xref: /linux/drivers/gpio/gpio-mockup.c (revision e9a83bd2322035ed9d7dcf35753d3f984d76c6a5) 
1 // SPDX-License-Identifier: GPL-2.0+
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 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/gpio/driver.h>
13 #include <linux/gpio/consumer.h>
14 #include <linux/platform_device.h>
15 #include <linux/slab.h>
16 #include <linux/interrupt.h>
17 #include <linux/irq.h>
18 #include <linux/irq_sim.h>
19 #include <linux/debugfs.h>
20 #include <linux/uaccess.h>
21 #include <linux/property.h>
22 
23 #include "gpiolib.h"
24 
25 #define GPIO_MOCKUP_NAME	"gpio-mockup"
26 #define GPIO_MOCKUP_MAX_GC	10
27 /*
28  * We're storing two values per chip: the GPIO base and the number
29  * of GPIO lines.
30  */
31 #define GPIO_MOCKUP_MAX_RANGES	(GPIO_MOCKUP_MAX_GC * 2)
32 /* Maximum of three properties + the sentinel. */
33 #define GPIO_MOCKUP_MAX_PROP	4
34 
35 #define gpio_mockup_err(...)	pr_err(GPIO_MOCKUP_NAME ": " __VA_ARGS__)
36 
37 enum {
38 	GPIO_MOCKUP_DIR_IN = 0,
39 	GPIO_MOCKUP_DIR_OUT = 1,
40 };
41 
42 /*
43  * struct gpio_pin_status - structure describing a GPIO status
44  * @dir:       Configures direction of gpio as "in" or "out", 0=in, 1=out
45  * @value:     Configures status of the gpio as 0(low) or 1(high)
46  */
47 struct gpio_mockup_line_status {
48 	int dir;
49 	int value;
50 	int pull;
51 };
52 
53 struct gpio_mockup_chip {
54 	struct gpio_chip gc;
55 	struct gpio_mockup_line_status *lines;
56 	struct irq_sim irqsim;
57 	struct dentry *dbg_dir;
58 	struct mutex lock;
59 };
60 
61 struct gpio_mockup_dbgfs_private {
62 	struct gpio_mockup_chip *chip;
63 	struct gpio_desc *desc;
64 	unsigned int offset;
65 };
66 
67 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
68 static int gpio_mockup_num_ranges;
69 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
70 
71 static bool gpio_mockup_named_lines;
72 module_param_named(gpio_mockup_named_lines,
73 		   gpio_mockup_named_lines, bool, 0400);
74 
75 static struct dentry *gpio_mockup_dbg_dir;
76 
77 static int gpio_mockup_range_base(unsigned int index)
78 {
79 	return gpio_mockup_ranges[index * 2];
80 }
81 
82 static int gpio_mockup_range_ngpio(unsigned int index)
83 {
84 	return gpio_mockup_ranges[index * 2 + 1];
85 }
86 
87 static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
88 			     unsigned int offset)
89 {
90 	return chip->lines[offset].value;
91 }
92 
93 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
94 {
95 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
96 	int val;
97 
98 	mutex_lock(&chip->lock);
99 	val = __gpio_mockup_get(chip, offset);
100 	mutex_unlock(&chip->lock);
101 
102 	return val;
103 }
104 
105 static int gpio_mockup_get_multiple(struct gpio_chip *gc,
106 				    unsigned long *mask, unsigned long *bits)
107 {
108 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
109 	unsigned int bit, val;
110 
111 	mutex_lock(&chip->lock);
112 	for_each_set_bit(bit, mask, gc->ngpio) {
113 		val = __gpio_mockup_get(chip, bit);
114 		__assign_bit(bit, bits, val);
115 	}
116 	mutex_unlock(&chip->lock);
117 
118 	return 0;
119 }
120 
121 static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
122 			      unsigned int offset, int value)
123 {
124 	chip->lines[offset].value = !!value;
125 }
126 
127 static void gpio_mockup_set(struct gpio_chip *gc,
128 			   unsigned int offset, int value)
129 {
130 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
131 
132 	mutex_lock(&chip->lock);
133 	__gpio_mockup_set(chip, offset, value);
134 	mutex_unlock(&chip->lock);
135 }
136 
137 static void gpio_mockup_set_multiple(struct gpio_chip *gc,
138 				     unsigned long *mask, unsigned long *bits)
139 {
140 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
141 	unsigned int bit;
142 
143 	mutex_lock(&chip->lock);
144 	for_each_set_bit(bit, mask, gc->ngpio)
145 		__gpio_mockup_set(chip, bit, test_bit(bit, bits));
146 	mutex_unlock(&chip->lock);
147 }
148 
