1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/bitops.h>
4#include <linux/device.h>
5#include <linux/idr.h>
6#include <linux/init.h>
7#include <linux/interrupt.h>
8#include <linux/kdev_t.h>
9#include <linux/kstrtox.h>
10#include <linux/list.h>
11#include <linux/mutex.h>
12#include <linux/printk.h>
13#include <linux/slab.h>
14#include <linux/spinlock.h>
15#include <linux/string.h>
16#include <linux/sysfs.h>
17#include <linux/types.h>
18
19#include <linux/gpio/consumer.h>
20#include <linux/gpio/driver.h>
21
22#include "gpiolib.h"
23#include "gpiolib-sysfs.h"
24
25struct kernfs_node;
26
27#define GPIO_IRQF_TRIGGER_NONE		0
28#define GPIO_IRQF_TRIGGER_FALLING	BIT(0)
29#define GPIO_IRQF_TRIGGER_RISING	BIT(1)
30#define GPIO_IRQF_TRIGGER_BOTH		(GPIO_IRQF_TRIGGER_FALLING | \
31					 GPIO_IRQF_TRIGGER_RISING)
32
33struct gpiod_data {
34	struct gpio_desc *desc;
35
36	struct mutex mutex;
37	struct kernfs_node *value_kn;
38	int irq;
39	unsigned char irq_flags;
40
41	bool direction_can_change;
42};
43
44/*
45 * Lock to serialise gpiod export and unexport, and prevent re-export of
46 * gpiod whose chip is being unregistered.
47 */
48static DEFINE_MUTEX(sysfs_lock);
49
50/*
51 * /sys/class/gpio/gpioN... only for GPIOs that are exported
52 *   /direction
53 *      * MAY BE OMITTED if kernel won't allow direction changes
54 *      * is read/write as "in" or "out"
55 *      * may also be written as "high" or "low", initializing
56 *        output value as specified ("out" implies "low")
57 *   /value
58 *      * always readable, subject to hardware behavior
59 *      * may be writable, as zero/nonzero
60 *   /edge
61 *      * configures behavior of poll(2) on /value
62 *      * available only if pin can generate IRQs on input
63 *      * is read/write as "none", "falling", "rising", or "both"
64 *   /active_low
65 *      * configures polarity of /value
66 *      * is read/write as zero/nonzero
67 *      * also affects existing and subsequent "falling" and "rising"
68 *        /edge configuration
69 */
70
71static ssize_t direction_show(struct device *dev,
72		struct device_attribute *attr, char *buf)
73{
74	struct gpiod_data *data = dev_get_drvdata(dev);
75	struct gpio_desc *desc = data->desc;
76	int value;
77
78	mutex_lock(&data->mutex);
79
80	gpiod_get_direction(desc);
81	value = !!test_bit(FLAG_IS_OUT, &desc->flags);
82
83	mutex_unlock(&data->mutex);
84
85	return sysfs_emit(buf, "%s\n", value ? "out" : "in");
86}
87
88static ssize_t direction_store(struct device *dev,
89		struct device_attribute *attr, const char *buf, size_t size)
90{
91	struct gpiod_data *data = dev_get_drvdata(dev);
92	struct gpio_desc *desc = data->desc;
93	ssize_t			status;
94
95	mutex_lock(&data->mutex);
96
97	if (sysfs_streq(buf, "high"))
98		status = gpiod_direction_output_raw(desc, 1);
99	else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
100		status = gpiod_direction_output_raw(desc, 0);
101	else if (sysfs_streq(buf, "in"))
102		status = gpiod_direction_input(desc);
103	else
104		status = -EINVAL;
105
106	mutex_unlock(&data->mutex);
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	mutex_lock(&data->mutex);
120
121	status = gpiod_get_value_cansleep(desc);
122
123	mutex_unlock(&data->mutex);
124
125	if (status < 0)
126		return status;
127
128	return sysfs_emit(buf, "%zd\n", status);
129}
130
131static ssize_t value_store(struct device *dev,
132		struct device_attribute *attr, const char *buf, size_t size)
133{
134	struct gpiod_data *data = dev_get_drvdata(dev);
135	struct gpio_desc *desc = data->desc;
136	ssize_t status;
137	long value;
138
139	status = kstrtol(buf, 0, &value);
140
141	mutex_lock(&data->mutex);
142
143	if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
144		status = -EPERM;
145	} else if (status == 0) {
146		gpiod_set_value_cansleep(desc, value);
147		status = size;
148	}
149
150	mutex_unlock(&data->mutex);
151
152	return status;
153}
154static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
155
156static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
157{
158	struct gpiod_data *data = priv;
159
160	sysfs_notify_dirent(data->value_kn);
161
162	return IRQ_HANDLED;
163}
164
165/* Caller holds gpiod-data mutex. */
166static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
167{
168	struct gpiod_data	*data = dev_get_drvdata(dev);
169	struct gpio_desc	*desc = data->desc;
170	unsigned long		irq_flags;
171	int			ret;
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	if (flags & GPIO_IRQF_TRIGGER_RISING)
186		irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
187			IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
188
189	/*
190	 * FIXME: This should be done in the irq_request_resources callback
191	 *        when the irq is requested, but a few drivers currently fail
192	 *        to do so.
