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/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>
  28
  29 #define GPIO_MOCKUP_MAX_GC      10
  30 /*
  31  * We're storing two values per chip: the GPIO base and the number
  32  * of GPIO lines.
  33  */
  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
  37
  38 /*
  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
  43  *             1 (pull-up)
  44  * @requested: Request status of this GPIO
  45  */
  46 struct gpio_mockup_line_status {
  47         int dir;
  48         int value;
  49         int pull;
  50         bool requested;
  51 };
  52
  53 struct gpio_mockup_chip {
  54         struct gpio_chip gc;
  55         struct gpio_mockup_line_status *lines;
  56         struct irq_domain *irq_sim_domain;
  57         struct dentry *dbg_dir;
  58         struct mutex lock;
  59 };
  60
  61 struct gpio_mockup_dbgfs_private {
  62         struct gpio_mockup_chip *chip;
  63         unsigned int offset;
  64 };
  65
  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);
  69
  70 static bool gpio_mockup_named_lines;
  71 module_param_named(gpio_mockup_named_lines,
  72                    gpio_mockup_named_lines, bool, 0400);
  73
  74 static struct dentry *gpio_mockup_dbg_dir;
  75
  76 static int gpio_mockup_range_base(unsigned int index)
  77 {
  78         return gpio_mockup_ranges[index * 2];
  79 }
  80
  81 static int gpio_mockup_range_ngpio(unsigned int index)
  82 {
  83         return gpio_mockup_ranges[index * 2 + 1];
  84 }
  85
  86 static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
  87                              unsigned int offset)
  88 {
  89         return chip->lines[offset].value;
  90 }
  91
  92 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
  93 {
  94         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
  95         int val;
  96
  97         scoped_guard(mutex, &chip->lock)
  98                 val = __gpio_mockup_get(chip, offset);
  99
 100         return val;
 101 }
 102
 103 static int gpio_mockup_get_multiple(struct gpio_chip *gc,
 104                                     unsigned long *mask, unsigned long *bits)
 105 {
 106         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 107         unsigned int bit, val;
 108
 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);
 113                 }
 114         }
 115
 116         return 0;
 117 }
 118
 119 static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
 120                               unsigned int offset, int value)
 121 {
 122         chip->lines[offset].value = !!value;
 123 }
 124
 125 static void gpio_mockup_set(struct gpio_chip *gc,
 126                            unsigned int offset, int value)
 127 {
 128         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 129
 130         guard(mutex)(&chip->lock);
 131
 132         __gpio_mockup_set(chip, offset, value);
 133 }
 134
 135 static void gpio_mockup_set_multiple(struct gpio_chip *gc,
 136                                      unsigned long *mask, unsigned long *bits)
 137 {
 138         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 139         unsigned int bit;
 140
 141         guard(mutex)(&chip->lock);
 142
 143         for_each_set_bit(bit, mask, gc->ngpio)
 144                 __gpio_mockup_set(chip, bit, test_bit(bit, bits));
 145 }
 146
 147 static int gpio_mockup_apply_pull(struct gpio_mockup_chip *chip,
 148                                   unsigned int offset, int value)
 149 {
 150         struct gpio_mockup_line_status *line = &chip->lines[offset];
 151         int curr, irq, irq_type, ret = 0;
 152
 153         guard(mutex)(&chip->lock);
 154
 155         if (line->requested && line->dir == GPIO_LINE_DIRECTION_IN) {
 156                 curr = __gpio_mockup_get(chip, offset);
 157                 if (curr == value)
 158                         goto out;
 159
 160                 irq = irq_find_mapping(chip->irq_sim_domain, offset);
 161                 if (!irq)
 162                         /*
 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.
