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
gpio_mockup_range_base(unsigned int index)73 static int gpio_mockup_range_base(unsigned int index)
74 {
75 return gpio_mockup_ranges[index * 2];
76 }
77
gpio_mockup_range_ngpio(unsigned int index)78 static int gpio_mockup_range_ngpio(unsigned int index)
79 {
80 return gpio_mockup_ranges[index * 2 + 1];
81 }
82
__gpio_mockup_get(struct gpio_mockup_chip * chip,unsigned int offset)83 static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
84 unsigned int offset)
85 {
86 return chip->lines[offset].value;
87 }
88
gpio_mockup_get(struct gpio_chip * gc,unsigned int offset)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
gpio_mockup_get_multiple(struct gpio_chip * gc,unsigned long * mask,unsigned long * bits)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
__gpio_mockup_set(struct gpio_mockup_chip * chip,unsigned int offset,int value)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
gpio_mockup_set(struct gpio_chip * gc,unsigned int offset,int value)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
gpio_mockup_set_multiple(struct gpio_chip * gc,unsigned long * mask,unsigned long * bits)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
gpio_mockup_apply_pull(struct gpio_mockup_chip * chip,unsigned int offset,int value)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
gpio_mockup_set_config(struct gpio_chip * gc,unsigned int offset,unsigned long config)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
gpio_mockup_dirout(struct gpio_chip * gc,unsigned int offset,int value)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
gpio_mockup_dirin(struct gpio_chip * gc,unsigned int offset)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
gpio_mockup_get_direction(struct gpio_chip * gc,unsigned int offset)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
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_free(struct gpio_chip * gc,unsigned int offset)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
gpio_mockup_debugfs_read(struct file * file,char __user * usr_buf,size_t size,loff_t * ppos)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
gpio_mockup_debugfs_write(struct file * file,const char __user * usr_buf,size_t size,loff_t * ppos)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
gpio_mockup_debugfs_open(struct inode * inode,struct file * file)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
gpio_mockup_debugfs_setup(struct device * dev,struct gpio_mockup_chip * chip)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
gpio_mockup_debugfs_cleanup(void * data)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
gpio_mockup_dispose_mappings(void * data)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
gpio_mockup_probe(struct platform_device * pdev)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
gpio_mockup_unregister_pdevs(void)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
gpio_mockup_register_chip(int idx)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
gpio_mockup_init(void)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
gpio_mockup_exit(void)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