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1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/bitops.h>
4#include <linux/device.h>
5#include <linux/idr.h>
6#include <linux/init.h>
7#include <linux/interrupt.h>
8#include <linux/kdev_t.h>
9#include <linux/kstrtox.h>
10#include <linux/list.h>
11#include <linux/mutex.h>
12#include <linux/printk.h>
13#include <linux/slab.h>
14#include <linux/spinlock.h>
15#include <linux/string.h>
16#include <linux/sysfs.h>
17#include <linux/types.h>
18
19#include <linux/gpio/consumer.h>
20#include <linux/gpio/driver.h>
21
22#include "gpiolib.h"
23#include "gpiolib-sysfs.h"
24
25struct kernfs_node;
26
27#define GPIO_IRQF_TRIGGER_NONE 0
28#define GPIO_IRQF_TRIGGER_FALLING BIT(0)
29#define GPIO_IRQF_TRIGGER_RISING BIT(1)
30#define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
31 GPIO_IRQF_TRIGGER_RISING)
32
33struct gpiod_data {
34 struct gpio_desc *desc;
35
36 struct mutex mutex;
37 struct kernfs_node *value_kn;
38 int irq;
39 unsigned char irq_flags;
40
41 bool direction_can_change;
42};
43
44/*
45 * Lock to serialise gpiod export and unexport, and prevent re-export of
46 * gpiod whose chip is being unregistered.
47 */
48static DEFINE_MUTEX(sysfs_lock);
49
50/*
51 * /sys/class/gpio/gpioN... only for GPIOs that are exported
52 * /direction
53 * * MAY BE OMITTED if kernel won't allow direction changes
54 * * is read/write as "in" or "out"
55 * * may also be written as "high" or "low", initializing
56 * output value as specified ("out" implies "low")
57 * /value
58 * * always readable, subject to hardware behavior
59 * * may be writable, as zero/nonzero
60 * /edge
61 * * configures behavior of poll(2) on /value
62 * * available only if pin can generate IRQs on input
63 * * is read/write as "none", "falling", "rising", or "both"
64 * /active_low
65 * * configures polarity of /value
66 * * is read/write as zero/nonzero
67 * * also affects existing and subsequent "falling" and "rising"
68 * /edge configuration
69 */
70
71static ssize_t direction_show(struct device *dev,
72 struct device_attribute *attr, char *buf)
73{
74 struct gpiod_data *data = dev_get_drvdata(dev);
75 struct gpio_desc *desc = data->desc;
76 int value;
77
78 mutex_lock(&data->mutex);
79
80 gpiod_get_direction(desc);
81 value = !!test_bit(FLAG_IS_OUT, &desc->flags);
82
83 mutex_unlock(&data->mutex);
84
85 return sysfs_emit(buf, "%s\n", value ? "out" : "in");
86}
87
88static ssize_t direction_store(struct device *dev,
89 struct device_attribute *attr, const char *buf, size_t size)
90{
91 struct gpiod_data *data = dev_get_drvdata(dev);
92 struct gpio_desc *desc = data->desc;
93 ssize_t status;
94
95 mutex_lock(&data->mutex);
96
97 if (sysfs_streq(buf, "high"))
98 status = gpiod_direction_output_raw(desc, 1);
99 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
100 status = gpiod_direction_output_raw(desc, 0);
101 else if (sysfs_streq(buf, "in"))
102 status = gpiod_direction_input(desc);
103 else
104 status = -EINVAL;
105
106 mutex_unlock(&data->mutex);
107
108 return status ? : size;
109}
110static DEVICE_ATTR_RW(direction);
111
112static ssize_t value_show(struct device *dev,
113 struct device_attribute *attr, char *buf)
114{
115 struct gpiod_data *data = dev_get_drvdata(dev);
116 struct gpio_desc *desc = data->desc;
117 ssize_t status;
118
119 mutex_lock(&data->mutex);
120
121 status = gpiod_get_value_cansleep(desc);
122
123 mutex_unlock(&data->mutex);
124
125 if (status < 0)
126 return status;
127
128 return sysfs_emit(buf, "%zd\n", status);
129}
130
131static ssize_t value_store(struct device *dev,
132 struct device_attribute *attr, const char *buf, size_t size)
133{
134 struct gpiod_data *data = dev_get_drvdata(dev);
135 struct gpio_desc *desc = data->desc;
136 ssize_t status;
137 long value;
