1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/bitops.h>
4 #include <linux/device.h>
5 #include <linux/idr.h>
6 #include <linux/init.h>
7 #include <linux/interrupt.h>
8 #include <linux/kdev_t.h>
9 #include <linux/kstrtox.h>
10 #include <linux/list.h>
11 #include <linux/mutex.h>
12 #include <linux/printk.h>
13 #include <linux/slab.h>
14 #include <linux/spinlock.h>
15 #include <linux/string.h>
16 #include <linux/sysfs.h>
17 #include <linux/types.h>
18
19 #include <linux/gpio/consumer.h>
20 #include <linux/gpio/driver.h>
21
22 #include "gpiolib.h"
23 #include "gpiolib-sysfs.h"
24
25 struct kernfs_node;
26
27 #define GPIO_IRQF_TRIGGER_NONE 0
28 #define GPIO_IRQF_TRIGGER_FALLING BIT(0)
29 #define GPIO_IRQF_TRIGGER_RISING BIT(1)
30 #define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
31 GPIO_IRQF_TRIGGER_RISING)
32
33 struct gpiod_data {
34 struct gpio_desc *desc;
35
36 struct mutex mutex;
37 struct kernfs_node *value_kn;
38 int irq;
39 unsigned char irq_flags;
40
41 bool direction_can_change;
42 };
43
44 /*
45 * Lock to serialise gpiod export and unexport, and prevent re-export of
46 * gpiod whose chip is being unregistered.
47 */
48 static DEFINE_MUTEX(sysfs_lock);
49
50 /*
51 * /sys/class/gpio/gpioN... only for GPIOs that are exported
52 * /direction
53 * * MAY BE OMITTED if kernel won't allow direction changes
54 * * is read/write as "in" or "out"
55 * * may also be written as "high" or "low", initializing
56 * output value as specified ("out" implies "low")
57 * /value
58 * * always readable, subject to hardware behavior
59 * * may be writable, as zero/nonzero
60 * /edge
61 * * configures behavior of poll(2) on /value
62 * * available only if pin can generate IRQs on input
63 * * is read/write as "none", "falling", "rising", or "both"
64 * /active_low
65 * * configures polarity of /value
66 * * is read/write as zero/nonzero
67 * * also affects existing and subsequent "falling" and "rising"
68 * /edge configuration
69 */
70
direction_show(struct device * dev,struct device_attribute * attr,char * buf)71 static ssize_t direction_show(struct device *dev,
72 struct device_attribute *attr, char *buf)
73 {
74 struct gpiod_data *data = dev_get_drvdata(dev);
75 struct gpio_desc *desc = data->desc;
76 int value;
77
78 mutex_lock(&data->mutex);
79
80 gpiod_get_direction(desc);
81 value = !!test_bit(FLAG_IS_OUT, &desc->flags);
82
83 mutex_unlock(&data->mutex);
84
85 return sysfs_emit(buf, "%s\n", value ? "out" : "in");
86 }
87
direction_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)88 static ssize_t direction_store(struct device *dev,
89 struct device_attribute *attr, const char *buf, size_t size)
90 {
91 struct gpiod_data *data = dev_get_drvdata(dev);
92 struct gpio_desc *desc = data->desc;
93 ssize_t status;
94
95 mutex_lock(&data->mutex);
96
97 if (sysfs_streq(buf, "high"))
98 status = gpiod_direction_output_raw(desc, 1);
99 else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
100 status = gpiod_direction_output_raw(desc, 0);
101 else if (sysfs_streq(buf, "in"))
102 status = gpiod_direction_input(desc);
103 else
104 status = -EINVAL;
105
106 mutex_unlock(&data->mutex);
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 mutex_lock(&data->mutex);
120
121 status = gpiod_get_value_cansleep(desc);
122
123 mutex_unlock(&data->mutex);
124
125 if (status < 0)
126 return status;
127
128 return sysfs_emit(buf, "%zd\n", status);
129 }
130
value_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)131 static ssize_t value_store(struct device *dev,
132 struct device_attribute *attr, const char *buf, size_t size)
133 {
134 struct gpiod_data *data = dev_get_drvdata(dev);
135 struct gpio_desc *desc = data->desc;
136 ssize_t status;
137 long value;
138
139 status = kstrtol(buf, 0, &value);
140
141 mutex_lock(&data->mutex);
142
143 if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
144 status = -EPERM;
145 } else if (status == 0) {
146 gpiod_set_value_cansleep(desc, value);
147 status = size;
148 }
149
150 mutex_unlock(&data->mutex);
151
152 return status;
153 }
154 static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
155
gpio_sysfs_irq(int irq,void * priv)156 static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
157 {
158 struct gpiod_data *data = priv;
159
160 sysfs_notify_dirent(data->value_kn);
161
162 return IRQ_HANDLED;
163 }
164
165 /* Caller holds gpiod-data mutex. */
gpio_sysfs_request_irq(struct device * dev,unsigned char flags)166 static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
167 {
168 struct gpiod_data *data = dev_get_drvdata(dev);
169 struct gpio_desc *desc = data->desc;
170 unsigned long irq_flags;
171 int ret;
172
173 data->irq = gpiod_to_irq(desc);
174 if (data->irq < 0)
175 return -EIO;
176
177 data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
178 if (!data->value_kn)
179 return -ENODEV;
180
181 irq_flags = IRQF_SHARED;
182 if (flags & GPIO_IRQF_TRIGGER_FALLING)
183 irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
184 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
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
189 /*
190 * FIXME: This should be done in the irq_request_resources callback
191 * when the irq is requested, but a few drivers currently fail
192 * to do so.
