xref: /linux/drivers/gpio/gpio-mockup.c (revision 02680c23d7b3febe45ea3d4f9818c2b2dc89020a) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * GPIO Testing Device Driver
4  *
5  * Copyright (C) 2014  Kamlakant Patel <kamlakant.patel@broadcom.com>
6  * Copyright (C) 2015-2016  Bamvor Jian Zhang <bamv2005@gmail.com>
7  * Copyright (C) 2017 Bartosz Golaszewski <brgl@bgdev.pl>
8  */
9 
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 
12 #include <linux/debugfs.h>
13 #include <linux/gpio/driver.h>
14 #include <linux/interrupt.h>
15 #include <linux/irq.h>
16 #include <linux/irq_sim.h>
17 #include <linux/irqdomain.h>
18 #include <linux/mod_devicetable.h>
19 #include <linux/module.h>
20 #include <linux/platform_device.h>
21 #include <linux/property.h>
22 #include <linux/slab.h>
23 #include <linux/string_helpers.h>
24 #include <linux/uaccess.h>
25 
26 #include "gpiolib.h"
27 
28 #define GPIO_MOCKUP_MAX_GC	10
29 /*
30  * We're storing two values per chip: the GPIO base and the number
31  * of GPIO lines.
32  */
33 #define GPIO_MOCKUP_MAX_RANGES	(GPIO_MOCKUP_MAX_GC * 2)
34 /* Maximum of four properties + the sentinel. */
35 #define GPIO_MOCKUP_MAX_PROP	5
36 
37 /*
38  * struct gpio_pin_status - structure describing a GPIO status
39  * @dir:       Configures direction of gpio as "in" or "out"
40  * @value:     Configures status of the gpio as 0(low) or 1(high)
41  */
42 struct gpio_mockup_line_status {
43 	int dir;
44 	int value;
45 	int pull;
46 };
47 
48 struct gpio_mockup_chip {
49 	struct gpio_chip gc;
50 	struct gpio_mockup_line_status *lines;
51 	struct irq_domain *irq_sim_domain;
52 	struct dentry *dbg_dir;
53 	struct mutex lock;
54 };
55 
56 struct gpio_mockup_dbgfs_private {
57 	struct gpio_mockup_chip *chip;
58 	struct gpio_desc *desc;
59 	unsigned int offset;
60 };
61 
62 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
63 static int gpio_mockup_num_ranges;
64 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
65 
66 static bool gpio_mockup_named_lines;
67 module_param_named(gpio_mockup_named_lines,
68 		   gpio_mockup_named_lines, bool, 0400);
69 
70 static struct dentry *gpio_mockup_dbg_dir;
71 
72 static int gpio_mockup_range_base(unsigned int index)
73 {
74 	return gpio_mockup_ranges[index * 2];
75 }
76 
77 static int gpio_mockup_range_ngpio(unsigned int index)
78 {
79 	return gpio_mockup_ranges[index * 2 + 1];
80 }
81 
82 static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
83 			     unsigned int offset)
84 {
85 	return chip->lines[offset].value;
86 }
87 
88 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
89 {
90 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
91 	int val;
92 
93 	mutex_lock(&chip->lock);
94 	val = __gpio_mockup_get(chip, offset);
95 	mutex_unlock(&chip->lock);
96 
97 	return val;
98 }
99 
100 static int gpio_mockup_get_multiple(struct gpio_chip *gc,
101 				    unsigned long *mask, unsigned long *bits)
102 {
103 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
104 	unsigned int bit, val;
105 
106 	mutex_lock(&chip->lock);
107 	for_each_set_bit(bit, mask, gc->ngpio) {
108 		val = __gpio_mockup_get(chip, bit);
109 		__assign_bit(bit, bits, val);
110 	}
111 	mutex_unlock(&chip->lock);
112 
113 	return 0;
114 }
115 
116 static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
117 			      unsigned int offset, int value)
118 {
119 	chip->lines[offset].value = !!value;
120 }
121 
122 static void gpio_mockup_set(struct gpio_chip *gc,
123 			   unsigned int offset, int value)
124 {
125 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
