1 // SPDX-License-Identifier: GPL-2.0-only
2 //
3 // GPIO Aggregator
4 //
5 // Copyright (C) 2019-2020 Glider bv
6 
7 #define DRV_NAME       "gpio-aggregator"
8 #define pr_fmt(fmt)	DRV_NAME ": " fmt
9 
10 #include <linux/bitmap.h>
11 #include <linux/bitops.h>
12 #include <linux/ctype.h>
13 #include <linux/gpio.h>
14 #include <linux/gpio/consumer.h>
15 #include <linux/gpio/driver.h>
16 #include <linux/gpio/machine.h>
17 #include <linux/idr.h>
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/mutex.h>
21 #include <linux/overflow.h>
22 #include <linux/platform_device.h>
23 #include <linux/spinlock.h>
24 #include <linux/string.h>
25 
26 
27 /*
28  * GPIO Aggregator sysfs interface
29  */
30 
31 struct gpio_aggregator {
32 	struct gpiod_lookup_table *lookups;
33 	struct platform_device *pdev;
34 	char args[];
35 };
36 
37 static DEFINE_MUTEX(gpio_aggregator_lock);	/* protects idr */
38 static DEFINE_IDR(gpio_aggregator_idr);
39 
40 static char *get_arg(char **args)
41 {
42 	char *start, *end;
43 
44 	start = skip_spaces(*args);
45 	if (!*start)
46 		return NULL;
47 
48 	if (*start == '"') {
49 		/* Quoted arg */
50 		end = strchr(++start, '"');
51 		if (!end)
52 			return ERR_PTR(-EINVAL);
53 	} else {
54 		/* Unquoted arg */
55 		for (end = start; *end && !isspace(*end); end++) ;
56 	}
57 
58 	if (*end)
59 		*end++ = '\0';
60 
61 	*args = end;
62 	return start;
63 }
64 
65 static bool isrange(const char *s)
66 {
67 	size_t n;
68 
69 	if (IS_ERR_OR_NULL(s))
70 		return false;
71 
72 	while (1) {
73 		n = strspn(s, "0123456789");
74 		if (!n)
75 			return false;
76 
77 		s += n;
78 
79 		switch (*s++) {
80 		case '\0':
81 			return true;
82 
83 		case '-':
84 		case ',':
85 			break;
86 
87 		default:
88 			return false;
89 		}
90 	}
91 }
92 
93 static int aggr_add_gpio(struct gpio_aggregator *aggr, const char *key,
94 			 int hwnum, unsigned int *n)
95 {
96 	struct gpiod_lookup_table *lookups;
97 
98 	lookups = krealloc(aggr->lookups, struct_size(lookups, table, *n + 2),
99 			   GFP_KERNEL);
100 	if (!lookups)
101 		return -ENOMEM;
102 
103 	lookups->table[*n] =
104 		(struct gpiod_lookup)GPIO_LOOKUP_IDX(key, hwnum, NULL, *n, 0);
105 
106 	(*n)++;
107 	memset(&lookups->table[*n], 0, sizeof(lookups->table[*n]));
108 
109 	aggr->lookups = lookups;
110 	return 0;
111 }
112 
113 static int aggr_parse(struct gpio_aggregator *aggr)
114 {
115 	char *args = aggr->args;
116 	unsigned long *bitmap;
117 	unsigned int i, n = 0;
118 	char *name, *offsets;
119 	int error = 0;
120 
121 	bitmap = bitmap_alloc(ARCH_NR_GPIOS, GFP_KERNEL);
122 	if (!bitmap)
123 		return -ENOMEM;
124 
125 	for (name = get_arg(&args), offsets = get_arg(&args); name;
126 	     offsets = get_arg(&args)) {
127 		if (IS_ERR(name)) {
128 			pr_err("Cannot get GPIO specifier: %pe\n", name);
129 			error = PTR_ERR(name);
130 			goto free_bitmap;
131 		}
132 
133 		if (!isrange(offsets)) {
134 			/* Named GPIO line */
