xref: /linux/drivers/gpio/gpio-mockup.c (revision 1b0975ee3bdd3eb19a47371c26fd7ef8f7f6b599) 
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/seq_file.h>
23 #include <linux/slab.h>
24 #include <linux/string_helpers.h>
25 #include <linux/uaccess.h>
26 
27 #include "gpiolib.h"
28 
29 #define GPIO_MOCKUP_MAX_GC	10
30 /*
31  * We're storing two values per chip: the GPIO base and the number
32  * of GPIO lines.
33  */
34 #define GPIO_MOCKUP_MAX_RANGES	(GPIO_MOCKUP_MAX_GC * 2)
35 /* Maximum of four properties + the sentinel. */
36 #define GPIO_MOCKUP_MAX_PROP	5
37 
38 /*
39  * struct gpio_pin_status - structure describing a GPIO status
40  * @dir:       Configures direction of gpio as "in" or "out"
41  * @value:     Configures status of the gpio as 0(low) or 1(high)
42  */
43 struct gpio_mockup_line_status {
44 	int dir;
45 	int value;
46 	int pull;
47 };
48 
49 struct gpio_mockup_chip {
50 	struct gpio_chip gc;
51 	struct gpio_mockup_line_status *lines;
52 	struct irq_domain *irq_sim_domain;
53 	struct dentry *dbg_dir;
54 	struct mutex lock;
55 };
56 
57 struct gpio_mockup_dbgfs_private {
58 	struct gpio_mockup_chip *chip;
59 	struct gpio_desc *desc;
60 	unsigned int offset;
61 };
62 
63 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
64 static int gpio_mockup_num_ranges;
65 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
66 
67 static bool gpio_mockup_named_lines;
68 module_param_named(gpio_mockup_named_lines,
69 		   gpio_mockup_named_lines, bool, 0400);
70 
71 static struct dentry *gpio_mockup_dbg_dir;
72 
73 static int gpio_mockup_range_base(unsigned int index)
74 {
75 	return gpio_mockup_ranges[index * 2];
76 }
77 
78 static int gpio_mockup_range_ngpio(unsigned int index)
79 {
80 	return gpio_mockup_ranges[index * 2 + 1];
81 }
82 
83 static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
84 			     unsigned int offset)
85 {
86 	return chip->lines[offset].value;
87 }
88 
89 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
90 {
91 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
92 	int val;
93 
94 	mutex_lock(&chip->lock);
95 	val = __gpio_mockup_get(chip, offset);
96 	mutex_unlock(&chip->lock);
97 
98 	return val;
99 }
100 
101 static int gpio_mockup_get_multiple(struct gpio_chip *gc,
102 				    unsigned long *mask, unsigned long *bits)
103 {
104 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
105 	unsigned int bit, val;
106 
107 	mutex_lock(&chip->lock);
108 	for_each_set_bit(bit, mask, gc->ngpio) {
109 		val = __gpio_mockup_get(chip, bit);
110 		__assign_bit(bit, bits, val);
111 	}
112 	mutex_unlock(&chip->lock);
113 
114 	return 0;
115 }
116 
117 static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
118 			      unsigned int offset, int value)
119 {
120 	chip->lines[offset].value = !!value;
121 }
122 
123 static void gpio_mockup_set(struct gpio_chip *gc,
124 			   unsigned int offset, int value)
125 {
126 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
127 
128 	mutex_lock(&chip->lock);
129 	__gpio_mockup_set(chip, offset, value);
130 	mutex_unlock(&chip->lock);
131 }
132 
133 static void gpio_mockup_set_multiple(struct gpio_chip *gc,
134 				     unsigned long *mask, unsigned long *bits)
135 {
136 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
137 	unsigned int bit;
138 
139 	mutex_lock(&chip->lock);
140 	for_each_set_bit(bit, mask, gc->ngpio)
141 		__gpio_mockup_set(chip, bit, test_bit(bit, bits));
142 	mutex_unlock(&chip->lock);
143 }
144 
145 static int gpio_mockup_apply_pull(struct gpio_mockup_chip *chip,
146 				  unsigned int offset, int value)
147 {
148 	struct gpio_chip *gc = &chip->gc;
149 	struct gpio_desc *desc = gpiochip_get_desc(gc, offset);
150 	int curr, irq, irq_type, ret = 0;
151 
152 	mutex_lock(&chip->lock);
153 
154 	if (test_bit(FLAG_REQUESTED, &desc->flags) &&
155 	    !test_bit(FLAG_IS_OUT, &desc->flags)) {
156 		curr = __gpio_mockup_get(chip, offset);
157 		if (curr == value)
158 			goto out;
159 
160 		irq = irq_find_mapping(chip->irq_sim_domain, offset);
161 		if (!irq)
162 			/*
163 			 * This is fine - it just means, nobody is listening
164 			 * for interrupts on this line, otherwise
165 			 * irq_create_mapping() would have been called from
166 			 * the to_irq() callback.
