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