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
21 struct 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 */
36 static 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
direction_show(struct device * dev,struct device_attribute * attr,char * buf)59 static 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 = sprintf(buf, "%s\n",
70 test_bit(FLAG_IS_OUT, &desc->flags)
71 ? "out" : "in");
72
73 mutex_unlock(&data->mutex);
74
75 return status;
76 }
77
direction_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)78 static ssize_t direction_store(struct device *dev,
79 struct device_attribute *attr, const char *buf, size_t size)
80 {
81 struct gpiod_data *data = dev_get_drvdata(dev);
82 struct gpio_desc *desc = data->desc;
83 ssize_t status;
84
85 mutex_lock(&data->mutex);
86
87 if (sysfs_streq(buf, "high"))
88 status = gpiod_direction_output_raw(desc, 1);
89 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
90 status = gpiod_direction_output_raw(desc, 0);
91 else if (sysfs_streq(buf, "in"))
92 status = gpiod_direction_input(desc);
93 else
94 status = -EINVAL;
95
96 mutex_unlock(&data->mutex);
97
98 return status ? : size;
99 }
100 static DEVICE_ATTR_RW(direction);
101
value_show(struct device * dev,struct device_attribute * attr,char * buf)102 static ssize_t value_show(struct device *dev,
103 struct device_attribute *attr, char *buf)
104 {
105 struct gpiod_data *data = dev_get_drvdata(dev);
106 struct gpio_desc *desc = data->desc;
107 ssize_t status;
108
109 mutex_lock(&data->mutex);
110
111 status = gpiod_get_value_cansleep(desc);
112 if (status < 0)
113 goto err;
114
115 buf[0] = '0' + status;
116 buf[1] = '\n';
117 status = 2;
118 err:
119 mutex_unlock(&data->mutex);
120
121 return status;
122 }
123
value_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)124 static ssize_t value_store(struct device *dev,
125 struct device_attribute *attr, const char *buf, size_t size)
126 {
127 struct gpiod_data *data = dev_get_drvdata(dev);
128 struct gpio_desc *desc = data->desc;
129 ssize_t status = 0;
130
131 mutex_lock(&data->mutex);
132
133 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
134 status = -EPERM;
135 } else {
136 long value;
137
138 if (size <= 2 && isdigit(buf[0]) &&
139 (size == 1 || buf[1] == '\n'))
140 value = buf[0] - '0';
141 else
142 status = kstrtol(buf, 0, &value);
143 if (status == 0) {
144 gpiod_set_value_cansleep(desc, value);
145 status = size;
146 }
147 }
148
149 mutex_unlock(&data->mutex);
150
151 return status;
152 }
153 static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
154
gpio_sysfs_irq(int irq,void * priv)155 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
156 {
157 struct gpiod_data *data = priv;
158
159 sysfs_notify_dirent(data->value_kn);
160
161 return IRQ_HANDLED;
162 }
163
164 /* Caller holds gpiod-data mutex. */
gpio_sysfs_request_irq(struct device * dev,unsigned char flags)165 static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
166 {
167 struct gpiod_data *data = dev_get_drvdata(dev);
168 struct gpio_desc *desc = data->desc;
169 unsigned long irq_flags;
170 int ret;
171
172 data->irq = gpiod_to_irq(desc);
173 if (data->irq < 0)
174 return -EIO;
175
176 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
177 if (!data->value_kn)
178 return -ENODEV;
179
180 irq_flags = IRQF_SHARED;
181 if (flags & GPIO_IRQF_TRIGGER_FALLING)
182 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
183 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
184 if (flags & GPIO_IRQF_TRIGGER_RISING)
185 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
186 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
187
188 /*
189 * FIXME: This should be done in the irq_request_resources callback
190 * when the irq is requested, but a few drivers currently fail
191 * to do so.
192 *
193 * Remove this redundant call (along with the corresponding
194 * unlock) when those drivers have been fixed.
