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
37enum {
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 */
47struct gpio_mockup_line_status {
48 int dir;
49 int value;
50 int pull;
51};
52
53struct 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
61struct gpio_mockup_dbgfs_private {
62 struct gpio_mockup_chip *chip;
63 struct gpio_desc *desc;
64 unsigned int offset;
65};
66
67static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
68static int gpio_mockup_num_ranges;
69module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
70
71static bool gpio_mockup_named_lines;
72module_param_named(gpio_mockup_named_lines,
73 gpio_mockup_named_lines, bool, 0400);
74
75static struct dentry *gpio_mockup_dbg_dir;
76
77static int gpio_mockup_range_base(unsigned int index)
78{
79 return gpio_mockup_ranges[index * 2];
80}
81
82static int gpio_mockup_range_ngpio(unsigned int index)
83{
84 return gpio_mockup_ranges[index * 2 + 1];
85}
86
87static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
88 unsigned int offset)
89{
90 return chip->lines[offset].value;
91}
92
93static 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
105static 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
121static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
122 unsigned int offset, int value)
123{
124 chip->lines[offset].value = !!value;
125}
126
127static 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
137static 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
149static 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
162static 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
173static 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
185static 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
192static 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
199static 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 char buf[3];
208 int val, rv;
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 snprintf(buf, sizeof(buf), "%d\n", val);
220
221 rv = copy_to_user(usr_buf, buf, sizeof(buf));
222 if (rv)
223 return rv;
224
225 return sizeof(buf) - 1;
226}
227
228static ssize_t gpio_mockup_debugfs_write(struct file *file,
229 const char __user *usr_buf,
230 size_t size, loff_t *ppos)
231{
232 struct gpio_mockup_dbgfs_private *priv;
233 int rv, val, curr, irq, irq_type;
234 struct gpio_mockup_chip *chip;
235 struct seq_file *sfile;
236 struct gpio_desc *desc;
237 struct gpio_chip *gc;
238 struct irq_sim *sim;
239
240 if (*ppos != 0)
241 return -EINVAL;
242
243 rv = kstrtoint_from_user(usr_buf, size, 0, &val);
244 if (rv)
245 return rv;
246 if (val != 0 && val != 1)
247 return -EINVAL;
248
249 sfile = file->private_data;
250 priv = sfile->private;
251 chip = priv->chip;
252 gc = &chip->gc;
253 desc = &gc->gpiodev->descs[priv->offset];
254 sim = &chip->irqsim;
255
256 mutex_lock(&chip->lock);
257
258 if (test_bit(FLAG_REQUESTED, &desc->flags) &&
259 !test_bit(FLAG_IS_OUT, &desc->flags)) {
260 curr = __gpio_mockup_get(chip, priv->offset);
261 if (curr == val)
262 goto out;
263
264 irq = irq_sim_irqnum(sim, priv->offset);
265 irq_type = irq_get_trigger_type(irq);
266
267 if ((val == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
268 (val == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING)))
269 irq_sim_fire(sim, priv->offset);
270 }
271
272 /* Change the value unless we're actively driving the line. */
273 if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
274 !test_bit(FLAG_IS_OUT, &desc->flags))
275 __gpio_mockup_set(chip, priv->offset, val);
276
277out:
278 chip->lines[priv->offset].pull = val;
279 mutex_unlock(&chip->lock);
280
281 return size;
282}
283
284static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
285{
286 return single_open(file, NULL, inode->i_private);
287}
288
289/*
290 * Each mockup chip is represented by a directory named after the chip's device
291 * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
292 * a file using the line's offset as the name under the chip's directory.
293 *
294 * Reading from the line's file yields the current *value*, writing to the
295 * line's file changes the current *pull*. Default pull for mockup lines is
296 * down.
