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 "gpiolib.h"
25 #include "gpiolib-sysfs.h"
26
27 struct kernfs_node;
28
29 #define GPIO_IRQF_TRIGGER_NONE 0
30 #define GPIO_IRQF_TRIGGER_FALLING BIT(0)
31 #define GPIO_IRQF_TRIGGER_RISING BIT(1)
32 #define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
33 GPIO_IRQF_TRIGGER_RISING)
34
35 struct gpiod_data {
36 struct gpio_desc *desc;
37
38 struct mutex mutex;
39 struct kernfs_node *value_kn;
40 int irq;
41 unsigned char irq_flags;
42
43 bool direction_can_change;
44 };
45
46 /*
47 * Lock to serialise gpiod export and unexport, and prevent re-export of
48 * gpiod whose chip is being unregistered.
49 */
50 static DEFINE_MUTEX(sysfs_lock);
51
52 /*
53 * /sys/class/gpio/gpioN... only for GPIOs that are exported
54 * /direction
55 * * MAY BE OMITTED if kernel won't allow direction changes
56 * * is read/write as "in" or "out"
57 * * may also be written as "high" or "low", initializing
58 * output value as specified ("out" implies "low")
59 * /value
60 * * always readable, subject to hardware behavior
61 * * may be writable, as zero/nonzero
62 * /edge
63 * * configures behavior of poll(2) on /value
64 * * available only if pin can generate IRQs on input
65 * * is read/write as "none", "falling", "rising", or "both"
66 * /active_low
67 * * configures polarity of /value
68 * * is read/write as zero/nonzero
69 * * also affects existing and subsequent "falling" and "rising"
70 * /edge configuration
71 */
72
direction_show(struct device * dev,struct device_attribute * attr,char * buf)73 static ssize_t direction_show(struct device *dev,
74 struct device_attribute *attr, char *buf)
75 {
76 struct gpiod_data *data = dev_get_drvdata(dev);
77 struct gpio_desc *desc = data->desc;
78 int value;
79
80 mutex_lock(&data->mutex);
81
82 gpiod_get_direction(desc);
83 value = !!test_bit(FLAG_IS_OUT, &desc->flags);
84
85 mutex_unlock(&data->mutex);
86
87 return sysfs_emit(buf, "%s\n", value ? "out" : "in");
88 }
89
direction_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)90 static 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 mutex_lock(&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 mutex_unlock(&data->mutex);
109
110 return status ? : size;
111 }
112 static DEVICE_ATTR_RW(direction);
113
value_show(struct device * dev,struct device_attribute * attr,char * buf)114 static ssize_t value_show(struct device *dev,
115 struct device_attribute *attr, char *buf)
116 {
117 struct gpiod_data *data = dev_get_drvdata(dev);
118 struct gpio_desc *desc = data->desc;
119 ssize_t status;
120
121 mutex_lock(&data->mutex);
122
123 status = gpiod_get_value_cansleep(desc);
124
125 mutex_unlock(&data->mutex);
126
127 if (status < 0)
128 return status;
129
130 return sysfs_emit(buf, "%zd\n", status);
131 }
132
value_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)133 static ssize_t value_store(struct device *dev,
134 struct device_attribute *attr, const char *buf, size_t size)
135 {
136 struct gpiod_data *data = dev_get_drvdata(dev);
137 struct gpio_desc *desc = data->desc;
138 ssize_t status;
139 long value;
140
141 status = kstrtol(buf, 0, &value);
142
143 mutex_lock(&data->mutex);
144
145 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
146 status = -EPERM;
147 } else if (status == 0) {
148 gpiod_set_value_cansleep(desc, value);
149 status = size;
150 }
151
152 mutex_unlock(&data->mutex);
153
154 return status;
155 }
156 static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
157
gpio_sysfs_irq(int irq,void * priv)158 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
159 {
160 struct gpiod_data *data = priv;
161
162 sysfs_notify_dirent(data->value_kn);
163
164 return IRQ_HANDLED;
165 }
166
167 /* Caller holds gpiod-data mutex. */
gpio_sysfs_request_irq(struct device * dev,unsigned char flags)168 static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
169 {
170 struct gpiod_data *data = dev_get_drvdata(dev);
171 struct gpio_desc *desc = data->desc;
172 unsigned long irq_flags;
173 int ret;
174
175 CLASS(gpio_chip_guard, guard)(desc);
176 if (!guard.gc)
177 return -ENODEV;
178
179 data->irq = gpiod_to_irq(desc);
180 if (data->irq < 0)
181 return -EIO;
182
183 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
184 if (!data->value_kn)
185 return -ENODEV;
186
187 irq_flags = IRQF_SHARED;
188 if (flags & GPIO_IRQF_TRIGGER_FALLING)
189 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
190 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
191 if (flags & GPIO_IRQF_TRIGGER_RISING)
192 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
193 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
194
195 /*
196 * FIXME: This should be done in the irq_request_resources callback
197 * when the irq is requested, but a few drivers currently fail
198 * to do so.