138
139 status = kstrtol(buf, 0, &value);
140
141 mutex_lock(&data->mutex);
142
143 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
144 status = -EPERM;
145 } else if (status == 0) {
146 gpiod_set_value_cansleep(desc, value);
147 status = size;
148 }
149
150 mutex_unlock(&data->mutex);
151
152 return status;
153}
154static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
155
156static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
157{
158 struct gpiod_data *data = priv;
159
160 sysfs_notify_dirent(data->value_kn);
161
162 return IRQ_HANDLED;
163}
164
165/* Caller holds gpiod-data mutex. */
166static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
167{
168 struct gpiod_data *data = dev_get_drvdata(dev);
169 struct gpio_desc *desc = data->desc;
170 unsigned long irq_flags;
171 int ret;
172
173 data->irq = gpiod_to_irq(desc);
174 if (data->irq < 0)
175 return -EIO;
176
177 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
178 if (!data->value_kn)
179 return -ENODEV;
180
181 irq_flags = IRQF_SHARED;
182 if (flags & GPIO_IRQF_TRIGGER_FALLING)
183 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
184 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
185 if (flags & GPIO_IRQF_TRIGGER_RISING)
186 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
187 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
188
189 /*
190 * FIXME: This should be done in the irq_request_resources callback
191 * when the irq is requested, but a few drivers currently fail
192 * to do so.
193 *
194 * Remove this redundant call (along with the corresponding
195 * unlock) when those drivers have been fixed.
196 */
197 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
198 if (ret < 0)
199 goto err_put_kn;
200
201 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
202 "gpiolib", data);
203 if (ret < 0)
204 goto err_unlock;
205
206 data->irq_flags = flags;
207
208 return 0;
209
210err_unlock:
211 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
212err_put_kn:
213 sysfs_put(data->value_kn);
214
215 return ret;
216}
217
218/*
219 * Caller holds gpiod-data mutex (unless called after class-device
220 * deregistration).
221 */
222static void gpio_sysfs_free_irq(struct device *dev)
223{
224 struct gpiod_data *data = dev_get_drvdata(dev);
225 struct gpio_desc *desc = data->desc;
226
227 data->irq_flags = 0;
228 free_irq(data->irq, data);
229 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
230 sysfs_put(data->value_kn);
231}
232
233static const char * const trigger_names[] = {
234 [GPIO_IRQF_TRIGGER_NONE] = "none",
235 [GPIO_IRQF_TRIGGER_FALLING] = "falling",
236 [GPIO_IRQF_TRIGGER_RISING] = "rising",
237 [GPIO_IRQF_TRIGGER_BOTH] = "both",
238};
239
240static ssize_t edge_show(struct device *dev,
241 struct device_attribute *attr, char *buf)
242{
243 struct gpiod_data *data = dev_get_drvdata(dev);
244 int flags;
245
246 mutex_lock(&data->mutex);
247
248 flags = data->irq_flags;
249
250 mutex_unlock(&data->mutex);
251
252 if (flags >= ARRAY_SIZE(trigger_names))
253 return 0;
254
255 return sysfs_emit(buf, "%s\n", trigger_names[flags]);
256}
257
258static ssize_t edge_store(struct device *dev,
259 struct device_attribute *attr, const char *buf, size_t size)
260{
261 struct gpiod_data *data = dev_get_drvdata(dev);
262 ssize_t status = size;
263 int flags;
264
265 flags = sysfs_match_string(trigger_names, buf);
266 if (flags < 0)
267 return flags;
268
269 mutex_lock(&data->mutex);
270
271 if (flags == data->irq_flags) {
272 status = size;
273 goto out_unlock;
274 }
275
276 if (data->irq_flags)
277 gpio_sysfs_free_irq(dev);
278
279 if (flags) {
280 status = gpio_sysfs_request_irq(dev, flags);
281 if (!status)
282 status = size;
283 }
284
285out_unlock:
286 mutex_unlock(&data->mutex);
287
288 return status;