195 */
196 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
197 if (ret < 0)
198 goto err_put_kn;
199
200 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
201 "gpiolib", data);
202 if (ret < 0)
203 goto err_unlock;
204
205 data->irq_flags = flags;
206
207 return 0;
208
209 err_unlock:
210 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
211 err_put_kn:
212 sysfs_put(data->value_kn);
213
214 return ret;
215 }
216
217 /*
218 * Caller holds gpiod-data mutex (unless called after class-device
219 * deregistration).
220 */
gpio_sysfs_free_irq(struct device * dev)221 static void gpio_sysfs_free_irq(struct device *dev)
222 {
223 struct gpiod_data *data = dev_get_drvdata(dev);
224 struct gpio_desc *desc = data->desc;
225
226 data->irq_flags = 0;
227 free_irq(data->irq, data);
228 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
229 sysfs_put(data->value_kn);
230 }
231
232 static const struct {
233 const char *name;
234 unsigned char flags;
235 } trigger_types[] = {
236 { "none", 0 },
237 { "falling", GPIO_IRQF_TRIGGER_FALLING },
238 { "rising", GPIO_IRQF_TRIGGER_RISING },
239 { "both", GPIO_IRQF_TRIGGER_BOTH },
240 };
241
edge_show(struct device * dev,struct device_attribute * attr,char * buf)242 static ssize_t edge_show(struct device *dev,
243 struct device_attribute *attr, char *buf)
244 {
245 struct gpiod_data *data = dev_get_drvdata(dev);
246 ssize_t status = 0;
247 int i;
248
249 mutex_lock(&data->mutex);
250
251 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
252 if (data->irq_flags == trigger_types[i].flags) {
253 status = sprintf(buf, "%s\n", trigger_types[i].name);
254 break;
255 }
256 }
257
258 mutex_unlock(&data->mutex);
259
260 return status;
261 }
262
edge_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)263 static ssize_t edge_store(struct device *dev,
264 struct device_attribute *attr, const char *buf, size_t size)
265 {
266 struct gpiod_data *data = dev_get_drvdata(dev);
267 unsigned char flags;
268 ssize_t status = size;
269 int i;
270
271 for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
272 if (sysfs_streq(trigger_types[i].name, buf))
273 break;
274 }
275
276 if (i == ARRAY_SIZE(trigger_types))
277 return -EINVAL;
278
279 flags = trigger_types[i].flags;
280
281 mutex_lock(&data->mutex);
282
283 if (flags == data->irq_flags) {
284 status = size;
285 goto out_unlock;
286 }
287
288 if (data->irq_flags)
289 gpio_sysfs_free_irq(dev);
290
291 if (flags) {
292 status = gpio_sysfs_request_irq(dev, flags);
293 if (!status)
294 status = size;
295 }
296
297 out_unlock:
298 mutex_unlock(&data->mutex);
299
300 return status;
301 }
302 static DEVICE_ATTR_RW(edge);
303
304 /* Caller holds gpiod-data mutex. */
gpio_sysfs_set_active_low(struct device * dev,int value)305 static int gpio_sysfs_set_active_low(struct device *dev, int value)
306 {
307 struct gpiod_data *data = dev_get_drvdata(dev);
308 struct gpio_desc *desc = data->desc;
309 int status = 0;
310 unsigned int flags = data->irq_flags;
311
312 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
313 return 0;
314
315 if (value)
316 set_bit(FLAG_ACTIVE_LOW, &desc->flags);
317 else
318 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
319
320 /* reconfigure poll(2) support if enabled on one edge only */
321 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
322 flags == GPIO_IRQF_TRIGGER_RISING) {
323 gpio_sysfs_free_irq(dev);
324 status = gpio_sysfs_request_irq(dev, flags);
325 }
326
327 return status;
328 }
329
active_low_show(struct device * dev,struct device_attribute * attr,char * buf)330 static ssize_t active_low_show(struct device *dev,
331 struct device_attribute *attr, char *buf)
332 {
333 struct gpiod_data *data = dev_get_drvdata(dev);
334 struct gpio_desc *desc = data->desc;
335 ssize_t status;
336
337 mutex_lock(&data->mutex);
338
339 status = sprintf(buf, "%d\n",
340 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
341
342 mutex_unlock(&data->mutex);
343
344 return status;
345 }
346
active_low_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)347 static ssize_t active_low_store(struct device *dev,
