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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 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
224static 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
273out:
274 chip->lines[priv->offset].pull = val;
275 mutex_unlock(&chip->lock);
276
277 return size;
278}
279
280static 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 */
306static 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 .release = single_release,
313};
314
315static void gpio_mockup_debugfs_setup(struct device *dev,
316 struct gpio_mockup_chip *chip)
317{
318 struct gpio_mockup_dbgfs_private *priv;
319 struct gpio_chip *gc;
320 const char *devname;
321 char *name;
322 int i;
323
324 gc = &chip->gc;
325 devname = dev_name(&gc->gpiodev->dev);
326
327 chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
328
329 for (i = 0; i < gc->ngpio; i++) {
330 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
331 if (!name)
332 return;
333
334 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
335 if (!priv)
336 return;
337
338 priv->chip = chip;
339 priv->offset = i;
340 priv->desc = &gc->gpiodev->descs[i];
341
342 debugfs_create_file(name, 0200, chip->dbg_dir, priv,
343 &gpio_mockup_debugfs_ops);
344 }
345
346 return;
347}
348
349static int gpio_mockup_name_lines(struct device *dev,
350 struct gpio_mockup_chip *chip)
351{
352 struct gpio_chip *gc = &chip->gc;
353 char **names;
354 int i;
355
356 names = devm_kcalloc(dev, gc->ngpio, sizeof(char *), GFP_KERNEL);
357 if (!names)
358 return -ENOMEM;
359
360 for (i = 0; i < gc->ngpio; i++) {
361 names[i] = devm_kasprintf(dev, GFP_KERNEL,
362 "%s-%d", gc->label, i);
363 if (!names[i])
364 return -ENOMEM;
365 }
366
367 gc->names = (const char *const *)names;
368
369 return 0;
370}
371
372static int gpio_mockup_probe(struct platform_device *pdev)
373{
374 struct gpio_mockup_chip *chip;
375 struct gpio_chip *gc;
376 struct device *dev;
377 const char *name;
378 int rv, base;
379 u16 ngpio;
380
381 dev = &pdev->dev;
382
383 rv = device_property_read_u32(dev, "gpio-base", &base);
384 if (rv)
385 base = -1;
386
387 rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
388 if (rv)
389 return rv;
390
391 rv = device_property_read_string(dev, "chip-name", &name);
392 if (rv)
393 name = NULL;
394
395 chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
396 if (!chip)
397 return -ENOMEM;
398
399 if (!name) {
400 name = devm_kasprintf(dev, GFP_KERNEL,
401 "%s-%c", pdev->name, pdev->id + 'A');
402 if (!name)
403 return -ENOMEM;
404 }
405
406 mutex_init(&chip->lock);
407
408 gc = &chip->gc;
409 gc->base = base;
410 gc->ngpio = ngpio;
411 gc->label = name;
412 gc->owner = THIS_MODULE;
413 gc->parent = dev;
414 gc->get = gpio_mockup_get;
415 gc->set = gpio_mockup_set;
416 gc->get_multiple = gpio_mockup_get_multiple;
417 gc->set_multiple = gpio_mockup_set_multiple;
418 gc->direction_output = gpio_mockup_dirout;
419 gc->direction_input = gpio_mockup_dirin;
420 gc->get_direction = gpio_mockup_get_direction;
421 gc->to_irq = gpio_mockup_to_irq;
422 gc->free = gpio_mockup_free;
423
424 chip->lines = devm_kcalloc(dev, gc->ngpio,
425 sizeof(*chip->lines), GFP_KERNEL);
426 if (!chip->lines)
427 return -ENOMEM;
428
429 if (device_property_read_bool(dev, "named-gpio-lines")) {
430 rv = gpio_mockup_name_lines(dev, chip);
431 if (rv)
432 return rv;
433 }
434
435 rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio);
436 if (rv < 0)
437 return rv;
438
439 rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
440 if (rv)
441 return rv;
442
443 gpio_mockup_debugfs_setup(dev, chip);
444
445 return 0;
446}
447
448static struct platform_driver gpio_mockup_driver = {
449 .driver = {
450 .name = GPIO_MOCKUP_NAME,
451 },
452 .probe = gpio_mockup_probe,
453};
454
455static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
456
457static void gpio_mockup_unregister_pdevs(void)
458{
459 struct platform_device *pdev;
460 int i;
461
462 for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
463 pdev = gpio_mockup_pdevs[i];
464
465 if (pdev)
466 platform_device_unregister(pdev);
467 }
468}
469
470static int __init gpio_mockup_init(void)
471{
472 struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
473 int i, prop, num_chips, err = 0, base;
474 struct platform_device_info pdevinfo;
475 struct platform_device *pdev;
476 u16 ngpio;
477
478 if ((gpio_mockup_num_ranges < 2) ||
479 (gpio_mockup_num_ranges % 2) ||
480 (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
481 return -EINVAL;
482
483 /* Each chip is described by two values. */
484 num_chips = gpio_mockup_num_ranges / 2;
485
486 /*
487 * The second value in the <base GPIO - number of GPIOS> pair must
488 * always be greater than 0.
489 */
490 for (i = 0; i < num_chips; i++) {
491 if (gpio_mockup_range_ngpio(i) < 0)
492 return -EINVAL;
493 }
494
495 gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
496
497 err = platform_driver_register(&gpio_mockup_driver);
498 if (err) {
499 gpio_mockup_err("error registering platform driver\n");
500 return err;
501 }
502
503 for (i = 0; i < num_chips; i++) {
504 memset(properties, 0, sizeof(properties));
505 memset(&pdevinfo, 0, sizeof(pdevinfo));
506 prop = 0;
507
508 base = gpio_mockup_range_base(i);
509 if (base >= 0)
510 properties[prop++] = PROPERTY_ENTRY_U32("gpio-base",
511 base);
512
513 ngpio = base < 0 ? gpio_mockup_range_ngpio(i)
514 : gpio_mockup_range_ngpio(i) - base;
515 properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
516
517 if (gpio_mockup_named_lines)
518 properties[prop++] = PROPERTY_ENTRY_BOOL(
519 "named-gpio-lines");
520
521 pdevinfo.name = GPIO_MOCKUP_NAME;
522 pdevinfo.id = i;
523 pdevinfo.properties = properties;
524
525 pdev = platform_device_register_full(&pdevinfo);
526 if (IS_ERR(pdev)) {
527 gpio_mockup_err("error registering device");
528 platform_driver_unregister(&gpio_mockup_driver);
529 gpio_mockup_unregister_pdevs();
530 return PTR_ERR(pdev);
531 }
532
533 gpio_mockup_pdevs[i] = pdev;
534 }
535
536 return 0;
537}
538
539static void __exit gpio_mockup_exit(void)
540{
541 debugfs_remove_recursive(gpio_mockup_dbg_dir);
542 platform_driver_unregister(&gpio_mockup_driver);
543 gpio_mockup_unregister_pdevs();
544}
545
546module_init(gpio_mockup_init);
547module_exit(gpio_mockup_exit);
548
549MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
550MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
551MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
552MODULE_DESCRIPTION("GPIO Testing driver");
553MODULE_LICENSE("GPL v2");