289}
290static DEVICE_ATTR_RW(edge);
291
292/* Caller holds gpiod-data mutex. */
293static int gpio_sysfs_set_active_low(struct device *dev, int value)
294{
295 struct gpiod_data *data = dev_get_drvdata(dev);
296 unsigned int flags = data->irq_flags;
297 struct gpio_desc *desc = data->desc;
298 int status = 0;
299
300
301 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
302 return 0;
303
304 assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
305
306 /* reconfigure poll(2) support if enabled on one edge only */
307 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
308 flags == GPIO_IRQF_TRIGGER_RISING) {
309 gpio_sysfs_free_irq(dev);
310 status = gpio_sysfs_request_irq(dev, flags);
311 }
312
313 return status;
314}
315
316static ssize_t active_low_show(struct device *dev,
317 struct device_attribute *attr, char *buf)
318{
319 struct gpiod_data *data = dev_get_drvdata(dev);
320 struct gpio_desc *desc = data->desc;
321 int value;
322
323 mutex_lock(&data->mutex);
324
325 value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
326
327 mutex_unlock(&data->mutex);
328
329 return sysfs_emit(buf, "%d\n", value);
330}
331
332static ssize_t active_low_store(struct device *dev,
333 struct device_attribute *attr, const char *buf, size_t size)
334{
335 struct gpiod_data *data = dev_get_drvdata(dev);
336 ssize_t status;
337 long value;
338
339 status = kstrtol(buf, 0, &value);
340 if (status)
341 return status;
342
343 mutex_lock(&data->mutex);
344
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 = kobj_to_dev(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 sysfs_emit(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 sysfs_emit(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 sysfs_emit(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(const struct class *class,
442 const struct class_attribute *attr,
443 const char *buf, size_t len)
444{
445 struct gpio_desc *desc;
446 struct gpio_chip *gc;
447 int status, offset;
448 long gpio;
449
450 status = kstrtol(buf, 0, &gpio);
451 if (status < 0)
452 goto done;
453
454 desc = gpio_to_desc(gpio);
455 /* reject invalid GPIOs */
456 if (!desc) {
457 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
458 return -EINVAL;
459 }
460 gc = desc->gdev->chip;
461 offset = gpio_chip_hwgpio(desc);
462 if (!gpiochip_line_is_valid(gc, offset)) {
463 pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
464 return -EINVAL;
465 }
466
467 /* No extra locking here; FLAG_SYSFS just signifies that the
468 * request and export were done by on behalf of userspace, so
469 * they may be undone on its behalf too.
470 */
471
472 status = gpiod_request_user(desc, "sysfs");
473 if (status)
474 goto done;
475
476 status = gpiod_set_transitory(desc, false);
477 if (status) {
478 gpiod_free(desc);
479 goto done;
480 }
481
482 status = gpiod_export(desc, true);
483 if (status < 0)
484 gpiod_free(desc);
485 else
486 set_bit(FLAG_SYSFS, &desc->flags);
487
488done:
489 if (status)
490 pr_debug("%s: status %d\n", __func__, status);
491 return status ? : len;
492}
493static CLASS_ATTR_WO(export);
494
495static ssize_t unexport_store(const struct class *class,
496 const struct class_attribute *attr,
497 const char *buf, size_t len)
498{
499 struct gpio_desc *desc;
500 int status;
501 long gpio;
502
503 status = kstrtol(buf, 0, &gpio);
504 if (status < 0)
505 goto done;
506
507 desc = gpio_to_desc(gpio);
508 /* reject bogus commands (gpiod_unexport() ignores them) */
509 if (!desc) {
510 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
511 return -EINVAL;
512 }
513
514 status = -EINVAL;
515
516 /* No extra locking here; FLAG_SYSFS just signifies that the
517 * request and export were done by on behalf of userspace, so
518 * they may be undone on its behalf too.
