xref: /linux/drivers/gpio/gpiolib-cdev.c (revision 3fd6c59042dbba50391e30862beac979491145fe)
1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/anon_inodes.h>
4 #include <linux/atomic.h>
5 #include <linux/bitmap.h>
6 #include <linux/build_bug.h>
7 #include <linux/cdev.h>
8 #include <linux/cleanup.h>
9 #include <linux/compat.h>
10 #include <linux/compiler.h>
11 #include <linux/device.h>
12 #include <linux/err.h>
13 #include <linux/file.h>
14 #include <linux/gpio.h>
15 #include <linux/gpio/driver.h>
16 #include <linux/hte.h>
17 #include <linux/interrupt.h>
18 #include <linux/irqreturn.h>
19 #include <linux/kfifo.h>
20 #include <linux/module.h>
21 #include <linux/mutex.h>
22 #include <linux/overflow.h>
23 #include <linux/pinctrl/consumer.h>
24 #include <linux/poll.h>
25 #include <linux/seq_file.h>
26 #include <linux/spinlock.h>
27 #include <linux/string.h>
28 #include <linux/timekeeping.h>
29 #include <linux/uaccess.h>
30 #include <linux/workqueue.h>
31 
32 #include <uapi/linux/gpio.h>
33 
34 #include "gpiolib.h"
35 #include "gpiolib-cdev.h"
36 
37 /*
38  * Array sizes must ensure 64-bit alignment and not create holes in the
39  * struct packing.
40  */
41 static_assert(IS_ALIGNED(GPIO_V2_LINES_MAX, 2));
42 static_assert(IS_ALIGNED(GPIO_MAX_NAME_SIZE, 8));
43 
44 /*
45  * Check that uAPI structs are 64-bit aligned for 32/64-bit compatibility
46  */
47 static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_attribute), 8));
48 static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_config_attribute), 8));
49 static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_config), 8));
50 static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_request), 8));
51 static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_info), 8));
52 static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_info_changed), 8));
53 static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_event), 8));
54 static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_values), 8));
55 
56 /* Character device interface to GPIO.
57  *
58  * The GPIO character device, /dev/gpiochipN, provides userspace an
59  * interface to gpiolib GPIOs via ioctl()s.
60  */
61 
62 /*
63  * GPIO line handle management
64  */
65 
66 #ifdef CONFIG_GPIO_CDEV_V1
67 /**
68  * struct linehandle_state - contains the state of a userspace handle
69  * @gdev: the GPIO device the handle pertains to
70  * @label: consumer label used to tag descriptors
71  * @descs: the GPIO descriptors held by this handle
72  * @num_descs: the number of descriptors held in the descs array
73  */
74 struct linehandle_state {
75 	struct gpio_device *gdev;
76 	const char *label;
77 	struct gpio_desc *descs[GPIOHANDLES_MAX];
78 	u32 num_descs;
79 };
80 
81 #define GPIOHANDLE_REQUEST_VALID_FLAGS \
82 	(GPIOHANDLE_REQUEST_INPUT | \
83 	GPIOHANDLE_REQUEST_OUTPUT | \
84 	GPIOHANDLE_REQUEST_ACTIVE_LOW | \
85 	GPIOHANDLE_REQUEST_BIAS_PULL_UP | \
86 	GPIOHANDLE_REQUEST_BIAS_PULL_DOWN | \
87 	GPIOHANDLE_REQUEST_BIAS_DISABLE | \
88 	GPIOHANDLE_REQUEST_OPEN_DRAIN | \
89 	GPIOHANDLE_REQUEST_OPEN_SOURCE)
90 
91 #define GPIOHANDLE_REQUEST_DIRECTION_FLAGS \
92 	(GPIOHANDLE_REQUEST_INPUT | \
93 	 GPIOHANDLE_REQUEST_OUTPUT)
94 
linehandle_validate_flags(u32 flags)95 static int linehandle_validate_flags(u32 flags)
96 {
97 	/* Return an error if an unknown flag is set */
98 	if (flags & ~GPIOHANDLE_REQUEST_VALID_FLAGS)
99 		return -EINVAL;
100 
101 	/*
102 	 * Do not allow both INPUT & OUTPUT flags to be set as they are
103 	 * contradictory.
104 	 */
105 	if ((flags & GPIOHANDLE_REQUEST_INPUT) &&
106 	    (flags & GPIOHANDLE_REQUEST_OUTPUT))
107 		return -EINVAL;
108 
109 	/*
110 	 * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
111 	 * the hardware actually supports enabling both at the same time the
112 	 * electrical result would be disastrous.
113 	 */
114 	if ((flags & GPIOHANDLE_REQUEST_OPEN_DRAIN) &&
115 	    (flags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
116 		return -EINVAL;
117 
118 	/* OPEN_DRAIN and OPEN_SOURCE flags only make sense for output mode. */
119 	if (!(flags & GPIOHANDLE_REQUEST_OUTPUT) &&
120 	    ((flags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
121 	     (flags & GPIOHANDLE_REQUEST_OPEN_SOURCE)))
122 		return -EINVAL;
123 
124 	/* Bias flags only allowed for input or output mode. */
125 	if (!((flags & GPIOHANDLE_REQUEST_INPUT) ||
126 	      (flags & GPIOHANDLE_REQUEST_OUTPUT)) &&
127 	    ((flags & GPIOHANDLE_REQUEST_BIAS_DISABLE) ||
128 	     (flags & GPIOHANDLE_REQUEST_BIAS_PULL_UP) ||
129 	     (flags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN)))
130 		return -EINVAL;
131 
132 	/* Only one bias flag can be set. */
133 	if (((flags & GPIOHANDLE_REQUEST_BIAS_DISABLE) &&
134 	     (flags & (GPIOHANDLE_REQUEST_BIAS_PULL_DOWN |
135 		       GPIOHANDLE_REQUEST_BIAS_PULL_UP))) ||
136 	    ((flags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN) &&
137 	     (flags & GPIOHANDLE_REQUEST_BIAS_PULL_UP)))
138 		return -EINVAL;
139 
140 	return 0;
141 }
142 
linehandle_flags_to_desc_flags(u32 lflags,unsigned long * flagsp)143 static void linehandle_flags_to_desc_flags(u32 lflags, unsigned long *flagsp)
144 {
145 	unsigned long flags = READ_ONCE(*flagsp);
146 
147 	assign_bit(FLAG_ACTIVE_LOW, &flags,
148 		   lflags & GPIOHANDLE_REQUEST_ACTIVE_LOW);
149 	assign_bit(FLAG_OPEN_DRAIN, &flags,
150 		   lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN);
151 	assign_bit(FLAG_OPEN_SOURCE, &flags,
152 		   lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE);
153 	assign_bit(FLAG_PULL_UP, &flags,
154 		   lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP);
155 	assign_bit(FLAG_PULL_DOWN, &flags,
156 		   lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN);
157 	assign_bit(FLAG_BIAS_DISABLE, &flags,
158 		   lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE);
159 
160 	WRITE_ONCE(*flagsp, flags);
161 }
162 
linehandle_set_config(struct linehandle_state * lh,void __user * ip)163 static long linehandle_set_config(struct linehandle_state *lh,
164 				  void __user *ip)
165 {
166 	struct gpiohandle_config gcnf;
167 	struct gpio_desc *desc;
168 	int i, ret;
169 	u32 lflags;
170 
171 	if (copy_from_user(&gcnf, ip, sizeof(gcnf)))
172 		return -EFAULT;
173 
174 	lflags = gcnf.flags;
175 	ret = linehandle_validate_flags(lflags);
176 	if (ret)
177 		return ret;
178 
179 	/* Lines must be reconfigured explicitly as input or output. */
180 	if (!(lflags & GPIOHANDLE_REQUEST_DIRECTION_FLAGS))
181 		return -EINVAL;
182 
183 	for (i = 0; i < lh->num_descs; i++) {
184 		desc = lh->descs[i];
185 		linehandle_flags_to_desc_flags(lflags, &desc->flags);
186 
187 		if (lflags & GPIOHANDLE_REQUEST_OUTPUT) {
188 			int val = !!gcnf.default_values[i];
189 
190 			ret = gpiod_direction_output_nonotify(desc, val);
191 			if (ret)
192 				return ret;
193 		} else {
194 			ret = gpiod_direction_input_nonotify(desc);
195 			if (ret)
196 				return ret;
197 		}
198 
199 		gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_CONFIG);
200 	}
201 	return 0;
202 }
203 
linehandle_ioctl(struct file * file,unsigned int cmd,unsigned long arg)204 static long linehandle_ioctl(struct file *file, unsigned int cmd,
205 			     unsigned long arg)
206 {
207 	struct linehandle_state *lh = file->private_data;
208 	void __user *ip = (void __user *)arg;
209 	struct gpiohandle_data ghd;
210 	DECLARE_BITMAP(vals, GPIOHANDLES_MAX);
211 	unsigned int i;
212 	int ret;
213 
214 	guard(srcu)(&lh->gdev->srcu);
215 
216 	if (!rcu_access_pointer(lh->gdev->chip))
217 		return -ENODEV;
218 
219 	switch (cmd) {
220 	case GPIOHANDLE_GET_LINE_VALUES_IOCTL:
221 		/* NOTE: It's okay to read values of output lines */
222 		ret = gpiod_get_array_value_complex(false, true,
223 						    lh->num_descs, lh->descs,
224 						    NULL, vals);
225 		if (ret)
226 			return ret;
227 
228 		memset(&ghd, 0, sizeof(ghd));
229 		for (i = 0; i < lh->num_descs; i++)
230 			ghd.values[i] = test_bit(i, vals);
231 
232 		if (copy_to_user(ip, &ghd, sizeof(ghd)))
233 			return -EFAULT;
234 
235 		return 0;
236 	case GPIOHANDLE_SET_LINE_VALUES_IOCTL:
237 		/*
238 		 * All line descriptors were created at once with the same
239 		 * flags so just check if the first one is really output.
240 		 */
241 		if (!test_bit(FLAG_IS_OUT, &lh->descs[0]->flags))
242 			return -EPERM;
243 
244 		if (copy_from_user(&ghd, ip, sizeof(ghd)))
245 			return -EFAULT;
246 
247 		/* Clamp all values to [0,1] */
248 		for (i = 0; i < lh->num_descs; i++)
249 			__assign_bit(i, vals, ghd.values[i]);
250 
251 		/* Reuse the array setting function */
252 		return gpiod_set_array_value_complex(false,
253 						     true,
254 						     lh->num_descs,
255 						     lh->descs,
256 						     NULL,
257 						     vals);
258 	case GPIOHANDLE_SET_CONFIG_IOCTL:
259 		return linehandle_set_config(lh, ip);
260 	default:
261 		return -EINVAL;
262 	}
263 }
264 
265 #ifdef CONFIG_COMPAT
linehandle_ioctl_compat(struct file * file,unsigned int cmd,unsigned long arg)266 static long linehandle_ioctl_compat(struct file *file, unsigned int cmd,
267 				    unsigned long arg)
268 {
269 	return linehandle_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
270 }
271 #endif
272 
linehandle_free(struct linehandle_state * lh)273 static void linehandle_free(struct linehandle_state *lh)
274 {
275 	int i;
276 
277 	for (i = 0; i < lh->num_descs; i++)
278 		if (lh->descs[i])
279 			gpiod_free(lh->descs[i]);
280 	kfree(lh->label);
281 	gpio_device_put(lh->gdev);
282 	kfree(lh);
283 }
284 
linehandle_release(struct inode * inode,struct file * file)285 static int linehandle_release(struct inode *inode, struct file *file)
286 {
287 	linehandle_free(file->private_data);
288 	return 0;
289 }
290 
291 static const struct file_operations linehandle_fileops = {
292 	.release = linehandle_release,
293 	.owner = THIS_MODULE,
294 	.llseek = noop_llseek,
295 	.unlocked_ioctl = linehandle_ioctl,
296 #ifdef CONFIG_COMPAT
297 	.compat_ioctl = linehandle_ioctl_compat,
298 #endif
299 };
300 
linehandle_create(struct gpio_device * gdev,void __user * ip)301 static int linehandle_create(struct gpio_device *gdev, void __user *ip)
302 {
303 	struct gpiohandle_request handlereq;
304 	struct linehandle_state *lh;
305 	struct file *file;
306 	int fd, i, ret;
307 	u32 lflags;
308 
309 	if (copy_from_user(&handlereq, ip, sizeof(handlereq)))
310 		return -EFAULT;
311 	if ((handlereq.lines == 0) || (handlereq.lines > GPIOHANDLES_MAX))
312 		return -EINVAL;
313 
314 	lflags = handlereq.flags;
315 
316 	ret = linehandle_validate_flags(lflags);
317 	if (ret)
318 		return ret;
319 
320 	lh = kzalloc(sizeof(*lh), GFP_KERNEL);
321 	if (!lh)
322 		return -ENOMEM;
323 	lh->gdev = gpio_device_get(gdev);
324 
325 	if (handlereq.consumer_label[0] != '\0') {
326 		/* label is only initialized if consumer_label is set */
327 		lh->label = kstrndup(handlereq.consumer_label,
328 				     sizeof(handlereq.consumer_label) - 1,
329 				     GFP_KERNEL);
330 		if (!lh->label) {
331 			ret = -ENOMEM;
332 			goto out_free_lh;
333 		}
334 	}
335 
336 	lh->num_descs = handlereq.lines;
337 
338 	/* Request each GPIO */
339 	for (i = 0; i < handlereq.lines; i++) {
340 		u32 offset = handlereq.lineoffsets[i];
341 		struct gpio_desc *desc = gpio_device_get_desc(gdev, offset);
342 
343 		if (IS_ERR(desc)) {
344 			ret = PTR_ERR(desc);
345 			goto out_free_lh;
346 		}
347 
348 		ret = gpiod_request_user(desc, lh->label);
349 		if (ret)
350 			goto out_free_lh;
351 		lh->descs[i] = desc;
352 		linehandle_flags_to_desc_flags(handlereq.flags, &desc->flags);
353 
354 		ret = gpiod_set_transitory(desc, false);
355 		if (ret < 0)
356 			goto out_free_lh;
357 
358 		/*
359 		 * Lines have to be requested explicitly for input
360 		 * or output, else the line will be treated "as is".
