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1#include <linux/idr.h>
2#include <linux/mutex.h>
3#include <linux/device.h>
4#include <linux/sysfs.h>
5#include <linux/gpio.h>
6#include <linux/gpio/consumer.h>
7#include <linux/gpio/driver.h>
8#include <linux/interrupt.h>
9#include <linux/kdev_t.h>
10#include <linux/slab.h>
11#include <linux/ctype.h>
12
13#include "gpiolib.h"
14
15#define GPIO_IRQF_TRIGGER_FALLING BIT(0)
16#define GPIO_IRQF_TRIGGER_RISING BIT(1)
17#define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
18 GPIO_IRQF_TRIGGER_RISING)
19
20struct gpiod_data {
21 struct gpio_desc *desc;
22
23 struct mutex mutex;
24 struct kernfs_node *value_kn;
25 int irq;
26 unsigned char irq_flags;
27
28 bool direction_can_change;
29};
30
31/*
32 * Lock to serialise gpiod export and unexport, and prevent re-export of
33 * gpiod whose chip is being unregistered.
34 */
35static DEFINE_MUTEX(sysfs_lock);
36
37/*
38 * /sys/class/gpio/gpioN... only for GPIOs that are exported
39 * /direction
40 * * MAY BE OMITTED if kernel won't allow direction changes
41 * * is read/write as "in" or "out"
42 * * may also be written as "high" or "low", initializing
43 * output value as specified ("out" implies "low")
44 * /value
45 * * always readable, subject to hardware behavior
46 * * may be writable, as zero/nonzero
47 * /edge
48 * * configures behavior of poll(2) on /value
49 * * available only if pin can generate IRQs on input
50 * * is read/write as "none", "falling", "rising", or "both"
51 * /active_low
52 * * configures polarity of /value
53 * * is read/write as zero/nonzero
54 * * also affects existing and subsequent "falling" and "rising"
55 * /edge configuration
56 */
57
58static ssize_t direction_show(struct device *dev,
59 struct device_attribute *attr, char *buf)
60{
61 struct gpiod_data *data = dev_get_drvdata(dev);
62 struct gpio_desc *desc = data->desc;
63 ssize_t status;
64
65 mutex_lock(&data->mutex);
66
67 gpiod_get_direction(desc);
68 status = sprintf(buf, "%s\n",
69 test_bit(FLAG_IS_OUT, &desc->flags)
70 ? "out" : "in");
71
72 mutex_unlock(&data->mutex);
73
74 return status;
75}
76
77static ssize_t direction_store(struct device *dev,
78 struct device_attribute *attr, const char *buf, size_t size)
79{
80 struct gpiod_data *data = dev_get_drvdata(dev);
81 struct gpio_desc *desc = data->desc;
82 ssize_t status;
83
84 mutex_lock(&data->mutex);
85
86 if (sysfs_streq(buf, "high"))
87 status = gpiod_direction_output_raw(desc, 1);
88 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
89 status = gpiod_direction_output_raw(desc, 0);
90 else if (sysfs_streq(buf, "in"))
91 status = gpiod_direction_input(desc);
92 else
93 status = -EINVAL;
94
95 mutex_unlock(&data->mutex);
96
97 return status ? : size;
98}
99static DEVICE_ATTR_RW(direction);
100
101static ssize_t value_show(struct device *dev,
102 struct device_attribute *attr, char *buf)
103{
104 struct gpiod_data *data = dev_get_drvdata(dev);
105 struct gpio_desc *desc = data->desc;
106 ssize_t status;
107
108 mutex_lock(&data->mutex);
109
110 status = gpiod_get_value_cansleep(desc);
111 if (status < 0)
112 goto err;
113
114 buf[0] = '0' + status;
115 buf[1] = '\n';
116 status = 2;
117err:
118 mutex_unlock(&data->mutex);
119
120 return status;
121}
122
123static ssize_t value_store(struct device *dev,
124 struct device_attribute *attr, const char *buf, size_t size)
125{
126 struct gpiod_data *data = dev_get_drvdata(dev);
127 struct gpio_desc *desc = data->desc;
128 ssize_t status = 0;
129
130 mutex_lock(&data->mutex);
131
132 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
133 status = -EPERM;
134 } else {
135 long value;
136
137 if (size <= 2 && isdigit(buf[0]) &&
138 (size == 1 || buf[1] == '\n'))
