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1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/anon_inodes.h>
4#include <linux/bitmap.h>
5#include <linux/cdev.h>
6#include <linux/compat.h>
7#include <linux/device.h>
8#include <linux/err.h>
9#include <linux/file.h>
10#include <linux/gpio.h>
11#include <linux/gpio/driver.h>
12#include <linux/interrupt.h>
13#include <linux/irqreturn.h>
14#include <linux/kernel.h>
15#include <linux/kfifo.h>
16#include <linux/module.h>
17#include <linux/pinctrl/consumer.h>
18#include <linux/poll.h>
19#include <linux/spinlock.h>
20#include <linux/timekeeping.h>
21#include <linux/uaccess.h>
22#include <uapi/linux/gpio.h>
23
24#include "gpiolib.h"
25#include "gpiolib-cdev.h"
26
27/* Character device interface to GPIO.
28 *
29 * The GPIO character device, /dev/gpiochipN, provides userspace an
30 * interface to gpiolib GPIOs via ioctl()s.
31 */
32
33/*
34 * GPIO line handle management
35 */
36
37/**
38 * struct linehandle_state - contains the state of a userspace handle
39 * @gdev: the GPIO device the handle pertains to
40 * @label: consumer label used to tag descriptors
41 * @descs: the GPIO descriptors held by this handle
42 * @num_descs: the number of descriptors held in the descs array
43 */
44struct linehandle_state {
45 struct gpio_device *gdev;
46 const char *label;
47 struct gpio_desc *descs[GPIOHANDLES_MAX];
48 u32 num_descs;
49};
50
51#define GPIOHANDLE_REQUEST_VALID_FLAGS \
52 (GPIOHANDLE_REQUEST_INPUT | \
53 GPIOHANDLE_REQUEST_OUTPUT | \
54 GPIOHANDLE_REQUEST_ACTIVE_LOW | \
55 GPIOHANDLE_REQUEST_BIAS_PULL_UP | \
56 GPIOHANDLE_REQUEST_BIAS_PULL_DOWN | \
57 GPIOHANDLE_REQUEST_BIAS_DISABLE | \
58 GPIOHANDLE_REQUEST_OPEN_DRAIN | \
59 GPIOHANDLE_REQUEST_OPEN_SOURCE)
60
61static int linehandle_validate_flags(u32 flags)
62{
63 /* Return an error if an unknown flag is set */
64 if (flags & ~GPIOHANDLE_REQUEST_VALID_FLAGS)
65 return -EINVAL;
66
67 /*
68 * Do not allow both INPUT & OUTPUT flags to be set as they are
69 * contradictory.
70 */
71 if ((flags & GPIOHANDLE_REQUEST_INPUT) &&
72 (flags & GPIOHANDLE_REQUEST_OUTPUT))
73 return -EINVAL;
74
75 /*
76 * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
77 * the hardware actually supports enabling both at the same time the
78 * electrical result would be disastrous.
79 */
80 if ((flags & GPIOHANDLE_REQUEST_OPEN_DRAIN) &&
81 (flags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
82 return -EINVAL;
83
84 /* OPEN_DRAIN and OPEN_SOURCE flags only make sense for output mode. */
85 if (!(flags & GPIOHANDLE_REQUEST_OUTPUT) &&
86 ((flags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
87 (flags & GPIOHANDLE_REQUEST_OPEN_SOURCE)))
88 return -EINVAL;
89
90 /* Bias flags only allowed for input or output mode. */
91 if (!((flags & GPIOHANDLE_REQUEST_INPUT) ||
92 (flags & GPIOHANDLE_REQUEST_OUTPUT)) &&
93 ((flags & GPIOHANDLE_REQUEST_BIAS_DISABLE) ||
94 (flags & GPIOHANDLE_REQUEST_BIAS_PULL_UP) ||
95 (flags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN)))
96 return -EINVAL;
97
98 /* Only one bias flag can be set. */
99 if (((flags & GPIOHANDLE_REQUEST_BIAS_DISABLE) &&
100 (flags & (GPIOHANDLE_REQUEST_BIAS_PULL_DOWN |
101 GPIOHANDLE_REQUEST_BIAS_PULL_UP))) ||
102 ((flags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN) &&
103 (flags & GPIOHANDLE_REQUEST_BIAS_PULL_UP)))
104 return -EINVAL;
105
106 return 0;
107}
108
109static void linehandle_flags_to_desc_flags(u32 lflags, unsigned long *flagsp)
110{
111 assign_bit(FLAG_ACTIVE_LOW, flagsp,
112 lflags & GPIOHANDLE_REQUEST_ACTIVE_LOW);
113 assign_bit(FLAG_OPEN_DRAIN, flagsp,
114 lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN);
115 assign_bit(FLAG_OPEN_SOURCE, flagsp,
116 lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE);
117 assign_bit(FLAG_PULL_UP, flagsp,
118 lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP);
119 assign_bit(FLAG_PULL_DOWN, flagsp,
120 lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN);
121 assign_bit(FLAG_BIAS_DISABLE, flagsp,
122 lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE);
123}
124
125static long linehandle_set_config(struct linehandle_state *lh,
126 void __user *ip)
127{
128 struct gpiohandle_config gcnf;
129 struct gpio_desc *desc;
130 int i, ret;
131 u32 lflags;
132
133 if (copy_from_user(&gcnf, ip, sizeof(gcnf)))
134 return -EFAULT;
135
136 lflags = gcnf.flags;
137 ret = linehandle_validate_flags(lflags);
138 if (ret)
139 return ret;
140
141 for (i = 0; i < lh->num_descs; i++) {
142 desc = lh->descs[i];
143 linehandle_flags_to_desc_flags(gcnf.flags, &desc->flags);
144
145 /*
146 * Lines have to be requested explicitly for input
147 * or output, else the line will be treated "as is".
