summaryrefslogtreecommitdiffstats
path: root/drivers/gpio/gpio-mockup.c
blob: 455eecf6380e4422156786516d64c13e4c08933d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * GPIO Testing Device Driver
 *
 * Copyright (C) 2014  Kamlakant Patel <kamlakant.patel@broadcom.com>
 * Copyright (C) 2015-2016  Bamvor Jian Zhang <bamv2005@gmail.com>
 * Copyright (C) 2017 Bartosz Golaszewski <brgl@bgdev.pl>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/cleanup.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/gpio/driver.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irq_sim.h>
#include <linux/irqdomain.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string_helpers.h>
#include <linux/uaccess.h>

#define GPIO_MOCKUP_MAX_GC	10
/*
 * We're storing two values per chip: the GPIO base and the number
 * of GPIO lines.
 */
#define GPIO_MOCKUP_MAX_RANGES	(GPIO_MOCKUP_MAX_GC * 2)
/* Maximum of four properties + the sentinel. */
#define GPIO_MOCKUP_MAX_PROP	5

/*
 * struct gpio_pin_status - structure describing a GPIO status
 * @dir:       Configures direction of gpio as "in" or "out"
 * @value:     Configures status of the gpio as 0(low) or 1(high)
 * @pull:      Configures the current pull of the GPIO as 0 (pull-down) or
 *             1 (pull-up)
 * @requested: Request status of this GPIO
 */
struct gpio_mockup_line_status {
	int dir;
	int value;
	int pull;
	bool requested;
};

struct gpio_mockup_chip {
	struct gpio_chip gc;
	struct gpio_mockup_line_status *lines;
	struct irq_domain *irq_sim_domain;
	struct dentry *dbg_dir;
	struct mutex lock;
};

struct gpio_mockup_dbgfs_private {
	struct gpio_mockup_chip *chip;
	unsigned int offset;
};

static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
static int gpio_mockup_num_ranges;
module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);

static bool gpio_mockup_named_lines;
module_param_named(gpio_mockup_named_lines,
		   gpio_mockup_named_lines, bool, 0400);

static struct dentry *gpio_mockup_dbg_dir;

static int gpio_mockup_range_base(unsigned int index)
{
	return gpio_mockup_ranges[index * 2];
}

static int gpio_mockup_range_ngpio(unsigned int index)
{
	return gpio_mockup_ranges[index * 2 + 1];
}

static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
			     unsigned int offset)
{
	return chip->lines[offset].value;
}

static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
{
	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
	int val;

	scoped_guard(mutex, &chip->lock)
		val = __gpio_mockup_get(chip, offset);

	return val;
}

static int gpio_mockup_get_multiple(struct gpio_chip *gc,
				    unsigned long *mask, unsigned long *bits)
{
	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
	unsigned int bit, val;

	scoped_guard(mutex, &chip->lock) {
		for_each_set_bit(bit, mask, gc->ngpio) {
			val = __gpio_mockup_get(chip, bit);
			__assign_bit(bit, bits, val);
		}
	}

	return 0;
}

static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
			      unsigned int offset, int value)
{
	chip->lines[offset].value = !!value;
}

static void gpio_mockup_set(struct gpio_chip *gc,
			   unsigned int offset, int value)
{
	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);

	guard(mutex)(&chip->lock);

	__gpio_mockup_set(chip, offset, value);
}

static void gpio_mockup_set_multiple(struct gpio_chip *gc,
				     unsigned long *mask, unsigned long *bits)
{
	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
	unsigned int bit;

	guard(mutex)(&chip->lock);

	for_each_set_bit(bit, mask, gc->ngpio)
		__gpio_mockup_set(chip, bit, test_bit(bit, bits));
}

static int gpio_mockup_apply_pull(struct gpio_mockup_chip *chip,
				  unsigned int offset, int value)
{
	struct gpio_mockup_line_status *line = &chip->lines[offset];
	int curr, irq, irq_type, ret = 0;

	guard(mutex)(&chip->lock);

	if (line->requested && line->dir == GPIO_LINE_DIRECTION_IN) {
		curr = __gpio_mockup_get(chip, offset);
		if (curr == value)
			goto out;

