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1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/bitops.h>
4#include <linux/cleanup.h>
5#include <linux/device.h>
6#include <linux/idr.h>
7#include <linux/init.h>
8#include <linux/interrupt.h>
9#include <linux/kdev_t.h>
10#include <linux/kstrtox.h>
11#include <linux/list.h>
12#include <linux/mutex.h>
13#include <linux/printk.h>
14#include <linux/slab.h>
15#include <linux/spinlock.h>
16#include <linux/string.h>
17#include <linux/srcu.h>
18#include <linux/sysfs.h>
19#include <linux/types.h>
20
21#include <linux/gpio/consumer.h>
22#include <linux/gpio/driver.h>
23
24#include <uapi/linux/gpio.h>
25
26#include "gpiolib.h"
27#include "gpiolib-sysfs.h"
28
29struct kernfs_node;
30
31#define GPIO_IRQF_TRIGGER_NONE 0
32#define GPIO_IRQF_TRIGGER_FALLING BIT(0)
33#define GPIO_IRQF_TRIGGER_RISING BIT(1)
34#define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
35 GPIO_IRQF_TRIGGER_RISING)
36
37struct gpiod_data {
38 struct gpio_desc *desc;
39
40 struct mutex mutex;
41 struct kernfs_node *value_kn;
42 int irq;
43 unsigned char irq_flags;
44
45 bool direction_can_change;
46};
47
48/*
49 * Lock to serialise gpiod export and unexport, and prevent re-export of
50 * gpiod whose chip is being unregistered.
51 */
52static DEFINE_MUTEX(sysfs_lock);
53
54/*
55 * /sys/class/gpio/gpioN... only for GPIOs that are exported
56 * /direction
57 * * MAY BE OMITTED if kernel won't allow direction changes
58 * * is read/write as "in" or "out"
59 * * may also be written as "high" or "low", initializing
60 * output value as specified ("out" implies "low")
61 * /value
62 * * always readable, subject to hardware behavior
63 * * may be writable, as zero/nonzero
64 * /edge
65 * * configures behavior of poll(2) on /value
66 * * available only if pin can generate IRQs on input
67 * * is read/write as "none", "falling", "rising", or "both"
68 * /active_low
69 * * configures polarity of /value
70 * * is read/write as zero/nonzero
71 * * also affects existing and subsequent "falling" and "rising"
72 * /edge configuration
73 */
74
75static ssize_t direction_show(struct device *dev,
76 struct device_attribute *attr, char *buf)
77{
78 struct gpiod_data *data = dev_get_drvdata(dev);
79 struct gpio_desc *desc = data->desc;
80 int value;
81
82 scoped_guard(mutex, &data->mutex) {
83 gpiod_get_direction(desc);
84 value = !!test_bit(FLAG_IS_OUT, &desc->flags);
85 }
86
87 return sysfs_emit(buf, "%s\n", value ? "out" : "in");
88}
89
90static ssize_t direction_store(struct device *dev,
91 struct device_attribute *attr, const char *buf, size_t size)
92{
93 struct gpiod_data *data = dev_get_drvdata(dev);
94 struct gpio_desc *desc = data->desc;
95 ssize_t status;
96
97 guard(mutex)(&data->mutex);
98
99 if (sysfs_streq(buf, "high"))
100 status = gpiod_direction_output_raw(desc, 1);
101 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
102 status = gpiod_direction_output_raw(desc, 0);
103 else if (sysfs_streq(buf, "in"))
104 status = gpiod_direction_input(desc);
105 else
106 status = -EINVAL;
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 scoped_guard(mutex, &data->mutex)
120 status = gpiod_get_value_cansleep(desc);
121
122 if (status < 0)
123 return status;
124
125 return sysfs_emit(buf, "%zd\n", status);
126}
127
128static ssize_t value_store(struct device *dev,
129 struct device_attribute *attr, const char *buf, size_t size)
130{
131 struct gpiod_data *data = dev_get_drvdata(dev);
132 struct gpio_desc *desc = data->desc;
133 ssize_t status;
134 long value;
135
136 status = kstrtol(buf, 0, &value);
137
138 guard(mutex)(&data->mutex);
139
140 if (!test_bit(FLAG_IS_OUT, &desc->flags))
141 return -EPERM;
142
143 if (status)
144 return status;
145
146 gpiod_set_value_cansleep(desc, value);
147
148 return size;
149}
150static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
151
152static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
153{
154 struct gpiod_data *data = priv;
155
156 sysfs_notify_dirent(data->value_kn);
157
158 return IRQ_HANDLED;
159}
160
161/* Caller holds gpiod-data mutex. */
162static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
163{
164 struct gpiod_data *data = dev_get_drvdata(dev);
165 struct gpio_desc *desc = data->desc;
166 unsigned long irq_flags;
167 int ret;
168
169 CLASS(gpio_chip_guard, guard)(desc);
170 if (!guard.gc)
171 return -ENODEV;
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 set_bit(FLAG_EDGE_FALLING, &desc->flags);
186 }
187 if (flags & GPIO_IRQF_TRIGGER_RISING) {
188 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
189 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
190 set_bit(FLAG_EDGE_RISING, &desc->flags);
191 }
192
193 /*
194 * FIXME: This should be done in the irq_request_resources callback
195 * when the irq is requested, but a few drivers currently fail
196 * to do so.
197 *
198 * Remove this redundant call (along with the corresponding
199 * unlock) when those drivers have been fixed.
200 */
201 ret = gpiochip_lock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
202 if (ret < 0)
203 goto err_put_kn;
204
205 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
206 "gpiolib", data);
207 if (ret < 0)
208 goto err_unlock;
209
210 data->irq_flags = flags;
211
212 return 0;
213
214err_unlock:
215 gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
216err_put_kn:
217 clear_bit(FLAG_EDGE_RISING, &desc->flags);
218 clear_bit(FLAG_EDGE_FALLING, &desc->flags);
219 sysfs_put(data->value_kn);
220
221 return ret;
222}
223
224/*
225 * Caller holds gpiod-data mutex (unless called after class-device
226 * deregistration).