148 */
149 if (lflags & GPIOHANDLE_REQUEST_OUTPUT) {
150 int val = !!gcnf.default_values[i];
151
152 ret = gpiod_direction_output(desc, val);
153 if (ret)
154 return ret;
155 } else if (lflags & GPIOHANDLE_REQUEST_INPUT) {
156 ret = gpiod_direction_input(desc);
157 if (ret)
158 return ret;
159 }
160
161 blocking_notifier_call_chain(&desc->gdev->notifier,
162 GPIOLINE_CHANGED_CONFIG, desc);
163 }
164 return 0;
165}
166
167static long linehandle_ioctl(struct file *file, unsigned int cmd,
168 unsigned long arg)
169{
170 struct linehandle_state *lh = file->private_data;
171 void __user *ip = (void __user *)arg;
172 struct gpiohandle_data ghd;
173 DECLARE_BITMAP(vals, GPIOHANDLES_MAX);
174 int i;
175
176 if (cmd == GPIOHANDLE_GET_LINE_VALUES_IOCTL) {
177 /* NOTE: It's ok to read values of output lines. */
178 int ret = gpiod_get_array_value_complex(false,
179 true,
180 lh->num_descs,
181 lh->descs,
182 NULL,
183 vals);
184 if (ret)
185 return ret;
186
187 memset(&ghd, 0, sizeof(ghd));
188 for (i = 0; i < lh->num_descs; i++)
189 ghd.values[i] = test_bit(i, vals);
190
191 if (copy_to_user(ip, &ghd, sizeof(ghd)))
192 return -EFAULT;
193
194 return 0;
195 } else if (cmd == GPIOHANDLE_SET_LINE_VALUES_IOCTL) {
196 /*
197 * All line descriptors were created at once with the same
198 * flags so just check if the first one is really output.
199 */
200 if (!test_bit(FLAG_IS_OUT, &lh->descs[0]->flags))
201 return -EPERM;
202
203 if (copy_from_user(&ghd, ip, sizeof(ghd)))
204 return -EFAULT;
205
206 /* Clamp all values to [0,1] */
207 for (i = 0; i < lh->num_descs; i++)
208 __assign_bit(i, vals, ghd.values[i]);
209
210 /* Reuse the array setting function */
211 return gpiod_set_array_value_complex(false,
212 true,
213 lh->num_descs,
214 lh->descs,
215 NULL,
216 vals);
217 } else if (cmd == GPIOHANDLE_SET_CONFIG_IOCTL) {
218 return linehandle_set_config(lh, ip);
219 }
220 return -EINVAL;
221}
222
223#ifdef CONFIG_COMPAT
224static long linehandle_ioctl_compat(struct file *file, unsigned int cmd,
225 unsigned long arg)
226{
227 return linehandle_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
228}
229#endif
230
231static void linehandle_free(struct linehandle_state *lh)
232{
233 int i;
234
235 for (i = 0; i < lh->num_descs; i++)
236 if (lh->descs[i])
237 gpiod_free(lh->descs[i]);
238 kfree(lh->label);
239 put_device(&lh->gdev->dev);
240 kfree(lh);
241}
242
243static int linehandle_release(struct inode *inode, struct file *file)
244{
245 linehandle_free(file->private_data);
246 return 0;
247}
248
249static const struct file_operations linehandle_fileops = {
250 .release = linehandle_release,
251 .owner = THIS_MODULE,
252 .llseek = noop_llseek,
253 .unlocked_ioctl = linehandle_ioctl,
254#ifdef CONFIG_COMPAT
255 .compat_ioctl = linehandle_ioctl_compat,
256#endif
257};
258
259static int linehandle_create(struct gpio_device *gdev, void __user *ip)
260{
261 struct gpiohandle_request handlereq;
262 struct linehandle_state *lh;
263 struct file *file;
264 int fd, i, ret;
265 u32 lflags;
266
267 if (copy_from_user(&handlereq, ip, sizeof(handlereq)))
268 return -EFAULT;
269 if ((handlereq.lines == 0) || (handlereq.lines > GPIOHANDLES_MAX))
270 return -EINVAL;
271
272 lflags = handlereq.flags;
273
274 ret = linehandle_validate_flags(lflags);
275 if (ret)
276 return ret;
277
278 lh = kzalloc(sizeof(*lh), GFP_KERNEL);
279 if (!lh)
280 return -ENOMEM;
281 lh->gdev = gdev;
282 get_device(&gdev->dev);
283
284 /* Make sure this is terminated */
285 handlereq.consumer_label[sizeof(handlereq.consumer_label)-1] = '\0';
286 if (strlen(handlereq.consumer_label)) {
287 lh->label = kstrdup(handlereq.consumer_label,
288 GFP_KERNEL);
289 if (!lh->label) {
290 ret = -ENOMEM;
291 goto out_free_lh;
292 }
293 }
294