167 			 */
168 			goto set_value;
169 
170 		irq_type = irq_get_trigger_type(irq);
171 
172 		if ((value == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
173 		    (value == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING))) {
174 			ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING,
175 						    true);
176 			if (ret)
177 				goto out;
178 		}
179 	}
180 
181 set_value:
182 	/* Change the value unless we're actively driving the line. */
183 	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
184 	    !test_bit(FLAG_IS_OUT, &desc->flags))
185 		__gpio_mockup_set(chip, offset, value);
186 
187 out:
188 	chip->lines[offset].pull = value;
189 	mutex_unlock(&chip->lock);
190 	return ret;
191 }
192 
193 static int gpio_mockup_set_config(struct gpio_chip *gc,
194 				  unsigned int offset, unsigned long config)
195 {
196 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
197 
198 	switch (pinconf_to_config_param(config)) {
199 	case PIN_CONFIG_BIAS_PULL_UP:
200 		return gpio_mockup_apply_pull(chip, offset, 1);
201 	case PIN_CONFIG_BIAS_PULL_DOWN:
202 		return gpio_mockup_apply_pull(chip, offset, 0);
203 	default:
204 		break;
205 	}
206 	return -ENOTSUPP;
207 }
208 
209 static int gpio_mockup_dirout(struct gpio_chip *gc,
210 			      unsigned int offset, int value)
211 {
212 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
213 
214 	mutex_lock(&chip->lock);
215 	chip->lines[offset].dir = GPIO_LINE_DIRECTION_OUT;
216 	__gpio_mockup_set(chip, offset, value);
217 	mutex_unlock(&chip->lock);
218 
219 	return 0;
220 }
221 
222 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
223 {
224 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
225 
226 	mutex_lock(&chip->lock);
227 	chip->lines[offset].dir = GPIO_LINE_DIRECTION_IN;
228 	mutex_unlock(&chip->lock);
229 
230 	return 0;
231 }
232 
233 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
234 {
235 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
236 	int direction;
237 
238 	mutex_lock(&chip->lock);
239 	direction = chip->lines[offset].dir;
240 	mutex_unlock(&chip->lock);
241 
242 	return direction;
243 }
244 
245 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
246 {
247 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
248 
249 	return irq_create_mapping(chip->irq_sim_domain, offset);
250 }
251 
252 static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
253 {
254 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
255 
256 	__gpio_mockup_set(chip, offset, chip->lines[offset].pull);
257 }
258 
259 static ssize_t gpio_mockup_debugfs_read(struct file *file,
260 					char __user *usr_buf,
261 					size_t size, loff_t *ppos)
262 {
263 	struct gpio_mockup_dbgfs_private *priv;
264 	struct gpio_mockup_chip *chip;
265 	struct seq_file *sfile;
266 	struct gpio_chip *gc;
267 	int val, cnt;
268 	char buf[3];
269 
270 	if (*ppos != 0)
271 		return 0;
272 
273 	sfile = file->private_data;
274 	priv = sfile->private;
275 	chip = priv->chip;
276 	gc = &chip->gc;
277 
278 	val = gpio_mockup_get(gc, priv->offset);
279 	cnt = snprintf(buf, sizeof(buf), "%d\n", val);
280 
281 	return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt);
282 }
283 
284 static ssize_t gpio_mockup_debugfs_write(struct file *file,