297 *
298 * Examples:
299 * - when a line pulled down is requested in output mode and driven high, its
300 * value will return to 0 once it's released
301 * - when the line is requested in output mode and driven high, writing 0 to
302 * the corresponding debugfs file will change the pull to down but the
303 * reported value will still be 1 until the line is released
304 * - line requested in input mode always reports the same value as its pull
305 * configuration
306 * - when the line is requested in input mode and monitored for events, writing
307 * the same value to the debugfs file will be a noop, while writing the
308 * opposite value will generate a dummy interrupt with an appropriate edge
309 */
310static const struct file_operations gpio_mockup_debugfs_ops = {
311 .owner = THIS_MODULE,
312 .open = gpio_mockup_debugfs_open,
313 .read = gpio_mockup_debugfs_read,
314 .write = gpio_mockup_debugfs_write,
315 .llseek = no_llseek,
316};
317
318static void gpio_mockup_debugfs_setup(struct device *dev,
319 struct gpio_mockup_chip *chip)
320{
321 struct gpio_mockup_dbgfs_private *priv;
322 struct dentry *evfile;
323 struct gpio_chip *gc;
324 const char *devname;
325 char *name;
326 int i;
327
328 gc = &chip->gc;
329 devname = dev_name(&gc->gpiodev->dev);
330
331 chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
332 if (IS_ERR_OR_NULL(chip->dbg_dir))
333 goto err;
334
335 for (i = 0; i < gc->ngpio; i++) {
336 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
337 if (!name)
338 goto err;
339
340 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
341 if (!priv)
342 goto err;
343
344 priv->chip = chip;
345 priv->offset = i;
346 priv->desc = &gc->gpiodev->descs[i];
347
348 evfile = debugfs_create_file(name, 0200, chip->dbg_dir, priv,
349 &gpio_mockup_debugfs_ops);
350 if (IS_ERR_OR_NULL(evfile))
351 goto err;
352 }
353
354 return;
355
356err:
357 dev_err(dev, "error creating debugfs files\n");
358}
359
360static int gpio_mockup_name_lines(struct device *dev,
361 struct gpio_mockup_chip *chip)
362{
363 struct gpio_chip *gc = &chip->gc;
364 char **names;
365 int i;
366
367 names = devm_kcalloc(dev, gc->ngpio, sizeof(char *), GFP_KERNEL);
368 if (!names)
369 return -ENOMEM;
370
371 for (i = 0; i < gc->ngpio; i++) {
372 names[i] = devm_kasprintf(dev, GFP_KERNEL,
373 "%s-%d", gc->label, i);
374 if (!names[i])
375 return -ENOMEM;
376 }
377
378 gc->names = (const char *const *)names;
379
380 return 0;
381}
382
383static int gpio_mockup_probe(struct platform_device *pdev)
384{
385 struct gpio_mockup_chip *chip;
386 struct gpio_chip *gc;
387 struct device *dev;
388 const char *name;
389 int rv, base;
390 u16 ngpio;
391
392 dev = &pdev->dev;
393
394 rv = device_property_read_u32(dev, "gpio-base", &base);
395 if (rv)
396 base = -1;
397
398 rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
399 if (rv)
400 return rv;
401
402 rv = device_property_read_string(dev, "chip-name", &name);
403 if (rv)
404 name = NULL;
405
406 chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
407 if (!chip)
408 return -ENOMEM;
409
410 if (!name) {
411 name = devm_kasprintf(dev, GFP_KERNEL,
412 "%s-%c", pdev->name, pdev->id + 'A');
413 if (!name)
414 return -ENOMEM;
415 }
416
417 mutex_init(&chip->lock);
418
419 gc = &chip->gc;
420 gc->base = base;
421 gc->ngpio = ngpio;
422 gc->label = name;
423 gc->owner = THIS_MODULE;
424 gc->parent = dev;
425 gc->get = gpio_mockup_get;
426 gc->set = gpio_mockup_set;
427 gc->get_multiple = gpio_mockup_get_multiple;
428 gc->set_multiple = gpio_mockup_set_multiple;
429 gc->direction_output = gpio_mockup_dirout;
430 gc->direction_input = gpio_mockup_dirin;