227 */
228static void gpio_sysfs_free_irq(struct device *dev)
229{
230 struct gpiod_data *data = dev_get_drvdata(dev);
231 struct gpio_desc *desc = data->desc;
232
233 CLASS(gpio_chip_guard, guard)(desc);
234 if (!guard.gc)
235 return;
236
237 data->irq_flags = 0;
238 free_irq(data->irq, data);
239 gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
240 clear_bit(FLAG_EDGE_RISING, &desc->flags);
241 clear_bit(FLAG_EDGE_FALLING, &desc->flags);
242 sysfs_put(data->value_kn);
243}
244
245static const char * const trigger_names[] = {
246 [GPIO_IRQF_TRIGGER_NONE] = "none",
247 [GPIO_IRQF_TRIGGER_FALLING] = "falling",
248 [GPIO_IRQF_TRIGGER_RISING] = "rising",
249 [GPIO_IRQF_TRIGGER_BOTH] = "both",
250};
251
252static ssize_t edge_show(struct device *dev,
253 struct device_attribute *attr, char *buf)
254{
255 struct gpiod_data *data = dev_get_drvdata(dev);
256 int flags;
257
258 scoped_guard(mutex, &data->mutex)
259 flags = data->irq_flags;
260
261 if (flags >= ARRAY_SIZE(trigger_names))
262 return 0;
263
264 return sysfs_emit(buf, "%s\n", trigger_names[flags]);
265}
266
267static ssize_t edge_store(struct device *dev,
268 struct device_attribute *attr, const char *buf, size_t size)
269{
270 struct gpiod_data *data = dev_get_drvdata(dev);
271 ssize_t status = size;
272 int flags;
273
274 flags = sysfs_match_string(trigger_names, buf);
275 if (flags < 0)
276 return flags;
277
278 guard(mutex)(&data->mutex);
279
280 if (flags == data->irq_flags)
281 return size;
282
283 if (data->irq_flags)
284 gpio_sysfs_free_irq(dev);
285
286 if (!flags)
287 return size;
288
289 status = gpio_sysfs_request_irq(dev, flags);
290 if (status)
291 return status;
292
293 gpiod_line_state_notify(data->desc, GPIO_V2_LINE_CHANGED_CONFIG);
294
295 return size;
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 unsigned int flags = data->irq_flags;
304 struct gpio_desc *desc = data->desc;
305 int status = 0;
306
307
308 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
309 return 0;
310
311 assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
312
313 /* reconfigure poll(2) support if enabled on one edge only */
314 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
315 flags == GPIO_IRQF_TRIGGER_RISING) {
316 gpio_sysfs_free_irq(dev);
317 status = gpio_sysfs_request_irq(dev, flags);
318 }
319
320 gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_CONFIG);
321
322 return status;
323}
324
325static ssize_t active_low_show(struct device *dev,
326 struct device_attribute *attr, char *buf)
327{
328 struct gpiod_data *data = dev_get_drvdata(dev);
329 struct gpio_desc *desc = data->desc;
330 int value;
331
332 scoped_guard(mutex, &data->mutex)
333 value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
334
335 return sysfs_emit(buf, "%d\n", value);
336}
337
338static ssize_t active_low_store(struct device *dev,
339 struct device_attribute *attr, const char *buf, size_t size)
340{
341 struct gpiod_data *data = dev_get_drvdata(dev);
342 ssize_t status;
343 long value;
344
345 status = kstrtol(buf, 0, &value);
346 if (status)
347 return status;
348
349 guard(mutex)(&data->mutex);
350
351 return gpio_sysfs_set_active_low(dev, value) ?: size;
352}
353static DEVICE_ATTR_RW(active_low);
354
355static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
356 int n)
357{
358 struct device *dev = kobj_to_dev(kobj);
359 struct gpiod_data *data = dev_get_drvdata(dev);
360 struct gpio_desc *desc = data->desc;
361 umode_t mode = attr->mode;
362 bool show_direction = data->direction_can_change;
363
364 if (attr == &dev_attr_direction.attr) {
365 if (!show_direction)
366 mode = 0;
367 } else if (attr == &dev_attr_edge.attr) {
368 if (gpiod_to_irq(desc) < 0)
369 mode = 0;
370 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
371 mode = 0;
372 }
373
374 return mode;
375}
376
377static struct attribute *gpio_attrs[] = {
378 &dev_attr_direction.attr,
379 &dev_attr_edge.attr,
380 &dev_attr_value.attr,
381 &dev_attr_active_low.attr,
382 NULL,
383};
384
385static const struct attribute_group gpio_group = {
386 .attrs = gpio_attrs,
387 .is_visible = gpio_is_visible,
388};
389
390static const struct attribute_group *gpio_groups[] = {
391 &gpio_group,
392 NULL
393};
394
395/*
396 * /sys/class/gpio/gpiochipN/
397 * /base ... matching gpio_chip.base (N)
398 * /label ... matching gpio_chip.label
399 * /ngpio ... matching gpio_chip.ngpio
400 */
401
402static ssize_t base_show(struct device *dev,
403 struct device_attribute *attr, char *buf)
404{
405 const struct gpio_device *gdev = dev_get_drvdata(dev);
406
407 return sysfs_emit(buf, "%u\n", gdev->base);
408}
409static DEVICE_ATTR_RO(base);
410
411static ssize_t label_show(struct device *dev,
412 struct device_attribute *attr, char *buf)
413{
414 const struct gpio_device *gdev = dev_get_drvdata(dev);
415
416 return sysfs_emit(buf, "%s\n", gdev->label);
417}
418static DEVICE_ATTR_RO(label);
419
420static ssize_t ngpio_show(struct device *dev,
421 struct device_attribute *attr, char *buf)
422{
423 const struct gpio_device *gdev = dev_get_drvdata(dev);
424
425 return sysfs_emit(buf, "%u\n", gdev->ngpio);
426}
427static DEVICE_ATTR_RO(ngpio);
428
429static struct attribute *gpiochip_attrs[] = {
430 &dev_attr_base.attr,
431 &dev_attr_label.attr,
432 &dev_attr_ngpio.attr,
433 NULL,
434};
435ATTRIBUTE_GROUPS(gpiochip);
436
437/*
438 * /sys/class/gpio/export ... write-only
439 * integer N ... number of GPIO to export (full access)
440 * /sys/class/gpio/unexport ... write-only
441 * integer N ... number of GPIO to unexport
442 */
443static ssize_t export_store(const struct class *class,
444 const struct class_attribute *attr,
445 const char *buf, size_t len)
446{
447 struct gpio_desc *desc;
448 int status, offset;
449 long gpio;
450
451 status = kstrtol(buf, 0, &gpio);
452 if (status)
453 return status;
454
455 desc = gpio_to_desc(gpio);
456 /* reject invalid GPIOs */
457 if (!desc) {
458 pr_debug_ratelimited("%s: invalid GPIO %ld\n", __func__, gpio);
459 return -EINVAL;
460 }
461
462 CLASS(gpio_chip_guard, guard)(desc);
463 if (!guard.gc)
464 return -ENODEV;
465
466 offset = gpio_chip_hwgpio(desc);
467 if (!gpiochip_line_is_valid(guard.gc, offset)) {
468 pr_debug_ratelimited("%s: GPIO %ld masked\n", __func__, gpio);
469 return -EINVAL;
470 }
471
472 /* No extra locking here; FLAG_SYSFS just signifies that the
473 * request and export were done by on behalf of userspace, so
474 * they may be undone on its behalf too.