135 			error = aggr_add_gpio(aggr, name, U16_MAX, &n);
136 			if (error)
137 				goto free_bitmap;
138 
139 			name = offsets;
140 			continue;
141 		}
142 
143 		/* GPIO chip + offset(s) */
144 		error = bitmap_parselist(offsets, bitmap, ARCH_NR_GPIOS);
145 		if (error) {
146 			pr_err("Cannot parse %s: %d\n", offsets, error);
147 			goto free_bitmap;
148 		}
149 
150 		for_each_set_bit(i, bitmap, ARCH_NR_GPIOS) {
151 			error = aggr_add_gpio(aggr, name, i, &n);
152 			if (error)
153 				goto free_bitmap;
154 		}
155 
156 		name = get_arg(&args);
157 	}
158 
159 	if (!n) {
160 		pr_err("No GPIOs specified\n");
161 		error = -EINVAL;
162 	}
163 
164 free_bitmap:
165 	bitmap_free(bitmap);
166 	return error;
167 }
168 
169 static ssize_t new_device_store(struct device_driver *driver, const char *buf,
170 				size_t count)
171 {
172 	struct gpio_aggregator *aggr;
173 	struct platform_device *pdev;
174 	int res, id;
175 
176 	/* kernfs guarantees string termination, so count + 1 is safe */
177 	aggr = kzalloc(sizeof(*aggr) + count + 1, GFP_KERNEL);
178 	if (!aggr)
179 		return -ENOMEM;
180 
181 	memcpy(aggr->args, buf, count + 1);
182 
183 	aggr->lookups = kzalloc(struct_size(aggr->lookups, table, 1),
184 				GFP_KERNEL);
185 	if (!aggr->lookups) {
186 		res = -ENOMEM;
187 		goto free_ga;
188 	}
189 
190 	mutex_lock(&gpio_aggregator_lock);
191 	id = idr_alloc(&gpio_aggregator_idr, aggr, 0, 0, GFP_KERNEL);
192 	mutex_unlock(&gpio_aggregator_lock);
193 
194 	if (id < 0) {
195 		res = id;
196 		goto free_table;
197 	}
198 
199 	aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, id);
200 	if (!aggr->lookups->dev_id) {
201 		res = -ENOMEM;
202 		goto remove_idr;
203 	}
204 
205 	res = aggr_parse(aggr);
206 	if (res)
207 		goto free_dev_id;
208 
209 	gpiod_add_lookup_table(aggr->lookups);
210 
211 	pdev = platform_device_register_simple(DRV_NAME, id, NULL, 0);
212 	if (IS_ERR(pdev)) {
213 		res = PTR_ERR(pdev);
214 		goto remove_table;
215 	}
216 
217 	aggr->pdev = pdev;
218 	return count;
219 
220 remove_table:
221 	gpiod_remove_lookup_table(aggr->lookups);
222 free_dev_id:
223 	kfree(aggr->lookups->dev_id);
224 remove_idr:
225 	mutex_lock(&gpio_aggregator_lock);
226 	idr_remove(&gpio_aggregator_idr, id);
227 	mutex_unlock(&gpio_aggregator_lock);
228 free_table:
229 	kfree(aggr->lookups);
230 free_ga:
231 	kfree(aggr);
232 	return res;
233 }
234 
235 static DRIVER_ATTR_WO(new_device);
236 
237 static void gpio_aggregator_free(struct gpio_aggregator *aggr)
238 {
239 	platform_device_unregister(aggr->pdev);
240 	gpiod_remove_lookup_table(aggr->lookups);
241 	kfree(aggr->lookups->dev_id);
242 	kfree(aggr->lookups);
243 	kfree(aggr);
244 }
245 
246 static ssize_t delete_device_store(struct device_driver *driver,
247 				   const char *buf, size_t count)
248 {
249 	struct gpio_aggregator *aggr;
250 	unsigned int id;
251 	int error;
252 
253 	if (!str_has_prefix(buf, DRV_NAME "."))
