1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * GPIO Testing Device Driver
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>
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
29 #define GPIO_MOCKUP_MAX_GC 10
31 * We're storing two values per chip: the GPIO base and the number
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
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
44 * @requested: Request status of this GPIO
46 struct gpio_mockup_line_status {
53 struct gpio_mockup_chip {
55 struct gpio_mockup_line_status *lines;
56 struct irq_domain *irq_sim_domain;
57 struct dentry *dbg_dir;
61 struct gpio_mockup_dbgfs_private {
62 struct gpio_mockup_chip *chip;
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);
70 static bool gpio_mockup_named_lines;
71 module_param_named(gpio_mockup_named_lines,
72 gpio_mockup_named_lines, bool, 0400);
74 static struct dentry *gpio_mockup_dbg_dir;
76 static int gpio_mockup_range_base(unsigned int index)
78 return gpio_mockup_ranges[index * 2];
81 static int gpio_mockup_range_ngpio(unsigned int index)
83 return gpio_mockup_ranges[index * 2 + 1];
86 static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
89 return chip->lines[offset].value;
92 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
94 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
97 scoped_guard(mutex, &chip->lock)
98 val = __gpio_mockup_get(chip, offset);
103 static int gpio_mockup_get_multiple(struct gpio_chip *gc,
104 unsigned long *mask, unsigned long *bits)
106 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
107 unsigned int bit, val;
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);
119 static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
120 unsigned int offset, int value)
122 chip->lines[offset].value = !!value;
125 static void gpio_mockup_set(struct gpio_chip *gc,
126 unsigned int offset, int value)
128 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
130 guard(mutex)(&chip->lock);
132 __gpio_mockup_set(chip, offset, value);
135 static void gpio_mockup_set_multiple(struct gpio_chip *gc,
136 unsigned long *mask, unsigned long *bits)
138 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
141 guard(mutex)(&chip->lock);
143 for_each_set_bit(bit, mask, gc->ngpio)
144 __gpio_mockup_set(chip, bit, test_bit(bit, bits));
147 static int gpio_mockup_apply_pull(struct gpio_mockup_chip *chip,
148 unsigned int offset, int value)
150 struct gpio_mockup_line_status *line = &chip->lines[offset];
151 int curr, irq, irq_type, ret = 0;
153 guard(mutex)(&chip->lock);
155 if (line->requested && line->dir == GPIO_LINE_DIRECTION_IN) {
156 curr = __gpio_mockup_get(chip, offset);
160 irq = irq_find_mapping(chip->irq_sim_domain, offset);
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.
170 irq_type = irq_get_trigger_type(irq);
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,
182 /* Change the value unless we're actively driving the line. */
183 if (!line->requested || line->dir == GPIO_LINE_DIRECTION_IN)
184 __gpio_mockup_set(chip, offset, value);
187 chip->lines[offset].pull = value;
191 static int gpio_mockup_set_config(struct gpio_chip *gc,
192 unsigned int offset, unsigned long config)
194 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
196 switch (pinconf_to_config_param(config)) {
197 case PIN_CONFIG_BIAS_PULL_UP:
198 return gpio_mockup_apply_pull(chip, offset, 1);
199 case PIN_CONFIG_BIAS_PULL_DOWN:
200 return gpio_mockup_apply_pull(chip, offset, 0);
207 static int gpio_mockup_dirout(struct gpio_chip *gc,
208 unsigned int offset, int value)
210 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
212 scoped_guard(mutex, &chip->lock) {
213 chip->lines[offset].dir = GPIO_LINE_DIRECTION_OUT;
214 __gpio_mockup_set(chip, offset, value);
220 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
222 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
224 scoped_guard(mutex, &chip->lock)
225 chip->lines[offset].dir = GPIO_LINE_DIRECTION_IN;
230 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
232 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
235 scoped_guard(mutex, &chip->lock)
236 direction = chip->lines[offset].dir;
241 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
243 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
245 return irq_create_mapping(chip->irq_sim_domain, offset);
248 static int gpio_mockup_request(struct gpio_chip *gc, unsigned int offset)
250 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
252 scoped_guard(mutex, &chip->lock)
253 chip->lines[offset].requested = true;
258 static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
260 struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
262 guard(mutex)(&chip->lock);
264 chip->lines[offset].requested = false;
265 __gpio_mockup_set(chip, offset, chip->lines[offset].pull);
268 static ssize_t gpio_mockup_debugfs_read(struct file *file,
269 char __user *usr_buf,
270 size_t size, loff_t *ppos)
272 struct gpio_mockup_dbgfs_private *priv;
273 struct gpio_mockup_chip *chip;
274 struct seq_file *sfile;
275 struct gpio_chip *gc;
282 sfile = file->private_data;
283 priv = sfile->private;
287 val = gpio_mockup_get(gc, priv->offset);
288 cnt = snprintf(buf, sizeof(buf), "%d\n", val);
290 return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt);
293 static ssize_t gpio_mockup_debugfs_write(struct file *file,
294 const char __user *usr_buf,
295 size_t size, loff_t *ppos)
297 struct gpio_mockup_dbgfs_private *priv;
299 struct seq_file *sfile;
304 rv = kstrtoint_from_user(usr_buf, size, 0, &val);
307 if (val != 0 && val != 1)
310 sfile = file->private_data;
311 priv = sfile->private;
312 rv = gpio_mockup_apply_pull(priv->chip, priv->offset, val);
319 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
321 return single_open(file, NULL, inode->i_private);
325 * Each mockup chip is represented by a directory named after the chip's device
326 * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
327 * a file using the line's offset as the name under the chip's directory.
