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/delay.h>
14#include <linux/idr.h>
15#include <linux/kernel.h>
16#include <linux/mod_devicetable.h>
17#include <linux/module.h>
18#include <linux/mutex.h>
19#include <linux/overflow.h>
20#include <linux/platform_device.h>
21#include <linux/property.h>
22#include <linux/slab.h>
23#include <linux/spinlock.h>
24#include <linux/string.h>
25
26#include <linux/gpio/consumer.h>
27#include <linux/gpio/driver.h>
28#include <linux/gpio/machine.h>
29
30#define AGGREGATOR_MAX_GPIOS 512
31
32/*
33 * GPIO Aggregator sysfs interface
34 */
35
36struct gpio_aggregator {
37	struct gpiod_lookup_table *lookups;
38	struct platform_device *pdev;
39	char args[];
40};
41
42static DEFINE_MUTEX(gpio_aggregator_lock);	/* protects idr */
43static DEFINE_IDR(gpio_aggregator_idr);
44
45static int aggr_add_gpio(struct gpio_aggregator *aggr, const char *key,
46			 int hwnum, unsigned int *n)
47{
48	struct gpiod_lookup_table *lookups;
49
50	lookups = krealloc(aggr->lookups, struct_size(lookups, table, *n + 2),
51			   GFP_KERNEL);
52	if (!lookups)
53		return -ENOMEM;
54
55	lookups->table[*n] = GPIO_LOOKUP_IDX(key, hwnum, NULL, *n, 0);
56
57	(*n)++;
58	memset(&lookups->table[*n], 0, sizeof(lookups->table[*n]));
59
60	aggr->lookups = lookups;
61	return 0;
62}
63
64static int aggr_parse(struct gpio_aggregator *aggr)
65{
66	char *args = skip_spaces(aggr->args);
67	char *name, *offsets, *p;
68	unsigned long *bitmap;
69	unsigned int i, n = 0;
70	int error = 0;
71
72	bitmap = bitmap_alloc(AGGREGATOR_MAX_GPIOS, GFP_KERNEL);
73	if (!bitmap)
74		return -ENOMEM;
75
76	args = next_arg(args, &name, &p);
77	while (*args) {
78		args = next_arg(args, &offsets, &p);
79
80		p = get_options(offsets, 0, &error);
81		if (error == 0 || *p) {
82			/* Named GPIO line */
83			error = aggr_add_gpio(aggr, name, U16_MAX, &n);
84			if (error)
85				goto free_bitmap;
86
87			name = offsets;
88			continue;
89		}
90
91		/* GPIO chip + offset(s) */
92		error = bitmap_parselist(offsets, bitmap, AGGREGATOR_MAX_GPIOS);
93		if (error) {
94			pr_err("Cannot parse %s: %d\n", offsets, error);
95			goto free_bitmap;
96		}
97
98		for_each_set_bit(i, bitmap, AGGREGATOR_MAX_GPIOS) {
99			error = aggr_add_gpio(aggr, name, i, &n);
100			if (error)
101				goto free_bitmap;
102		}
103
104		args = next_arg(args, &name, &p);
105	}
106
107	if (!n) {
108		pr_err("No GPIOs specified\n");
109		error = -EINVAL;
110	}
111
112free_bitmap:
113	bitmap_free(bitmap);
114	return error;
115}
116
117static ssize_t new_device_store(struct device_driver *driver, const char *buf,
118				size_t count)
119{
120	struct gpio_aggregator *aggr;
121	struct platform_device *pdev;
122	int res, id;
123
124	/* kernfs guarantees string termination, so count + 1 is safe */
125	aggr = kzalloc(sizeof(*aggr) + count + 1, GFP_KERNEL);
126	if (!aggr)
127		return -ENOMEM;
128
129	memcpy(aggr->args, buf, count + 1);
130
131	aggr->lookups = kzalloc(struct_size(aggr->lookups, table, 1),
132				GFP_KERNEL);
133	if (!aggr->lookups) {
134		res = -ENOMEM;
135		goto free_ga;
136	}
137
138	mutex_lock(&gpio_aggregator_lock);
139	id = idr_alloc(&gpio_aggregator_idr, aggr, 0, 0, GFP_KERNEL);
140	mutex_unlock(&gpio_aggregator_lock);
141
142	if (id < 0) {
143		res = id;
144		goto free_table;
145	}
146
147	aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, id);
148	if (!aggr->lookups->dev_id) {
149		res = -ENOMEM;
150		goto remove_idr;
151	}
152