193	 *
194	 *        Remove this redundant call (along with the corresponding
195	 *        unlock) when those drivers have been fixed.
196	 */
197	ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
198	if (ret < 0)
199		goto err_put_kn;
200
201	ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
202				"gpiolib", data);
203	if (ret < 0)
204		goto err_unlock;
205
206	data->irq_flags = flags;
207
208	return 0;
209
210err_unlock:
211	gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
212err_put_kn:
213	sysfs_put(data->value_kn);
214
215	return ret;
216}
217
218/*
219 * Caller holds gpiod-data mutex (unless called after class-device
220 * deregistration).
221 */
222static void gpio_sysfs_free_irq(struct device *dev)
223{
224	struct gpiod_data *data = dev_get_drvdata(dev);
225	struct gpio_desc *desc = data->desc;
226
227	data->irq_flags = 0;
228	free_irq(data->irq, data);
229	gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
230	sysfs_put(data->value_kn);
231}
232
233static const char * const trigger_names[] = {
234	[GPIO_IRQF_TRIGGER_NONE]	= "none",
235	[GPIO_IRQF_TRIGGER_FALLING]	= "falling",
236	[GPIO_IRQF_TRIGGER_RISING]	= "rising",
237	[GPIO_IRQF_TRIGGER_BOTH]	= "both",
238};
239
240static ssize_t edge_show(struct device *dev,
241		struct device_attribute *attr, char *buf)
242{
243	struct gpiod_data *data = dev_get_drvdata(dev);
244	int flags;
245
246	mutex_lock(&data->mutex);
247
248	flags = data->irq_flags;
249
250	mutex_unlock(&data->mutex);
251
252	if (flags >= ARRAY_SIZE(trigger_names))
253		return 0;
254
255	return sysfs_emit(buf, "%s\n", trigger_names[flags]);
256}
257
258static ssize_t edge_store(struct device *dev,
259		struct device_attribute *attr, const char *buf, size_t size)
260{
261	struct gpiod_data *data = dev_get_drvdata(dev);
262	ssize_t	status = size;
263	int flags;
264
265	flags = sysfs_match_string(trigger_names, buf);
266	if (flags < 0)
267		return flags;
268
269	mutex_lock(&data->mutex);
270
271	if (flags == data->irq_flags) {
272		status = size;
273		goto out_unlock;
274	}
275
276	if (data->irq_flags)
277		gpio_sysfs_free_irq(dev);
278
279	if (flags) {
280		status = gpio_sysfs_request_irq(dev, flags);
281		if (!status)
282			status = size;
283	}
284
285out_unlock:
286	mutex_unlock(&data->mutex);
287
288	return status;
289}
290static DEVICE_ATTR_RW(edge);
291
292/* Caller holds gpiod-data mutex. */
293static int gpio_sysfs_set_active_low(struct device *dev, int value)
294{
295	struct gpiod_data	*data = dev_get_drvdata(dev);
296	struct gpio_desc	*desc = data->desc;
297	int			status = 0;
298	unsigned int		flags = data->irq_flags;
299
300	if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
301		return 0;
302
303	assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
304
305	/* reconfigure poll(2) support if enabled on one edge only */
306	if (flags == GPIO_IRQF_TRIGGER_FALLING ||
307					flags == GPIO_IRQF_TRIGGER_RISING) {
308		gpio_sysfs_free_irq(dev);
309		status = gpio_sysfs_request_irq(dev, flags);
310	}
311
312	return status;
313}
314
315static ssize_t active_low_show(struct device *dev,
316		struct device_attribute *attr, char *buf)
317{
318	struct gpiod_data *data = dev_get_drvdata(dev);
