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/cleanup.h>
13 #include <linux/debugfs.h>
14 #include <linux/device.h>
15 #include <linux/gpio/driver.h>
16 #include <linux/interrupt.h>
17 #include <linux/irq.h>
18 #include <linux/irq_sim.h>
19 #include <linux/irqdomain.h>
20 #include <linux/mod_devicetable.h>
21 #include <linux/module.h>
22 #include <linux/platform_device.h>
23 #include <linux/property.h>
24 #include <linux/seq_file.h>
25 #include <linux/slab.h>
26 #include <linux/string_helpers.h>
27 #include <linux/uaccess.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 * @pull: Configures the current pull of the GPIO as 0 (pull-down) or
43 * 1 (pull-up)
44 * @requested: Request status of this GPIO
45 */
46 struct gpio_mockup_line_status {
47 int dir;
48 int value;
49 int pull;
50 bool requested;
51 };
52
53 struct gpio_mockup_chip {
54 struct gpio_chip gc;
55 struct gpio_mockup_line_status *lines;
56 struct irq_domain *irq_sim_domain;
57 struct dentry *dbg_dir;
58 struct mutex lock;
59 };
60
61 struct gpio_mockup_dbgfs_private {
62 struct gpio_mockup_chip *chip;
63 unsigned int offset;
64 };
65
66 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
67 static int gpio_mockup_num_ranges;
68 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
69
70 static bool gpio_mockup_named_lines;
71 module_param_named(gpio_mockup_named_lines,
72 gpio_mockup_named_lines, bool, 0400);
73
74 static struct dentry *gpio_mockup_dbg_dir;
75
gpio_mockup_range_base(unsigned int index)76 static int gpio_mockup_range_base(unsigned int index)
77 {
78 return gpio_mockup_ranges[index * 2];
79 }
80
gpio_mockup_range_ngpio(unsigned int index)81 static int gpio_mockup_range_ngpio(unsigned int index)
82 {
83 return gpio_mockup_ranges[index * 2 + 1];
84 }
85
__gpio_mockup_get(struct gpio_mockup_chip * chip,unsigned int offset)86 static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
87 unsigned int offset)
88 {
89 return chip->lines[offset].value;
90 }
91
gpio_mockup_get(struct gpio_chip * gc,unsigned int offset)92 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
93 {
94 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
95 int val;
96
97 scoped_guard(mutex, &chip->lock)
98 val = __gpio_mockup_get(chip, offset);
99
100 return val;
101 }
102
gpio_mockup_get_multiple(struct gpio_chip * gc,unsigned long * mask,unsigned long * bits)103 static int gpio_mockup_get_multiple(struct gpio_chip *gc,
104 unsigned long *mask, unsigned long *bits)
105 {
106 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
107 unsigned int bit, val;
108
109 scoped_guard(mutex, &chip->lock) {
110 for_each_set_bit(bit, mask, gc->ngpio) {
111 val = __gpio_mockup_get(chip, bit);
112 __assign_bit(bit, bits, val);
113 }
114 }
115
116 return 0;
117 }
118
__gpio_mockup_set(struct gpio_mockup_chip * chip,unsigned int offset,int value)119 static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
120 unsigned int offset, int value)
121 {
122 chip->lines[offset].value = !!value;
123 }
124
gpio_mockup_set(struct gpio_chip * gc,unsigned int offset,int value)125 static int gpio_mockup_set(struct gpio_chip *gc,
126 unsigned int offset, int value)
127 {
128 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
129
130 guard(mutex)(&chip->lock);
131
132 __gpio_mockup_set(chip, offset, value);
133
134 return 0;
135 }
136
gpio_mockup_set_multiple(struct gpio_chip * gc,unsigned long * mask,unsigned long * bits)137 static int 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 guard(mutex)(&chip->lock);
144
145 for_each_set_bit(bit, mask, gc->ngpio)
146 __gpio_mockup_set(chip, bit, test_bit(bit, bits));
147
148 return 0;
149 }
150
gpio_mockup_apply_pull(struct gpio_mockup_chip * chip,unsigned int offset,int value)151 static int gpio_mockup_apply_pull(struct gpio_mockup_chip *chip,
152 unsigned int offset, int value)
153 {
154 struct gpio_mockup_line_status *line = &chip->lines[offset];
155 int curr, irq, irq_type, ret = 0;
156
157 guard(mutex)(&chip->lock);
158
159 if (line->requested && line->dir == GPIO_LINE_DIRECTION_IN) {
160 curr = __gpio_mockup_get(chip, offset);
161 if (curr == value)
162 goto out;
163
164 irq = irq_find_mapping(chip->irq_sim_domain, offset);
165 if (!irq)
166 /*
167 * This is fine - it just means, nobody is listening
168 * for interrupts on this line, otherwise
169 * irq_create_mapping() would have been called from
170 * the to_irq() callback.