348 struct device_attribute *attr, const char *buf, size_t size)
349 {
350 struct gpiod_data *data = dev_get_drvdata(dev);
351 ssize_t status;
352 long value;
353
354 mutex_lock(&data->mutex);
355
356 status = kstrtol(buf, 0, &value);
357 if (status == 0)
358 status = gpio_sysfs_set_active_low(dev, value);
359
360 mutex_unlock(&data->mutex);
361
362 return status ? : size;
363 }
364 static DEVICE_ATTR_RW(active_low);
365
gpio_is_visible(struct kobject * kobj,struct attribute * attr,int n)366 static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
367 int n)
368 {
369 struct device *dev = kobj_to_dev(kobj);
370 struct gpiod_data *data = dev_get_drvdata(dev);
371 struct gpio_desc *desc = data->desc;
372 umode_t mode = attr->mode;
373 bool show_direction = data->direction_can_change;
374
375 if (attr == &dev_attr_direction.attr) {
376 if (!show_direction)
377 mode = 0;
378 } else if (attr == &dev_attr_edge.attr) {
379 if (gpiod_to_irq(desc) < 0)
380 mode = 0;
381 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
382 mode = 0;
383 }
384
385 return mode;
386 }
387
388 static struct attribute *gpio_attrs[] = {
389 &dev_attr_direction.attr,
390 &dev_attr_edge.attr,
391 &dev_attr_value.attr,
392 &dev_attr_active_low.attr,
393 NULL,
394 };
395
396 static const struct attribute_group gpio_group = {
397 .attrs = gpio_attrs,
398 .is_visible = gpio_is_visible,
399 };
400
401 static const struct attribute_group *gpio_groups[] = {
402 &gpio_group,
403 NULL
404 };
405
406 /*
407 * /sys/class/gpio/gpiochipN/
408 * /base ... matching gpio_chip.base (N)
409 * /label ... matching gpio_chip.label
410 * /ngpio ... matching gpio_chip.ngpio
411 */
412
base_show(struct device * dev,struct device_attribute * attr,char * buf)413 static ssize_t base_show(struct device *dev,
414 struct device_attribute *attr, char *buf)
415 {
416 const struct gpio_chip *chip = dev_get_drvdata(dev);
417
418 return sprintf(buf, "%d\n", chip->base);
419 }
420 static DEVICE_ATTR_RO(base);
421
label_show(struct device * dev,struct device_attribute * attr,char * buf)422 static ssize_t label_show(struct device *dev,
423 struct device_attribute *attr, char *buf)
424 {
425 const struct gpio_chip *chip = dev_get_drvdata(dev);
426
427 return sprintf(buf, "%s\n", chip->label ? : "");
428 }
429 static DEVICE_ATTR_RO(label);
430
ngpio_show(struct device * dev,struct device_attribute * attr,char * buf)431 static ssize_t ngpio_show(struct device *dev,
432 struct device_attribute *attr, char *buf)
433 {
434 const struct gpio_chip *chip = dev_get_drvdata(dev);
435
436 return sprintf(buf, "%u\n", chip->ngpio);
437 }
438 static DEVICE_ATTR_RO(ngpio);
439
440 static struct attribute *gpiochip_attrs[] = {
441 &dev_attr_base.attr,
442 &dev_attr_label.attr,
443 &dev_attr_ngpio.attr,
444 NULL,
445 };
446 ATTRIBUTE_GROUPS(gpiochip);
447
448 /*
449 * /sys/class/gpio/export ... write-only
450 * integer N ... number of GPIO to export (full access)
451 * /sys/class/gpio/unexport ... write-only
452 * integer N ... number of GPIO to unexport
453 */
export_store(struct class * class,struct class_attribute * attr,const char * buf,size_t len)454 static ssize_t export_store(struct class *class,
455 struct class_attribute *attr,
456 const char *buf, size_t len)
457 {
458 long gpio;
459 struct gpio_desc *desc;
460 int status;
461 struct gpio_chip *gc;
462 int offset;
463
464 status = kstrtol(buf, 0, &gpio);
465 if (status < 0)
466 goto done;
467
468 desc = gpio_to_desc(gpio);
469 /* reject invalid GPIOs */
470 if (!desc) {
471 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
472 return -EINVAL;
473 }
474 gc = desc->gdev->chip;
475 offset = gpio_chip_hwgpio(desc);
476 if (!gpiochip_line_is_valid(gc, offset)) {
477 pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
478 return -EINVAL;
479 }
480
481 /* No extra locking here; FLAG_SYSFS just signifies that the
482 * request and export were done by on behalf of userspace, so
483 * they may be undone on its behalf too.