319	struct gpio_desc *desc = data->desc;
320	int value;
321
322	mutex_lock(&data->mutex);
323
324	value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
325
326	mutex_unlock(&data->mutex);
327
328	return sysfs_emit(buf, "%d\n", value);
329}
330
331static ssize_t active_low_store(struct device *dev,
332		struct device_attribute *attr, const char *buf, size_t size)
333{
334	struct gpiod_data	*data = dev_get_drvdata(dev);
335	ssize_t			status;
336	long			value;
337
338	status = kstrtol(buf, 0, &value);
339	if (status)
340		return status;
341
342	mutex_lock(&data->mutex);
343
344	status = gpio_sysfs_set_active_low(dev, value);
345
346	mutex_unlock(&data->mutex);
347
348	return status ? : size;
349}
350static DEVICE_ATTR_RW(active_low);
351
352static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
353			       int n)
354{
355	struct device *dev = kobj_to_dev(kobj);
356	struct gpiod_data *data = dev_get_drvdata(dev);
357	struct gpio_desc *desc = data->desc;
358	umode_t mode = attr->mode;
359	bool show_direction = data->direction_can_change;
360
361	if (attr == &dev_attr_direction.attr) {
362		if (!show_direction)
363			mode = 0;
364	} else if (attr == &dev_attr_edge.attr) {
365		if (gpiod_to_irq(desc) < 0)
366			mode = 0;
367		if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
368			mode = 0;
369	}
370
371	return mode;
372}
373
374static struct attribute *gpio_attrs[] = {
375	&dev_attr_direction.attr,
376	&dev_attr_edge.attr,
377	&dev_attr_value.attr,
378	&dev_attr_active_low.attr,
379	NULL,
380};
381
382static const struct attribute_group gpio_group = {
383	.attrs = gpio_attrs,
384	.is_visible = gpio_is_visible,
385};
386
387static const struct attribute_group *gpio_groups[] = {
388	&gpio_group,
389	NULL
390};
391
392/*
393 * /sys/class/gpio/gpiochipN/
394 *   /base ... matching gpio_chip.base (N)
395 *   /label ... matching gpio_chip.label
396 *   /ngpio ... matching gpio_chip.ngpio
397 */
398
399static ssize_t base_show(struct device *dev,
400			       struct device_attribute *attr, char *buf)
401{
402	const struct gpio_chip	*chip = dev_get_drvdata(dev);
403
404	return sysfs_emit(buf, "%d\n", chip->base);
405}
406static DEVICE_ATTR_RO(base);
407
408static ssize_t label_show(struct device *dev,
409			       struct device_attribute *attr, char *buf)
410{
411	const struct gpio_chip	*chip = dev_get_drvdata(dev);
412
413	return sysfs_emit(buf, "%s\n", chip->label ?: "");
414}
415static DEVICE_ATTR_RO(label);
416
417static ssize_t ngpio_show(struct device *dev,
418			       struct device_attribute *attr, char *buf)
419{
420	const struct gpio_chip	*chip = dev_get_drvdata(dev);
421
422	return sysfs_emit(buf, "%u\n", chip->ngpio);
423}
424static DEVICE_ATTR_RO(ngpio);
425
426static struct attribute *gpiochip_attrs[] = {
427	&dev_attr_base.attr,
428	&dev_attr_label.attr,
429	&dev_attr_ngpio.attr,
430	NULL,
431};
432ATTRIBUTE_GROUPS(gpiochip);
433
434/*
435 * /sys/class/gpio/export ... write-only
436 *	integer N ... number of GPIO to export (full access)
437 * /sys/class/gpio/unexport ... write-only
438 *	integer N ... number of GPIO to unexport
439 */
440static ssize_t export_store(const struct class *class,
441				const struct class_attribute *attr,
442				const char *buf, size_t len)