171 */
172 goto set_value;
173
174 irq_type = irq_get_trigger_type(irq);
175
176 if ((value == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
177 (value == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING))) {
178 ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING,
179 true);
180 if (ret)
181 goto out;
182 }
183 }
184
185 set_value:
186 /* Change the value unless we're actively driving the line. */
187 if (!line->requested || line->dir == GPIO_LINE_DIRECTION_IN)
188 __gpio_mockup_set(chip, offset, value);
189
190 out:
191 chip->lines[offset].pull = value;
192 return ret;
193 }
194
gpio_mockup_set_config(struct gpio_chip * gc,unsigned int offset,unsigned long config)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
gpio_mockup_dirout(struct gpio_chip * gc,unsigned int offset,int value)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 scoped_guard(mutex, &chip->lock) {
217 chip->lines[offset].dir = GPIO_LINE_DIRECTION_OUT;
218 __gpio_mockup_set(chip, offset, value);
219 }
220
221 return 0;
222 }
223
gpio_mockup_dirin(struct gpio_chip * gc,unsigned int offset)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 scoped_guard(mutex, &chip->lock)
229 chip->lines[offset].dir = GPIO_LINE_DIRECTION_IN;
230
231 return 0;
232 }
233
gpio_mockup_get_direction(struct gpio_chip * gc,unsigned int offset)234 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
235 {
236 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
237 int direction;
238
239 scoped_guard(mutex, &chip->lock)
240 direction = chip->lines[offset].dir;
241
242 return direction;
243 }
244
gpio_mockup_to_irq(struct gpio_chip * gc,unsigned int offset)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
gpio_mockup_request(struct gpio_chip * gc,unsigned int offset)252 static int gpio_mockup_request(struct gpio_chip *gc, unsigned int offset)
253 {
254 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
255
256 scoped_guard(mutex, &chip->lock)
257 chip->lines[offset].requested = true;
258
259 return 0;
260 }
261
gpio_mockup_free(struct gpio_chip * gc,unsigned int offset)262 static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
263 {
264 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
265
266 guard(mutex)(&chip->lock);
267
268 chip->lines[offset].requested = false;
269 __gpio_mockup_set(chip, offset, chip->lines[offset].pull);
270 }
271
gpio_mockup_debugfs_read(struct file * file,char __user * usr_buf,size_t size,loff_t * ppos)272 static ssize_t gpio_mockup_debugfs_read(struct file *file,
273 char __user *usr_buf,
274 size_t size, loff_t *ppos)
275 {
276 struct gpio_mockup_dbgfs_private *priv;
277 struct gpio_mockup_chip *chip;
278 struct seq_file *sfile;
279 struct gpio_chip *gc;
280 int val, cnt;
281 char buf[3];
282
283 if (*ppos != 0)
284 return 0;
285
286 sfile = file->private_data;
287 priv = sfile->private;
288 chip = priv->chip;
289 gc = &chip->gc;