139 value = buf[0] - '0';
140 else
141 status = kstrtol(buf, 0, &value);
142 if (status == 0) {
143 gpiod_set_value_cansleep(desc, value);
144 status = size;
145 }
146 }
147
148 mutex_unlock(&data->mutex);
149
150 return status;
151}
152static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
153
154static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
155{
156 struct gpiod_data *data = priv;
157
158 sysfs_notify_dirent(data->value_kn);
159
160 return IRQ_HANDLED;
161}
162
163/* Caller holds gpiod-data mutex. */
164static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
165{
166 struct gpiod_data *data = dev_get_drvdata(dev);
167 struct gpio_desc *desc = data->desc;
168 unsigned long irq_flags;
169 int ret;
170
171 data->irq = gpiod_to_irq(desc);
172 if (data->irq < 0)
173 return -EIO;
174
175 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
176 if (!data->value_kn)
177 return -ENODEV;
178
179 irq_flags = IRQF_SHARED;
180 if (flags & GPIO_IRQF_TRIGGER_FALLING)
181 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
182 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
183 if (flags & GPIO_IRQF_TRIGGER_RISING)
184 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
185 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
186
187 /*
188 * FIXME: This should be done in the irq_request_resources callback
189 * when the irq is requested, but a few drivers currently fail
190 * to do so.
191 *
192 * Remove this redundant call (along with the corresponding
193 * unlock) when those drivers have been fixed.
194 */
195 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
196 if (ret < 0)
197 goto err_put_kn;
198
199 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
200 "gpiolib", data);
201 if (ret < 0)
202 goto err_unlock;
203
204 data->irq_flags = flags;
205
206 return 0;
207
208err_unlock:
209 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
210err_put_kn:
211 sysfs_put(data->value_kn);
212
213 return ret;
214}
215
216/*
217 * Caller holds gpiod-data mutex (unless called after class-device
218 * deregistration).
219 */
220static void gpio_sysfs_free_irq(struct device *dev)
221{
222 struct gpiod_data *data = dev_get_drvdata(dev);
223 struct gpio_desc *desc = data->desc;
224
225 data->irq_flags = 0;
226 free_irq(data->irq, data);
227 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
228 sysfs_put(data->value_kn);
229}
230
231static const struct {
232 const char *name;
233 unsigned char flags;
234} trigger_types[] = {
235 { "none", 0 },
236 { "falling", GPIO_IRQF_TRIGGER_FALLING },
237 { "rising", GPIO_IRQF_TRIGGER_RISING },
238 { "both", GPIO_IRQF_TRIGGER_BOTH },
239};
240
241static ssize_t edge_show(struct device *dev,
242 struct device_attribute *attr, char *buf)
243{
244 struct gpiod_data *data = dev_get_drvdata(dev);
245 ssize_t status = 0;
246 int i;
247
248 mutex_lock(&data->mutex);
249
250 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
251 if (data->irq_flags == trigger_types[i].flags) {
252 status = sprintf(buf, "%s\n", trigger_types[i].name);
253 break;
254 }
255 }
256
257 mutex_unlock(&data->mutex);
258
259 return status;
260}
261
262static ssize_t edge_store(struct device *dev,
263 struct device_attribute *attr, const char *buf, size_t size)
264{
265 struct gpiod_data *data = dev_get_drvdata(dev);
266 unsigned char flags;
267 ssize_t status = size;
268 int i;
269
270 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
271 if (sysfs_streq(trigger_types[i].name, buf))
272 break;
273 }
274
275 if (i == ARRAY_SIZE(trigger_types))
276 return -EINVAL;
277
278 flags = trigger_types[i].flags;
279
280 mutex_lock(&data->mutex);
281
282 if (flags == data->irq_flags) {
283 status = size;
