_names[] = {
244	[GPIO_IRQF_TRIGGER_NONE]	= "none",
245	[GPIO_IRQF_TRIGGER_FALLING]	= "falling",
246	[GPIO_IRQF_TRIGGER_RISING]	= "rising",
247	[GPIO_IRQF_TRIGGER_BOTH]	= "both",
248};
249
250static ssize_t edge_show(struct device *dev,
251		struct device_attribute *attr, char *buf)
252{
253	struct gpiod_data *data = dev_get_drvdata(dev);
254	int flags;
255
256	mutex_lock(&data->mutex);
257
258	flags = data->irq_flags;
259
260	mutex_unlock(&data->mutex);
261
262	if (flags >= ARRAY_SIZE(trigger_names))
263		return 0;
264
265	return sysfs_emit(buf, "%s\n", trigger_names[flags]);
266}
267
268static ssize_t edge_store(struct device *dev,
269		struct device_attribute *attr, const char *buf, size_t size)
270{
271	struct gpiod_data *data = dev_get_drvdata(dev);
272	ssize_t status = size;
273	int flags;
274
275	flags = sysfs_match_string(trigger_names, buf);
276	if (flags < 0)
277		return flags;
278
279	mutex_lock(&data->mutex);
280
281	if (flags == data->irq_flags) {
282		status = size;
283		goto out_unlock;
284	}
285
286	if (data->irq_flags)
287		gpio_sysfs_free_irq(dev);
288
289	if (flags) {
290		status = gpio_sysfs_request_irq(dev, flags);
291		if (!status)
292			status = size;
293	}
294
295out_unlock:
296	mutex_unlock(&data->mutex);
297
298	return status;
299}
300static DEVICE_ATTR_RW(edge);
301
302/* Caller holds gpiod-data mutex. */
303static int gpio_sysfs_set_active_low(struct device *dev, int value)
304{
305	struct gpiod_data *data = dev_get_drvdata(dev);
306	unsigned int flags = data->irq_flags;
307	struct gpio_desc *desc = data->desc;
308	int status = 0;
309
310
311	if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
312		return 0;
313
314	assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
315
316	/* reconfigure poll(2) support if enabled on one edge only */
317	if (flags == GPIO_IRQF_TRIGGER_FALLING ||
318					flags == GPIO_IRQF_TRIGGER_RISING) {
319		gpio_sysfs_free_irq(dev);
320		status = gpio_sysfs_request_irq(dev, flags);
321	}
322
323	return status;
324}
325
326static ssize_t active_low_show(struct device *dev,
327		struct device_attribute *attr, char *buf)
328{
329	struct gpiod_data *data = dev_get_drvdata(dev);
330	struct gpio_desc *desc = data->desc;
331	int value;
332
333	mutex_lock(&data->mutex);
334
335	value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
336
337	mutex_unlock(&data->mutex);
338
339	return sysfs_emit(buf, "%d\n", value);
340}
341
342static ssize_t active_low_store(struct device *dev,
343		struct device_attribute *attr, const char *buf, size_t size)
344{
345	struct gpiod_data *data = dev_get_drvdata(dev);
346	ssize_t status;
347	long value;
348
349	status = kstrtol(buf, 0, &value);
350	if (status)
351		return status;
352
353	mutex_lock(&data->mutex);
354
355	status = gpio_sysfs_set_active_low(dev, value);
356
357	mutex_unlock(&data->mutex);
358
359	return status ? : size;
360}
361static DEVICE_ATTR_RW(active_low);
362
363static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
364			       int n)
365{
366	struct device *dev = kobj_to_dev(kobj);
367	struct gpiod_data *data = dev_get_drvdata(dev);
368	struct gpio_desc *desc = data->desc;
369	umode_t mode = attr->mode;
370	bool show_direction = data->direction_can_change;
371
372	if (attr == &dev_attr_direction.attr) {
373		if (!show_direction)
374			mode = 0;
375	} else if (attr == &dev_attr_edge.attr) {
376		if (gpiod_to_irq(desc) < 0)
377			mode = 0;
378		if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
379			mode = 0;
380	}
381
382	return mode;
383}
384
385static struct attribute *gpio_attrs[] = {
386	&dev_attr_direction.attr,
387	&dev_attr_edge.attr,
388	&dev_attr_value.attr,
389	&dev_attr_active_low.attr,