519 */
520 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
521 gpiod_unexport(desc);
522 gpiod_free(desc);
523 status = 0;
524 }
525done:
526 if (status)
527 pr_debug("%s: status %d\n", __func__, status);
528 return status ? : len;
529}
530static CLASS_ATTR_WO(unexport);
531
532static struct attribute *gpio_class_attrs[] = {
533 &class_attr_export.attr,
534 &class_attr_unexport.attr,
535 NULL,
536};
537ATTRIBUTE_GROUPS(gpio_class);
538
539static struct class gpio_class = {
540 .name = "gpio",
541 .class_groups = gpio_class_groups,
542};
543
544
545/**
546 * gpiod_export - export a GPIO through sysfs
547 * @desc: GPIO to make available, already requested
548 * @direction_may_change: true if userspace may change GPIO direction
549 * Context: arch_initcall or later
550 *
551 * When drivers want to make a GPIO accessible to userspace after they
552 * have requested it -- perhaps while debugging, or as part of their
553 * public interface -- they may use this routine. If the GPIO can
554 * change direction (some can't) and the caller allows it, userspace
555 * will see "direction" sysfs attribute which may be used to change
556 * the gpio's direction. A "value" attribute will always be provided.
557 *
558 * Returns zero on success, else an error.
559 */
560int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
561{
562 const char *ioname = NULL;
563 struct gpio_device *gdev;
564 struct gpiod_data *data;
565 struct gpio_chip *chip;
566 unsigned long flags;
567 struct device *dev;
568 int status, offset;
569
570 /* can't export until sysfs is available ... */
571 if (!class_is_registered(&gpio_class)) {
572 pr_debug("%s: called too early!\n", __func__);
573 return -ENOENT;
574 }
575
576 if (!desc) {
577 pr_debug("%s: invalid gpio descriptor\n", __func__);
578 return -EINVAL;
579 }
580
581 gdev = desc->gdev;
582 chip = gdev->chip;
583
584 mutex_lock(&sysfs_lock);
585
586 /* check if chip is being removed */
587 if (!chip || !gdev->mockdev) {
588 status = -ENODEV;
589 goto err_unlock;
590 }
591
592 spin_lock_irqsave(&gpio_lock, flags);
593 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
594 test_bit(FLAG_EXPORT, &desc->flags)) {
595 spin_unlock_irqrestore(&gpio_lock, flags);
596 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
597 __func__,
598 test_bit(FLAG_REQUESTED, &desc->flags),
599 test_bit(FLAG_EXPORT, &desc->flags));
600 status = -EPERM;
601 goto err_unlock;
602 }
603 spin_unlock_irqrestore(&gpio_lock, flags);
604
605 data = kzalloc(sizeof(*data), GFP_KERNEL);
606 if (!data) {
607 status = -ENOMEM;
608 goto err_unlock;
609 }
610
611 data->desc = desc;
612 mutex_init(&data->mutex);
613 if (chip->direction_input && chip->direction_output)
614 data->direction_can_change = direction_may_change;
615 else
616 data->direction_can_change = false;
617
618 offset = gpio_chip_hwgpio(desc);
619 if (chip->names && chip->names[offset])
620 ioname = chip->names[offset];
621
622 dev = device_create_with_groups(&gpio_class, &gdev->dev,
623 MKDEV(0, 0), data, gpio_groups,
624 ioname ? ioname : "gpio%u",
625 desc_to_gpio(desc));
626 if (IS_ERR(dev)) {
627 status = PTR_ERR(dev);
628 goto err_free_data;
629 }
630
631 set_bit(FLAG_EXPORT, &desc->flags);
632 mutex_unlock(&sysfs_lock);
633 return 0;
634
635err_free_data:
636 kfree(data);
637err_unlock:
638 mutex_unlock(&sysfs_lock);
639 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
640 return status;
641}
642EXPORT_SYMBOL_GPL(gpiod_export);
643
644static int match_export(struct device *dev, const void *desc)
645{
646 struct gpiod_data *data = dev_get_drvdata(dev);
647
648 return data->desc == desc;
649}
650
651/**
652 * gpiod_export_link - create a sysfs link to an exported GPIO node
653 * @dev: device under which to create symlink
654 * @name: name of the symlink
655 * @desc: GPIO to create symlink to, already exported
656 *
657 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
658 * node. Caller is responsible for unlinking.
