blob: 5f2150b619a72127b11942d712599d053ff62676 [file] [log] [blame]
Alexandre Courbot0eb4c6c2014-07-01 14:45:15 +09001#include <linux/idr.h>
2#include <linux/mutex.h>
3#include <linux/device.h>
4#include <linux/sysfs.h>
5#include <linux/gpio/consumer.h>
6#include <linux/gpio/driver.h>
7#include <linux/interrupt.h>
8#include <linux/kdev_t.h>
9
10#include "gpiolib.h"
11
12static DEFINE_IDR(dirent_idr);
13
14
15/* lock protects against unexport_gpio() being called while
16 * sysfs files are active.
17 */
18static DEFINE_MUTEX(sysfs_lock);
19
20/*
21 * /sys/class/gpio/gpioN... only for GPIOs that are exported
22 * /direction
23 * * MAY BE OMITTED if kernel won't allow direction changes
24 * * is read/write as "in" or "out"
25 * * may also be written as "high" or "low", initializing
26 * output value as specified ("out" implies "low")
27 * /value
28 * * always readable, subject to hardware behavior
29 * * may be writable, as zero/nonzero
30 * /edge
31 * * configures behavior of poll(2) on /value
32 * * available only if pin can generate IRQs on input
33 * * is read/write as "none", "falling", "rising", or "both"
34 * /active_low
35 * * configures polarity of /value
36 * * is read/write as zero/nonzero
37 * * also affects existing and subsequent "falling" and "rising"
38 * /edge configuration
39 */
40
41static ssize_t gpio_direction_show(struct device *dev,
42 struct device_attribute *attr, char *buf)
43{
44 const struct gpio_desc *desc = dev_get_drvdata(dev);
45 ssize_t status;
46
47 mutex_lock(&sysfs_lock);
48
49 if (!test_bit(FLAG_EXPORT, &desc->flags)) {
50 status = -EIO;
51 } else {
52 gpiod_get_direction(desc);
53 status = sprintf(buf, "%s\n",
54 test_bit(FLAG_IS_OUT, &desc->flags)
55 ? "out" : "in");
56 }
57
58 mutex_unlock(&sysfs_lock);
59 return status;
60}
61
62static ssize_t gpio_direction_store(struct device *dev,
63 struct device_attribute *attr, const char *buf, size_t size)
64{
65 struct gpio_desc *desc = dev_get_drvdata(dev);
66 ssize_t status;
67
68 mutex_lock(&sysfs_lock);
69
70 if (!test_bit(FLAG_EXPORT, &desc->flags))
71 status = -EIO;
72 else if (sysfs_streq(buf, "high"))
73 status = gpiod_direction_output_raw(desc, 1);
74 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
75 status = gpiod_direction_output_raw(desc, 0);
76 else if (sysfs_streq(buf, "in"))
77 status = gpiod_direction_input(desc);
78 else
79 status = -EINVAL;
80
81 mutex_unlock(&sysfs_lock);
82 return status ? : size;
83}
84
85static /* const */ DEVICE_ATTR(direction, 0644,
86 gpio_direction_show, gpio_direction_store);
87
88static ssize_t gpio_value_show(struct device *dev,
89 struct device_attribute *attr, char *buf)
90{
91 struct gpio_desc *desc = dev_get_drvdata(dev);
92 ssize_t status;
93
94 mutex_lock(&sysfs_lock);
95
96 if (!test_bit(FLAG_EXPORT, &desc->flags))
97 status = -EIO;
98 else
99 status = sprintf(buf, "%d\n", gpiod_get_value_cansleep(desc));
100
101 mutex_unlock(&sysfs_lock);
102 return status;
103}
104
105static ssize_t gpio_value_store(struct device *dev,
106 struct device_attribute *attr, const char *buf, size_t size)
107{
108 struct gpio_desc *desc = dev_get_drvdata(dev);
109 ssize_t status;
110
111 mutex_lock(&sysfs_lock);
112
113 if (!test_bit(FLAG_EXPORT, &desc->flags))
114 status = -EIO;
115 else if (!test_bit(FLAG_IS_OUT, &desc->flags))
116 status = -EPERM;
117 else {
118 long value;
119
120 status = kstrtol(buf, 0, &value);
121 if (status == 0) {
122 gpiod_set_value_cansleep(desc, value);
123 status = size;
124 }
125 }
126
127 mutex_unlock(&sysfs_lock);
128 return status;
129}
130
131static const DEVICE_ATTR(value, 0644,
132 gpio_value_show, gpio_value_store);
133
134static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
135{
136 struct kernfs_node *value_sd = priv;
137
138 sysfs_notify_dirent(value_sd);
139 return IRQ_HANDLED;
140}
141
142static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev,
143 unsigned long gpio_flags)