390	NULL,
391};
392
393static const struct attribute_group gpio_group = {
394	.attrs = gpio_attrs,
395	.is_visible = gpio_is_visible,
396};
397
398static const struct attribute_group *gpio_groups[] = {
399	&gpio_group,
400	NULL
401};
402
403/*
404 * /sys/class/gpio/gpiochipN/
405 *   /base ... matching gpio_chip.base (N)
406 *   /label ... matching gpio_chip.label
407 *   /ngpio ... matching gpio_chip.ngpio
408 */
409
410static ssize_t base_show(struct device *dev,
411			       struct device_attribute *attr, char *buf)
412{
413	const struct gpio_device *gdev = dev_get_drvdata(dev);
414
415	return sysfs_emit(buf, "%u\n", gdev->base);
416}
417static DEVICE_ATTR_RO(base);
418
419static ssize_t label_show(struct device *dev,
420			       struct device_attribute *attr, char *buf)
421{
422	const struct gpio_device *gdev = dev_get_drvdata(dev);
423
424	return sysfs_emit(buf, "%s\n", gdev->label);
425}
426static DEVICE_ATTR_RO(label);
427
428static ssize_t ngpio_show(struct device *dev,
429			       struct device_attribute *attr, char *buf)
430{
431	const struct gpio_device *gdev = dev_get_drvdata(dev);
432
433	return sysfs_emit(buf, "%u\n", gdev->ngpio);
434}
435static DEVICE_ATTR_RO(ngpio);
436
437static struct attribute *gpiochip_attrs[] = {
438	&dev_attr_base.attr,
439	&dev_attr_label.attr,
440	&dev_attr_ngpio.attr,
441	NULL,
442};
443ATTRIBUTE_GROUPS(gpiochip);
444
445/*
446 * /sys/class/gpio/export ... write-only
447 *	integer N ... number of GPIO to export (full access)
448 * /sys/class/gpio/unexport ... write-only
449 *	integer N ... number of GPIO to unexport
450 */
451static ssize_t export_store(const struct class *class,
452				const struct class_attribute *attr,
453				const char *buf, size_t len)
454{
455	struct gpio_desc *desc;
456	int status, offset;
457	long gpio;
458
459	status = kstrtol(buf, 0, &gpio);
460	if (status)
461		return status;
462
463	desc = gpio_to_desc(gpio);
464	/* reject invalid GPIOs */
465	if (!desc) {
466		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
467		return -EINVAL;
468	}
469
470	CLASS(gpio_chip_guard, guard)(desc);
471	if (!guard.gc)
472		return -ENODEV;
473
474	offset = gpio_chip_hwgpio(desc);
475	if (!gpiochip_line_is_valid(guard.gc, offset)) {
476		pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
477		return -EINVAL;
478	}
479
480	/* No extra locking here; FLAG_SYSFS just signifies that the
481	 * request and export were done by on behalf of userspace, so
482	 * they may be undone on its behalf too.
483	 */
484
485	status = gpiod_request_user(desc, "sysfs");
486	if (status)
487		goto done;
488
489	status = gpiod_set_transitory(desc, false);
490	if (status) {
491		gpiod_free(desc);
492		goto done;
493	}
494
495	status = gpiod_export(desc, true);
496	if (status < 0)
497		gpiod_free(desc);
498	else
499		set_bit(FLAG_SYSFS, &desc->flags);
500
501done:
502	if (status)
503		pr_debug("%s: status %d\n", __func__, status);
504	return status ? : len;
505}
506static CLASS_ATTR_WO(export);
507
508static ssize_t unexport_store(const struct class *class,
509				const struct class_attribute *attr,
510				const char *buf, size_t len)
511{
512	struct gpio_desc *desc;
513	int status;
514	long gpio;
515
516	status = kstrtol(buf, 0, &gpio);
517	if (status < 0)
518		goto done;
519
520	desc = gpio_to_desc(gpio);
521	/* reject bogus commands (gpiod_unexport() ignores them) */
522	if (!desc) {
523		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
524		return -EINVAL;
525	}
526
527	status = -EINVAL;
528
529	/* No extra locking here; FLAG_SYSFS just signifies that the
530	 * request and export were done by on behalf of userspace, so
531	 * they may be undone on its behalf too.
