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/module.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/property.h>
  21 #include <linux/slab.h>
  22 #include <linux/string_helpers.h>
  23 #include <linux/uaccess.h>
  24
  25 #include "gpiolib.h"
  26
  27 #define GPIO_MOCKUP_MAX_GC      10
  28 /*
  29  * We're storing two values per chip: the GPIO base and the number
  30  * of GPIO lines.
  31  */
  32 #define GPIO_MOCKUP_MAX_RANGES  (GPIO_MOCKUP_MAX_GC * 2)
  33 /* Maximum of four properties + the sentinel. */
  34 #define GPIO_MOCKUP_MAX_PROP    5
  35
  36 /*
  37  * struct gpio_pin_status - structure describing a GPIO status
  38  * @dir:       Configures direction of gpio as "in" or "out"
  39  * @value:     Configures status of the gpio as 0(low) or 1(high)
  40  */
  41 struct gpio_mockup_line_status {
  42         int dir;
  43         int value;
  44         int pull;
  45 };
  46
  47 struct gpio_mockup_chip {
  48         struct gpio_chip gc;
  49         struct gpio_mockup_line_status *lines;
  50         struct irq_domain *irq_sim_domain;
  51         struct dentry *dbg_dir;
  52         struct mutex lock;
  53 };
  54
  55 struct gpio_mockup_dbgfs_private {
  56         struct gpio_mockup_chip *chip;
  57         struct gpio_desc *desc;
  58         unsigned int offset;
  59 };
  60
  61 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
  62 static int gpio_mockup_num_ranges;
  63 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
  64
  65 static bool gpio_mockup_named_lines;
  66 module_param_named(gpio_mockup_named_lines,
  67                    gpio_mockup_named_lines, bool, 0400);
  68
  69 static struct dentry *gpio_mockup_dbg_dir;
  70
  71 static int gpio_mockup_range_base(unsigned int index)
  72 {
  73         return gpio_mockup_ranges[index * 2];
  74 }
  75
  76 static int gpio_mockup_range_ngpio(unsigned int index)
  77 {
  78         return gpio_mockup_ranges[index * 2 + 1];
  79 }
  80
  81 static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
  82                              unsigned int offset)
  83 {
  84         return chip->lines[offset].value;
  85 }
  86
  87 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
  88 {
  89         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
  90         int val;
  91
  92         mutex_lock(&chip->lock);
  93         val = __gpio_mockup_get(chip, offset);
  94         mutex_unlock(&chip->lock);
  95
  96         return val;
  97 }
  98
  99 static int gpio_mockup_get_multiple(struct gpio_chip *gc,
 100                                     unsigned long *mask, unsigned long *bits)
 101 {
 102         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 103         unsigned int bit, val;
 104
 105         mutex_lock(&chip->lock);
 106         for_each_set_bit(bit, mask, gc->ngpio) {
 107                 val = __gpio_mockup_get(chip, bit);
 108                 __assign_bit(bit, bits, val);
 109         }
 110         mutex_unlock(&chip->lock);
 111
 112         return 0;
 113 }
 114
 115 static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
 116                               unsigned int offset, int value)
 117 {
 118         chip->lines[offset].value = !!value;
 119 }
 120
 121 static void gpio_mockup_set(struct gpio_chip *gc,
 122                            unsigned int offset, int value)
 123 {
 124         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 125
 126         mutex_lock(&chip->lock);
 127         __gpio_mockup_set(chip, offset, value);
 128         mutex_unlock(&chip->lock);
 129 }
 130
 131 static void gpio_mockup_set_multiple(struct gpio_chip *gc,
 132                                      unsigned long *mask, unsigned long *bits)
 133 {
 134         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 135         unsigned int bit;
 136
 137         mutex_lock(&chip->lock);
 138         for_each_set_bit(bit, mask, gc->ngpio)
 139                 __gpio_mockup_set(chip, bit, test_bit(bit, bits));
 140         mutex_unlock(&chip->lock);
 141 }
 142
 143 static int gpio_mockup_apply_pull(struct gpio_mockup_chip *chip,
 144                                   unsigned int offset, int value)
 145 {
 146         int curr, irq, irq_type, ret = 0;
 147         struct gpio_desc *desc;
 148         struct gpio_chip *gc;
 149
 150         gc = &chip->gc;
 151         desc = &gc->gpiodev->descs[offset];
 152
 153         mutex_lock(&chip->lock);
 154
 155         if (test_bit(FLAG_REQUESTED, &desc->flags) &&
 156             !test_bit(FLAG_IS_OUT, &desc->flags)) {
 157                 curr = __gpio_mockup_get(chip, offset);
 158                 if (curr == value)
 159                         goto out;
 160
 161                 irq = irq_find_mapping(chip->irq_sim_domain, offset);
 162                 if (!irq)
 163                         /*
 164                          * This is fine - it just means, nobody is listening
 165                          * for interrupts on this line, otherwise
 166                          * irq_create_mapping() would have been called from
 167                          * the to_irq() callback.