443{
444	long			gpio;
445	struct gpio_desc	*desc;
446	int			status;
447	struct gpio_chip	*gc;
448	int			offset;
449
450	status = kstrtol(buf, 0, &gpio);
451	if (status < 0)
452		goto done;
453
454	desc = gpio_to_desc(gpio);
455	/* reject invalid GPIOs */
456	if (!desc) {
457		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
458		return -EINVAL;
459	}
460	gc = desc->gdev->chip;
461	offset = gpio_chip_hwgpio(desc);
462	if (!gpiochip_line_is_valid(gc, offset)) {
463		pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
464		return -EINVAL;
465	}
466
467	/* No extra locking here; FLAG_SYSFS just signifies that the
468	 * request and export were done by on behalf of userspace, so
469	 * they may be undone on its behalf too.
470	 */
471
472	status = gpiod_request_user(desc, "sysfs");
473	if (status)
474		goto done;
475
476	status = gpiod_set_transitory(desc, false);
477	if (status) {
478		gpiod_free(desc);
479		goto done;
480	}
481
482	status = gpiod_export(desc, true);
483	if (status < 0)
484		gpiod_free(desc);
485	else
486		set_bit(FLAG_SYSFS, &desc->flags);
487
488done:
489	if (status)
490		pr_debug("%s: status %d\n", __func__, status);
491	return status ? : len;
492}
493static CLASS_ATTR_WO(export);
494
495static ssize_t unexport_store(const struct class *class,
496				const struct class_attribute *attr,
497				const char *buf, size_t len)
498{
499	long			gpio;
500	struct gpio_desc	*desc;
501	int			status;
502
503	status = kstrtol(buf, 0, &gpio);
504	if (status < 0)
505		goto done;
506
507	desc = gpio_to_desc(gpio);
508	/* reject bogus commands (gpiod_unexport() ignores them) */
509	if (!desc) {
510		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
511		return -EINVAL;
512	}
513
514	status = -EINVAL;
515
516	/* No extra locking here; FLAG_SYSFS just signifies that the
517	 * request and export were done by on behalf of userspace, so
518	 * they may be undone on its behalf too.
519	 */
520	if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
521		gpiod_unexport(desc);
522		gpiod_free(desc);
523		status = 0;
524	}
525done:
526	if (status)
527		pr_debug("%s: status %d\n", __func__, status);
528	return status ? : len;
529}
530static CLASS_ATTR_WO(unexport);
531
532static struct attribute *gpio_class_attrs[] = {
533	&class_attr_export.attr,
534	&class_attr_unexport.attr,
535	NULL,
536};
537ATTRIBUTE_GROUPS(gpio_class);
538
539static struct class gpio_class = {
540	.name =		"gpio",
541	.class_groups = gpio_class_groups,
542};
543
544
545/**
546 * gpiod_export - export a GPIO through sysfs
547 * @desc: GPIO to make available, already requested
548 * @direction_may_change: true if userspace may change GPIO direction
549 * Context: arch_initcall or later
550 *
551 * When drivers want to make a GPIO accessible to userspace after they
552 * have requested it -- perhaps while debugging, or as part of their
553 * public interface -- they may use this routine.  If the GPIO can
554 * change direction (some can't) and the caller allows it, userspace
555 * will see "direction" sysfs attribute which may be used to change
556 * the gpio's direction.  A "value" attribute will always be provided.
557 *
558 * Returns zero on success, else an error.
