1 | // SPDX-License-Identifier: GPL-2.0 |
2 | |
3 | #include <linux/bitops.h> |
4 | #include <linux/cleanup.h> |
5 | #include <linux/device.h> |
6 | #include <linux/idr.h> |
7 | #include <linux/init.h> |
8 | #include <linux/interrupt.h> |
9 | #include <linux/kdev_t.h> |
10 | #include <linux/kstrtox.h> |
11 | #include <linux/list.h> |
12 | #include <linux/mutex.h> |
13 | #include <linux/printk.h> |
14 | #include <linux/slab.h> |
15 | #include <linux/spinlock.h> |
16 | #include <linux/string.h> |
17 | #include <linux/srcu.h> |
18 | #include <linux/sysfs.h> |
19 | #include <linux/types.h> |
20 | |
21 | #include <linux/gpio/consumer.h> |
22 | #include <linux/gpio/driver.h> |
23 | |
24 | #include "gpiolib.h" |
25 | #include "gpiolib-sysfs.h" |
26 | |
27 | struct kernfs_node; |
28 | |
29 | #define GPIO_IRQF_TRIGGER_NONE 0 |
30 | #define GPIO_IRQF_TRIGGER_FALLING BIT(0) |
31 | #define GPIO_IRQF_TRIGGER_RISING BIT(1) |
32 | #define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \ |
33 | GPIO_IRQF_TRIGGER_RISING) |
34 | |
35 | struct gpiod_data { |
36 | struct gpio_desc *desc; |
37 | |
38 | struct mutex mutex; |
39 | struct kernfs_node *value_kn; |
40 | int irq; |
41 | unsigned char irq_flags; |
42 | |
43 | bool direction_can_change; |
44 | }; |
45 | |
46 | /* |
47 | * Lock to serialise gpiod export and unexport, and prevent re-export of |
48 | * gpiod whose chip is being unregistered. |
49 | */ |
50 | static DEFINE_MUTEX(sysfs_lock); |
51 | |
52 | /* |
53 | * /sys/class/gpio/gpioN... only for GPIOs that are exported |
54 | * /direction |
55 | * * MAY BE OMITTED if kernel won't allow direction changes |
56 | * * is read/write as "in" or "out" |
57 | * * may also be written as "high" or "low", initializing |
58 | * output value as specified ("out" implies "low") |
59 | * /value |
60 | * * always readable, subject to hardware behavior |
61 | * * may be writable, as zero/nonzero |
62 | * /edge |
63 | * * configures behavior of poll(2) on /value |
64 | * * available only if pin can generate IRQs on input |
65 | * * is read/write as "none", "falling", "rising", or "both" |
66 | * /active_low |
67 | * * configures polarity of /value |
68 | * * is read/write as zero/nonzero |
69 | * * also affects existing and subsequent "falling" and "rising" |
70 | * /edge configuration |
71 | */ |
72 | |
73 | static ssize_t direction_show(struct device *dev, |
74 | struct device_attribute *attr, char *buf) |
75 | { |
76 | struct gpiod_data *data = dev_get_drvdata(dev); |
77 | struct gpio_desc *desc = data->desc; |
78 | int value; |
79 | |
80 | mutex_lock(&data->mutex); |
81 | |
82 | gpiod_get_direction(desc); |
83 | value = !!test_bit(FLAG_IS_OUT, &desc->flags); |
84 | |
85 | mutex_unlock(lock: &data->mutex); |
86 | |
87 | return sysfs_emit(buf, fmt: "%s\n" , value ? "out" : "in" ); |
88 | } |
89 | |
90 | static ssize_t direction_store(struct device *dev, |
91 | struct device_attribute *attr, const char *buf, size_t size) |
92 | { |
93 | struct gpiod_data *data = dev_get_drvdata(dev); |
94 | struct gpio_desc *desc = data->desc; |
95 | ssize_t status; |
96 | |
97 | mutex_lock(&data->mutex); |
98 | |
99 | if (sysfs_streq(s1: buf, s2: "high" )) |
100 | status = gpiod_direction_output_raw(desc, value: 1); |