361 		 */
362 		if (lflags & GPIOHANDLE_REQUEST_OUTPUT) {
363 			int val = !!handlereq.default_values[i];
364 
365 			ret = gpiod_direction_output_nonotify(desc, val);
366 			if (ret)
367 				goto out_free_lh;
368 		} else if (lflags & GPIOHANDLE_REQUEST_INPUT) {
369 			ret = gpiod_direction_input_nonotify(desc);
370 			if (ret)
371 				goto out_free_lh;
372 		}
373 
374 		gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_REQUESTED);
375 
376 		dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
377 			offset);
378 	}
379 
380 	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
381 	if (fd < 0) {
382 		ret = fd;
383 		goto out_free_lh;
384 	}
385 
386 	file = anon_inode_getfile("gpio-linehandle",
387 				  &linehandle_fileops,
388 				  lh,
389 				  O_RDONLY | O_CLOEXEC);
390 	if (IS_ERR(file)) {
391 		ret = PTR_ERR(file);
392 		goto out_put_unused_fd;
393 	}
394 
395 	handlereq.fd = fd;
396 	if (copy_to_user(ip, &handlereq, sizeof(handlereq))) {
397 		/*
398 		 * fput() will trigger the release() callback, so do not go onto
399 		 * the regular error cleanup path here.
400 		 */
401 		fput(file);
402 		put_unused_fd(fd);
403 		return -EFAULT;
404 	}
405 
406 	fd_install(fd, file);
407 
408 	dev_dbg(&gdev->dev, "registered chardev handle for %d lines\n",
409 		lh->num_descs);
410 
411 	return 0;
412 
413 out_put_unused_fd:
414 	put_unused_fd(fd);
415 out_free_lh:
416 	linehandle_free(lh);
417 	return ret;
418 }
419 #endif /* CONFIG_GPIO_CDEV_V1 */
420 
421 /**
422  * struct line - contains the state of a requested line
423  * @desc: the GPIO descriptor for this line.
424  * @req: the corresponding line request
425  * @irq: the interrupt triggered in response to events on this GPIO
426  * @edflags: the edge flags, GPIO_V2_LINE_FLAG_EDGE_RISING and/or
427  * GPIO_V2_LINE_FLAG_EDGE_FALLING, indicating the edge detection applied
428  * @timestamp_ns: cache for the timestamp storing it between hardirq and
429  * IRQ thread, used to bring the timestamp close to the actual event
430  * @req_seqno: the seqno for the current edge event in the sequence of
431  * events for the corresponding line request. This is drawn from the @req.
432  * @line_seqno: the seqno for the current edge event in the sequence of
433  * events for this line.
434  * @work: the worker that implements software debouncing
435  * @sw_debounced: flag indicating if the software debouncer is active
436  * @level: the current debounced physical level of the line
437  * @hdesc: the Hardware Timestamp Engine (HTE) descriptor
438  * @raw_level: the line level at the time of event
439  * @total_discard_seq: the running counter of the discarded events
440  * @last_seqno: the last sequence number before debounce period expires
441  */
442 struct line {
443 	struct gpio_desc *desc;
444 	/*
445 	 * -- edge detector specific fields --
446 	 */
447 	struct linereq *req;
448 	unsigned int irq;
449 	/*
450 	 * The flags for the active edge detector configuration.
451 	 *
452 	 * edflags is set by linereq_create(), linereq_free(), and
453 	 * linereq_set_config(), which are themselves mutually
454 	 * exclusive, and is accessed by edge_irq_thread(),
455 	 * process_hw_ts_thread() and debounce_work_func(),
456 	 * which can all live with a slightly stale value.
457 	 */
458 	u64 edflags;
459 	/*
460 	 * timestamp_ns and req_seqno are accessed only by
461 	 * edge_irq_handler() and edge_irq_thread(), which are themselves
462 	 * mutually exclusive, so no additional protection is necessary.
463 	 */
464 	u64 timestamp_ns;
465 	u32 req_seqno;
466 	/*
467 	 * line_seqno is accessed by either edge_irq_thread() or
468 	 * debounce_work_func(), which are themselves mutually exclusive,
469 	 * so no additional protection is necessary.
470 	 */
471 	u32 line_seqno;
472 	/*
473 	 * -- debouncer specific fields --
474 	 */
475 	struct delayed_work work;
476 	/*
477 	 * sw_debounce is accessed by linereq_set_config(), which is the
478 	 * only setter, and linereq_get_values(), which can live with a
479 	 * slightly stale value.
480 	 */
481 	unsigned int sw_debounced;
482 	/*
483 	 * level is accessed by debounce_work_func(), which is the only
484 	 * setter, and linereq_get_values() which can live with a slightly
485 	 * stale value.
486 	 */
487 	unsigned int level;
488 #ifdef CONFIG_HTE
489 	struct hte_ts_desc hdesc;
490 	/*
491 	 * HTE provider sets line level at the time of event. The valid
492 	 * value is 0 or 1 and negative value for an error.
493 	 */
494 	int raw_level;
495 	/*
496 	 * when sw_debounce is set on HTE enabled line, this is running
497 	 * counter of the discarded events.
498 	 */
499 	u32 total_discard_seq;
500 	/*
501 	 * when sw_debounce is set on HTE enabled line, this variable records
502 	 * last sequence number before debounce period expires.
503 	 */
504 	u32 last_seqno;
505 #endif /* CONFIG_HTE */
506 };
507 
508 /**
509  * struct linereq - contains the state of a userspace line request
510  * @gdev: the GPIO device the line request pertains to
511  * @label: consumer label used to tag GPIO descriptors
512  * @num_lines: the number of lines in the lines array
513  * @wait: wait queue that handles blocking reads of events
514  * @device_unregistered_nb: notifier block for receiving gdev unregister events
515  * @event_buffer_size: the number of elements allocated in @events
516  * @events: KFIFO for the GPIO events
517  * @seqno: the sequence number for edge events generated on all lines in
518  * this line request.  Note that this is not used when @num_lines is 1, as
519  * the line_seqno is then the same and is cheaper to calculate.
520  * @config_mutex: mutex for serializing ioctl() calls to ensure consistency
521  * of configuration, particularly multi-step accesses to desc flags.
522  * @lines: the lines held by this line request, with @num_lines elements.
523  */
524 struct linereq {
525 	struct gpio_device *gdev;
526 	const char *label;
527 	u32 num_lines;
528 	wait_queue_head_t wait;
529 	struct notifier_block device_unregistered_nb;
530 	u32 event_buffer_size;
531 	DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event);
532 	atomic_t seqno;
533 	struct mutex config_mutex;
534 	struct line lines[] __counted_by(num_lines);
535 };
536 
537 #define GPIO_V2_LINE_BIAS_FLAGS \
538 	(GPIO_V2_LINE_FLAG_BIAS_PULL_UP | \
539 	 GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN | \
540 	 GPIO_V2_LINE_FLAG_BIAS_DISABLED)
541 
542 #define GPIO_V2_LINE_DIRECTION_FLAGS \
543 	(GPIO_V2_LINE_FLAG_INPUT | \
544 	 GPIO_V2_LINE_FLAG_OUTPUT)
545 
546 #define GPIO_V2_LINE_DRIVE_FLAGS \
547 	(GPIO_V2_LINE_FLAG_OPEN_DRAIN | \
548 	 GPIO_V2_LINE_FLAG_OPEN_SOURCE)
549 
550 #define GPIO_V2_LINE_EDGE_FLAGS \
551 	(GPIO_V2_LINE_FLAG_EDGE_RISING | \
552 	 GPIO_V2_LINE_FLAG_EDGE_FALLING)
553 
554 #define GPIO_V2_LINE_FLAG_EDGE_BOTH GPIO_V2_LINE_EDGE_FLAGS
555 
556 #define GPIO_V2_LINE_VALID_FLAGS \
557 	(GPIO_V2_LINE_FLAG_ACTIVE_LOW | \
558 	 GPIO_V2_LINE_DIRECTION_FLAGS | \
559 	 GPIO_V2_LINE_DRIVE_FLAGS | \
560 	 GPIO_V2_LINE_EDGE_FLAGS | \
561 	 GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME | \
562 	 GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE | \
563 	 GPIO_V2_LINE_BIAS_FLAGS)
564 
565 /* subset of flags relevant for edge detector configuration */
566 #define GPIO_V2_LINE_EDGE_DETECTOR_FLAGS \
567 	(GPIO_V2_LINE_FLAG_ACTIVE_LOW | \
568 	 GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE | \
569 	 GPIO_V2_LINE_EDGE_FLAGS)
570 
linereq_unregistered_notify(struct notifier_block * nb,unsigned long action,void * data)571 static int linereq_unregistered_notify(struct notifier_block *nb,
572 				       unsigned long action, void *data)
573 {
574 	struct linereq *lr = container_of(nb, struct linereq,
575 					  device_unregistered_nb);
576 
577 	wake_up_poll(&lr->wait, EPOLLIN | EPOLLERR);
578 
579 	return NOTIFY_OK;
580 }
581 
linereq_put_event(struct linereq * lr,struct gpio_v2_line_event * le)582 static void linereq_put_event(struct linereq *lr,
583 			      struct gpio_v2_line_event *le)
584 {
585 	bool overflow = false;
586 
587 	scoped_guard(spinlock, &lr->wait.lock) {
588 		if (kfifo_is_full(&lr->events)) {
589 			overflow = true;
590 			kfifo_skip(&lr->events);
591 		}
592 		kfifo_in(&lr->events, le, 1);
593 	}
594 	if (!overflow)
595 		wake_up_poll(&lr->wait, EPOLLIN);
596 	else
597 		pr_debug_ratelimited("event FIFO is full - event dropped\n");
598 }
599 
line_event_timestamp(struct line * line)600 static u64 line_event_timestamp(struct line *line)
601 {
602 	if (test_bit(FLAG_EVENT_CLOCK_REALTIME, &line->desc->flags))
603 		return ktime_get_real_ns();
604 	else if (IS_ENABLED(CONFIG_HTE) &&
605 		 test_bit(FLAG_EVENT_CLOCK_HTE, &line->desc->flags))
606 		return line->timestamp_ns;
607 
608 	return ktime_get_ns();
609 }
610 
line_event_id(int level)611 static u32 line_event_id(int level)
612 {
613 	return level ? GPIO_V2_LINE_EVENT_RISING_EDGE :
614 		       GPIO_V2_LINE_EVENT_FALLING_EDGE;
615 }
616 
make_irq_label(const char * orig)617 static inline char *make_irq_label(const char *orig)
618 {
619 	char *new;
620 
621 	if (!orig)
622 		return NULL;
623 
624 	new = kstrdup_and_replace(orig, '/', ':', GFP_KERNEL);
625 	if (!new)
626 		return ERR_PTR(-ENOMEM);
627 
628 	return new;
629 }
630 
free_irq_label(const char * label)631 static inline void free_irq_label(const char *label)
632 {
633 	kfree(label);
634 }
635 
636 #ifdef CONFIG_HTE
637 
process_hw_ts_thread(void * p)638 static enum hte_return process_hw_ts_thread(void *p)
639 {
640 	struct line *line;
641 	struct linereq *lr;
642 	struct gpio_v2_line_event le;
643 	u64 edflags;
644 	int level;
645 
646 	if (!p)
647 		return HTE_CB_HANDLED;
648 
649 	line = p;
650 	lr = line->req;
651 
652 	memset(&le, 0, sizeof(le));
653 
654 	le.timestamp_ns = line->timestamp_ns;
655 	edflags = READ_ONCE(line->edflags);
656 
657 	switch (edflags & GPIO_V2_LINE_EDGE_FLAGS) {
658 	case GPIO_V2_LINE_FLAG_EDGE_BOTH:
659 		level = (line->raw_level >= 0) ?
660 				line->raw_level :
661 				gpiod_get_raw_value_cansleep(line->desc);
662 
663 		if (edflags & GPIO_V2_LINE_FLAG_ACTIVE_LOW)
664 			level = !level;
665 
666 		le.id = line_event_id(level);
667 		break;
668 	case GPIO_V2_LINE_FLAG_EDGE_RISING:
669 		le.id = GPIO_V2_LINE_EVENT_RISING_EDGE;
670 		break;
671 	case GPIO_V2_LINE_FLAG_EDGE_FALLING:
672 		le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE;
673 		break;
674 	default:
675 		return HTE_CB_HANDLED;
676 	}
677 	le.line_seqno = line->line_seqno;
678 	le.seqno = (lr->num_lines == 1) ? le.line_seqno : line->req_seqno;
679 	le.offset = gpio_chip_hwgpio(line->desc);
680 
681 	linereq_put_event(lr, &le);
682 
683 	return HTE_CB_HANDLED;
684 }
685 
process_hw_ts(struct hte_ts_data * ts,void * p)686 static enum hte_return process_hw_ts(struct hte_ts_data *ts, void *p)
687 {
688 	struct line *line;
689 	struct linereq *lr;
690 	int diff_seqno = 0;
691 
692 	if (!ts || !p)
693 		return HTE_CB_HANDLED;
694 
695 	line = p;
696 	line->timestamp_ns = ts->tsc;
697 	line->raw_level = ts->raw_level;
698 	lr = line->req;
699 
700 	if (READ_ONCE(line->sw_debounced)) {
701 		line->total_discard_seq++;
702 		line->last_seqno = ts->seq;
703 		mod_delayed_work(system_wq, &line->work,
704 		  usecs_to_jiffies(READ_ONCE(line->desc->debounce_period_us)));
705 	} else {
706 		if (unlikely(ts->seq < line->line_seqno))
707 			return HTE_CB_HANDLED;
708 
709 		diff_seqno = ts->seq - line->line_seqno;
710 		line->line_seqno = ts->seq;
711 		if (lr->num_lines != 1)
712 			line->req_seqno = atomic_add_return(diff_seqno,
713 							    &lr->seqno);
714 
715 		return HTE_RUN_SECOND_CB;
716 	}
717 
718 	return HTE_CB_HANDLED;
719 }
720 
hte_edge_setup(struct line * line,u64 eflags)721 static int hte_edge_setup(struct line *line, u64 eflags)
722 {
723 	int ret;
724 	unsigned long flags = 0;
725 	struct hte_ts_desc *hdesc = &line->hdesc;
726 
727 	if (eflags & GPIO_V2_LINE_FLAG_EDGE_RISING)
728 		flags |= test_bit(FLAG_ACTIVE_LOW, &line->desc->flags) ?