559 */
560int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
561{
562	struct gpio_chip	*chip;
563	struct gpio_device	*gdev;
564	struct gpiod_data	*data;
565	unsigned long		flags;
566	int			status;
567	const char		*ioname = NULL;
568	struct device		*dev;
569	int			offset;
570
571	/* can't export until sysfs is available ... */
572	if (!class_is_registered(&gpio_class)) {
573		pr_debug("%s: called too early!\n", __func__);
574		return -ENOENT;
575	}
576
577	if (!desc) {
578		pr_debug("%s: invalid gpio descriptor\n", __func__);
579		return -EINVAL;
580	}
581
582	gdev = desc->gdev;
583	chip = gdev->chip;
584
585	mutex_lock(&sysfs_lock);
586
587	/* check if chip is being removed */
588	if (!chip || !gdev->mockdev) {
589		status = -ENODEV;
590		goto err_unlock;
591	}
592
593	spin_lock_irqsave(&gpio_lock, flags);
594	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
595	     test_bit(FLAG_EXPORT, &desc->flags)) {
596		spin_unlock_irqrestore(&gpio_lock, flags);
597		gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
598				__func__,
599				test_bit(FLAG_REQUESTED, &desc->flags),
600				test_bit(FLAG_EXPORT, &desc->flags));
601		status = -EPERM;
602		goto err_unlock;
603	}
604	spin_unlock_irqrestore(&gpio_lock, flags);
605
606	data = kzalloc(sizeof(*data), GFP_KERNEL);
607	if (!data) {
608		status = -ENOMEM;
609		goto err_unlock;
610	}
611
612	data->desc = desc;
613	mutex_init(&data->mutex);
614	if (chip->direction_input && chip->direction_output)
615		data->direction_can_change = direction_may_change;
616	else
617		data->direction_can_change = false;
618
619	offset = gpio_chip_hwgpio(desc);
620	if (chip->names && chip->names[offset])
621		ioname = chip->names[offset];
622
623	dev = device_create_with_groups(&gpio_class, &gdev->dev,
624					MKDEV(0, 0), data, gpio_groups,
625					ioname ? ioname : "gpio%u",
626					desc_to_gpio(desc));
627	if (IS_ERR(dev)) {
628		status = PTR_ERR(dev);
629		goto err_free_data;
630	}
631
632	set_bit(FLAG_EXPORT, &desc->flags);
633	mutex_unlock(&sysfs_lock);
634	return 0;
635
636err_free_data:
637	kfree(data);
638err_unlock:
639	mutex_unlock(&sysfs_lock);
640	gpiod_dbg(desc, "%s: status %d\n", __func__, status);
641	return status;
642}
643EXPORT_SYMBOL_GPL(gpiod_export);
644
645static int match_export(struct device *dev, const void *desc)
646{
647	struct gpiod_data *data = dev_get_drvdata(dev);
648
649	return data->desc == desc;
650}
651
652/**
653 * gpiod_export_link - create a sysfs link to an exported GPIO node
654 * @dev: device under which to create symlink
655 * @name: name of the symlink
656 * @desc: GPIO to create symlink to, already exported
657 *
658 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
659 * node. Caller is responsible for unlinking.
660 *
661 * Returns zero on success, else an error.
662 */
663int gpiod_export_link(struct device *dev, const char *name,
664		      struct gpio_desc *desc)
665{
666	struct device *cdev;
667	int ret;
668
669	if (!desc) {
670		pr_warn("%s: invalid GPIO\n", __func__);
671		return -EINVAL;
672	}
673
674	cdev = class_find_device(&gpio_class, NULL, desc, match_export);
675	if (!cdev)
676		return -ENODEV;
677
678	ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
679	put_device(cdev);
680
681	return ret;
682}
683EXPORT_SYMBOL_GPL(gpiod_export_link);
684
685/**
686 * gpiod_unexport - reverse effect of gpiod_export()
687 * @desc: GPIO to make unavailable
688 *
689 * This is implicit on gpiod_free().