126 
127 	mutex_lock(&chip->lock);
128 	__gpio_mockup_set(chip, offset, value);
129 	mutex_unlock(&chip->lock);
130 }
131 
132 static void gpio_mockup_set_multiple(struct gpio_chip *gc,
133 				     unsigned long *mask, unsigned long *bits)
134 {
135 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
136 	unsigned int bit;
137 
138 	mutex_lock(&chip->lock);
139 	for_each_set_bit(bit, mask, gc->ngpio)
140 		__gpio_mockup_set(chip, bit, test_bit(bit, bits));
141 	mutex_unlock(&chip->lock);
142 }
143 
144 static int gpio_mockup_apply_pull(struct gpio_mockup_chip *chip,
145 				  unsigned int offset, int value)
146 {
147 	int curr, irq, irq_type, ret = 0;
148 	struct gpio_desc *desc;
149 	struct gpio_chip *gc;
150 
151 	gc = &chip->gc;
152 	desc = &gc->gpiodev->descs[offset];
153 
154 	mutex_lock(&chip->lock);
155 
156 	if (test_bit(FLAG_REQUESTED, &desc->flags) &&
157 	    !test_bit(FLAG_IS_OUT, &desc->flags)) {
158 		curr = __gpio_mockup_get(chip, offset);
159 		if (curr == value)
160 			goto out;
161 
162 		irq = irq_find_mapping(chip->irq_sim_domain, offset);
163 		if (!irq)
164 			/*
165 			 * This is fine - it just means, nobody is listening
166 			 * for interrupts on this line, otherwise
167 			 * irq_create_mapping() would have been called from
168 			 * the to_irq() callback.
169 			 */
170 			goto set_value;
171 
172 		irq_type = irq_get_trigger_type(irq);
173 
174 		if ((value == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
175 		    (value == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING))) {
176 			ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING,
177 						    true);
178 			if (ret)
179 				goto out;
180 		}
181 	}
182 
183 set_value:
184 	/* Change the value unless we're actively driving the line. */
185 	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
186 	    !test_bit(FLAG_IS_OUT, &desc->flags))
187 		__gpio_mockup_set(chip, offset, value);
188 
189 out:
190 	chip->lines[offset].pull = value;
191 	mutex_unlock(&chip->lock);
192 	return ret;
193 }
194 
195 static int gpio_mockup_set_config(struct gpio_chip *gc,
196 				  unsigned int offset, unsigned long config)
197 {
198 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
199 
200 	switch (pinconf_to_config_param(config)) {
201 	case PIN_CONFIG_BIAS_PULL_UP:
202 		return gpio_mockup_apply_pull(chip, offset, 1);
203 	case PIN_CONFIG_BIAS_PULL_DOWN:
204 		return gpio_mockup_apply_pull(chip, offset, 0);
205 	default:
206 		break;
207 	}
208 	return -ENOTSUPP;
209 }
210 
211 static int gpio_mockup_dirout(struct gpio_chip *gc,
212 			      unsigned int offset, int value)
213 {
214 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
215 
216 	mutex_lock(&chip->lock);
217 	chip->lines[offset].dir = GPIO_LINE_DIRECTION_OUT;
218 	__gpio_mockup_set(chip, offset, value);
219 	mutex_unlock(&chip->lock);
220 
221 	return 0;
222 }
223 
224 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
225 {
226 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
227 
228 	mutex_lock(&chip->lock);
229 	chip->lines[offset].dir = GPIO_LINE_DIRECTION_IN;
230 	mutex_unlock(&chip->lock);
231 
232 	return 0;
233 }
234 
235 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
236 {
237 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
238 	int direction;
239 
240 	mutex_lock(&chip->lock);
241 	direction = chip->lines[offset].dir;
242 	mutex_unlock(&chip->lock);
243 
244 	return direction;
245 }
246 
247 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
248 {