475 */
476
477 status = gpiod_request_user(desc, "sysfs");
478 if (status)
479 goto done;
480
481 status = gpiod_set_transitory(desc, false);
482 if (status) {
483 gpiod_free(desc);
484 goto done;
485 }
486
487 status = gpiod_export(desc, true);
488 if (status < 0) {
489 gpiod_free(desc);
490 } else {
491 set_bit(FLAG_SYSFS, &desc->flags);
492 gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_REQUESTED);
493 }
494
495done:
496 if (status)
497 pr_debug("%s: status %d\n", __func__, status);
498 return status ? : len;
499}
500static CLASS_ATTR_WO(export);
501
502static ssize_t unexport_store(const struct class *class,
503 const struct class_attribute *attr,
504 const char *buf, size_t len)
505{
506 struct gpio_desc *desc;
507 int status;
508 long gpio;
509
510 status = kstrtol(buf, 0, &gpio);
511 if (status < 0)
512 goto done;
513
514 desc = gpio_to_desc(gpio);
515 /* reject bogus commands (gpiod_unexport() ignores them) */
516 if (!desc) {
517 pr_debug_ratelimited("%s: invalid GPIO %ld\n", __func__, gpio);
518 return -EINVAL;
519 }
520
521 status = -EINVAL;
522
523 /* No extra locking here; FLAG_SYSFS just signifies that the
524 * request and export were done by on behalf of userspace, so
525 * they may be undone on its behalf too.
526 */
527 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
528 gpiod_unexport(desc);
529 gpiod_free(desc);
530 status = 0;
531 }
532done:
533 if (status)
534 pr_debug("%s: status %d\n", __func__, status);
535 return status ? : len;
536}
537static CLASS_ATTR_WO(unexport);
538
539static struct attribute *gpio_class_attrs[] = {
540 &class_attr_export.attr,
541 &class_attr_unexport.attr,
542 NULL,
543};
544ATTRIBUTE_GROUPS(gpio_class);
545
546static const struct class gpio_class = {
547 .name = "gpio",
548 .class_groups = gpio_class_groups,
549};
550
551/**
552 * gpiod_export - export a GPIO through sysfs
553 * @desc: GPIO to make available, already requested
554 * @direction_may_change: true if userspace may change GPIO direction
555 * Context: arch_initcall or later
556 *
557 * When drivers want to make a GPIO accessible to userspace after they
558 * have requested it -- perhaps while debugging, or as part of their
559 * public interface -- they may use this routine. If the GPIO can
560 * change direction (some can't) and the caller allows it, userspace
561 * will see "direction" sysfs attribute which may be used to change
562 * the gpio's direction. A "value" attribute will always be provided.
563 *
564 * Returns:
565 * 0 on success, or negative errno on failure.
566 */
567int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
568{
569 struct gpio_device *gdev;
570 struct gpiod_data *data;
571 struct device *dev;
572 int status;
573
574 /* can't export until sysfs is available ... */
575 if (!class_is_registered(&gpio_class)) {
576 pr_debug("%s: called too early!\n", __func__);
577 return -ENOENT;
578 }
579
580 if (!desc) {
581 pr_debug("%s: invalid gpio descriptor\n", __func__);
582 return -EINVAL;
583 }
584
585 CLASS(gpio_chip_guard, guard)(desc);
586 if (!guard.gc)
587 return -ENODEV;
588
589 if (test_and_set_bit(FLAG_EXPORT, &desc->flags))
590 return -EPERM;
591
592 gdev = desc->gdev;
593
594 guard(mutex)(&sysfs_lock);
595
596 /* check if chip is being removed */
597 if (!gdev->mockdev) {
598 status = -ENODEV;
599 goto err_clear_bit;
600 }
601
602 if (!test_bit(FLAG_REQUESTED, &desc->flags)) {
603 gpiod_dbg(desc, "%s: unavailable (not requested)\n", __func__);
604 status = -EPERM;
605 goto err_clear_bit;
606 }
607
608 data = kzalloc(sizeof(*data), GFP_KERNEL);
609 if (!data) {
610 status = -ENOMEM;
611 goto err_clear_bit;
612 }
613
614 data->desc = desc;
615 mutex_init(&data->mutex);
616 if (guard.gc->direction_input && guard.gc->direction_output)
617 data->direction_can_change = direction_may_change;
618 else
619 data->direction_can_change = false;
620
621 dev = device_create_with_groups(&gpio_class, &gdev->dev,
622 MKDEV(0, 0), data, gpio_groups,
623 "gpio%u", desc_to_gpio(desc));
624 if (IS_ERR(dev)) {
625 status = PTR_ERR(dev);
626 goto err_free_data;
627 }
628
629 return 0;
630
631err_free_data:
632 kfree(data);
633err_clear_bit:
634 clear_bit(FLAG_EXPORT, &desc->flags);
635 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
636 return status;
637}
638EXPORT_SYMBOL_GPL(gpiod_export);
639
640static int match_export(struct device *dev, const void *desc)
641{
642 struct gpiod_data *data = dev_get_drvdata(dev);
643
644 return data->desc == desc;
645}
646
647/**
648 * gpiod_export_link - create a sysfs link to an exported GPIO node
649 * @dev: device under which to create symlink
650 * @name: name of the symlink
651 * @desc: GPIO to create symlink to, already exported
652 *
653 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
654 * node. Caller is responsible for unlinking.
