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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 unsigned int flags = data->irq_flags;
297 struct gpio_desc *desc = data->desc;
298 int status = 0;
299
300
301 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
302 return 0;
303
304 assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
305
306 /* reconfigure poll(2) support if enabled on one edge only */
307 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
308 flags == GPIO_IRQF_TRIGGER_RISING) {
309 gpio_sysfs_free_irq(dev);
310 status = gpio_sysfs_request_irq(dev, flags);
311 }
312
313 return status;
314}
315
316static ssize_t active_low_show(struct device *dev,
317 struct device_attribute *attr, char *buf)
318{
319 struct gpiod_data *data = dev_get_drvdata(dev);
320 struct gpio_desc *desc = data->desc;
321 int value;
322
323 mutex_lock(&data->mutex);
324
325 value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
326
327 mutex_unlock(&data->mutex);
328
329 return sysfs_emit(buf, "%d\n", value);
330}
331
332static ssize_t active_low_store(struct device *dev,
333 struct device_attribute *attr, const char *buf, size_t size)
334{
335 struct gpiod_data *data = dev_get_drvdata(dev);
336 ssize_t status;
337 long value;
338
339 status = kstrtol(buf, 0, &value);
340 if (status)
341 return status;
342
343 mutex_lock(&data->mutex);
344
345 status = gpio_sysfs_set_active_low(dev, value);
346
347 mutex_unlock(&data->mutex);
348
349 return status ? : size;
350}
351static DEVICE_ATTR_RW(active_low);
352
353static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
354 int n)
355{
356 struct device *dev = kobj_to_dev(kobj);
357 struct gpiod_data *data = dev_get_drvdata(dev);
358 struct gpio_desc *desc = data->desc;
359 umode_t mode = attr->mode;
360 bool show_direction = data->direction_can_change;
361
362 if (attr == &dev_attr_direction.attr) {
363 if (!show_direction)
364 mode = 0;
365 } else if (attr == &dev_attr_edge.attr) {
366 if (gpiod_to_irq(desc) < 0)
367 mode = 0;
368 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
369 mode = 0;
370 }
371
372 return mode;
373}
374
375static struct attribute *gpio_attrs[] = {
376 &dev_attr_direction.attr,
377 &dev_attr_edge.attr,
378 &dev_attr_value.attr,
379 &dev_attr_active_low.attr,
380 NULL,
381};
382
383static const struct attribute_group gpio_group = {
384 .attrs = gpio_attrs,
385 .is_visible = gpio_is_visible,
386};
387
388static const struct attribute_group *gpio_groups[] = {
389 &gpio_group,
390 NULL
391};
392
393/*
394 * /sys/class/gpio/gpiochipN/
395 * /base ... matching gpio_chip.base (N)
396 * /label ... matching gpio_chip.label
397 * /ngpio ... matching gpio_chip.ngpio
398 */
399
400static ssize_t base_show(struct device *dev,
401 struct device_attribute *attr, char *buf)
402{
403 const struct gpio_chip *chip = dev_get_drvdata(dev);
404
405 return sysfs_emit(buf, "%d\n", chip->base);
406}
407static DEVICE_ATTR_RO(base);
408
409static ssize_t label_show(struct device *dev,
410 struct device_attribute *attr, char *buf)
411{
412 const struct gpio_chip *chip = dev_get_drvdata(dev);
413
414 return sysfs_emit(buf, "%s\n", chip->label ?: "");
415}
416static DEVICE_ATTR_RO(label);
417
418static ssize_t ngpio_show(struct device *dev,
419 struct device_attribute *attr, char *buf)
420{
421 const struct gpio_chip *chip = dev_get_drvdata(dev);
422
423 return sysfs_emit(buf, "%u\n", chip->ngpio);
424}
425static DEVICE_ATTR_RO(ngpio);
426
427static struct attribute *gpiochip_attrs[] = {
428 &dev_attr_base.attr,
429 &dev_attr_label.attr,
430 &dev_attr_ngpio.attr,
431 NULL,
432};
433ATTRIBUTE_GROUPS(gpiochip);
434
435/*
436 * /sys/class/gpio/export ... write-only
437 * integer N ... number of GPIO to export (full access)