249 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
250 
251 	return irq_create_mapping(chip->irq_sim_domain, offset);
252 }
253 
254 static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
255 {
256 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
257 
258 	__gpio_mockup_set(chip, offset, chip->lines[offset].pull);
259 }
260 
261 static ssize_t gpio_mockup_debugfs_read(struct file *file,
262 					char __user *usr_buf,
263 					size_t size, loff_t *ppos)
264 {
265 	struct gpio_mockup_dbgfs_private *priv;
266 	struct gpio_mockup_chip *chip;
267 	struct seq_file *sfile;
268 	struct gpio_chip *gc;
269 	int val, cnt;
270 	char buf[3];
271 
272 	if (*ppos != 0)
273 		return 0;
274 
275 	sfile = file->private_data;
276 	priv = sfile->private;
277 	chip = priv->chip;
278 	gc = &chip->gc;
279 
280 	val = gpio_mockup_get(gc, priv->offset);
281 	cnt = snprintf(buf, sizeof(buf), "%d\n", val);
282 
283 	return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt);
284 }
285 
286 static ssize_t gpio_mockup_debugfs_write(struct file *file,
287 					 const char __user *usr_buf,
288 					 size_t size, loff_t *ppos)
289 {
290 	struct gpio_mockup_dbgfs_private *priv;
291 	int rv, val;
292 	struct seq_file *sfile;
293 
294 	if (*ppos != 0)
295 		return -EINVAL;
296 
297 	rv = kstrtoint_from_user(usr_buf, size, 0, &val);
298 	if (rv)
299 		return rv;
300 	if (val != 0 && val != 1)
301 		return -EINVAL;
302 
303 	sfile = file->private_data;
304 	priv = sfile->private;
305 	rv = gpio_mockup_apply_pull(priv->chip, priv->offset, val);
306 	if (rv)
307 		return rv;
308 
309 	return size;
310 }
311 
312 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
313 {
314 	return single_open(file, NULL, inode->i_private);
315 }
316 
317 /*
318  * Each mockup chip is represented by a directory named after the chip's device
319  * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
320  * a file using the line's offset as the name under the chip's directory.
321  *
322  * Reading from the line's file yields the current *value*, writing to the
323  * line's file changes the current *pull*. Default pull for mockup lines is
324  * down.
325  *
326  * Examples:
327  * - when a line pulled down is requested in output mode and driven high, its
328  *   value will return to 0 once it's released
329  * - when the line is requested in output mode and driven high, writing 0 to
330  *   the corresponding debugfs file will change the pull to down but the
331  *   reported value will still be 1 until the line is released
332  * - line requested in input mode always reports the same value as its pull
333  *   configuration
334  * - when the line is requested in input mode and monitored for events, writing
335  *   the same value to the debugfs file will be a noop, while writing the
336  *   opposite value will generate a dummy interrupt with an appropriate edge
337  */
338 static const struct file_operations gpio_mockup_debugfs_ops = {
339 	.owner = THIS_MODULE,
340 	.open = gpio_mockup_debugfs_open,
341 	.read = gpio_mockup_debugfs_read,
342 	.write = gpio_mockup_debugfs_write,
343 	.llseek = no_llseek,
344 	.release = single_release,
345 };
346 
347 static void gpio_mockup_debugfs_setup(struct device *dev,
348 				      struct gpio_mockup_chip *chip)
349 {
350 	struct gpio_mockup_dbgfs_private *priv;
351 	struct gpio_chip *gc;
352 	const char *devname;
353 	char *name;
354 	int i;
355 
356 	gc = &chip->gc;
357 	devname = dev_name(&gc->gpiodev->dev);
358 
359 	chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
360 