101 | else if (sysfs_streq(s1: buf, s2: "out" ) || sysfs_streq(s1: buf, s2: "low" )) |
102 | status = gpiod_direction_output_raw(desc, value: 0); |
103 | else if (sysfs_streq(s1: buf, s2: "in" )) |
104 | status = gpiod_direction_input(desc); |
105 | else |
106 | status = -EINVAL; |
107 | |
108 | mutex_unlock(lock: &data->mutex); |
109 | |
110 | return status ? : size; |
111 | } |
112 | static DEVICE_ATTR_RW(direction); |
113 | |
114 | static ssize_t value_show(struct device *dev, |
115 | struct device_attribute *attr, char *buf) |
116 | { |
117 | struct gpiod_data *data = dev_get_drvdata(dev); |
118 | struct gpio_desc *desc = data->desc; |
119 | ssize_t status; |
120 | |
121 | mutex_lock(&data->mutex); |
122 | |
123 | status = gpiod_get_value_cansleep(desc); |
124 | |
125 | mutex_unlock(lock: &data->mutex); |
126 | |
127 | if (status < 0) |
128 | return status; |
129 | |
130 | return sysfs_emit(buf, fmt: "%zd\n" , status); |
131 | } |
132 | |
133 | static ssize_t value_store(struct device *dev, |
134 | struct device_attribute *attr, const char *buf, size_t size) |
135 | { |
136 | struct gpiod_data *data = dev_get_drvdata(dev); |
137 | struct gpio_desc *desc = data->desc; |
138 | ssize_t status; |
139 | long value; |
140 | |
141 | status = kstrtol(s: buf, base: 0, res: &value); |
142 | |
143 | mutex_lock(&data->mutex); |
144 | |
145 | if (!test_bit(FLAG_IS_OUT, &desc->flags)) { |
146 | status = -EPERM; |
147 | } else if (status == 0) { |
148 | gpiod_set_value_cansleep(desc, value); |
149 | status = size; |
150 | } |
151 | |
152 | mutex_unlock(lock: &data->mutex); |
153 | |
154 | return status; |
155 | } |
156 | static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store); |
157 | |
158 | static irqreturn_t gpio_sysfs_irq(int irq, void *priv) |
159 | { |
160 | struct gpiod_data *data = priv; |
161 | |
162 | sysfs_notify_dirent(kn: data->value_kn); |
163 | |
164 | return IRQ_HANDLED; |
165 | } |
166 | |
167 | /* Caller holds gpiod-data mutex. */ |
168 | static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags) |
169 | { |
170 | struct gpiod_data *data = dev_get_drvdata(dev); |
171 | struct gpio_desc *desc = data->desc; |
172 | unsigned long irq_flags; |
173 | int ret; |
174 | |
175 | CLASS(gpio_chip_guard, guard)(desc); |
176 | if (!guard.gc) |
177 | return -ENODEV; |
178 | |
179 | data->irq = gpiod_to_irq(desc); |
180 | if (data->irq < 0) |
181 | return -EIO; |
182 | |
183 | data->value_kn = sysfs_get_dirent(parent: dev->kobj.sd, name: "value" ); |
184 | if (!data->value_kn) |
185 | return -ENODEV; |
186 | |
187 | irq_flags = IRQF_SHARED; |
188 | if (flags & GPIO_IRQF_TRIGGER_FALLING) |
189 | irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ? |
190 | IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING; |
191 | if (flags & GPIO_IRQF_TRIGGER_RISING) |
192 | irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ? |
193 | IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING; |
194 | |
195 | /* |
196 | * FIXME: This should be done in the irq_request_resources callback |
197 | * when the irq is requested, but a few drivers currently fail |
198 | * to do so. |
199 | * |
200 | * Remove this redundant call (along with the corresponding |
201 | * unlock) when those drivers have been fixed. |