484 */
485
486 status = gpiod_request(desc, "sysfs");
487 if (status < 0) {
488 if (status == -EPROBE_DEFER)
489 status = -ENODEV;
490 goto done;
491 }
492
493 status = gpiod_set_transitory(desc, false);
494 if (status) {
495 gpiod_free(desc);
496 goto done;
497 }
498
499 status = gpiod_export(desc, true);
500 if (status < 0)
501 gpiod_free(desc);
502 else
503 set_bit(FLAG_SYSFS, &desc->flags);
504
505 done:
506 if (status)
507 pr_debug("%s: status %d\n", __func__, status);
508 return status ? : len;
509 }
510 static CLASS_ATTR_WO(export);
511
unexport_store(struct class * class,struct class_attribute * attr,const char * buf,size_t len)512 static ssize_t unexport_store(struct class *class,
513 struct class_attribute *attr,
514 const char *buf, size_t len)
515 {
516 long gpio;
517 struct gpio_desc *desc;
518 int status;
519
520 status = kstrtol(buf, 0, &gpio);
521 if (status < 0)
522 goto done;
523
524 desc = gpio_to_desc(gpio);
525 /* reject bogus commands (gpio_unexport ignores them) */
526 if (!desc) {
527 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
528 return -EINVAL;
529 }
530
531 status = -EINVAL;
532
533 /* No extra locking here; FLAG_SYSFS just signifies that the
534 * request and export were done by on behalf of userspace, so
535 * they may be undone on its behalf too.
536 */
537 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
538 status = 0;
539 gpiod_free(desc);
540 }
541 done:
542 if (status)
543 pr_debug("%s: status %d\n", __func__, status);
544 return status ? : len;
545 }
546 static CLASS_ATTR_WO(unexport);
547
548 static struct attribute *gpio_class_attrs[] = {
549 &class_attr_export.attr,
550 &class_attr_unexport.attr,
551 NULL,
552 };
553 ATTRIBUTE_GROUPS(gpio_class);
554
555 static struct class gpio_class = {
556 .name = "gpio",
557 .owner = THIS_MODULE,
558
559 .class_groups = gpio_class_groups,
560 };
561
562
563 /**
564 * gpiod_export - export a GPIO through sysfs
565 * @desc: GPIO to make available, already requested
566 * @direction_may_change: true if userspace may change GPIO direction
567 * Context: arch_initcall or later
568 *
569 * When drivers want to make a GPIO accessible to userspace after they
570 * have requested it -- perhaps while debugging, or as part of their
571 * public interface -- they may use this routine. If the GPIO can
572 * change direction (some can't) and the caller allows it, userspace
573 * will see "direction" sysfs attribute which may be used to change
574 * the gpio's direction. A "value" attribute will always be provided.
575 *
576 * Returns zero on success, else an error.