199 *
200 * Remove this redundant call (along with the corresponding
201 * unlock) when those drivers have been fixed.
202 */
203 ret = gpiochip_lock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
204 if (ret < 0)
205 goto err_put_kn;
206
207 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
208 "gpiolib", data);
209 if (ret < 0)
210 goto err_unlock;
211
212 data->irq_flags = flags;
213
214 return 0;
215
216 err_unlock:
217 gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
218 err_put_kn:
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 */
gpio_sysfs_free_irq(struct device * dev)228 static 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 sysfs_put(data->value_kn);
241 }
242
243 static const char * const trigger_names[] = {
244 [GPIO_IRQF_TRIGGER_NONE] = "none",
245 [GPIO_IRQF_TRIGGER_FALLING] = "falling",
246 [GPIO_IRQF_TRIGGER_RISING] = "rising",
247 [GPIO_IRQF_TRIGGER_BOTH] = "both",
248 };
249
edge_show(struct device * dev,struct device_attribute * attr,char * buf)250 static ssize_t edge_show(struct device *dev,
251 struct device_attribute *attr, char *buf)
252 {
253 struct gpiod_data *data = dev_get_drvdata(dev);
254 int flags;
255
256 mutex_lock(&data->mutex);
257
258 flags = data->irq_flags;
259
260 mutex_unlock(&data->mutex);
261
262 if (flags >= ARRAY_SIZE(trigger_names))
263 return 0;
264
265 return sysfs_emit(buf, "%s\n", trigger_names[flags]);
266 }
267
edge_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)268 static ssize_t edge_store(struct device *dev,
269 struct device_attribute *attr, const char *buf, size_t size)
270 {
271 struct gpiod_data *data = dev_get_drvdata(dev);
272 ssize_t status = size;
273 int flags;
274
275 flags = sysfs_match_string(trigger_names, buf);
276 if (flags < 0)
277 return flags;
278
279 mutex_lock(&data->mutex);
280
281 if (flags == data->irq_flags) {
282 status = size;
283 goto out_unlock;
284 }
285
286 if (data->irq_flags)
287 gpio_sysfs_free_irq(dev);
288
289 if (flags) {
290 status = gpio_sysfs_request_irq(dev, flags);
291 if (!status)
292 status = size;
293 }
294
295 out_unlock:
296 mutex_unlock(&data->mutex);
297
298 return status;
299 }
300 static DEVICE_ATTR_RW(edge);
301
302 /* Caller holds gpiod-data mutex. */
gpio_sysfs_set_active_low(struct device * dev,int value)303 static int gpio_sysfs_set_active_low(struct device *dev, int value)
304 {
305 struct gpiod_data *data = dev_get_drvdata(dev);
306 unsigned int flags = data->irq_flags;
307 struct gpio_desc *desc = data->desc;
308 int status = 0;
309
310
311 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
312 return 0;
313
314 assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
315
316 /* reconfigure poll(2) support if enabled on one edge only */
317 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
318 flags == GPIO_IRQF_TRIGGER_RISING) {
319 gpio_sysfs_free_irq(dev);
320 status = gpio_sysfs_request_irq(dev, flags);
321 }
322
323 return status;
324 }
325
active_low_show(struct device * dev,struct device_attribute * attr,char * buf)326 static ssize_t active_low_show(struct device *dev,
327 struct device_attribute *attr, char *buf)
328 {
329 struct gpiod_data *data = dev_get_drvdata(dev);
330 struct gpio_desc *desc = data->desc;
331 int value;
332
333 mutex_lock(&data->mutex);
334
335 value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
336
337 mutex_unlock(&data->mutex);
338
339 return sysfs_emit(buf, "%d\n", value);
340 }
341
active_low_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)342 static ssize_t active_low_store(struct device *dev,
343 struct device_attribute *attr, const char *buf, size_t size)
344 {
345 struct gpiod_data *data = dev_get_drvdata(dev);
346 ssize_t status;
347 long value;
348
349 status = kstrtol(buf, 0, &value);
350 if (status)
351 return status;
352