144{
145 struct kernfs_node *value_sd;
146 unsigned long irq_flags;
147 int ret, irq, id;
148
149 if ((desc->flags & GPIO_TRIGGER_MASK) == gpio_flags)
150 return 0;
151
152 irq = gpiod_to_irq(desc);
153 if (irq < 0)
154 return -EIO;
155
156 id = desc->flags >> ID_SHIFT;
157 value_sd = idr_find(&dirent_idr, id);
158 if (value_sd)
159 free_irq(irq, value_sd);
160
161 desc->flags &= ~GPIO_TRIGGER_MASK;
162
163 if (!gpio_flags) {
Alexandre Courbotd74be6d2014-07-22 16:17:42 +0900164 gpio_unlock_as_irq(desc->chip, gpio_chip_hwgpio(desc));
Alexandre Courbot0eb4c6c2014-07-01 14:45:15 +0900165 ret = 0;
166 goto free_id;
167 }
168
169 irq_flags = IRQF_SHARED;
170 if (test_bit(FLAG_TRIG_FALL, &gpio_flags))
171 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
172 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
173 if (test_bit(FLAG_TRIG_RISE, &gpio_flags))
174 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
175 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
176
177 if (!value_sd) {
178 value_sd = sysfs_get_dirent(dev->kobj.sd, "value");
179 if (!value_sd) {
180 ret = -ENODEV;
181 goto err_out;
182 }
183
184 ret = idr_alloc(&dirent_idr, value_sd, 1, 0, GFP_KERNEL);
185 if (ret < 0)
186 goto free_sd;
187 id = ret;
188
189 desc->flags &= GPIO_FLAGS_MASK;
190 desc->flags |= (unsigned long)id << ID_SHIFT;
191
192 if (desc->flags >> ID_SHIFT != id) {
193 ret = -ERANGE;
194 goto free_id;
195 }
196 }
197
198 ret = request_any_context_irq(irq, gpio_sysfs_irq, irq_flags,
199 "gpiolib", value_sd);
200 if (ret < 0)
201 goto free_id;
202
Alexandre Courbotd74be6d2014-07-22 16:17:42 +0900203 ret = gpio_lock_as_irq(desc->chip, gpio_chip_hwgpio(desc));
Alexandre Courbot0eb4c6c2014-07-01 14:45:15 +0900204 if (ret < 0) {
205 gpiod_warn(desc, "failed to flag the GPIO for IRQ\n");
206 goto free_id;
207 }
208
209 desc->flags |= gpio_flags;
210 return 0;
211
212free_id:
213 idr_remove(&dirent_idr, id);
214 desc->flags &= GPIO_FLAGS_MASK;
215free_sd:
216 if (value_sd)
217 sysfs_put(value_sd);
218err_out:
219 return ret;
220}
221
222static const struct {
223 const char *name;
224 unsigned long flags;
225} trigger_types[] = {
226 { "none", 0 },
227 { "falling", BIT(FLAG_TRIG_FALL) },
228 { "rising", BIT(FLAG_TRIG_RISE) },
229 { "both", BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE) },
230};
231
232static ssize_t gpio_edge_show(struct device *dev,
233 struct device_attribute *attr, char *buf)
234{
235 const struct gpio_desc *desc = dev_get_drvdata(dev);
236 ssize_t status;
237
238 mutex_lock(&sysfs_lock);
239
240 if (!test_bit(FLAG_EXPORT, &desc->flags))
241 status = -EIO;
242 else {
243 int i;
244
245 status = 0;
246 for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
247 if ((desc->flags & GPIO_TRIGGER_MASK)
248 == trigger_types[i].flags) {
249 status = sprintf(buf, "%s\n",
250 trigger_types[i].name);
251 break;
252 }
253 }
254
255 mutex_unlock(&sysfs_lock);
256 return status;
257}
258
259static ssize_t gpio_edge_store(struct device *dev,
260 struct device_attribute *attr, const char *buf, size_t size)
261{
262 struct gpio_desc *desc = dev_get_drvdata(dev);
263 ssize_t status;
264 int i;
265
266 for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
267 if (sysfs_streq(trigger_types[i].name, buf))
268 goto found;
269 return -EINVAL;
270
271found:
272 mutex_lock(&sysfs_lock);
273
274 if (!test_bit(FLAG_EXPORT, &desc->flags))
275 status = -EIO;
276 else {
277 status = gpio_setup_irq(desc, dev, trigger_types[i].flags);
278 if (!status)
279 status = size;
280 }
281
282 mutex_unlock(&sysfs_lock);
283
284 return status;
285}
286
287static DEVICE_ATTR(edge, 0644, gpio_edge_show, gpio_edge_store);
288
289static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev,
290 int value)
291{
292 int status = 0;
293
294 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
295 return 0;
296
297 if (value)
298 set_bit(FLAG_ACTIVE_LOW, &desc->flags);
