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