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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#include <linux/idr.h>
2#include <linux/mutex.h>
3#include <linux/device.h>
4#include <linux/sysfs.h>
5#include <linux/gpio/consumer.h>
6#include <linux/gpio/driver.h>
7#include <linux/interrupt.h>
8#include <linux/kdev_t.h>
9#include <linux/slab.h>
10
11#include "gpiolib.h"
12
13#define GPIO_IRQF_TRIGGER_FALLING BIT(0)
14#define GPIO_IRQF_TRIGGER_RISING BIT(1)
15#define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
16 GPIO_IRQF_TRIGGER_RISING)
17
18struct gpiod_data {
19 struct gpio_desc *desc;
20
21 struct mutex mutex;
22 struct kernfs_node *value_kn;
23 int irq;
24 unsigned char irq_flags;
25
26 bool direction_can_change;
27};
28
29/*
30 * Lock to serialise gpiod export and unexport, and prevent re-export of
31 * gpiod whose chip is being unregistered.
32 */
33static DEFINE_MUTEX(sysfs_lock);
34
35/*
36 * /sys/class/gpio/gpioN... only for GPIOs that are exported
37 * /direction
38 * * MAY BE OMITTED if kernel won't allow direction changes
39 * * is read/write as "in" or "out"
40 * * may also be written as "high" or "low", initializing
41 * output value as specified ("out" implies "low")
42 * /value
43 * * always readable, subject to hardware behavior
44 * * may be writable, as zero/nonzero
45 * /edge
46 * * configures behavior of poll(2) on /value
47 * * available only if pin can generate IRQs on input
48 * * is read/write as "none", "falling", "rising", or "both"
49 * /active_low
50 * * configures polarity of /value
51 * * is read/write as zero/nonzero
52 * * also affects existing and subsequent "falling" and "rising"
53 * /edge configuration
54 */
55
56static ssize_t direction_show(struct device *dev,
57 struct device_attribute *attr, char *buf)
58{
59 struct gpiod_data *data = dev_get_drvdata(dev);
60 struct gpio_desc *desc = data->desc;
61 ssize_t status;
62
63 mutex_lock(&data->mutex);
64
65 gpiod_get_direction(desc);
66 status = sprintf(buf, "%s\n",
67 test_bit(FLAG_IS_OUT, &desc->flags)
68 ? "out" : "in");
69
70 mutex_unlock(&data->mutex);
71
72 return status;
73}
74
75static ssize_t direction_store(struct device *dev,
76 struct device_attribute *attr, const char *buf, size_t size)
77{
78 struct gpiod_data *data = dev_get_drvdata(dev);
79 struct gpio_desc *desc = data->desc;
80 ssize_t status;
81
82 mutex_lock(&data->mutex);
83
84 if (sysfs_streq(buf, "high"))
85 status = gpiod_direction_output_raw(desc, 1);
86 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
87 status = gpiod_direction_output_raw(desc, 0);
88 else if (sysfs_streq(buf, "in"))
89 status = gpiod_direction_input(desc);
90 else
91 status = -EINVAL;
92
93 mutex_unlock(&data->mutex);
94
95 return status ? : size;
96}
97static DEVICE_ATTR_RW(direction);
98
99static ssize_t value_show(struct device *dev,
100 struct device_attribute *attr, char *buf)
101{
102 struct gpiod_data *data = dev_get_drvdata(dev);
103 struct gpio_desc *desc = data->desc;
104 ssize_t status;
105
106 mutex_lock(&data->mutex);
107
108 status = sprintf(buf, "%d\n", gpiod_get_value_cansleep(desc));
109
110 mutex_unlock(&data->mutex);
111
112 return status;
113}
114
115static ssize_t value_store(struct device *dev,
116 struct device_attribute *attr, const char *buf, size_t size)
117{
118 struct gpiod_data *data = dev_get_drvdata(dev);
119 struct gpio_desc *desc = data->desc;
120 ssize_t status;
121
122 mutex_lock(&data->mutex);
123
124 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
125 status = -EPERM;
126 } else {
127 long value;
128
129 status = kstrtol(buf, 0, &value);
130 if (status == 0) {
131 gpiod_set_value_cansleep(desc, value);
132 status = size;
133 }
134 }
135
136 mutex_unlock(&data->mutex);
137
138 return status;
139}
140static DEVICE_ATTR_RW(value);
141
142static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
143{
144 struct gpiod_data *data = priv;
145
146 sysfs_notify_dirent(data->value_kn);
147
148 return IRQ_HANDLED;
149}
150
151/* Caller holds gpiod-data mutex. */
152static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
153{
154 struct gpiod_data *data = dev_get_drvdata(dev);
155 struct gpio_desc *desc = data->desc;
156 unsigned long irq_flags;
157 int ret;
158
159 data->irq = gpiod_to_irq(desc);
160 if (data->irq < 0)
161 return -EIO;
162
163 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
164 if (!data->value_kn)
165 return -ENODEV;
166
167 irq_flags = IRQF_SHARED;
168 if (flags & GPIO_IRQF_TRIGGER_FALLING)
169 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
170 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
171 if (flags & GPIO_IRQF_TRIGGER_RISING)
172 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
173 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
174
175 /*
176 * FIXME: This should be done in the irq_request_resources callback
177 * when the irq is requested, but a few drivers currently fail
178 * to do so.