193 *
194 * Remove this redundant call (along with the corresponding
195 * unlock) when those drivers have been fixed.
196 */
197 ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
198 if (ret < 0)
199 goto err_put_kn;
200
201 ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
202 "gpiolib", data);
203 if (ret < 0)
204 goto err_unlock;
205
206 data->irq_flags = flags;
207
208 return 0;
209
210 err_unlock:
211 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
212 err_put_kn:
213 sysfs_put(data->value_kn);
214
215 return ret;
216 }
217
218 /*
219 * Caller holds gpiod-data mutex (unless called after class-device
220 * deregistration).
221 */
gpio_sysfs_free_irq(struct device * dev)222 static void gpio_sysfs_free_irq(struct device *dev)
223 {
224 struct gpiod_data *data = dev_get_drvdata(dev);
225 struct gpio_desc *desc = data->desc;
226
227 data->irq_flags = 0;
228 free_irq(data->irq, data);
229 gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
230 sysfs_put(data->value_kn);
231 }
232
233 static const char * const trigger_names[] = {
234 [GPIO_IRQF_TRIGGER_NONE] = "none",
235 [GPIO_IRQF_TRIGGER_FALLING] = "falling",
236 [GPIO_IRQF_TRIGGER_RISING] = "rising",
237 [GPIO_IRQF_TRIGGER_BOTH] = "both",
238 };
239
edge_show(struct device * dev,struct device_attribute * attr,char * buf)240 static ssize_t edge_show(struct device *dev,
241 struct device_attribute *attr, char *buf)
242 {
243 struct gpiod_data *data = dev_get_drvdata(dev);
244 int flags;
245
246 mutex_lock(&data->mutex);
247
248 flags = data->irq_flags;
249
250 mutex_unlock(&data->mutex);
251
252 if (flags >= ARRAY_SIZE(trigger_names))
253 return 0;
254
255 return sysfs_emit(buf, "%s\n", trigger_names[flags]);
256 }
257
edge_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)258 static ssize_t edge_store(struct device *dev,
259 struct device_attribute *attr, const char *buf, size_t size)
260 {
261 struct gpiod_data *data = dev_get_drvdata(dev);
262 ssize_t status = size;
263 int flags;
264
265 flags = sysfs_match_string(trigger_names, buf);
266 if (flags < 0)
267 return flags;
268
269 mutex_lock(&data->mutex);
270
271 if (flags == data->irq_flags) {
272 status = size;
273 goto out_unlock;
274 }
275
276 if (data->irq_flags)
277 gpio_sysfs_free_irq(dev);
278
279 if (flags) {
280 status = gpio_sysfs_request_irq(dev, flags);
281 if (!status)
282 status = size;
283 }
284
285 out_unlock:
286 mutex_unlock(&data->mutex);
287
288 return status;
289 }
290 static DEVICE_ATTR_RW(edge);
291
292 /* Caller holds gpiod-data mutex. */
gpio_sysfs_set_active_low(struct device * dev,int value)293 static int gpio_sysfs_set_active_low(struct device *dev, int value)
294 {
295 struct gpiod_data *data = dev_get_drvdata(dev);
296 struct gpio_desc *desc = data->desc;
297 int status = 0;
298 unsigned int flags = data->irq_flags;
299
300 if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
301 return 0;
302
303 assign_bit(FLAG_ACTIVE_LOW, &desc->flags, value);
304
305 /* reconfigure poll(2) support if enabled on one edge only */
306 if (flags == GPIO_IRQF_TRIGGER_FALLING ||
307 flags == GPIO_IRQF_TRIGGER_RISING) {
308 gpio_sysfs_free_irq(dev);
309 status = gpio_sysfs_request_irq(dev, flags);
310 }
311
312 return status;
313 }
314
active_low_show(struct device * dev,struct device_attribute * attr,char * buf)315 static ssize_t active_low_show(struct device *dev,
316 struct device_attribute *attr, char *buf)
317 {
318 struct gpiod_data *data = dev_get_drvdata(dev);