285 					 const char __user *usr_buf,
286 					 size_t size, loff_t *ppos)
287 {
288 	struct gpio_mockup_dbgfs_private *priv;
289 	int rv, val;
290 	struct seq_file *sfile;
291 
292 	if (*ppos != 0)
293 		return -EINVAL;
294 
295 	rv = kstrtoint_from_user(usr_buf, size, 0, &val);
296 	if (rv)
297 		return rv;
298 	if (val != 0 && val != 1)
299 		return -EINVAL;
300 
301 	sfile = file->private_data;
302 	priv = sfile->private;
303 	rv = gpio_mockup_apply_pull(priv->chip, priv->offset, val);
304 	if (rv)
305 		return rv;
306 
307 	return size;
308 }
309 
310 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
311 {
312 	return single_open(file, NULL, inode->i_private);
313 }
314 
315 /*
316  * Each mockup chip is represented by a directory named after the chip's device
317  * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
318  * a file using the line's offset as the name under the chip's directory.
319  *
320  * Reading from the line's file yields the current *value*, writing to the
321  * line's file changes the current *pull*. Default pull for mockup lines is
322  * down.
323  *
324  * Examples:
325  * - when a line pulled down is requested in output mode and driven high, its
326  *   value will return to 0 once it's released
327  * - when the line is requested in output mode and driven high, writing 0 to
328  *   the corresponding debugfs file will change the pull to down but the
329  *   reported value will still be 1 until the line is released
330  * - line requested in input mode always reports the same value as its pull
331  *   configuration
332  * - when the line is requested in input mode and monitored for events, writing
333  *   the same value to the debugfs file will be a noop, while writing the
334  *   opposite value will generate a dummy interrupt with an appropriate edge
335  */
336 static const struct file_operations gpio_mockup_debugfs_ops = {
337 	.owner = THIS_MODULE,
338 	.open = gpio_mockup_debugfs_open,
339 	.read = gpio_mockup_debugfs_read,
340 	.write = gpio_mockup_debugfs_write,
341 	.llseek = no_llseek,
342 	.release = single_release,
343 };
344 
345 static void gpio_mockup_debugfs_setup(struct device *dev,
346 				      struct gpio_mockup_chip *chip)
347 {
348 	struct gpio_mockup_dbgfs_private *priv;
349 	struct gpio_chip *gc;
350 	const char *devname;
351 	char *name;
352 	int i;
353 
354 	gc = &chip->gc;
355 	devname = dev_name(&gc->gpiodev->dev);
356 
357 	chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
358 
359 	for (i = 0; i < gc->ngpio; i++) {
360 		name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
361 		if (!name)
362 			return;
363 
364 		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
365 		if (!priv)
366 			return;
367 
368 		priv->chip = chip;
369 		priv->offset = i;
370 		priv->desc = gpiochip_get_desc(gc, i);
371 
372 		debugfs_create_file(name, 0600, chip->dbg_dir, priv,
373 				    &gpio_mockup_debugfs_ops);
374 	}
375 }
376 
377 static void gpio_mockup_debugfs_cleanup(void *data)
378 {
379 	struct gpio_mockup_chip *chip = data;
380 
381 	debugfs_remove_recursive(chip->dbg_dir);
382 }
383 
384 static void gpio_mockup_dispose_mappings(void *data)
385 {
386 	struct gpio_mockup_chip *chip = data;
387 	struct gpio_chip *gc = &chip->gc;