299 else
300 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
301
302 /* reconfigure poll(2) support if enabled on one edge only */
303 if (dev != NULL && (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
304 !!test_bit(FLAG_TRIG_FALL, &desc->flags))) {
305 unsigned long trigger_flags = desc->flags & GPIO_TRIGGER_MASK;
306
307 gpio_setup_irq(desc, dev, 0);
308 status = gpio_setup_irq(desc, dev, trigger_flags);
309 }
310
311 return status;
312}
313
314static ssize_t gpio_active_low_show(struct device *dev,
315 struct device_attribute *attr, char *buf)
316{
317 const struct gpio_desc *desc = dev_get_drvdata(dev);
318 ssize_t status;
319
320 mutex_lock(&sysfs_lock);
321
322 if (!test_bit(FLAG_EXPORT, &desc->flags))
323 status = -EIO;
324 else
325 status = sprintf(buf, "%d\n",
326 !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
327
328 mutex_unlock(&sysfs_lock);
329
330 return status;
331}
332
333static ssize_t gpio_active_low_store(struct device *dev,
334 struct device_attribute *attr, const char *buf, size_t size)
335{
336 struct gpio_desc *desc = dev_get_drvdata(dev);
337 ssize_t status;
338
339 mutex_lock(&sysfs_lock);
340
341 if (!test_bit(FLAG_EXPORT, &desc->flags)) {
342 status = -EIO;
343 } else {
344 long value;
345
346 status = kstrtol(buf, 0, &value);
347 if (status == 0)
348 status = sysfs_set_active_low(desc, dev, value != 0);
349 }
350
351 mutex_unlock(&sysfs_lock);
352
353 return status ? : size;
354}
355
356static const DEVICE_ATTR(active_low, 0644,
357 gpio_active_low_show, gpio_active_low_store);
358
359static const struct attribute *gpio_attrs[] = {
360 &dev_attr_value.attr,
361 &dev_attr_active_low.attr,
362 NULL,
363};
364
365static const struct attribute_group gpio_attr_group = {
366 .attrs = (struct attribute **) gpio_attrs,
367};
368
369/*
370 * /sys/class/gpio/gpiochipN/
371 * /base ... matching gpio_chip.base (N)
372 * /label ... matching gpio_chip.label
373 * /ngpio ... matching gpio_chip.ngpio
374 */
375
376static ssize_t chip_base_show(struct device *dev,
377 struct device_attribute *attr, char *buf)
378{
379 const struct gpio_chip *chip = dev_get_drvdata(dev);
380
381 return sprintf(buf, "%d\n", chip->base);
382}
383static DEVICE_ATTR(base, 0444, chip_base_show, NULL);
384
385static ssize_t chip_label_show(struct device *dev,
386 struct device_attribute *attr, char *buf)
387{
388 const struct gpio_chip *chip = dev_get_drvdata(dev);
389
390 return sprintf(buf, "%s\n", chip->label ? : "");
391}
392static DEVICE_ATTR(label, 0444, chip_label_show, NULL);
393
394static ssize_t chip_ngpio_show(struct device *dev,
395 struct device_attribute *attr, char *buf)
396{
397 const struct gpio_chip *chip = dev_get_drvdata(dev);
398
399 return sprintf(buf, "%u\n", chip->ngpio);
400}
401static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);
402
403static const struct attribute *gpiochip_attrs[] = {
404 &dev_attr_base.attr,
405 &dev_attr_label.attr,
406 &dev_attr_ngpio.attr,
407 NULL,
408};
409
410static const struct attribute_group gpiochip_attr_group = {
411 .attrs = (struct attribute **) gpiochip_attrs,
412};
413
414/*
415 * /sys/class/gpio/export ... write-only
416 * integer N ... number of GPIO to export (full access)
417 * /sys/class/gpio/unexport ... write-only
418 * integer N ... number of GPIO to unexport
419 */
420static ssize_t export_store(struct class *class,
421 struct class_attribute *attr,
422 const char *buf, size_t len)
423{
424 long gpio;
425 struct gpio_desc *desc;
426 int status;
427
428 status = kstrtol(buf, 0, &gpio);
429 if (status < 0)
430 goto done;
431
432 desc = gpio_to_desc(gpio);
433 /* reject invalid GPIOs */
434 if (!desc) {
435 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
436 return -EINVAL;
437 }
438
439 /* No extra locking here; FLAG_SYSFS just signifies that the
440 * request and export were done by on behalf of userspace, so
441 * they may be undone on its behalf too.