329 * Reading from the line's file yields the current *value*, writing to the
330 * line's file changes the current *pull*. Default pull for mockup lines is
334 * - when a line pulled down is requested in output mode and driven high, its
335 * value will return to 0 once it's released
336 * - when the line is requested in output mode and driven high, writing 0 to
337 * the corresponding debugfs file will change the pull to down but the
338 * reported value will still be 1 until the line is released
339 * - line requested in input mode always reports the same value as its pull
341 * - when the line is requested in input mode and monitored for events, writing
342 * the same value to the debugfs file will be a noop, while writing the
343 * opposite value will generate a dummy interrupt with an appropriate edge
345 static const struct file_operations gpio_mockup_debugfs_ops = {
346 .owner = THIS_MODULE,
347 .open = gpio_mockup_debugfs_open,
348 .read = gpio_mockup_debugfs_read,
349 .write = gpio_mockup_debugfs_write,
351 .release = single_release,
354 static void gpio_mockup_debugfs_setup(struct device *dev,
355 struct gpio_mockup_chip *chip)
357 struct gpio_mockup_dbgfs_private *priv;
358 struct gpio_chip *gc;
366 * There can only be a single GPIO device per platform device in
367 * gpio-mockup so using device_find_any_child() is OK.
369 struct device *child __free(put_device) = device_find_any_child(dev);
373 devname = dev_name(child);
374 chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
376 for (i = 0; i < gc->ngpio; i++) {
377 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
381 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
388 debugfs_create_file(name, 0600, chip->dbg_dir, priv,
389 &gpio_mockup_debugfs_ops);
393 static void gpio_mockup_debugfs_cleanup(void *data)
395 struct gpio_mockup_chip *chip = data;
397 debugfs_remove_recursive(chip->dbg_dir);
400 static void gpio_mockup_dispose_mappings(void *data)
402 struct gpio_mockup_chip *chip = data;
403 struct gpio_chip *gc = &chip->gc;
406 for (i = 0; i < gc->ngpio; i++) {
407 irq = irq_find_mapping(chip->irq_sim_domain, i);
409 irq_dispose_mapping(irq);
413 static int gpio_mockup_probe(struct platform_device *pdev)
415 struct gpio_mockup_chip *chip;
416 struct gpio_chip *gc;
424 rv = device_property_read_u32(dev, "gpio-base", &base);
428 rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
432 rv = device_property_read_string(dev, "chip-label", &name);
434 name = dev_name(dev);
436 chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
440 mutex_init(&chip->lock);
446 gc->owner = THIS_MODULE;
448 gc->get = gpio_mockup_get;
449 gc->set = gpio_mockup_set;
450 gc->get_multiple = gpio_mockup_get_multiple;
451 gc->set_multiple = gpio_mockup_set_multiple;
452 gc->direction_output = gpio_mockup_dirout;
453 gc->direction_input = gpio_mockup_dirin;
454 gc->get_direction = gpio_mockup_get_direction;
455 gc->set_config = gpio_mockup_set_config;
456 gc->to_irq = gpio_mockup_to_irq;
457 gc->request = gpio_mockup_request;
458 gc->free = gpio_mockup_free;
460 chip->lines = devm_kcalloc(dev, gc->ngpio,
461 sizeof(*chip->lines), GFP_KERNEL);
465 for (i = 0; i < gc->ngpio; i++)
466 chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
468 chip->irq_sim_domain = devm_irq_domain_create_sim(dev, NULL,
470 if (IS_ERR(chip->irq_sim_domain))
471 return PTR_ERR(chip->irq_sim_domain);
473 rv = devm_add_action_or_reset(dev, gpio_mockup_dispose_mappings, chip);
477 rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
481 gpio_mockup_debugfs_setup(dev, chip);