388 	int i, irq;
389 
390 	for (i = 0; i < gc->ngpio; i++) {
391 		irq = irq_find_mapping(chip->irq_sim_domain, i);
392 		if (irq)
393 			irq_dispose_mapping(irq);
394 	}
395 }
396 
397 static int gpio_mockup_probe(struct platform_device *pdev)
398 {
399 	struct gpio_mockup_chip *chip;
400 	struct gpio_chip *gc;
401 	struct device *dev;
402 	const char *name;
403 	int rv, base, i;
404 	u16 ngpio;
405 
406 	dev = &pdev->dev;
407 
408 	rv = device_property_read_u32(dev, "gpio-base", &base);
409 	if (rv)
410 		base = -1;
411 
412 	rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
413 	if (rv)
414 		return rv;
415 
416 	rv = device_property_read_string(dev, "chip-label", &name);
417 	if (rv)
418 		name = dev_name(dev);
419 
420 	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
421 	if (!chip)
422 		return -ENOMEM;
423 
424 	mutex_init(&chip->lock);
425 
426 	gc = &chip->gc;
427 	gc->base = base;
428 	gc->ngpio = ngpio;
429 	gc->label = name;
430 	gc->owner = THIS_MODULE;
431 	gc->parent = dev;
432 	gc->get = gpio_mockup_get;
433 	gc->set = gpio_mockup_set;
434 	gc->get_multiple = gpio_mockup_get_multiple;
435 	gc->set_multiple = gpio_mockup_set_multiple;
436 	gc->direction_output = gpio_mockup_dirout;
437 	gc->direction_input = gpio_mockup_dirin;
438 	gc->get_direction = gpio_mockup_get_direction;
439 	gc->set_config = gpio_mockup_set_config;
440 	gc->to_irq = gpio_mockup_to_irq;
441 	gc->free = gpio_mockup_free;
442 
443 	chip->lines = devm_kcalloc(dev, gc->ngpio,
444 				   sizeof(*chip->lines), GFP_KERNEL);
445 	if (!chip->lines)
446 		return -ENOMEM;
447 
448 	for (i = 0; i < gc->ngpio; i++)
449 		chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
450 
451 	chip->irq_sim_domain = devm_irq_domain_create_sim(dev, NULL,
452 							  gc->ngpio);
453 	if (IS_ERR(chip->irq_sim_domain))
454 		return PTR_ERR(chip->irq_sim_domain);
455 
456 	rv = devm_add_action_or_reset(dev, gpio_mockup_dispose_mappings, chip);
457 	if (rv)
458 		return rv;
459 
460 	rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
461 	if (rv)
462 		return rv;
463 
464 	gpio_mockup_debugfs_setup(dev, chip);
465 
466 	return devm_add_action_or_reset(dev, gpio_mockup_debugfs_cleanup, chip);
467 }
468 
469 static const struct of_device_id gpio_mockup_of_match[] = {
470 	{ .compatible = "gpio-mockup", },
471 	{},
472 };
473 MODULE_DEVICE_TABLE(of, gpio_mockup_of_match);
474 
475 static struct platform_driver gpio_mockup_driver = {
476 	.driver = {
477 		.name = "gpio-mockup",
478 		.of_match_table = gpio_mockup_of_match,
479 	},
480 	.probe = gpio_mockup_probe,
481 };
482 
483 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
484 
485 static void gpio_mockup_unregister_pdevs(void)
486 {
487 	struct platform_device *pdev;
488 	struct fwnode_handle *fwnode;
489 	int i;
490 
491 	for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
492 		pdev = gpio_mockup_pdevs[i];
493 		if (!pdev)
494 			continue;
495 
496 		fwnode = dev_fwnode(&pdev->dev);
497 		platform_device_unregister(pdev);
498 		fwnode_remove_software_node(fwnode);
499 	}
500 }
501 
502 static int __init gpio_mockup_register_chip(int idx)
503 {
504 	struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
505 	struct platform_device_info pdevinfo;
506 	struct platform_device *pdev;
