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1// SPDX-License-Identifier: GPL-2.0
2#include <linux/idr.h>
3#include <linux/mutex.h>
4#include <linux/device.h>
5#include <linux/sysfs.h>
6#include <linux/gpio/consumer.h>
7#include <linux/gpio/driver.h>
8#include <linux/interrupt.h>
9#include <linux/kdev_t.h>
10#include <linux/slab.h>
11#include <linux/ctype.h>
12
13#include "gpiolib.h"
14#include "gpiolib-sysfs.h"
15
16#define GPIO_IRQF_TRIGGER_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
462 status = kstrtol(buf, 0, &gpio);
463 if (status < 0)
464 goto done;
465
466 desc = gpio_to_desc(gpio);
467 /* reject invalid GPIOs */
468 if (!desc) {
469 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
470 return -EINVAL;
471 }
472
473 /* No extra locking here; FLAG_SYSFS just signifies that the
474 * request and export were done by on behalf of userspace, so
475 * they may be undone on its behalf too.
476 */
477
478 status = gpiod_request(desc, "sysfs");
479 if (status < 0) {
480 if (status == -EPROBE_DEFER)
481 status = -ENODEV;
482 goto done;
483 }
484
485 status = gpiod_set_transitory(desc, false);
486 if (!status) {
487 status = gpiod_export(desc, true);
488 if (status < 0)
489 gpiod_free(desc);
490 else
491 set_bit(FLAG_SYSFS, &desc->flags);
492 }
493
494done:
495 if (status)
496 pr_debug("%s: status %d\n", __func__, status);
497 return status ? : len;
498}
499static CLASS_ATTR_WO(export);
500
501static ssize_t unexport_store(struct class *class,
502 struct class_attribute *attr,
503 const char *buf, size_t len)
504{
505 long gpio;
506 struct gpio_desc *desc;
507 int status;
508
509 status = kstrtol(buf, 0, &gpio);
510 if (status < 0)
511 goto done;
512
513 desc = gpio_to_desc(gpio);
514 /* reject bogus commands (gpio_unexport ignores them) */
515 if (!desc) {
516 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
517 return -EINVAL;
518 }
519
520 status = -EINVAL;
521
522 /* No extra locking here; FLAG_SYSFS just signifies that the
523 * request and export were done by on behalf of userspace, so
524 * they may be undone on its behalf too.
525 */
526 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
527 status = 0;
528 gpiod_free(desc);
529 }
530done:
531 if (status)
532 pr_debug("%s: status %d\n", __func__, status);
533 return status ? : len;
534}
535static CLASS_ATTR_WO(unexport);
536
537static struct attribute *gpio_class_attrs[] = {
538 &class_attr_export.attr,
539 &class_attr_unexport.attr,
540 NULL,
541};
542ATTRIBUTE_GROUPS(gpio_class);
543
544static struct class gpio_class = {
545 .name = "gpio",
546 .owner = THIS_MODULE,
547
548 .class_groups = gpio_class_groups,
549};
550
551
552/**
553 * gpiod_export - export a GPIO through sysfs
554 * @desc: GPIO to make available, already requested
555 * @direction_may_change: true if userspace may change GPIO direction
556 * Context: arch_initcall or later
557 *
558 * When drivers want to make a GPIO accessible to userspace after they
559 * have requested it -- perhaps while debugging, or as part of their
560 * public interface -- they may use this routine. If the GPIO can
561 * change direction (some can't) and the caller allows it, userspace
562 * will see "direction" sysfs attribute which may be used to change
563 * the gpio's direction. A "value" attribute will always be provided.
564 *
565 * Returns zero on success, else an error.