655 *
656 * Returns:
657 * 0 on success, or negative errno on failure.
658 */
659int gpiod_export_link(struct device *dev, const char *name,
660 struct gpio_desc *desc)
661{
662 struct device *cdev;
663 int ret;
664
665 if (!desc) {
666 pr_warn("%s: invalid GPIO\n", __func__);
667 return -EINVAL;
668 }
669
670 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
671 if (!cdev)
672 return -ENODEV;
673
674 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
675 put_device(cdev);
676
677 return ret;
678}
679EXPORT_SYMBOL_GPL(gpiod_export_link);
680
681/**
682 * gpiod_unexport - reverse effect of gpiod_export()
683 * @desc: GPIO to make unavailable
684 *
685 * This is implicit on gpiod_free().
686 */
687void gpiod_unexport(struct gpio_desc *desc)
688{
689 struct gpiod_data *data;
690 struct device *dev;
691
692 if (!desc) {
693 pr_warn("%s: invalid GPIO\n", __func__);
694 return;
695 }
696
697 scoped_guard(mutex, &sysfs_lock) {
698 if (!test_bit(FLAG_EXPORT, &desc->flags))
699 return;
700
701 dev = class_find_device(&gpio_class, NULL, desc, match_export);
702 if (!dev)
703 return;
704
705 data = dev_get_drvdata(dev);
706 clear_bit(FLAG_EXPORT, &desc->flags);
707 device_unregister(dev);
708
709 /*
710 * Release irq after deregistration to prevent race with
711 * edge_store.
712 */
713 if (data->irq_flags)
714 gpio_sysfs_free_irq(dev);
715 }
716
717 put_device(dev);
718 kfree(data);
719}
720EXPORT_SYMBOL_GPL(gpiod_unexport);
721
722int gpiochip_sysfs_register(struct gpio_device *gdev)
723{
724 struct gpio_chip *chip;
725 struct device *parent;
726 struct device *dev;
727
728 /*
729 * Many systems add gpio chips for SOC support very early,
730 * before driver model support is available. In those cases we
731 * register later, in gpiolib_sysfs_init() ... here we just
732 * verify that _some_ field of gpio_class got initialized.
733 */
734 if (!class_is_registered(&gpio_class))
735 return 0;
736
737 guard(srcu)(&gdev->srcu);
738
739 chip = srcu_dereference(gdev->chip, &gdev->srcu);
740 if (!chip)
741 return -ENODEV;
742
743 /*
744 * For sysfs backward compatibility we need to preserve this
745 * preferred parenting to the gpio_chip parent field, if set.
746 */
747 if (chip->parent)
748 parent = chip->parent;
749 else
750 parent = &gdev->dev;
751
752 /* use chip->base for the ID; it's already known to be unique */
753 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), gdev,
754 gpiochip_groups, GPIOCHIP_NAME "%d",
755 chip->base);
756 if (IS_ERR(dev))
757 return PTR_ERR(dev);
758
759 guard(mutex)(&sysfs_lock);
760 gdev->mockdev = dev;
761
762 return 0;
763}
764
765void gpiochip_sysfs_unregister(struct gpio_device *gdev)
766{
767 struct gpio_desc *desc;
768 struct gpio_chip *chip;
769
770 scoped_guard(mutex, &sysfs_lock) {
771 if (!gdev->mockdev)
772 return;
773
774 device_unregister(gdev->mockdev);
775
776 /* prevent further gpiod exports */
777 gdev->mockdev = NULL;
778 }
779
780 guard(srcu)(&gdev->srcu);
781
782 chip = srcu_dereference(gdev->chip, &gdev->srcu);
783 if (!chip)
784 return;
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
793/*
794 * We're not really looking for a device - we just want to iterate over the
795 * list and call this callback for each GPIO device. This is why this function
796 * always returns 0.
797 */
798static int gpiofind_sysfs_register(struct gpio_chip *gc, const void *data)
799{
800 struct gpio_device *gdev = gc->gpiodev;
801 int ret;
802
803 if (gdev->mockdev)
804 return 0;
805
806 ret = gpiochip_sysfs_register(gdev);
807 if (ret)
808 chip_err(gc, "failed to register the sysfs entry: %d\n", ret);
809
810 return 0;
811}
812
813static int __init gpiolib_sysfs_init(void)
814{
815 int status;
816
817 status = class_register(&gpio_class);
818 if (status < 0)
819 return status;
820
821 /* Scan and register the gpio_chips which registered very
822 * early (e.g. before the class_register above was called).
823 *
824 * We run before arch_initcall() so chip->dev nodes can have
825 * registered, and so arch_initcall() can always gpiod_export().