 168                          */
 169                         goto set_value;
 170
 171                 irq_type = irq_get_trigger_type(irq);
 172
 173                 if ((value == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
 174                     (value == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING))) {
 175                         ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING,
 176                                                     true);
 177                         if (ret)
 178                                 goto out;
 179                 }
 180         }
 181
 182 set_value:
 183         /* Change the value unless we're actively driving the line. */
 184         if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
 185             !test_bit(FLAG_IS_OUT, &desc->flags))
 186                 __gpio_mockup_set(chip, offset, value);
 187
 188 out:
 189         chip->lines[offset].pull = value;
 190         mutex_unlock(&chip->lock);
 191         return ret;
 192 }
 193
 194 static int gpio_mockup_set_config(struct gpio_chip *gc,
 195                                   unsigned int offset, unsigned long config)
 196 {
 197         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 198
 199         switch (pinconf_to_config_param(config)) {
 200         case PIN_CONFIG_BIAS_PULL_UP:
 201                 return gpio_mockup_apply_pull(chip, offset, 1);
 202         case PIN_CONFIG_BIAS_PULL_DOWN:
 203                 return gpio_mockup_apply_pull(chip, offset, 0);
 204         default:
 205                 break;
 206         }
 207         return -ENOTSUPP;
 208 }
 209
 210 static int gpio_mockup_dirout(struct gpio_chip *gc,
 211                               unsigned int offset, int value)
 212 {
 213         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 214
 215         mutex_lock(&chip->lock);
 216         chip->lines[offset].dir = GPIO_LINE_DIRECTION_OUT;
 217         __gpio_mockup_set(chip, offset, value);
 218         mutex_unlock(&chip->lock);
 219
 220         return 0;
 221 }
 222
 223 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
 224 {
 225         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 226
 227         mutex_lock(&chip->lock);
 228         chip->lines[offset].dir = GPIO_LINE_DIRECTION_IN;
 229         mutex_unlock(&chip->lock);
 230
 231         return 0;
 232 }
 233
 234 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
 235 {
 236         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 237         int direction;
 238
 239         mutex_lock(&chip->lock);
 240         direction = chip->lines[offset].dir;
 241         mutex_unlock(&chip->lock);
 242
 243         return direction;
 244 }
 245
 246 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
 247 {
 248         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 249
 250         return irq_create_mapping(chip->irq_sim_domain, offset);
 251 }
 252
 253 static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
 254 {
 255         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 256
 257         __gpio_mockup_set(chip, offset, chip->lines[offset].pull);
 258 }
 259
 260 static ssize_t gpio_mockup_debugfs_read(struct file *file,
 261                                         char __user *usr_buf,
 262                                         size_t size, loff_t *ppos)
 263 {
 264         struct gpio_mockup_dbgfs_private *priv;
 265         struct gpio_mockup_chip *chip;
 266         struct seq_file *sfile;
 267         struct gpio_chip *gc;
 268         int val, cnt;
 269         char buf[3];
 270
 271         if (*ppos != 0)
 272                 return 0;
 273
 274         sfile = file->private_data;
 275         priv = sfile->private;
 276         chip = priv->chip;
 277         gc = &chip->gc;
 278
 279         val = gpio_mockup_get(gc, priv->offset);
 280         cnt = snprintf(buf, sizeof(buf), "%d\n", val);
 281
 282         return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt);