532	 */
533	if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
534		gpiod_unexport(desc);
535		gpiod_free(desc);
536		status = 0;
537	}
538done:
539	if (status)
540		pr_debug("%s: status %d\n", __func__, status);
541	return status ? : len;
542}
543static CLASS_ATTR_WO(unexport);
544
545static struct attribute *gpio_class_attrs[] = {
546	&class_attr_export.attr,
547	&class_attr_unexport.attr,
548	NULL,
549};
550ATTRIBUTE_GROUPS(gpio_class);
551
552static struct class gpio_class = {
553	.name =		"gpio",
554	.class_groups = gpio_class_groups,
555};
556
557
558/**
559 * gpiod_export - export a GPIO through sysfs
560 * @desc: GPIO to make available, already requested
561 * @direction_may_change: true if userspace may change GPIO direction
562 * Context: arch_initcall or later
563 *
564 * When drivers want to make a GPIO accessible to userspace after they
565 * have requested it -- perhaps while debugging, or as part of their
566 * public interface -- they may use this routine.  If the GPIO can
567 * change direction (some can't) and the caller allows it, userspace
568 * will see "direction" sysfs attribute which may be used to change
569 * the gpio's direction.  A "value" attribute will always be provided.
570 *
571 * Returns zero on success, else an error.
572 */
573int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
574{
575	const char *ioname = NULL;
576	struct gpio_device *gdev;
577	struct gpiod_data *data;
578	struct device *dev;
579	int status, offset;
580
581	/* can't export until sysfs is available ... */
582	if (!class_is_registered(&gpio_class)) {
583		pr_debug("%s: called too early!\n", __func__);
584		return -ENOENT;
585	}
586
587	if (!desc) {
588		pr_debug("%s: invalid gpio descriptor\n", __func__);
589		return -EINVAL;
590	}
591
592	CLASS(gpio_chip_guard, guard)(desc);
593	if (!guard.gc)
594		return -ENODEV;
595
596	if (test_and_set_bit(FLAG_EXPORT, &desc->flags))
597		return -EPERM;
598
599	gdev = desc->gdev;
600
601	mutex_lock(&sysfs_lock);
602
603	/* check if chip is being removed */
604	if (!gdev->mockdev) {
605		status = -ENODEV;
606		goto err_unlock;
607	}
608
609	if (!test_bit(FLAG_REQUESTED, &desc->flags)) {
610		gpiod_dbg(desc, "%s: unavailable (not requested)\n", __func__);
611		status = -EPERM;
612		goto err_unlock;
613	}
614
615	data = kzalloc(sizeof(*data), GFP_KERNEL);
616	if (!data) {
617		status = -ENOMEM;
618		goto err_unlock;
619	}
620
621	data->desc = desc;
622	mutex_init(&data->mutex);
623	if (guard.gc->direction_input && guard.gc->direction_output)
624		data->direction_can_change = direction_may_change;
625	else
626		data->direction_can_change = false;
627
628	offset = gpio_chip_hwgpio(desc);
629	if (guard.gc->names && guard.gc->names[offset])
630		ioname = guard.gc->names[offset];
631
632	dev = device_create_with_groups(&gpio_class, &gdev->dev,
633					MKDEV(0, 0), data, gpio_groups,
634					ioname ? ioname : "gpio%u",
635					desc_to_gpio(desc));
636	if (IS_ERR(dev)) {
637		status = PTR_ERR(dev);
638		goto err_free_data;
639	}
640
641	mutex_unlock(&sysfs_lock);
642	return 0;
643
644err_free_data:
645	kfree(data);
646err_unlock:
647	mutex_unlock(&sysfs_lock);
648	clear_bit(FLAG_EXPORT, &desc->flags);
649	gpiod_dbg(desc, "%s: status %d\n", __func__, status);
650	return status;
651}
652EXPORT_SYMBOL_GPL(gpiod_export);
653
654static int match_export(struct device *dev, const void *desc)
655{
656	struct gpiod_data *data = dev_get_drvdata(dev);
657
658	return data->desc == desc;
659}
660
661/**
662 * gpiod_export_link - create a sysfs link to an exported GPIO node
663 * @dev: device under which to create symlink
664 * @name: name of the symlink
665 * @desc: GPIO to create symlink to, already exported
666 *
667 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
668 * node. Caller is responsible for unlinking.
669 *
670 * Returns zero on success, else an error.
671 */
672int gpiod_export_link(struct device *dev, const char *name,
673		      struct gpio_desc *desc)
674{
675	struct device *cdev;
676	int ret;
677
678	if (!desc) {
679		pr_warn("%s: invalid GPIO\n", __func__);
680		return -EINVAL;
681	}
682
683	cdev = class_find_device(&gpio_class, NULL, desc, match_export);
684	if (!cdev)
685		return -ENODEV;
686
687	ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
688	put_device(cdev);
689
690	return ret;
691}
692EXPORT_SYMBOL_GPL(gpiod_export_link);
693
694/**
695 * gpiod_unexport - reverse effect of gpiod_export()
696 * @desc: GPIO to make unavailable
697 *
698 * This is implicit on gpiod_free().