		irq = irq_find_mapping(chip->irq_sim_domain, offset);
		if (!irq)
			/*
			 * This is fine - it just means, nobody is listening
			 * for interrupts on this line, otherwise
			 * irq_create_mapping() would have been called from
			 * the to_irq() callback.
			 */
			goto set_value;

		irq_type = irq_get_trigger_type(irq);

		if ((value == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
		    (value == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING))) {
			ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING,
						    true);
			if (ret)
				goto out;
		}
	}

set_value:
	/* Change the value unless we're actively driving the line. */
	if (!line->requested || line->dir == GPIO_LINE_DIRECTION_IN)
		__gpio_mockup_set(chip, offset, value);

out:
	chip->lines[offset].pull = value;
	return ret;
}

static int gpio_mockup_set_config(struct gpio_chip *gc,
				  unsigned int offset, unsigned long config)
{
	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);

	switch (pinconf_to_config_param(config)) {
	case PIN_CONFIG_BIAS_PULL_UP:
		return gpio_mockup_apply_pull(chip, offset, 1);
	case PIN_CONFIG_BIAS_PULL_DOWN:
		return gpio_mockup_apply_pull(chip, offset, 0);
	default:
		break;
	}
	return -ENOTSUPP;
}

static int gpio_mockup_dirout(struct gpio_chip *gc,
			      unsigned int offset, int value)
{
	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);

	scoped_guard(mutex, &chip->lock) {
		chip->lines[offset].dir = GPIO_LINE_DIRECTION_OUT;
		__gpio_mockup_set(chip, offset, value);
	}

	return 0;
}

static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
{
	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);

	scoped_guard(mutex, &chip->lock)
		chip->lines[offset].dir = GPIO_LINE_DIRECTION_IN;

	return 0;
}

static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
{
	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
	int direction;

	scoped_guard(mutex, &chip->lock)
		direction = chip->lines[offset].dir;

	return direction;
}

static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
{
	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);

	return irq_create_mapping(chip->irq_sim_domain, offset);
}

static int gpio_mockup_request(struct gpio_chip *gc, unsigned int offset)
{
	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);

	scoped_guard(mutex, &chip->lock)
		chip->lines[offset].requested = true;

	return 0;
}

static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
{
	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);

	guard(mutex)(&chip->lock);

	chip->lines[offset].requested = false;
	__gpio_mockup_set(chip, offset, chip->lines[offset].pull);
}

static ssize_t gpio_mockup_debugfs_read(struct file *file,
					char __user *usr_buf,
					size_t size, loff_t *ppos)
{
	struct gpio_mockup_dbgfs_private *priv;
	struct gpio_mockup_chip *chip;
	struct seq_file *sfile;
	struct gpio_chip *gc;
	int val, cnt;
	char buf[3];

	if (*ppos != 0)
		return 0;

	sfile = file->private_data;
	priv = sfile->private;
	chip = priv->chip;
	gc = &chip->gc;

	val = gpio_mockup_get(gc, priv->offset);
	cnt = snprintf(buf, sizeof(buf), "%d\n", val);

	return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt);
}

static ssize_t gpio_mockup_debugfs_write(struct file *file,
					 const char __user *usr_buf,
					 size_t size, loff_t *ppos)
{
	struct gpio_mockup_dbgfs_private *priv;
	int rv, val;
	struct seq_file *sfile;

	if (*ppos != 0)
		return -EINVAL;

	rv = kstrtoint_from_user(usr_buf, size, 0, &val);
	if (rv)
		return rv;
	if (val != 0 && val != 1)
		return -EINVAL;

	sfile = file->private_data;
	priv = sfile->private;
	rv = gpio_mockup_apply_pull(priv->chip, priv->offset, val);
	if (rv)
		return rv;

	return size;
}

static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
{
	return single_open(file, NULL, inode->i_private);
}