284 goto out_unlock;
285 }
286
287 if (data->irq_flags)
288 gpio_sysfs_free_irq(dev);
289
290 if (flags) {
291 status = gpio_sysfs_request_irq(dev, flags);
292 if (!status)
293 status = size;
294 }
295
296out_unlock:
297 mutex_unlock(&data->mutex);
298
299 return status;
300}
301static DEVICE_ATTR_RW(edge);
302
303/* Caller holds gpiod-data mutex. */
304static int gpio_sysfs_set_active_low(struct device *dev, int value)
305{
306 struct gpiod_data *data = dev_get_drvdata(dev);
307 struct gpio_desc *desc = data->desc;
308 int status = 0;
309 unsigned int flags = data->irq_flags;
310
311 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
312 return 0;
313
314 if (value)
315 set_bit(FLAG_ACTIVE_LOW, &desc->flags);
316 else
317 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
318
319 /* reconfigure poll(2) support if enabled on one edge only */
320 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
321 flags == GPIO_IRQF_TRIGGER_RISING) {
322 gpio_sysfs_free_irq(dev);
323 status = gpio_sysfs_request_irq(dev, flags);
324 }
325
326 return status;
327}
328
329static ssize_t active_low_show(struct device *dev,
330 struct device_attribute *attr, char *buf)
331{
332 struct gpiod_data *data = dev_get_drvdata(dev);
333 struct gpio_desc *desc = data->desc;
334 ssize_t status;
335
336 mutex_lock(&data->mutex);
337
338 status = sprintf(buf, "%d\n",
339 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
340
341 mutex_unlock(&data->mutex);
342
343 return status;
344}
345
346static ssize_t active_low_store(struct device *dev,
347 struct device_attribute *attr, const char *buf, size_t size)
348{
349 struct gpiod_data *data = dev_get_drvdata(dev);
350 ssize_t status;
351 long value;
352
353 mutex_lock(&data->mutex);
354
355 status = kstrtol(buf, 0, &value);
356 if (status == 0)
357 status = gpio_sysfs_set_active_low(dev, value);
358
359 mutex_unlock(&data->mutex);
360
361 return status ? : size;
362}
363static DEVICE_ATTR_RW(active_low);
364
365static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
366 int n)
367{
368 struct device *dev = container_of(kobj, struct device, kobj);
369 struct gpiod_data *data = dev_get_drvdata(dev);
370 struct gpio_desc *desc = data->desc;
371 umode_t mode = attr->mode;
372 bool show_direction = data->direction_can_change;
373
374 if (attr == &dev_attr_direction.attr) {
375 if (!show_direction)
376 mode = 0;
377 } else if (attr == &dev_attr_edge.attr) {
378 if (gpiod_to_irq(desc) < 0)
379 mode = 0;
380 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
381 mode = 0;
382 }
383
384 return mode;
385}
386
387static struct attribute *gpio_attrs[] = {
388 &dev_attr_direction.attr,
389 &dev_attr_edge.attr,
390 &dev_attr_value.attr,
391 &dev_attr_active_low.attr,
392 NULL,
393};
394
395static const struct attribute_group gpio_group = {
396 .attrs = gpio_attrs,
397 .is_visible = gpio_is_visible,
398};
399
400static const struct attribute_group *gpio_groups[] = {
401 &gpio_group,
402 NULL
403};
404
405/*
406 * /sys/class/gpio/gpiochipN/
407 * /base ... matching gpio_chip.base (N)
408 * /label ... matching gpio_chip.label
409 * /ngpio ... matching gpio_chip.ngpio
410 */
411
412static ssize_t base_show(struct device *dev,
413 struct device_attribute *attr, char *buf)
414{
415 const struct gpio_chip *chip = dev_get_drvdata(dev);
416
417 return sprintf(buf, "%d\n", chip->base);
418}
419static DEVICE_ATTR_RO(base);
420
421static ssize_t label_show(struct device *dev,
422 struct device_attribute *attr, char *buf)
423{
424 const struct gpio_chip *chip = dev_get_drvdata(dev);
425
426 return sprintf(buf, "%s\n", chip->label ? : "");
427}
428static DEVICE_ATTR_RO(label);
429
430static ssize_t ngpio_show(struct device *dev,