319 struct gpio_desc *desc = data->desc;
320 int value;
321
322 mutex_lock(&data->mutex);
323
324 value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
325
326 mutex_unlock(&data->mutex);
327
328 return sysfs_emit(buf, "%d\n", value);
329 }
330
active_low_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)331 static ssize_t active_low_store(struct device *dev,
332 struct device_attribute *attr, const char *buf, size_t size)
333 {
334 struct gpiod_data *data = dev_get_drvdata(dev);
335 ssize_t status;
336 long value;
337
338 status = kstrtol(buf, 0, &value);
339 if (status)
340 return status;
341
342 mutex_lock(&data->mutex);
343
344 status = gpio_sysfs_set_active_low(dev, value);
345
346 mutex_unlock(&data->mutex);
347
348 return status ? : size;
349 }
350 static DEVICE_ATTR_RW(active_low);
351
gpio_is_visible(struct kobject * kobj,struct attribute * attr,int n)352 static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
353 int n)
354 {
355 struct device *dev = kobj_to_dev(kobj);
356 struct gpiod_data *data = dev_get_drvdata(dev);
357 struct gpio_desc *desc = data->desc;
358 umode_t mode = attr->mode;
359 bool show_direction = data->direction_can_change;
360
361 if (attr == &dev_attr_direction.attr) {
362 if (!show_direction)
363 mode = 0;
364 } else if (attr == &dev_attr_edge.attr) {
365 if (gpiod_to_irq(desc) < 0)
366 mode = 0;
367 if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
368 mode = 0;
369 }
370
371 return mode;
372 }
373
374 static struct attribute *gpio_attrs[] = {
375 &dev_attr_direction.attr,
376 &dev_attr_edge.attr,
377 &dev_attr_value.attr,
378 &dev_attr_active_low.attr,
379 NULL,
380 };
381
382 static const struct attribute_group gpio_group = {
383 .attrs = gpio_attrs,
384 .is_visible = gpio_is_visible,
385 };
386
387 static const struct attribute_group *gpio_groups[] = {
388 &gpio_group,
389 NULL
390 };
391
392 /*
393 * /sys/class/gpio/gpiochipN/
394 * /base ... matching gpio_chip.base (N)
395 * /label ... matching gpio_chip.label
396 * /ngpio ... matching gpio_chip.ngpio
397 */
398
base_show(struct device * dev,struct device_attribute * attr,char * buf)399 static ssize_t base_show(struct device *dev,
400 struct device_attribute *attr, char *buf)
401 {
402 const struct gpio_chip *chip = dev_get_drvdata(dev);
403
404 return sysfs_emit(buf, "%d\n", chip->base);
405 }
406 static DEVICE_ATTR_RO(base);
407
label_show(struct device * dev,struct device_attribute * attr,char * buf)408 static ssize_t label_show(struct device *dev,
409 struct device_attribute *attr, char *buf)
410 {
411 const struct gpio_chip *chip = dev_get_drvdata(dev);
412
413 return sysfs_emit(buf, "%s\n", chip->label ?: "");
414 }
415 static DEVICE_ATTR_RO(label);
416
ngpio_show(struct device * dev,struct device_attribute * attr,char * buf)417 static ssize_t ngpio_show(struct device *dev,
418 struct device_attribute *attr, char *buf)
419 {
420 const struct gpio_chip *chip = dev_get_drvdata(dev);
421
422 return sysfs_emit(buf, "%u\n", chip->ngpio);
423 }
424 static DEVICE_ATTR_RO(ngpio);
425
426 static struct attribute *gpiochip_attrs[] = {
427 &dev_attr_base.attr,
428 &dev_attr_label.attr,
429 &dev_attr_ngpio.attr,
430 NULL,
431 };
432 ATTRIBUTE_GROUPS(gpiochip);
433
434 /*
435 * /sys/class/gpio/export ... write-only
436 * integer N ... number of GPIO to export (full access)
437 * /sys/class/gpio/unexport ... write-only
438 * integer N ... number of GPIO to unexport
439 */