826 */
827 (void)gpio_device_find(NULL, gpiofind_sysfs_register);
828
829 return 0;
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
15#define GPIO_IRQF_TRIGGER_FALLING BIT(0)
16#define GPIO_IRQF_TRIGGER_RISING BIT(1)
17#define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
18 GPIO_IRQF_TRIGGER_RISING)
19
20struct gpiod_data {
21 struct gpio_desc *desc;
22
23 struct mutex mutex;
24 struct kernfs_node *value_kn;
25 int irq;
26 unsigned char irq_flags;
27
28 bool direction_can_change;
29};
30
31/*
32 * Lock to serialise gpiod export and unexport, and prevent re-export of
33 * gpiod whose chip is being unregistered.
34 */
35static DEFINE_MUTEX(sysfs_lock);
36
37/*
38 * /sys/class/gpio/gpioN... only for GPIOs that are exported
39 * /direction
40 * * MAY BE OMITTED if kernel won't allow direction changes
41 * * is read/write as "in" or "out"
42 * * may also be written as "high" or "low", initializing
43 * output value as specified ("out" implies "low")
44 * /value
45 * * always readable, subject to hardware behavior
46 * * may be writable, as zero/nonzero
47 * /edge
48 * * configures behavior of poll(2) on /value
49 * * available only if pin can generate IRQs on input
50 * * is read/write as "none", "falling", "rising", or "both"
51 * /active_low
52 * * configures polarity of /value
53 * * is read/write as zero/nonzero
54 * * also affects existing and subsequent "falling" and "rising"
55 * /edge configuration
56 */
57
58static ssize_t direction_show(struct device *dev,
59 struct device_attribute *attr, char *buf)
60{
61 struct gpiod_data *data = dev_get_drvdata(dev);
62 struct gpio_desc *desc = data->desc;
63 ssize_t status;
64
65 mutex_lock(&data->mutex);
66
67 gpiod_get_direction(desc);
68 status = sprintf(buf, "%s\n",
69 test_bit(FLAG_IS_OUT, &desc->flags)
70 ? "out" : "in");
71
72 mutex_unlock(&data->mutex);
73
74 return status;
75}
76
77static ssize_t direction_store(struct device *dev,
78 struct device_attribute *attr, const char *buf, size_t size)
79{
80 struct gpiod_data *data = dev_get_drvdata(dev);
81 struct gpio_desc *desc = data->desc;
82 ssize_t status;
83
84 mutex_lock(&data->mutex);
85
86 if (sysfs_streq(buf, "high"))
87 status = gpiod_direction_output_raw(desc, 1);
88 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
89 status = gpiod_direction_output_raw(desc, 0);
90 else if (sysfs_streq(buf, "in"))
91 status = gpiod_direction_input(desc);
92 else
93 status = -EINVAL;
94
95 mutex_unlock(&data->mutex);
96
97 return status ? : size;
98}
99static DEVICE_ATTR_RW(direction);
100
101static ssize_t value_show(struct device *dev,
102 struct device_attribute *attr, char *buf)
103{
104 struct gpiod_data *data = dev_get_drvdata(dev);
105 struct gpio_desc *desc = data->desc;
106 ssize_t status;
107
108 mutex_lock(&data->mutex);
109
110 status = gpiod_get_value_cansleep(desc);
111 if (status < 0)
112 goto err;
113
114 buf[0] = '0' + status;
115 buf[1] = '\n';
116 status = 2;
117err:
118 mutex_unlock(&data->mutex);
119
120 return status;
121}
122
123static ssize_t value_store(struct device *dev,
124 struct device_attribute *attr, const char *buf, size_t size)
125{
126 struct gpiod_data *data = dev_get_drvdata(dev);
127 struct gpio_desc *desc = data->desc;
128 ssize_t status = 0;
129
130 mutex_lock(&data->mutex);
131
132 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
133 status = -EPERM;
134 } else {
135 long value;
136
137 if (size <= 2 && isdigit(buf[0]) &&
138 (size == 1 || buf[1] == '\n'))
139 value = buf[0] - '0';
140 else
141 status = kstrtol(buf, 0, &value);
142 if (status == 0) {
143 gpiod_set_value_cansleep(desc, value);
144 status = size;
145 }
146 }
147
148 mutex_unlock(&data->mutex);
149
150 return status;
151}
152static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
153
154static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
155{
156 struct gpiod_data *data = priv;
157
158 sysfs_notify_dirent(data->value_kn);
159
160 return IRQ_HANDLED;
161}
162
163/* Caller holds gpiod-data mutex. */
164static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
165{
166 struct gpiod_data *data = dev_get_drvdata(dev);
167 struct gpio_desc *desc = data->desc;
168 unsigned long irq_flags;
169 int ret;
170
171 data->irq = gpiod_to_irq(desc);
172 if (data->irq < 0)
173 return -EIO;
174
175 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
176 if (!data->value_kn)
177 return -ENODEV;
178
179 irq_flags = IRQF_SHARED;
180 if (flags & GPIO_IRQF_TRIGGER_FALLING)
181 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
182 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
183 if (flags & GPIO_IRQF_TRIGGER_RISING)
184 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
185 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
186
187 /*
188 * FIXME: This should be done in the irq_request_resources callback
189 * when the irq is requested, but a few drivers currently fail
190 * to do so.
191 *
192 * Remove this redundant call (along with the corresponding
193 * unlock) when those drivers have been fixed.
194 */
195 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
196 if (ret < 0)
197 goto err_put_kn;
198
199 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
200 "gpiolib", data);
201 if (ret < 0)
202 goto err_unlock;
203
204 data->irq_flags = flags;
205
206 return 0;
207
208err_unlock:
209 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
210err_put_kn:
211 sysfs_put(data->value_kn);
212
213 return ret;
214}
215
216/*
217 * Caller holds gpiod-data mutex (unless called after class-device
218 * deregistration).
