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