/*
 * Each mockup chip is represented by a directory named after the chip's device
 * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
 * a file using the line's offset as the name under the chip's directory.
 *
 * Reading from the line's file yields the current *value*, writing to the
 * line's file changes the current *pull*. Default pull for mockup lines is
 * down.
 *
 * Examples:
 * - when a line pulled down is requested in output mode and driven high, its
 *   value will return to 0 once it's released
 * - when the line is requested in output mode and driven high, writing 0 to
 *   the corresponding debugfs file will change the pull to down but the
 *   reported value will still be 1 until the line is released
 * - line requested in input mode always reports the same value as its pull
 *   configuration
 * - when the line is requested in input mode and monitored for events, writing
 *   the same value to the debugfs file will be a noop, while writing the
 *   opposite value will generate a dummy interrupt with an appropriate edge
 */
static const struct file_operations gpio_mockup_debugfs_ops = {
	.owner = THIS_MODULE,
	.open = gpio_mockup_debugfs_open,
	.read = gpio_mockup_debugfs_read,
	.write = gpio_mockup_debugfs_write,
	.llseek = no_llseek,
	.release = single_release,
};

static void gpio_mockup_debugfs_setup(struct device *dev,
				      struct gpio_mockup_chip *chip)
{
	struct gpio_mockup_dbgfs_private *priv;
	struct gpio_chip *gc;
	const char *devname;
	char *name;
	int i;

	gc = &chip->gc;

	/*
	 * There can only be a single GPIO device per platform device in
	 * gpio-mockup so using device_find_any_child() is OK.
	 */
	struct device *child __free(put_device) = device_find_any_child(dev);
	if (!child)
		return;

	devname = dev_name(child);
	chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);

	for (i = 0; i < gc->ngpio; i++) {
		name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
		if (!name)
			return;

		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
		if (!priv)
			return;

		priv->chip = chip;
		priv->offset = i;

		debugfs_create_file(name, 0600, chip->dbg_dir, priv,
				    &gpio_mockup_debugfs_ops);
	}
}

static void gpio_mockup_debugfs_cleanup(void *data)
{
	struct gpio_mockup_chip *chip = data;

	debugfs_remove_recursive(chip->dbg_dir);
}

static void gpio_mockup_dispose_mappings(void *data)
{
	struct gpio_mockup_chip *chip = data;
	struct gpio_chip *gc = &chip->gc;
	int i, irq;

	for (i = 0; i < gc->ngpio; i++) {
		irq = irq_find_mapping(chip->irq_sim_domain, i);
		if (irq)
			irq_dispose_mapping(irq);
	}
}

static int gpio_mockup_probe(struct platform_device *pdev)
{
	struct gpio_mockup_chip *chip;
	struct gpio_chip *gc;
	struct device *dev;
	const char *name;
	int rv, base, i;
	u16 ngpio;

	dev = &pdev->dev;

	rv = device_property_read_u32(dev, "gpio-base", &base);
	if (rv)
		base = -1;

	rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
	if (rv)
		return rv;

	rv = device_property_read_string(dev, "chip-label", &name);
	if (rv)
		name = dev_name(dev);

	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
	if (!chip)
		return -ENOMEM;

	mutex_init(&chip->lock);

	gc = &chip->gc;
	gc->base = base;
	gc->ngpio = ngpio;
	gc->label = name;
	gc->owner = THIS_MODULE;
	gc->parent = dev;
	gc->get = gpio_mockup_get;
	gc->set = gpio_mockup_set;
	gc->get_multiple = gpio_mockup_get_multiple;
	gc->set_multiple = gpio_mockup_set_multiple;
	gc->direction_output = gpio_mockup_dirout;
	gc->direction_input = gpio_mockup_dirin;
	gc->get_direction = gpio_mockup_get_direction;
	gc->set_config = gpio_mockup_set_config;
	gc->to_irq = gpio_mockup_to_irq;
	gc->request = gpio_mockup_request;
	gc->free = gpio_mockup_free;

	chip->lines = devm_kcalloc(dev, gc->ngpio,
				   sizeof(*chip->lines), GFP_KERNEL);
	if (!chip->lines)
		return -ENOMEM;

	for (i = 0; i < gc->ngpio; i++)
		chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;

	chip->irq_sim_domain = devm_irq_domain_create_sim(dev, NULL,
							  gc->ngpio);
	if (IS_ERR(chip->irq_sim_domain))
		return PTR_ERR(chip->irq_sim_domain);

	rv = devm_add_action_or_reset(dev, gpio_mockup_dispose_mappings, chip);
	if (rv)
		return rv;

	rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
	if (rv)
		return rv;

	gpio_mockup_debugfs_setup(dev, chip);