179 *
180 * Remove this redundant call (along with the corresponding
181 * unlock) when those drivers have been fixed.
182 */
183 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
184 if (ret < 0)
185 goto err_put_kn;
186
187 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
188 "gpiolib", data);
189 if (ret < 0)
190 goto err_unlock;
191
192 data->irq_flags = flags;
193
194 return 0;
195
196err_unlock:
197 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
198err_put_kn:
199 sysfs_put(data->value_kn);
200
201 return ret;
202}
203
204/*
205 * Caller holds gpiod-data mutex (unless called after class-device
206 * deregistration).
207 */
208static void gpio_sysfs_free_irq(struct device *dev)
209{
210 struct gpiod_data *data = dev_get_drvdata(dev);
211 struct gpio_desc *desc = data->desc;
212
213 data->irq_flags = 0;
214 free_irq(data->irq, data);
215 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
216 sysfs_put(data->value_kn);
217}
218
219static const struct {
220 const char *name;
221 unsigned char flags;
222} trigger_types[] = {
223 { "none", 0 },
224 { "falling", GPIO_IRQF_TRIGGER_FALLING },
225 { "rising", GPIO_IRQF_TRIGGER_RISING },
226 { "both", GPIO_IRQF_TRIGGER_BOTH },
227};
228
229static ssize_t edge_show(struct device *dev,
230 struct device_attribute *attr, char *buf)
231{
232 struct gpiod_data *data = dev_get_drvdata(dev);
233 ssize_t status = 0;
234 int i;
235
236 mutex_lock(&data->mutex);
237
238 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
239 if (data->irq_flags == trigger_types[i].flags) {
240 status = sprintf(buf, "%s\n", trigger_types[i].name);
241 break;
242 }
243 }
244
245 mutex_unlock(&data->mutex);
246
247 return status;
248}
249
250static ssize_t edge_store(struct device *dev,
251 struct device_attribute *attr, const char *buf, size_t size)
252{
253 struct gpiod_data *data = dev_get_drvdata(dev);
254 unsigned char flags;
255 ssize_t status = size;
256 int i;
257
258 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
259 if (sysfs_streq(trigger_types[i].name, buf))
260 break;
261 }
262
263 if (i == ARRAY_SIZE(trigger_types))
264 return -EINVAL;
265
266 flags = trigger_types[i].flags;
267
268 mutex_lock(&data->mutex);
269
270 if (flags == data->irq_flags) {
271 status = size;
272 goto out_unlock;
273 }
274
275 if (data->irq_flags)
276 gpio_sysfs_free_irq(dev);
277
278 if (flags) {
279 status = gpio_sysfs_request_irq(dev, flags);
280 if (!status)
281 status = size;
282 }
283
284out_unlock:
285 mutex_unlock(&data->mutex);
286
287 return status;
288}
289static DEVICE_ATTR_RW(edge);
290
291/* Caller holds gpiod-data mutex. */
292static int gpio_sysfs_set_active_low(struct device *dev, int value)
293{
294 struct gpiod_data *data = dev_get_drvdata(dev);
295 struct gpio_desc *desc = data->desc;
296 int status = 0;
297 unsigned int flags = data->irq_flags;
298
299 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
300 return 0;
301
302 if (value)
303 set_bit(FLAG_ACTIVE_LOW, &desc->flags);
304 else
305 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
306
307 /* reconfigure poll(2) support if enabled on one edge only */
308 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
309 flags == GPIO_IRQF_TRIGGER_RISING) {
310 gpio_sysfs_free_irq(dev);
311 status = gpio_sysfs_request_irq(dev, flags);
312 }
313
314 return status;
315}
316
317static ssize_t active_low_show(struct device *dev,
318 struct device_attribute *attr, char *buf)
319{
320 struct gpiod_data *data = dev_get_drvdata(dev);
321 struct gpio_desc *desc = data->desc;
322 ssize_t status;
323
324 mutex_lock(&data->mutex);
325
326 status = sprintf(buf, "%d\n",