361 	for (i = 0; i < gc->ngpio; i++) {
362 		name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
363 		if (!name)
364 			return;
365 
366 		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
367 		if (!priv)
368 			return;
369 
370 		priv->chip = chip;
371 		priv->offset = i;
372 		priv->desc = &gc->gpiodev->descs[i];
373 
374 		debugfs_create_file(name, 0200, chip->dbg_dir, priv,
375 				    &gpio_mockup_debugfs_ops);
376 	}
377 }
378 
379 static void gpio_mockup_dispose_mappings(void *data)
380 {
381 	struct gpio_mockup_chip *chip = data;
382 	struct gpio_chip *gc = &chip->gc;
383 	int i, irq;
384 
385 	for (i = 0; i < gc->ngpio; i++) {
386 		irq = irq_find_mapping(chip->irq_sim_domain, i);
387 		if (irq)
388 			irq_dispose_mapping(irq);
389 	}
390 }
391 
392 static int gpio_mockup_probe(struct platform_device *pdev)
393 {
394 	struct gpio_mockup_chip *chip;
395 	struct gpio_chip *gc;
396 	struct device *dev;
397 	const char *name;
398 	int rv, base, i;
399 	u16 ngpio;
400 
401 	dev = &pdev->dev;
402 
403 	rv = device_property_read_u32(dev, "gpio-base", &base);
404 	if (rv)
405 		base = -1;
406 
407 	rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
408 	if (rv)
409 		return rv;
410 
411 	rv = device_property_read_string(dev, "chip-label", &name);
412 	if (rv)
413 		name = dev_name(dev);
414 
415 	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
416 	if (!chip)
417 		return -ENOMEM;
418 
419 	mutex_init(&chip->lock);
420 
421 	gc = &chip->gc;
422 	gc->base = base;
423 	gc->ngpio = ngpio;
424 	gc->label = name;
425 	gc->owner = THIS_MODULE;
426 	gc->parent = dev;
427 	gc->get = gpio_mockup_get;
428 	gc->set = gpio_mockup_set;
429 	gc->get_multiple = gpio_mockup_get_multiple;
430 	gc->set_multiple = gpio_mockup_set_multiple;
431 	gc->direction_output = gpio_mockup_dirout;
432 	gc->direction_input = gpio_mockup_dirin;
433 	gc->get_direction = gpio_mockup_get_direction;
434 	gc->set_config = gpio_mockup_set_config;
435 	gc->to_irq = gpio_mockup_to_irq;
436 	gc->free = gpio_mockup_free;
437 
438 	chip->lines = devm_kcalloc(dev, gc->ngpio,
439 				   sizeof(*chip->lines), GFP_KERNEL);
440 	if (!chip->lines)
441 		return -ENOMEM;
442 
443 	for (i = 0; i < gc->ngpio; i++)
444 		chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
445 
446 	chip->irq_sim_domain = devm_irq_domain_create_sim(dev, NULL,
447 							  gc->ngpio);
448 	if (IS_ERR(chip->irq_sim_domain))
449 		return PTR_ERR(chip->irq_sim_domain);
450 
451 	rv = devm_add_action_or_reset(dev, gpio_mockup_dispose_mappings, chip);
452 	if (rv)
453 		return rv;
454 
455 	rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
456 	if (rv)
457 		return rv;
458 
459 	gpio_mockup_debugfs_setup(dev, chip);
460 
461 	return 0;
462 }
463 
464 static const struct of_device_id gpio_mockup_of_match[] = {
465 	{ .compatible = "gpio-mockup", },
466 	{},
467 };
468 MODULE_DEVICE_TABLE(of, gpio_mockup_of_match);
469 
470 static struct platform_driver gpio_mockup_driver = {
471 	.driver = {
472 		.name = "gpio-mockup",
473 		.of_match_table = gpio_mockup_of_match,
474 	},
475 	.probe = gpio_mockup_probe,
476 };
477 
478 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
479 
480 static void gpio_mockup_unregister_pdevs(void)
481 {
482 	int i;
483 
484 	for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++)
485 		platform_device_unregister(gpio_mockup_pdevs[i]);
486 }
487 
488 static __init char **gpio_mockup_make_line_names(const char *label,
489 						 unsigned int num_lines)
490 {
491 	unsigned int i;
492 	char **names;
