drivers/gpio/gpio-mockup.c

   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/slab.h>
  23 #include <linux/string_helpers.h>
  24 #include <linux/uaccess.h>
  25
  26 #include "gpiolib.h"
  27
  28 #define GPIO_MOCKUP_MAX_GC      10
  29 /*
  30  * We're storing two values per chip: the GPIO base and the number
  31  * of GPIO lines.
  32  */
  33 #define GPIO_MOCKUP_MAX_RANGES  (GPIO_MOCKUP_MAX_GC * 2)
  34 /* Maximum of four properties + the sentinel. */
  35 #define GPIO_MOCKUP_MAX_PROP    5
  36
  37 /*
  38  * struct gpio_pin_status - structure describing a GPIO status
  39  * @dir:       Configures direction of gpio as "in" or "out"
  40  * @value:     Configures status of the gpio as 0(low) or 1(high)
  41  */
  42 struct gpio_mockup_line_status {
  43         int dir;
  44         int value;
  45         int pull;
  46 };
  47
  48 struct gpio_mockup_chip {
  49         struct gpio_chip gc;
  50         struct gpio_mockup_line_status *lines;
  51         struct irq_domain *irq_sim_domain;
  52         struct dentry *dbg_dir;
  53         struct mutex lock;
  54 };
  55
  56 struct gpio_mockup_dbgfs_private {
  57         struct gpio_mockup_chip *chip;
  58         struct gpio_desc *desc;
  59         unsigned int offset;
  60 };
  61
  62 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
  63 static int gpio_mockup_num_ranges;
  64 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
  65
  66 static bool gpio_mockup_named_lines;
  67 module_param_named(gpio_mockup_named_lines,
  68                    gpio_mockup_named_lines, bool, 0400);
  69
  70 static struct dentry *gpio_mockup_dbg_dir;
  71
  72 static int gpio_mockup_range_base(unsigned int index)
  73 {
  74         return gpio_mockup_ranges[index * 2];
  75 }
  76
  77 static int gpio_mockup_range_ngpio(unsigned int index)
  78 {
  79         return gpio_mockup_ranges[index * 2 + 1];
  80 }
  81
  82 static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
  83                              unsigned int offset)
  84 {
  85         return chip->lines[offset].value;
  86 }
  87
  88 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
  89 {
  90         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
  91         int val;
  92
  93         mutex_lock(&chip->lock);
  94         val = __gpio_mockup_get(chip, offset);
  95         mutex_unlock(&chip->lock);
  96
  97         return val;
  98 }
  99
 100 static int gpio_mockup_get_multiple(struct gpio_chip *gc,
 101                                     unsigned long *mask, unsigned long *bits)
 102 {
 103         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 104         unsigned int bit, val;
 105
 106         mutex_lock(&chip->lock);
 107         for_each_set_bit(bit, mask, gc->ngpio) {
 108                 val = __gpio_mockup_get(chip, bit);
 109                 __assign_bit(bit, bits, val);
 110         }
 111         mutex_unlock(&chip->lock);
 112
 113         return 0;
 114 }
 115
 116 static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
 117                               unsigned int offset, int value)
 118 {
 119         chip->lines[offset].value = !!value;
 120 }
 121
 122 static void gpio_mockup_set(struct gpio_chip *gc,
 123                            unsigned int offset, int value)
 124 {
 125         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 126
 127         mutex_lock(&chip->lock);
 128         __gpio_mockup_set(chip, offset, value);
 129         mutex_unlock(&chip->lock);
 130 }
 131
 132 static void gpio_mockup_set_multiple(struct gpio_chip *gc,
 133                                      unsigned long *mask, unsigned long *bits)
 134 {
 135         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 136         unsigned int bit;
 137
 138         mutex_lock(&chip->lock);
 139         for_each_set_bit(bit, mask, gc->ngpio)
 140                 __gpio_mockup_set(chip, bit, test_bit(bit, bits));
 141         mutex_unlock(&chip->lock);
 142 }
 143
 144 static int gpio_mockup_apply_pull(struct gpio_mockup_chip *chip,
 145                                   unsigned int offset, int value)
 146 {
 147         int curr, irq, irq_type, ret = 0;
 148         struct gpio_desc *desc;
 149         struct gpio_chip *gc;
 150
 151         gc = &chip->gc;
 152         desc = &gc->gpiodev->descs[offset];
 153
 154         mutex_lock(&chip->lock);
 155
 156         if (test_bit(FLAG_REQUESTED, &desc->flags) &&
 157             !test_bit(FLAG_IS_OUT, &desc->flags)) {
 158                 curr = __gpio_mockup_get(chip, offset);
 159                 if (curr == value)
 160                         goto out;
 161
 162                 irq = irq_find_mapping(chip->irq_sim_domain, offset);
 163                 if (!irq)
 164                         /*
 165                          * This is fine - it just means, nobody is listening
 166                          * for interrupts on this line, otherwise
 167                          * irq_create_mapping() would have been called from
 168                          * the to_irq() callback.
