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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);
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);