149 static int gpio_mockup_dirout(struct gpio_chip *gc,
150 			      unsigned int offset, int value)
151 {
152 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
153 
154 	mutex_lock(&chip->lock);
155 	chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT;
156 	__gpio_mockup_set(chip, offset, value);
157 	mutex_unlock(&chip->lock);
158 
159 	return 0;
160 }
161 
162 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
163 {
164 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
165 
166 	mutex_lock(&chip->lock);
167 	chip->lines[offset].dir = GPIO_MOCKUP_DIR_IN;
168 	mutex_unlock(&chip->lock);
169 
170 	return 0;
171 }
172 
173 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
174 {
175 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
176 	int direction;
177 
178 	mutex_lock(&chip->lock);
179 	direction = !chip->lines[offset].dir;
180 	mutex_unlock(&chip->lock);
181 
182 	return direction;
183 }
184 
185 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
186 {
187 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
188 
189 	return irq_sim_irqnum(&chip->irqsim, offset);
190 }
191 
192 static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
193 {
194 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
195 
196 	__gpio_mockup_set(chip, offset, chip->lines[offset].pull);
197 }
198 
199 static ssize_t gpio_mockup_debugfs_read(struct file *file,
200 					char __user *usr_buf,
201 					size_t size, loff_t *ppos)
202 {
203 	struct gpio_mockup_dbgfs_private *priv;
204 	struct gpio_mockup_chip *chip;
205 	struct seq_file *sfile;
206 	struct gpio_chip *gc;
207 	int val, cnt;
208 	char buf[3];
209 
210 	if (*ppos != 0)
211 		return 0;
212 
213 	sfile = file->private_data;
214 	priv = sfile->private;
215 	chip = priv->chip;
216 	gc = &chip->gc;
217 
218 	val = gpio_mockup_get(gc, priv->offset);
219 	cnt = snprintf(buf, sizeof(buf), "%d\n", val);
220 
221 	return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt);
222 }
223 
224 static ssize_t gpio_mockup_debugfs_write(struct file *file,
225 					 const char __user *usr_buf,
226 					 size_t size, loff_t *ppos)
227 {
228 	struct gpio_mockup_dbgfs_private *priv;
229 	int rv, val, curr, irq, irq_type;
230 	struct gpio_mockup_chip *chip;
231 	struct seq_file *sfile;
232 	struct gpio_desc *desc;
233 	struct gpio_chip *gc;
234 	struct irq_sim *sim;
235 
236 	if (*ppos != 0)
237 		return -EINVAL;
238 
239 	rv = kstrtoint_from_user(usr_buf, size, 0, &val);
240 	if (rv)
241 		return rv;
242 	if (val != 0 && val != 1)
243 		return -EINVAL;
244 
245 	sfile = file->private_data;
246 	priv = sfile->private;
247 	chip = priv->chip;
248 	gc = &chip->gc;
249 	desc = &gc->gpiodev->descs[priv->offset];
250 	sim = &chip->irqsim;
251 
252 	mutex_lock(&chip->lock);
253 
254 	if (test_bit(FLAG_REQUESTED, &desc->flags) &&
255 	    !test_bit(FLAG_IS_OUT, &desc->flags)) {
256 		curr = __gpio_mockup_get(chip, priv->offset);
257 		if (curr == val)
258 			goto out;
259 
260 		irq = irq_sim_irqnum(sim, priv->offset);
261 		irq_type = irq_get_trigger_type(irq);
262 
263 		if ((val == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
264 		    (val == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING)))
265 			irq_sim_fire(sim, priv->offset);
266 	}
267 
268 	/* Change the value unless we're actively driving the line. */
269 	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
270 	    !test_bit(FLAG_IS_OUT, &desc->flags))
271 		__gpio_mockup_set(chip, priv->offset, val);
272 
273 out:
274 	chip->lines[priv->offset].pull = val;
275 	mutex_unlock(&chip->lock);
276 
277 	return size;
278 }
279 
280 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
281 {
282 	return single_open(file, NULL, inode->i_private);
283 }
284 
285 /*
286  * Each mockup chip is represented by a directory named after the chip's device
287  * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
288  * a file using the line's offset as the name under the chip's directory.
