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