327 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
328
329 mutex_unlock(&data->mutex);
330
331 return status;
332}
333
334static ssize_t active_low_store(struct device *dev,
335 struct device_attribute *attr, const char *buf, size_t size)
336{
337 struct gpiod_data *data = dev_get_drvdata(dev);
338 ssize_t status;
339 long value;
340
341 mutex_lock(&data->mutex);
342
343 status = kstrtol(buf, 0, &value);
344 if (status == 0)
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 = container_of(kobj, struct device, 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 sprintf(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 sprintf(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 sprintf(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(struct class *class,
442 struct class_attribute *attr,
443 const char *buf, size_t len)
444{
445 long gpio;
446 struct gpio_desc *desc;
447 int status;
448
449 status = kstrtol(buf, 0, &gpio);
450 if (status < 0)
451 goto done;
452
453 desc = gpio_to_desc(gpio);
454 /* reject invalid GPIOs */
455 if (!desc) {
456 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
457 return -EINVAL;
458 }
459
460 /* No extra locking here; FLAG_SYSFS just signifies that the
461 * request and export were done by on behalf of userspace, so
462 * they may be undone on its behalf too.
463 */
464
465 status = gpiod_request(desc, "sysfs");
466 if (status < 0) {
467 if (status == -EPROBE_DEFER)
468 status = -ENODEV;
469 goto done;
470 }
471 status = gpiod_export(desc, true);
472 if (status < 0)
473 gpiod_free(desc);
474 else
475 set_bit(FLAG_SYSFS, &desc->flags);
476
477done:
478 if (status)
479 pr_debug("%s: status %d\n", __func__, status);
480 return status ? : len;
481}
482
483static ssize_t unexport_store(struct class *class,
484 struct class_attribute *attr,
485 const char *buf, size_t len)
486{
487 long gpio;
488 struct gpio_desc *desc;
489 int status;
490
491 status = kstrtol(buf, 0, &gpio);
492 if (status < 0)
493 goto done;
494
495 desc = gpio_to_desc(gpio);
496 /* reject bogus commands (gpio_unexport ignores them) */
497 if (!desc) {
498 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
499 return -EINVAL;
500 }
501
502 status = -EINVAL;
503
504 /* No extra locking here; FLAG_SYSFS just signifies that the
505 * request and export were done by on behalf of userspace, so
506 * they may be undone on its behalf too.
507 */
508 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
509 status = 0;
510 gpiod_free(desc);
511 }
512done:
513 if (status)
514 pr_debug("%s: status %d\n", __func__, status);
515 return status ? : len;
516}
517
518static struct class_attribute gpio_class_attrs[] = {
519 __ATTR(export, 0200, NULL, export_store),
520 __ATTR(unexport, 0200, NULL, unexport_store),
521 __ATTR_NULL,
522};
523
524static struct class gpio_class = {
525 .name = "gpio",
526 .owner = THIS_MODULE,
527
528 .class_attrs = gpio_class_attrs,
529};
530
531
532/**
533 * gpiod_export - export a GPIO through sysfs
534 * @gpio: gpio to make available, already requested
535 * @direction_may_change: true if userspace may change gpio direction
536 * Context: arch_initcall or later
537 *
538 * When drivers want to make a GPIO accessible to userspace after they
539 * have requested it -- perhaps while debugging, or as part of their
540 * public interface -- they may use this routine. If the GPIO can
541 * change direction (some can't) and the caller allows it, userspace
542 * will see "direction" sysfs attribute which may be used to change
543 * the gpio's direction. A "value" attribute will always be provided.