729 				 HTE_FALLING_EDGE_TS :
730 				 HTE_RISING_EDGE_TS;
731 	if (eflags & GPIO_V2_LINE_FLAG_EDGE_FALLING)
732 		flags |= test_bit(FLAG_ACTIVE_LOW, &line->desc->flags) ?
733 				 HTE_RISING_EDGE_TS :
734 				 HTE_FALLING_EDGE_TS;
735 
736 	line->total_discard_seq = 0;
737 
738 	hte_init_line_attr(hdesc, desc_to_gpio(line->desc), flags, NULL,
739 			   line->desc);
740 
741 	ret = hte_ts_get(NULL, hdesc, 0);
742 	if (ret)
743 		return ret;
744 
745 	return hte_request_ts_ns(hdesc, process_hw_ts, process_hw_ts_thread,
746 				 line);
747 }
748 
749 #else
750 
hte_edge_setup(struct line * line,u64 eflags)751 static int hte_edge_setup(struct line *line, u64 eflags)
752 {
753 	return 0;
754 }
755 #endif /* CONFIG_HTE */
756 
edge_irq_thread(int irq,void * p)757 static irqreturn_t edge_irq_thread(int irq, void *p)
758 {
759 	struct line *line = p;
760 	struct linereq *lr = line->req;
761 	struct gpio_v2_line_event le;
762 
763 	/* Do not leak kernel stack to userspace */
764 	memset(&le, 0, sizeof(le));
765 
766 	if (line->timestamp_ns) {
767 		le.timestamp_ns = line->timestamp_ns;
768 	} else {
769 		/*
770 		 * We may be running from a nested threaded interrupt in
771 		 * which case we didn't get the timestamp from
772 		 * edge_irq_handler().
773 		 */
774 		le.timestamp_ns = line_event_timestamp(line);
775 		if (lr->num_lines != 1)
776 			line->req_seqno = atomic_inc_return(&lr->seqno);
777 	}
778 	line->timestamp_ns = 0;
779 
780 	switch (READ_ONCE(line->edflags) & GPIO_V2_LINE_EDGE_FLAGS) {
781 	case GPIO_V2_LINE_FLAG_EDGE_BOTH:
782 		le.id = line_event_id(gpiod_get_value_cansleep(line->desc));
783 		break;
784 	case GPIO_V2_LINE_FLAG_EDGE_RISING:
785 		le.id = GPIO_V2_LINE_EVENT_RISING_EDGE;
786 		break;
787 	case GPIO_V2_LINE_FLAG_EDGE_FALLING:
788 		le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE;
789 		break;
790 	default:
791 		return IRQ_NONE;
792 	}
793 	line->line_seqno++;
794 	le.line_seqno = line->line_seqno;
795 	le.seqno = (lr->num_lines == 1) ? le.line_seqno : line->req_seqno;
796 	le.offset = gpio_chip_hwgpio(line->desc);
797 
798 	linereq_put_event(lr, &le);
799 
800 	return IRQ_HANDLED;
801 }
802 
edge_irq_handler(int irq,void * p)803 static irqreturn_t edge_irq_handler(int irq, void *p)
804 {
805 	struct line *line = p;
806 	struct linereq *lr = line->req;
807 
808 	/*
809 	 * Just store the timestamp in hardirq context so we get it as
810 	 * close in time as possible to the actual event.
811 	 */
812 	line->timestamp_ns = line_event_timestamp(line);
813 
814 	if (lr->num_lines != 1)
815 		line->req_seqno = atomic_inc_return(&lr->seqno);
816 
817 	return IRQ_WAKE_THREAD;
818 }
819 
820 /*
821  * returns the current debounced logical value.
822  */
debounced_value(struct line * line)823 static bool debounced_value(struct line *line)
824 {
825 	bool value;
826 
827 	/*
828 	 * minor race - debouncer may be stopped here, so edge_detector_stop()
829 	 * must leave the value unchanged so the following will read the level
830 	 * from when the debouncer was last running.
831 	 */
832 	value = READ_ONCE(line->level);
833 
834 	if (test_bit(FLAG_ACTIVE_LOW, &line->desc->flags))
835 		value = !value;
836 
837 	return value;
838 }
839 
debounce_irq_handler(int irq,void * p)840 static irqreturn_t debounce_irq_handler(int irq, void *p)
841 {
842 	struct line *line = p;
843 
844 	mod_delayed_work(system_wq, &line->work,
845 		usecs_to_jiffies(READ_ONCE(line->desc->debounce_period_us)));
846 
847 	return IRQ_HANDLED;
848 }
849 
debounce_work_func(struct work_struct * work)850 static void debounce_work_func(struct work_struct *work)
851 {
852 	struct gpio_v2_line_event le;
853 	struct line *line = container_of(work, struct line, work.work);
854 	struct linereq *lr;
855 	u64 eflags, edflags = READ_ONCE(line->edflags);
856 	int level = -1;
857 #ifdef CONFIG_HTE
858 	int diff_seqno;
859 
860 	if (edflags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE)
861 		level = line->raw_level;
862 #endif
863 	if (level < 0)
864 		level = gpiod_get_raw_value_cansleep(line->desc);
865 	if (level < 0) {
866 		pr_debug_ratelimited("debouncer failed to read line value\n");
867 		return;
868 	}
869 
870 	if (READ_ONCE(line->level) == level)
871 		return;
872 
873 	WRITE_ONCE(line->level, level);
874 
875 	/* -- edge detection -- */
876 	eflags = edflags & GPIO_V2_LINE_EDGE_FLAGS;
877 	if (!eflags)
878 		return;
879 
880 	/* switch from physical level to logical - if they differ */
881 	if (edflags & GPIO_V2_LINE_FLAG_ACTIVE_LOW)
882 		level = !level;
883 
884 	/* ignore edges that are not being monitored */
885 	if (((eflags == GPIO_V2_LINE_FLAG_EDGE_RISING) && !level) ||
886 	    ((eflags == GPIO_V2_LINE_FLAG_EDGE_FALLING) && level))
887 		return;
888 
889 	/* Do not leak kernel stack to userspace */
890 	memset(&le, 0, sizeof(le));
891 
892 	lr = line->req;
893 	le.timestamp_ns = line_event_timestamp(line);
894 	le.offset = gpio_chip_hwgpio(line->desc);
895 #ifdef CONFIG_HTE
896 	if (edflags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE) {
897 		/* discard events except the last one */
898 		line->total_discard_seq -= 1;
899 		diff_seqno = line->last_seqno - line->total_discard_seq -
900 				line->line_seqno;
901 		line->line_seqno = line->last_seqno - line->total_discard_seq;
902 		le.line_seqno = line->line_seqno;
903 		le.seqno = (lr->num_lines == 1) ?
904 			le.line_seqno : atomic_add_return(diff_seqno, &lr->seqno);
905 	} else
906 #endif /* CONFIG_HTE */
907 	{
908 		line->line_seqno++;
909 		le.line_seqno = line->line_seqno;
910 		le.seqno = (lr->num_lines == 1) ?
911 			le.line_seqno : atomic_inc_return(&lr->seqno);
912 	}
913 
914 	le.id = line_event_id(level);
915 
916 	linereq_put_event(lr, &le);
917 }
918 
debounce_setup(struct line * line,unsigned int debounce_period_us)919 static int debounce_setup(struct line *line, unsigned int debounce_period_us)
920 {
921 	unsigned long irqflags;
922 	int ret, level, irq;
923 	char *label;
924 
925 	/*
926 	 * Try hardware. Skip gpiod_set_config() to avoid emitting two
927 	 * CHANGED_CONFIG line state events.
928 	 */
929 	ret = gpio_do_set_config(line->desc,
930 			pinconf_to_config_packed(PIN_CONFIG_INPUT_DEBOUNCE,
931 						 debounce_period_us));
932 	if (ret != -ENOTSUPP)
933 		return ret;
934 
935 	if (debounce_period_us) {
936 		/* setup software debounce */
937 		level = gpiod_get_raw_value_cansleep(line->desc);
938 		if (level < 0)
939 			return level;
940 
941 		if (!(IS_ENABLED(CONFIG_HTE) &&
942 		      test_bit(FLAG_EVENT_CLOCK_HTE, &line->desc->flags))) {
943 			irq = gpiod_to_irq(line->desc);
944 			if (irq < 0)
945 				return -ENXIO;
946 
947 			label = make_irq_label(line->req->label);
948 			if (IS_ERR(label))
949 				return -ENOMEM;
950 
951 			irqflags = IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING;
952 			ret = request_irq(irq, debounce_irq_handler, irqflags,
953 					  label, line);
954 			if (ret) {
955 				free_irq_label(label);
956 				return ret;
957 			}
958 			line->irq = irq;
959 		} else {
960 			ret = hte_edge_setup(line, GPIO_V2_LINE_FLAG_EDGE_BOTH);
961 			if (ret)
962 				return ret;
963 		}
964 
965 		WRITE_ONCE(line->level, level);
966 		WRITE_ONCE(line->sw_debounced, 1);
967 	}
968 	return 0;
969 }
970 
gpio_v2_line_config_debounced(struct gpio_v2_line_config * lc,unsigned int line_idx)971 static bool gpio_v2_line_config_debounced(struct gpio_v2_line_config *lc,
972 					  unsigned int line_idx)
973 {
974 	unsigned int i;
975 	u64 mask = BIT_ULL(line_idx);
976 
977 	for (i = 0; i < lc->num_attrs; i++) {
978 		if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_DEBOUNCE) &&
979 		    (lc->attrs[i].mask & mask))
980 			return true;
981 	}
982 	return false;
983 }
984 
gpio_v2_line_config_debounce_period(struct gpio_v2_line_config * lc,unsigned int line_idx)985 static u32 gpio_v2_line_config_debounce_period(struct gpio_v2_line_config *lc,
986 					       unsigned int line_idx)
987 {
988 	unsigned int i;
989 	u64 mask = BIT_ULL(line_idx);
990 
991 	for (i = 0; i < lc->num_attrs; i++) {
992 		if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_DEBOUNCE) &&
993 		    (lc->attrs[i].mask & mask))
994 			return lc->attrs[i].attr.debounce_period_us;
995 	}
996 	return 0;
997 }
998 
edge_detector_stop(struct line * line)999 static void edge_detector_stop(struct line *line)
1000 {
1001 	if (line->irq) {
1002 		free_irq_label(free_irq(line->irq, line));
1003 		line->irq = 0;
1004 	}
1005 
1006 #ifdef CONFIG_HTE
1007 	if (READ_ONCE(line->edflags) & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE)
1008 		hte_ts_put(&line->hdesc);
1009 #endif
1010 
1011 	cancel_delayed_work_sync(&line->work);
1012 	WRITE_ONCE(line->sw_debounced, 0);
1013 	WRITE_ONCE(line->edflags, 0);
1014 	if (line->desc)
1015 		WRITE_ONCE(line->desc->debounce_period_us, 0);
1016 	/* do not change line->level - see comment in debounced_value() */
1017 }
1018 
edge_detector_fifo_init(struct linereq * req)1019 static int edge_detector_fifo_init(struct linereq *req)
1020 {
1021 	if (kfifo_initialized(&req->events))
1022 		return 0;
1023 
1024 	return kfifo_alloc(&req->events, req->event_buffer_size, GFP_KERNEL);
1025 }
1026 
edge_detector_setup(struct line * line,struct gpio_v2_line_config * lc,unsigned int line_idx,u64 edflags)1027 static int edge_detector_setup(struct line *line,
1028 			       struct gpio_v2_line_config *lc,
1029 			       unsigned int line_idx, u64 edflags)
1030 {
1031 	u32 debounce_period_us;
1032 	unsigned long irqflags = 0;
1033 	u64 eflags;
1034 	int irq, ret;
1035 	char *label;
1036 
1037 	eflags = edflags & GPIO_V2_LINE_EDGE_FLAGS;
1038 	if (eflags) {
1039 		ret = edge_detector_fifo_init(line->req);
1040 		if (ret)
1041 			return ret;
1042 	}
1043 	if (gpio_v2_line_config_debounced(lc, line_idx)) {
1044 		debounce_period_us = gpio_v2_line_config_debounce_period(lc, line_idx);
1045 		ret = debounce_setup(line, debounce_period_us);
1046 		if (ret)
1047 			return ret;
1048 		WRITE_ONCE(line->desc->debounce_period_us, debounce_period_us);
1049 	}
1050 
1051 	/* detection disabled or sw debouncer will provide edge detection */
1052 	if (!eflags || READ_ONCE(line->sw_debounced))
1053 		return 0;
1054 
1055 	if (IS_ENABLED(CONFIG_HTE) &&
1056 	    (edflags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE))
1057 		return hte_edge_setup(line, edflags);
1058 
1059 	irq = gpiod_to_irq(line->desc);
1060 	if (irq < 0)
1061 		return -ENXIO;
1062 
1063 	if (eflags & GPIO_V2_LINE_FLAG_EDGE_RISING)
1064 		irqflags |= test_bit(FLAG_ACTIVE_LOW, &line->desc->flags) ?
1065 			IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
1066 	if (eflags & GPIO_V2_LINE_FLAG_EDGE_FALLING)
1067 		irqflags |= test_bit(FLAG_ACTIVE_LOW, &line->desc->flags) ?
1068 			IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
1069 	irqflags |= IRQF_ONESHOT;
1070 
1071 	label = make_irq_label(line->req->label);
1072 	if (IS_ERR(label))
1073 		return PTR_ERR(label);
1074 
1075 	/* Request a thread to read the events */
1076 	ret = request_threaded_irq(irq, edge_irq_handler, edge_irq_thread,
1077 				   irqflags, label, line);
1078 	if (ret) {
1079 		free_irq_label(label);
1080 		return ret;
1081 	}
1082 
1083 	line->irq = irq;
1084 	return 0;
1085 }
1086 
edge_detector_update(struct line * line,struct gpio_v2_line_config * lc,unsigned int line_idx,u64 edflags)1087 static int edge_detector_update(struct line *line,
1088 				struct gpio_v2_line_config *lc,
1089 				unsigned int line_idx, u64 edflags)
1090 {
1091 	u64 active_edflags = READ_ONCE(line->edflags);
1092 	unsigned int debounce_period_us =
1093 			gpio_v2_line_config_debounce_period(lc, line_idx);
1094 
1095 	if ((active_edflags == edflags) &&
1096 	    (READ_ONCE(line->desc->debounce_period_us) == debounce_period_us))
1097 		return 0;
1098 
1099 	/* sw debounced and still will be...*/
1100 	if (debounce_period_us && READ_ONCE(line->sw_debounced)) {
1101 		WRITE_ONCE(line->desc->debounce_period_us, debounce_period_us);
1102 		/*
1103 		 * ensure event fifo is initialised if edge detection
1104 		 * is now enabled.