202 | */ |
203 | ret = gpiochip_lock_as_irq(gc: guard.gc, offset: gpio_chip_hwgpio(desc)); |
204 | if (ret < 0) |
205 | goto err_put_kn; |
206 | |
207 | ret = request_any_context_irq(irq: data->irq, handler: gpio_sysfs_irq, flags: irq_flags, |
208 | name: "gpiolib" , dev_id: data); |
209 | if (ret < 0) |
210 | goto err_unlock; |
211 | |
212 | data->irq_flags = flags; |
213 | |
214 | return 0; |
215 | |
216 | err_unlock: |
217 | gpiochip_unlock_as_irq(gc: guard.gc, offset: gpio_chip_hwgpio(desc)); |
218 | err_put_kn: |
219 | sysfs_put(kn: data->value_kn); |
220 | |
221 | return ret; |
222 | } |
223 | |
224 | /* |
225 | * Caller holds gpiod-data mutex (unless called after class-device |
226 | * deregistration). |
227 | */ |
228 | static void gpio_sysfs_free_irq(struct device *dev) |
229 | { |
230 | struct gpiod_data *data = dev_get_drvdata(dev); |
231 | struct gpio_desc *desc = data->desc; |
232 | |
233 | CLASS(gpio_chip_guard, guard)(desc); |
234 | if (!guard.gc) |
235 | return; |
236 | |
237 | data->irq_flags = 0; |
238 | free_irq(data->irq, data); |
239 | gpiochip_unlock_as_irq(gc: guard.gc, offset: gpio_chip_hwgpio(desc)); |
240 | sysfs_put(kn: 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 | |
250 | static ssize_t edge_show(struct device *dev, |
251 | struct device_attribute *attr, char *buf) |
252 | { |
253 | struct gpiod_data *data = dev_get_drvdata(dev); |
254 | int flags; |
255 | |
256 | mutex_lock(&data->mutex); |
257 | |
258 | flags = data->irq_flags; |
259 | |
260 | mutex_unlock(lock: &data->mutex); |
261 | |
262 | if (flags >= ARRAY_SIZE(trigger_names)) |
263 | return 0; |
264 | |
265 | return sysfs_emit(buf, fmt: "%s\n" , trigger_names[flags]); |
266 | } |
267 | |
268 | static ssize_t edge_store(struct device *dev, |
269 | struct device_attribute *attr, const char *buf, size_t size) |
270 | { |
271 | struct gpiod_data *data = dev_get_drvdata(dev); |
272 | ssize_t status = size; |
273 | int flags; |
274 | |
275 | flags = sysfs_match_string(trigger_names, buf); |
276 | if (flags < 0) |
277 | return flags; |
278 | |
279 | mutex_lock(&data->mutex); |
280 | |
281 | if (flags == data->irq_flags) { |
282 | status = size; |
283 | goto out_unlock; |
284 | } |
285 | |
286 | if (data->irq_flags) |
287 | gpio_sysfs_free_irq(dev); |
288 | |
289 | if (flags) { |
290 | status = gpio_sysfs_request_irq(dev, flags); |
291 | if (!status) |
292 | status = size; |
293 | } |
294 | |
295 | out_unlock: |
296 | mutex_unlock(lock: &data->mutex); |
297 | |
298 | return status; |
299 | } |
300 | static DEVICE_ATTR_RW(edge); |
301 | |
302 | /* Caller holds gpiod-data mutex. */ |
303 | static int gpio_sysfs_set_active_low(struct device *dev, int value) |
304 | { |
305 | struct gpiod_data *data = dev_get_drvdata(dev); |
306 | unsigned int flags = data->irq_flags; |
307 | struct gpio_desc *desc = data->desc; |
308 | int status = 0; |
309 | |
310 | |
311 | if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value) |
312 | return 0; |
313 | |
314 | assign_bit(FLAG_ACTIVE_LOW, addr: &desc->flags, value); |
315 | |
316 | /* reconfigure poll(2) support if enabled on one edge only */ |
317 | if (flags == GPIO_IRQF_TRIGGER_FALLING || |
318 | flags == GPIO_IRQF_TRIGGER_RISING) { |
