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