1105 		 */
1106 		if (edflags & GPIO_V2_LINE_EDGE_FLAGS)
1107 			return edge_detector_fifo_init(line->req);
1108 
1109 		return 0;
1110 	}
1111 
1112 	/* reconfiguring edge detection or sw debounce being disabled */
1113 	if ((line->irq && !READ_ONCE(line->sw_debounced)) ||
1114 	    (active_edflags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE) ||
1115 	    (!debounce_period_us && READ_ONCE(line->sw_debounced)))
1116 		edge_detector_stop(line);
1117 
1118 	return edge_detector_setup(line, lc, line_idx, edflags);
1119 }
1120 
gpio_v2_line_config_flags(struct gpio_v2_line_config * lc,unsigned int line_idx)1121 static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,
1122 				     unsigned int line_idx)
1123 {
1124 	unsigned int i;
1125 	u64 mask = BIT_ULL(line_idx);
1126 
1127 	for (i = 0; i < lc->num_attrs; i++) {
1128 		if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_FLAGS) &&
1129 		    (lc->attrs[i].mask & mask))
1130 			return lc->attrs[i].attr.flags;
1131 	}
1132 	return lc->flags;
1133 }
1134 
gpio_v2_line_config_output_value(struct gpio_v2_line_config * lc,unsigned int line_idx)1135 static int gpio_v2_line_config_output_value(struct gpio_v2_line_config *lc,
1136 					    unsigned int line_idx)
1137 {
1138 	unsigned int i;
1139 	u64 mask = BIT_ULL(line_idx);
1140 
1141 	for (i = 0; i < lc->num_attrs; i++) {
1142 		if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES) &&
1143 		    (lc->attrs[i].mask & mask))
1144 			return !!(lc->attrs[i].attr.values & mask);
1145 	}
1146 	return 0;
1147 }
1148 
gpio_v2_line_flags_validate(u64 flags)1149 static int gpio_v2_line_flags_validate(u64 flags)
1150 {
1151 	/* Return an error if an unknown flag is set */
1152 	if (flags & ~GPIO_V2_LINE_VALID_FLAGS)
1153 		return -EINVAL;
1154 
1155 	if (!IS_ENABLED(CONFIG_HTE) &&
1156 	    (flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE))
1157 		return -EOPNOTSUPP;
1158 
1159 	/*
1160 	 * Do not allow both INPUT and OUTPUT flags to be set as they are
1161 	 * contradictory.
1162 	 */
1163 	if ((flags & GPIO_V2_LINE_FLAG_INPUT) &&
1164 	    (flags & GPIO_V2_LINE_FLAG_OUTPUT))
1165 		return -EINVAL;
1166 
1167 	/* Only allow one event clock source */
1168 	if (IS_ENABLED(CONFIG_HTE) &&
1169 	    (flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME) &&
1170 	    (flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE))
1171 		return -EINVAL;
1172 
1173 	/* Edge detection requires explicit input. */
1174 	if ((flags & GPIO_V2_LINE_EDGE_FLAGS) &&
1175 	    !(flags & GPIO_V2_LINE_FLAG_INPUT))
1176 		return -EINVAL;
1177 
1178 	/*
1179 	 * Do not allow OPEN_SOURCE and OPEN_DRAIN flags in a single
1180 	 * request. If the hardware actually supports enabling both at the
1181 	 * same time the electrical result would be disastrous.
1182 	 */
1183 	if ((flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN) &&
1184 	    (flags & GPIO_V2_LINE_FLAG_OPEN_SOURCE))
1185 		return -EINVAL;
1186 
1187 	/* Drive requires explicit output direction. */
1188 	if ((flags & GPIO_V2_LINE_DRIVE_FLAGS) &&
1189 	    !(flags & GPIO_V2_LINE_FLAG_OUTPUT))
1190 		return -EINVAL;
1191 
1192 	/* Bias requires explicit direction. */
1193 	if ((flags & GPIO_V2_LINE_BIAS_FLAGS) &&
1194 	    !(flags & GPIO_V2_LINE_DIRECTION_FLAGS))
1195 		return -EINVAL;
1196 
1197 	/* Only one bias flag can be set. */
1198 	if (((flags & GPIO_V2_LINE_FLAG_BIAS_DISABLED) &&
1199 	     (flags & (GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN |
1200 		       GPIO_V2_LINE_FLAG_BIAS_PULL_UP))) ||
1201 	    ((flags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN) &&
1202 	     (flags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP)))
1203 		return -EINVAL;
1204 
1205 	return 0;
1206 }
1207 
gpio_v2_line_config_validate(struct gpio_v2_line_config * lc,unsigned int num_lines)1208 static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
1209 					unsigned int num_lines)
1210 {
1211 	unsigned int i;
1212 	u64 flags;
1213 	int ret;
1214 
1215 	if (lc->num_attrs > GPIO_V2_LINE_NUM_ATTRS_MAX)
1216 		return -EINVAL;
1217 
1218 	if (!mem_is_zero(lc->padding, sizeof(lc->padding)))
1219 		return -EINVAL;
1220 
1221 	for (i = 0; i < num_lines; i++) {
1222 		flags = gpio_v2_line_config_flags(lc, i);
1223 		ret = gpio_v2_line_flags_validate(flags);
1224 		if (ret)
1225 			return ret;
1226 
1227 		/* debounce requires explicit input */
1228 		if (gpio_v2_line_config_debounced(lc, i) &&
1229 		    !(flags & GPIO_V2_LINE_FLAG_INPUT))
1230 			return -EINVAL;
1231 	}
1232 	return 0;
1233 }
1234 
gpio_v2_line_config_flags_to_desc_flags(u64 lflags,unsigned long * flagsp)1235 static void gpio_v2_line_config_flags_to_desc_flags(u64 lflags,
1236 						    unsigned long *flagsp)
1237 {
1238 	unsigned long flags = READ_ONCE(*flagsp);
1239 
1240 	assign_bit(FLAG_ACTIVE_LOW, &flags,
1241 		   lflags & GPIO_V2_LINE_FLAG_ACTIVE_LOW);
1242 
1243 	if (lflags & GPIO_V2_LINE_FLAG_OUTPUT)
1244 		set_bit(FLAG_IS_OUT, &flags);
1245 	else if (lflags & GPIO_V2_LINE_FLAG_INPUT)
1246 		clear_bit(FLAG_IS_OUT, &flags);
1247 
1248 	assign_bit(FLAG_EDGE_RISING, &flags,
1249 		   lflags & GPIO_V2_LINE_FLAG_EDGE_RISING);
1250 	assign_bit(FLAG_EDGE_FALLING, &flags,
1251 		   lflags & GPIO_V2_LINE_FLAG_EDGE_FALLING);
1252 
1253 	assign_bit(FLAG_OPEN_DRAIN, &flags,
1254 		   lflags & GPIO_V2_LINE_FLAG_OPEN_DRAIN);
1255 	assign_bit(FLAG_OPEN_SOURCE, &flags,
1256 		   lflags & GPIO_V2_LINE_FLAG_OPEN_SOURCE);
1257 
1258 	assign_bit(FLAG_PULL_UP, &flags,
1259 		   lflags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP);
1260 	assign_bit(FLAG_PULL_DOWN, &flags,
1261 		   lflags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN);
1262 	assign_bit(FLAG_BIAS_DISABLE, &flags,
1263 		   lflags & GPIO_V2_LINE_FLAG_BIAS_DISABLED);
1264 
1265 	assign_bit(FLAG_EVENT_CLOCK_REALTIME, &flags,
1266 		   lflags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME);
1267 	assign_bit(FLAG_EVENT_CLOCK_HTE, &flags,
1268 		   lflags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE);
1269 
1270 	WRITE_ONCE(*flagsp, flags);
1271 }
1272 
linereq_get_values(struct linereq * lr,void __user * ip)1273 static long linereq_get_values(struct linereq *lr, void __user *ip)
1274 {
1275 	struct gpio_v2_line_values lv;
1276 	DECLARE_BITMAP(vals, GPIO_V2_LINES_MAX);
1277 	struct gpio_desc **descs;
1278 	unsigned int i, didx, num_get;
1279 	bool val;
1280 	int ret;
1281 
1282 	/* NOTE: It's ok to read values of output lines. */
1283 	if (copy_from_user(&lv, ip, sizeof(lv)))
1284 		return -EFAULT;
1285 
1286 	/*
1287 	 * gpiod_get_array_value_complex() requires compacted desc and val
1288 	 * arrays, rather than the sparse ones in lv.
1289 	 * Calculation of num_get and construction of the desc array is
1290 	 * optimized to avoid allocation for the desc array for the common
1291 	 * num_get == 1 case.
1292 	 */
1293 	/* scan requested lines to calculate the subset to get */
1294 	for (num_get = 0, i = 0; i < lr->num_lines; i++) {
1295 		if (lv.mask & BIT_ULL(i)) {
1296 			num_get++;
1297 			/* capture desc for the num_get == 1 case */
1298 			descs = &lr->lines[i].desc;
1299 		}
1300 	}
1301 
1302 	if (num_get == 0)
1303 		return -EINVAL;
1304 
1305 	if (num_get != 1) {
1306 		/* build compacted desc array */
1307 		descs = kmalloc_array(num_get, sizeof(*descs), GFP_KERNEL);
1308 		if (!descs)
1309 			return -ENOMEM;
1310 		for (didx = 0, i = 0; i < lr->num_lines; i++) {
1311 			if (lv.mask & BIT_ULL(i)) {
1312 				descs[didx] = lr->lines[i].desc;
1313 				didx++;
1314 			}
1315 		}
1316 	}
1317 	ret = gpiod_get_array_value_complex(false, true, num_get,
1318 					    descs, NULL, vals);
1319 
1320 	if (num_get != 1)
1321 		kfree(descs);
1322 	if (ret)
1323 		return ret;
1324 
1325 	lv.bits = 0;
1326 	for (didx = 0, i = 0; i < lr->num_lines; i++) {
1327 		/* unpack compacted vals for the response */
1328 		if (lv.mask & BIT_ULL(i)) {
1329 			if (lr->lines[i].sw_debounced)
1330 				val = debounced_value(&lr->lines[i]);
1331 			else
1332 				val = test_bit(didx, vals);
1333 			if (val)
1334 				lv.bits |= BIT_ULL(i);
1335 			didx++;
1336 		}
1337 	}
1338 
1339 	if (copy_to_user(ip, &lv, sizeof(lv)))
1340 		return -EFAULT;
1341 
1342 	return 0;
1343 }
1344 
linereq_set_values(struct linereq * lr,void __user * ip)1345 static long linereq_set_values(struct linereq *lr, void __user *ip)
1346 {
1347 	DECLARE_BITMAP(vals, GPIO_V2_LINES_MAX);
1348 	struct gpio_v2_line_values lv;
1349 	struct gpio_desc **descs;
1350 	unsigned int i, didx, num_set;
1351 	int ret;
1352 
1353 	if (copy_from_user(&lv, ip, sizeof(lv)))
1354 		return -EFAULT;
1355 
1356 	guard(mutex)(&lr->config_mutex);
1357 
1358 	/*
1359 	 * gpiod_set_array_value_complex() requires compacted desc and val
1360 	 * arrays, rather than the sparse ones in lv.
1361 	 * Calculation of num_set and construction of the descs and vals arrays
1362 	 * is optimized to minimize scanning the lv->mask, and to avoid
1363 	 * allocation for the desc array for the common num_set == 1 case.
1364 	 */
1365 	bitmap_zero(vals, GPIO_V2_LINES_MAX);
1366 	/* scan requested lines to determine the subset to be set */
1367 	for (num_set = 0, i = 0; i < lr->num_lines; i++) {
1368 		if (lv.mask & BIT_ULL(i)) {
1369 			/* setting inputs is not allowed */
1370 			if (!test_bit(FLAG_IS_OUT, &lr->lines[i].desc->flags))
1371 				return -EPERM;
1372 			/* add to compacted values */
1373 			if (lv.bits & BIT_ULL(i))
1374 				__set_bit(num_set, vals);
1375 			num_set++;
1376 			/* capture desc for the num_set == 1 case */
1377 			descs = &lr->lines[i].desc;
1378 		}
1379 	}
1380 	if (num_set == 0)
1381 		return -EINVAL;
1382 
1383 	if (num_set != 1) {
1384 		/* build compacted desc array */
1385 		descs = kmalloc_array(num_set, sizeof(*descs), GFP_KERNEL);
1386 		if (!descs)
1387 			return -ENOMEM;
1388 		for (didx = 0, i = 0; i < lr->num_lines; i++) {
1389 			if (lv.mask & BIT_ULL(i)) {
1390 				descs[didx] = lr->lines[i].desc;
1391 				didx++;
1392 			}
1393 		}
1394 	}
1395 	ret = gpiod_set_array_value_complex(false, true, num_set,
1396 					    descs, NULL, vals);
1397 
1398 	if (num_set != 1)
1399 		kfree(descs);
1400 	return ret;
1401 }
1402 
linereq_set_config(struct linereq * lr,void __user * ip)1403 static long linereq_set_config(struct linereq *lr, void __user *ip)
1404 {
1405 	struct gpio_v2_line_config lc;
1406 	struct gpio_desc *desc;
1407 	struct line *line;
1408 	unsigned int i;
1409 	u64 flags, edflags;
1410 	int ret;
1411 
1412 	if (copy_from_user(&lc, ip, sizeof(lc)))
1413 		return -EFAULT;
1414 
1415 	ret = gpio_v2_line_config_validate(&lc, lr->num_lines);
1416 	if (ret)
1417 		return ret;
1418 
1419 	guard(mutex)(&lr->config_mutex);
1420 
1421 	for (i = 0; i < lr->num_lines; i++) {
1422 		line = &lr->lines[i];
1423 		desc = lr->lines[i].desc;
1424 		flags = gpio_v2_line_config_flags(&lc, i);
1425 		/*
1426 		 * Lines not explicitly reconfigured as input or output
1427 		 * are left unchanged.