442 */
443
444 status = gpiod_request(desc, "sysfs");
445 if (status < 0) {
446 if (status == -EPROBE_DEFER)
447 status = -ENODEV;
448 goto done;
449 }
450 status = gpiod_export(desc, true);
451 if (status < 0)
452 gpiod_free(desc);
453 else
454 set_bit(FLAG_SYSFS, &desc->flags);
455
456done:
457 if (status)
458 pr_debug("%s: status %d\n", __func__, status);
459 return status ? : len;
460}
461
462static ssize_t unexport_store(struct class *class,
463 struct class_attribute *attr,
464 const char *buf, size_t len)
465{
466 long gpio;
467 struct gpio_desc *desc;
468 int status;
469
470 status = kstrtol(buf, 0, &gpio);
471 if (status < 0)
472 goto done;
473
474 desc = gpio_to_desc(gpio);
475 /* reject bogus commands (gpio_unexport ignores them) */
476 if (!desc) {
477 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
478 return -EINVAL;
479 }
480
481 status = -EINVAL;
482
483 /* No extra locking here; FLAG_SYSFS just signifies that the
484 * request and export were done by on behalf of userspace, so
485 * they may be undone on its behalf too.
486 */
487 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
488 status = 0;
489 gpiod_free(desc);
490 }
491done:
492 if (status)
493 pr_debug("%s: status %d\n", __func__, status);
494 return status ? : len;
495}
496
497static struct class_attribute gpio_class_attrs[] = {
498 __ATTR(export, 0200, NULL, export_store),
499 __ATTR(unexport, 0200, NULL, unexport_store),
500 __ATTR_NULL,
501};
502
503static struct class gpio_class = {
504 .name = "gpio",
505 .owner = THIS_MODULE,
506
507 .class_attrs = gpio_class_attrs,
508};
509
510
511/**
512 * gpiod_export - export a GPIO through sysfs
513 * @gpio: gpio to make available, already requested
514 * @direction_may_change: true if userspace may change gpio direction
515 * Context: arch_initcall or later
516 *
517 * When drivers want to make a GPIO accessible to userspace after they
518 * have requested it -- perhaps while debugging, or as part of their
519 * public interface -- they may use this routine. If the GPIO can
520 * change direction (some can't) and the caller allows it, userspace
521 * will see "direction" sysfs attribute which may be used to change
522 * the gpio's direction. A "value" attribute will always be provided.
523 *
524 * Returns zero on success, else an error.