289  *
290  * Reading from the line's file yields the current *value*, writing to the
291  * line's file changes the current *pull*. Default pull for mockup lines is
292  * down.
293  *
294  * Examples:
295  * - when a line pulled down is requested in output mode and driven high, its
296  *   value will return to 0 once it's released
297  * - when the line is requested in output mode and driven high, writing 0 to
298  *   the corresponding debugfs file will change the pull to down but the
299  *   reported value will still be 1 until the line is released
300  * - line requested in input mode always reports the same value as its pull
301  *   configuration
302  * - when the line is requested in input mode and monitored for events, writing
303  *   the same value to the debugfs file will be a noop, while writing the
304  *   opposite value will generate a dummy interrupt with an appropriate edge
305  */
306 static const struct file_operations gpio_mockup_debugfs_ops = {
307 	.owner = THIS_MODULE,
308 	.open = gpio_mockup_debugfs_open,
309 	.read = gpio_mockup_debugfs_read,
310 	.write = gpio_mockup_debugfs_write,
311 	.llseek = no_llseek,
312 };
313 
314 static void gpio_mockup_debugfs_setup(struct device *dev,
315 				      struct gpio_mockup_chip *chip)
316 {
317 	struct gpio_mockup_dbgfs_private *priv;
318 	struct gpio_chip *gc;
319 	const char *devname;
320 	char *name;
321 	int i;
322 
323 	gc = &chip->gc;
324 	devname = dev_name(&gc->gpiodev->dev);
325 
326 	chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
327 
328 	for (i = 0; i < gc->ngpio; i++) {
329 		name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
330 		if (!name)
331 			return;
332 
333 		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
334 		if (!priv)
335 			return;
336 
337 		priv->chip = chip;
338 		priv->offset = i;
339 		priv->desc = &gc->gpiodev->descs[i];
340 
341 		debugfs_create_file(name, 0200, chip->dbg_dir, priv,
342 				    &gpio_mockup_debugfs_ops);
343 	}
344 
345 	return;
346 }
347 
348 static int gpio_mockup_name_lines(struct device *dev,
349 				  struct gpio_mockup_chip *chip)
350 {
351 	struct gpio_chip *gc = &chip->gc;
352 	char **names;
353 	int i;
354 
355 	names = devm_kcalloc(dev, gc->ngpio, sizeof(char *), GFP_KERNEL);
356 	if (!names)
357 		return -ENOMEM;
358 
359 	for (i = 0; i < gc->ngpio; i++) {
360 		names[i] = devm_kasprintf(dev, GFP_KERNEL,
361 					  "%s-%d", gc->label, i);
362 		if (!names[i])
363 			return -ENOMEM;
364 	}
365 
366 	gc->names = (const char *const *)names;
367 
368 	return 0;
369 }
370 
371 static int gpio_mockup_probe(struct platform_device *pdev)
372 {
373 	struct gpio_mockup_chip *chip;
374 	struct gpio_chip *gc;
375 	struct device *dev;
376 	const char *name;
377 	int rv, base;
378 	u16 ngpio;
379 
380 	dev = &pdev->dev;
381 
382 	rv = device_property_read_u32(dev, "gpio-base", &base);
383 	if (rv)
384 		base = -1;
385 
386 	rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
387 	if (rv)
388 		return rv;
389 
390 	rv = device_property_read_string(dev, "chip-name", &name);
391 	if (rv)
392 		name = NULL;
393 
394 	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
395 	if (!chip)
396 		return -ENOMEM;
397 
398 	if (!name) {
399 		name = devm_kasprintf(dev, GFP_KERNEL,
400 				      "%s-%c", pdev->name, pdev->id + 'A');
401 		if (!name)
402 			return -ENOMEM;
403 	}
404 
405 	mutex_init(&chip->lock);
406 
407 	gc = &chip->gc;
408 	gc->base = base;
409 	gc->ngpio = ngpio;
410 	gc->label = name;
411 	gc->owner = THIS_MODULE;
412 	gc->parent = dev;
413 	gc->get = gpio_mockup_get;
414 	gc->set = gpio_mockup_set;
415 	gc->get_multiple = gpio_mockup_get_multiple;
416 	gc->set_multiple = gpio_mockup_set_multiple;
417 	gc->direction_output = gpio_mockup_dirout;
418 	gc->direction_input = gpio_mockup_dirin;
