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