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 | |
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(lock: &data->mutex); |
84 | |
85 | return sysfs_emit(buf, fmt: "%s\n" , value ? "out" : "in" ); |
86 | } |
87 | |
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(s1: buf, s2: "high" )) |
98 | status = gpiod_direction_output_raw(desc, value: 1); |
99 | else if (sysfs_streq(s1: buf, s2: "out" ) || sysfs_streq(s1: buf, s2: "low" )) |
100 | status = gpiod_direction_output_raw(desc, value: 0); |
101 | else if (sysfs_streq(s1: buf, s2: "in" )) |
102 | status = gpiod_direction_input(desc); |
103 | else |
104 | status = -EINVAL; |
105 | |
106 | mutex_unlock(lock: &data->mutex); |
107 | |
108 | return status ? : size; |
109 | } |
110 | static DEVICE_ATTR_RW(direction); |
111 | |
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(lock: &data->mutex); |
124 | |
125 | if (status < 0) |
126 | return status; |
127 | |
128 | return sysfs_emit(buf, fmt: "%zd\n" , status); |
129 | } |
130 | |
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(s: buf, base: 0, res: &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(lock: &data->mutex); |
151 | |
152 | return status; |
153 | } |
154 | static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store); |
155 | |
156 | static irqreturn_t gpio_sysfs_irq(int irq, void *priv) |
157 | { |
158 | struct gpiod_data *data = priv; |
159 | |
160 | sysfs_notify_dirent(kn: data->value_kn); |
161 | |
162 | return IRQ_HANDLED; |
163 | } |
164 | |
165 | /* Caller holds gpiod-data mutex. */ |
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(parent: dev->kobj.sd, name: "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(gc: desc->gdev->chip, offset: gpio_chip_hwgpio(desc)); |
198 | if (ret < 0) |
199 | goto err_put_kn; |
200 | |
201 | ret = request_any_context_irq(irq: data->irq, handler: gpio_sysfs_irq, flags: irq_flags, |
202 | name: "gpiolib" , dev_id: 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(gc: desc->gdev->chip, offset: gpio_chip_hwgpio(desc)); |
212 | err_put_kn: |
213 | sysfs_put(kn: data->value_kn); |
214 | |
215 | return ret; |
216 | } |
217 | |
218 | /* |
219 | * Caller holds gpiod-data mutex (unless called after class-device |
220 | * deregistration). |
221 | */ |
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(gc: desc->gdev->chip, offset: gpio_chip_hwgpio(desc)); |
230 | sysfs_put(kn: 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 | |
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(lock: &data->mutex); |
251 | |
252 | if (flags >= ARRAY_SIZE(trigger_names)) |
253 | return 0; |
254 | |
255 | return sysfs_emit(buf, fmt: "%s\n" , trigger_names[flags]); |
256 | } |
257 | |
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(lock: &data->mutex); |
287 | |
288 | return status; |
289 | } |
290 | static DEVICE_ATTR_RW(edge); |
291 | |
292 | /* Caller holds gpiod-data mutex. */ |
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, addr: &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 | |
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(lock: &data->mutex); |
327 | |
328 | return sysfs_emit(buf, fmt: "%d\n" , value); |
329 | } |
330 | |
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(s: buf, base: 0, res: &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(lock: &data->mutex); |
347 | |
348 | return status ? : size; |
349 | } |
350 | static DEVICE_ATTR_RW(active_low); |
351 | |
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 | |
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, fmt: "%d\n" , chip->base); |
405 | } |
406 | static DEVICE_ATTR_RO(base); |
407 | |
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, fmt: "%s\n" , chip->label ?: "" ); |
414 | } |
415 | static DEVICE_ATTR_RO(label); |
416 | |