566 */
567int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
568{
569 struct gpio_chip *chip;
570 struct gpio_device *gdev;
571 struct gpiod_data *data;
572 unsigned long flags;
573 int status;
574 const char *ioname = NULL;
575 struct device *dev;
576 int offset;
577
578 /* can't export until sysfs is available ... */
579 if (!gpio_class.p) {
580 pr_debug("%s: called too early!\n", __func__);
581 return -ENOENT;
582 }
583
584 if (!desc) {
585 pr_debug("%s: invalid gpio descriptor\n", __func__);
586 return -EINVAL;
587 }
588
589 gdev = desc->gdev;
590 chip = gdev->chip;
591
592 mutex_lock(&sysfs_lock);
593
594 /* check if chip is being removed */
595 if (!chip || !gdev->mockdev) {
596 status = -ENODEV;
597 goto err_unlock;
598 }
599
600 spin_lock_irqsave(&gpio_lock, flags);
601 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
602 test_bit(FLAG_EXPORT, &desc->flags)) {
603 spin_unlock_irqrestore(&gpio_lock, flags);
604 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
605 __func__,
606 test_bit(FLAG_REQUESTED, &desc->flags),
607 test_bit(FLAG_EXPORT, &desc->flags));
608 status = -EPERM;
609 goto err_unlock;
610 }
611 spin_unlock_irqrestore(&gpio_lock, flags);
612
613 data = kzalloc(sizeof(*data), GFP_KERNEL);
614 if (!data) {
615 status = -ENOMEM;
616 goto err_unlock;
617 }
618
619 data->desc = desc;
620 mutex_init(&data->mutex);
621 if (chip->direction_input && chip->direction_output)
622 data->direction_can_change = direction_may_change;
623 else
624 data->direction_can_change = false;
625
626 offset = gpio_chip_hwgpio(desc);
627 if (chip->names && chip->names[offset])
628 ioname = chip->names[offset];
629
630 dev = device_create_with_groups(&gpio_class, &gdev->dev,
631 MKDEV(0, 0), data, gpio_groups,
632 ioname ? ioname : "gpio%u",
633 desc_to_gpio(desc));
634 if (IS_ERR(dev)) {
635 status = PTR_ERR(dev);
636 goto err_free_data;
637 }
638
639 set_bit(FLAG_EXPORT, &desc->flags);
640 mutex_unlock(&sysfs_lock);
641 return 0;
642
643err_free_data:
644 kfree(data);
645err_unlock:
646 mutex_unlock(&sysfs_lock);
647 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
648 return status;
649}
650EXPORT_SYMBOL_GPL(gpiod_export);
651
652static int match_export(struct device *dev, const void *desc)
653{
654 struct gpiod_data *data = dev_get_drvdata(dev);
655
656 return data->desc == desc;
657}
658
659/**
660 * gpiod_export_link - create a sysfs link to an exported GPIO node
661 * @dev: device under which to create symlink
662 * @name: name of the symlink
663 * @desc: GPIO to create symlink to, already exported
664 *
665 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
666 * node. Caller is responsible for unlinking.
667 *
668 * Returns zero on success, else an error.
669 */
670int gpiod_export_link(struct device *dev, const char *name,
671 struct gpio_desc *desc)
672{
673 struct device *cdev;
674 int ret;
675
676 if (!desc) {
677 pr_warn("%s: invalid GPIO\n", __func__);
678 return -EINVAL;
679 }
680
681 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
682 if (!cdev)
683 return -ENODEV;
684
685 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
686 put_device(cdev);
687
688 return ret;
689}
690EXPORT_SYMBOL_GPL(gpiod_export_link);
691
692/**
693 * gpiod_unexport - reverse effect of gpiod_export()
694 * @desc: GPIO to make unavailable
695 *
696 * This is implicit on gpiod_free().