export_store(const struct class * class,const struct class_attribute * attr,const char * buf,size_t len)440 static ssize_t export_store(const struct class *class,
441 const struct class_attribute *attr,
442 const char *buf, size_t len)
443 {
444 long gpio;
445 struct gpio_desc *desc;
446 int status;
447 struct gpio_chip *gc;
448 int offset;
449
450 status = kstrtol(buf, 0, &gpio);
451 if (status < 0)
452 goto done;
453
454 desc = gpio_to_desc(gpio);
455 /* reject invalid GPIOs */
456 if (!desc) {
457 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
458 return -EINVAL;
459 }
460 gc = desc->gdev->chip;
461 offset = gpio_chip_hwgpio(desc);
462 if (!gpiochip_line_is_valid(gc, offset)) {
463 pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
464 return -EINVAL;
465 }
466
467 /* No extra locking here; FLAG_SYSFS just signifies that the
468 * request and export were done by on behalf of userspace, so
469 * they may be undone on its behalf too.
470 */
471
472 status = gpiod_request_user(desc, "sysfs");
473 if (status)
474 goto done;
475
476 status = gpiod_set_transitory(desc, false);
477 if (status) {
478 gpiod_free(desc);
479 goto done;
480 }
481
482 status = gpiod_export(desc, true);
483 if (status < 0)
484 gpiod_free(desc);
485 else
486 set_bit(FLAG_SYSFS, &desc->flags);
487
488 done:
489 if (status)
490 pr_debug("%s: status %d\n", __func__, status);
491 return status ? : len;
492 }
493 static CLASS_ATTR_WO(export);
494
unexport_store(const struct class * class,const struct class_attribute * attr,const char * buf,size_t len)495 static ssize_t unexport_store(const struct class *class,
496 const struct class_attribute *attr,
497 const char *buf, size_t len)
498 {
499 long gpio;
500 struct gpio_desc *desc;
501 int status;
502
503 status = kstrtol(buf, 0, &gpio);
504 if (status < 0)
505 goto done;
506
507 desc = gpio_to_desc(gpio);
508 /* reject bogus commands (gpiod_unexport() ignores them) */
509 if (!desc) {
510 pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
511 return -EINVAL;
512 }
513
514 status = -EINVAL;
515
516 /* No extra locking here; FLAG_SYSFS just signifies that the
517 * request and export were done by on behalf of userspace, so
518 * they may be undone on its behalf too.
519 */
520 if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
521 gpiod_unexport(desc);
522 gpiod_free(desc);
523 status = 0;
524 }
525 done:
526 if (status)
527 pr_debug("%s: status %d\n", __func__, status);
528 return status ? : len;
529 }
530 static CLASS_ATTR_WO(unexport);
531
532 static struct attribute *gpio_class_attrs[] = {
533 &class_attr_export.attr,
534 &class_attr_unexport.attr,
535 NULL,
536 };
537 ATTRIBUTE_GROUPS(gpio_class);
538
539 static struct class gpio_class = {
540 .name = "gpio",
541 .class_groups = gpio_class_groups,
542 };
543
544
545 /**
546 * gpiod_export - export a GPIO through sysfs
547 * @desc: GPIO to make available, already requested
548 * @direction_may_change: true if userspace may change GPIO direction
549 * Context: arch_initcall or later
550 *
551 * When drivers want to make a GPIO accessible to userspace after they
552 * have requested it -- perhaps while debugging, or as part of their
553 * public interface -- they may use this routine. If the GPIO can
554 * change direction (some can't) and the caller allows it, userspace
555 * will see "direction" sysfs attribute which may be used to change
556 * the gpio's direction. A "value" attribute will always be provided.
557 *
558 * Returns zero on success, else an error.