438 * /sys/class/gpio/unexport ... write-only
439 * integer N ... number of GPIO to unexport
440 */
441static ssize_t export_store(const struct class *class,
442 const struct class_attribute *attr,
443 const char *buf, size_t len)
444{
445 struct gpio_desc *desc;
446 struct gpio_chip *gc;
447 int status, offset;
448 long gpio;
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 struct gpio_desc *desc;
500 int status;
501 long gpio;
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 const char *ioname = NULL;
563 struct gpio_device *gdev;
564 struct gpiod_data *data;
565 struct gpio_chip *chip;
566 unsigned long flags;
567 struct device *dev;
568 int status, offset;
569
570 /* can't export until sysfs is available ... */
571 if (!class_is_registered(&gpio_class)) {
572 pr_debug("%s: called too early!\n", __func__);
573 return -ENOENT;
574 }
575
576 if (!desc) {
577 pr_debug("%s: invalid gpio descriptor\n", __func__);
578 return -EINVAL;
579 }
580
581 gdev = desc->gdev;
582 chip = gdev->chip;
583
584 mutex_lock(&sysfs_lock);
585
586 /* check if chip is being removed */
587 if (!chip || !gdev->mockdev) {
588 status = -ENODEV;
589 goto err_unlock;
590 }
591
592 spin_lock_irqsave(&gpio_lock, flags);
593 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
594 test_bit(FLAG_EXPORT, &desc->flags)) {
595 spin_unlock_irqrestore(&gpio_lock, flags);
596 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
597 __func__,
598 test_bit(FLAG_REQUESTED, &desc->flags),
599 test_bit(FLAG_EXPORT, &desc->flags));
600 status = -EPERM;
601 goto err_unlock;
602 }
603 spin_unlock_irqrestore(&gpio_lock, flags);
604
605 data = kzalloc(sizeof(*data), GFP_KERNEL);
606 if (!data) {
607 status = -ENOMEM;
608 goto err_unlock;
609 }
610
611 data->desc = desc;
612 mutex_init(&data->mutex);
613 if (chip->direction_input && chip->direction_output)
614 data->direction_can_change = direction_may_change;
615 else
616 data->direction_can_change = false;
617
618 offset = gpio_chip_hwgpio(desc);
619 if (chip->names && chip->names[offset])
620 ioname = chip->names[offset];
621
622 dev = device_create_with_groups(&gpio_class, &gdev->dev,
623 MKDEV(0, 0), data, gpio_groups,
624 ioname ? ioname : "gpio%u",
625 desc_to_gpio(desc));
626 if (IS_ERR(dev)) {
627 status = PTR_ERR(dev);
628 goto err_free_data;
629 }
630
631 set_bit(FLAG_EXPORT, &desc->flags);
632 mutex_unlock(&sysfs_lock);
633 return 0;
634
635err_free_data:
636 kfree(data);
637err_unlock:
638 mutex_unlock(&sysfs_lock);
639 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
640 return status;
641}
642EXPORT_SYMBOL_GPL(gpiod_export);
643
644static int match_export(struct device *dev, const void *desc)
645{
646 struct gpiod_data *data = dev_get_drvdata(dev);
647
648 return data->desc == desc;
649}
650
651/**
652 * gpiod_export_link - create a sysfs link to an exported GPIO node
653 * @dev: device under which to create symlink
654 * @name: name of the symlink
655 * @desc: GPIO to create symlink to, already exported
656 *
657 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
658 * node. Caller is responsible for unlinking.
659 *
660 * Returns zero on success, else an error.
661 */
662int gpiod_export_link(struct device *dev, const char *name,
663 struct gpio_desc *desc)
664{
665 struct device *cdev;
666 int ret;
667
668 if (!desc) {
669 pr_warn("%s: invalid GPIO\n", __func__);
670 return -EINVAL;
671 }
672
673 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
674 if (!cdev)
675 return -ENODEV;
676
677 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
678 put_device(cdev);
679
680 return ret;
681}
682EXPORT_SYMBOL_GPL(gpiod_export_link);
683
684/**
685 * gpiod_unexport - reverse effect of gpiod_export()
686 * @desc: GPIO to make unavailable
687 *
688 * This is implicit on gpiod_free().
