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