	return devm_add_action_or_reset(dev, gpio_mockup_debugfs_cleanup, chip);
}

static const struct of_device_id gpio_mockup_of_match[] = {
	{ .compatible = "gpio-mockup", },
	{},
};
MODULE_DEVICE_TABLE(of, gpio_mockup_of_match);

static struct platform_driver gpio_mockup_driver = {
	.driver = {
		.name = "gpio-mockup",
		.of_match_table = gpio_mockup_of_match,
	},
	.probe = gpio_mockup_probe,
};

static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];

static void gpio_mockup_unregister_pdevs(void)
{
	struct platform_device *pdev;
	struct fwnode_handle *fwnode;
	int i;

	for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
		pdev = gpio_mockup_pdevs[i];
		if (!pdev)
			continue;

		fwnode = dev_fwnode(&pdev->dev);
		platform_device_unregister(pdev);
		fwnode_remove_software_node(fwnode);
	}
}

static int __init gpio_mockup_register_chip(int idx)
{
	struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
	struct platform_device_info pdevinfo;
	struct platform_device *pdev;
	struct fwnode_handle *fwnode;
	char **line_names = NULL;
	char chip_label[32];
	int prop = 0, base;
	u16 ngpio;

	memset(properties, 0, sizeof(properties));
	memset(&pdevinfo, 0, sizeof(pdevinfo));

	snprintf(chip_label, sizeof(chip_label), "gpio-mockup-%c", idx + 'A');
	properties[prop++] = PROPERTY_ENTRY_STRING("chip-label", chip_label);

	base = gpio_mockup_range_base(idx);
	if (base >= 0)
		properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", base);

	ngpio = base < 0 ? gpio_mockup_range_ngpio(idx)
			 : gpio_mockup_range_ngpio(idx) - base;
	properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);

	if (gpio_mockup_named_lines) {
		line_names = kasprintf_strarray(GFP_KERNEL, chip_label, ngpio);
		if (!line_names)
			return -ENOMEM;

		properties[prop++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
					"gpio-line-names", line_names, ngpio);
	}

	fwnode = fwnode_create_software_node(properties, NULL);
	if (IS_ERR(fwnode)) {
		kfree_strarray(line_names, ngpio);
		return PTR_ERR(fwnode);
	}

	pdevinfo.name = "gpio-mockup";
	pdevinfo.id = idx;
	pdevinfo.fwnode = fwnode;

	pdev = platform_device_register_full(&pdevinfo);
	kfree_strarray(line_names, ngpio);
	if (IS_ERR(pdev)) {
		fwnode_remove_software_node(fwnode);
		pr_err("error registering device");
		return PTR_ERR(pdev);
	}

	gpio_mockup_pdevs[idx] = pdev;

	return 0;
}

static int __init gpio_mockup_init(void)
{
	int i, num_chips, err;

	if ((gpio_mockup_num_ranges % 2) ||
	    (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
		return -EINVAL;

	/* Each chip is described by two values. */
	num_chips = gpio_mockup_num_ranges / 2;

	/*
	 * The second value in the <base GPIO - number of GPIOS> pair must
	 * always be greater than 0.
	 */
	for (i = 0; i < num_chips; i++) {
		if (gpio_mockup_range_ngpio(i) < 0)
			return -EINVAL;
	}

	gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);

	err = platform_driver_register(&gpio_mockup_driver);
	if (err) {
		pr_err("error registering platform driver\n");
		debugfs_remove_recursive(gpio_mockup_dbg_dir);
		return err;
	}

	for (i = 0; i < num_chips; i++) {
		err = gpio_mockup_register_chip(i);
		if (err) {
			platform_driver_unregister(&gpio_mockup_driver);
			gpio_mockup_unregister_pdevs();
			debugfs_remove_recursive(gpio_mockup_dbg_dir);
			return err;
		}
	}

	return 0;
}

static void __exit gpio_mockup_exit(void)
{
	gpio_mockup_unregister_pdevs();
	debugfs_remove_recursive(gpio_mockup_dbg_dir);
	platform_driver_unregister(&gpio_mockup_driver);
}

module_init(gpio_mockup_init);
module_exit(gpio_mockup_exit);

MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
MODULE_DESCRIPTION("GPIO Testing driver");
MODULE_LICENSE("GPL v2");