353 mutex_lock(&data->mutex);
354
355 status = gpio_sysfs_set_active_low(dev, value);
356
357 mutex_unlock(&data->mutex);
358
359 return status ? : size;
360 }
361 static DEVICE_ATTR_RW(active_low);
362
gpio_is_visible(struct kobject * kobj,struct attribute * attr,int n)363 static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
364 int n)
365 {
366 struct device *dev = kobj_to_dev(kobj);
367 struct gpiod_data *data = dev_get_drvdata(dev);
368 struct gpio_desc *desc = data->desc;
369 umode_t mode = attr->mode;
370 bool show_direction = data->direction_can_change;
371
372 if (attr == &dev_attr_direction.attr) {
373 if (!show_direction)
374 mode = 0;
375 } else if (attr == &dev_attr_edge.attr) {
376 if (gpiod_to_irq(desc) < 0)
377 mode = 0;
378 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
379 mode = 0;
380 }
381
382 return mode;
383 }
384
385 static struct attribute *gpio_attrs[] = {
386 &dev_attr_direction.attr,
387 &dev_attr_edge.attr,
388 &dev_attr_value.attr,
389 &dev_attr_active_low.attr,
390 NULL,
391 };
392
393 static const struct attribute_group gpio_group = {
394 .attrs = gpio_attrs,
395 .is_visible = gpio_is_visible,
396 };
397
398 static const struct attribute_group *gpio_groups[] = {
399 &gpio_group,
400 NULL
401 };
402
403 /*
404 * /sys/class/gpio/gpiochipN/
405 * /base ... matching gpio_chip.base (N)
406 * /label ... matching gpio_chip.label
407 * /ngpio ... matching gpio_chip.ngpio
408 */
409
base_show(struct device * dev,struct device_attribute * attr,char * buf)410 static ssize_t base_show(struct device *dev,
411 struct device_attribute *attr, char *buf)
412 {
413 const struct gpio_device *gdev = dev_get_drvdata(dev);
414
415 return sysfs_emit(buf, "%u\n", gdev->base);
416 }
417 static DEVICE_ATTR_RO(base);
418
label_show(struct device * dev,struct device_attribute * attr,char * buf)419 static ssize_t label_show(struct device *dev,
420 struct device_attribute *attr, char *buf)
421 {
422 const struct gpio_device *gdev = dev_get_drvdata(dev);
423
424 return sysfs_emit(buf, "%s\n", gdev->label);
425 }
426 static DEVICE_ATTR_RO(label);
427
ngpio_show(struct device * dev,struct device_attribute * attr,char * buf)428 static ssize_t ngpio_show(struct device *dev,
429 struct device_attribute *attr, char *buf)
430 {
431 const struct gpio_device *gdev = dev_get_drvdata(dev);
432
433 return sysfs_emit(buf, "%u\n", gdev->ngpio);
434 }
435 static DEVICE_ATTR_RO(ngpio);
436
437 static struct attribute *gpiochip_attrs[] = {
438 &dev_attr_base.attr,
439 &dev_attr_label.attr,
440 &dev_attr_ngpio.attr,
441 NULL,
442 };
443 ATTRIBUTE_GROUPS(gpiochip);
444
445 /*
446 * /sys/class/gpio/export ... write-only
447 * integer N ... number of GPIO to export (full access)
448 * /sys/class/gpio/unexport ... write-only
449 * integer N ... number of GPIO to unexport
450 */
export_store(const struct class * class,const struct class_attribute * attr,const char * buf,size_t len)451 static ssize_t export_store(const struct class *class,
452 const struct class_attribute *attr,
453 const char *buf, size_t len)
454 {
455 struct gpio_desc *desc;
456 int status, offset;
457 long gpio;
458
459 status = kstrtol(buf, 0, &gpio);
460 if (status)
461 return status;
462
463 desc = gpio_to_desc(gpio);
464 /* reject invalid GPIOs */
465 if (!desc) {
466 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
467 return -EINVAL;
468 }
469
470 CLASS(gpio_chip_guard, guard)(desc);
471 if (!guard.gc)
472 return -ENODEV;
473
474 offset = gpio_chip_hwgpio(desc);
475 if (!gpiochip_line_is_valid(guard.gc, offset)) {
476 pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
477 return -EINVAL;
478 }
479
480 /* No extra locking here; FLAG_SYSFS just signifies that the
481 * request and export were done by on behalf of userspace, so
482 * they may be undone on its behalf too.