431 gc->get_direction = gpio_mockup_get_direction;
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 if (device_property_read_bool(dev, "named-gpio-lines")) {
441 rv = gpio_mockup_name_lines(dev, chip);
442 if (rv)
443 return rv;
444 }
445
446 rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio);
447 if (rv < 0)
448 return rv;
449
450 rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
451 if (rv)
452 return rv;
453
454 if (!IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
455 gpio_mockup_debugfs_setup(dev, chip);
456
457 return 0;
458}
459
460static struct platform_driver gpio_mockup_driver = {
461 .driver = {
462 .name = GPIO_MOCKUP_NAME,
463 },
464 .probe = gpio_mockup_probe,
465};
466
467static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
468
469static void gpio_mockup_unregister_pdevs(void)
470{
471 struct platform_device *pdev;
472 int i;
473
474 for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
475 pdev = gpio_mockup_pdevs[i];
476
477 if (pdev)
478 platform_device_unregister(pdev);
479 }
480}
481
482static int __init gpio_mockup_init(void)
483{
484 struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
485 int i, prop, num_chips, err = 0, base;
486 struct platform_device_info pdevinfo;
487 struct platform_device *pdev;
488 u16 ngpio;
489
490 if ((gpio_mockup_num_ranges < 2) ||
491 (gpio_mockup_num_ranges % 2) ||
492 (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
493 return -EINVAL;
494
495 /* Each chip is described by two values. */
496 num_chips = gpio_mockup_num_ranges / 2;
497
498 /*
499 * The second value in the <base GPIO - number of GPIOS> pair must
500 * always be greater than 0.
501 */
502 for (i = 0; i < num_chips; i++) {
503 if (gpio_mockup_range_ngpio(i) < 0)
504 return -EINVAL;
505 }
506
507 gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
508 if (IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
509 gpio_mockup_err("error creating debugfs directory\n");
510
511 err = platform_driver_register(&gpio_mockup_driver);
512 if (err) {
513 gpio_mockup_err("error registering platform driver\n");
514 return err;
515 }
516
517 for (i = 0; i < num_chips; i++) {
518 memset(properties, 0, sizeof(properties));
519 memset(&pdevinfo, 0, sizeof(pdevinfo));
520 prop = 0;
521
522 base = gpio_mockup_range_base(i);
523 if (base >= 0)
524 properties[prop++] = PROPERTY_ENTRY_U32("gpio-base",
525 base);
526
527 ngpio = base < 0 ? gpio_mockup_range_ngpio(i)
528 : gpio_mockup_range_ngpio(i) - base;
529 properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
530
531 if (gpio_mockup_named_lines)
532 properties[prop++] = PROPERTY_ENTRY_BOOL(
533 "named-gpio-lines");
534
535 pdevinfo.name = GPIO_MOCKUP_NAME;
536 pdevinfo.id = i;
537 pdevinfo.properties = properties;
538
539 pdev = platform_device_register_full(&pdevinfo);
540 if (IS_ERR(pdev)) {
541 gpio_mockup_err("error registering device");
542 platform_driver_unregister(&gpio_mockup_driver);
543 gpio_mockup_unregister_pdevs();
544 return PTR_ERR(pdev);
545 }
546
547 gpio_mockup_pdevs[i] = pdev;
548 }
549
550 return 0;
551}
552
553static void __exit gpio_mockup_exit(void)
554{
555 debugfs_remove_recursive(gpio_mockup_dbg_dir);
556 platform_driver_unregister(&gpio_mockup_driver);
557 gpio_mockup_unregister_pdevs();
558}
559
560module_init(gpio_mockup_init);
561module_exit(gpio_mockup_exit);
562
563MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
564MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
565MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
566MODULE_DESCRIPTION("GPIO Testing driver");
567MODULE_LICENSE("GPL v2");
568