577 */
gpiod_export(struct gpio_desc * desc,bool direction_may_change)578 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
579 {
580 struct gpio_chip *chip;
581 struct gpio_device *gdev;
582 struct gpiod_data *data;
583 unsigned long flags;
584 int status;
585 const char *ioname = NULL;
586 struct device *dev;
587 int offset;
588
589 /* can't export until sysfs is available ... */
590 if (!gpio_class.p) {
591 pr_debug("%s: called too early!\n", __func__);
592 return -ENOENT;
593 }
594
595 if (!desc) {
596 pr_debug("%s: invalid gpio descriptor\n", __func__);
597 return -EINVAL;
598 }
599
600 gdev = desc->gdev;
601 chip = gdev->chip;
602
603 mutex_lock(&sysfs_lock);
604
605 /* check if chip is being removed */
606 if (!chip || !gdev->mockdev) {
607 status = -ENODEV;
608 goto err_unlock;
609 }
610
611 spin_lock_irqsave(&gpio_lock, flags);
612 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
613 test_bit(FLAG_EXPORT, &desc->flags)) {
614 spin_unlock_irqrestore(&gpio_lock, flags);
615 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
616 __func__,
617 test_bit(FLAG_REQUESTED, &desc->flags),
618 test_bit(FLAG_EXPORT, &desc->flags));
619 status = -EPERM;
620 goto err_unlock;
621 }
622 spin_unlock_irqrestore(&gpio_lock, flags);
623
624 data = kzalloc(sizeof(*data), GFP_KERNEL);
625 if (!data) {
626 status = -ENOMEM;
627 goto err_unlock;
628 }
629
630 data->desc = desc;
631 mutex_init(&data->mutex);
632 if (chip->direction_input && chip->direction_output)
633 data->direction_can_change = direction_may_change;
634 else
635 data->direction_can_change = false;
636
637 offset = gpio_chip_hwgpio(desc);
638 if (chip->names && chip->names[offset])
639 ioname = chip->names[offset];
640
641 dev = device_create_with_groups(&gpio_class, &gdev->dev,
642 MKDEV(0, 0), data, gpio_groups,
643 ioname ? ioname : "gpio%u",
644 desc_to_gpio(desc));
645 if (IS_ERR(dev)) {
646 status = PTR_ERR(dev);
647 goto err_free_data;
648 }
649
650 set_bit(FLAG_EXPORT, &desc->flags);
651 mutex_unlock(&sysfs_lock);
652 return 0;
653
654 err_free_data:
655 kfree(data);
656 err_unlock:
657 mutex_unlock(&sysfs_lock);
658 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
659 return status;
660 }
661 EXPORT_SYMBOL_GPL(gpiod_export);
662
match_export(struct device * dev,const void * desc)663 static int match_export(struct device *dev, const void *desc)
664 {
665 struct gpiod_data *data = dev_get_drvdata(dev);
666
667 return data->desc == desc;
668 }
669
670 /**
671 * gpiod_export_link - create a sysfs link to an exported GPIO node
672 * @dev: device under which to create symlink
673 * @name: name of the symlink
674 * @desc: GPIO to create symlink to, already exported
675 *
676 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
677 * node. Caller is responsible for unlinking.
678 *
679 * Returns zero on success, else an error.
680 */
gpiod_export_link(struct device * dev,const char * name,struct gpio_desc * desc)681 int gpiod_export_link(struct device *dev, const char *name,
682 struct gpio_desc *desc)
683 {
684 struct device *cdev;
685 int ret;
686
687 if (!desc) {
688 pr_warn("%s: invalid GPIO\n", __func__);
689 return -EINVAL;
690 }
691
692 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
693 if (!cdev)
694 return -ENODEV;
695
696 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
697 put_device(cdev);
698
699 return ret;
700 }
701 EXPORT_SYMBOL_GPL(gpiod_export_link);
702
703 /**
704 * gpiod_unexport - reverse effect of gpiod_export()
705 * @desc: GPIO to make unavailable
706 *
707 * This is implicit on gpiod_free().
708 */
gpiod_unexport(struct gpio_desc * desc)709 void gpiod_unexport(struct gpio_desc *desc)
710 {
711 struct gpiod_data *data;
712 struct device *dev;
713
714 if (!desc) {
715 pr_warn("%s: invalid GPIO\n", __func__);
716 return;
717 }
718
719 mutex_lock(&sysfs_lock);
720
721 if (!test_bit(FLAG_EXPORT, &desc->flags))
722 goto err_unlock;
723
724 dev = class_find_device(&gpio_class, NULL, desc, match_export);
725 if (!dev)
726 goto err_unlock;
727
728 data = dev_get_drvdata(dev);
729
730 clear_bit(FLAG_EXPORT, &desc->flags);
731
732 device_unregister(dev);
733
734 /*
735 * Release irq after deregistration to prevent race with edge_store.