559 */
gpiod_export(struct gpio_desc * desc,bool direction_may_change)560 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
561 {
562 struct gpio_chip *chip;
563 struct gpio_device *gdev;
564 struct gpiod_data *data;
565 unsigned long flags;
566 int status;
567 const char *ioname = NULL;
568 struct device *dev;
569 int offset;
570
571 /* can't export until sysfs is available ... */
572 if (!class_is_registered(&gpio_class)) {
573 pr_debug("%s: called too early!\n", __func__);
574 return -ENOENT;
575 }
576
577 if (!desc) {
578 pr_debug("%s: invalid gpio descriptor\n", __func__);
579 return -EINVAL;
580 }
581
582 gdev = desc->gdev;
583 chip = gdev->chip;
584
585 mutex_lock(&sysfs_lock);
586
587 /* check if chip is being removed */
588 if (!chip || !gdev->mockdev) {
589 status = -ENODEV;
590 goto err_unlock;
591 }
592
593 spin_lock_irqsave(&gpio_lock, flags);
594 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
595 test_bit(FLAG_EXPORT, &desc->flags)) {
596 spin_unlock_irqrestore(&gpio_lock, flags);
597 gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
598 __func__,
599 test_bit(FLAG_REQUESTED, &desc->flags),
600 test_bit(FLAG_EXPORT, &desc->flags));
601 status = -EPERM;
602 goto err_unlock;
603 }
604 spin_unlock_irqrestore(&gpio_lock, flags);
605
606 data = kzalloc(sizeof(*data), GFP_KERNEL);
607 if (!data) {
608 status = -ENOMEM;
609 goto err_unlock;
610 }
611
612 data->desc = desc;
613 mutex_init(&data->mutex);
614 if (chip->direction_input && chip->direction_output)
615 data->direction_can_change = direction_may_change;
616 else
617 data->direction_can_change = false;
618
619 offset = gpio_chip_hwgpio(desc);
620 if (chip->names && chip->names[offset])
621 ioname = chip->names[offset];
622
623 dev = device_create_with_groups(&gpio_class, &gdev->dev,
624 MKDEV(0, 0), data, gpio_groups,
625 ioname ? ioname : "gpio%u",
626 desc_to_gpio(desc));
627 if (IS_ERR(dev)) {
628 status = PTR_ERR(dev);
629 goto err_free_data;
630 }
631
632 set_bit(FLAG_EXPORT, &desc->flags);
633 mutex_unlock(&sysfs_lock);
634 return 0;
635
636 err_free_data:
637 kfree(data);
638 err_unlock:
639 mutex_unlock(&sysfs_lock);
640 gpiod_dbg(desc, "%s: status %d\n", __func__, status);
641 return status;
642 }
643 EXPORT_SYMBOL_GPL(gpiod_export);
644
match_export(struct device * dev,const void * desc)645 static int match_export(struct device *dev, const void *desc)
646 {
647 struct gpiod_data *data = dev_get_drvdata(dev);
648
649 return data->desc == desc;
650 }
651
652 /**
653 * gpiod_export_link - create a sysfs link to an exported GPIO node
654 * @dev: device under which to create symlink
655 * @name: name of the symlink
656 * @desc: GPIO to create symlink to, already exported
657 *
658 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
659 * node. Caller is responsible for unlinking.
660 *
661 * Returns zero on success, else an error.
662 */
gpiod_export_link(struct device * dev,const char * name,struct gpio_desc * desc)663 int gpiod_export_link(struct device *dev, const char *name,
664 struct gpio_desc *desc)
665 {
666 struct device *cdev;
667 int ret;
668
669 if (!desc) {
670 pr_warn("%s: invalid GPIO\n", __func__);
671 return -EINVAL;
672 }
673
674 cdev = class_find_device(&gpio_class, NULL, desc, match_export);
675 if (!cdev)
676 return -ENODEV;
677
678 ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
679 put_device(cdev);
680
681 return ret;
682 }
683 EXPORT_SYMBOL_GPL(gpiod_export_link);
684
685 /**
686 * gpiod_unexport - reverse effect of gpiod_export()
687 * @desc: GPIO to make unavailable
688 *
689 * This is implicit on gpiod_free().