290
291 val = gpio_mockup_get(gc, priv->offset);
292 cnt = snprintf(buf, sizeof(buf), "%d\n", val);
293
294 return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt);
295 }
296
gpio_mockup_debugfs_write(struct file * file,const char __user * usr_buf,size_t size,loff_t * ppos)297 static ssize_t gpio_mockup_debugfs_write(struct file *file,
298 const char __user *usr_buf,
299 size_t size, loff_t *ppos)
300 {
301 struct gpio_mockup_dbgfs_private *priv;
302 int rv, val;
303 struct seq_file *sfile;
304
305 if (*ppos != 0)
306 return -EINVAL;
307
308 rv = kstrtoint_from_user(usr_buf, size, 0, &val);
309 if (rv)
310 return rv;
311 if (val != 0 && val != 1)
312 return -EINVAL;
313
314 sfile = file->private_data;
315 priv = sfile->private;
316 rv = gpio_mockup_apply_pull(priv->chip, priv->offset, val);
317 if (rv)
318 return rv;
319
320 return size;
321 }
322
gpio_mockup_debugfs_open(struct inode * inode,struct file * file)323 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
324 {
325 return single_open(file, NULL, inode->i_private);
326 }
327
328 /*
329 * Each mockup chip is represented by a directory named after the chip's device
330 * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
331 * a file using the line's offset as the name under the chip's directory.
332 *
333 * Reading from the line's file yields the current *value*, writing to the
334 * line's file changes the current *pull*. Default pull for mockup lines is
335 * down.
336 *
337 * Examples:
338 * - when a line pulled down is requested in output mode and driven high, its
339 * value will return to 0 once it's released
340 * - when the line is requested in output mode and driven high, writing 0 to
341 * the corresponding debugfs file will change the pull to down but the
342 * reported value will still be 1 until the line is released
343 * - line requested in input mode always reports the same value as its pull
344 * configuration
345 * - when the line is requested in input mode and monitored for events, writing
346 * the same value to the debugfs file will be a noop, while writing the
347 * opposite value will generate a dummy interrupt with an appropriate edge
348 */
349 static const struct file_operations gpio_mockup_debugfs_ops = {
350 .owner = THIS_MODULE,
351 .open = gpio_mockup_debugfs_open,
352 .read = gpio_mockup_debugfs_read,
353 .write = gpio_mockup_debugfs_write,
354 .release = single_release,
355 };
356
gpio_mockup_debugfs_setup(struct device * dev,struct gpio_mockup_chip * chip)357 static void gpio_mockup_debugfs_setup(struct device *dev,
358 struct gpio_mockup_chip *chip)
359 {
360 struct gpio_mockup_dbgfs_private *priv;
361 struct gpio_chip *gc;
362 const char *devname;
363 char *name;
364 int i;
365
366 gc = &chip->gc;
367
368 /*
369 * There can only be a single GPIO device per platform device in
370 * gpio-mockup so using device_find_any_child() is OK.