419 	gc->get_direction = gpio_mockup_get_direction;
420 	gc->to_irq = gpio_mockup_to_irq;
421 	gc->free = gpio_mockup_free;
422 
423 	chip->lines = devm_kcalloc(dev, gc->ngpio,
424 				   sizeof(*chip->lines), GFP_KERNEL);
425 	if (!chip->lines)
426 		return -ENOMEM;
427 
428 	if (device_property_read_bool(dev, "named-gpio-lines")) {
429 		rv = gpio_mockup_name_lines(dev, chip);
430 		if (rv)
431 			return rv;
432 	}
433 
434 	rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio);
435 	if (rv < 0)
436 		return rv;
437 
438 	rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
439 	if (rv)
440 		return rv;
441 
442 	gpio_mockup_debugfs_setup(dev, chip);
443 
444 	return 0;
445 }
446 
447 static struct platform_driver gpio_mockup_driver = {
448 	.driver = {
449 		.name = GPIO_MOCKUP_NAME,
450 	},
451 	.probe = gpio_mockup_probe,
452 };
453 
454 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
455 
456 static void gpio_mockup_unregister_pdevs(void)
457 {
458 	struct platform_device *pdev;
459 	int i;
460 
461 	for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
462 		pdev = gpio_mockup_pdevs[i];
463 
464 		if (pdev)
465 			platform_device_unregister(pdev);
466 	}
467 }
468 
469 static int __init gpio_mockup_init(void)
470 {
471 	struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
472 	int i, prop, num_chips, err = 0, base;
473 	struct platform_device_info pdevinfo;
474 	struct platform_device *pdev;
475 	u16 ngpio;
476 
477 	if ((gpio_mockup_num_ranges < 2) ||
478 	    (gpio_mockup_num_ranges % 2) ||
479 	    (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
480 		return -EINVAL;
481 
482 	/* Each chip is described by two values. */
483 	num_chips = gpio_mockup_num_ranges / 2;
484 
485 	/*
486 	 * The second value in the <base GPIO - number of GPIOS> pair must
487 	 * always be greater than 0.
488 	 */
489 	for (i = 0; i < num_chips; i++) {
490 		if (gpio_mockup_range_ngpio(i) < 0)
491 			return -EINVAL;
492 	}
493 
494 	gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
495 
496 	err = platform_driver_register(&gpio_mockup_driver);
497 	if (err) {
498 		gpio_mockup_err("error registering platform driver\n");
499 		return err;
500 	}
501 
502 	for (i = 0; i < num_chips; i++) {
503 		memset(properties, 0, sizeof(properties));
504 		memset(&pdevinfo, 0, sizeof(pdevinfo));
505 		prop = 0;
506 
507 		base = gpio_mockup_range_base(i);
508 		if (base >= 0)
509 			properties[prop++] = PROPERTY_ENTRY_U32("gpio-base",
510 								base);
511 
512 		ngpio = base < 0 ? gpio_mockup_range_ngpio(i)
513 				 : gpio_mockup_range_ngpio(i) - base;
514 		properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
515 
516 		if (gpio_mockup_named_lines)
517 			properties[prop++] = PROPERTY_ENTRY_BOOL(
518 						"named-gpio-lines");
519 
520 		pdevinfo.name = GPIO_MOCKUP_NAME;
521 		pdevinfo.id = i;
522 		pdevinfo.properties = properties;
523 
524 		pdev = platform_device_register_full(&pdevinfo);
525 		if (IS_ERR(pdev)) {
526 			gpio_mockup_err("error registering device");
527 			platform_driver_unregister(&gpio_mockup_driver);
528 			gpio_mockup_unregister_pdevs();
529 			return PTR_ERR(pdev);
530 		}
531 
532 		gpio_mockup_pdevs[i] = pdev;
533 	}
534 
535 	return 0;
536 }
537 
538 static void __exit gpio_mockup_exit(void)
539 {
540 	debugfs_remove_recursive(gpio_mockup_dbg_dir);
541 	platform_driver_unregister(&gpio_mockup_driver);
542 	gpio_mockup_unregister_pdevs();
543 }
544 
545 module_init(gpio_mockup_init);
546 module_exit(gpio_mockup_exit);
547 
548 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
549 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
550 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
551 MODULE_DESCRIPTION("GPIO Testing driver");
552 MODULE_LICENSE("GPL v2");
553