219 */
220static void gpio_sysfs_free_irq(struct device *dev)
221{
222 struct gpiod_data *data = dev_get_drvdata(dev);
223 struct gpio_desc *desc = data->desc;
224
225 data->irq_flags = 0;
226 free_irq(data->irq, data);
227 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
228 sysfs_put(data->value_kn);
229}
230
231static const struct {
232 const char *name;
233 unsigned char flags;
234} trigger_types[] = {
235 { "none", 0 },
236 { "falling", GPIO_IRQF_TRIGGER_FALLING },
237 { "rising", GPIO_IRQF_TRIGGER_RISING },
238 { "both", GPIO_IRQF_TRIGGER_BOTH },
239};
240
241static ssize_t edge_show(struct device *dev,
242 struct device_attribute *attr, char *buf)
243{
244 struct gpiod_data *data = dev_get_drvdata(dev);
245 ssize_t status = 0;
246 int i;
247
248 mutex_lock(&data->mutex);
249
250 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
251 if (data->irq_flags == trigger_types[i].flags) {
252 status = sprintf(buf, "%s\n", trigger_types[i].name);
253 break;
254 }
255 }
256
257 mutex_unlock(&data->mutex);
258
259 return status;
260}
261
262static ssize_t edge_store(struct device *dev,
263 struct device_attribute *attr, const char *buf, size_t size)
264{
265 struct gpiod_data *data = dev_get_drvdata(dev);
266 unsigned char flags;
267 ssize_t status = size;
268 int i;
269
270 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
271 if (sysfs_streq(trigger_types[i].name, buf))
272 break;
273 }
274
275 if (i == ARRAY_SIZE(trigger_types))
276 return -EINVAL;
277
278 flags = trigger_types[i].flags;
279
280 mutex_lock(&data->mutex);
281
282 if (flags == data->irq_flags) {
283 status = size;
284 goto out_unlock;
285 }
286
287 if (data->irq_flags)
288 gpio_sysfs_free_irq(dev);
289
290 if (flags) {
291 status = gpio_sysfs_request_irq(dev, flags);
292 if (!status)
293 status = size;
294 }
295
296out_unlock:
297 mutex_unlock(&data->mutex);
298
299 return status;
300}
301static DEVICE_ATTR_RW(edge);
302
303/* Caller holds gpiod-data mutex. */
304static int gpio_sysfs_set_active_low(struct device *dev, int value)
305{
306 struct gpiod_data *data = dev_get_drvdata(dev);
307 struct gpio_desc *desc = data->desc;
308 int status = 0;
309 unsigned int flags = data->irq_flags;
310
311 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
312 return 0;
313
314 if (value)
315 set_bit(FLAG_ACTIVE_LOW, &desc->flags);
316 else
317 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
318
319 /* reconfigure poll(2) support if enabled on one edge only */
320 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
321 flags == GPIO_IRQF_TRIGGER_RISING) {
322 gpio_sysfs_free_irq(dev);
323 status = gpio_sysfs_request_irq(dev, flags);
324 }
325
326 return status;
327}
328
329static ssize_t active_low_show(struct device *dev,
330 struct device_attribute *attr, char *buf)
331{
332 struct gpiod_data *data = dev_get_drvdata(dev);
333 struct gpio_desc *desc = data->desc;
334 ssize_t status;
335
336 mutex_lock(&data->mutex);
337
338 status = sprintf(buf, "%d\n",
339 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
340
341 mutex_unlock(&data->mutex);
342
343 return status;
344}
345
346static ssize_t active_low_store(struct device *dev,
347 struct device_attribute *attr, const char *buf, size_t size)
348{
349 struct gpiod_data *data = dev_get_drvdata(dev);
350 ssize_t status;
351 long value;
352
353 mutex_lock(&data->mutex);
354
355 status = kstrtol(buf, 0, &value);
356 if (status == 0)
357 status = gpio_sysfs_set_active_low(dev, value);
358
359 mutex_unlock(&data->mutex);
360
361 return status ? : size;
362}
363static DEVICE_ATTR_RW(active_low);
364
365static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
366 int n)
367{
368 struct device *dev = container_of(kobj, struct device, kobj);
369 struct gpiod_data *data = dev_get_drvdata(dev);
370 struct gpio_desc *desc = data->desc;
371 umode_t mode = attr->mode;
372 bool show_direction = data->direction_can_change;
373
374 if (attr == &dev_attr_direction.attr) {
375 if (!show_direction)
376 mode = 0;
377 } else if (attr == &dev_attr_edge.attr) {
378 if (gpiod_to_irq(desc) < 0)
379 mode = 0;
380 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
381 mode = 0;
382 }
383
384 return mode;
385}
386
387static struct attribute *gpio_attrs[] = {
388 &dev_attr_direction.attr,
389 &dev_attr_edge.attr,
390 &dev_attr_value.attr,
391 &dev_attr_active_low.attr,
392 NULL,
393};
394
395static const struct attribute_group gpio_group = {
396 .attrs = gpio_attrs,
397 .is_visible = gpio_is_visible,
398};
399
400static const struct attribute_group *gpio_groups[] = {
401 &gpio_group,
402 NULL
403};
404
405/*
406 * /sys/class/gpio/gpiochipN/
407 * /base ... matching gpio_chip.base (N)
408 * /label ... matching gpio_chip.label
409 * /ngpio ... matching gpio_chip.ngpio
410 */
411
412static ssize_t base_show(struct device *dev,
413 struct device_attribute *attr, char *buf)
414{
415 const struct gpio_chip *chip = dev_get_drvdata(dev);
416
417 return sprintf(buf, "%d\n", chip->base);
418}
419static DEVICE_ATTR_RO(base);
420
421static ssize_t label_show(struct device *dev,
422 struct device_attribute *attr, char *buf)
423{
424 const struct gpio_chip *chip = dev_get_drvdata(dev);
425
426 return sprintf(buf, "%s\n", chip->label ? : "");
427}
428static DEVICE_ATTR_RO(label);
429
430static ssize_t ngpio_show(struct device *dev,
431 struct device_attribute *attr, char *buf)
432{
433 const struct gpio_chip *chip = dev_get_drvdata(dev);
434
435 return sprintf(buf, "%u\n", chip->ngpio);
436}
437static DEVICE_ATTR_RO(ngpio);
438
439static struct attribute *gpiochip_attrs[] = {
440 &dev_attr_base.attr,
441 &dev_attr_label.attr,
442 &dev_attr_ngpio.attr,
443 NULL,
444};
445ATTRIBUTE_GROUPS(gpiochip);
446
447/*
448 * /sys/class/gpio/export ... write-only
449 * integer N ... number of GPIO to export (full access)
450 * /sys/class/gpio/unexport ... write-only
451 * integer N ... number of GPIO to unexport
452 */
453static ssize_t export_store(struct class *class,
454 struct class_attribute *attr,
455 const char *buf, size_t len)
456{
457 long gpio;
458 struct gpio_desc *desc;
459 int status;
460
461 status = kstrtol(buf, 0, &gpio);
462 if (status < 0)
463 goto done;
464
465 desc = gpio_to_desc(gpio);
466 /* reject invalid GPIOs */
467 if (!desc) {
468 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
469 return -EINVAL;
470 }
471
472 /* No extra locking here; FLAG_SYSFS just signifies that the
473 * request and export were done by on behalf of userspace, so
474 * they may be undone on its behalf too.