690 */
gpiod_unexport(struct gpio_desc * desc)691 void gpiod_unexport(struct gpio_desc *desc)
692 {
693 struct gpiod_data *data;
694 struct device *dev;
695
696 if (!desc) {
697 pr_warn("%s: invalid GPIO\n", __func__);
698 return;
699 }
700
701 mutex_lock(&sysfs_lock);
702
703 if (!test_bit(FLAG_EXPORT, &desc->flags))
704 goto err_unlock;
705
706 dev = class_find_device(&gpio_class, NULL, desc, match_export);
707 if (!dev)
708 goto err_unlock;
709
710 data = dev_get_drvdata(dev);
711
712 clear_bit(FLAG_EXPORT, &desc->flags);
713
714 device_unregister(dev);
715
716 /*
717 * Release irq after deregistration to prevent race with edge_store.
718 */
719 if (data->irq_flags)
720 gpio_sysfs_free_irq(dev);
721
722 mutex_unlock(&sysfs_lock);
723
724 put_device(dev);
725 kfree(data);
726
727 return;
728
729 err_unlock:
730 mutex_unlock(&sysfs_lock);
731 }
732 EXPORT_SYMBOL_GPL(gpiod_unexport);
733
gpiochip_sysfs_register(struct gpio_device * gdev)734 int gpiochip_sysfs_register(struct gpio_device *gdev)
735 {
736 struct device *dev;
737 struct device *parent;
738 struct gpio_chip *chip = gdev->chip;
739
740 /*
741 * Many systems add gpio chips for SOC support very early,
742 * before driver model support is available. In those cases we
743 * register later, in gpiolib_sysfs_init() ... here we just
744 * verify that _some_ field of gpio_class got initialized.
745 */
746 if (!class_is_registered(&gpio_class))
747 return 0;
748
749 /*
750 * For sysfs backward compatibility we need to preserve this
751 * preferred parenting to the gpio_chip parent field, if set.
752 */
753 if (chip->parent)
754 parent = chip->parent;
755 else
756 parent = &gdev->dev;
757
758 /* use chip->base for the ID; it's already known to be unique */
759 dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
760 gpiochip_groups, GPIOCHIP_NAME "%d",
761 chip->base);
762 if (IS_ERR(dev))
763 return PTR_ERR(dev);
764
765 mutex_lock(&sysfs_lock);
766 gdev->mockdev = dev;
767 mutex_unlock(&sysfs_lock);
768
769 return 0;
770 }
771
gpiochip_sysfs_unregister(struct gpio_device * gdev)772 void gpiochip_sysfs_unregister(struct gpio_device *gdev)
773 {
774 struct gpio_desc *desc;
775 struct gpio_chip *chip = gdev->chip;
776
777 if (!gdev->mockdev)
778 return;
779
780 device_unregister(gdev->mockdev);
781
782 /* prevent further gpiod exports */
783 mutex_lock(&sysfs_lock);
784 gdev->mockdev = NULL;
785 mutex_unlock(&sysfs_lock);
786
787 /* unregister gpiod class devices owned by sysfs */
788 for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) {
789 gpiod_unexport(desc);
790 gpiod_free(desc);
791 }
792 }
793
gpiolib_sysfs_init(void)794 static int __init gpiolib_sysfs_init(void)
795 {
796 int status;
797 unsigned long flags;
798 struct gpio_device *gdev;
799
800 status = class_register(&gpio_class);
801 if (status < 0)
802 return status;
803
804 /* Scan and register the gpio_chips which registered very
805 * early (e.g. before the class_register above was called).
806 *
807 * We run before arch_initcall() so chip->dev nodes can have
808 * registered, and so arch_initcall() can always gpiod_export().
809 */
810 spin_lock_irqsave(&gpio_lock, flags);
811 list_for_each_entry(gdev, &gpio_devices, list) {
812 if (gdev->mockdev)
813 continue;
814
815 /*
816 * TODO we yield gpio_lock here because
817 * gpiochip_sysfs_register() acquires a mutex. This is unsafe
818 * and needs to be fixed.
819 *
820 * Also it would be nice to use gpio_device_find() here so we
821 * can keep gpio_chips local to gpiolib.c, but the yield of
822 * gpio_lock prevents us from doing this.
823 */
824 spin_unlock_irqrestore(&gpio_lock, flags);
825 status = gpiochip_sysfs_register(gdev);
826 spin_lock_irqsave(&gpio_lock, flags);
827 }
828 spin_unlock_irqrestore(&gpio_lock, flags);
829
830 return status;
831 }
832 postcore_initcall(gpiolib_sysfs_init);
833