319 | gpio_sysfs_free_irq(dev); |
320 | status = gpio_sysfs_request_irq(dev, flags); |
321 | } |
322 | |
323 | return status; |
324 | } |
325 | |
326 | static ssize_t active_low_show(struct device *dev, |
327 | struct device_attribute *attr, char *buf) |
328 | { |
329 | struct gpiod_data *data = dev_get_drvdata(dev); |
330 | struct gpio_desc *desc = data->desc; |
331 | int value; |
332 | |
333 | mutex_lock(&data->mutex); |
334 | |
335 | value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags); |
336 | |
337 | mutex_unlock(lock: &data->mutex); |
338 | |
339 | return sysfs_emit(buf, fmt: "%d\n" , value); |
340 | } |
341 | |
342 | static ssize_t active_low_store(struct device *dev, |
343 | struct device_attribute *attr, const char *buf, size_t size) |
344 | { |
345 | struct gpiod_data *data = dev_get_drvdata(dev); |
346 | ssize_t status; |
347 | long value; |
348 | |
349 | status = kstrtol(s: buf, base: 0, res: &value); |
350 | if (status) |
351 | return status; |
352 | |
353 | mutex_lock(&data->mutex); |
354 | |
355 | status = gpio_sysfs_set_active_low(dev, value); |
356 | |
357 | mutex_unlock(lock: &data->mutex); |
358 | |
359 | return status ? : size; |
360 | } |
361 | static DEVICE_ATTR_RW(active_low); |
362 | |
363 | static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr, |
364 | int n) |
365 | { |
366 | struct device *dev = kobj_to_dev(kobj); |
367 | struct gpiod_data *data = dev_get_drvdata(dev); |
368 | struct gpio_desc *desc = data->desc; |
369 | umode_t mode = attr->mode; |
370 | bool show_direction = data->direction_can_change; |
371 | |
372 | if (attr == &dev_attr_direction.attr) { |
373 | if (!show_direction) |
374 | mode = 0; |
375 | } else if (attr == &dev_attr_edge.attr) { |
376 | if (gpiod_to_irq(desc) < 0) |
377 | mode = 0; |
378 | if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags)) |
379 | mode = 0; |
380 | } |
381 | |
382 | return mode; |
383 | } |
384 | |
385 | static struct attribute *gpio_attrs[] = { |
386 | &dev_attr_direction.attr, |
387 | &dev_attr_edge.attr, |
388 | &dev_attr_value.attr, |
389 | &dev_attr_active_low.attr, |
390 | NULL, |
391 | }; |
392 | |
393 | static const struct attribute_group gpio_group = { |
394 | .attrs = gpio_attrs, |
395 | .is_visible = gpio_is_visible, |
396 | }; |
397 | |
398 | static const struct attribute_group *gpio_groups[] = { |
399 | &gpio_group, |
400 | NULL |
401 | }; |
402 | |
403 | /* |
404 | * /sys/class/gpio/gpiochipN/ |
405 | * /base ... matching gpio_chip.base (N) |
406 | * /label ... matching gpio_chip.label |
407 | * /ngpio ... matching gpio_chip.ngpio |
408 | */ |
409 | |
410 | static ssize_t base_show(struct device *dev, |
411 | struct device_attribute *attr, char *buf) |
412 | { |
413 | const struct gpio_device *gdev = dev_get_drvdata(dev); |
414 | |
415 | return sysfs_emit(buf, fmt: "%d\n" , gdev->base); |
416 | } |
417 | static DEVICE_ATTR_RO(base); |
418 | |
419 | static ssize_t label_show(struct device *dev, |
420 | struct device_attribute *attr, char *buf) |
421 | { |
422 | const struct gpio_device *gdev = dev_get_drvdata(dev); |
423 | |
424 | return sysfs_emit(buf, fmt: "%s\n" , gdev->label); |
425 | } |
426 | static DEVICE_ATTR_RO(label); |
427 | |
428 | static ssize_t ngpio_show(struct device *dev, |