659 *
660 * Returns zero on success, else an error.
661 */
662int gpiod_export_link(struct device *dev, const char *name,
663 struct gpio_desc *desc)
664{
665 struct device *cdev;
666 int ret;
667
668 if (!desc) {
669 pr_warn("%s: invalid GPIO\n", __func__);
670 return -EINVAL;
671 }
672
673 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
674 if (!cdev)
675 return -ENODEV;
676
677 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
678 put_device(cdev);
679
680 return ret;
681}
682EXPORT_SYMBOL_GPL(gpiod_export_link);
683
684/**
685 * gpiod_unexport - reverse effect of gpiod_export()
686 * @desc: GPIO to make unavailable
687 *
688 * This is implicit on gpiod_free().
689 */
690void gpiod_unexport(struct gpio_desc *desc)
691{
692 struct gpiod_data *data;
693 struct device *dev;
694
695 if (!desc) {
696 pr_warn("%s: invalid GPIO\n", __func__);
697 return;
698 }
699
700 mutex_lock(&sysfs_lock);
701
702 if (!test_bit(FLAG_EXPORT, &desc->flags))
703 goto err_unlock;
704
705 dev = class_find_device(&gpio_class, NULL, desc, match_export);
706 if (!dev)
707 goto err_unlock;
708
709 data = dev_get_drvdata(dev);
710
711 clear_bit(FLAG_EXPORT, &desc->flags);
712
713 device_unregister(dev);
714
715 /*
716 * Release irq after deregistration to prevent race with edge_store.
717 */
718 if (data->irq_flags)
719 gpio_sysfs_free_irq(dev);
720
721 mutex_unlock(&sysfs_lock);
722
723 put_device(dev);
724 kfree(data);
725
726 return;
727
728err_unlock:
729 mutex_unlock(&sysfs_lock);
730}
731EXPORT_SYMBOL_GPL(gpiod_unexport);
732
733int gpiochip_sysfs_register(struct gpio_device *gdev)
734{
735 struct gpio_chip *chip = gdev->chip;
736 struct device *parent;
737 struct device *dev;
738
739 /*
740 * Many systems add gpio chips for SOC support very early,
741 * before driver model support is available. In those cases we
742 * register later, in gpiolib_sysfs_init() ... here we just
743 * verify that _some_ field of gpio_class got initialized.
744 */
745 if (!class_is_registered(&gpio_class))
746 return 0;
747
748 /*
749 * For sysfs backward compatibility we need to preserve this
750 * preferred parenting to the gpio_chip parent field, if set.
751 */
752 if (chip->parent)
753 parent = chip->parent;
754 else
755 parent = &gdev->dev;
756
757 /* use chip->base for the ID; it's already known to be unique */
758 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
759 gpiochip_groups, GPIOCHIP_NAME "%d",
760 chip->base);
761 if (IS_ERR(dev))
762 return PTR_ERR(dev);
763
764 mutex_lock(&sysfs_lock);
765 gdev->mockdev = dev;
766 mutex_unlock(&sysfs_lock);
767
768 return 0;
769}
770
771void gpiochip_sysfs_unregister(struct gpio_device *gdev)
772{
773 struct gpio_desc *desc;
774 struct gpio_chip *chip = gdev->chip;
775
776 if (!gdev->mockdev)
777 return;
778
779 device_unregister(gdev->mockdev);
780
781 /* prevent further gpiod exports */
782 mutex_lock(&sysfs_lock);
783 gdev->mockdev = NULL;
784 mutex_unlock(&sysfs_lock);
785
786 /* unregister gpiod class devices owned by sysfs */
787 for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) {
788 gpiod_unexport(desc);
789 gpiod_free(desc);
790 }
791}
792
793static int __init gpiolib_sysfs_init(void)
794{
795 int status;
796 unsigned long flags;
797 struct gpio_device *gdev;
798
799 status = class_register(&gpio_class);
800 if (status < 0)
801 return status;
802
803 /* Scan and register the gpio_chips which registered very
804 * early (e.g. before the class_register above was called).
