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