544 *
545 * Returns zero on success, else an error.
546 */
547int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
548{
549 struct gpio_chip *chip;
550 struct gpio_device *gdev;
551 struct gpiod_data *data;
552 unsigned long flags;
553 int status;
554 const char *ioname = NULL;
555 struct device *dev;
556 int offset;
557
558 /* can't export until sysfs is available ... */
559 if (!gpio_class.p) {
560 pr_debug("%s: called too early!\n", __func__);
561 return -ENOENT;
562 }
563
564 if (!desc) {
565 pr_debug("%s: invalid gpio descriptor\n", __func__);
566 return -EINVAL;
567 }
568
569 gdev = desc->gdev;
570 chip = gdev->chip;
571
572 mutex_lock(&sysfs_lock);
573
574 /* check if chip is being removed */
575 if (!chip || !gdev->mockdev) {
576 status = -ENODEV;
577 goto err_unlock;
578 }
579
580 spin_lock_irqsave(&gpio_lock, flags);
581 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
582 test_bit(FLAG_EXPORT, &desc->flags)) {
583 spin_unlock_irqrestore(&gpio_lock, flags);
584 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
585 __func__,
586 test_bit(FLAG_REQUESTED, &desc->flags),
587 test_bit(FLAG_EXPORT, &desc->flags));
588 status = -EPERM;
589 goto err_unlock;
590 }
591 spin_unlock_irqrestore(&gpio_lock, flags);
592
593 data = kzalloc(sizeof(*data), GFP_KERNEL);
594 if (!data) {
595 status = -ENOMEM;
596 goto err_unlock;
597 }
598
599 data->desc = desc;
600 mutex_init(&data->mutex);
601 if (chip->direction_input && chip->direction_output)
602 data->direction_can_change = direction_may_change;
603 else
604 data->direction_can_change = false;
605
606 offset = gpio_chip_hwgpio(desc);
607 if (chip->names && chip->names[offset])
608 ioname = chip->names[offset];
609
610 dev = device_create_with_groups(&gpio_class, &gdev->dev,
611 MKDEV(0, 0), data, gpio_groups,
612 ioname ? ioname : "gpio%u",
613 desc_to_gpio(desc));
614 if (IS_ERR(dev)) {
615 status = PTR_ERR(dev);
616 goto err_free_data;
617 }
618
619 set_bit(FLAG_EXPORT, &desc->flags);
620 mutex_unlock(&sysfs_lock);
621 return 0;
622
623err_free_data:
624 kfree(data);
625err_unlock:
626 mutex_unlock(&sysfs_lock);
627 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
628 return status;
629}
630EXPORT_SYMBOL_GPL(gpiod_export);
631
632static int match_export(struct device *dev, const void *desc)
633{
634 struct gpiod_data *data = dev_get_drvdata(dev);
635
636 return data->desc == desc;
637}
638
639/**
640 * gpiod_export_link - create a sysfs link to an exported GPIO node
641 * @dev: device under which to create symlink
642 * @name: name of the symlink
643 * @gpio: gpio to create symlink to, already exported
644 *
645 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
646 * node. Caller is responsible for unlinking.
647 *
648 * Returns zero on success, else an error.
649 */
650int gpiod_export_link(struct device *dev, const char *name,
651 struct gpio_desc *desc)
652{
653 struct device *cdev;
654 int ret;
655
656 if (!desc) {
657 pr_warn("%s: invalid GPIO\n", __func__);
658 return -EINVAL;
659 }
660
661 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
662 if (!cdev)
663 return -ENODEV;
664
665 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
666 put_device(cdev);
667
668 return ret;
669}
670EXPORT_SYMBOL_GPL(gpiod_export_link);
671
672/**
673 * gpiod_unexport - reverse effect of gpio_export()
674 * @gpio: gpio to make unavailable
675 *
676 * This is implicit on gpio_free().