254 		return -EINVAL;
255 
256 	error = kstrtouint(buf + strlen(DRV_NAME "."), 10, &id);
257 	if (error)
258 		return error;
259 
260 	mutex_lock(&gpio_aggregator_lock);
261 	aggr = idr_remove(&gpio_aggregator_idr, id);
262 	mutex_unlock(&gpio_aggregator_lock);
263 	if (!aggr)
264 		return -ENOENT;
265 
266 	gpio_aggregator_free(aggr);
267 	return count;
268 }
269 static DRIVER_ATTR_WO(delete_device);
270 
271 static struct attribute *gpio_aggregator_attrs[] = {
272 	&driver_attr_new_device.attr,
273 	&driver_attr_delete_device.attr,
274 	NULL,
275 };
276 ATTRIBUTE_GROUPS(gpio_aggregator);
277 
278 static int __exit gpio_aggregator_idr_remove(int id, void *p, void *data)
279 {
280 	gpio_aggregator_free(p);
281 	return 0;
282 }
283 
284 static void __exit gpio_aggregator_remove_all(void)
285 {
286 	mutex_lock(&gpio_aggregator_lock);
287 	idr_for_each(&gpio_aggregator_idr, gpio_aggregator_idr_remove, NULL);
288 	idr_destroy(&gpio_aggregator_idr);
289 	mutex_unlock(&gpio_aggregator_lock);
290 }
291 
292 
293 /*
294  *  GPIO Forwarder
295  */
296 
297 struct gpiochip_fwd {
298 	struct gpio_chip chip;
299 	struct gpio_desc **descs;
300 	union {
301 		struct mutex mlock;	/* protects tmp[] if can_sleep */
302 		spinlock_t slock;	/* protects tmp[] if !can_sleep */
303 	};
304 	unsigned long tmp[];		/* values and descs for multiple ops */
305 };
306 
307 static int gpio_fwd_get_direction(struct gpio_chip *chip, unsigned int offset)
308 {
309 	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
310 
311 	return gpiod_get_direction(fwd->descs[offset]);
312 }
313 
314 static int gpio_fwd_direction_input(struct gpio_chip *chip, unsigned int offset)
315 {
316 	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
317 
318 	return gpiod_direction_input(fwd->descs[offset]);
319 }
320 
321 static int gpio_fwd_direction_output(struct gpio_chip *chip,
322 				     unsigned int offset, int value)
323 {
324 	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
325 
326 	return gpiod_direction_output(fwd->descs[offset], value);
327 }
328 
329 static int gpio_fwd_get(struct gpio_chip *chip, unsigned int offset)
330 {
331 	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
332 
333 	return gpiod_get_value(fwd->descs[offset]);
334 }
335 
336 static int gpio_fwd_get_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
337 				 unsigned long *bits)
338 {
339 	struct gpio_desc **descs;
340 	unsigned long *values;
341 	unsigned int i, j = 0;
342 	int error;
343 
344 	/* Both values bitmap and desc pointers are stored in tmp[] */
345 	values = &fwd->tmp[0];
346 	descs = (void *)&fwd->tmp[BITS_TO_LONGS(fwd->chip.ngpio)];
347 
348 	bitmap_clear(values, 0, fwd->chip.ngpio);
349 	for_each_set_bit(i, mask, fwd->chip.ngpio)
350 		descs[j++] = fwd->descs[i];
351 
352 	error = gpiod_get_array_value(j, descs, NULL, values);
353 	if (error)
354 		return error;
355 
356 	j = 0;
357 	for_each_set_bit(i, mask, fwd->chip.ngpio)
358 		__assign_bit(i, bits, test_bit(j++, values));
359 
360 	return 0;
361 }
362 
363 static int gpio_fwd_get_multiple_locked(struct gpio_chip *chip,
364 					unsigned long *mask, unsigned long *bits)
365 {
366 	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