525 */
526int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
527{
528 unsigned long flags;
529 int status;
530 const char *ioname = NULL;
531 struct device *dev;
532 int offset;
533
534 /* can't export until sysfs is available ... */
535 if (!gpio_class.p) {
536 pr_debug("%s: called too early!\n", __func__);
537 return -ENOENT;
538 }
539
540 if (!desc) {
541 pr_debug("%s: invalid gpio descriptor\n", __func__);
542 return -EINVAL;
543 }
544
545 mutex_lock(&sysfs_lock);
546
547 spin_lock_irqsave(&gpio_lock, flags);
548 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
549 test_bit(FLAG_EXPORT, &desc->flags)) {
550 spin_unlock_irqrestore(&gpio_lock, flags);
551 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
552 __func__,
553 test_bit(FLAG_REQUESTED, &desc->flags),
554 test_bit(FLAG_EXPORT, &desc->flags));
555 status = -EPERM;
556 goto fail_unlock;
557 }
558
559 if (!desc->chip->direction_input || !desc->chip->direction_output)
560 direction_may_change = false;
561 spin_unlock_irqrestore(&gpio_lock, flags);
562
563 offset = gpio_chip_hwgpio(desc);
564 if (desc->chip->names && desc->chip->names[offset])
565 ioname = desc->chip->names[offset];
566
567 dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
568 desc, ioname ? ioname : "gpio%u",
569 desc_to_gpio(desc));
570 if (IS_ERR(dev)) {
571 status = PTR_ERR(dev);
572 goto fail_unlock;
573 }
574
575 status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
576 if (status)
577 goto fail_unregister_device;
578
579 if (direction_may_change) {
580 status = device_create_file(dev, &dev_attr_direction);
581 if (status)
582 goto fail_unregister_device;
583 }
584
585 if (gpiod_to_irq(desc) >= 0 && (direction_may_change ||
586 !test_bit(FLAG_IS_OUT, &desc->flags))) {
587 status = device_create_file(dev, &dev_attr_edge);
588 if (status)
589 goto fail_unregister_device;
590 }
591
592 set_bit(FLAG_EXPORT, &desc->flags);
593 mutex_unlock(&sysfs_lock);
594 return 0;
595
596fail_unregister_device:
597 device_unregister(dev);
598fail_unlock:
599 mutex_unlock(&sysfs_lock);
600 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
601 return status;
602}
603EXPORT_SYMBOL_GPL(gpiod_export);
604
605static int match_export(struct device *dev, const void *data)
606{
607 return dev_get_drvdata(dev) == data;
608}
609
610/**
611 * gpiod_export_link - create a sysfs link to an exported GPIO node
612 * @dev: device under which to create symlink
613 * @name: name of the symlink
614 * @gpio: gpio to create symlink to, already exported
615 *
616 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
617 * node. Caller is responsible for unlinking.
618 *
619 * Returns zero on success, else an error.
620 */
621int gpiod_export_link(struct device *dev, const char *name,
622 struct gpio_desc *desc)
623{
624 int status = -EINVAL;
625
626 if (!desc) {
627 pr_warn("%s: invalid GPIO\n", __func__);
628 return -EINVAL;
629 }
630
631 mutex_lock(&sysfs_lock);
632
633 if (test_bit(FLAG_EXPORT, &desc->flags)) {
634 struct device *tdev;
635
636 tdev = class_find_device(&gpio_class, NULL, desc, match_export);
637 if (tdev != NULL) {
638 status = sysfs_create_link(&dev->kobj, &tdev->kobj,
639 name);
640 } else {
641 status = -ENODEV;
642 }
643 }
644
645 mutex_unlock(&sysfs_lock);
646
647 if (status)
648 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
649
650 return status;
651}
652EXPORT_SYMBOL_GPL(gpiod_export_link);
653
654/**
655 * gpiod_sysfs_set_active_low - set the polarity of gpio sysfs value
656 * @gpio: gpio to change
657 * @value: non-zero to use active low, i.e. inverted values
658 *
659 * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
660 * The GPIO does not have to be exported yet. If poll(2) support has
661 * been enabled for either rising or falling edge, it will be
662 * reconfigured to follow the new polarity.
663 *
664 * Returns zero on success, else an error.
665 */
666int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
667{
668 struct device *dev = NULL;
669 int status = -EINVAL;
670
671 if (!desc) {
672 pr_warn("%s: invalid GPIO\n", __func__);
673 return -EINVAL;
674 }
675
676 mutex_lock(&sysfs_lock);
677
678 if (test_bit(FLAG_EXPORT, &desc->flags)) {
679 dev = class_find_device(&gpio_class, NULL, desc, match_export);
680 if (dev == NULL) {
681 status = -ENODEV;
682 goto unlock;
683 }
684 }
685
686 status = sysfs_set_active_low(desc, dev, value);
687
688unlock:
689 mutex_unlock(&sysfs_lock);
690
691 if (status)
692 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
693
694 return status;
695}
696EXPORT_SYMBOL_GPL(gpiod_sysfs_set_active_low);
697
698/**
699 * gpiod_unexport - reverse effect of gpio_export()
700 * @gpio: gpio to make unavailable
701 *
702 * This is implicit on gpio_free().