 167                          */
 168                         goto set_value;
 169
 170                 irq_type = irq_get_trigger_type(irq);
 171
 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,
 175                                                     true);
 176                         if (ret)
 177                                 goto out;
 178                 }
 179         }
 180
 181 set_value:
 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);
 185
 186 out:
 187         chip->lines[offset].pull = value;
 188         return ret;
 189 }
 190
 191 static int gpio_mockup_set_config(struct gpio_chip *gc,
 192                                   unsigned int offset, unsigned long config)
 193 {
 194         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 195
 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);
 201         default:
 202                 break;
 203         }
 204         return -ENOTSUPP;
 205 }
 206
 207 static int gpio_mockup_dirout(struct gpio_chip *gc,
 208                               unsigned int offset, int value)
 209 {
 210         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 211
 212         scoped_guard(mutex, &chip->lock) {
 213                 chip->lines[offset].dir = GPIO_LINE_DIRECTION_OUT;
 214                 __gpio_mockup_set(chip, offset, value);
 215         }
 216
 217         return 0;
 218 }
 219
 220 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
 221 {
 222         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 223
 224         scoped_guard(mutex, &chip->lock)
 225                 chip->lines[offset].dir = GPIO_LINE_DIRECTION_IN;
 226
 227         return 0;
 228 }
 229
 230 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
 231 {
 232         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 233         int direction;
 234
 235         scoped_guard(mutex, &chip->lock)
 236                 direction = chip->lines[offset].dir;
 237
 238         return direction;
 239 }
 240
 241 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
 242 {
 243         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 244
 245         return irq_create_mapping(chip->irq_sim_domain, offset);
 246 }
 247
 248 static int gpio_mockup_request(struct gpio_chip *gc, unsigned int offset)
 249 {
 250         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 251
 252         scoped_guard(mutex, &chip->lock)
 253                 chip->lines[offset].requested = true;
 254
 255         return 0;
 256 }
 257
 258 static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
 259 {
 260         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 261
 262         guard(mutex)(&chip->lock);
 263
 264         chip->lines[offset].requested = false;
 265         __gpio_mockup_set(chip, offset, chip->lines[offset].pull);
 266 }
 267
 268 static ssize_t gpio_mockup_debugfs_read(struct file *file,
 269                                         char __user *usr_buf,
 270                                         size_t size, loff_t *ppos)
 271 {
 272         struct gpio_mockup_dbgfs_private *priv;
 273         struct gpio_mockup_chip *chip;
 274         struct seq_file *sfile;
 275         struct gpio_chip *gc;
 276         int val, cnt;
 277         char buf[3];
 278
 279         if (*ppos != 0)
 280                 return 0;
 281
 282         sfile = file->private_data;
 283         priv = sfile->private;
 284         chip = priv->chip;
 285         gc = &chip->gc;
 286
 287         val = gpio_mockup_get(gc, priv->offset);
 288         cnt = snprintf(buf, sizeof(buf), "%d\n", val);
 289
 290         return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt);
 291 }
 292
 293 static ssize_t gpio_mockup_debugfs_write(struct file *file,
 294                                          const char __user *usr_buf,
 295                                          size_t size, loff_t *ppos)
 296 {
 297         struct gpio_mockup_dbgfs_private *priv;
 298         int rv, val;
 299         struct seq_file *sfile;
 300
 301         if (*ppos != 0)
 302                 return -EINVAL;
 303
 304         rv = kstrtoint_from_user(usr_buf, size, 0, &val);
 305         if (rv)
 306                 return rv;
 307         if (val != 0 && val != 1)
 308                 return -EINVAL;
 309
 310         sfile = file->private_data;
 311         priv = sfile->private;
 312         rv = gpio_mockup_apply_pull(priv->chip, priv->offset, val);
 313         if (rv)
 314                 return rv;
 315
 316         return size;
 317 }
 318
 319 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
 320 {
 321         return single_open(file, NULL, inode->i_private);
 322 }
 323
 324 /*
 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.
 328  *
 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
 331  * down.
 332  *
 333  * Examples:
 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
 340  *   configuration
 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
 344  */
 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,
 350         .release = single_release,
 351 };
 352
 353 static void gpio_mockup_debugfs_setup(struct device *dev,
 354                                       struct gpio_mockup_chip *chip)
 355 {
 356         struct gpio_mockup_dbgfs_private *priv;
 357         struct gpio_chip *gc;
 358         const char *devname;
 359         char *name;
 360         int i;
 361
 362         gc = &chip->gc;
 363
 364         /*
 365          * There can only be a single GPIO device per platform device in
 366          * gpio-mockup so using device_find_any_child() is OK.