153	res = aggr_parse(aggr);
154	if (res)
155		goto free_dev_id;
156
157	gpiod_add_lookup_table(aggr->lookups);
158
159	pdev = platform_device_register_simple(DRV_NAME, id, NULL, 0);
160	if (IS_ERR(pdev)) {
161		res = PTR_ERR(pdev);
162		goto remove_table;
163	}
164
165	aggr->pdev = pdev;
166	return count;
167
168remove_table:
169	gpiod_remove_lookup_table(aggr->lookups);
170free_dev_id:
171	kfree(aggr->lookups->dev_id);
172remove_idr:
173	mutex_lock(&gpio_aggregator_lock);
174	idr_remove(&gpio_aggregator_idr, id);
175	mutex_unlock(&gpio_aggregator_lock);
176free_table:
177	kfree(aggr->lookups);
178free_ga:
179	kfree(aggr);
180	return res;
181}
182
183static DRIVER_ATTR_WO(new_device);
184
185static void gpio_aggregator_free(struct gpio_aggregator *aggr)
186{
187	platform_device_unregister(aggr->pdev);
188	gpiod_remove_lookup_table(aggr->lookups);
189	kfree(aggr->lookups->dev_id);
190	kfree(aggr->lookups);
191	kfree(aggr);
192}
193
194static ssize_t delete_device_store(struct device_driver *driver,
195				   const char *buf, size_t count)
196{
197	struct gpio_aggregator *aggr;
198	unsigned int id;
199	int error;
200
201	if (!str_has_prefix(buf, DRV_NAME "."))
202		return -EINVAL;
203
204	error = kstrtouint(buf + strlen(DRV_NAME "."), 10, &id);
205	if (error)
206		return error;
207
208	mutex_lock(&gpio_aggregator_lock);
209	aggr = idr_remove(&gpio_aggregator_idr, id);
210	mutex_unlock(&gpio_aggregator_lock);
211	if (!aggr)
212		return -ENOENT;
213
214	gpio_aggregator_free(aggr);
215	return count;
216}
217static DRIVER_ATTR_WO(delete_device);
218
219static struct attribute *gpio_aggregator_attrs[] = {
220	&driver_attr_new_device.attr,
221	&driver_attr_delete_device.attr,
222	NULL
223};
224ATTRIBUTE_GROUPS(gpio_aggregator);
225
226static int __exit gpio_aggregator_idr_remove(int id, void *p, void *data)
227{
228	gpio_aggregator_free(p);
229	return 0;
230}
231
232static void __exit gpio_aggregator_remove_all(void)
233{
234	mutex_lock(&gpio_aggregator_lock);
235	idr_for_each(&gpio_aggregator_idr, gpio_aggregator_idr_remove, NULL);
236	idr_destroy(&gpio_aggregator_idr);
237	mutex_unlock(&gpio_aggregator_lock);
238}
239
240
241/*
242 *  GPIO Forwarder
243 */
244
245struct gpiochip_fwd_timing {
246	u32 ramp_up_us;
247	u32 ramp_down_us;
248};
249
250struct gpiochip_fwd {
251	struct gpio_chip chip;
252	struct gpio_desc **descs;
253	union {
254		struct mutex mlock;	/* protects tmp[] if can_sleep */
255		spinlock_t slock;	/* protects tmp[] if !can_sleep */
256	};
257	struct gpiochip_fwd_timing *delay_timings;
258	unsigned long tmp[];		/* values and descs for multiple ops */
259};
260
261#define fwd_tmp_values(fwd)	&(fwd)->tmp[0]
262#define fwd_tmp_descs(fwd)	(void *)&(fwd)->tmp[BITS_TO_LONGS((fwd)->chip.ngpio)]
263
264#define fwd_tmp_size(ngpios)	(BITS_TO_LONGS((ngpios)) + (ngpios))
265
266static int gpio_fwd_get_direction(struct gpio_chip *chip, unsigned int offset)
267{
268	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
269
270	return gpiod_get_direction(fwd->descs[offset]);
271}
272
273static int gpio_fwd_direction_input(struct gpio_chip *chip, unsigned int offset)
274{
275	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
276
277	return gpiod_direction_input(fwd->descs[offset]);
278}
279
280static int gpio_fwd_direction_output(struct gpio_chip *chip,
281				     unsigned int offset, int value)
282{
283	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
284