 169                          */
 170                         goto set_value;
 171
 172                 irq_type = irq_get_trigger_type(irq);
 173
 174                 if ((value == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
 175                     (value == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING))) {
 176                         ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING,
 177                                                     true);
 178                         if (ret)
 179                                 goto out;
 180                 }
 181         }
 182
 183 set_value:
 184         /* Change the value unless we're actively driving the line. */
 185         if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
 186             !test_bit(FLAG_IS_OUT, &desc->flags))
 187                 __gpio_mockup_set(chip, offset, value);
 188
 189 out:
 190         chip->lines[offset].pull = value;
 191         mutex_unlock(&chip->lock);
 192         return ret;
 193 }
 194
 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
 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         mutex_lock(&chip->lock);
 217         chip->lines[offset].dir = GPIO_LINE_DIRECTION_OUT;
 218         __gpio_mockup_set(chip, offset, value);
 219         mutex_unlock(&chip->lock);
 220
 221         return 0;
 222 }
 223
 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         mutex_lock(&chip->lock);
 229         chip->lines[offset].dir = GPIO_LINE_DIRECTION_IN;
 230         mutex_unlock(&chip->lock);
 231
 232         return 0;
 233 }
 234
 235 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
 236 {
 237         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 238         int direction;
 239
 240         mutex_lock(&chip->lock);
 241         direction = chip->lines[offset].dir;
 242         mutex_unlock(&chip->lock);
 243
 244         return direction;
 245 }
 246
 247 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
 248 {
 249         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 250
 251         return irq_create_mapping(chip->irq_sim_domain, offset);
 252 }
 253
 254 static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
 255 {
 256         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 257
 258         __gpio_mockup_set(chip, offset, chip->lines[offset].pull);
 259 }
 260
 261 static ssize_t gpio_mockup_debugfs_read(struct file *file,
 262                                         char __user *usr_buf,
 263                                         size_t size, loff_t *ppos)
 264 {
 265         struct gpio_mockup_dbgfs_private *priv;
 266         struct gpio_mockup_chip *chip;
 267         struct seq_file *sfile;
 268         struct gpio_chip *gc;
 269         int val, cnt;
 270         char buf[3];
 271
 272         if (*ppos != 0)
 273                 return 0;
 274
 275         sfile = file->private_data;
 276         priv = sfile->private;
 277         chip = priv->chip;
 278         gc = &chip->gc;
 279
 280         val = gpio_mockup_get(gc, priv->offset);
 281         cnt = snprintf(buf, sizeof(buf), "%d\n", val);
 282
 283         return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt);
 284 }
 285
 286 static ssize_t gpio_mockup_debugfs_write(struct file *file,
 287                                          const char __user *usr_buf,
 288                                          size_t size, loff_t *ppos)
 289 {
 290         struct gpio_mockup_dbgfs_private *priv;
 291         int rv, val;
 292         struct seq_file *sfile;
 293
 294         if (*ppos != 0)
 295                 return -EINVAL;
 296
 297         rv = kstrtoint_from_user(usr_buf, size, 0, &val);
 298         if (rv)
 299                 return rv;
 300         if (val != 0 && val != 1)
 301                 return -EINVAL;
 302
 303         sfile = file->private_data;
 304         priv = sfile->private;
 305         rv = gpio_mockup_apply_pull(priv->chip, priv->offset, val);
 306         if (rv)
 307                 return rv;
 308
 309         return size;
 310 }
 311
 312 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
 313 {
 314         return single_open(file, NULL, inode->i_private);
 315 }
 316
 317 /*
 318  * Each mockup chip is represented by a directory named after the chip's device
 319  * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
 320  * a file using the line's offset as the name under the chip's directory.
 321  *
 322  * Reading from the line's file yields the current *value*, writing to the
 323  * line's file changes the current *pull*. Default pull for mockup lines is
 324  * down.