805 *
806 * We run before arch_initcall() so chip->dev nodes can have
807 * registered, and so arch_initcall() can always gpiod_export().
808 */
809 spin_lock_irqsave(&gpio_lock, flags);
810 list_for_each_entry(gdev, &gpio_devices, list) {
811 if (gdev->mockdev)
812 continue;
813
814 /*
815 * TODO we yield gpio_lock here because
816 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
817 * and needs to be fixed.
818 *
819 * Also it would be nice to use gpio_device_find() here so we
820 * can keep gpio_chips local to gpiolib.c, but the yield of
821 * gpio_lock prevents us from doing this.
822 */
823 spin_unlock_irqrestore(&gpio_lock, flags);
824 status = gpiochip_sysfs_register(gdev);
825 spin_lock_irqsave(&gpio_lock, flags);
826 }
827 spin_unlock_irqrestore(&gpio_lock, flags);
828
829 return status;
830}
831postcore_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_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 = sysfs_emit(buf, "%s\n",
70 test_bit(FLAG_IS_OUT, &desc->flags) ? "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 status = sysfs_emit(buf, "%zd\n", status);
113
114 mutex_unlock(&data->mutex);
115
116 return status;
117}
118
119static ssize_t value_store(struct device *dev,
120 struct device_attribute *attr, const char *buf, size_t size)
121{
122 struct gpiod_data *data = dev_get_drvdata(dev);
123 struct gpio_desc *desc = data->desc;
124 ssize_t status = 0;
125
126 mutex_lock(&data->mutex);
127
128 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
129 status = -EPERM;
130 } else {
131 long value;
132
133 if (size <= 2 && isdigit(buf[0]) &&
134 (size == 1 || buf[1] == '\n'))
135 value = buf[0] - '0';
136 else
137 status = kstrtol(buf, 0, &value);
138 if (status == 0) {
139 gpiod_set_value_cansleep(desc, value);
140 status = size;
141 }
142 }
143
144 mutex_unlock(&data->mutex);
145
146 return status;
147}
148static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
149
150static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
151{
152 struct gpiod_data *data = priv;
153
154 sysfs_notify_dirent(data->value_kn);
155
156 return IRQ_HANDLED;
157}
158
159/* Caller holds gpiod-data mutex. */
160static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
161{
162 struct gpiod_data *data = dev_get_drvdata(dev);
163 struct gpio_desc *desc = data->desc;
164 unsigned long irq_flags;
165 int ret;
166
167 data->irq = gpiod_to_irq(desc);
168 if (data->irq < 0)
169 return -EIO;
170
171 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
172 if (!data->value_kn)
173 return -ENODEV;
174
175 irq_flags = IRQF_SHARED;
176 if (flags & GPIO_IRQF_TRIGGER_FALLING)
177 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
178 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
179 if (flags & GPIO_IRQF_TRIGGER_RISING)
180 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
181 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
182
183 /*
184 * FIXME: This should be done in the irq_request_resources callback
185 * when the irq is requested, but a few drivers currently fail
186 * to do so.
187 *
188 * Remove this redundant call (along with the corresponding
189 * unlock) when those drivers have been fixed.