 283 }
 284
 285 static ssize_t gpio_mockup_debugfs_write(struct file *file,
 286                                          const char __user *usr_buf,
 287                                          size_t size, loff_t *ppos)
 288 {
 289         struct gpio_mockup_dbgfs_private *priv;
 290         int rv, val;
 291         struct seq_file *sfile;
 292
 293         if (*ppos != 0)
 294                 return -EINVAL;
 295
 296         rv = kstrtoint_from_user(usr_buf, size, 0, &val);
 297         if (rv)
 298                 return rv;
 299         if (val != 0 && val != 1)
 300                 return -EINVAL;
 301
 302         sfile = file->private_data;
 303         priv = sfile->private;
 304         rv = gpio_mockup_apply_pull(priv->chip, priv->offset, val);
 305         if (rv)
 306                 return rv;
 307
 308         return size;
 309 }
 310
 311 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
 312 {
 313         return single_open(file, NULL, inode->i_private);
 314 }
 315
 316 /*
 317  * Each mockup chip is represented by a directory named after the chip's device
 318  * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
 319  * a file using the line's offset as the name under the chip's directory.
 320  *
 321  * Reading from the line's file yields the current *value*, writing to the
 322  * line's file changes the current *pull*. Default pull for mockup lines is
 323  * down.
 324  *
 325  * Examples:
 326  * - when a line pulled down is requested in output mode and driven high, its
 327  *   value will return to 0 once it's released
 328  * - when the line is requested in output mode and driven high, writing 0 to
 329  *   the corresponding debugfs file will change the pull to down but the
 330  *   reported value will still be 1 until the line is released
 331  * - line requested in input mode always reports the same value as its pull
 332  *   configuration
 333  * - when the line is requested in input mode and monitored for events, writing
 334  *   the same value to the debugfs file will be a noop, while writing the
 335  *   opposite value will generate a dummy interrupt with an appropriate edge
 336  */
 337 static const struct file_operations gpio_mockup_debugfs_ops = {
 338         .owner = THIS_MODULE,
 339         .open = gpio_mockup_debugfs_open,
 340         .read = gpio_mockup_debugfs_read,
 341         .write = gpio_mockup_debugfs_write,
 342         .llseek = no_llseek,
 343         .release = single_release,
 344 };
 345
 346 static void gpio_mockup_debugfs_setup(struct device *dev,
 347                                       struct gpio_mockup_chip *chip)
 348 {
 349         struct gpio_mockup_dbgfs_private *priv;
 350         struct gpio_chip *gc;
 351         const char *devname;
 352         char *name;
 353         int i;
 354
 355         gc = &chip->gc;
 356         devname = dev_name(&gc->gpiodev->dev);
 357
 358         chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
 359
 360         for (i = 0; i < gc->ngpio; i++) {
 361                 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
 362                 if (!name)
 363                         return;
 364
 365                 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 366                 if (!priv)
 367                         return;
 368
 369                 priv->chip = chip;
 370                 priv->offset = i;
 371                 priv->desc = &gc->gpiodev->descs[i];
 372
 373                 debugfs_create_file(name, 0200, chip->dbg_dir, priv,
 374                                     &gpio_mockup_debugfs_ops);
 375         }
 376 }
 377
 378 static void gpio_mockup_dispose_mappings(void *data)
 379 {
 380         struct gpio_mockup_chip *chip = data;
 381         struct gpio_chip *gc = &chip->gc;
 382         int i, irq;
 383
 384         for (i = 0; i < gc->ngpio; i++) {
 385                 irq = irq_find_mapping(chip->irq_sim_domain, i);
 386                 if (irq)