677 */
678void gpiod_unexport(struct gpio_desc *desc)
679{
680 struct gpiod_data *data;
681 struct device *dev;
682
683 if (!desc) {
684 pr_warn("%s: invalid GPIO\n", __func__);
685 return;
686 }
687
688 mutex_lock(&sysfs_lock);
689
690 if (!test_bit(FLAG_EXPORT, &desc->flags))
691 goto err_unlock;
692
693 dev = class_find_device(&gpio_class, NULL, desc, match_export);
694 if (!dev)
695 goto err_unlock;
696
697 data = dev_get_drvdata(dev);
698
699 clear_bit(FLAG_EXPORT, &desc->flags);
700
701 device_unregister(dev);
702
703 /*
704 * Release irq after deregistration to prevent race with edge_store.
705 */
706 if (data->irq_flags)
707 gpio_sysfs_free_irq(dev);
708
709 mutex_unlock(&sysfs_lock);
710
711 put_device(dev);
712 kfree(data);
713
714 return;
715
716err_unlock:
717 mutex_unlock(&sysfs_lock);
718}
719EXPORT_SYMBOL_GPL(gpiod_unexport);
720
721int gpiochip_sysfs_register(struct gpio_device *gdev)
722{
723 struct device *dev;
724 struct device *parent;
725 struct gpio_chip *chip = gdev->chip;
726
727 /*
728 * Many systems add gpio chips for SOC support very early,
729 * before driver model support is available. In those cases we
730 * register later, in gpiolib_sysfs_init() ... here we just
731 * verify that _some_ field of gpio_class got initialized.
732 */
733 if (!gpio_class.p)
734 return 0;
735
736 /*
737 * For sysfs backward compatibility we need to preserve this
738 * preferred parenting to the gpio_chip parent field, if set.
739 */
740 if (chip->parent)
741 parent = chip->parent;
742 else
743 parent = &gdev->dev;
744
745 /* use chip->base for the ID; it's already known to be unique */
746 dev = device_create_with_groups(&gpio_class, parent,
747 MKDEV(0, 0),
748 chip, gpiochip_groups,
749 "gpiochip%d", chip->base);
750 if (IS_ERR(dev))
751 return PTR_ERR(dev);
752
753 mutex_lock(&sysfs_lock);
754 gdev->mockdev = dev;
755 mutex_unlock(&sysfs_lock);
756
757 return 0;
758}
759
760void gpiochip_sysfs_unregister(struct gpio_device *gdev)
761{
762 struct gpio_desc *desc;
763 struct gpio_chip *chip = gdev->chip;
764 unsigned int i;
765
766 if (!gdev->mockdev)
767 return;
768
769 device_unregister(gdev->mockdev);
770
771 /* prevent further gpiod exports */
772 mutex_lock(&sysfs_lock);
773 gdev->mockdev = NULL;
774 mutex_unlock(&sysfs_lock);
775
776 /* unregister gpiod class devices owned by sysfs */
777 for (i = 0; i < chip->ngpio; i++) {
778 desc = &gdev->descs[i];
779 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
780 gpiod_free(desc);
781 }
782}
783
784static int __init gpiolib_sysfs_init(void)
785{
786 int status;
787 unsigned long flags;
788 struct gpio_device *gdev;
789
790 status = class_register(&gpio_class);
791 if (status < 0)
792 return status;
793
794 /* Scan and register the gpio_chips which registered very
795 * early (e.g. before the class_register above was called).
796 *
797 * We run before arch_initcall() so chip->dev nodes can have
798 * registered, and so arch_initcall() can always gpio_export().
799 */
800 spin_lock_irqsave(&gpio_lock, flags);
801 list_for_each_entry(gdev, &gpio_devices, list) {
802 if (gdev->mockdev)
803 continue;
804
805 /*
806 * TODO we yield gpio_lock here because
807 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
808 * and needs to be fixed.
809 *
810 * Also it would be nice to use gpiochip_find() here so we
811 * can keep gpio_chips local to gpiolib.c, but the yield of
812 * gpio_lock prevents us from doing this.
813 */
814 spin_unlock_irqrestore(&gpio_lock, flags);
815 status = gpiochip_sysfs_register(gdev);
816 spin_lock_irqsave(&gpio_lock, flags);
817 }
818 spin_unlock_irqrestore(&gpio_lock, flags);
819
820 return status;
821}
822postcore_initcall(gpiolib_sysfs_init);