190 */
191 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
192 if (ret < 0)
193 goto err_put_kn;
194
195 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
196 "gpiolib", data);
197 if (ret < 0)
198 goto err_unlock;
199
200 data->irq_flags = flags;
201
202 return 0;
203
204err_unlock:
205 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
206err_put_kn:
207 sysfs_put(data->value_kn);
208
209 return ret;
210}
211
212/*
213 * Caller holds gpiod-data mutex (unless called after class-device
214 * deregistration).
215 */
216static void gpio_sysfs_free_irq(struct device *dev)
217{
218 struct gpiod_data *data = dev_get_drvdata(dev);
219 struct gpio_desc *desc = data->desc;
220
221 data->irq_flags = 0;
222 free_irq(data->irq, data);
223 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
224 sysfs_put(data->value_kn);
225}
226
227static const struct {
228 const char *name;
229 unsigned char flags;
230} trigger_types[] = {
231 { "none", 0 },
232 { "falling", GPIO_IRQF_TRIGGER_FALLING },
233 { "rising", GPIO_IRQF_TRIGGER_RISING },
234 { "both", GPIO_IRQF_TRIGGER_BOTH },
235};
236
237static ssize_t edge_show(struct device *dev,
238 struct device_attribute *attr, char *buf)
239{
240 struct gpiod_data *data = dev_get_drvdata(dev);
241 ssize_t status = 0;
242 int i;
243
244 mutex_lock(&data->mutex);
245
246 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
247 if (data->irq_flags == trigger_types[i].flags)
248 break;
249 }
250 if (i < ARRAY_SIZE(trigger_types))
251 status = sysfs_emit(buf, "%s\n", trigger_types[i].name);
252
253 mutex_unlock(&data->mutex);
254
255 return status;
256}
257
258static ssize_t edge_store(struct device *dev,
259 struct device_attribute *attr, const char *buf, size_t size)
260{
261 struct gpiod_data *data = dev_get_drvdata(dev);
262 unsigned char flags;
263 ssize_t status = size;
264 int i;
265
266 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
267 if (sysfs_streq(trigger_types[i].name, buf))
268 break;
269 }
270
271 if (i == ARRAY_SIZE(trigger_types))
272 return -EINVAL;
273
274 flags = trigger_types[i].flags;
275
276 mutex_lock(&data->mutex);
277
278 if (flags == data->irq_flags) {
279 status = size;
280 goto out_unlock;
281 }
282
283 if (data->irq_flags)
284 gpio_sysfs_free_irq(dev);
285
286 if (flags) {
287 status = gpio_sysfs_request_irq(dev, flags);
288 if (!status)
289 status = size;
290 }
291
292out_unlock:
293 mutex_unlock(&data->mutex);
294
295 return status;
296}
297static DEVICE_ATTR_RW(edge);
298
299/* Caller holds gpiod-data mutex. */
300static int gpio_sysfs_set_active_low(struct device *dev, int value)
301{
302 struct gpiod_data *data = dev_get_drvdata(dev);
303 struct gpio_desc *desc = data->desc;
304 int status = 0;
305 unsigned int flags = data->irq_flags;
306
307 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
308 return 0;
309
310 assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
311
312 /* reconfigure poll(2) support if enabled on one edge only */
313 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
314 flags == GPIO_IRQF_TRIGGER_RISING) {
315 gpio_sysfs_free_irq(dev);
316 status = gpio_sysfs_request_irq(dev, flags);
317 }
318
319 return status;
320}
321
322static ssize_t active_low_show(struct device *dev,
323 struct device_attribute *attr, char *buf)
324{
325 struct gpiod_data *data = dev_get_drvdata(dev);
326 struct gpio_desc *desc = data->desc;
327 ssize_t status;
328
329 mutex_lock(&data->mutex);
330
331 status = sysfs_emit(buf, "%d\n",
332 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
333