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, fmt: "%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 | */ |
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(s: buf, base: 0, res: &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, label: "sysfs" ); |
473 | if (status) |
474 | goto done; |
475 | |
476 | status = gpiod_set_transitory(desc, transitory: false); |
477 | if (!status) { |
478 | status = gpiod_export(desc, direction_may_change: true); |
479 | if (status < 0) |
480 | gpiod_free(desc); |
481 | else |
482 | set_bit(FLAG_SYSFS, addr: &desc->flags); |
483 | } |
484 | |
485 | done: |
486 | if (status) |
487 | pr_debug("%s: status %d\n" , __func__, status); |
488 | return status ? : len; |
489 | } |
490 | static CLASS_ATTR_WO(export); |
491 | |
492 | static ssize_t unexport_store(const struct class *class, |
493 | const struct class_attribute *attr, |
494 | const char *buf, size_t len) |
495 | { |
496 | long gpio; |
497 | struct gpio_desc *desc; |
498 | int status; |
499 | |
500 | status = kstrtol(s: buf, base: 0, res: &gpio); |
501 | if (status < 0) |
502 | goto done; |
503 | |
504 | desc = gpio_to_desc(gpio); |
505 | /* reject bogus commands (gpiod_unexport() ignores them) */ |
506 | if (!desc) { |
507 | pr_warn("%s: invalid GPIO %ld\n" , __func__, gpio); |
508 | return -EINVAL; |
509 | } |
510 | |
511 | status = -EINVAL; |
512 | |
513 | /* No extra locking here; FLAG_SYSFS just signifies that the |
514 | * request and export were done by on behalf of userspace, so |
515 | * they may be undone on its behalf too. |
516 | */ |
517 | if (test_and_clear_bit(FLAG_SYSFS, addr: &desc->flags)) { |
518 | gpiod_unexport(desc); |
519 | gpiod_free(desc); |
520 | status = 0; |
521 | } |
522 | done: |
523 | if (status) |
524 | pr_debug("%s: status %d\n" , __func__, status); |
525 | return status ? : len; |
526 | } |
527 | static CLASS_ATTR_WO(unexport); |
528 | |
529 | static struct attribute *gpio_class_attrs[] = { |
530 | &class_attr_export.attr, |
531 | &class_attr_unexport.attr, |
532 | NULL, |
533 | }; |
534 | ATTRIBUTE_GROUPS(gpio_class); |
535 | |
536 | static struct class gpio_class = { |
537 | .name = "gpio" , |
538 | .class_groups = gpio_class_groups, |
539 | }; |
540 | |
541 | |
542 | /** |
543 | * gpiod_export - export a GPIO through sysfs |
544 | * @desc: GPIO to make available, already requested |
545 | * @direction_may_change: true if userspace may change GPIO direction |
546 | * Context: arch_initcall or later |
547 | * |
548 | * When drivers want to make a GPIO accessible to userspace after they |
549 | * have requested it -- perhaps while debugging, or as part of their |
550 | * public interface -- they may use this routine. If the GPIO can |
551 | * change direction (some can't) and the caller allows it, userspace |
552 | * will see "direction" sysfs attribute which may be used to change |
553 | * the gpio's direction. A "value" attribute will always be provided. |
554 | * |
555 | * Returns zero on success, else an error. |
556 | */ |
557 | int gpiod_export(struct gpio_desc *desc, bool direction_may_change) |
558 | { |
559 | struct gpio_chip *chip; |
560 | struct gpio_device *gdev; |
561 | struct gpiod_data *data; |
562 | unsigned long flags; |
563 | int status; |
564 | const char *ioname = NULL; |
565 | struct device *dev; |
566 | int offset; |
567 | |
568 | /* can't export until sysfs is available ... */ |
569 | if (!class_is_registered(class: &gpio_class)) { |
570 | pr_debug("%s: called too early!\n" , __func__); |
571 | return -ENOENT; |
572 | } |
573 | |
574 | if (!desc) { |
575 | pr_debug("%s: invalid gpio descriptor\n" , __func__); |
576 | return -EINVAL; |
577 | } |
578 | |
579 | gdev = desc->gdev; |
580 | chip = gdev->chip; |
581 | |
582 | mutex_lock(&sysfs_lock); |
583 | |
584 | /* check if chip is being removed */ |