429 | struct device_attribute *attr, char *buf) |
430 | { |
431 | const struct gpio_device *gdev = dev_get_drvdata(dev); |
432 | |
433 | return sysfs_emit(buf, fmt: "%u\n" , gdev->ngpio); |
434 | } |
435 | static DEVICE_ATTR_RO(ngpio); |
436 | |
437 | static struct attribute *gpiochip_attrs[] = { |
438 | &dev_attr_base.attr, |
439 | &dev_attr_label.attr, |
440 | &dev_attr_ngpio.attr, |
441 | NULL, |
442 | }; |
443 | ATTRIBUTE_GROUPS(gpiochip); |
444 | |
445 | /* |
446 | * /sys/class/gpio/export ... write-only |
447 | * integer N ... number of GPIO to export (full access) |
448 | * /sys/class/gpio/unexport ... write-only |
449 | * integer N ... number of GPIO to unexport |
450 | */ |
451 | static ssize_t export_store(const struct class *class, |
452 | const struct class_attribute *attr, |
453 | const char *buf, size_t len) |
454 | { |
455 | struct gpio_desc *desc; |
456 | int status, offset; |
457 | long gpio; |
458 | |
459 | status = kstrtol(s: buf, base: 0, res: &gpio); |
460 | if (status) |
461 | return status; |
462 | |
463 | desc = gpio_to_desc(gpio); |
464 | /* reject invalid GPIOs */ |
465 | if (!desc) { |
466 | pr_warn("%s: invalid GPIO %ld\n" , __func__, gpio); |
467 | return -EINVAL; |
468 | } |
469 | |
470 | CLASS(gpio_chip_guard, guard)(desc); |
471 | if (!guard.gc) |
472 | return -ENODEV; |
473 | |
474 | offset = gpio_chip_hwgpio(desc); |
475 | if (!gpiochip_line_is_valid(gc: guard.gc, offset)) { |
476 | pr_warn("%s: GPIO %ld masked\n" , __func__, gpio); |
477 | return -EINVAL; |
478 | } |
479 | |
480 | /* No extra locking here; FLAG_SYSFS just signifies that the |
481 | * request and export were done by on behalf of userspace, so |
482 | * they may be undone on its behalf too. |
483 | */ |
484 | |
485 | status = gpiod_request_user(desc, label: "sysfs" ); |
486 | if (status) |
487 | goto done; |
488 | |
489 | status = gpiod_set_transitory(desc, transitory: false); |
490 | if (status) { |
491 | gpiod_free(desc); |
492 | goto done; |
493 | } |
494 | |
495 | status = gpiod_export(desc, direction_may_change: true); |
496 | if (status < 0) |
497 | gpiod_free(desc); |
498 | else |
499 | set_bit(FLAG_SYSFS, addr: &desc->flags); |
500 | |
501 | done: |
502 | if (status) |
503 | pr_debug("%s: status %d\n" , __func__, status); |
504 | return status ? : len; |
505 | } |
506 | static CLASS_ATTR_WO(export); |
507 | |
508 | static ssize_t unexport_store(const struct class *class, |
509 | const struct class_attribute *attr, |
510 | const char *buf, size_t len) |
511 | { |
512 | struct gpio_desc *desc; |
513 | int status; |
514 | long gpio; |
515 | |
516 | status = kstrtol(s: buf, base: 0, res: &gpio); |
517 | if (status < 0) |
518 | goto done; |
519 | |
520 | desc = gpio_to_desc(gpio); |
521 | /* reject bogus commands (gpiod_unexport() ignores them) */ |
522 | if (!desc) { |
523 | pr_warn("%s: invalid GPIO %ld\n" , __func__, gpio); |
524 | return -EINVAL; |
525 | } |
526 | |
527 | status = -EINVAL; |
528 | |
529 | /* No extra locking here; FLAG_SYSFS just signifies that the |
530 | * request and export were done by on behalf of userspace, so |
531 | * they may be undone on its behalf too. |
532 | */ |
533 | if (test_and_clear_bit(FLAG_SYSFS, addr: &desc->flags)) { |
534 | gpiod_unexport(desc); |