 367          */
 368         struct device *child __free(put_device) = device_find_any_child(dev);
 369         if (!child)
 370                 return;
 371
 372         devname = dev_name(child);
 373         chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
 374
 375         for (i = 0; i < gc->ngpio; i++) {
 376                 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
 377                 if (!name)
 378                         return;
 379
 380                 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 381                 if (!priv)
 382                         return;
 383
 384                 priv->chip = chip;
 385                 priv->offset = i;
 386
 387                 debugfs_create_file(name, 0600, chip->dbg_dir, priv,
 388                                     &gpio_mockup_debugfs_ops);
 389         }
 390 }
 391
 392 static void gpio_mockup_debugfs_cleanup(void *data)
 393 {
 394         struct gpio_mockup_chip *chip = data;
 395
 396         debugfs_remove_recursive(chip->dbg_dir);
 397 }
 398
 399 static void gpio_mockup_dispose_mappings(void *data)
 400 {
 401         struct gpio_mockup_chip *chip = data;
 402         struct gpio_chip *gc = &chip->gc;
 403         int i, irq;
 404
 405         for (i = 0; i < gc->ngpio; i++) {
 406                 irq = irq_find_mapping(chip->irq_sim_domain, i);
 407                 if (irq)
 408                         irq_dispose_mapping(irq);
 409         }
 410 }
 411
 412 static int gpio_mockup_probe(struct platform_device *pdev)
 413 {
 414         struct gpio_mockup_chip *chip;
 415         struct gpio_chip *gc;
 416         struct device *dev;
 417         const char *name;
 418         int rv, base, i;
 419         u16 ngpio;
 420
 421         dev = &pdev->dev;
 422
 423         rv = device_property_read_u32(dev, "gpio-base", &base);
 424         if (rv)
 425                 base = -1;
 426
 427         rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
 428         if (rv)
 429                 return rv;
 430
 431         rv = device_property_read_string(dev, "chip-label", &name);
 432         if (rv)
 433                 name = dev_name(dev);
 434
 435         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 436         if (!chip)
 437                 return -ENOMEM;
 438
 439         mutex_init(&chip->lock);
 440
 441         gc = &chip->gc;
 442         gc->base = base;
 443         gc->ngpio = ngpio;
 444         gc->label = name;
 445         gc->owner = THIS_MODULE;
 446         gc->parent = dev;
 447         gc->get = gpio_mockup_get;
 448         gc->set = gpio_mockup_set;
 449         gc->get_multiple = gpio_mockup_get_multiple;
 450         gc->set_multiple = gpio_mockup_set_multiple;
 451         gc->direction_output = gpio_mockup_dirout;
 452         gc->direction_input = gpio_mockup_dirin;
 453         gc->get_direction = gpio_mockup_get_direction;
 454         gc->set_config = gpio_mockup_set_config;
 455         gc->to_irq = gpio_mockup_to_irq;
 456         gc->request = gpio_mockup_request;
 457         gc->free = gpio_mockup_free;
 458
 459         chip->lines = devm_kcalloc(dev, gc->ngpio,
 460                                    sizeof(*chip->lines), GFP_KERNEL);
 461         if (!chip->lines)
 462                 return -ENOMEM;
 463
 464         for (i = 0; i < gc->ngpio; i++)
 465                 chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
 466
 467         chip->irq_sim_domain = devm_irq_domain_create_sim(dev, NULL,
 468                                                           gc->ngpio);
 469         if (IS_ERR(chip->irq_sim_domain))
 470                 return PTR_ERR(chip->irq_sim_domain);
 471
 472         rv = devm_add_action_or_reset(dev, gpio_mockup_dispose_mappings, chip);
 473         if (rv)
 474                 return rv;
 475
 476         rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
 477         if (rv)
 478                 return rv;
 479
 480         gpio_mockup_debugfs_setup(dev, chip);
 481
 482         return devm_add_action_or_reset(dev, gpio_mockup_debugfs_cleanup, chip);
 483 }
 484
 485 static const struct of_device_id gpio_mockup_of_match[] = {
 486         { .compatible = "gpio-mockup", },
 487         {},
 488 };
 489 MODULE_DEVICE_TABLE(of, gpio_mockup_of_match);
 490
 491 static struct platform_driver gpio_mockup_driver = {
 492         .driver = {
 493                 .name = "gpio-mockup",
 494                 .of_match_table = gpio_mockup_of_match,
 495         },
 496         .probe = gpio_mockup_probe,
 497 };
 498
 499 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
 500
 501 static void gpio_mockup_unregister_pdevs(void)
 502 {
 503         struct platform_device *pdev;