431 struct device_attribute *attr, char *buf)
432{
433 const struct gpio_chip *chip = dev_get_drvdata(dev);
434
435 return sprintf(buf, "%u\n", chip->ngpio);
436}
437static DEVICE_ATTR_RO(ngpio);
438
439static struct attribute *gpiochip_attrs[] = {
440 &dev_attr_base.attr,
441 &dev_attr_label.attr,
442 &dev_attr_ngpio.attr,
443 NULL,
444};
445ATTRIBUTE_GROUPS(gpiochip);
446
447static struct gpio_desc *gpio_to_valid_desc(int gpio)
448{
449 return gpio_is_valid(gpio) ? gpio_to_desc(gpio) : NULL;
450}
451
452/*
453 * /sys/class/gpio/export ... write-only
454 * integer N ... number of GPIO to export (full access)
455 * /sys/class/gpio/unexport ... write-only
456 * integer N ... number of GPIO to unexport
457 */
458static ssize_t export_store(struct class *class,
459 struct class_attribute *attr,
460 const char *buf, size_t len)
461{
462 long gpio;
463 struct gpio_desc *desc;
464 int status;
465
466 status = kstrtol(buf, 0, &gpio);
467 if (status < 0)
468 goto done;
469
470 desc = gpio_to_valid_desc(gpio);
471 /* reject invalid GPIOs */
472 if (!desc) {
473 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
474 return -EINVAL;
475 }
476
477 /* No extra locking here; FLAG_SYSFS just signifies that the
478 * request and export were done by on behalf of userspace, so
479 * they may be undone on its behalf too.
480 */
481
482 status = gpiod_request(desc, "sysfs");
483 if (status < 0) {
484 if (status == -EPROBE_DEFER)
485 status = -ENODEV;
486 goto done;
487 }
488
489 status = gpiod_set_transitory(desc, false);
490 if (!status) {
491 status = gpiod_export(desc, true);
492 if (status < 0)
493 gpiod_free(desc);
494 else
495 set_bit(FLAG_SYSFS, &desc->flags);
496 }
497
498done:
499 if (status)
500 pr_debug("%s: status %d\n", __func__, status);
501 return status ? : len;
502}
503static CLASS_ATTR_WO(export);
504
505static ssize_t unexport_store(struct class *class,
506 struct class_attribute *attr,
507 const char *buf, size_t len)
508{
509 long gpio;
510 struct gpio_desc *desc;
511 int status;
512
513 status = kstrtol(buf, 0, &gpio);
514 if (status < 0)
515 goto done;
516
517 desc = gpio_to_valid_desc(gpio);
518 /* reject bogus commands (gpio_unexport ignores them) */
519 if (!desc) {
520 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
521 return -EINVAL;
522 }
523
524 status = -EINVAL;
525
526 /* No extra locking here; FLAG_SYSFS just signifies that the
527 * request and export were done by on behalf of userspace, so
528 * they may be undone on its behalf too.
529 */
530 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
531 status = 0;
532 gpiod_free(desc);
533 }
534done:
535 if (status)
536 pr_debug("%s: status %d\n", __func__, status);
537 return status ? : len;
538}
539static CLASS_ATTR_WO(unexport);
540
541static struct attribute *gpio_class_attrs[] = {
542 &class_attr_export.attr,
543 &class_attr_unexport.attr,
544 NULL,
545};
546ATTRIBUTE_GROUPS(gpio_class);
547
548static struct class gpio_class = {
549 .name = "gpio",
550 .owner = THIS_MODULE,
551
552 .class_groups = gpio_class_groups,
553};
554
555
556/**
557 * gpiod_export - export a GPIO through sysfs
558 * @desc: GPIO to make available, already requested
559 * @direction_may_change: true if userspace may change GPIO direction
560 * Context: arch_initcall or later
561 *
562 * When drivers want to make a GPIO accessible to userspace after they
563 * have requested it -- perhaps while debugging, or as part of their
564 * public interface -- they may use this routine. If the GPIO can
565 * change direction (some can't) and the caller allows it, userspace
566 * will see "direction" sysfs attribute which may be used to change
567 * the gpio's direction. A "value" attribute will always be provided.