483 */
484
485 status = gpiod_request_user(desc, "sysfs");
486 if (status)
487 goto done;
488
489 status = gpiod_set_transitory(desc, false);
490 if (status) {
491 gpiod_free(desc);
492 goto done;
493 }
494
495 status = gpiod_export(desc, true);
496 if (status < 0)
497 gpiod_free(desc);
498 else
499 set_bit(FLAG_SYSFS, &desc->flags);
500
501 done:
502 if (status)
503 pr_debug("%s: status %d\n", __func__, status);
504 return status ? : len;
505 }
506 static CLASS_ATTR_WO(export);
507
unexport_store(const struct class * class,const struct class_attribute * attr,const char * buf,size_t len)508 static ssize_t unexport_store(const struct class *class,
509 const struct class_attribute *attr,
510 const char *buf, size_t len)
511 {
512 struct gpio_desc *desc;
513 int status;
514 long gpio;
515
516 status = kstrtol(buf, 0, &gpio);
517 if (status < 0)
518 goto done;
519
520 desc = gpio_to_desc(gpio);
521 /* reject bogus commands (gpiod_unexport() ignores them) */
522 if (!desc) {
523 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
524 return -EINVAL;
525 }
526
527 status = -EINVAL;
528
529 /* No extra locking here; FLAG_SYSFS just signifies that the
530 * request and export were done by on behalf of userspace, so
531 * they may be undone on its behalf too.
532 */
533 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
534 gpiod_unexport(desc);
535 gpiod_free(desc);
536 status = 0;
537 }
538 done:
539 if (status)
540 pr_debug("%s: status %d\n", __func__, status);
541 return status ? : len;
542 }
543 static CLASS_ATTR_WO(unexport);
544
545 static struct attribute *gpio_class_attrs[] = {
546 &class_attr_export.attr,
547 &class_attr_unexport.attr,
548 NULL,
549 };
550 ATTRIBUTE_GROUPS(gpio_class);
551
552 static struct class gpio_class = {
553 .name = "gpio",
554 .class_groups = gpio_class_groups,
555 };
556
557
558 /**
559 * gpiod_export - export a GPIO through sysfs
560 * @desc: GPIO to make available, already requested
561 * @direction_may_change: true if userspace may change GPIO direction
562 * Context: arch_initcall or later
563 *
564 * When drivers want to make a GPIO accessible to userspace after they
565 * have requested it -- perhaps while debugging, or as part of their
566 * public interface -- they may use this routine. If the GPIO can
567 * change direction (some can't) and the caller allows it, userspace
568 * will see "direction" sysfs attribute which may be used to change
569 * the gpio's direction. A "value" attribute will always be provided.
570 *
571 * Returns:
572 * 0 on success, or negative errno on failure.
573 */
gpiod_export(struct gpio_desc * desc,bool direction_may_change)574 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
575 {
576 const char *ioname = NULL;
577 struct gpio_device *gdev;
578 struct gpiod_data *data;
579 struct device *dev;
580 int status, offset;
581
582 /* can't export until sysfs is available ... */
583 if (!class_is_registered(&gpio_class)) {
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 CLASS(gpio_chip_guard, guard)(desc);
594 if (!guard.gc)
595 return -ENODEV;
596
597 if (test_and_set_bit(FLAG_EXPORT, &desc->flags))
598 return -EPERM;
599
600 gdev = desc->gdev;
601
602 mutex_lock(&sysfs_lock);
603
604 /* check if chip is being removed */
605 if (!gdev->mockdev) {
606 status = -ENODEV;
607 goto err_unlock;
608 }
609
610 if (!test_bit(FLAG_REQUESTED, &desc->flags)) {
611 gpiod_dbg(desc, "%s: unavailable (not requested)\n", __func__);
612 status = -EPERM;
613 goto err_unlock;
614 }
615
616 data = kzalloc(sizeof(*data), GFP_KERNEL);
617 if (!data) {
618 status = -ENOMEM;
619 goto err_unlock;
620 }
621
622 data->desc = desc;
623 mutex_init(&data->mutex);
624 if (guard.gc->direction_input && guard.gc->direction_output)
625 data->direction_can_change = direction_may_change;
626 else
627 data->direction_can_change = false;
628
629 offset = gpio_chip_hwgpio(desc);
630 if (guard.gc->names && guard.gc->names[offset])
631 ioname = guard.gc->names[offset];
632
633 dev = device_create_with_groups(&gpio_class, &gdev->dev,
634 MKDEV(0, 0), data, gpio_groups,
635 ioname ? ioname : "gpio%u",
636 desc_to_gpio(desc));
637 if (IS_ERR(dev)) {
638 status = PTR_ERR(dev);
639 goto err_free_data;
640 }
641
642 mutex_unlock(&sysfs_lock);
643 return 0;
644
645 err_free_data:
646 kfree(data);
647 err_unlock:
648 mutex_unlock(&sysfs_lock);
649 clear_bit(FLAG_EXPORT, &desc->flags);
650 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
651 return status;
652 }
653 EXPORT_SYMBOL_GPL(gpiod_export);
654
match_export(struct device * dev,const void * desc)655 static int match_export(struct device *dev, const void *desc)
656 {
657 struct gpiod_data *data = dev_get_drvdata(dev);
658
659 return data->desc == desc;
660 }
661
662 /**
663 * gpiod_export_link - create a sysfs link to an exported GPIO node
664 * @dev: device under which to create symlink
665 * @name: name of the symlink
666 * @desc: GPIO to create symlink to, already exported
667 *
668 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
669 * node. Caller is responsible for unlinking.