475 */
476
477 status = gpiod_request(desc, "sysfs");
478 if (status < 0) {
479 if (status == -EPROBE_DEFER)
480 status = -ENODEV;
481 goto done;
482 }
483
484 status = gpiod_set_transitory(desc, false);
485 if (!status) {
486 status = gpiod_export(desc, true);
487 if (status < 0)
488 gpiod_free(desc);
489 else
490 set_bit(FLAG_SYSFS, &desc->flags);
491 }
492
493done:
494 if (status)
495 pr_debug("%s: status %d\n", __func__, status);
496 return status ? : len;
497}
498static CLASS_ATTR_WO(export);
499
500static ssize_t unexport_store(struct class *class,
501 struct class_attribute *attr,
502 const char *buf, size_t len)
503{
504 long gpio;
505 struct gpio_desc *desc;
506 int status;
507
508 status = kstrtol(buf, 0, &gpio);
509 if (status < 0)
510 goto done;
511
512 desc = gpio_to_desc(gpio);
513 /* reject bogus commands (gpio_unexport ignores them) */
514 if (!desc) {
515 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
516 return -EINVAL;
517 }
518
519 status = -EINVAL;
520
521 /* No extra locking here; FLAG_SYSFS just signifies that the
522 * request and export were done by on behalf of userspace, so
523 * they may be undone on its behalf too.
524 */
525 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
526 status = 0;
527 gpiod_free(desc);
528 }
529done:
530 if (status)
531 pr_debug("%s: status %d\n", __func__, status);
532 return status ? : len;
533}
534static CLASS_ATTR_WO(unexport);
535
536static struct attribute *gpio_class_attrs[] = {
537 &class_attr_export.attr,
538 &class_attr_unexport.attr,
539 NULL,
540};
541ATTRIBUTE_GROUPS(gpio_class);
542
543static struct class gpio_class = {
544 .name = "gpio",
545 .owner = THIS_MODULE,
546
547 .class_groups = gpio_class_groups,
548};
549
550
551/**
552 * gpiod_export - export a GPIO through sysfs
553 * @desc: GPIO to make available, already requested
554 * @direction_may_change: true if userspace may change GPIO direction
555 * Context: arch_initcall or later
556 *
557 * When drivers want to make a GPIO accessible to userspace after they
558 * have requested it -- perhaps while debugging, or as part of their
559 * public interface -- they may use this routine. If the GPIO can
560 * change direction (some can't) and the caller allows it, userspace
561 * will see "direction" sysfs attribute which may be used to change
562 * the gpio's direction. A "value" attribute will always be provided.
563 *
564 * Returns zero on success, else an error.
565 */
566int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
567{
568 struct gpio_chip *chip;
569 struct gpio_device *gdev;
570 struct gpiod_data *data;
571 unsigned long flags;
572 int status;
573 const char *ioname = NULL;
574 struct device *dev;
575 int offset;
576
577 /* can't export until sysfs is available ... */
578 if (!gpio_class.p) {
579 pr_debug("%s: called too early!\n", __func__);
580 return -ENOENT;
581 }
582
583 if (!desc) {
584 pr_debug("%s: invalid gpio descriptor\n", __func__);
585 return -EINVAL;
586 }
587
588 gdev = desc->gdev;
589 chip = gdev->chip;
590
591 mutex_lock(&sysfs_lock);
592
593 /* check if chip is being removed */
594 if (!chip || !gdev->mockdev) {
595 status = -ENODEV;
596 goto err_unlock;
597 }
598
599 spin_lock_irqsave(&gpio_lock, flags);
600 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
601 test_bit(FLAG_EXPORT, &desc->flags)) {
602 spin_unlock_irqrestore(&gpio_lock, flags);
603 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
604 __func__,
605 test_bit(FLAG_REQUESTED, &desc->flags),
606 test_bit(FLAG_EXPORT, &desc->flags));
607 status = -EPERM;
608 goto err_unlock;
609 }
610 spin_unlock_irqrestore(&gpio_lock, flags);
611
612 data = kzalloc(sizeof(*data), GFP_KERNEL);
613 if (!data) {
614 status = -ENOMEM;
615 goto err_unlock;
616 }
617
618 data->desc = desc;
619 mutex_init(&data->mutex);
620 if (chip->direction_input && chip->direction_output)
621 data->direction_can_change = direction_may_change;
622 else
623 data->direction_can_change = false;
624
625 offset = gpio_chip_hwgpio(desc);
626 if (chip->names && chip->names[offset])
627 ioname = chip->names[offset];
628
629 dev = device_create_with_groups(&gpio_class, &gdev->dev,
630 MKDEV(0, 0), data, gpio_groups,
631 ioname ? ioname : "gpio%u",
632 desc_to_gpio(desc));
633 if (IS_ERR(dev)) {
634 status = PTR_ERR(dev);
635 goto err_free_data;
636 }
637
638 set_bit(FLAG_EXPORT, &desc->flags);
639 mutex_unlock(&sysfs_lock);
640 return 0;
641
642err_free_data:
643 kfree(data);
644err_unlock:
645 mutex_unlock(&sysfs_lock);
646 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
647 return status;
648}
649EXPORT_SYMBOL_GPL(gpiod_export);
650
651static int match_export(struct device *dev, const void *desc)
652{
653 struct gpiod_data *data = dev_get_drvdata(dev);
654
655 return data->desc == desc;
656}
657
658/**
659 * gpiod_export_link - create a sysfs link to an exported GPIO node
660 * @dev: device under which to create symlink
661 * @name: name of the symlink
662 * @desc: GPIO to create symlink to, already exported
663 *
664 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
665 * node. Caller is responsible for unlinking.