295 lh->num_descs = handlereq.lines;
296
297 /* Request each GPIO */
298 for (i = 0; i < handlereq.lines; i++) {
299 u32 offset = handlereq.lineoffsets[i];
300 struct gpio_desc *desc = gpiochip_get_desc(gdev->chip, offset);
301
302 if (IS_ERR(desc)) {
303 ret = PTR_ERR(desc);
304 goto out_free_lh;
305 }
306
307 ret = gpiod_request(desc, lh->label);
308 if (ret)
309 goto out_free_lh;
310 lh->descs[i] = desc;
311 linehandle_flags_to_desc_flags(handlereq.flags, &desc->flags);
312
313 ret = gpiod_set_transitory(desc, false);
314 if (ret < 0)
315 goto out_free_lh;
316
317 /*
318 * Lines have to be requested explicitly for input
319 * or output, else the line will be treated "as is".
320 */
321 if (lflags & GPIOHANDLE_REQUEST_OUTPUT) {
322 int val = !!handlereq.default_values[i];
323
324 ret = gpiod_direction_output(desc, val);
325 if (ret)
326 goto out_free_lh;
327 } else if (lflags & GPIOHANDLE_REQUEST_INPUT) {
328 ret = gpiod_direction_input(desc);
329 if (ret)
330 goto out_free_lh;
331 }
332
333 blocking_notifier_call_chain(&desc->gdev->notifier,
334 GPIOLINE_CHANGED_REQUESTED, desc);
335
336 dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
337 offset);
338 }
339
340 fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
341 if (fd < 0) {
342 ret = fd;
343 goto out_free_lh;
344 }
345
346 file = anon_inode_getfile("gpio-linehandle",
347 &linehandle_fileops,
348 lh,
349 O_RDONLY | O_CLOEXEC);
350 if (IS_ERR(file)) {
351 ret = PTR_ERR(file);
352 goto out_put_unused_fd;
353 }
354
355 handlereq.fd = fd;
356 if (copy_to_user(ip, &handlereq, sizeof(handlereq))) {
357 /*
358 * fput() will trigger the release() callback, so do not go onto
359 * the regular error cleanup path here.
360 */
361 fput(file);
362 put_unused_fd(fd);
363 return -EFAULT;
364 }
365
366 fd_install(fd, file);
367
368 dev_dbg(&gdev->dev, "registered chardev handle for %d lines\n",
369 lh->num_descs);
370
371 return 0;
372
373out_put_unused_fd:
374 put_unused_fd(fd);
375out_free_lh:
376 linehandle_free(lh);
377 return ret;
378}
379
380/*
381 * GPIO line event management
382 */
383
384/**
385 * struct lineevent_state - contains the state of a userspace event
386 * @gdev: the GPIO device the event pertains to
387 * @label: consumer label used to tag descriptors
388 * @desc: the GPIO descriptor held by this event
389 * @eflags: the event flags this line was requested with
390 * @irq: the interrupt that trigger in response to events on this GPIO
391 * @wait: wait queue that handles blocking reads of events
392 * @events: KFIFO for the GPIO events
393 * @timestamp: cache for the timestamp storing it between hardirq
394 * and IRQ thread, used to bring the timestamp close to the actual
395 * event
396 */
397struct lineevent_state {
398 struct gpio_device *gdev;
399 const char *label;
400 struct gpio_desc *desc;
401 u32 eflags;
402 int irq;
403 wait_queue_head_t wait;
404 DECLARE_KFIFO(events, struct gpioevent_data, 16);
405 u64 timestamp;
406};
407
408#define GPIOEVENT_REQUEST_VALID_FLAGS \
409 (GPIOEVENT_REQUEST_RISING_EDGE | \
410 GPIOEVENT_REQUEST_FALLING_EDGE)
411
412static __poll_t lineevent_poll(struct file *file,
413 struct poll_table_struct *wait)
414{
415 struct lineevent_state *le = file->private_data;
416 __poll_t events = 0;
417
418 poll_wait(file, &le->wait, wait);
419
420 if (!kfifo_is_empty_spinlocked_noirqsave(&le->events, &le->wait.lock))
421 events = EPOLLIN | EPOLLRDNORM;
422
423 return events;
424}
425
426static ssize_t lineevent_get_size(void)
427{
428#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
429 /* i386 has no padding after 'id' */
430 if (in_ia32_syscall()) {
431 struct compat_gpioeevent_data {
432 compat_u64 timestamp;
433 u32 id;
434 };
435
436 return sizeof(struct compat_gpioeevent_data);
437 }
438#endif