568 *
569 * Returns zero on success, else an error.
570 */
571int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
572{
573 struct gpio_chip *chip;
574 struct gpio_device *gdev;
575 struct gpiod_data *data;
576 unsigned long flags;
577 int status;
578 const char *ioname = NULL;
579 struct device *dev;
580 int offset;
581
582 /* can't export until sysfs is available ... */
583 if (!gpio_class.p) {
584 pr_debug("%s: called too early!\n", __func__);
585 return -ENOENT;
586 }
587
588 if (!desc) {
589 pr_debug("%s: invalid gpio descriptor\n", __func__);
590 return -EINVAL;
591 }
592
593 gdev = desc->gdev;
594 chip = gdev->chip;
595
596 mutex_lock(&sysfs_lock);
597
598 /* check if chip is being removed */
599 if (!chip || !gdev->mockdev) {
600 status = -ENODEV;
601 goto err_unlock;
602 }
603
604 spin_lock_irqsave(&gpio_lock, flags);
605 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
606 test_bit(FLAG_EXPORT, &desc->flags)) {
607 spin_unlock_irqrestore(&gpio_lock, flags);
608 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
609 __func__,
610 test_bit(FLAG_REQUESTED, &desc->flags),
611 test_bit(FLAG_EXPORT, &desc->flags));
612 status = -EPERM;
613 goto err_unlock;
614 }
615 spin_unlock_irqrestore(&gpio_lock, flags);
616
617 data = kzalloc(sizeof(*data), GFP_KERNEL);
618 if (!data) {
619 status = -ENOMEM;
620 goto err_unlock;
621 }
622
623 data->desc = desc;
624 mutex_init(&data->mutex);
625 if (chip->direction_input && chip->direction_output)
626 data->direction_can_change = direction_may_change;
627 else
628 data->direction_can_change = false;
629
630 offset = gpio_chip_hwgpio(desc);
631 if (chip->names && chip->names[offset])
632 ioname = chip->names[offset];
633
634 dev = device_create_with_groups(&gpio_class, &gdev->dev,
635 MKDEV(0, 0), data, gpio_groups,
636 ioname ? ioname : "gpio%u",
637 desc_to_gpio(desc));
638 if (IS_ERR(dev)) {
639 status = PTR_ERR(dev);
640 goto err_free_data;
641 }
642
643 set_bit(FLAG_EXPORT, &desc->flags);
644 mutex_unlock(&sysfs_lock);
645 return 0;
646
647err_free_data:
648 kfree(data);
649err_unlock:
650 mutex_unlock(&sysfs_lock);
651 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
652 return status;
653}
654EXPORT_SYMBOL_GPL(gpiod_export);
655
656static int match_export(struct device *dev, const void *desc)
657{
658 struct gpiod_data *data = dev_get_drvdata(dev);
659
660 return data->desc == desc;
661}
662
663/**
664 * gpiod_export_link - create a sysfs link to an exported GPIO node
665 * @dev: device under which to create symlink
666 * @name: name of the symlink
667 * @desc: GPIO to create symlink to, already exported
668 *
669 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
670 * node. Caller is responsible for unlinking.
671 *
672 * Returns zero on success, else an error.
673 */
674int gpiod_export_link(struct device *dev, const char *name,
675 struct gpio_desc *desc)
676{
677 struct device *cdev;
678 int ret;
679
680 if (!desc) {
681 pr_warn("%s: invalid GPIO\n", __func__);
682 return -EINVAL;
683 }
684
685 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
686 if (!cdev)
687 return -ENODEV;
688
689 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
690 put_device(cdev);
691
692 return ret;
693}
694EXPORT_SYMBOL_GPL(gpiod_export_link);
695
696/**
697 * gpiod_unexport - reverse effect of gpiod_export()
698 * @desc: GPIO to make unavailable
699 *
700 * This is implicit on gpiod_free().