 325  *
 326  * Examples:
 327  * - when a line pulled down is requested in output mode and driven high, its
 328  *   value will return to 0 once it's released
 329  * - when the line is requested in output mode and driven high, writing 0 to
 330  *   the corresponding debugfs file will change the pull to down but the
 331  *   reported value will still be 1 until the line is released
 332  * - line requested in input mode always reports the same value as its pull
 333  *   configuration
 334  * - when the line is requested in input mode and monitored for events, writing
 335  *   the same value to the debugfs file will be a noop, while writing the
 336  *   opposite value will generate a dummy interrupt with an appropriate edge
 337  */
 338 static const struct file_operations gpio_mockup_debugfs_ops = {
 339         .owner = THIS_MODULE,
 340         .open = gpio_mockup_debugfs_open,
 341         .read = gpio_mockup_debugfs_read,
 342         .write = gpio_mockup_debugfs_write,
 343         .llseek = no_llseek,
 344         .release = single_release,
 345 };
 346
 347 static void gpio_mockup_debugfs_setup(struct device *dev,
 348                                       struct gpio_mockup_chip *chip)
 349 {
 350         struct gpio_mockup_dbgfs_private *priv;
 351         struct gpio_chip *gc;
 352         const char *devname;
 353         char *name;
 354         int i;
 355
 356         gc = &chip->gc;
 357         devname = dev_name(&gc->gpiodev->dev);
 358
 359         chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
 360
 361         for (i = 0; i < gc->ngpio; i++) {
 362                 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
 363                 if (!name)
 364                         return;
 365
 366                 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 367                 if (!priv)
 368                         return;
 369
 370                 priv->chip = chip;
 371                 priv->offset = i;
 372                 priv->desc = &gc->gpiodev->descs[i];
 373
 374                 debugfs_create_file(name, 0200, chip->dbg_dir, priv,
 375                                     &gpio_mockup_debugfs_ops);
 376         }
 377 }
 378
 379 static void gpio_mockup_dispose_mappings(void *data)
 380 {
 381         struct gpio_mockup_chip *chip = data;
 382         struct gpio_chip *gc = &chip->gc;
 383         int i, irq;
 384
 385         for (i = 0; i < gc->ngpio; i++) {
 386                 irq = irq_find_mapping(chip->irq_sim_domain, i);
 387                 if (irq)
 388                         irq_dispose_mapping(irq);
 389         }
 390 }
 391
 392 static int gpio_mockup_probe(struct platform_device *pdev)
 393 {
 394         struct gpio_mockup_chip *chip;
 395         struct gpio_chip *gc;
 396         struct device *dev;
 397         const char *name;
 398         int rv, base, i;
 399         u16 ngpio;
 400
 401         dev = &pdev->dev;
 402
 403         rv = device_property_read_u32(dev, "gpio-base", &base);
 404         if (rv)
 405                 base = -1;
 406
 407         rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
 408         if (rv)
 409                 return rv;
 410
 411         rv = device_property_read_string(dev, "chip-label", &name);
 412         if (rv)
 413                 name = dev_name(dev);
 414
 415         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 416         if (!chip)
 417                 return -ENOMEM;
 418
 419         mutex_init(&chip->lock);
 420
 421         gc = &chip->gc;
 422         gc->base = base;
 423         gc->ngpio = ngpio;
 424         gc->label = name;
 425         gc->owner = THIS_MODULE;
 426         gc->parent = dev;
 427         gc->get = gpio_mockup_get;
 428         gc->set = gpio_mockup_set;
 429         gc->get_multiple = gpio_mockup_get_multiple;
 430         gc->set_multiple = gpio_mockup_set_multiple;
 431         gc->direction_output = gpio_mockup_dirout;
 432         gc->direction_input = gpio_mockup_dirin;
 433         gc->get_direction = gpio_mockup_get_direction;
 434         gc->set_config = gpio_mockup_set_config;
 435         gc->to_irq = gpio_mockup_to_irq;
 436         gc->free = gpio_mockup_free;
 437
 438         chip->lines = devm_kcalloc(dev, gc->ngpio,
 439                                    sizeof(*chip->lines), GFP_KERNEL);
 440         if (!chip->lines)
 441                 return -ENOMEM;
 442
 443         for (i = 0; i < gc->ngpio; i++)
 444                 chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
 445
 446         chip->irq_sim_domain = devm_irq_domain_create_sim(dev, NULL,
 447                                                           gc->ngpio);
 448         if (IS_ERR(chip->irq_sim_domain))
 449                 return PTR_ERR(chip->irq_sim_domain);
 450
 451         rv = devm_add_action_or_reset(dev, gpio_mockup_dispose_mappings, chip);
 452         if (rv)
 453                 return rv;
 454
 455         rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
 456         if (rv)
 457                 return rv;
 458
 459         gpio_mockup_debugfs_setup(dev, chip);
 460
 461         return 0;
 462 }
 463
 464 static const struct of_device_id gpio_mockup_of_match[] = {
 465         { .compatible = "gpio-mockup", },
 466         {},
 467 };
 468 MODULE_DEVICE_TABLE(of, gpio_mockup_of_match);
 469