1428 		 */
1429 		if (!(flags & GPIO_V2_LINE_DIRECTION_FLAGS))
1430 			continue;
1431 		gpio_v2_line_config_flags_to_desc_flags(flags, &desc->flags);
1432 		edflags = flags & GPIO_V2_LINE_EDGE_DETECTOR_FLAGS;
1433 		if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {
1434 			int val = gpio_v2_line_config_output_value(&lc, i);
1435 
1436 			edge_detector_stop(line);
1437 			ret = gpiod_direction_output_nonotify(desc, val);
1438 			if (ret)
1439 				return ret;
1440 		} else {
1441 			ret = gpiod_direction_input_nonotify(desc);
1442 			if (ret)
1443 				return ret;
1444 
1445 			ret = edge_detector_update(line, &lc, i, edflags);
1446 			if (ret)
1447 				return ret;
1448 		}
1449 
1450 		WRITE_ONCE(line->edflags, edflags);
1451 
1452 		gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_CONFIG);
1453 	}
1454 	return 0;
1455 }
1456 
linereq_ioctl(struct file * file,unsigned int cmd,unsigned long arg)1457 static long linereq_ioctl(struct file *file, unsigned int cmd,
1458 			  unsigned long arg)
1459 {
1460 	struct linereq *lr = file->private_data;
1461 	void __user *ip = (void __user *)arg;
1462 
1463 	guard(srcu)(&lr->gdev->srcu);
1464 
1465 	if (!rcu_access_pointer(lr->gdev->chip))
1466 		return -ENODEV;
1467 
1468 	switch (cmd) {
1469 	case GPIO_V2_LINE_GET_VALUES_IOCTL:
1470 		return linereq_get_values(lr, ip);
1471 	case GPIO_V2_LINE_SET_VALUES_IOCTL:
1472 		return linereq_set_values(lr, ip);
1473 	case GPIO_V2_LINE_SET_CONFIG_IOCTL:
1474 		return linereq_set_config(lr, ip);
1475 	default:
1476 		return -EINVAL;
1477 	}
1478 }
1479 
1480 #ifdef CONFIG_COMPAT
linereq_ioctl_compat(struct file * file,unsigned int cmd,unsigned long arg)1481 static long linereq_ioctl_compat(struct file *file, unsigned int cmd,
1482 				 unsigned long arg)
1483 {
1484 	return linereq_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
1485 }
1486 #endif
1487 
linereq_poll(struct file * file,struct poll_table_struct * wait)1488 static __poll_t linereq_poll(struct file *file,
1489 			     struct poll_table_struct *wait)
1490 {
1491 	struct linereq *lr = file->private_data;
1492 	__poll_t events = 0;
1493 
1494 	guard(srcu)(&lr->gdev->srcu);
1495 
1496 	if (!rcu_access_pointer(lr->gdev->chip))
1497 		return EPOLLHUP | EPOLLERR;
1498 
1499 	poll_wait(file, &lr->wait, wait);
1500 
1501 	if (!kfifo_is_empty_spinlocked_noirqsave(&lr->events,
1502 						 &lr->wait.lock))
1503 		events = EPOLLIN | EPOLLRDNORM;
1504 
1505 	return events;
1506 }
1507 
linereq_read(struct file * file,char __user * buf,size_t count,loff_t * f_ps)1508 static ssize_t linereq_read(struct file *file, char __user *buf,
1509 			    size_t count, loff_t *f_ps)
1510 {
1511 	struct linereq *lr = file->private_data;
1512 	struct gpio_v2_line_event le;
1513 	ssize_t bytes_read = 0;
1514 	int ret;
1515 
1516 	guard(srcu)(&lr->gdev->srcu);
1517 
1518 	if (!rcu_access_pointer(lr->gdev->chip))
1519 		return -ENODEV;
1520 
1521 	if (count < sizeof(le))
1522 		return -EINVAL;
1523 
1524 	do {
1525 		scoped_guard(spinlock, &lr->wait.lock) {
1526 			if (kfifo_is_empty(&lr->events)) {
1527 				if (bytes_read)
1528 					return bytes_read;
1529 
1530 				if (file->f_flags & O_NONBLOCK)
1531 					return -EAGAIN;
1532 
1533 				ret = wait_event_interruptible_locked(lr->wait,
1534 						!kfifo_is_empty(&lr->events));
1535 				if (ret)
1536 					return ret;
1537 			}
1538 
1539 			if (kfifo_out(&lr->events, &le, 1) != 1) {
1540 				/*
1541 				 * This should never happen - we hold the
1542 				 * lock from the moment we learned the fifo
1543 				 * is no longer empty until now.
1544 				 */
1545 				WARN(1, "failed to read from non-empty kfifo");
1546 				return -EIO;
1547 			}
1548 		}
1549 
1550 		if (copy_to_user(buf + bytes_read, &le, sizeof(le)))
1551 			return -EFAULT;
1552 		bytes_read += sizeof(le);
1553 	} while (count >= bytes_read + sizeof(le));
1554 
1555 	return bytes_read;
1556 }
1557 
linereq_free(struct linereq * lr)1558 static void linereq_free(struct linereq *lr)
1559 {
1560 	unsigned int i;
1561 
1562 	if (lr->device_unregistered_nb.notifier_call)
1563 		blocking_notifier_chain_unregister(&lr->gdev->device_notifier,
1564 						   &lr->device_unregistered_nb);
1565 
1566 	for (i = 0; i < lr->num_lines; i++) {
1567 		if (lr->lines[i].desc) {
1568 			edge_detector_stop(&lr->lines[i]);
1569 			gpiod_free(lr->lines[i].desc);
1570 		}
1571 	}
1572 	kfifo_free(&lr->events);
1573 	kfree(lr->label);
1574 	gpio_device_put(lr->gdev);
1575 	kvfree(lr);
1576 }
1577 
linereq_release(struct inode * inode,struct file * file)1578 static int linereq_release(struct inode *inode, struct file *file)
1579 {
1580 	struct linereq *lr = file->private_data;
1581 
1582 	linereq_free(lr);
1583 	return 0;
1584 }
1585 
1586 #ifdef CONFIG_PROC_FS
linereq_show_fdinfo(struct seq_file * out,struct file * file)1587 static void linereq_show_fdinfo(struct seq_file *out, struct file *file)
1588 {
1589 	struct linereq *lr = file->private_data;
1590 	struct device *dev = &lr->gdev->dev;
1591 	u16 i;
1592 
1593 	seq_printf(out, "gpio-chip:\t%s\n", dev_name(dev));
1594 
1595 	for (i = 0; i < lr->num_lines; i++)
1596 		seq_printf(out, "gpio-line:\t%d\n",
1597 			   gpio_chip_hwgpio(lr->lines[i].desc));
1598 }
1599 #endif
1600 
1601 static const struct file_operations line_fileops = {
1602 	.release = linereq_release,
1603 	.read = linereq_read,
1604 	.poll = linereq_poll,
1605 	.owner = THIS_MODULE,
1606 	.llseek = noop_llseek,
1607 	.unlocked_ioctl = linereq_ioctl,
1608 #ifdef CONFIG_COMPAT
1609 	.compat_ioctl = linereq_ioctl_compat,
1610 #endif
1611 #ifdef CONFIG_PROC_FS
1612 	.show_fdinfo = linereq_show_fdinfo,
1613 #endif
1614 };
1615 
linereq_create(struct gpio_device * gdev,void __user * ip)1616 static int linereq_create(struct gpio_device *gdev, void __user *ip)
1617 {
1618 	struct gpio_v2_line_request ulr;
1619 	struct gpio_v2_line_config *lc;
1620 	struct linereq *lr;
1621 	struct file *file;
1622 	u64 flags, edflags;
1623 	unsigned int i;
1624 	int fd, ret;
1625 
1626 	if (copy_from_user(&ulr, ip, sizeof(ulr)))
1627 		return -EFAULT;
1628 
1629 	if ((ulr.num_lines == 0) || (ulr.num_lines > GPIO_V2_LINES_MAX))
1630 		return -EINVAL;
1631 
1632 	if (!mem_is_zero(ulr.padding, sizeof(ulr.padding)))
1633 		return -EINVAL;
1634 
1635 	lc = &ulr.config;
1636 	ret = gpio_v2_line_config_validate(lc, ulr.num_lines);
1637 	if (ret)
1638 		return ret;
1639 
1640 	lr = kvzalloc(struct_size(lr, lines, ulr.num_lines), GFP_KERNEL);
1641 	if (!lr)
1642 		return -ENOMEM;
1643 	lr->num_lines = ulr.num_lines;
1644 
1645 	lr->gdev = gpio_device_get(gdev);
1646 
1647 	for (i = 0; i < ulr.num_lines; i++) {
1648 		lr->lines[i].req = lr;
1649 		WRITE_ONCE(lr->lines[i].sw_debounced, 0);
1650 		INIT_DELAYED_WORK(&lr->lines[i].work, debounce_work_func);
1651 	}
1652 
1653 	if (ulr.consumer[0] != '\0') {
1654 		/* label is only initialized if consumer is set */
1655 		lr->label = kstrndup(ulr.consumer, sizeof(ulr.consumer) - 1,
1656 				     GFP_KERNEL);
1657 		if (!lr->label) {
1658 			ret = -ENOMEM;
1659 			goto out_free_linereq;
1660 		}
1661 	}
1662 
1663 	mutex_init(&lr->config_mutex);
1664 	init_waitqueue_head(&lr->wait);
1665 	INIT_KFIFO(lr->events);
1666 	lr->event_buffer_size = ulr.event_buffer_size;
1667 	if (lr->event_buffer_size == 0)
1668 		lr->event_buffer_size = ulr.num_lines * 16;
1669 	else if (lr->event_buffer_size > GPIO_V2_LINES_MAX * 16)
1670 		lr->event_buffer_size = GPIO_V2_LINES_MAX * 16;
1671 
1672 	atomic_set(&lr->seqno, 0);
1673 
1674 	/* Request each GPIO */
1675 	for (i = 0; i < ulr.num_lines; i++) {
1676 		u32 offset = ulr.offsets[i];
1677 		struct gpio_desc *desc = gpio_device_get_desc(gdev, offset);
1678 
1679 		if (IS_ERR(desc)) {
1680 			ret = PTR_ERR(desc);
1681 			goto out_free_linereq;
1682 		}
1683 
1684 		ret = gpiod_request_user(desc, lr->label);
1685 		if (ret)
1686 			goto out_free_linereq;
1687 
1688 		lr->lines[i].desc = desc;
1689 		flags = gpio_v2_line_config_flags(lc, i);
1690 		gpio_v2_line_config_flags_to_desc_flags(flags, &desc->flags);
1691 
1692 		ret = gpiod_set_transitory(desc, false);
1693 		if (ret < 0)
1694 			goto out_free_linereq;
1695 
1696 		edflags = flags & GPIO_V2_LINE_EDGE_DETECTOR_FLAGS;
1697 		/*
1698 		 * Lines have to be requested explicitly for input
1699 		 * or output, else the line will be treated "as is".
1700 		 */
1701 		if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {
1702 			int val = gpio_v2_line_config_output_value(lc, i);
1703 
1704 			ret = gpiod_direction_output_nonotify(desc, val);
1705 			if (ret)
1706 				goto out_free_linereq;
1707 		} else if (flags & GPIO_V2_LINE_FLAG_INPUT) {
1708 			ret = gpiod_direction_input_nonotify(desc);
1709 			if (ret)
1710 				goto out_free_linereq;
1711 
1712 			ret = edge_detector_setup(&lr->lines[i], lc, i,
1713 						  edflags);
1714 			if (ret)
1715 				goto out_free_linereq;
1716 		}
1717 
1718 		lr->lines[i].edflags = edflags;
1719 
1720 		gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_REQUESTED);
1721 
1722 		dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
1723 			offset);
1724 	}
1725 
1726 	lr->device_unregistered_nb.notifier_call = linereq_unregistered_notify;
1727 	ret = blocking_notifier_chain_register(&gdev->device_notifier,
1728 					       &lr->device_unregistered_nb);
1729 	if (ret)
1730 		goto out_free_linereq;
1731 
1732 	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
1733 	if (fd < 0) {
1734 		ret = fd;
1735 		goto out_free_linereq;
1736 	}
1737 
1738 	file = anon_inode_getfile("gpio-line", &line_fileops, lr,
1739 				  O_RDONLY | O_CLOEXEC);
1740 	if (IS_ERR(file)) {
1741 		ret = PTR_ERR(file);
1742 		goto out_put_unused_fd;
1743 	}
1744 
1745 	ulr.fd = fd;
1746 	if (copy_to_user(ip, &ulr, sizeof(ulr))) {
1747 		/*
1748 		 * fput() will trigger the release() callback, so do not go onto
1749 		 * the regular error cleanup path here.