701 */
702void gpiod_unexport(struct gpio_desc *desc)
703{
704 struct gpiod_data *data;
705 struct device *dev;
706
707 if (!desc) {
708 pr_warn("%s: invalid GPIO\n", __func__);
709 return;
710 }
711
712 mutex_lock(&sysfs_lock);
713
714 if (!test_bit(FLAG_EXPORT, &desc->flags))
715 goto err_unlock;
716
717 dev = class_find_device(&gpio_class, NULL, desc, match_export);
718 if (!dev)
719 goto err_unlock;
720
721 data = dev_get_drvdata(dev);
722
723 clear_bit(FLAG_EXPORT, &desc->flags);
724
725 device_unregister(dev);
726
727 /*
728 * Release irq after deregistration to prevent race with edge_store.
729 */
730 if (data->irq_flags)
731 gpio_sysfs_free_irq(dev);
732
733 mutex_unlock(&sysfs_lock);
734
735 put_device(dev);
736 kfree(data);
737
738 return;
739
740err_unlock:
741 mutex_unlock(&sysfs_lock);
742}
743EXPORT_SYMBOL_GPL(gpiod_unexport);
744
745int gpiochip_sysfs_register(struct gpio_device *gdev)
746{
747 struct device *dev;
748 struct device *parent;
749 struct gpio_chip *chip = gdev->chip;
750
751 /*
752 * Many systems add gpio chips for SOC support very early,
753 * before driver model support is available. In those cases we
754 * register later, in gpiolib_sysfs_init() ... here we just
755 * verify that _some_ field of gpio_class got initialized.
756 */
757 if (!gpio_class.p)
758 return 0;
759
760 /*
761 * For sysfs backward compatibility we need to preserve this
762 * preferred parenting to the gpio_chip parent field, if set.
763 */
764 if (chip->parent)
765 parent = chip->parent;
766 else
767 parent = &gdev->dev;
768
769 /* use chip->base for the ID; it's already known to be unique */
770 dev = device_create_with_groups(&gpio_class, parent,
771 MKDEV(0, 0),
772 chip, gpiochip_groups,
773 "gpiochip%d", chip->base);
774 if (IS_ERR(dev))
775 return PTR_ERR(dev);
776
777 mutex_lock(&sysfs_lock);
778 gdev->mockdev = dev;
779 mutex_unlock(&sysfs_lock);
780
781 return 0;
782}
783
784void gpiochip_sysfs_unregister(struct gpio_device *gdev)
785{
786 struct gpio_desc *desc;
787 struct gpio_chip *chip = gdev->chip;
788 unsigned int i;
789
790 if (!gdev->mockdev)
791 return;
792
793 device_unregister(gdev->mockdev);
794
795 /* prevent further gpiod exports */
796 mutex_lock(&sysfs_lock);
797 gdev->mockdev = NULL;
798 mutex_unlock(&sysfs_lock);
799
800 /* unregister gpiod class devices owned by sysfs */
801 for (i = 0; i < chip->ngpio; i++) {
802 desc = &gdev->descs[i];
803 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
804 gpiod_free(desc);
805 }
806}
807
808static int __init gpiolib_sysfs_init(void)
809{
810 int status;
811 unsigned long flags;
812 struct gpio_device *gdev;
813
814 status = class_register(&gpio_class);
815 if (status < 0)
816 return status;
817
818 /* Scan and register the gpio_chips which registered very
819 * early (e.g. before the class_register above was called).
820 *
821 * We run before arch_initcall() so chip->dev nodes can have
822 * registered, and so arch_initcall() can always gpio_export().
823 */
824 spin_lock_irqsave(&gpio_lock, flags);
825 list_for_each_entry(gdev, &gpio_devices, list) {
826 if (gdev->mockdev)
827 continue;
828
829 /*
830 * TODO we yield gpio_lock here because
831 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
832 * and needs to be fixed.
833 *
834 * Also it would be nice to use gpiochip_find() here so we
835 * can keep gpio_chips local to gpiolib.c, but the yield of
836 * gpio_lock prevents us from doing this.
837 */
838 spin_unlock_irqrestore(&gpio_lock, flags);
839 status = gpiochip_sysfs_register(gdev);
840 spin_lock_irqsave(&gpio_lock, flags);
841 }
842 spin_unlock_irqrestore(&gpio_lock, flags);
843
844 return status;
845}
846postcore_initcall(gpiolib_sysfs_init);
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);