535 | gpiod_free(desc); |
536 | status = 0; |
537 | } |
538 | done: |
539 | if (status) |
540 | pr_debug("%s: status %d\n" , __func__, status); |
541 | return status ? : len; |
542 | } |
543 | static CLASS_ATTR_WO(unexport); |
544 | |
545 | static struct attribute *gpio_class_attrs[] = { |
546 | &class_attr_export.attr, |
547 | &class_attr_unexport.attr, |
548 | NULL, |
549 | }; |
550 | ATTRIBUTE_GROUPS(gpio_class); |
551 | |
552 | static struct class gpio_class = { |
553 | .name = "gpio" , |
554 | .class_groups = gpio_class_groups, |
555 | }; |
556 | |
557 | |
558 | /** |
559 | * gpiod_export - export a GPIO through sysfs |
560 | * @desc: GPIO to make available, already requested |
561 | * @direction_may_change: true if userspace may change GPIO direction |
562 | * Context: arch_initcall or later |
563 | * |
564 | * When drivers want to make a GPIO accessible to userspace after they |
565 | * have requested it -- perhaps while debugging, or as part of their |
566 | * public interface -- they may use this routine. If the GPIO can |
567 | * change direction (some can't) and the caller allows it, userspace |
568 | * will see "direction" sysfs attribute which may be used to change |
569 | * the gpio's direction. A "value" attribute will always be provided. |
570 | * |
571 | * Returns zero on success, else an error. |
572 | */ |
573 | int gpiod_export(struct gpio_desc *desc, bool direction_may_change) |
574 | { |
575 | const char *ioname = NULL; |
576 | struct gpio_device *gdev; |
577 | struct gpiod_data *data; |
578 | struct device *dev; |
579 | int status, offset; |
580 | |
581 | /* can't export until sysfs is available ... */ |
582 | if (!class_is_registered(class: &gpio_class)) { |
583 | pr_debug("%s: called too early!\n" , __func__); |
584 | return -ENOENT; |
585 | } |
586 | |
587 | if (!desc) { |
588 | pr_debug("%s: invalid gpio descriptor\n" , __func__); |
589 | return -EINVAL; |
590 | } |
591 | |
592 | CLASS(gpio_chip_guard, guard)(desc); |
593 | if (!guard.gc) |
594 | return -ENODEV; |
595 | |
596 | if (test_and_set_bit(FLAG_EXPORT, addr: &desc->flags)) |
597 | return -EPERM; |
598 | |
599 | gdev = desc->gdev; |
600 | |
601 | mutex_lock(&sysfs_lock); |
602 | |
603 | /* check if chip is being removed */ |
604 | if (!gdev->mockdev) { |
605 | status = -ENODEV; |
606 | goto err_unlock; |
607 | } |
608 | |
609 | if (!test_bit(FLAG_REQUESTED, &desc->flags)) { |
610 | gpiod_dbg(desc, "%s: unavailable (not requested)\n" , __func__); |
611 | status = -EPERM; |
612 | goto err_unlock; |
613 | } |
614 | |
615 | data = kzalloc(size: sizeof(*data), GFP_KERNEL); |
616 | if (!data) { |
617 | status = -ENOMEM; |
618 | goto err_unlock; |
619 | } |
620 | |
621 | data->desc = desc; |
622 | mutex_init(&data->mutex); |
623 | if (guard.gc->direction_input && guard.gc->direction_output) |
624 | data->direction_can_change = direction_may_change; |
625 | else |
626 | data->direction_can_change = false; |
627 | |
628 | offset = gpio_chip_hwgpio(desc); |
629 | if (guard.gc->names && guard.gc->names[offset]) |
630 | ioname = guard.gc->names[offset]; |
631 | |
632 | dev = device_create_with_groups(cls: &gpio_class, parent: &gdev->dev, |
633 | MKDEV(0, 0), drvdata: data, groups: gpio_groups, |