371 */
372 struct device *child __free(put_device) = device_find_any_child(dev);
373 if (!child)
374 return;
375
376 devname = dev_name(child);
377 chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
378
379 for (i = 0; i < gc->ngpio; i++) {
380 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
381 if (!name)
382 return;
383
384 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
385 if (!priv)
386 return;
387
388 priv->chip = chip;
389 priv->offset = i;
390
391 debugfs_create_file(name, 0600, chip->dbg_dir, priv,
392 &gpio_mockup_debugfs_ops);
393 }
394 }
395
gpio_mockup_debugfs_cleanup(void * data)396 static void gpio_mockup_debugfs_cleanup(void *data)
397 {
398 struct gpio_mockup_chip *chip = data;
399
400 debugfs_remove_recursive(chip->dbg_dir);
401 }
402
gpio_mockup_dispose_mappings(void * data)403 static void gpio_mockup_dispose_mappings(void *data)
404 {
405 struct gpio_mockup_chip *chip = data;
406 struct gpio_chip *gc = &chip->gc;
407 int i, irq;
408
409 for (i = 0; i < gc->ngpio; i++) {
410 irq = irq_find_mapping(chip->irq_sim_domain, i);
411 if (irq)
412 irq_dispose_mapping(irq);
413 }
414 }
415
gpio_mockup_probe(struct platform_device * pdev)416 static int gpio_mockup_probe(struct platform_device *pdev)
417 {
418 struct gpio_mockup_chip *chip;
419 struct gpio_chip *gc;
420 struct device *dev;
421 const char *name;
422 int rv, base, i;
423 u16 ngpio;
424
425 dev = &pdev->dev;
426
427 rv = device_property_read_u32(dev, "gpio-base", &base);
428 if (rv)
429 base = -1;
430
431 rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
432 if (rv)
433 return rv;
434
435 rv = device_property_read_string(dev, "chip-label", &name);
436 if (rv)
437 name = dev_name(dev);
438
439 chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
440 if (!chip)
441 return -ENOMEM;
442
443 mutex_init(&chip->lock);
444
445 gc = &chip->gc;
446 gc->base = base;
447 gc->ngpio = ngpio;
448 gc->label = name;
449 gc->owner = THIS_MODULE;
450 gc->parent = dev;
451 gc->get = gpio_mockup_get;
452 gc->set_rv = gpio_mockup_set;
453 gc->get_multiple = gpio_mockup_get_multiple;
454 gc->set_multiple_rv = gpio_mockup_set_multiple;
455 gc->direction_output = gpio_mockup_dirout;
456 gc->direction_input = gpio_mockup_dirin;
457 gc->get_direction = gpio_mockup_get_direction;
458 gc->set_config = gpio_mockup_set_config;
459 gc->to_irq = gpio_mockup_to_irq;
460 gc->request = gpio_mockup_request;
461 gc->free = gpio_mockup_free;
462
463 chip->lines = devm_kcalloc(dev, gc->ngpio,
464 sizeof(*chip->lines), GFP_KERNEL);
465 if (!chip->lines)
466 return -ENOMEM;
467
468 for (i = 0; i < gc->ngpio; i++)
469 chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
470
471 chip->irq_sim_domain = devm_irq_domain_create_sim(dev, NULL,
472 gc->ngpio);
473 if (IS_ERR(chip->irq_sim_domain))
474 return PTR_ERR(chip->irq_sim_domain);
475
476 rv = devm_add_action_or_reset(dev, gpio_mockup_dispose_mappings, chip);
477 if (rv)
478 return rv;
479
480 rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
481 if (rv)
482 return rv;
483
484 gpio_mockup_debugfs_setup(dev, chip);
485
486 return devm_add_action_or_reset(dev, gpio_mockup_debugfs_cleanup, chip);
487 }
488
489 static const struct of_device_id gpio_mockup_of_match[] = {
490 { .compatible = "gpio-mockup", },
491 {},
492 };
493 MODULE_DEVICE_TABLE(of, gpio_mockup_of_match);
494
495 static struct platform_driver gpio_mockup_driver = {
496 .driver = {
497 .name = "gpio-mockup",
498 .of_match_table = gpio_mockup_of_match,
499 },
500 .probe = gpio_mockup_probe,
501 };
502
503 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
504
gpio_mockup_unregister_pdevs(void)505 static void gpio_mockup_unregister_pdevs(void)
506 {
507 struct platform_device *pdev;