697 */
698void gpiod_unexport(struct gpio_desc *desc)
699{
700 struct gpiod_data *data;
701 struct device *dev;
702
703 if (!desc) {
704 pr_warn("%s: invalid GPIO\n", __func__);
705 return;
706 }
707
708 mutex_lock(&sysfs_lock);
709
710 if (!test_bit(FLAG_EXPORT, &desc->flags))
711 goto err_unlock;
712
713 dev = class_find_device(&gpio_class, NULL, desc, match_export);
714 if (!dev)
715 goto err_unlock;
716
717 data = dev_get_drvdata(dev);
718
719 clear_bit(FLAG_EXPORT, &desc->flags);
720
721 device_unregister(dev);
722
723 /*
724 * Release irq after deregistration to prevent race with edge_store.
725 */
726 if (data->irq_flags)
727 gpio_sysfs_free_irq(dev);
728
729 mutex_unlock(&sysfs_lock);
730
731 put_device(dev);
732 kfree(data);
733
734 return;
735
736err_unlock:
737 mutex_unlock(&sysfs_lock);
738}
739EXPORT_SYMBOL_GPL(gpiod_unexport);
740
741int gpiochip_sysfs_register(struct gpio_device *gdev)
742{
743 struct device *dev;
744 struct device *parent;
745 struct gpio_chip *chip = gdev->chip;
746
747 /*
748 * Many systems add gpio chips for SOC support very early,
749 * before driver model support is available. In those cases we
750 * register later, in gpiolib_sysfs_init() ... here we just
751 * verify that _some_ field of gpio_class got initialized.
752 */
753 if (!gpio_class.p)
754 return 0;
755
756 /*
757 * For sysfs backward compatibility we need to preserve this
758 * preferred parenting to the gpio_chip parent field, if set.
759 */
760 if (chip->parent)
761 parent = chip->parent;
762 else
763 parent = &gdev->dev;
764
765 /* use chip->base for the ID; it's already known to be unique */
766 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
767 gpiochip_groups, GPIOCHIP_NAME "%d",
768 chip->base);
769 if (IS_ERR(dev))
770 return PTR_ERR(dev);
771
772 mutex_lock(&sysfs_lock);
773 gdev->mockdev = dev;
774 mutex_unlock(&sysfs_lock);
775
776 return 0;
777}
778
779void gpiochip_sysfs_unregister(struct gpio_device *gdev)
780{
781 struct gpio_desc *desc;
782 struct gpio_chip *chip = gdev->chip;
783 unsigned int i;
784
785 if (!gdev->mockdev)
786 return;
787
788 device_unregister(gdev->mockdev);
789
790 /* prevent further gpiod exports */
791 mutex_lock(&sysfs_lock);
792 gdev->mockdev = NULL;
793 mutex_unlock(&sysfs_lock);
794
795 /* unregister gpiod class devices owned by sysfs */
796 for (i = 0; i < chip->ngpio; i++) {
797 desc = &gdev->descs[i];
798 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
799 gpiod_free(desc);
800 }
801}
802
803static int __init gpiolib_sysfs_init(void)
804{
805 int status;
806 unsigned long flags;
807 struct gpio_device *gdev;
808
809 status = class_register(&gpio_class);
810 if (status < 0)
811 return status;
812
813 /* Scan and register the gpio_chips which registered very
814 * early (e.g. before the class_register above was called).
815 *
816 * We run before arch_initcall() so chip->dev nodes can have
817 * registered, and so arch_initcall() can always gpio_export().
818 */
819 spin_lock_irqsave(&gpio_lock, flags);
820 list_for_each_entry(gdev, &gpio_devices, list) {
821 if (gdev->mockdev)
822 continue;
823
824 /*
825 * TODO we yield gpio_lock here because
826 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
827 * and needs to be fixed.
828 *
829 * Also it would be nice to use gpiochip_find() here so we
830 * can keep gpio_chips local to gpiolib.c, but the yield of
831 * gpio_lock prevents us from doing this.
832 */
833 spin_unlock_irqrestore(&gpio_lock, flags);
834 status = gpiochip_sysfs_register(gdev);
835 spin_lock_irqsave(&gpio_lock, flags);
836 }
837 spin_unlock_irqrestore(&gpio_lock, flags);
838
839 return status;
840}
841postcore_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);