 387                         irq_dispose_mapping(irq);
 388         }
 389 }
 390
 391 static int gpio_mockup_probe(struct platform_device *pdev)
 392 {
 393         struct gpio_mockup_chip *chip;
 394         struct gpio_chip *gc;
 395         struct device *dev;
 396         const char *name;
 397         int rv, base, i;
 398         u16 ngpio;
 399
 400         dev = &pdev->dev;
 401
 402         rv = device_property_read_u32(dev, "gpio-base", &base);
 403         if (rv)
 404                 base = -1;
 405
 406         rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
 407         if (rv)
 408                 return rv;
 409
 410         rv = device_property_read_string(dev, "chip-label", &name);
 411         if (rv)
 412                 name = dev_name(dev);
 413
 414         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 415         if (!chip)
 416                 return -ENOMEM;
 417
 418         mutex_init(&chip->lock);
 419
 420         gc = &chip->gc;
 421         gc->base = base;
 422         gc->ngpio = ngpio;
 423         gc->label = name;
 424         gc->owner = THIS_MODULE;
 425         gc->parent = dev;
 426         gc->get = gpio_mockup_get;
 427         gc->set = gpio_mockup_set;
 428         gc->get_multiple = gpio_mockup_get_multiple;
 429         gc->set_multiple = gpio_mockup_set_multiple;
 430         gc->direction_output = gpio_mockup_dirout;
 431         gc->direction_input = gpio_mockup_dirin;
 432         gc->get_direction = gpio_mockup_get_direction;
 433         gc->set_config = gpio_mockup_set_config;
 434         gc->to_irq = gpio_mockup_to_irq;
 435         gc->free = gpio_mockup_free;
 436
 437         chip->lines = devm_kcalloc(dev, gc->ngpio,
 438                                    sizeof(*chip->lines), GFP_KERNEL);
 439         if (!chip->lines)
 440                 return -ENOMEM;
 441
 442         for (i = 0; i < gc->ngpio; i++)
 443                 chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
 444
 445         chip->irq_sim_domain = devm_irq_domain_create_sim(dev, NULL,
 446                                                           gc->ngpio);
 447         if (IS_ERR(chip->irq_sim_domain))
 448                 return PTR_ERR(chip->irq_sim_domain);
 449
 450         rv = devm_add_action_or_reset(dev, gpio_mockup_dispose_mappings, chip);
 451         if (rv)
 452                 return rv;
 453
 454         rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
 455         if (rv)
 456                 return rv;
 457
 458         gpio_mockup_debugfs_setup(dev, chip);
 459
 460         return 0;
 461 }
 462
 463 static struct platform_driver gpio_mockup_driver = {
 464         .driver = {
 465                 .name = "gpio-mockup",
 466         },
 467         .probe = gpio_mockup_probe,
 468 };
 469
 470 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
 471
 472 static void gpio_mockup_unregister_pdevs(void)
 473 {
 474         struct platform_device *pdev;
 475         int i;
 476
 477         for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
 478                 pdev = gpio_mockup_pdevs[i];
 479
 480                 if (pdev)
 481                         platform_device_unregister(pdev);
 482         }
 483 }
 484
 485 static __init char **gpio_mockup_make_line_names(const char *label,
 486                                                  unsigned int num_lines)
 487 {
 488         unsigned int i;
 489         char **names;
 490
 491         names = kcalloc(num_lines + 1, sizeof(char *), GFP_KERNEL);
 492         if (!names)
 493                 return NULL;
 494
 495         for (i = 0; i < num_lines; i++) {
 496                 names[i] = kasprintf(GFP_KERNEL, "%s-%u", label, i);
 497                 if (!names[i]) {
 498                         kfree_strarray(names, i);
 499                         return NULL;
 500                 }
 501         }
 502
 503         return names;
 504 }
 505
 506 static int __init gpio_mockup_register_chip(int idx)