634 | fmt: ioname ? ioname : "gpio%u" , |
635 | desc_to_gpio(desc)); |
636 | if (IS_ERR(ptr: dev)) { |
637 | status = PTR_ERR(ptr: dev); |
638 | goto err_free_data; |
639 | } |
640 | |
641 | mutex_unlock(lock: &sysfs_lock); |
642 | return 0; |
643 | |
644 | err_free_data: |
645 | kfree(objp: data); |
646 | err_unlock: |
647 | mutex_unlock(lock: &sysfs_lock); |
648 | clear_bit(FLAG_EXPORT, addr: &desc->flags); |
649 | gpiod_dbg(desc, "%s: status %d\n" , __func__, status); |
650 | return status; |
651 | } |
652 | EXPORT_SYMBOL_GPL(gpiod_export); |
653 | |
654 | static int match_export(struct device *dev, const void *desc) |
655 | { |
656 | struct gpiod_data *data = dev_get_drvdata(dev); |
657 | |
658 | return data->desc == desc; |
659 | } |
660 | |
661 | /** |
662 | * gpiod_export_link - create a sysfs link to an exported GPIO node |
663 | * @dev: device under which to create symlink |
664 | * @name: name of the symlink |
665 | * @desc: GPIO to create symlink to, already exported |
666 | * |
667 | * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN |
668 | * node. Caller is responsible for unlinking. |
669 | * |
670 | * Returns zero on success, else an error. |
671 | */ |
672 | int gpiod_export_link(struct device *dev, const char *name, |
673 | struct gpio_desc *desc) |
674 | { |
675 | struct device *cdev; |
676 | int ret; |
677 | |
678 | if (!desc) { |
679 | pr_warn("%s: invalid GPIO\n" , __func__); |
680 | return -EINVAL; |
681 | } |
682 | |
683 | cdev = class_find_device(class: &gpio_class, NULL, data: desc, match: match_export); |
684 | if (!cdev) |
685 | return -ENODEV; |
686 | |
687 | ret = sysfs_create_link(kobj: &dev->kobj, target: &cdev->kobj, name); |
688 | put_device(dev: cdev); |
689 | |
690 | return ret; |
691 | } |
692 | EXPORT_SYMBOL_GPL(gpiod_export_link); |
693 | |
694 | /** |
695 | * gpiod_unexport - reverse effect of gpiod_export() |
696 | * @desc: GPIO to make unavailable |
697 | * |
698 | * This is implicit on gpiod_free(). |
699 | */ |
700 | void gpiod_unexport(struct gpio_desc *desc) |
701 | { |
702 | struct gpiod_data *data; |
703 | struct device *dev; |
704 | |
705 | if (!desc) { |
706 | pr_warn("%s: invalid GPIO\n" , __func__); |
707 | return; |
708 | } |
709 | |
710 | mutex_lock(&sysfs_lock); |
711 | |
712 | if (!test_bit(FLAG_EXPORT, &desc->flags)) |
713 | goto err_unlock; |
714 | |
715 | dev = class_find_device(class: &gpio_class, NULL, data: desc, match: match_export); |
716 | if (!dev) |
717 | goto err_unlock; |
718 | |
719 | data = dev_get_drvdata(dev); |
720 | |
721 | clear_bit(FLAG_EXPORT, addr: &desc->flags); |
722 | |
723 | device_unregister(dev); |
724 | |
725 | /* |
726 | * Release irq after deregistration to prevent race with edge_store. |
727 | */ |
728 | if (data->irq_flags) |
729 | gpio_sysfs_free_irq(dev); |
730 | |
731 | mutex_unlock(lock: &sysfs_lock); |
732 | |
733 | put_device(dev); |
734 | kfree(objp: data); |
735 | |
736 | return; |
737 | |
738 | err_unlock: |
739 | mutex_unlock(lock: &sysfs_lock); |
740 | } |
741 | EXPORT_SYMBOL_GPL(gpiod_unexport); |
742 | |
743 | int gpiochip_sysfs_register(struct gpio_device *gdev) |
744 | { |
745 | struct gpio_chip *chip; |
746 | struct device *parent; |
747 | struct device *dev; |
748 | |
749 | /* |