585 | if (!chip || !gdev->mockdev) { |
586 | status = -ENODEV; |
587 | goto err_unlock; |
588 | } |
589 | |
590 | spin_lock_irqsave(&gpio_lock, flags); |
591 | if (!test_bit(FLAG_REQUESTED, &desc->flags) || |
592 | test_bit(FLAG_EXPORT, &desc->flags)) { |
593 | spin_unlock_irqrestore(lock: &gpio_lock, flags); |
594 | gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n" , |
595 | __func__, |
596 | test_bit(FLAG_REQUESTED, &desc->flags), |
597 | test_bit(FLAG_EXPORT, &desc->flags)); |
598 | status = -EPERM; |
599 | goto err_unlock; |
600 | } |
601 | spin_unlock_irqrestore(lock: &gpio_lock, flags); |
602 | |
603 | data = kzalloc(size: sizeof(*data), GFP_KERNEL); |
604 | if (!data) { |
605 | status = -ENOMEM; |
606 | goto err_unlock; |
607 | } |
608 | |
609 | data->desc = desc; |
610 | mutex_init(&data->mutex); |
611 | if (chip->direction_input && chip->direction_output) |
612 | data->direction_can_change = direction_may_change; |
613 | else |
614 | data->direction_can_change = false; |
615 | |
616 | offset = gpio_chip_hwgpio(desc); |
617 | if (chip->names && chip->names[offset]) |
618 | ioname = chip->names[offset]; |
619 | |
620 | dev = device_create_with_groups(cls: &gpio_class, parent: &gdev->dev, |
621 | MKDEV(0, 0), drvdata: data, groups: gpio_groups, |
622 | fmt: ioname ? ioname : "gpio%u" , |
623 | desc_to_gpio(desc)); |
624 | if (IS_ERR(ptr: dev)) { |
625 | status = PTR_ERR(ptr: dev); |
626 | goto err_free_data; |
627 | } |
628 | |
629 | set_bit(FLAG_EXPORT, addr: &desc->flags); |
630 | mutex_unlock(lock: &sysfs_lock); |
631 | return 0; |
632 | |
633 | err_free_data: |
634 | kfree(objp: data); |
635 | err_unlock: |
636 | mutex_unlock(lock: &sysfs_lock); |
637 | gpiod_dbg(desc, "%s: status %d\n" , __func__, status); |
638 | return status; |
639 | } |
640 | EXPORT_SYMBOL_GPL(gpiod_export); |
641 | |
642 | static int match_export(struct device *dev, const void *desc) |
643 | { |
644 | struct gpiod_data *data = dev_get_drvdata(dev); |
645 | |
646 | return data->desc == desc; |
647 | } |
648 | |
649 | /** |
650 | * gpiod_export_link - create a sysfs link to an exported GPIO node |
651 | * @dev: device under which to create symlink |
652 | * @name: name of the symlink |
653 | * @desc: GPIO to create symlink to, already exported |
654 | * |
655 | * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN |
656 | * node. Caller is responsible for unlinking. |
657 | * |
658 | * Returns zero on success, else an error. |
659 | */ |
660 | int gpiod_export_link(struct device *dev, const char *name, |
661 | struct gpio_desc *desc) |
662 | { |
663 | struct device *cdev; |
664 | int ret; |
665 | |
666 | if (!desc) { |
667 | pr_warn("%s: invalid GPIO\n" , __func__); |
668 | return -EINVAL; |
669 | } |
670 | |
671 | cdev = class_find_device(class: &gpio_class, NULL, data: desc, match: match_export); |
672 | if (!cdev) |
673 | return -ENODEV; |
674 | |
675 | ret = sysfs_create_link(kobj: &dev->kobj, target: &cdev->kobj, name); |
676 | put_device(dev: cdev); |
677 | |
678 | return ret; |
679 | } |
680 | EXPORT_SYMBOL_GPL(gpiod_export_link); |
681 | |
682 | /** |
683 | * gpiod_unexport - reverse effect of gpiod_export() |
684 | * @desc: GPIO to make unavailable |
685 | * |
686 | * This is implicit on gpiod_free(). |
687 | */ |
688 | void gpiod_unexport(struct gpio_desc *desc) |
689 | { |
690 | struct gpiod_data *data; |
691 | struct device *dev; |
692 | |
693 | if (!desc) { |
694 | pr_warn("%s: invalid GPIO\n" , __func__); |
695 | return; |
696 | } |
697 | |
698 | mutex_lock(&sysfs_lock); |
699 | |
700 | if (!test_bit(FLAG_EXPORT, &desc->flags)) |
701 | goto err_unlock; |
702 | |
703 | dev = class_find_device(class: &gpio_class, NULL, data: desc, match: match_export); |
704 | if (!dev) |
705 | goto err_unlock; |
706 | |
707 | data = dev_get_drvdata(dev); |
708 | |