1750 		 */
1751 		fput(file);
1752 		put_unused_fd(fd);
1753 		return -EFAULT;
1754 	}
1755 
1756 	fd_install(fd, file);
1757 
1758 	dev_dbg(&gdev->dev, "registered chardev handle for %d lines\n",
1759 		lr->num_lines);
1760 
1761 	return 0;
1762 
1763 out_put_unused_fd:
1764 	put_unused_fd(fd);
1765 out_free_linereq:
1766 	linereq_free(lr);
1767 	return ret;
1768 }
1769 
1770 #ifdef CONFIG_GPIO_CDEV_V1
1771 
1772 /*
1773  * GPIO line event management
1774  */
1775 
1776 /**
1777  * struct lineevent_state - contains the state of a userspace event
1778  * @gdev: the GPIO device the event pertains to
1779  * @label: consumer label used to tag descriptors
1780  * @desc: the GPIO descriptor held by this event
1781  * @eflags: the event flags this line was requested with
1782  * @irq: the interrupt that trigger in response to events on this GPIO
1783  * @wait: wait queue that handles blocking reads of events
1784  * @device_unregistered_nb: notifier block for receiving gdev unregister events
1785  * @events: KFIFO for the GPIO events
1786  * @timestamp: cache for the timestamp storing it between hardirq
1787  * and IRQ thread, used to bring the timestamp close to the actual
1788  * event
1789  */
1790 struct lineevent_state {
1791 	struct gpio_device *gdev;
1792 	const char *label;
1793 	struct gpio_desc *desc;
1794 	u32 eflags;
1795 	int irq;
1796 	wait_queue_head_t wait;
1797 	struct notifier_block device_unregistered_nb;
1798 	DECLARE_KFIFO(events, struct gpioevent_data, 16);
1799 	u64 timestamp;
1800 };
1801 
1802 #define GPIOEVENT_REQUEST_VALID_FLAGS \
1803 	(GPIOEVENT_REQUEST_RISING_EDGE | \
1804 	GPIOEVENT_REQUEST_FALLING_EDGE)
1805 
lineevent_poll(struct file * file,struct poll_table_struct * wait)1806 static __poll_t lineevent_poll(struct file *file,
1807 			       struct poll_table_struct *wait)
1808 {
1809 	struct lineevent_state *le = file->private_data;
1810 	__poll_t events = 0;
1811 
1812 	guard(srcu)(&le->gdev->srcu);
1813 
1814 	if (!rcu_access_pointer(le->gdev->chip))
1815 		return EPOLLHUP | EPOLLERR;
1816 
1817 	poll_wait(file, &le->wait, wait);
1818 
1819 	if (!kfifo_is_empty_spinlocked_noirqsave(&le->events, &le->wait.lock))
1820 		events = EPOLLIN | EPOLLRDNORM;
1821 
1822 	return events;
1823 }
1824 
lineevent_unregistered_notify(struct notifier_block * nb,unsigned long action,void * data)1825 static int lineevent_unregistered_notify(struct notifier_block *nb,
1826 					 unsigned long action, void *data)
1827 {
1828 	struct lineevent_state *le = container_of(nb, struct lineevent_state,
1829 						  device_unregistered_nb);
1830 
1831 	wake_up_poll(&le->wait, EPOLLIN | EPOLLERR);
1832 
1833 	return NOTIFY_OK;
1834 }
1835 
1836 struct compat_gpioeevent_data {
1837 	compat_u64	timestamp;
1838 	u32		id;
1839 };
1840 
lineevent_read(struct file * file,char __user * buf,size_t count,loff_t * f_ps)1841 static ssize_t lineevent_read(struct file *file, char __user *buf,
1842 			      size_t count, loff_t *f_ps)
1843 {
1844 	struct lineevent_state *le = file->private_data;
1845 	struct gpioevent_data ge;
1846 	ssize_t bytes_read = 0;
1847 	ssize_t ge_size;
1848 	int ret;
1849 
1850 	guard(srcu)(&le->gdev->srcu);
1851 
1852 	if (!rcu_access_pointer(le->gdev->chip))
1853 		return -ENODEV;
1854 
1855 	/*
1856 	 * When compatible system call is being used the struct gpioevent_data,
1857 	 * in case of at least ia32, has different size due to the alignment
1858 	 * differences. Because we have first member 64 bits followed by one of
1859 	 * 32 bits there is no gap between them. The only difference is the
1860 	 * padding at the end of the data structure. Hence, we calculate the
1861 	 * actual sizeof() and pass this as an argument to copy_to_user() to
1862 	 * drop unneeded bytes from the output.
1863 	 */
1864 	if (compat_need_64bit_alignment_fixup())
1865 		ge_size = sizeof(struct compat_gpioeevent_data);
1866 	else
1867 		ge_size = sizeof(struct gpioevent_data);
1868 	if (count < ge_size)
1869 		return -EINVAL;
1870 
1871 	do {
1872 		scoped_guard(spinlock, &le->wait.lock) {
1873 			if (kfifo_is_empty(&le->events)) {
1874 				if (bytes_read)
1875 					return bytes_read;
1876 
1877 				if (file->f_flags & O_NONBLOCK)
1878 					return -EAGAIN;
1879 
1880 				ret = wait_event_interruptible_locked(le->wait,
1881 						!kfifo_is_empty(&le->events));
1882 				if (ret)
1883 					return ret;
1884 			}
1885 
1886 			if (kfifo_out(&le->events, &ge, 1) != 1) {
1887 				/*
1888 				 * This should never happen - we hold the
1889 				 * lock from the moment we learned the fifo
1890 				 * is no longer empty until now.
1891 				 */
1892 				WARN(1, "failed to read from non-empty kfifo");
1893 				return -EIO;
1894 			}
1895 		}
1896 
1897 		if (copy_to_user(buf + bytes_read, &ge, ge_size))
1898 			return -EFAULT;
1899 		bytes_read += ge_size;
1900 	} while (count >= bytes_read + ge_size);
1901 
1902 	return bytes_read;
1903 }
1904 
lineevent_free(struct lineevent_state * le)1905 static void lineevent_free(struct lineevent_state *le)
1906 {
1907 	if (le->device_unregistered_nb.notifier_call)
1908 		blocking_notifier_chain_unregister(&le->gdev->device_notifier,
1909 						   &le->device_unregistered_nb);
1910 	if (le->irq)
1911 		free_irq_label(free_irq(le->irq, le));
1912 	if (le->desc)
1913 		gpiod_free(le->desc);
1914 	kfree(le->label);
1915 	gpio_device_put(le->gdev);
1916 	kfree(le);
1917 }
1918 
lineevent_release(struct inode * inode,struct file * file)1919 static int lineevent_release(struct inode *inode, struct file *file)
1920 {
1921 	lineevent_free(file->private_data);
1922 	return 0;
1923 }
1924 
lineevent_ioctl(struct file * file,unsigned int cmd,unsigned long arg)1925 static long lineevent_ioctl(struct file *file, unsigned int cmd,
1926 			    unsigned long arg)
1927 {
1928 	struct lineevent_state *le = file->private_data;
1929 	void __user *ip = (void __user *)arg;
1930 	struct gpiohandle_data ghd;
1931 
1932 	guard(srcu)(&le->gdev->srcu);
1933 
1934 	if (!rcu_access_pointer(le->gdev->chip))
1935 		return -ENODEV;
1936 
1937 	/*
1938 	 * We can get the value for an event line but not set it,
1939 	 * because it is input by definition.
1940 	 */
1941 	if (cmd == GPIOHANDLE_GET_LINE_VALUES_IOCTL) {
1942 		int val;
1943 
1944 		memset(&ghd, 0, sizeof(ghd));
1945 
1946 		val = gpiod_get_value_cansleep(le->desc);
1947 		if (val < 0)
1948 			return val;
1949 		ghd.values[0] = val;
1950 
1951 		if (copy_to_user(ip, &ghd, sizeof(ghd)))
1952 			return -EFAULT;
1953 
1954 		return 0;
1955 	}
1956 	return -EINVAL;
1957 }
1958 
1959 #ifdef CONFIG_COMPAT
lineevent_ioctl_compat(struct file * file,unsigned int cmd,unsigned long arg)1960 static long lineevent_ioctl_compat(struct file *file, unsigned int cmd,
1961 				   unsigned long arg)
1962 {
1963 	return lineevent_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
1964 }
1965 #endif
1966 
1967 static const struct file_operations lineevent_fileops = {
1968 	.release = lineevent_release,
1969 	.read = lineevent_read,
1970 	.poll = lineevent_poll,
1971 	.owner = THIS_MODULE,
1972 	.llseek = noop_llseek,
1973 	.unlocked_ioctl = lineevent_ioctl,
1974 #ifdef CONFIG_COMPAT
1975 	.compat_ioctl = lineevent_ioctl_compat,
1976 #endif
1977 };
1978 
lineevent_irq_thread(int irq,void * p)1979 static irqreturn_t lineevent_irq_thread(int irq, void *p)
1980 {
1981 	struct lineevent_state *le = p;
1982 	struct gpioevent_data ge;
1983 	int ret;
1984 
1985 	/* Do not leak kernel stack to userspace */
1986 	memset(&ge, 0, sizeof(ge));
1987 
1988 	/*
1989 	 * We may be running from a nested threaded interrupt in which case
1990 	 * we didn't get the timestamp from lineevent_irq_handler().
1991 	 */
1992 	if (!le->timestamp)
1993 		ge.timestamp = ktime_get_ns();
1994 	else
1995 		ge.timestamp = le->timestamp;
1996 
1997 	if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE
1998 	    && le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
1999 		int level = gpiod_get_value_cansleep(le->desc);
2000 
2001 		if (level)
2002 			/* Emit low-to-high event */
2003 			ge.id = GPIOEVENT_EVENT_RISING_EDGE;
2004 		else
2005 			/* Emit high-to-low event */
2006 			ge.id = GPIOEVENT_EVENT_FALLING_EDGE;
2007 	} else if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE) {
2008 		/* Emit low-to-high event */
2009 		ge.id = GPIOEVENT_EVENT_RISING_EDGE;
2010 	} else if (le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
2011 		/* Emit high-to-low event */
2012 		ge.id = GPIOEVENT_EVENT_FALLING_EDGE;
2013 	} else {
2014 		return IRQ_NONE;
2015 	}
2016 
2017 	ret = kfifo_in_spinlocked_noirqsave(&le->events, &ge,
2018 					    1, &le->wait.lock);
2019 	if (ret)
2020 		wake_up_poll(&le->wait, EPOLLIN);
2021 	else
2022 		pr_debug_ratelimited("event FIFO is full - event dropped\n");
2023 
2024 	return IRQ_HANDLED;
2025 }
2026 
lineevent_irq_handler(int irq,void * p)2027 static irqreturn_t lineevent_irq_handler(int irq, void *p)
2028 {
2029 	struct lineevent_state *le = p;
2030 
2031 	/*
2032 	 * Just store the timestamp in hardirq context so we get it as
2033 	 * close in time as possible to the actual event.
2034 	 */
2035 	le->timestamp = ktime_get_ns();
2036 
2037 	return IRQ_WAKE_THREAD;
2038 }
2039 
lineevent_create(struct gpio_device * gdev,void __user * ip)2040 static int lineevent_create(struct gpio_device *gdev, void __user *ip)
2041 {
2042 	struct gpioevent_request eventreq;
2043 	struct lineevent_state *le;
2044 	struct gpio_desc *desc;
2045 	struct file *file;
2046 	u32 offset;
2047 	u32 lflags;
2048 	u32 eflags;
2049 	int fd;
2050 	int ret;
2051 	int irq, irqflags = 0;
2052 	char *label;
2053 
2054 	if (copy_from_user(&eventreq, ip, sizeof(eventreq)))
2055 		return -EFAULT;
2056 
2057 	offset = eventreq.lineoffset;
2058 	lflags = eventreq.handleflags;
2059 	eflags = eventreq.eventflags;
2060 
2061 	desc = gpio_device_get_desc(gdev, offset);
2062 	if (IS_ERR(desc))
2063 		return PTR_ERR(desc);
2064 
2065 	/* Return an error if a unknown flag is set */
2066 	if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
2067 	    (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS))
2068 		return -EINVAL;
2069 
2070 	/* This is just wrong: we don't look for events on output lines */
2071 	if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) ||
2072 	    (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
2073 	    (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
2074 		return -EINVAL;
2075 
2076 	/* Only one bias flag can be set. */
2077 	if (((lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE) &&
2078 	     (lflags & (GPIOHANDLE_REQUEST_BIAS_PULL_DOWN |
2079 			GPIOHANDLE_REQUEST_BIAS_PULL_UP))) ||
2080 	    ((lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN) &&
2081 	     (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP)))
2082 		return -EINVAL;
2083 
2084 	le = kzalloc(sizeof(*le), GFP_KERNEL);
2085 	if (!le)
2086 		return -ENOMEM;
2087 	le->gdev = gpio_device_get(gdev);
2088 
2089 	if (eventreq.consumer_label[0] != '\0') {
2090 		/* label is only initialized if consumer_label is set */
2091 		le->label = kstrndup(eventreq.consumer_label,
2092 				     sizeof(eventreq.consumer_label) - 1,
2093 				     GFP_KERNEL);
2094 		if (!le->label) {
2095 			ret = -ENOMEM;
2096 			goto out_free_le;
2097 		}
2098 	}
2099 
2100 	ret = gpiod_request_user(desc, le->label);
2101 	if (ret)
2102 		goto out_free_le;
2103 	le->desc = desc;
2104 	le->eflags = eflags;
2105 
2106 	linehandle_flags_to_desc_flags(lflags, &desc->flags);
2107 
2108 	ret = gpiod_direction_input(desc);
2109 	if (ret)
2110 		goto out_free_le;
2111 
2112 	gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_REQUESTED);
2113 
2114 	irq = gpiod_to_irq(desc);
2115 	if (irq <= 0) {
2116 		ret = -ENODEV;
2117 		goto out_free_le;
2118 	}
2119 
2120 	if (eflags & GPIOEVENT_REQUEST_RISING_EDGE)
2121 		irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
2122 			IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
2123 	if (eflags & GPIOEVENT_REQUEST_FALLING_EDGE)
2124 		irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
2125 			IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
2126 	irqflags |= IRQF_ONESHOT;
2127 
2128 	INIT_KFIFO(le->events);
2129 	init_waitqueue_head(&le->wait);
2130 
2131 	le->device_unregistered_nb.notifier_call = lineevent_unregistered_notify;
2132 	ret = blocking_notifier_chain_register(&gdev->device_notifier,
2133 					       &le->device_unregistered_nb);
2134 	if (ret)
2135 		goto out_free_le;
2136 
2137 	label = make_irq_label(le->label);
2138 	if (IS_ERR(label)) {
2139 		ret = PTR_ERR(label);
2140 		goto out_free_le;
2141 	}
2142 
2143 	/* Request a thread to read the events */
2144 	ret = request_threaded_irq(irq,
2145 				   lineevent_irq_handler,
2146 				   lineevent_irq_thread,
2147 				   irqflags,
2148 				   label,
2149 				   le);
2150 	if (ret) {
2151 		free_irq_label(label);
2152 		goto out_free_le;
2153 	}
2154 
2155 	le->irq = irq;
2156 
2157 	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
2158 	if (fd < 0) {
2159 		ret = fd;
2160 		goto out_free_le;
2161 	}
2162 
2163 	file = anon_inode_getfile("gpio-event",
2164 				  &lineevent_fileops,
2165 				  le,
2166 				  O_RDONLY | O_CLOEXEC);
2167 	if (IS_ERR(file)) {
2168 		ret = PTR_ERR(file);
2169 		goto out_put_unused_fd;
2170 	}
2171 
2172 	eventreq.fd = fd;
2173 	if (copy_to_user(ip, &eventreq, sizeof(eventreq))) {
2174 		/*
2175 		 * fput() will trigger the release() callback, so do not go onto
2176 		 * the regular error cleanup path here.