493 
494 	names = kcalloc(num_lines + 1, sizeof(char *), GFP_KERNEL);
495 	if (!names)
496 		return NULL;
497 
498 	for (i = 0; i < num_lines; i++) {
499 		names[i] = kasprintf(GFP_KERNEL, "%s-%u", label, i);
500 		if (!names[i]) {
501 			kfree_strarray(names, i);
502 			return NULL;
503 		}
504 	}
505 
506 	return names;
507 }
508 
509 static int __init gpio_mockup_register_chip(int idx)
510 {
511 	struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
512 	struct platform_device_info pdevinfo;
513 	struct platform_device *pdev;
514 	char **line_names = NULL;
515 	char chip_label[32];
516 	int prop = 0, base;
517 	u16 ngpio;
518 
519 	memset(properties, 0, sizeof(properties));
520 	memset(&pdevinfo, 0, sizeof(pdevinfo));
521 
522 	snprintf(chip_label, sizeof(chip_label), "gpio-mockup-%c", idx + 'A');
523 	properties[prop++] = PROPERTY_ENTRY_STRING("chip-label", chip_label);
524 
525 	base = gpio_mockup_range_base(idx);
526 	if (base >= 0)
527 		properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", base);
528 
529 	ngpio = base < 0 ? gpio_mockup_range_ngpio(idx)
530 			 : gpio_mockup_range_ngpio(idx) - base;
531 	properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
532 
533 	if (gpio_mockup_named_lines) {
534 		line_names = gpio_mockup_make_line_names(chip_label, ngpio);
535 		if (!line_names)
536 			return -ENOMEM;
537 
538 		properties[prop++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
539 					"gpio-line-names", line_names, ngpio);
540 	}
541 
542 	pdevinfo.name = "gpio-mockup";
543 	pdevinfo.id = idx;
544 	pdevinfo.properties = properties;
545 
546 	pdev = platform_device_register_full(&pdevinfo);
547 	kfree_strarray(line_names, ngpio);
548 	if (IS_ERR(pdev)) {
549 		pr_err("error registering device");
550 		return PTR_ERR(pdev);
551 	}
552 
553 	gpio_mockup_pdevs[idx] = pdev;
554 
555 	return 0;
556 }
557 
558 static int __init gpio_mockup_init(void)
559 {
560 	int i, num_chips, err;
561 
562 	if ((gpio_mockup_num_ranges % 2) ||
563 	    (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
564 		return -EINVAL;
565 
566 	/* Each chip is described by two values. */
567 	num_chips = gpio_mockup_num_ranges / 2;
568 
569 	/*
570 	 * The second value in the <base GPIO - number of GPIOS> pair must
571 	 * always be greater than 0.
572 	 */
573 	for (i = 0; i < num_chips; i++) {
574 		if (gpio_mockup_range_ngpio(i) < 0)
575 			return -EINVAL;
576 	}
577 
578 	gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
579 
580 	err = platform_driver_register(&gpio_mockup_driver);
581 	if (err) {
582 		pr_err("error registering platform driver\n");
583 		debugfs_remove_recursive(gpio_mockup_dbg_dir);
584 		return err;
585 	}
586 
587 	for (i = 0; i < num_chips; i++) {
588 		err = gpio_mockup_register_chip(i);
589 		if (err) {
590 			platform_driver_unregister(&gpio_mockup_driver);
591 			gpio_mockup_unregister_pdevs();
592 			debugfs_remove_recursive(gpio_mockup_dbg_dir);
593 			return err;
594 		}
595 	}
596 
597 	return 0;
598 }
599 
600 static void __exit gpio_mockup_exit(void)
601 {
602 	debugfs_remove_recursive(gpio_mockup_dbg_dir);
603 	platform_driver_unregister(&gpio_mockup_driver);
604 	gpio_mockup_unregister_pdevs();
605 }
606 
607 module_init(gpio_mockup_init);
608 module_exit(gpio_mockup_exit);
609 
610 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
611 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
612 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
613 MODULE_DESCRIPTION("GPIO Testing driver");
614 MODULE_LICENSE("GPL v2");
615