285	return gpiod_direction_output(fwd->descs[offset], value);
286}
287
288static int gpio_fwd_get(struct gpio_chip *chip, unsigned int offset)
289{
290	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
291
292	return chip->can_sleep ? gpiod_get_value_cansleep(fwd->descs[offset])
293			       : gpiod_get_value(fwd->descs[offset]);
294}
295
296static int gpio_fwd_get_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
297				 unsigned long *bits)
298{
299	struct gpio_desc **descs = fwd_tmp_descs(fwd);
300	unsigned long *values = fwd_tmp_values(fwd);
301	unsigned int i, j = 0;
302	int error;
303
304	bitmap_clear(values, 0, fwd->chip.ngpio);
305	for_each_set_bit(i, mask, fwd->chip.ngpio)
306		descs[j++] = fwd->descs[i];
307
308	if (fwd->chip.can_sleep)
309		error = gpiod_get_array_value_cansleep(j, descs, NULL, values);
310	else
311		error = gpiod_get_array_value(j, descs, NULL, values);
312	if (error)
313		return error;
314
315	j = 0;
316	for_each_set_bit(i, mask, fwd->chip.ngpio)
317		__assign_bit(i, bits, test_bit(j++, values));
318
319	return 0;
320}
321
322static int gpio_fwd_get_multiple_locked(struct gpio_chip *chip,
323					unsigned long *mask, unsigned long *bits)
324{
325	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
326	unsigned long flags;
327	int error;
328
329	if (chip->can_sleep) {
330		mutex_lock(&fwd->mlock);
331		error = gpio_fwd_get_multiple(fwd, mask, bits);
332		mutex_unlock(&fwd->mlock);
333	} else {
334		spin_lock_irqsave(&fwd->slock, flags);
335		error = gpio_fwd_get_multiple(fwd, mask, bits);
336		spin_unlock_irqrestore(&fwd->slock, flags);
337	}
338
339	return error;
340}
341
342static void gpio_fwd_delay(struct gpio_chip *chip, unsigned int offset, int value)
343{
344	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
345	const struct gpiochip_fwd_timing *delay_timings;
346	bool is_active_low = gpiod_is_active_low(fwd->descs[offset]);
347	u32 delay_us;
348
349	delay_timings = &fwd->delay_timings[offset];
350	if ((!is_active_low && value) || (is_active_low && !value))
351		delay_us = delay_timings->ramp_up_us;
352	else
353		delay_us = delay_timings->ramp_down_us;
354	if (!delay_us)
355		return;
356
357	if (chip->can_sleep)
358		fsleep(delay_us);
359	else
360		udelay(delay_us);
361}
362
363static void gpio_fwd_set(struct gpio_chip *chip, unsigned int offset, int value)
364{
365	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
366
367	if (chip->can_sleep)
368		gpiod_set_value_cansleep(fwd->descs[offset], value);
369	else
370		gpiod_set_value(fwd->descs[offset], value);
371
372	if (fwd->delay_timings)
373		gpio_fwd_delay(chip, offset, value);
374}
375
376static void gpio_fwd_set_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
377				  unsigned long *bits)
378{
379	struct gpio_desc **descs = fwd_tmp_descs(fwd);
380	unsigned long *values = fwd_tmp_values(fwd);
381	unsigned int i, j = 0;
382
383	for_each_set_bit(i, mask, fwd->chip.ngpio) {
384		__assign_bit(j, values, test_bit(i, bits));
385		descs[j++] = fwd->descs[i];
386	}
387
388	if (fwd->chip.can_sleep)
389		gpiod_set_array_value_cansleep(j, descs, NULL, values);
390	else
391		gpiod_set_array_value(j, descs, NULL, values);
392}
393
394static void gpio_fwd_set_multiple_locked(struct gpio_chip *chip,
395					 unsigned long *mask, unsigned long *bits)
396{
397	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
398	unsigned long flags;
399
400	if (chip->can_sleep) {
401		mutex_lock(&fwd->mlock);