334 mutex_unlock(&data->mutex);
335
336 return status;
337}
338
339static ssize_t active_low_store(struct device *dev,
340 struct device_attribute *attr, const char *buf, size_t size)
341{
342 struct gpiod_data *data = dev_get_drvdata(dev);
343 ssize_t status;
344 long value;
345
346 mutex_lock(&data->mutex);
347
348 status = kstrtol(buf, 0, &value);
349 if (status == 0)
350 status = gpio_sysfs_set_active_low(dev, value);
351
352 mutex_unlock(&data->mutex);
353
354 return status ? : size;
355}
356static DEVICE_ATTR_RW(active_low);
357
358static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
359 int n)
360{
361 struct device *dev = kobj_to_dev(kobj);
362 struct gpiod_data *data = dev_get_drvdata(dev);
363 struct gpio_desc *desc = data->desc;
364 umode_t mode = attr->mode;
365 bool show_direction = data->direction_can_change;
366
367 if (attr == &dev_attr_direction.attr) {
368 if (!show_direction)
369 mode = 0;
370 } else if (attr == &dev_attr_edge.attr) {
371 if (gpiod_to_irq(desc) < 0)
372 mode = 0;
373 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
374 mode = 0;
375 }
376
377 return mode;
378}
379
380static struct attribute *gpio_attrs[] = {
381 &dev_attr_direction.attr,
382 &dev_attr_edge.attr,
383 &dev_attr_value.attr,
384 &dev_attr_active_low.attr,
385 NULL,
386};
387
388static const struct attribute_group gpio_group = {
389 .attrs = gpio_attrs,
390 .is_visible = gpio_is_visible,
391};
392
393static const struct attribute_group *gpio_groups[] = {
394 &gpio_group,
395 NULL
396};
397
398/*
399 * /sys/class/gpio/gpiochipN/
400 * /base ... matching gpio_chip.base (N)
401 * /label ... matching gpio_chip.label
402 * /ngpio ... matching gpio_chip.ngpio
403 */
404
405static ssize_t base_show(struct device *dev,
406 struct device_attribute *attr, char *buf)
407{
408 const struct gpio_chip *chip = dev_get_drvdata(dev);
409
410 return sysfs_emit(buf, "%d\n", chip->base);
411}
412static DEVICE_ATTR_RO(base);
413
414static ssize_t label_show(struct device *dev,
415 struct device_attribute *attr, char *buf)
416{
417 const struct gpio_chip *chip = dev_get_drvdata(dev);
418
419 return sysfs_emit(buf, "%s\n", chip->label ?: "");
420}
421static DEVICE_ATTR_RO(label);
422
423static ssize_t ngpio_show(struct device *dev,
424 struct device_attribute *attr, char *buf)
425{
426 const struct gpio_chip *chip = dev_get_drvdata(dev);
427
428 return sysfs_emit(buf, "%u\n", chip->ngpio);
429}
430static DEVICE_ATTR_RO(ngpio);
431
432static struct attribute *gpiochip_attrs[] = {
433 &dev_attr_base.attr,
434 &dev_attr_label.attr,
435 &dev_attr_ngpio.attr,
436 NULL,
437};
438ATTRIBUTE_GROUPS(gpiochip);
439
440/*
441 * /sys/class/gpio/export ... write-only
442 * integer N ... number of GPIO to export (full access)
443 * /sys/class/gpio/unexport ... write-only
444 * integer N ... number of GPIO to unexport
445 */
446static ssize_t export_store(struct class *class,
447 struct class_attribute *attr,
448 const char *buf, size_t len)
449{
450 long gpio;
451 struct gpio_desc *desc;
452 int status;
453 struct gpio_chip *gc;
454 int offset;
455
456 status = kstrtol(buf, 0, &gpio);
457 if (status < 0)
458 goto done;
459
460 desc = gpio_to_desc(gpio);
461 /* reject invalid GPIOs */
462 if (!desc) {
463 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
464 return -EINVAL;
465 }
466 gc = desc->gdev->chip;
467 offset = gpio_chip_hwgpio(desc);
468 if (!gpiochip_line_is_valid(gc, offset)) {
469 pr_warn("%s: GPIO %ld masked\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) {
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);