703 */
704void gpiod_unexport(struct gpio_desc *desc)
705{
706 int status = 0;
707 struct device *dev = NULL;
708
709 if (!desc) {
710 pr_warn("%s: invalid GPIO\n", __func__);
711 return;
712 }
713
714 mutex_lock(&sysfs_lock);
715
716 if (test_bit(FLAG_EXPORT, &desc->flags)) {
717
718 dev = class_find_device(&gpio_class, NULL, desc, match_export);
719 if (dev) {
720 gpio_setup_irq(desc, dev, 0);
721 clear_bit(FLAG_EXPORT, &desc->flags);
722 } else
723 status = -ENODEV;
724 }
725
726 mutex_unlock(&sysfs_lock);
727
728 if (dev) {
729 device_unregister(dev);
730 put_device(dev);
731 }
732
733 if (status)
734 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
735}
736EXPORT_SYMBOL_GPL(gpiod_unexport);
737
738int gpiochip_export(struct gpio_chip *chip)
739{
740 int status;
741 struct device *dev;
742
743 /* Many systems register gpio chips for SOC support very early,
744 * before driver model support is available. In those cases we
745 * export this later, in gpiolib_sysfs_init() ... here we just
746 * verify that _some_ field of gpio_class got initialized.
747 */
748 if (!gpio_class.p)
749 return 0;
750
751 /* use chip->base for the ID; it's already known to be unique */
752 mutex_lock(&sysfs_lock);
753 dev = device_create(&gpio_class, chip->dev, MKDEV(0, 0), chip,
754 "gpiochip%d", chip->base);
755 if (!IS_ERR(dev)) {
756 status = sysfs_create_group(&dev->kobj,
757 &gpiochip_attr_group);
758 } else
759 status = PTR_ERR(dev);
760 chip->exported = (status == 0);
761 mutex_unlock(&sysfs_lock);
762
Alexandre Courbot14141a92014-07-22 16:17:40 +0900763 if (status)
Alexandre Courbot0eb4c6c2014-07-01 14:45:15 +0900764 chip_dbg(chip, "%s: status %d\n", __func__, status);
Alexandre Courbot0eb4c6c2014-07-01 14:45:15 +0900765
766 return status;
767}
768
769void gpiochip_unexport(struct gpio_chip *chip)
770{
771 int status;
772 struct device *dev;
773
774 mutex_lock(&sysfs_lock);
775 dev = class_find_device(&gpio_class, NULL, chip, match_export);
776 if (dev) {
777 put_device(dev);
778 device_unregister(dev);
779 chip->exported = false;
780 status = 0;
781 } else
782 status = -ENODEV;
783 mutex_unlock(&sysfs_lock);
784
785 if (status)
786 chip_dbg(chip, "%s: status %d\n", __func__, status);
787}
788
789static int __init gpiolib_sysfs_init(void)
790{
791 int status;
792 unsigned long flags;
793 struct gpio_chip *chip;
794
795 status = class_register(&gpio_class);
796 if (status < 0)
797 return status;
798
799 /* Scan and register the gpio_chips which registered very
800 * early (e.g. before the class_register above was called).
801 *
802 * We run before arch_initcall() so chip->dev nodes can have
803 * registered, and so arch_initcall() can always gpio_export().
804 */
805 spin_lock_irqsave(&gpio_lock, flags);
806 list_for_each_entry(chip, &gpio_chips, list) {
Alexandre Courbot7fd834a2014-07-23 23:56:53 +0900807 if (chip->exported)
Alexandre Courbot0eb4c6c2014-07-01 14:45:15 +0900808 continue;
809
Alexandre Courbot14141a92014-07-22 16:17:40 +0900810 /*
811 * TODO we yield gpio_lock here because gpiochip_export()
812 * acquires a mutex. This is unsafe and needs to be fixed.
813 *
814 * Also it would be nice to use gpiochip_find() here so we
815 * can keep gpio_chips local to gpiolib.c, but the yield of
816 * gpio_lock prevents us from doing this.
817 */
Alexandre Courbot0eb4c6c2014-07-01 14:45:15 +0900818 spin_unlock_irqrestore(&gpio_lock, flags);
819 status = gpiochip_export(chip);
820 spin_lock_irqsave(&gpio_lock, flags);
821 }
822 spin_unlock_irqrestore(&gpio_lock, flags);
823
824
825 return status;
826}
827postcore_initcall(gpiolib_sysfs_init);