402		gpio_fwd_set_multiple(fwd, mask, bits);
403		mutex_unlock(&fwd->mlock);
404	} else {
405		spin_lock_irqsave(&fwd->slock, flags);
406		gpio_fwd_set_multiple(fwd, mask, bits);
407		spin_unlock_irqrestore(&fwd->slock, flags);
408	}
409}
410
411static int gpio_fwd_set_config(struct gpio_chip *chip, unsigned int offset,
412			       unsigned long config)
413{
414	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
415
416	return gpiod_set_config(fwd->descs[offset], config);
417}
418
419static int gpio_fwd_to_irq(struct gpio_chip *chip, unsigned int offset)
420{
421	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
422
423	return gpiod_to_irq(fwd->descs[offset]);
424}
425
426/*
427 * The GPIO delay provides a way to configure platform specific delays
428 * for the GPIO ramp-up or ramp-down delays. This can serve the following
429 * purposes:
430 *   - Open-drain output using an RC filter
431 */
432#define FWD_FEATURE_DELAY		BIT(0)
433
434#ifdef CONFIG_OF_GPIO
435static int gpiochip_fwd_delay_of_xlate(struct gpio_chip *chip,
436				       const struct of_phandle_args *gpiospec,
437				       u32 *flags)
438{
439	struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
440	struct gpiochip_fwd_timing *timings;
441	u32 line;
442
443	if (gpiospec->args_count != chip->of_gpio_n_cells)
444		return -EINVAL;
445
446	line = gpiospec->args[0];
447	if (line >= chip->ngpio)
448		return -EINVAL;
449
450	timings = &fwd->delay_timings[line];
451	timings->ramp_up_us = gpiospec->args[1];
452	timings->ramp_down_us = gpiospec->args[2];
453
454	return line;
455}
456
457static int gpiochip_fwd_setup_delay_line(struct device *dev, struct gpio_chip *chip,
458					 struct gpiochip_fwd *fwd)
459{
460	fwd->delay_timings = devm_kcalloc(dev, chip->ngpio,
461					  sizeof(*fwd->delay_timings),
462					  GFP_KERNEL);
463	if (!fwd->delay_timings)
464		return -ENOMEM;
465
466	chip->of_xlate = gpiochip_fwd_delay_of_xlate;
467	chip->of_gpio_n_cells = 3;
468
469	return 0;
470}
471#else
472static int gpiochip_fwd_setup_delay_line(struct device *dev, struct gpio_chip *chip,
473					 struct gpiochip_fwd *fwd)
474{
475	return 0;
476}
477#endif	/* !CONFIG_OF_GPIO */
478
479/**
480 * gpiochip_fwd_create() - Create a new GPIO forwarder
481 * @dev: Parent device pointer
482 * @ngpios: Number of GPIOs in the forwarder.
483 * @descs: Array containing the GPIO descriptors to forward to.
484 *         This array must contain @ngpios entries, and must not be deallocated
485 *         before the forwarder has been destroyed again.
486 * @features: Bitwise ORed features as defined with FWD_FEATURE_*.
487 *
488 * This function creates a new gpiochip, which forwards all GPIO operations to
489 * the passed GPIO descriptors.
490 *
491 * Return: An opaque object pointer, or an ERR_PTR()-encoded negative error
492 *         code on failure.
493 */
494static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
495						unsigned int ngpios,
496						struct gpio_desc *descs[],
497						unsigned long features)
498{
499	const char *label = dev_name(dev);
500	struct gpiochip_fwd *fwd;
501	struct gpio_chip *chip;
502	unsigned int i;
503	int error;
504
505	fwd = devm_kzalloc(dev, struct_size(fwd, tmp, fwd_tmp_size(ngpios)),
506			   GFP_KERNEL);
507	if (!fwd)
508		return ERR_PTR(-ENOMEM);
509
510	chip = &fwd->chip;
511
512	/*
513	 * If any of the GPIO lines are sleeping, then the entire forwarder
514	 * will be sleeping.