367 	unsigned long flags;
368 	int error;
369 
370 	if (chip->can_sleep) {
371 		mutex_lock(&fwd->mlock);
372 		error = gpio_fwd_get_multiple(fwd, mask, bits);
373 		mutex_unlock(&fwd->mlock);
374 	} else {
375 		spin_lock_irqsave(&fwd->slock, flags);
376 		error = gpio_fwd_get_multiple(fwd, mask, bits);
377 		spin_unlock_irqrestore(&fwd->slock, flags);
378 	}
379 
380 	return error;
381 }
382 
383 static void gpio_fwd_set(struct gpio_chip *chip, unsigned int offset, int value)
384 {
385 	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
386 
387 	gpiod_set_value(fwd->descs[offset], value);
388 }
389 
390 static void gpio_fwd_set_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
391 				  unsigned long *bits)
392 {
393 	struct gpio_desc **descs;
394 	unsigned long *values;
395 	unsigned int i, j = 0;
396 
397 	/* Both values bitmap and desc pointers are stored in tmp[] */
398 	values = &fwd->tmp[0];
399 	descs = (void *)&fwd->tmp[BITS_TO_LONGS(fwd->chip.ngpio)];
400 
401 	for_each_set_bit(i, mask, fwd->chip.ngpio) {
402 		__assign_bit(j, values, test_bit(i, bits));
403 		descs[j++] = fwd->descs[i];
404 	}
405 
406 	gpiod_set_array_value(j, descs, NULL, values);
407 }
408 
409 static void gpio_fwd_set_multiple_locked(struct gpio_chip *chip,
410 					 unsigned long *mask, unsigned long *bits)
411 {
412 	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
413 	unsigned long flags;
414 
415 	if (chip->can_sleep) {
416 		mutex_lock(&fwd->mlock);
417 		gpio_fwd_set_multiple(fwd, mask, bits);
418 		mutex_unlock(&fwd->mlock);
419 	} else {
420 		spin_lock_irqsave(&fwd->slock, flags);
421 		gpio_fwd_set_multiple(fwd, mask, bits);
422 		spin_unlock_irqrestore(&fwd->slock, flags);
423 	}
424 }
425 
426 static int gpio_fwd_set_config(struct gpio_chip *chip, unsigned int offset,
427 			       unsigned long config)
428 {
429 	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
430 
431 	return gpiod_set_config(fwd->descs[offset], config);
432 }
433 
434 /**
435  * gpiochip_fwd_create() - Create a new GPIO forwarder
436  * @dev: Parent device pointer
437  * @ngpios: Number of GPIOs in the forwarder.
438  * @descs: Array containing the GPIO descriptors to forward to.
439  *         This array must contain @ngpios entries, and must not be deallocated
440  *         before the forwarder has been destroyed again.
441  *
442  * This function creates a new gpiochip, which forwards all GPIO operations to
443  * the passed GPIO descriptors.
444  *
445  * Return: An opaque object pointer, or an ERR_PTR()-encoded negative error
446  *         code on failure.
447  */
448 static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
449 						unsigned int ngpios,
450 						struct gpio_desc *descs[])
451 {
452 	const char *label = dev_name(dev);
453 	struct gpiochip_fwd *fwd;
454 	struct gpio_chip *chip;
455 	unsigned int i;
456 	int error;
457 
458 	fwd = devm_kzalloc(dev, struct_size(fwd, tmp,
459 			   BITS_TO_LONGS(ngpios) + ngpios), GFP_KERNEL);
460 	if (!fwd)
461 		return ERR_PTR(-ENOMEM);
462 
463 	chip = &fwd->chip;
464 
465 	/*
466 	 * If any of the GPIO lines are sleeping, then the entire forwarder
467 	 * will be sleeping.