439 return sizeof(struct gpioevent_data);
440}
441
442static ssize_t lineevent_read(struct file *file,
443 char __user *buf,
444 size_t count,
445 loff_t *f_ps)
446{
447 struct lineevent_state *le = file->private_data;
448 struct gpioevent_data ge;
449 ssize_t bytes_read = 0;
450 ssize_t ge_size;
451 int ret;
452
453 /*
454 * When compatible system call is being used the struct gpioevent_data,
455 * in case of at least ia32, has different size due to the alignment
456 * differences. Because we have first member 64 bits followed by one of
457 * 32 bits there is no gap between them. The only difference is the
458 * padding at the end of the data structure. Hence, we calculate the
459 * actual sizeof() and pass this as an argument to copy_to_user() to
460 * drop unneeded bytes from the output.
461 */
462 ge_size = lineevent_get_size();
463 if (count < ge_size)
464 return -EINVAL;
465
466 do {
467 spin_lock(&le->wait.lock);
468 if (kfifo_is_empty(&le->events)) {
469 if (bytes_read) {
470 spin_unlock(&le->wait.lock);
471 return bytes_read;
472 }
473
474 if (file->f_flags & O_NONBLOCK) {
475 spin_unlock(&le->wait.lock);
476 return -EAGAIN;
477 }
478
479 ret = wait_event_interruptible_locked(le->wait,
480 !kfifo_is_empty(&le->events));
481 if (ret) {
482 spin_unlock(&le->wait.lock);
483 return ret;
484 }
485 }
486
487 ret = kfifo_out(&le->events, &ge, 1);
488 spin_unlock(&le->wait.lock);
489 if (ret != 1) {
490 /*
491 * This should never happen - we were holding the lock
492 * from the moment we learned the fifo is no longer
493 * empty until now.
494 */
495 ret = -EIO;
496 break;
497 }
498
499 if (copy_to_user(buf + bytes_read, &ge, ge_size))
500 return -EFAULT;
501 bytes_read += ge_size;
502 } while (count >= bytes_read + ge_size);
503
504 return bytes_read;
505}
506
507static void lineevent_free(struct lineevent_state *le)
508{
509 if (le->irq)
510 free_irq(le->irq, le);
511 if (le->desc)
512 gpiod_free(le->desc);
513 kfree(le->label);
514 put_device(&le->gdev->dev);
515 kfree(le);
516}
517
518static int lineevent_release(struct inode *inode, struct file *file)
519{
520 lineevent_free(file->private_data);
521 return 0;
522}
523
524static long lineevent_ioctl(struct file *file, unsigned int cmd,
525 unsigned long arg)
526{
527 struct lineevent_state *le = file->private_data;
528 void __user *ip = (void __user *)arg;
529 struct gpiohandle_data ghd;
530
531 /*
532 * We can get the value for an event line but not set it,
533 * because it is input by definition.
534 */
535 if (cmd == GPIOHANDLE_GET_LINE_VALUES_IOCTL) {
536 int val;
537
538 memset(&ghd, 0, sizeof(ghd));
539
540 val = gpiod_get_value_cansleep(le->desc);
541 if (val < 0)
542 return val;
543 ghd.values[0] = val;
544
545 if (copy_to_user(ip, &ghd, sizeof(ghd)))
546 return -EFAULT;
547
548 return 0;
549 }
550 return -EINVAL;
551}
552
553#ifdef CONFIG_COMPAT
554static long lineevent_ioctl_compat(struct file *file, unsigned int cmd,
555 unsigned long arg)
556{
557 return lineevent_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
558}
559#endif
560
561static const struct file_operations lineevent_fileops = {
562 .release = lineevent_release,
563 .read = lineevent_read,
564 .poll = lineevent_poll,
565 .owner = THIS_MODULE,
566 .llseek = noop_llseek,
567 .unlocked_ioctl = lineevent_ioctl,
568#ifdef CONFIG_COMPAT
569 .compat_ioctl = lineevent_ioctl_compat,
570#endif
571};
572
573static irqreturn_t lineevent_irq_thread(int irq, void *p)
574{
575 struct lineevent_state *le = p;
576 struct gpioevent_data ge;
577 int ret;
578
579 /* Do not leak kernel stack to userspace */
580 memset(&ge, 0, sizeof(ge));
581
582 /*
583 * We may be running from a nested threaded interrupt in which case
584 * we didn't get the timestamp from lineevent_irq_handler().