 507 {
 508         struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
 509         struct platform_device_info pdevinfo;
 510         struct platform_device *pdev;
 511         char **line_names = NULL;
 512         char chip_label[32];
 513         int prop = 0, base;
 514         u16 ngpio;
 515
 516         memset(properties, 0, sizeof(properties));
 517         memset(&pdevinfo, 0, sizeof(pdevinfo));
 518
 519         snprintf(chip_label, sizeof(chip_label), "gpio-mockup-%c", idx + 'A');
 520         properties[prop++] = PROPERTY_ENTRY_STRING("chip-label", chip_label);
 521
 522         base = gpio_mockup_range_base(idx);
 523         if (base >= 0)
 524                 properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", base);
 525
 526         ngpio = base < 0 ? gpio_mockup_range_ngpio(idx)
 527                          : gpio_mockup_range_ngpio(idx) - base;
 528         properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
 529
 530         if (gpio_mockup_named_lines) {
 531                 line_names = gpio_mockup_make_line_names(chip_label, ngpio);
 532                 if (!line_names)
 533                         return -ENOMEM;
 534
 535                 properties[prop++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
 536                                         "gpio-line-names", line_names, ngpio);
 537         }
 538
 539         pdevinfo.name = "gpio-mockup";
 540         pdevinfo.id = idx;
 541         pdevinfo.properties = properties;
 542
 543         pdev = platform_device_register_full(&pdevinfo);
 544         kfree_strarray(line_names, ngpio);
 545         if (IS_ERR(pdev)) {
 546                 pr_err("error registering device");
 547                 return PTR_ERR(pdev);
 548         }
 549
 550         gpio_mockup_pdevs[idx] = pdev;
 551
 552         return 0;
 553 }
 554
 555 static int __init gpio_mockup_init(void)
 556 {
 557         int i, num_chips, err;
 558
 559         if ((gpio_mockup_num_ranges < 2) ||
 560             (gpio_mockup_num_ranges % 2) ||
 561             (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
 562                 return -EINVAL;
 563
 564         /* Each chip is described by two values. */
 565         num_chips = gpio_mockup_num_ranges / 2;
 566
 567         /*
 568          * The second value in the <base GPIO - number of GPIOS> pair must
 569          * always be greater than 0.
 570          */
 571         for (i = 0; i < num_chips; i++) {
 572                 if (gpio_mockup_range_ngpio(i) < 0)
 573                         return -EINVAL;
 574         }
 575
 576         gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
 577
 578         err = platform_driver_register(&gpio_mockup_driver);
 579         if (err) {
 580                 pr_err("error registering platform driver\n");
 581                 debugfs_remove_recursive(gpio_mockup_dbg_dir);
 582                 return err;
 583         }
 584
 585         for (i = 0; i < num_chips; i++) {
 586                 err = gpio_mockup_register_chip(i);
 587                 if (err) {
 588                         platform_driver_unregister(&gpio_mockup_driver);
 589                         gpio_mockup_unregister_pdevs();
 590                         debugfs_remove_recursive(gpio_mockup_dbg_dir);
 591                         return err;
 592                 }
 593         }
 594
 595         return 0;
 596 }
 597
 598 static void __exit gpio_mockup_exit(void)
 599 {
 600         debugfs_remove_recursive(gpio_mockup_dbg_dir);
 601         platform_driver_unregister(&gpio_mockup_driver);
 602         gpio_mockup_unregister_pdevs();
 603 }
 604
 605 module_init(gpio_mockup_init);
 606 module_exit(gpio_mockup_exit);
 607
 608 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
 609 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
 610 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
 611 MODULE_DESCRIPTION("GPIO Testing driver");
 612 MODULE_LICENSE("GPL v2");