690 */
691void gpiod_unexport(struct gpio_desc *desc)
692{
693	struct gpiod_data *data;
694	struct device *dev;
695
696	if (!desc) {
697		pr_warn("%s: invalid GPIO\n", __func__);
698		return;
699	}
700
701	mutex_lock(&sysfs_lock);
702
703	if (!test_bit(FLAG_EXPORT, &desc->flags))
704		goto err_unlock;
705
706	dev = class_find_device(&gpio_class, NULL, desc, match_export);
707	if (!dev)
708		goto err_unlock;
709
710	data = dev_get_drvdata(dev);
711
712	clear_bit(FLAG_EXPORT, &desc->flags);
713
714	device_unregister(dev);
715
716	/*
717	 * Release irq after deregistration to prevent race with edge_store.
718	 */
719	if (data->irq_flags)
720		gpio_sysfs_free_irq(dev);
721
722	mutex_unlock(&sysfs_lock);
723
724	put_device(dev);
725	kfree(data);
726
727	return;
728
729err_unlock:
730	mutex_unlock(&sysfs_lock);
731}
732EXPORT_SYMBOL_GPL(gpiod_unexport);
733
734int gpiochip_sysfs_register(struct gpio_device *gdev)
735{
736	struct device	*dev;
737	struct device	*parent;
738	struct gpio_chip *chip = gdev->chip;
739
740	/*
741	 * Many systems add gpio chips for SOC support very early,
742	 * before driver model support is available.  In those cases we
743	 * register later, in gpiolib_sysfs_init() ... here we just
744	 * verify that _some_ field of gpio_class got initialized.
745	 */
746	if (!class_is_registered(&gpio_class))
747		return 0;
748
749	/*
750	 * For sysfs backward compatibility we need to preserve this
751	 * preferred parenting to the gpio_chip parent field, if set.
752	 */
753	if (chip->parent)
754		parent = chip->parent;
755	else
756		parent = &gdev->dev;
757
758	/* use chip->base for the ID; it's already known to be unique */
759	dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
760					gpiochip_groups, GPIOCHIP_NAME "%d",
761					chip->base);
762	if (IS_ERR(dev))
763		return PTR_ERR(dev);
764
765	mutex_lock(&sysfs_lock);
766	gdev->mockdev = dev;
767	mutex_unlock(&sysfs_lock);
768
769	return 0;
770}
771
772void gpiochip_sysfs_unregister(struct gpio_device *gdev)
773{
774	struct gpio_desc *desc;
775	struct gpio_chip *chip = gdev->chip;
776
777	if (!gdev->mockdev)
778		return;
779
780	device_unregister(gdev->mockdev);
781
782	/* prevent further gpiod exports */
783	mutex_lock(&sysfs_lock);
784	gdev->mockdev = NULL;
785	mutex_unlock(&sysfs_lock);
786
787	/* unregister gpiod class devices owned by sysfs */
788	for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) {
789		gpiod_unexport(desc);
790		gpiod_free(desc);
791	}
792}
793
794static int __init gpiolib_sysfs_init(void)
795{
796	int		status;
797	unsigned long	flags;
798	struct gpio_device *gdev;
799
800	status = class_register(&gpio_class);
801	if (status < 0)
802		return status;
803
804	/* Scan and register the gpio_chips which registered very
805	 * early (e.g. before the class_register above was called).
806	 *
807	 * We run before arch_initcall() so chip->dev nodes can have
808	 * registered, and so arch_initcall() can always gpiod_export().
809	 */
810	spin_lock_irqsave(&gpio_lock, flags);
811	list_for_each_entry(gdev, &gpio_devices, list) {
812		if (gdev->mockdev)
813			continue;
814
815		/*
816		 * TODO we yield gpio_lock here because
817		 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
818		 * and needs to be fixed.
819		 *
820		 * Also it would be nice to use gpio_device_find() here so we
821		 * can keep gpio_chips local to gpiolib.c, but the yield of
822		 * gpio_lock prevents us from doing this.
823		 */
824		spin_unlock_irqrestore(&gpio_lock, flags);
825		status = gpiochip_sysfs_register(gdev);
826		spin_lock_irqsave(&gpio_lock, flags);
827	}
828	spin_unlock_irqrestore(&gpio_lock, flags);
829
830	return status;
831}
832postcore_initcall(gpiolib_sysfs_init);
833