585 */
586 if (!le->timestamp)
587 ge.timestamp = ktime_get_ns();
588 else
589 ge.timestamp = le->timestamp;
590
591 if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE
592 && le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
593 int level = gpiod_get_value_cansleep(le->desc);
594
595 if (level)
596 /* Emit low-to-high event */
597 ge.id = GPIOEVENT_EVENT_RISING_EDGE;
598 else
599 /* Emit high-to-low event */
600 ge.id = GPIOEVENT_EVENT_FALLING_EDGE;
601 } else if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE) {
602 /* Emit low-to-high event */
603 ge.id = GPIOEVENT_EVENT_RISING_EDGE;
604 } else if (le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
605 /* Emit high-to-low event */
606 ge.id = GPIOEVENT_EVENT_FALLING_EDGE;
607 } else {
608 return IRQ_NONE;
609 }
610
611 ret = kfifo_in_spinlocked_noirqsave(&le->events, &ge,
612 1, &le->wait.lock);
613 if (ret)
614 wake_up_poll(&le->wait, EPOLLIN);
615 else
616 pr_debug_ratelimited("event FIFO is full - event dropped\n");
617
618 return IRQ_HANDLED;
619}
620
621static irqreturn_t lineevent_irq_handler(int irq, void *p)
622{
623 struct lineevent_state *le = p;
624
625 /*
626 * Just store the timestamp in hardirq context so we get it as
627 * close in time as possible to the actual event.
628 */
629 le->timestamp = ktime_get_ns();
630
631 return IRQ_WAKE_THREAD;
632}
633
634static int lineevent_create(struct gpio_device *gdev, void __user *ip)
635{
636 struct gpioevent_request eventreq;
637 struct lineevent_state *le;
638 struct gpio_desc *desc;
639 struct file *file;
640 u32 offset;
641 u32 lflags;
642 u32 eflags;
643 int fd;
644 int ret;
645 int irq, irqflags = 0;
646
647 if (copy_from_user(&eventreq, ip, sizeof(eventreq)))
648 return -EFAULT;
649
650 offset = eventreq.lineoffset;
651 lflags = eventreq.handleflags;
652 eflags = eventreq.eventflags;
653
654 desc = gpiochip_get_desc(gdev->chip, offset);
655 if (IS_ERR(desc))
656 return PTR_ERR(desc);
657
658 /* Return an error if a unknown flag is set */
659 if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
660 (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS))
661 return -EINVAL;
662
663 /* This is just wrong: we don't look for events on output lines */
664 if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) ||
665 (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
666 (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
667 return -EINVAL;
668
669 /* Only one bias flag can be set. */
670 if (((lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE) &&
671 (lflags & (GPIOHANDLE_REQUEST_BIAS_PULL_DOWN |
672 GPIOHANDLE_REQUEST_BIAS_PULL_UP))) ||
673 ((lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN) &&
674 (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP)))
675 return -EINVAL;
676
677 le = kzalloc(sizeof(*le), GFP_KERNEL);
678 if (!le)
679 return -ENOMEM;
680 le->gdev = gdev;
681 get_device(&gdev->dev);
682
683 /* Make sure this is terminated */
684 eventreq.consumer_label[sizeof(eventreq.consumer_label)-1] = '\0';
685 if (strlen(eventreq.consumer_label)) {
686 le->label = kstrdup(eventreq.consumer_label,
687 GFP_KERNEL);
688 if (!le->label) {
689 ret = -ENOMEM;
690 goto out_free_le;
691 }
692 }
693
694 ret = gpiod_request(desc, le->label);
695 if (ret)
696 goto out_free_le;
697 le->desc = desc;
698 le->eflags = eflags;
699
700 linehandle_flags_to_desc_flags(lflags, &desc->flags);
701
702 ret = gpiod_direction_input(desc);
703 if (ret)
704 goto out_free_le;
705
706 blocking_notifier_call_chain(&desc->gdev->notifier,
707 GPIOLINE_CHANGED_REQUESTED, desc);
708
709 irq = gpiod_to_irq(desc);
710 if (irq <= 0) {
711 ret = -ENODEV;
712 goto out_free_le;
713 }
714 le->irq = irq;
715
716 if (eflags & GPIOEVENT_REQUEST_RISING_EDGE)
717 irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
718 IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
719 if (eflags & GPIOEVENT_REQUEST_FALLING_EDGE)
720 irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
721 IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
722 irqflags |= IRQF_ONESHOT;
723
724 INIT_KFIFO(le->events);
725 init_waitqueue_head(&le->wait);
726
727 /* Request a thread to read the events */
728 ret = request_threaded_irq(le->irq,
729 lineevent_irq_handler,
730 lineevent_irq_thread,
731 irqflags,
732 le->label,
733 le);
734 if (ret)
735 goto out_free_le;
736
737 fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
738 if (fd < 0) {
739 ret = fd;
740 goto out_free_le;
741 }
742
743 file = anon_inode_getfile("gpio-event",
744 &lineevent_fileops,
745 le,
746 O_RDONLY | O_CLOEXEC);
747 if (IS_ERR(file)) {
748 ret = PTR_ERR(file);
749 goto out_put_unused_fd;
750 }
751
752 eventreq.fd = fd;
753 if (copy_to_user(ip, &eventreq, sizeof(eventreq))) {
754 /*
755 * fput() will trigger the release() callback, so do not go onto
756 * the regular error cleanup path here.