2177 		 */
2178 		fput(file);
2179 		put_unused_fd(fd);
2180 		return -EFAULT;
2181 	}
2182 
2183 	fd_install(fd, file);
2184 
2185 	return 0;
2186 
2187 out_put_unused_fd:
2188 	put_unused_fd(fd);
2189 out_free_le:
2190 	lineevent_free(le);
2191 	return ret;
2192 }
2193 
gpio_v2_line_info_to_v1(struct gpio_v2_line_info * info_v2,struct gpioline_info * info_v1)2194 static void gpio_v2_line_info_to_v1(struct gpio_v2_line_info *info_v2,
2195 				    struct gpioline_info *info_v1)
2196 {
2197 	u64 flagsv2 = info_v2->flags;
2198 
2199 	memcpy(info_v1->name, info_v2->name, sizeof(info_v1->name));
2200 	memcpy(info_v1->consumer, info_v2->consumer, sizeof(info_v1->consumer));
2201 	info_v1->line_offset = info_v2->offset;
2202 	info_v1->flags = 0;
2203 
2204 	if (flagsv2 & GPIO_V2_LINE_FLAG_USED)
2205 		info_v1->flags |= GPIOLINE_FLAG_KERNEL;
2206 
2207 	if (flagsv2 & GPIO_V2_LINE_FLAG_OUTPUT)
2208 		info_v1->flags |= GPIOLINE_FLAG_IS_OUT;
2209 
2210 	if (flagsv2 & GPIO_V2_LINE_FLAG_ACTIVE_LOW)
2211 		info_v1->flags |= GPIOLINE_FLAG_ACTIVE_LOW;
2212 
2213 	if (flagsv2 & GPIO_V2_LINE_FLAG_OPEN_DRAIN)
2214 		info_v1->flags |= GPIOLINE_FLAG_OPEN_DRAIN;
2215 	if (flagsv2 & GPIO_V2_LINE_FLAG_OPEN_SOURCE)
2216 		info_v1->flags |= GPIOLINE_FLAG_OPEN_SOURCE;
2217 
2218 	if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_PULL_UP)
2219 		info_v1->flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
2220 	if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN)
2221 		info_v1->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
2222 	if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_DISABLED)
2223 		info_v1->flags |= GPIOLINE_FLAG_BIAS_DISABLE;
2224 }
2225 
gpio_v2_line_info_changed_to_v1(struct gpio_v2_line_info_changed * lic_v2,struct gpioline_info_changed * lic_v1)2226 static void gpio_v2_line_info_changed_to_v1(
2227 		struct gpio_v2_line_info_changed *lic_v2,
2228 		struct gpioline_info_changed *lic_v1)
2229 {
2230 	memset(lic_v1, 0, sizeof(*lic_v1));
2231 	gpio_v2_line_info_to_v1(&lic_v2->info, &lic_v1->info);
2232 	lic_v1->timestamp = lic_v2->timestamp_ns;
2233 	lic_v1->event_type = lic_v2->event_type;
2234 }
2235 
2236 #endif /* CONFIG_GPIO_CDEV_V1 */
2237 
gpio_desc_to_lineinfo(struct gpio_desc * desc,struct gpio_v2_line_info * info,bool atomic)2238 static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
2239 				  struct gpio_v2_line_info *info, bool atomic)
2240 {
2241 	u32 debounce_period_us;
2242 	unsigned long dflags;
2243 	const char *label;
2244 
2245 	CLASS(gpio_chip_guard, guard)(desc);
2246 	if (!guard.gc)
2247 		return;
2248 
2249 	memset(info, 0, sizeof(*info));
2250 	info->offset = gpio_chip_hwgpio(desc);
2251 
2252 	if (desc->name)
2253 		strscpy(info->name, desc->name, sizeof(info->name));
2254 
2255 	dflags = READ_ONCE(desc->flags);
2256 
2257 	scoped_guard(srcu, &desc->gdev->desc_srcu) {
2258 		label = gpiod_get_label(desc);
2259 		if (label && test_bit(FLAG_REQUESTED, &dflags))
2260 			strscpy(info->consumer, label,
2261 				sizeof(info->consumer));
2262 	}
2263 
2264 	/*
2265 	 * Userspace only need know that the kernel is using this GPIO so it
2266 	 * can't use it.
2267 	 * The calculation of the used flag is slightly racy, as it may read
2268 	 * desc, gc and pinctrl state without a lock covering all three at
2269 	 * once.  Worst case if the line is in transition and the calculation
2270 	 * is inconsistent then it looks to the user like they performed the
2271 	 * read on the other side of the transition - but that can always
2272 	 * happen.
2273 	 * The definitive test that a line is available to userspace is to
2274 	 * request it.
2275 	 */
2276 	if (test_bit(FLAG_REQUESTED, &dflags) ||
2277 	    test_bit(FLAG_IS_HOGGED, &dflags) ||
2278 	    test_bit(FLAG_EXPORT, &dflags) ||
2279 	    test_bit(FLAG_SYSFS, &dflags) ||
2280 	    !gpiochip_line_is_valid(guard.gc, info->offset)) {
2281 		info->flags |= GPIO_V2_LINE_FLAG_USED;
2282 	} else if (!atomic) {
2283 		if (!pinctrl_gpio_can_use_line(guard.gc, info->offset))
2284 			info->flags |= GPIO_V2_LINE_FLAG_USED;
2285 	}
2286 
2287 	if (test_bit(FLAG_IS_OUT, &dflags))
2288 		info->flags |= GPIO_V2_LINE_FLAG_OUTPUT;
2289 	else
2290 		info->flags |= GPIO_V2_LINE_FLAG_INPUT;
2291 
2292 	if (test_bit(FLAG_ACTIVE_LOW, &dflags))
2293 		info->flags |= GPIO_V2_LINE_FLAG_ACTIVE_LOW;
2294 
2295 	if (test_bit(FLAG_OPEN_DRAIN, &dflags))
2296 		info->flags |= GPIO_V2_LINE_FLAG_OPEN_DRAIN;
2297 	if (test_bit(FLAG_OPEN_SOURCE, &dflags))
2298 		info->flags |= GPIO_V2_LINE_FLAG_OPEN_SOURCE;
2299 
2300 	if (test_bit(FLAG_BIAS_DISABLE, &dflags))
2301 		info->flags |= GPIO_V2_LINE_FLAG_BIAS_DISABLED;
2302 	if (test_bit(FLAG_PULL_DOWN, &dflags))
2303 		info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN;
2304 	if (test_bit(FLAG_PULL_UP, &dflags))
2305 		info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_UP;
2306 
2307 	if (test_bit(FLAG_EDGE_RISING, &dflags))
2308 		info->flags |= GPIO_V2_LINE_FLAG_EDGE_RISING;
2309 	if (test_bit(FLAG_EDGE_FALLING, &dflags))
2310 		info->flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING;
2311 
2312 	if (test_bit(FLAG_EVENT_CLOCK_REALTIME, &dflags))
2313 		info->flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME;
2314 	else if (test_bit(FLAG_EVENT_CLOCK_HTE, &dflags))
2315 		info->flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE;
2316 
2317 	debounce_period_us = READ_ONCE(desc->debounce_period_us);
2318 	if (debounce_period_us) {
2319 		info->attrs[info->num_attrs].id = GPIO_V2_LINE_ATTR_ID_DEBOUNCE;
2320 		info->attrs[info->num_attrs].debounce_period_us =
2321 							debounce_period_us;
2322 		info->num_attrs++;
2323 	}
2324 }
2325 
2326 struct gpio_chardev_data {
2327 	struct gpio_device *gdev;
2328 	wait_queue_head_t wait;
2329 	DECLARE_KFIFO(events, struct gpio_v2_line_info_changed, 32);
2330 	struct notifier_block lineinfo_changed_nb;
2331 	struct notifier_block device_unregistered_nb;
2332 	unsigned long *watched_lines;
2333 #ifdef CONFIG_GPIO_CDEV_V1
2334 	atomic_t watch_abi_version;
2335 #endif
2336 	struct file *fp;
2337 };
2338 
chipinfo_get(struct gpio_chardev_data * cdev,void __user * ip)2339 static int chipinfo_get(struct gpio_chardev_data *cdev, void __user *ip)
2340 {
2341 	struct gpio_device *gdev = cdev->gdev;
2342 	struct gpiochip_info chipinfo;
2343 
2344 	memset(&chipinfo, 0, sizeof(chipinfo));
2345 
2346 	strscpy(chipinfo.name, dev_name(&gdev->dev), sizeof(chipinfo.name));
2347 	strscpy(chipinfo.label, gdev->label, sizeof(chipinfo.label));
2348 	chipinfo.lines = gdev->ngpio;
2349 	if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
2350 		return -EFAULT;
2351 	return 0;
2352 }
2353 
2354 #ifdef CONFIG_GPIO_CDEV_V1
2355 /*
2356  * returns 0 if the versions match, else the previously selected ABI version
2357  */
lineinfo_ensure_abi_version(struct gpio_chardev_data * cdata,unsigned int version)2358 static int lineinfo_ensure_abi_version(struct gpio_chardev_data *cdata,
2359 				       unsigned int version)
2360 {
2361 	int abiv = atomic_cmpxchg(&cdata->watch_abi_version, 0, version);
2362 
2363 	if (abiv == version)
2364 		return 0;
2365 
2366 	return abiv;
2367 }
2368 
lineinfo_get_v1(struct gpio_chardev_data * cdev,void __user * ip,bool watch)2369 static int lineinfo_get_v1(struct gpio_chardev_data *cdev, void __user *ip,
2370 			   bool watch)
2371 {
2372 	struct gpio_desc *desc;
2373 	struct gpioline_info lineinfo;
2374 	struct gpio_v2_line_info lineinfo_v2;
2375 
2376 	if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
2377 		return -EFAULT;
2378 
2379 	/* this doubles as a range check on line_offset */
2380 	desc = gpio_device_get_desc(cdev->gdev, lineinfo.line_offset);
2381 	if (IS_ERR(desc))
2382 		return PTR_ERR(desc);
2383 
2384 	if (watch) {
2385 		if (lineinfo_ensure_abi_version(cdev, 1))
2386 			return -EPERM;
2387 
2388 		if (test_and_set_bit(lineinfo.line_offset, cdev->watched_lines))
2389 			return -EBUSY;
2390 	}
2391 
2392 	gpio_desc_to_lineinfo(desc, &lineinfo_v2, false);
2393 	gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);
2394 
2395 	if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
2396 		if (watch)
2397 			clear_bit(lineinfo.line_offset, cdev->watched_lines);
2398 		return -EFAULT;
2399 	}
2400 
2401 	return 0;
2402 }
2403 #endif
2404 
lineinfo_get(struct gpio_chardev_data * cdev,void __user * ip,bool watch)2405 static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip,
2406 			bool watch)
2407 {
2408 	struct gpio_desc *desc;
2409 	struct gpio_v2_line_info lineinfo;
2410 
2411 	if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
2412 		return -EFAULT;
2413 
2414 	if (!mem_is_zero(lineinfo.padding, sizeof(lineinfo.padding)))
2415 		return -EINVAL;
2416 
2417 	desc = gpio_device_get_desc(cdev->gdev, lineinfo.offset);
2418 	if (IS_ERR(desc))
2419 		return PTR_ERR(desc);
2420 
2421 	if (watch) {
2422 #ifdef CONFIG_GPIO_CDEV_V1
2423 		if (lineinfo_ensure_abi_version(cdev, 2))
2424 			return -EPERM;
2425 #endif
2426 		if (test_and_set_bit(lineinfo.offset, cdev->watched_lines))
2427 			return -EBUSY;
2428 	}
2429 	gpio_desc_to_lineinfo(desc, &lineinfo, false);
2430 
2431 	if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
2432 		if (watch)
2433 			clear_bit(lineinfo.offset, cdev->watched_lines);
2434 		return -EFAULT;
2435 	}
2436 
2437 	return 0;
2438 }
2439 
lineinfo_unwatch(struct gpio_chardev_data * cdev,void __user * ip)2440 static int lineinfo_unwatch(struct gpio_chardev_data *cdev, void __user *ip)
2441 {
2442 	__u32 offset;
2443 
2444 	if (copy_from_user(&offset, ip, sizeof(offset)))
2445 		return -EFAULT;
2446 
2447 	if (offset >= cdev->gdev->ngpio)
2448 		return -EINVAL;
2449 
2450 	if (!test_and_clear_bit(offset, cdev->watched_lines))
2451 		return -EBUSY;
2452 
2453 	return 0;
2454 }
2455 
2456 /*
2457  * gpio_ioctl() - ioctl handler for the GPIO chardev
2458  */
gpio_ioctl(struct file * file,unsigned int cmd,unsigned long arg)2459 static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2460 {
2461 	struct gpio_chardev_data *cdev = file->private_data;
2462 	struct gpio_device *gdev = cdev->gdev;
2463 	void __user *ip = (void __user *)arg;
2464 
2465 	guard(srcu)(&gdev->srcu);
2466 
2467 	/* We fail any subsequent ioctl():s when the chip is gone */
2468 	if (!rcu_access_pointer(gdev->chip))
2469 		return -ENODEV;
2470 
2471 	/* Fill in the struct and pass to userspace */
2472 	switch (cmd) {
2473 	case GPIO_GET_CHIPINFO_IOCTL:
2474 		return chipinfo_get(cdev, ip);
2475 #ifdef CONFIG_GPIO_CDEV_V1
2476 	case GPIO_GET_LINEHANDLE_IOCTL:
2477 		return linehandle_create(gdev, ip);
2478 	case GPIO_GET_LINEEVENT_IOCTL:
2479 		return lineevent_create(gdev, ip);
2480 	case GPIO_GET_LINEINFO_IOCTL:
2481 		return lineinfo_get_v1(cdev, ip, false);
2482 	case GPIO_GET_LINEINFO_WATCH_IOCTL:
2483 		return lineinfo_get_v1(cdev, ip, true);
2484 #endif /* CONFIG_GPIO_CDEV_V1 */
2485 	case GPIO_V2_GET_LINEINFO_IOCTL:
2486 		return lineinfo_get(cdev, ip, false);
2487 	case GPIO_V2_GET_LINEINFO_WATCH_IOCTL:
2488 		return lineinfo_get(cdev, ip, true);
2489 	case GPIO_V2_GET_LINE_IOCTL:
2490 		return linereq_create(gdev, ip);
2491 	case GPIO_GET_LINEINFO_UNWATCH_IOCTL:
2492 		return lineinfo_unwatch(cdev, ip);
2493 	default:
2494 		return -EINVAL;
2495 	}
2496 }
2497 
2498 #ifdef CONFIG_COMPAT
gpio_ioctl_compat(struct file * file,unsigned int cmd,unsigned long arg)2499 static long gpio_ioctl_compat(struct file *file, unsigned int cmd,
2500 			      unsigned long arg)
2501 {
2502 	return gpio_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2503 }
2504 #endif
2505 
2506 struct lineinfo_changed_ctx {
2507 	struct work_struct work;
2508 	struct gpio_v2_line_info_changed chg;
2509 	struct gpio_device *gdev;
2510 	struct gpio_chardev_data *cdev;
2511 };
2512 
lineinfo_changed_func(struct work_struct * work)2513 static void lineinfo_changed_func(struct work_struct *work)
2514 {
2515 	struct lineinfo_changed_ctx *ctx =
2516 			container_of(work, struct lineinfo_changed_ctx, work);
2517 	struct gpio_chip *gc;
2518 	int ret;
2519 
2520 	if (!(ctx->chg.info.flags & GPIO_V2_LINE_FLAG_USED)) {
2521 		/*
2522 		 * If nobody set the USED flag earlier, let's see with pinctrl
2523 		 * now. We're doing this late because it's a sleeping function.