468 	 * If any of the chips support .set_config(), then the forwarder will
469 	 * support setting configs.
470 	 */
471 	for (i = 0; i < ngpios; i++) {
472 		struct gpio_chip *parent = gpiod_to_chip(descs[i]);
473 
474 		dev_dbg(dev, "%u => gpio-%d\n", i, desc_to_gpio(descs[i]));
475 
476 		if (gpiod_cansleep(descs[i]))
477 			chip->can_sleep = true;
478 		if (parent && parent->set_config)
479 			chip->set_config = gpio_fwd_set_config;
480 	}
481 
482 	chip->label = label;
483 	chip->parent = dev;
484 	chip->owner = THIS_MODULE;
485 	chip->get_direction = gpio_fwd_get_direction;
486 	chip->direction_input = gpio_fwd_direction_input;
487 	chip->direction_output = gpio_fwd_direction_output;
488 	chip->get = gpio_fwd_get;
489 	chip->get_multiple = gpio_fwd_get_multiple_locked;
490 	chip->set = gpio_fwd_set;
491 	chip->set_multiple = gpio_fwd_set_multiple_locked;
492 	chip->base = -1;
493 	chip->ngpio = ngpios;
494 	fwd->descs = descs;
495 
496 	if (chip->can_sleep)
497 		mutex_init(&fwd->mlock);
498 	else
499 		spin_lock_init(&fwd->slock);
500 
501 	error = devm_gpiochip_add_data(dev, chip, fwd);
502 	if (error)
503 		return ERR_PTR(error);
504 
505 	return fwd;
506 }
507 
508 
509 /*
510  *  GPIO Aggregator platform device
511  */
512 
513 static int gpio_aggregator_probe(struct platform_device *pdev)
514 {
515 	struct device *dev = &pdev->dev;
516 	struct gpio_desc **descs;
517 	struct gpiochip_fwd *fwd;
518 	int i, n;
519 
520 	n = gpiod_count(dev, NULL);
521 	if (n < 0)
522 		return n;
523 
524 	descs = devm_kmalloc_array(dev, n, sizeof(*descs), GFP_KERNEL);
525 	if (!descs)
526 		return -ENOMEM;
527 
528 	for (i = 0; i < n; i++) {
529 		descs[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
530 		if (IS_ERR(descs[i]))
531 			return PTR_ERR(descs[i]);
532 	}
533 
534 	fwd = gpiochip_fwd_create(dev, n, descs);
535 	if (IS_ERR(fwd))
536 		return PTR_ERR(fwd);
537 
538 	platform_set_drvdata(pdev, fwd);
539 	return 0;
540 }
541 
542 #ifdef CONFIG_OF
543 static const struct of_device_id gpio_aggregator_dt_ids[] = {
544 	/*
545 	 * Add GPIO-operated devices controlled from userspace below,
546 	 * or use "driver_override" in sysfs
547 	 */
548 	{},
549 };
550 MODULE_DEVICE_TABLE(of, gpio_aggregator_dt_ids);
551 #endif
552 
553 static struct platform_driver gpio_aggregator_driver = {
554 	.probe = gpio_aggregator_probe,
555 	.driver = {
556 		.name = DRV_NAME,
557 		.groups = gpio_aggregator_groups,
558 		.of_match_table = of_match_ptr(gpio_aggregator_dt_ids),
559 	},
560 };
561 
562 static int __init gpio_aggregator_init(void)
563 {
564 	return platform_driver_register(&gpio_aggregator_driver);
565 }
566 module_init(gpio_aggregator_init);
567 
568 static void __exit gpio_aggregator_exit(void)
569 {
570 	gpio_aggregator_remove_all();
571 	platform_driver_unregister(&gpio_aggregator_driver);
572 }
573 module_exit(gpio_aggregator_exit);
574 
575 MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
576 MODULE_DESCRIPTION("GPIO Aggregator");
577 MODULE_LICENSE("GPL v2");
578