670 *
671 * Returns:
672 * 0 on success, or negative errno on failure.
673 */
gpiod_export_link(struct device * dev,const char * name,struct gpio_desc * desc)674 int 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 }
694 EXPORT_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 */
gpiod_unexport(struct gpio_desc * desc)702 void 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
740 err_unlock:
741 mutex_unlock(&sysfs_lock);
742 }
743 EXPORT_SYMBOL_GPL(gpiod_unexport);
744
gpiochip_sysfs_register(struct gpio_device * gdev)745 int gpiochip_sysfs_register(struct gpio_device *gdev)
746 {
747 struct gpio_chip *chip;
748 struct device *parent;
749 struct device *dev;
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 (!class_is_registered(&gpio_class))
758 return 0;
759
760 guard(srcu)(&gdev->srcu);
761
762 chip = srcu_dereference(gdev->chip, &gdev->srcu);
763 if (!chip)
764 return -ENODEV;
765
766 /*
767 * For sysfs backward compatibility we need to preserve this
768 * preferred parenting to the gpio_chip parent field, if set.
769 */
770 if (chip->parent)
771 parent = chip->parent;
772 else
773 parent = &gdev->dev;
774
775 /* use chip->base for the ID; it's already known to be unique */
776 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), gdev,
777 gpiochip_groups, GPIOCHIP_NAME "%d",
778 chip->base);
779 if (IS_ERR(dev))
780 return PTR_ERR(dev);
781
782 mutex_lock(&sysfs_lock);
783 gdev->mockdev = dev;
784 mutex_unlock(&sysfs_lock);
785
786 return 0;
787 }
788
gpiochip_sysfs_unregister(struct gpio_device * gdev)789 void gpiochip_sysfs_unregister(struct gpio_device *gdev)
790 {
791 struct gpio_desc *desc;
792 struct gpio_chip *chip;
793
794 scoped_guard(mutex, &sysfs_lock) {
795 if (!gdev->mockdev)
796 return;
797
798 device_unregister(gdev->mockdev);
799
800 /* prevent further gpiod exports */
801 gdev->mockdev = NULL;
802 }
803
804 guard(srcu)(&gdev->srcu);
805
806 chip = srcu_dereference(gdev->chip, &gdev->srcu);
807 if (!chip)
808 return;
809
810 /* unregister gpiod class devices owned by sysfs */
811 for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) {
812 gpiod_unexport(desc);
813 gpiod_free(desc);
814 }
815 }
816
817 /*
818 * We're not really looking for a device - we just want to iterate over the
819 * list and call this callback for each GPIO device. This is why this function
820 * always returns 0.
821 */
gpiofind_sysfs_register(struct gpio_chip * gc,const void * data)822 static int gpiofind_sysfs_register(struct gpio_chip *gc, const void *data)
823 {
824 struct gpio_device *gdev = gc->gpiodev;
825 int ret;
826
827 if (gdev->mockdev)
828 return 0;
829
830 ret = gpiochip_sysfs_register(gdev);
831 if (ret)
832 chip_err(gc, "failed to register the sysfs entry: %d\n", ret);
833
834 return 0;
835 }
836
gpiolib_sysfs_init(void)837 static int __init gpiolib_sysfs_init(void)
838 {
839 int status;
840
841 status = class_register(&gpio_class);
842 if (status < 0)
843 return status;
844
845 /* Scan and register the gpio_chips which registered very
846 * early (e.g. before the class_register above was called).
847 *
848 * We run before arch_initcall() so chip->dev nodes can have
849 * registered, and so arch_initcall() can always gpiod_export().
850 */
851 (void)gpio_device_find(NULL, gpiofind_sysfs_register);
852
853 return 0;
854 }
855 postcore_initcall(gpiolib_sysfs_init);
856