736 */
737 if (data->irq_flags)
738 gpio_sysfs_free_irq(dev);
739
740 mutex_unlock(&sysfs_lock);
741
742 put_device(dev);
743 kfree(data);
744
745 return;
746
747 err_unlock:
748 mutex_unlock(&sysfs_lock);
749 }
750 EXPORT_SYMBOL_GPL(gpiod_unexport);
751
gpiochip_sysfs_register(struct gpio_device * gdev)752 int gpiochip_sysfs_register(struct gpio_device *gdev)
753 {
754 struct device *dev;
755 struct device *parent;
756 struct gpio_chip *chip = gdev->chip;
757
758 /*
759 * Many systems add gpio chips for SOC support very early,
760 * before driver model support is available. In those cases we
761 * register later, in gpiolib_sysfs_init() ... here we just
762 * verify that _some_ field of gpio_class got initialized.
763 */
764 if (!gpio_class.p)
765 return 0;
766
767 /*
768 * For sysfs backward compatibility we need to preserve this
769 * preferred parenting to the gpio_chip parent field, if set.
770 */
771 if (chip->parent)
772 parent = chip->parent;
773 else
774 parent = &gdev->dev;
775
776 /* use chip->base for the ID; it's already known to be unique */
777 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
778 gpiochip_groups, GPIOCHIP_NAME "%d",
779 chip->base);
780 if (IS_ERR(dev))
781 return PTR_ERR(dev);
782
783 mutex_lock(&sysfs_lock);
784 gdev->mockdev = dev;
785 mutex_unlock(&sysfs_lock);
786
787 return 0;
788 }
789
gpiochip_sysfs_unregister(struct gpio_device * gdev)790 void gpiochip_sysfs_unregister(struct gpio_device *gdev)
791 {
792 struct gpio_desc *desc;
793 struct gpio_chip *chip = gdev->chip;
794 unsigned int i;
795
796 if (!gdev->mockdev)
797 return;
798
799 device_unregister(gdev->mockdev);
800
801 /* prevent further gpiod exports */
802 mutex_lock(&sysfs_lock);
803 gdev->mockdev = NULL;
804 mutex_unlock(&sysfs_lock);
805
806 /* unregister gpiod class devices owned by sysfs */
807 for (i = 0; i < chip->ngpio; i++) {
808 desc = &gdev->descs[i];
809 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
810 gpiod_free(desc);
811 }
812 }
813
gpiolib_sysfs_init(void)814 static int __init gpiolib_sysfs_init(void)
815 {
816 int status;
817 unsigned long flags;
818 struct gpio_device *gdev;
819
820 status = class_register(&gpio_class);
821 if (status < 0)
822 return status;
823
824 /* Scan and register the gpio_chips which registered very
825 * early (e.g. before the class_register above was called).
826 *
827 * We run before arch_initcall() so chip->dev nodes can have
828 * registered, and so arch_initcall() can always gpio_export().
829 */
830 spin_lock_irqsave(&gpio_lock, flags);
831 list_for_each_entry(gdev, &gpio_devices, list) {
832 if (gdev->mockdev)
833 continue;
834
835 /*
836 * TODO we yield gpio_lock here because
837 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
838 * and needs to be fixed.
839 *
840 * Also it would be nice to use gpiochip_find() here so we
841 * can keep gpio_chips local to gpiolib.c, but the yield of
842 * gpio_lock prevents us from doing this.
843 */
844 spin_unlock_irqrestore(&gpio_lock, flags);
845 status = gpiochip_sysfs_register(gdev);
846 spin_lock_irqsave(&gpio_lock, flags);
847 }
848 spin_unlock_irqrestore(&gpio_lock, flags);
849
850 return status;
851 }
852 postcore_initcall(gpiolib_sysfs_init);
853