 504         struct fwnode_handle *fwnode;
 505         int i;
 506
 507         for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
 508                 pdev = gpio_mockup_pdevs[i];
 509                 if (!pdev)
 510                         continue;
 511
 512                 fwnode = dev_fwnode(&pdev->dev);
 513                 platform_device_unregister(pdev);
 514                 fwnode_remove_software_node(fwnode);
 515         }
 516 }
 517
 518 static int __init gpio_mockup_register_chip(int idx)
 519 {
 520         struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
 521         struct platform_device_info pdevinfo;
 522         struct platform_device *pdev;
 523         struct fwnode_handle *fwnode;
 524         char **line_names = NULL;
 525         char chip_label[32];
 526         int prop = 0, base;
 527         u16 ngpio;
 528
 529         memset(properties, 0, sizeof(properties));
 530         memset(&pdevinfo, 0, sizeof(pdevinfo));
 531
 532         snprintf(chip_label, sizeof(chip_label), "gpio-mockup-%c", idx + 'A');
 533         properties[prop++] = PROPERTY_ENTRY_STRING("chip-label", chip_label);
 534
 535         base = gpio_mockup_range_base(idx);
 536         if (base >= 0)
 537                 properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", base);
 538
 539         ngpio = base < 0 ? gpio_mockup_range_ngpio(idx)
 540                          : gpio_mockup_range_ngpio(idx) - base;
 541         properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
 542
 543         if (gpio_mockup_named_lines) {
 544                 line_names = kasprintf_strarray(GFP_KERNEL, chip_label, ngpio);
 545                 if (!line_names)
 546                         return -ENOMEM;
 547
 548                 properties[prop++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
 549                                         "gpio-line-names", line_names, ngpio);
 550         }
 551
 552         fwnode = fwnode_create_software_node(properties, NULL);
 553         if (IS_ERR(fwnode)) {
 554                 kfree_strarray(line_names, ngpio);
 555                 return PTR_ERR(fwnode);
 556         }
 557
 558         pdevinfo.name = "gpio-mockup";
 559         pdevinfo.id = idx;
 560         pdevinfo.fwnode = fwnode;
 561
 562         pdev = platform_device_register_full(&pdevinfo);
 563         kfree_strarray(line_names, ngpio);
 564         if (IS_ERR(pdev)) {
 565                 fwnode_remove_software_node(fwnode);
 566                 pr_err("error registering device");
 567                 return PTR_ERR(pdev);
 568         }
 569
 570         gpio_mockup_pdevs[idx] = pdev;
 571
 572         return 0;
 573 }
 574
 575 static int __init gpio_mockup_init(void)
 576 {
 577         int i, num_chips, err;
 578
 579         if ((gpio_mockup_num_ranges % 2) ||
 580             (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
 581                 return -EINVAL;
 582
 583         /* Each chip is described by two values. */
 584         num_chips = gpio_mockup_num_ranges / 2;
 585
 586         /*
 587          * The second value in the <base GPIO - number of GPIOS> pair must
 588          * always be greater than 0.
 589          */
 590         for (i = 0; i < num_chips; i++) {
 591                 if (gpio_mockup_range_ngpio(i) < 0)
 592                         return -EINVAL;
 593         }
 594
 595         gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
 596
 597         err = platform_driver_register(&gpio_mockup_driver);
 598         if (err) {
 599                 pr_err("error registering platform driver\n");
 600                 debugfs_remove_recursive(gpio_mockup_dbg_dir);
 601                 return err;
 602         }
 603
 604         for (i = 0; i < num_chips; i++) {
 605                 err = gpio_mockup_register_chip(i);
 606                 if (err) {
 607                         platform_driver_unregister(&gpio_mockup_driver);
 608                         gpio_mockup_unregister_pdevs();
 609                         debugfs_remove_recursive(gpio_mockup_dbg_dir);
 610                         return err;
 611                 }
 612         }
 613
 614         return 0;
 615 }
 616
 617 static void __exit gpio_mockup_exit(void)
 618 {
 619         gpio_mockup_unregister_pdevs();
 620         debugfs_remove_recursive(gpio_mockup_dbg_dir);
 621         platform_driver_unregister(&gpio_mockup_driver);
 622 }
 623
 624 module_init(gpio_mockup_init);
 625 module_exit(gpio_mockup_exit);
 626
 627 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
 628 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
 629 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
 630 MODULE_DESCRIPTION("GPIO Testing driver");
 631 MODULE_LICENSE("GPL v2");