507 	struct fwnode_handle *fwnode;
508 	char **line_names = NULL;
509 	char chip_label[32];
510 	int prop = 0, base;
511 	u16 ngpio;
512 
513 	memset(properties, 0, sizeof(properties));
514 	memset(&pdevinfo, 0, sizeof(pdevinfo));
515 
516 	snprintf(chip_label, sizeof(chip_label), "gpio-mockup-%c", idx + 'A');
517 	properties[prop++] = PROPERTY_ENTRY_STRING("chip-label", chip_label);
518 
519 	base = gpio_mockup_range_base(idx);
520 	if (base >= 0)
521 		properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", base);
522 
523 	ngpio = base < 0 ? gpio_mockup_range_ngpio(idx)
524 			 : gpio_mockup_range_ngpio(idx) - base;
525 	properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
526 
527 	if (gpio_mockup_named_lines) {
528 		line_names = kasprintf_strarray(GFP_KERNEL, chip_label, ngpio);
529 		if (!line_names)
530 			return -ENOMEM;
531 
532 		properties[prop++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
533 					"gpio-line-names", line_names, ngpio);
534 	}
535 
536 	fwnode = fwnode_create_software_node(properties, NULL);
537 	if (IS_ERR(fwnode)) {
538 		kfree_strarray(line_names, ngpio);
539 		return PTR_ERR(fwnode);
540 	}
541 
542 	pdevinfo.name = "gpio-mockup";
543 	pdevinfo.id = idx;
544 	pdevinfo.fwnode = fwnode;
545 
546 	pdev = platform_device_register_full(&pdevinfo);
547 	kfree_strarray(line_names, ngpio);
548 	if (IS_ERR(pdev)) {
549 		fwnode_remove_software_node(fwnode);
550 		pr_err("error registering device");
551 		return PTR_ERR(pdev);
552 	}
553 
554 	gpio_mockup_pdevs[idx] = pdev;
555 
556 	return 0;
557 }
558 
559 static int __init gpio_mockup_init(void)
560 {
561 	int i, num_chips, err;
562 
563 	if ((gpio_mockup_num_ranges % 2) ||
564 	    (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
565 		return -EINVAL;
566 
567 	/* Each chip is described by two values. */
568 	num_chips = gpio_mockup_num_ranges / 2;
569 
570 	/*
571 	 * The second value in the <base GPIO - number of GPIOS> pair must
572 	 * always be greater than 0.
573 	 */
574 	for (i = 0; i < num_chips; i++) {
575 		if (gpio_mockup_range_ngpio(i) < 0)
576 			return -EINVAL;
577 	}
578 
579 	gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
580 
581 	err = platform_driver_register(&gpio_mockup_driver);
582 	if (err) {
583 		pr_err("error registering platform driver\n");
584 		debugfs_remove_recursive(gpio_mockup_dbg_dir);
585 		return err;
586 	}
587 
588 	for (i = 0; i < num_chips; i++) {
589 		err = gpio_mockup_register_chip(i);
590 		if (err) {
591 			platform_driver_unregister(&gpio_mockup_driver);
592 			gpio_mockup_unregister_pdevs();
593 			debugfs_remove_recursive(gpio_mockup_dbg_dir);
594 			return err;
595 		}
596 	}
597 
598 	return 0;
599 }
600 
601 static void __exit gpio_mockup_exit(void)
602 {
603 	gpio_mockup_unregister_pdevs();
604 	debugfs_remove_recursive(gpio_mockup_dbg_dir);
605 	platform_driver_unregister(&gpio_mockup_driver);
606 }
607 
608 module_init(gpio_mockup_init);
609 module_exit(gpio_mockup_exit);
610 
611 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
612 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
613 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
614 MODULE_DESCRIPTION("GPIO Testing driver");
615 MODULE_LICENSE("GPL v2");
616