757 */
758 fput(file);
759 put_unused_fd(fd);
760 return -EFAULT;
761 }
762
763 fd_install(fd, file);
764
765 return 0;
766
767out_put_unused_fd:
768 put_unused_fd(fd);
769out_free_le:
770 lineevent_free(le);
771 return ret;
772}
773
774static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
775 struct gpioline_info *info)
776{
777 struct gpio_chip *gc = desc->gdev->chip;
778 bool ok_for_pinctrl;
779 unsigned long flags;
780
781 /*
782 * This function takes a mutex so we must check this before taking
783 * the spinlock.
784 *
785 * FIXME: find a non-racy way to retrieve this information. Maybe a
786 * lock common to both frameworks?
787 */
788 ok_for_pinctrl =
789 pinctrl_gpio_can_use_line(gc->base + info->line_offset);
790
791 spin_lock_irqsave(&gpio_lock, flags);
792
793 if (desc->name) {
794 strncpy(info->name, desc->name, sizeof(info->name));
795 info->name[sizeof(info->name) - 1] = '\0';
796 } else {
797 info->name[0] = '\0';
798 }
799
800 if (desc->label) {
801 strncpy(info->consumer, desc->label, sizeof(info->consumer));
802 info->consumer[sizeof(info->consumer) - 1] = '\0';
803 } else {
804 info->consumer[0] = '\0';
805 }
806
807 /*
808 * Userspace only need to know that the kernel is using this GPIO so
809 * it can't use it.
810 */
811 info->flags = 0;
812 if (test_bit(FLAG_REQUESTED, &desc->flags) ||
813 test_bit(FLAG_IS_HOGGED, &desc->flags) ||
814 test_bit(FLAG_USED_AS_IRQ, &desc->flags) ||
815 test_bit(FLAG_EXPORT, &desc->flags) ||
816 test_bit(FLAG_SYSFS, &desc->flags) ||
817 !ok_for_pinctrl)
818 info->flags |= GPIOLINE_FLAG_KERNEL;
819 if (test_bit(FLAG_IS_OUT, &desc->flags))
820 info->flags |= GPIOLINE_FLAG_IS_OUT;
821 if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
822 info->flags |= GPIOLINE_FLAG_ACTIVE_LOW;
823 if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
824 info->flags |= (GPIOLINE_FLAG_OPEN_DRAIN |
825 GPIOLINE_FLAG_IS_OUT);
826 if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
827 info->flags |= (GPIOLINE_FLAG_OPEN_SOURCE |
828 GPIOLINE_FLAG_IS_OUT);
829 if (test_bit(FLAG_BIAS_DISABLE, &desc->flags))
830 info->flags |= GPIOLINE_FLAG_BIAS_DISABLE;
831 if (test_bit(FLAG_PULL_DOWN, &desc->flags))
832 info->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
833 if (test_bit(FLAG_PULL_UP, &desc->flags))
834 info->flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
835
836 spin_unlock_irqrestore(&gpio_lock, flags);
837}
838
839struct gpio_chardev_data {
840 struct gpio_device *gdev;
841 wait_queue_head_t wait;
842 DECLARE_KFIFO(events, struct gpioline_info_changed, 32);
843 struct notifier_block lineinfo_changed_nb;
844 unsigned long *watched_lines;
845};
846
847/*
848 * gpio_ioctl() - ioctl handler for the GPIO chardev
849 */
850static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
851{
852 struct gpio_chardev_data *cdev = file->private_data;
853 struct gpio_device *gdev = cdev->gdev;
854 struct gpio_chip *gc = gdev->chip;
855 void __user *ip = (void __user *)arg;
856 struct gpio_desc *desc;
857 __u32 offset;
858
859 /* We fail any subsequent ioctl():s when the chip is gone */
860 if (!gc)
861 return -ENODEV;
862
863 /* Fill in the struct and pass to userspace */
864 if (cmd == GPIO_GET_CHIPINFO_IOCTL) {
865 struct gpiochip_info chipinfo;
866
867 memset(&chipinfo, 0, sizeof(chipinfo));
868
869 strncpy(chipinfo.name, dev_name(&gdev->dev),
870 sizeof(chipinfo.name));
871 chipinfo.name[sizeof(chipinfo.name)-1] = '\0';
872 strncpy(chipinfo.label, gdev->label,
873 sizeof(chipinfo.label));
874 chipinfo.label[sizeof(chipinfo.label)-1] = '\0';
875 chipinfo.lines = gdev->ngpio;
876 if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
877 return -EFAULT;
878 return 0;