2524 		 * Pin functions are in general much more static and while it's
2525 		 * not 100% bullet-proof, it's good enough for most cases.
2526 		 */
2527 		scoped_guard(srcu, &ctx->gdev->srcu) {
2528 			gc = srcu_dereference(ctx->gdev->chip, &ctx->gdev->srcu);
2529 			if (gc &&
2530 			    !pinctrl_gpio_can_use_line(gc, ctx->chg.info.offset))
2531 				ctx->chg.info.flags |= GPIO_V2_LINE_FLAG_USED;
2532 		}
2533 	}
2534 
2535 	ret = kfifo_in_spinlocked(&ctx->cdev->events, &ctx->chg, 1,
2536 				  &ctx->cdev->wait.lock);
2537 	if (ret)
2538 		wake_up_poll(&ctx->cdev->wait, EPOLLIN);
2539 	else
2540 		pr_debug_ratelimited("lineinfo event FIFO is full - event dropped\n");
2541 
2542 	gpio_device_put(ctx->gdev);
2543 	fput(ctx->cdev->fp);
2544 	kfree(ctx);
2545 }
2546 
lineinfo_changed_notify(struct notifier_block * nb,unsigned long action,void * data)2547 static int lineinfo_changed_notify(struct notifier_block *nb,
2548 				   unsigned long action, void *data)
2549 {
2550 	struct gpio_chardev_data *cdev =
2551 		container_of(nb, struct gpio_chardev_data, lineinfo_changed_nb);
2552 	struct lineinfo_changed_ctx *ctx;
2553 	struct gpio_desc *desc = data;
2554 
2555 	if (!test_bit(gpio_chip_hwgpio(desc), cdev->watched_lines))
2556 		return NOTIFY_DONE;
2557 
2558 	/*
2559 	 * If this is called from atomic context (for instance: with a spinlock
2560 	 * taken by the atomic notifier chain), any sleeping calls must be done
2561 	 * outside of this function in process context of the dedicated
2562 	 * workqueue.
2563 	 *
2564 	 * Let's gather as much info as possible from the descriptor and
2565 	 * postpone just the call to pinctrl_gpio_can_use_line() until the work
2566 	 * is executed.
2567 	 */
2568 
2569 	ctx = kzalloc(sizeof(*ctx), GFP_ATOMIC);
2570 	if (!ctx) {
2571 		pr_err("Failed to allocate memory for line info notification\n");
2572 		return NOTIFY_DONE;
2573 	}
2574 
2575 	ctx->chg.event_type = action;
2576 	ctx->chg.timestamp_ns = ktime_get_ns();
2577 	gpio_desc_to_lineinfo(desc, &ctx->chg.info, true);
2578 	/* Keep the GPIO device alive until we emit the event. */
2579 	ctx->gdev = gpio_device_get(desc->gdev);
2580 	ctx->cdev = cdev;
2581 	/* Keep the file descriptor alive too. */
2582 	get_file(ctx->cdev->fp);
2583 
2584 	INIT_WORK(&ctx->work, lineinfo_changed_func);
2585 	queue_work(ctx->gdev->line_state_wq, &ctx->work);
2586 
2587 	return NOTIFY_OK;
2588 }
2589 
gpio_device_unregistered_notify(struct notifier_block * nb,unsigned long action,void * data)2590 static int gpio_device_unregistered_notify(struct notifier_block *nb,
2591 					   unsigned long action, void *data)
2592 {
2593 	struct gpio_chardev_data *cdev = container_of(nb,
2594 						      struct gpio_chardev_data,
2595 						      device_unregistered_nb);
2596 
2597 	wake_up_poll(&cdev->wait, EPOLLIN | EPOLLERR);
2598 
2599 	return NOTIFY_OK;
2600 }
2601 
lineinfo_watch_poll(struct file * file,struct poll_table_struct * pollt)2602 static __poll_t lineinfo_watch_poll(struct file *file,
2603 				    struct poll_table_struct *pollt)
2604 {
2605 	struct gpio_chardev_data *cdev = file->private_data;
2606 	__poll_t events = 0;
2607 
2608 	guard(srcu)(&cdev->gdev->srcu);
2609 
2610 	if (!rcu_access_pointer(cdev->gdev->chip))
2611 		return EPOLLHUP | EPOLLERR;
2612 
2613 	poll_wait(file, &cdev->wait, pollt);
2614 
2615 	if (!kfifo_is_empty_spinlocked_noirqsave(&cdev->events,
2616 						 &cdev->wait.lock))
2617 		events = EPOLLIN | EPOLLRDNORM;
2618 
2619 	return events;
2620 }
2621 
lineinfo_watch_read(struct file * file,char __user * buf,size_t count,loff_t * off)2622 static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
2623 				   size_t count, loff_t *off)
2624 {
2625 	struct gpio_chardev_data *cdev = file->private_data;
2626 	struct gpio_v2_line_info_changed event;
2627 	ssize_t bytes_read = 0;
2628 	int ret;
2629 	size_t event_size;
2630 
2631 	guard(srcu)(&cdev->gdev->srcu);
2632 
2633 	if (!rcu_access_pointer(cdev->gdev->chip))
2634 		return -ENODEV;
2635 
2636 #ifndef CONFIG_GPIO_CDEV_V1
2637 	event_size = sizeof(struct gpio_v2_line_info_changed);
2638 	if (count < event_size)
2639 		return -EINVAL;
2640 #endif
2641 
2642 	do {
2643 		scoped_guard(spinlock, &cdev->wait.lock) {
2644 			if (kfifo_is_empty(&cdev->events)) {
2645 				if (bytes_read)
2646 					return bytes_read;
2647 
2648 				if (file->f_flags & O_NONBLOCK)
2649 					return -EAGAIN;
2650 
2651 				ret = wait_event_interruptible_locked(cdev->wait,
2652 						!kfifo_is_empty(&cdev->events));
2653 				if (ret)
2654 					return ret;
2655 			}
2656 #ifdef CONFIG_GPIO_CDEV_V1
2657 			/* must be after kfifo check so watch_abi_version is set */
2658 			if (atomic_read(&cdev->watch_abi_version) == 2)
2659 				event_size = sizeof(struct gpio_v2_line_info_changed);
2660 			else
2661 				event_size = sizeof(struct gpioline_info_changed);
2662 			if (count < event_size)
2663 				return -EINVAL;
2664 #endif
2665 			if (kfifo_out(&cdev->events, &event, 1) != 1) {
2666 				/*
2667 				 * This should never happen - we hold the
2668 				 * lock from the moment we learned the fifo
2669 				 * is no longer empty until now.
2670 				 */
2671 				WARN(1, "failed to read from non-empty kfifo");
2672 				return -EIO;
2673 			}
2674 		}
2675 
2676 #ifdef CONFIG_GPIO_CDEV_V1
2677 		if (event_size == sizeof(struct gpio_v2_line_info_changed)) {
2678 			if (copy_to_user(buf + bytes_read, &event, event_size))
2679 				return -EFAULT;
2680 		} else {
2681 			struct gpioline_info_changed event_v1;
2682 
2683 			gpio_v2_line_info_changed_to_v1(&event, &event_v1);
2684 			if (copy_to_user(buf + bytes_read, &event_v1,
2685 					 event_size))
2686 				return -EFAULT;
2687 		}
2688 #else
2689 		if (copy_to_user(buf + bytes_read, &event, event_size))
2690 			return -EFAULT;
2691 #endif
2692 		bytes_read += event_size;
2693 	} while (count >= bytes_read + sizeof(event));
2694 
2695 	return bytes_read;
2696 }
2697 
2698 /**
2699  * gpio_chrdev_open() - open the chardev for ioctl operations
2700  * @inode: inode for this chardev
2701  * @file: file struct for storing private data
2702  *
2703  * Returns:
2704  * 0 on success, or negative errno on failure.
2705  */
gpio_chrdev_open(struct inode * inode,struct file * file)2706 static int gpio_chrdev_open(struct inode *inode, struct file *file)
2707 {
2708 	struct gpio_device *gdev = container_of(inode->i_cdev,
2709 						struct gpio_device, chrdev);
2710 	struct gpio_chardev_data *cdev;
2711 	int ret = -ENOMEM;
2712 
2713 	guard(srcu)(&gdev->srcu);
2714 
2715 	/* Fail on open if the backing gpiochip is gone */
2716 	if (!rcu_access_pointer(gdev->chip))
2717 		return -ENODEV;
2718 
2719 	cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
2720 	if (!cdev)
2721 		return -ENODEV;
2722 
2723 	cdev->watched_lines = bitmap_zalloc(gdev->ngpio, GFP_KERNEL);
2724 	if (!cdev->watched_lines)
2725 		goto out_free_cdev;
2726 
2727 	init_waitqueue_head(&cdev->wait);
2728 	INIT_KFIFO(cdev->events);
2729 	cdev->gdev = gpio_device_get(gdev);
2730 
2731 	cdev->lineinfo_changed_nb.notifier_call = lineinfo_changed_notify;
2732 	ret = atomic_notifier_chain_register(&gdev->line_state_notifier,
2733 					     &cdev->lineinfo_changed_nb);
2734 	if (ret)
2735 		goto out_free_bitmap;
2736 
2737 	cdev->device_unregistered_nb.notifier_call =
2738 					gpio_device_unregistered_notify;
2739 	ret = blocking_notifier_chain_register(&gdev->device_notifier,
2740 					       &cdev->device_unregistered_nb);
2741 	if (ret)
2742 		goto out_unregister_line_notifier;
2743 
2744 	file->private_data = cdev;
2745 	cdev->fp = file;
2746 
2747 	ret = nonseekable_open(inode, file);
2748 	if (ret)
2749 		goto out_unregister_device_notifier;
2750 
2751 	return ret;
2752 
2753 out_unregister_device_notifier:
2754 	blocking_notifier_chain_unregister(&gdev->device_notifier,
2755 					   &cdev->device_unregistered_nb);
2756 out_unregister_line_notifier:
2757 	atomic_notifier_chain_unregister(&gdev->line_state_notifier,
2758 					 &cdev->lineinfo_changed_nb);
2759 out_free_bitmap:
2760 	gpio_device_put(gdev);
2761 	bitmap_free(cdev->watched_lines);
2762 out_free_cdev:
2763 	kfree(cdev);
2764 	return ret;
2765 }
2766 
2767 /**
2768  * gpio_chrdev_release() - close chardev after ioctl operations
2769  * @inode: inode for this chardev
2770  * @file: file struct for storing private data
2771  *
2772  * Returns:
2773  * 0 on success, or negative errno on failure.
2774  */
gpio_chrdev_release(struct inode * inode,struct file * file)2775 static int gpio_chrdev_release(struct inode *inode, struct file *file)
2776 {
2777 	struct gpio_chardev_data *cdev = file->private_data;
2778 	struct gpio_device *gdev = cdev->gdev;
2779 
2780 	blocking_notifier_chain_unregister(&gdev->device_notifier,
2781 					   &cdev->device_unregistered_nb);
2782 	atomic_notifier_chain_unregister(&gdev->line_state_notifier,
2783 					 &cdev->lineinfo_changed_nb);
2784 	bitmap_free(cdev->watched_lines);
2785 	gpio_device_put(gdev);
2786 	kfree(cdev);
2787 
2788 	return 0;
2789 }
2790 
2791 static const struct file_operations gpio_fileops = {
2792 	.release = gpio_chrdev_release,
2793 	.open = gpio_chrdev_open,
2794 	.poll = lineinfo_watch_poll,
2795 	.read = lineinfo_watch_read,
2796 	.owner = THIS_MODULE,
2797 	.unlocked_ioctl = gpio_ioctl,
2798 #ifdef CONFIG_COMPAT
2799 	.compat_ioctl = gpio_ioctl_compat,
2800 #endif
2801 };
2802 
gpiolib_cdev_register(struct gpio_device * gdev,dev_t devt)2803 int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
2804 {
2805 	struct gpio_chip *gc;
2806 	int ret;
2807 
2808 	cdev_init(&gdev->chrdev, &gpio_fileops);
2809 	gdev->chrdev.owner = THIS_MODULE;
2810 	gdev->dev.devt = MKDEV(MAJOR(devt), gdev->id);
2811 
2812 	gdev->line_state_wq = alloc_ordered_workqueue("%s", WQ_HIGHPRI,
2813 						      dev_name(&gdev->dev));
2814 	if (!gdev->line_state_wq)
2815 		return -ENOMEM;
2816 
2817 	ret = cdev_device_add(&gdev->chrdev, &gdev->dev);
2818 	if (ret)
2819 		return ret;
2820 
2821 	guard(srcu)(&gdev->srcu);
2822 	gc = srcu_dereference(gdev->chip, &gdev->srcu);
2823 	if (!gc)
2824 		return -ENODEV;
2825 
2826 	chip_dbg(gc, "added GPIO chardev (%d:%d)\n", MAJOR(devt), gdev->id);
2827 
2828 	return 0;
2829 }
2830 
gpiolib_cdev_unregister(struct gpio_device * gdev)2831 void gpiolib_cdev_unregister(struct gpio_device *gdev)
2832 {
2833 	destroy_workqueue(gdev->line_state_wq);
2834 	cdev_device_del(&gdev->chrdev, &gdev->dev);
2835 	blocking_notifier_call_chain(&gdev->device_notifier, 0, NULL);
2836 }
2837