666 *
667 * Returns zero on success, else an error.
668 */
669int gpiod_export_link(struct device *dev, const char *name,
670 struct gpio_desc *desc)
671{
672 struct device *cdev;
673 int ret;
674
675 if (!desc) {
676 pr_warn("%s: invalid GPIO\n", __func__);
677 return -EINVAL;
678 }
679
680 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
681 if (!cdev)
682 return -ENODEV;
683
684 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
685 put_device(cdev);
686
687 return ret;
688}
689EXPORT_SYMBOL_GPL(gpiod_export_link);
690
691/**
692 * gpiod_unexport - reverse effect of gpiod_export()
693 * @desc: GPIO to make unavailable
694 *
695 * This is implicit on gpiod_free().
696 */
697void gpiod_unexport(struct gpio_desc *desc)
698{
699 struct gpiod_data *data;
700 struct device *dev;
701
702 if (!desc) {
703 pr_warn("%s: invalid GPIO\n", __func__);
704 return;
705 }
706
707 mutex_lock(&sysfs_lock);
708
709 if (!test_bit(FLAG_EXPORT, &desc->flags))
710 goto err_unlock;
711
712 dev = class_find_device(&gpio_class, NULL, desc, match_export);
713 if (!dev)
714 goto err_unlock;
715
716 data = dev_get_drvdata(dev);
717
718 clear_bit(FLAG_EXPORT, &desc->flags);
719
720 device_unregister(dev);
721
722 /*
723 * Release irq after deregistration to prevent race with edge_store.
724 */
725 if (data->irq_flags)
726 gpio_sysfs_free_irq(dev);
727
728 mutex_unlock(&sysfs_lock);
729
730 put_device(dev);
731 kfree(data);
732
733 return;
734
735err_unlock:
736 mutex_unlock(&sysfs_lock);
737}
738EXPORT_SYMBOL_GPL(gpiod_unexport);
739
740int gpiochip_sysfs_register(struct gpio_device *gdev)
741{
742 struct device *dev;
743 struct device *parent;
744 struct gpio_chip *chip = gdev->chip;
745
746 /*
747 * Many systems add gpio chips for SOC support very early,
748 * before driver model support is available. In those cases we
749 * register later, in gpiolib_sysfs_init() ... here we just
750 * verify that _some_ field of gpio_class got initialized.
751 */
752 if (!gpio_class.p)
753 return 0;
754
755 /*
756 * For sysfs backward compatibility we need to preserve this
757 * preferred parenting to the gpio_chip parent field, if set.
758 */
759 if (chip->parent)
760 parent = chip->parent;
761 else
762 parent = &gdev->dev;
763
764 /* use chip->base for the ID; it's already known to be unique */
765 dev = device_create_with_groups(&gpio_class, parent,
766 MKDEV(0, 0),
767 chip, gpiochip_groups,
768 "gpiochip%d", chip->base);
769 if (IS_ERR(dev))
770 return PTR_ERR(dev);
771
772 mutex_lock(&sysfs_lock);
773 gdev->mockdev = dev;
774 mutex_unlock(&sysfs_lock);
775
776 return 0;
777}
778
779void gpiochip_sysfs_unregister(struct gpio_device *gdev)
780{
781 struct gpio_desc *desc;
782 struct gpio_chip *chip = gdev->chip;
783 unsigned int i;
784
785 if (!gdev->mockdev)
786 return;
787
788 device_unregister(gdev->mockdev);
789
790 /* prevent further gpiod exports */
791 mutex_lock(&sysfs_lock);
792 gdev->mockdev = NULL;
793 mutex_unlock(&sysfs_lock);
794
795 /* unregister gpiod class devices owned by sysfs */
796 for (i = 0; i < chip->ngpio; i++) {
797 desc = &gdev->descs[i];
798 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
799 gpiod_free(desc);
800 }
801}
802
803static int __init gpiolib_sysfs_init(void)
804{
805 int status;
806 unsigned long flags;
807 struct gpio_device *gdev;
808
809 status = class_register(&gpio_class);
810 if (status < 0)
811 return status;
812
813 /* Scan and register the gpio_chips which registered very
814 * early (e.g. before the class_register above was called).
815 *
816 * We run before arch_initcall() so chip->dev nodes can have
817 * registered, and so arch_initcall() can always gpio_export().
818 */
819 spin_lock_irqsave(&gpio_lock, flags);
820 list_for_each_entry(gdev, &gpio_devices, list) {
821 if (gdev->mockdev)
822 continue;
823
824 /*
825 * TODO we yield gpio_lock here because
826 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
827 * and needs to be fixed.
828 *
829 * Also it would be nice to use gpiochip_find() here so we
830 * can keep gpio_chips local to gpiolib.c, but the yield of
831 * gpio_lock prevents us from doing this.
832 */
833 spin_unlock_irqrestore(&gpio_lock, flags);
834 status = gpiochip_sysfs_register(gdev);
835 spin_lock_irqsave(&gpio_lock, flags);
836 }
837 spin_unlock_irqrestore(&gpio_lock, flags);
838
839 return status;
840}
841postcore_initcall(gpiolib_sysfs_init);