508 struct fwnode_handle *fwnode;
509 int i;
510
511 for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
512 pdev = gpio_mockup_pdevs[i];
513 if (!pdev)
514 continue;
515
516 fwnode = dev_fwnode(&pdev->dev);
517 platform_device_unregister(pdev);
518 fwnode_remove_software_node(fwnode);
519 }
520 }
521
gpio_mockup_register_chip(int idx)522 static int __init gpio_mockup_register_chip(int idx)
523 {
524 struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
525 struct platform_device_info pdevinfo;
526 struct platform_device *pdev;
527 struct fwnode_handle *fwnode;
528 char **line_names = NULL;
529 char chip_label[32];
530 int prop = 0, base;
531 u16 ngpio;
532
533 memset(properties, 0, sizeof(properties));
534 memset(&pdevinfo, 0, sizeof(pdevinfo));
535
536 snprintf(chip_label, sizeof(chip_label), "gpio-mockup-%c", idx + 'A');
537 properties[prop++] = PROPERTY_ENTRY_STRING("chip-label", chip_label);
538
539 base = gpio_mockup_range_base(idx);
540 if (base >= 0)
541 properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", base);
542
543 ngpio = base < 0 ? gpio_mockup_range_ngpio(idx)
544 : gpio_mockup_range_ngpio(idx) - base;
545 properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
546
547 if (gpio_mockup_named_lines) {
548 line_names = kasprintf_strarray(GFP_KERNEL, chip_label, ngpio);
549 if (!line_names)
550 return -ENOMEM;
551
552 properties[prop++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
553 "gpio-line-names", line_names, ngpio);
554 }
555
556 fwnode = fwnode_create_software_node(properties, NULL);
557 if (IS_ERR(fwnode)) {
558 kfree_strarray(line_names, ngpio);
559 return PTR_ERR(fwnode);
560 }
561
562 pdevinfo.name = "gpio-mockup";
563 pdevinfo.id = idx;
564 pdevinfo.fwnode = fwnode;
565
566 pdev = platform_device_register_full(&pdevinfo);
567 kfree_strarray(line_names, ngpio);
568 if (IS_ERR(pdev)) {
569 fwnode_remove_software_node(fwnode);
570 pr_err("error registering device");
571 return PTR_ERR(pdev);
572 }
573
574 gpio_mockup_pdevs[idx] = pdev;
575
576 return 0;
577 }
578
gpio_mockup_init(void)579 static int __init gpio_mockup_init(void)
580 {
581 int i, num_chips, err;
582
583 if ((gpio_mockup_num_ranges % 2) ||
584 (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
585 return -EINVAL;
586
587 /* Each chip is described by two values. */
588 num_chips = gpio_mockup_num_ranges / 2;
589
590 /*
591 * The second value in the <base GPIO - number of GPIOS> pair must
592 * always be greater than 0.
593 */
594 for (i = 0; i < num_chips; i++) {
595 if (gpio_mockup_range_ngpio(i) < 0)
596 return -EINVAL;
597 }
598
599 gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
600
601 err = platform_driver_register(&gpio_mockup_driver);
602 if (err) {
603 pr_err("error registering platform driver\n");
604 debugfs_remove_recursive(gpio_mockup_dbg_dir);
605 return err;
606 }
607
608 for (i = 0; i < num_chips; i++) {
609 err = gpio_mockup_register_chip(i);
610 if (err) {
611 platform_driver_unregister(&gpio_mockup_driver);
612 gpio_mockup_unregister_pdevs();
613 debugfs_remove_recursive(gpio_mockup_dbg_dir);
614 return err;
615 }
616 }
617
618 return 0;
619 }
620
gpio_mockup_exit(void)621 static void __exit gpio_mockup_exit(void)
622 {
623 gpio_mockup_unregister_pdevs();
624 debugfs_remove_recursive(gpio_mockup_dbg_dir);
625 platform_driver_unregister(&gpio_mockup_driver);
626 }
627
628 module_init(gpio_mockup_init);
629 module_exit(gpio_mockup_exit);
630
631 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
632 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
633 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
634 MODULE_DESCRIPTION("GPIO Testing driver");
635 MODULE_LICENSE("GPL v2");
636