483 return devm_add_action_or_reset(dev, gpio_mockup_debugfs_cleanup, chip);
486 static const struct of_device_id gpio_mockup_of_match[] = {
487 { .compatible = "gpio-mockup", },
490 MODULE_DEVICE_TABLE(of, gpio_mockup_of_match);
492 static struct platform_driver gpio_mockup_driver = {
494 .name = "gpio-mockup",
495 .of_match_table = gpio_mockup_of_match,
497 .probe = gpio_mockup_probe,
500 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
502 static void gpio_mockup_unregister_pdevs(void)
504 struct platform_device *pdev;
505 struct fwnode_handle *fwnode;
508 for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
509 pdev = gpio_mockup_pdevs[i];
513 fwnode = dev_fwnode(&pdev->dev);
514 platform_device_unregister(pdev);
515 fwnode_remove_software_node(fwnode);
519 static int __init gpio_mockup_register_chip(int idx)
521 struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
522 struct platform_device_info pdevinfo;
523 struct platform_device *pdev;
524 struct fwnode_handle *fwnode;
525 char **line_names = NULL;
530 memset(properties, 0, sizeof(properties));
531 memset(&pdevinfo, 0, sizeof(pdevinfo));
533 snprintf(chip_label, sizeof(chip_label), "gpio-mockup-%c", idx + 'A');
534 properties[prop++] = PROPERTY_ENTRY_STRING("chip-label", chip_label);
536 base = gpio_mockup_range_base(idx);
538 properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", base);
540 ngpio = base < 0 ? gpio_mockup_range_ngpio(idx)
541 : gpio_mockup_range_ngpio(idx) - base;
542 properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
544 if (gpio_mockup_named_lines) {
545 line_names = kasprintf_strarray(GFP_KERNEL, chip_label, ngpio);
549 properties[prop++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
550 "gpio-line-names", line_names, ngpio);
553 fwnode = fwnode_create_software_node(properties, NULL);
554 if (IS_ERR(fwnode)) {
555 kfree_strarray(line_names, ngpio);
556 return PTR_ERR(fwnode);
559 pdevinfo.name = "gpio-mockup";
561 pdevinfo.fwnode = fwnode;
563 pdev = platform_device_register_full(&pdevinfo);
564 kfree_strarray(line_names, ngpio);
566 fwnode_remove_software_node(fwnode);
567 pr_err("error registering device");
568 return PTR_ERR(pdev);
571 gpio_mockup_pdevs[idx] = pdev;
576 static int __init gpio_mockup_init(void)
578 int i, num_chips, err;
580 if ((gpio_mockup_num_ranges % 2) ||
581 (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
584 /* Each chip is described by two values. */
585 num_chips = gpio_mockup_num_ranges / 2;
588 * The second value in the <base GPIO - number of GPIOS> pair must
589 * always be greater than 0.
591 for (i = 0; i < num_chips; i++) {
592 if (gpio_mockup_range_ngpio(i) < 0)
596 gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
598 err = platform_driver_register(&gpio_mockup_driver);
600 pr_err("error registering platform driver\n");
601 debugfs_remove_recursive(gpio_mockup_dbg_dir);
605 for (i = 0; i < num_chips; i++) {
606 err = gpio_mockup_register_chip(i);
608 platform_driver_unregister(&gpio_mockup_driver);
609 gpio_mockup_unregister_pdevs();
610 debugfs_remove_recursive(gpio_mockup_dbg_dir);
618 static void __exit gpio_mockup_exit(void)
620 gpio_mockup_unregister_pdevs();
621 debugfs_remove_recursive(gpio_mockup_dbg_dir);
622 platform_driver_unregister(&gpio_mockup_driver);
625 module_init(gpio_mockup_init);
626 module_exit(gpio_mockup_exit);
628 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
629 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
630 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
631 MODULE_DESCRIPTION("GPIO Testing driver");
632 MODULE_LICENSE("GPL v2");