 470 static struct platform_driver gpio_mockup_driver = {
 471         .driver = {
 472                 .name = "gpio-mockup",
 473                 .of_match_table = gpio_mockup_of_match,
 474         },
 475         .probe = gpio_mockup_probe,
 476 };
 477
 478 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
 479
 480 static void gpio_mockup_unregister_pdevs(void)
 481 {
 482         struct platform_device *pdev;
 483         int i;
 484
 485         for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
 486                 pdev = gpio_mockup_pdevs[i];
 487
 488                 if (pdev)
 489                         platform_device_unregister(pdev);
 490         }
 491 }
 492
 493 static __init char **gpio_mockup_make_line_names(const char *label,
 494                                                  unsigned int num_lines)
 495 {
 496         unsigned int i;
 497         char **names;
 498
 499         names = kcalloc(num_lines + 1, sizeof(char *), GFP_KERNEL);
 500         if (!names)
 501                 return NULL;
 502
 503         for (i = 0; i < num_lines; i++) {
 504                 names[i] = kasprintf(GFP_KERNEL, "%s-%u", label, i);
 505                 if (!names[i]) {
 506                         kfree_strarray(names, i);
 507                         return NULL;
 508                 }
 509         }
 510
 511         return names;
 512 }
 513
 514 static int __init gpio_mockup_register_chip(int idx)
 515 {
 516         struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
 517         struct platform_device_info pdevinfo;
 518         struct platform_device *pdev;
 519         char **line_names = NULL;
 520         char chip_label[32];
 521         int prop = 0, base;
 522         u16 ngpio;
 523
 524         memset(properties, 0, sizeof(properties));
 525         memset(&pdevinfo, 0, sizeof(pdevinfo));
 526
 527         snprintf(chip_label, sizeof(chip_label), "gpio-mockup-%c", idx + 'A');
 528         properties[prop++] = PROPERTY_ENTRY_STRING("chip-label", chip_label);
 529
 530         base = gpio_mockup_range_base(idx);
 531         if (base >= 0)
 532                 properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", base);
 533
 534         ngpio = base < 0 ? gpio_mockup_range_ngpio(idx)
 535                          : gpio_mockup_range_ngpio(idx) - base;
 536         properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
 537
 538         if (gpio_mockup_named_lines) {
 539                 line_names = gpio_mockup_make_line_names(chip_label, ngpio);
 540                 if (!line_names)
 541                         return -ENOMEM;
 542
 543                 properties[prop++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
 544                                         "gpio-line-names", line_names, ngpio);
 545         }
 546
 547         pdevinfo.name = "gpio-mockup";
 548         pdevinfo.id = idx;
 549         pdevinfo.properties = properties;
 550
 551         pdev = platform_device_register_full(&pdevinfo);
 552         kfree_strarray(line_names, ngpio);
 553         if (IS_ERR(pdev)) {
 554                 pr_err("error registering device");
 555                 return PTR_ERR(pdev);
 556         }
 557
 558         gpio_mockup_pdevs[idx] = pdev;
 559
 560         return 0;
 561 }
 562
 563 static int __init gpio_mockup_init(void)
 564 {
 565         int i, num_chips, err;
 566
 567         if ((gpio_mockup_num_ranges % 2) ||
 568             (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
 569                 return -EINVAL;
 570
 571         /* Each chip is described by two values. */
 572         num_chips = gpio_mockup_num_ranges / 2;
 573
 574         /*
 575          * The second value in the <base GPIO - number of GPIOS> pair must
 576          * always be greater than 0.
 577          */
 578         for (i = 0; i < num_chips; i++) {
 579                 if (gpio_mockup_range_ngpio(i) < 0)
 580                         return -EINVAL;
 581         }
 582
 583         gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
 584
 585         err = platform_driver_register(&gpio_mockup_driver);
 586         if (err) {
 587                 pr_err("error registering platform driver\n");
 588                 debugfs_remove_recursive(gpio_mockup_dbg_dir);
 589                 return err;
 590         }
 591
 592         for (i = 0; i < num_chips; i++) {
 593                 err = gpio_mockup_register_chip(i);
 594                 if (err) {
 595                         platform_driver_unregister(&gpio_mockup_driver);
 596                         gpio_mockup_unregister_pdevs();
 597                         debugfs_remove_recursive(gpio_mockup_dbg_dir);
 598                         return err;
 599                 }
 600         }
 601
 602         return 0;
 603 }
 604
 605 static void __exit gpio_mockup_exit(void)
 606 {
 607         debugfs_remove_recursive(gpio_mockup_dbg_dir);
 608         platform_driver_unregister(&gpio_mockup_driver);
 609         gpio_mockup_unregister_pdevs();
 610 }
 611
 612 module_init(gpio_mockup_init);
 613 module_exit(gpio_mockup_exit);
 614
 615 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
 616 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
 617 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
 618 MODULE_DESCRIPTION("GPIO Testing driver");
 619 MODULE_LICENSE("GPL v2");