699 */
700void gpiod_unexport(struct gpio_desc *desc)
701{
702	struct gpiod_data *data;
703	struct device *dev;
704
705	if (!desc) {
706		pr_warn("%s: invalid GPIO\n", __func__);
707		return;
708	}
709
710	mutex_lock(&sysfs_lock);
711
712	if (!test_bit(FLAG_EXPORT, &desc->flags))
713		goto err_unlock;
714
715	dev = class_find_device(&gpio_class, NULL, desc, match_export);
716	if (!dev)
717		goto err_unlock;
718
719	data = dev_get_drvdata(dev);
720
721	clear_bit(FLAG_EXPORT, &desc->flags);
722
723	device_unregister(dev);
724
725	/*
726	 * Release irq after deregistration to prevent race with edge_store.
727	 */
728	if (data->irq_flags)
729		gpio_sysfs_free_irq(dev);
730
731	mutex_unlock(&sysfs_lock);
732
733	put_device(dev);
734	kfree(data);
735
736	return;
737
738err_unlock:
739	mutex_unlock(&sysfs_lock);
740}
741EXPORT_SYMBOL_GPL(gpiod_unexport);
742
743int gpiochip_sysfs_register(struct gpio_device *gdev)
744{
745	struct gpio_chip *chip;
746	struct device *parent;
747	struct device *dev;
748
749	/*
750	 * Many systems add gpio chips for SOC support very early,
751	 * before driver model support is available.  In those cases we
752	 * register later, in gpiolib_sysfs_init() ... here we just
753	 * verify that _some_ field of gpio_class got initialized.
754	 */
755	if (!class_is_registered(&gpio_class))
756		return 0;
757
758	guard(srcu)(&gdev->srcu);
759
760	chip = srcu_dereference(gdev->chip, &gdev->srcu);
761	if (!chip)
762		return -ENODEV;
763
764	/*
765	 * For sysfs backward compatibility we need to preserve this
766	 * preferred parenting to the gpio_chip parent field, if set.
767	 */
768	if (chip->parent)
769		parent = chip->parent;
770	else
771		parent = &gdev->dev;
772
773	/* use chip->base for the ID; it's already known to be unique */
774	dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), gdev,
775					gpiochip_groups, GPIOCHIP_NAME "%d",
776					chip->base);
777	if (IS_ERR(dev))
778		return PTR_ERR(dev);
779
780	mutex_lock(&sysfs_lock);
781	gdev->mockdev = dev;
782	mutex_unlock(&sysfs_lock);
783
784	return 0;
785}
786
787void gpiochip_sysfs_unregister(struct gpio_device *gdev)
788{
789	struct gpio_desc *desc;
790	struct gpio_chip *chip;
791
792	scoped_guard(mutex, &sysfs_lock) {
793		if (!gdev->mockdev)
794			return;
795
796		device_unregister(gdev->mockdev);
797
798		/* prevent further gpiod exports */
799		gdev->mockdev = NULL;
800	}
801
802	guard(srcu)(&gdev->srcu);
803
804	chip = srcu_dereference(gdev->chip, &gdev->srcu);
805	if (!chip)
806		return;
807
808	/* unregister gpiod class devices owned by sysfs */
809	for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) {
810		gpiod_unexport(desc);
811		gpiod_free(desc);
812	}
813}
814
815/*
816 * We're not really looking for a device - we just want to iterate over the
817 * list and call this callback for each GPIO device. This is why this function
818 * always returns 0.
819 */
820static int gpiofind_sysfs_register(struct gpio_chip *gc, const void *data)
821{
822	struct gpio_device *gdev = gc->gpiodev;
823	int ret;
824
825	if (gdev->mockdev)
826		return 0;
827
828	ret = gpiochip_sysfs_register(gdev);
829	if (ret)
830		chip_err(gc, "failed to register the sysfs entry: %d\n", ret);
831
832	return 0;
833}
834
835static int __init gpiolib_sysfs_init(void)
836{
837	int status;
838
839	status = class_register(&gpio_class);
840	if (status < 0)
841		return status;
842
843	/* Scan and register the gpio_chips which registered very
844	 * early (e.g. before the class_register above was called).
845	 *
846	 * We run before arch_initcall() so chip->dev nodes can have
847	 * registered, and so arch_initcall() can always gpiod_export().
848	 */
849	(void)gpio_device_find(NULL, gpiofind_sysfs_register);
850
851	return 0;
852}
853postcore_initcall(gpiolib_sysfs_init);
854