709 | clear_bit(FLAG_EXPORT, addr: &desc->flags); |
710 | |
711 | device_unregister(dev); |
712 | |
713 | /* |
714 | * Release irq after deregistration to prevent race with edge_store. |
715 | */ |
716 | if (data->irq_flags) |
717 | gpio_sysfs_free_irq(dev); |
718 | |
719 | mutex_unlock(lock: &sysfs_lock); |
720 | |
721 | put_device(dev); |
722 | kfree(objp: data); |
723 | |
724 | return; |
725 | |
726 | err_unlock: |
727 | mutex_unlock(lock: &sysfs_lock); |
728 | } |
729 | EXPORT_SYMBOL_GPL(gpiod_unexport); |
730 | |
731 | int gpiochip_sysfs_register(struct gpio_device *gdev) |
732 | { |
733 | struct device *dev; |
734 | struct device *parent; |
735 | struct gpio_chip *chip = gdev->chip; |
736 | |
737 | /* |
738 | * Many systems add gpio chips for SOC support very early, |
739 | * before driver model support is available. In those cases we |
740 | * register later, in gpiolib_sysfs_init() ... here we just |
741 | * verify that _some_ field of gpio_class got initialized. |
742 | */ |
743 | if (!class_is_registered(class: &gpio_class)) |
744 | return 0; |
745 | |
746 | /* |
747 | * For sysfs backward compatibility we need to preserve this |
748 | * preferred parenting to the gpio_chip parent field, if set. |
749 | */ |
750 | if (chip->parent) |
751 | parent = chip->parent; |
752 | else |
753 | parent = &gdev->dev; |
754 | |
755 | /* use chip->base for the ID; it's already known to be unique */ |
756 | dev = device_create_with_groups(cls: &gpio_class, parent, MKDEV(0, 0), drvdata: chip, |
757 | groups: gpiochip_groups, GPIOCHIP_NAME "%d" , |
758 | chip->base); |
759 | if (IS_ERR(ptr: dev)) |
760 | return PTR_ERR(ptr: dev); |
761 | |
762 | mutex_lock(&sysfs_lock); |
763 | gdev->mockdev = dev; |
764 | mutex_unlock(lock: &sysfs_lock); |
765 | |
766 | return 0; |
767 | } |
768 | |
769 | void gpiochip_sysfs_unregister(struct gpio_device *gdev) |
770 | { |
771 | struct gpio_desc *desc; |
772 | struct gpio_chip *chip = gdev->chip; |
773 | |
774 | if (!gdev->mockdev) |
775 | return; |
776 | |
777 | device_unregister(dev: gdev->mockdev); |
778 | |
779 | /* prevent further gpiod exports */ |
780 | mutex_lock(&sysfs_lock); |
781 | gdev->mockdev = NULL; |
782 | mutex_unlock(lock: &sysfs_lock); |
783 | |
784 | /* unregister gpiod class devices owned by sysfs */ |
785 | for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) { |
786 | gpiod_unexport(desc); |
787 | gpiod_free(desc); |
788 | } |
789 | } |
790 | |
791 | static int __init gpiolib_sysfs_init(void) |
792 | { |
793 | int status; |
794 | unsigned long flags; |
795 | struct gpio_device *gdev; |
796 | |
797 | status = class_register(class: &gpio_class); |
798 | if (status < 0) |
799 | return status; |
800 | |
801 | /* Scan and register the gpio_chips which registered very |
802 | * early (e.g. before the class_register above was called). |
803 | * |
804 | * We run before arch_initcall() so chip->dev nodes can have |
805 | * registered, and so arch_initcall() can always gpiod_export(). |
806 | */ |
807 | spin_lock_irqsave(&gpio_lock, flags); |
808 | list_for_each_entry(gdev, &gpio_devices, list) { |
809 | if (gdev->mockdev) |
810 | continue; |
811 | |
812 | /* |
813 | * TODO we yield gpio_lock here because |
814 | * gpiochip_sysfs_register() acquires a mutex. This is unsafe |
815 | * and needs to be fixed. |
816 | * |
817 | * Also it would be nice to use gpio_device_find() here so we |
818 | * can keep gpio_chips local to gpiolib.c, but the yield of |
819 | * gpio_lock prevents us from doing this. |
820 | */ |
821 | spin_unlock_irqrestore(lock: &gpio_lock, flags); |
822 | status = gpiochip_sysfs_register(gdev); |
823 | spin_lock_irqsave(&gpio_lock, flags); |
824 | } |
825 | spin_unlock_irqrestore(lock: &gpio_lock, flags); |
826 | |
827 | return status; |
828 | } |
829 | postcore_initcall(gpiolib_sysfs_init); |
830 | |