879 } else if (cmd == GPIO_GET_LINEINFO_IOCTL) {
880 struct gpioline_info lineinfo;
881
882 if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
883 return -EFAULT;
884
885 /* this doubles as a range check on line_offset */
886 desc = gpiochip_get_desc(gc, lineinfo.line_offset);
887 if (IS_ERR(desc))
888 return PTR_ERR(desc);
889
890 gpio_desc_to_lineinfo(desc, &lineinfo);
891
892 if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
893 return -EFAULT;
894 return 0;
895 } else if (cmd == GPIO_GET_LINEHANDLE_IOCTL) {
896 return linehandle_create(gdev, ip);
897 } else if (cmd == GPIO_GET_LINEEVENT_IOCTL) {
898 return lineevent_create(gdev, ip);
899 } else if (cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) {
900 struct gpioline_info lineinfo;
901
902 if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
903 return -EFAULT;
904
905 /* this doubles as a range check on line_offset */
906 desc = gpiochip_get_desc(gc, lineinfo.line_offset);
907 if (IS_ERR(desc))
908 return PTR_ERR(desc);
909
910 if (test_and_set_bit(lineinfo.line_offset, cdev->watched_lines))
911 return -EBUSY;
912
913 gpio_desc_to_lineinfo(desc, &lineinfo);
914
915 if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
916 clear_bit(lineinfo.line_offset, cdev->watched_lines);
917 return -EFAULT;
918 }
919
920 return 0;
921 } else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) {
922 if (copy_from_user(&offset, ip, sizeof(offset)))
923 return -EFAULT;
924
925 if (offset >= cdev->gdev->ngpio)
926 return -EINVAL;
927
928 if (!test_and_clear_bit(offset, cdev->watched_lines))
929 return -EBUSY;
930
931 return 0;
932 }
933 return -EINVAL;
934}
935
936#ifdef CONFIG_COMPAT
937static long gpio_ioctl_compat(struct file *file, unsigned int cmd,
938 unsigned long arg)
939{
940 return gpio_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
941}
942#endif
943
944static struct gpio_chardev_data *
945to_gpio_chardev_data(struct notifier_block *nb)
946{
947 return container_of(nb, struct gpio_chardev_data, lineinfo_changed_nb);
948}
949
950static int lineinfo_changed_notify(struct notifier_block *nb,
951 unsigned long action, void *data)
952{
953 struct gpio_chardev_data *cdev = to_gpio_chardev_data(nb);
954 struct gpioline_info_changed chg;
955 struct gpio_desc *desc = data;
956 int ret;
957
958 if (!test_bit(gpio_chip_hwgpio(desc), cdev->watched_lines))
959 return NOTIFY_DONE;
960
961 memset(&chg, 0, sizeof(chg));
962 chg.info.line_offset = gpio_chip_hwgpio(desc);
963 chg.event_type = action;
964 chg.timestamp = ktime_get_ns();
965 gpio_desc_to_lineinfo(desc, &chg.info);
966
967 ret = kfifo_in_spinlocked(&cdev->events, &chg, 1, &cdev->wait.lock);
968 if (ret)
969 wake_up_poll(&cdev->wait, EPOLLIN);
970 else
971 pr_debug_ratelimited("lineinfo event FIFO is full - event dropped\n");
972
973 return NOTIFY_OK;
974}
975
976static __poll_t lineinfo_watch_poll(struct file *file,
977 struct poll_table_struct *pollt)
978{
979 struct gpio_chardev_data *cdev = file->private_data;
980 __poll_t events = 0;
981
982 poll_wait(file, &cdev->wait, pollt);
983
984 if (!kfifo_is_empty_spinlocked_noirqsave(&cdev->events,
985 &cdev->wait.lock))
986 events = EPOLLIN | EPOLLRDNORM;
987
988 return events;
989}
990
991static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
992 size_t count, loff_t *off)
993{
994 struct gpio_chardev_data *cdev = file->private_data;
995 struct gpioline_info_changed event;
996 ssize_t bytes_read = 0;
997 int ret;
998
999 if (count < sizeof(event))
1000 return -EINVAL;
1001
1002 do {
1003 spin_lock(&cdev->wait.lock);
1004 if (kfifo_is_empty(&cdev->events)) {
1005 if (bytes_read) {
1006 spin_unlock(&cdev->wait.lock);
1007 return bytes_read;
1008 }
1009
1010 if (file->f_flags & O_NONBLOCK) {