750 | * Many systems add gpio chips for SOC support very early, |
751 | * before driver model support is available. In those cases we |
752 | * register later, in gpiolib_sysfs_init() ... here we just |
753 | * verify that _some_ field of gpio_class got initialized. |
754 | */ |
755 | if (!class_is_registered(class: &gpio_class)) |
756 | return 0; |
757 | |
758 | guard(srcu)(l: &gdev->srcu); |
759 | |
760 | chip = srcu_dereference(gdev->chip, &gdev->srcu); |
761 | if (!chip) |
762 | return -ENODEV; |
763 | |
764 | /* |
765 | * For sysfs backward compatibility we need to preserve this |
766 | * preferred parenting to the gpio_chip parent field, if set. |
767 | */ |
768 | if (chip->parent) |
769 | parent = chip->parent; |
770 | else |
771 | parent = &gdev->dev; |
772 | |
773 | /* use chip->base for the ID; it's already known to be unique */ |
774 | dev = device_create_with_groups(cls: &gpio_class, parent, MKDEV(0, 0), drvdata: gdev, |
775 | groups: gpiochip_groups, GPIOCHIP_NAME "%d" , |
776 | chip->base); |
777 | if (IS_ERR(ptr: dev)) |
778 | return PTR_ERR(ptr: dev); |
779 | |
780 | mutex_lock(&sysfs_lock); |
781 | gdev->mockdev = dev; |
782 | mutex_unlock(lock: &sysfs_lock); |
783 | |
784 | return 0; |
785 | } |
786 | |
787 | void gpiochip_sysfs_unregister(struct gpio_device *gdev) |
788 | { |
789 | struct gpio_desc *desc; |
790 | struct gpio_chip *chip; |
791 | |
792 | scoped_guard(mutex, &sysfs_lock) { |
793 | if (!gdev->mockdev) |
794 | return; |
795 | |
796 | device_unregister(dev: gdev->mockdev); |
797 | |
798 | /* prevent further gpiod exports */ |
799 | gdev->mockdev = NULL; |
800 | } |
801 | |
802 | guard(srcu)(l: &gdev->srcu); |
803 | |
804 | chip = srcu_dereference(gdev->chip, &gdev->srcu); |
805 | if (!chip) |
806 | return; |
807 | |
808 | /* unregister gpiod class devices owned by sysfs */ |
809 | for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) { |
810 | gpiod_unexport(desc); |
811 | gpiod_free(desc); |
812 | } |
813 | } |
814 | |
815 | /* |
816 | * We're not really looking for a device - we just want to iterate over the |
817 | * list and call this callback for each GPIO device. This is why this function |
818 | * always returns 0. |
819 | */ |
820 | static int gpiofind_sysfs_register(struct gpio_chip *gc, const void *data) |
821 | { |
822 | struct gpio_device *gdev = gc->gpiodev; |
823 | int ret; |
824 | |
825 | if (gdev->mockdev) |
826 | return 0; |
827 | |
828 | ret = gpiochip_sysfs_register(gdev); |
829 | if (ret) |
830 | chip_err(gc, "failed to register the sysfs entry: %d\n" , ret); |
831 | |
832 | return 0; |
833 | } |
834 | |
835 | static int __init gpiolib_sysfs_init(void) |
836 | { |
837 | int status; |
838 | |
839 | status = class_register(class: &gpio_class); |
840 | if (status < 0) |
841 | return status; |
842 | |
843 | /* Scan and register the gpio_chips which registered very |
844 | * early (e.g. before the class_register above was called). |
845 | * |
846 | * We run before arch_initcall() so chip->dev nodes can have |
847 | * registered, and so arch_initcall() can always gpiod_export(). |
848 | */ |
849 | (void)gpio_device_find(NULL, match: gpiofind_sysfs_register); |
850 | |
851 | return 0; |
852 | } |
853 | postcore_initcall(gpiolib_sysfs_init); |
854 | |