689 */
690void gpiod_unexport(struct gpio_desc *desc)
691{
692 struct gpiod_data *data;
693 struct device *dev;
694
695 if (!desc) {
696 pr_warn("%s: invalid GPIO\n", __func__);
697 return;
698 }
699
700 mutex_lock(&sysfs_lock);
701
702 if (!test_bit(FLAG_EXPORT, &desc->flags))
703 goto err_unlock;
704
705 dev = class_find_device(&gpio_class, NULL, desc, match_export);
706 if (!dev)
707 goto err_unlock;
708
709 data = dev_get_drvdata(dev);
710
711 clear_bit(FLAG_EXPORT, &desc->flags);
712
713 device_unregister(dev);
714
715 /*
716 * Release irq after deregistration to prevent race with edge_store.
717 */
718 if (data->irq_flags)
719 gpio_sysfs_free_irq(dev);
720
721 mutex_unlock(&sysfs_lock);
722
723 put_device(dev);
724 kfree(data);
725
726 return;
727
728err_unlock:
729 mutex_unlock(&sysfs_lock);
730}
731EXPORT_SYMBOL_GPL(gpiod_unexport);
732
733int gpiochip_sysfs_register(struct gpio_device *gdev)
734{
735 struct gpio_chip *chip = gdev->chip;
736 struct device *parent;
737 struct device *dev;
738
739 /*
740 * Many systems add gpio chips for SOC support very early,
741 * before driver model support is available. In those cases we
742 * register later, in gpiolib_sysfs_init() ... here we just
743 * verify that _some_ field of gpio_class got initialized.
744 */
745 if (!class_is_registered(&gpio_class))
746 return 0;
747
748 /*
749 * For sysfs backward compatibility we need to preserve this
750 * preferred parenting to the gpio_chip parent field, if set.
751 */
752 if (chip->parent)
753 parent = chip->parent;
754 else
755 parent = &gdev->dev;
756
757 /* use chip->base for the ID; it's already known to be unique */
758 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
759 gpiochip_groups, GPIOCHIP_NAME "%d",
760 chip->base);
761 if (IS_ERR(dev))
762 return PTR_ERR(dev);
763
764 mutex_lock(&sysfs_lock);
765 gdev->mockdev = dev;
766 mutex_unlock(&sysfs_lock);
767
768 return 0;
769}
770
771void gpiochip_sysfs_unregister(struct gpio_device *gdev)
772{
773 struct gpio_desc *desc;
774 struct gpio_chip *chip = gdev->chip;
775
776 if (!gdev->mockdev)
777 return;
778
779 device_unregister(gdev->mockdev);
780
781 /* prevent further gpiod exports */
782 mutex_lock(&sysfs_lock);
783 gdev->mockdev = NULL;
784 mutex_unlock(&sysfs_lock);
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
793static int __init gpiolib_sysfs_init(void)
794{
795 int status;
796 unsigned long flags;
797 struct gpio_device *gdev;
798
799 status = class_register(&gpio_class);
800 if (status < 0)
801 return status;
802
803 /* Scan and register the gpio_chips which registered very
804 * early (e.g. before the class_register above was called).
805 *
806 * We run before arch_initcall() so chip->dev nodes can have
807 * registered, and so arch_initcall() can always gpiod_export().
808 */
809 spin_lock_irqsave(&gpio_lock, flags);
810 list_for_each_entry(gdev, &gpio_devices, list) {
811 if (gdev->mockdev)
812 continue;
813
814 /*
815 * TODO we yield gpio_lock here because
816 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
817 * and needs to be fixed.
818 *
819 * Also it would be nice to use gpio_device_find() here so we
820 * can keep gpio_chips local to gpiolib.c, but the yield of
821 * gpio_lock prevents us from doing this.
822 */
823 spin_unlock_irqrestore(&gpio_lock, flags);
824 status = gpiochip_sysfs_register(gdev);
825 spin_lock_irqsave(&gpio_lock, flags);
826 }
827 spin_unlock_irqrestore(&gpio_lock, flags);
828
829 return status;
830}
831postcore_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 "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, "%d\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);