1011 spin_unlock(&cdev->wait.lock);
1012 return -EAGAIN;
1013 }
1014
1015 ret = wait_event_interruptible_locked(cdev->wait,
1016 !kfifo_is_empty(&cdev->events));
1017 if (ret) {
1018 spin_unlock(&cdev->wait.lock);
1019 return ret;
1020 }
1021 }
1022
1023 ret = kfifo_out(&cdev->events, &event, 1);
1024 spin_unlock(&cdev->wait.lock);
1025 if (ret != 1) {
1026 ret = -EIO;
1027 break;
1028 /* We should never get here. See lineevent_read(). */
1029 }
1030
1031 if (copy_to_user(buf + bytes_read, &event, sizeof(event)))
1032 return -EFAULT;
1033 bytes_read += sizeof(event);
1034 } while (count >= bytes_read + sizeof(event));
1035
1036 return bytes_read;
1037}
1038
1039/**
1040 * gpio_chrdev_open() - open the chardev for ioctl operations
1041 * @inode: inode for this chardev
1042 * @file: file struct for storing private data
1043 * Returns 0 on success
1044 */
1045static int gpio_chrdev_open(struct inode *inode, struct file *file)
1046{
1047 struct gpio_device *gdev = container_of(inode->i_cdev,
1048 struct gpio_device, chrdev);
1049 struct gpio_chardev_data *cdev;
1050 int ret = -ENOMEM;
1051
1052 /* Fail on open if the backing gpiochip is gone */
1053 if (!gdev->chip)
1054 return -ENODEV;
1055
1056 cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
1057 if (!cdev)
1058 return -ENOMEM;
1059
1060 cdev->watched_lines = bitmap_zalloc(gdev->chip->ngpio, GFP_KERNEL);
1061 if (!cdev->watched_lines)
1062 goto out_free_cdev;
1063
1064 init_waitqueue_head(&cdev->wait);
1065 INIT_KFIFO(cdev->events);
1066 cdev->gdev = gdev;
1067
1068 cdev->lineinfo_changed_nb.notifier_call = lineinfo_changed_notify;
1069 ret = blocking_notifier_chain_register(&gdev->notifier,
1070 &cdev->lineinfo_changed_nb);
1071 if (ret)
1072 goto out_free_bitmap;
1073
1074 get_device(&gdev->dev);
1075 file->private_data = cdev;
1076
1077 ret = nonseekable_open(inode, file);
1078 if (ret)
1079 goto out_unregister_notifier;
1080
1081 return ret;
1082
1083out_unregister_notifier:
1084 blocking_notifier_chain_unregister(&gdev->notifier,
1085 &cdev->lineinfo_changed_nb);
1086out_free_bitmap:
1087 bitmap_free(cdev->watched_lines);
1088out_free_cdev:
1089 kfree(cdev);
1090 return ret;
1091}
1092
1093/**
1094 * gpio_chrdev_release() - close chardev after ioctl operations
1095 * @inode: inode for this chardev
1096 * @file: file struct for storing private data
1097 * Returns 0 on success
1098 */
1099static int gpio_chrdev_release(struct inode *inode, struct file *file)
1100{
1101 struct gpio_chardev_data *cdev = file->private_data;
1102 struct gpio_device *gdev = cdev->gdev;
1103
1104 bitmap_free(cdev->watched_lines);
1105 blocking_notifier_chain_unregister(&gdev->notifier,
1106 &cdev->lineinfo_changed_nb);
1107 put_device(&gdev->dev);
1108 kfree(cdev);
1109
1110 return 0;
1111}
1112
1113static const struct file_operations gpio_fileops = {
1114 .release = gpio_chrdev_release,
1115 .open = gpio_chrdev_open,
1116 .poll = lineinfo_watch_poll,
1117 .read = lineinfo_watch_read,
1118 .owner = THIS_MODULE,
1119 .llseek = no_llseek,
1120 .unlocked_ioctl = gpio_ioctl,
1121#ifdef CONFIG_COMPAT
1122 .compat_ioctl = gpio_ioctl_compat,
1123#endif
1124};
1125
1126int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
1127{
1128 int ret;
1129
1130 cdev_init(&gdev->chrdev, &gpio_fileops);
1131 gdev->chrdev.owner = THIS_MODULE;
1132 gdev->dev.devt = MKDEV(MAJOR(devt), gdev->id);
1133
1134 ret = cdev_device_add(&gdev->chrdev, &gdev->dev);
1135 if (ret)
1136 return ret;
1137
1138 chip_dbg(gdev->chip, "added GPIO chardev (%d:%d)\n",
1139 MAJOR(devt), gdev->id);
1140
1141 return 0;
1142}
1143
1144void gpiolib_cdev_unregister(struct gpio_device *gdev)
1145{
1146 cdev_device_del(&gdev->chrdev, &gdev->dev);
1147}