515	 * If any of the chips support .set_config(), then the forwarder will
516	 * support setting configs.
517	 */
518	for (i = 0; i < ngpios; i++) {
519		struct gpio_chip *parent = gpiod_to_chip(descs[i]);
520
521		dev_dbg(dev, "%u => gpio %d irq %d\n", i,
522			desc_to_gpio(descs[i]), gpiod_to_irq(descs[i]));
523
524		if (gpiod_cansleep(descs[i]))
525			chip->can_sleep = true;
526		if (parent && parent->set_config)
527			chip->set_config = gpio_fwd_set_config;
528	}
529
530	chip->label = label;
531	chip->parent = dev;
532	chip->owner = THIS_MODULE;
533	chip->get_direction = gpio_fwd_get_direction;
534	chip->direction_input = gpio_fwd_direction_input;
535	chip->direction_output = gpio_fwd_direction_output;
536	chip->get = gpio_fwd_get;
537	chip->get_multiple = gpio_fwd_get_multiple_locked;
538	chip->set = gpio_fwd_set;
539	chip->set_multiple = gpio_fwd_set_multiple_locked;
540	chip->to_irq = gpio_fwd_to_irq;
541	chip->base = -1;
542	chip->ngpio = ngpios;
543	fwd->descs = descs;
544
545	if (chip->can_sleep)
546		mutex_init(&fwd->mlock);
547	else
548		spin_lock_init(&fwd->slock);
549
550	if (features & FWD_FEATURE_DELAY) {
551		error = gpiochip_fwd_setup_delay_line(dev, chip, fwd);
552		if (error)
553			return ERR_PTR(error);
554	}
555
556	error = devm_gpiochip_add_data(dev, chip, fwd);
557	if (error)
558		return ERR_PTR(error);
559
560	return fwd;
561}
562
563
564/*
565 *  GPIO Aggregator platform device
566 */
567
568static int gpio_aggregator_probe(struct platform_device *pdev)
569{
570	struct device *dev = &pdev->dev;
571	struct gpio_desc **descs;
572	struct gpiochip_fwd *fwd;
573	unsigned long features;
574	int i, n;
575
576	n = gpiod_count(dev, NULL);
577	if (n < 0)
578		return n;
579
580	descs = devm_kmalloc_array(dev, n, sizeof(*descs), GFP_KERNEL);
581	if (!descs)
582		return -ENOMEM;
583
584	for (i = 0; i < n; i++) {
585		descs[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
586		if (IS_ERR(descs[i]))
587			return PTR_ERR(descs[i]);
588	}
589
590	features = (uintptr_t)device_get_match_data(dev);
591	fwd = gpiochip_fwd_create(dev, n, descs, features);
592	if (IS_ERR(fwd))
593		return PTR_ERR(fwd);
594
595	platform_set_drvdata(pdev, fwd);
596	return 0;
597}
598
599static const struct of_device_id gpio_aggregator_dt_ids[] = {
600	{
601		.compatible = "gpio-delay",
602		.data = (void *)FWD_FEATURE_DELAY,
603	},
604	/*
605	 * Add GPIO-operated devices controlled from userspace below,
606	 * or use "driver_override" in sysfs.
607	 */
608	{}
609};
610MODULE_DEVICE_TABLE(of, gpio_aggregator_dt_ids);
611
612static struct platform_driver gpio_aggregator_driver = {
613	.probe = gpio_aggregator_probe,
614	.driver = {
615		.name = DRV_NAME,
616		.groups = gpio_aggregator_groups,
617		.of_match_table = gpio_aggregator_dt_ids,
618	},
619};
620
621static int __init gpio_aggregator_init(void)
622{
623	return platform_driver_register(&gpio_aggregator_driver);
624}
625module_init(gpio_aggregator_init);
626
627static void __exit gpio_aggregator_exit(void)
628{
629	gpio_aggregator_remove_all();
630	platform_driver_unregister(&gpio_aggregator_driver);
631}
632module_exit(gpio_aggregator_exit);
633
634MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
635MODULE_DESCRIPTION("GPIO Aggregator");
636MODULE_LICENSE("GPL v2");
637