drivers/gpio/gpio-mockup.c

   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
  37 enum {
  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  */
  47 struct gpio_mockup_line_status {
  48         int dir;
  49         int value;
  50         int pull;
  51 };
  52
  53 struct 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
  61 struct gpio_mockup_dbgfs_private {
  62         struct gpio_mockup_chip *chip;
  63         struct gpio_desc *desc;
  64         unsigned int offset;
  65 };
  66
  67 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
  68 static int gpio_mockup_num_ranges;
  69 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
  70
  71 static bool gpio_mockup_named_lines;
  72 module_param_named(gpio_mockup_named_lines,
  73                    gpio_mockup_named_lines, bool, 0400);
  74
  75 static struct dentry *gpio_mockup_dbg_dir;
  76
  77 static int gpio_mockup_range_base(unsigned int index)
  78 {
  79         return gpio_mockup_ranges[index * 2];
  80 }
  81
  82 static int gpio_mockup_range_ngpio(unsigned int index)
  83 {
  84         return gpio_mockup_ranges[index * 2 + 1];
  85 }
  86
  87 static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
  88                              unsigned int offset)
  89 {
  90         return chip->lines[offset].value;
  91 }
  92
  93 static 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
 105 static 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
 121 static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
 122                               unsigned int offset, int value)
 123 {
 124         chip->lines[offset].value = !!value;
 125 }
 126
 127 static 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
 137 static 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
 149 static 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
 162 static 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
 173 static 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
 185 static 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
 192 static 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
 199 static 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         char buf[3];
 208         int val, rv;
 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         snprintf(buf, sizeof(buf), "%d\n", val);
 220
 221         rv = copy_to_user(usr_buf, buf, sizeof(buf));
 222         if (rv)
 223                 return rv;
 224
 225         return sizeof(buf) - 1;
 226 }
 227
 228 static ssize_t gpio_mockup_debugfs_write(struct file *file,
 229                                          const char __user *usr_buf,
 230                                          size_t size, loff_t *ppos)
 231 {
 232         struct gpio_mockup_dbgfs_private *priv;
 233         int rv, val, curr, irq, irq_type;
 234         struct gpio_mockup_chip *chip;
 235         struct seq_file *sfile;
 236         struct gpio_desc *desc;
 237         struct gpio_chip *gc;
 238         struct irq_sim *sim;
 239
 240         if (*ppos != 0)
 241                 return -EINVAL;
 242
 243         rv = kstrtoint_from_user(usr_buf, size, 0, &val);
 244         if (rv)
 245                 return rv;
 246         if (val != 0 && val != 1)
 247                 return -EINVAL;
 248
 249         sfile = file->private_data;
 250         priv = sfile->private;
 251         chip = priv->chip;
 252         gc = &chip->gc;
 253         desc = &gc->gpiodev->descs[priv->offset];
 254         sim = &chip->irqsim;
 255
 256         mutex_lock(&chip->lock);
 257
 258         if (test_bit(FLAG_REQUESTED, &desc->flags) &&
 259             !test_bit(FLAG_IS_OUT, &desc->flags)) {
 260                 curr = __gpio_mockup_get(chip, priv->offset);
 261                 if (curr == val)
 262                         goto out;
 263
 264                 irq = irq_sim_irqnum(sim, priv->offset);
 265                 irq_type = irq_get_trigger_type(irq);
 266
 267                 if ((val == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
 268                     (val == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING)))
 269                         irq_sim_fire(sim, priv->offset);
 270         }
 271
 272         /* Change the value unless we're actively driving the line. */
 273         if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
 274             !test_bit(FLAG_IS_OUT, &desc->flags))
 275                 __gpio_mockup_set(chip, priv->offset, val);
 276
 277 out:
 278         chip->lines[priv->offset].pull = val;
 279         mutex_unlock(&chip->lock);
 280
 281         return size;
 282 }
 283
 284 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
 285 {
 286         return single_open(file, NULL, inode->i_private);
 287 }
 288
 289 /*
 290  * Each mockup chip is represented by a directory named after the chip's device
 291  * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
 292  * a file using the line's offset as the name under the chip's directory.
 293  *
 294  * Reading from the line's file yields the current *value*, writing to the
 295  * line's file changes the current *pull*. Default pull for mockup lines is
 296  * down.
 297  *
 298  * Examples:
 299  * - when a line pulled down is requested in output mode and driven high, its
 300  *   value will return to 0 once it's released
 301  * - when the line is requested in output mode and driven high, writing 0 to
 302  *   the corresponding debugfs file will change the pull to down but the
 303  *   reported value will still be 1 until the line is released
 304  * - line requested in input mode always reports the same value as its pull
 305  *   configuration
 306  * - when the line is requested in input mode and monitored for events, writing
 307  *   the same value to the debugfs file will be a noop, while writing the
 308  *   opposite value will generate a dummy interrupt with an appropriate edge
 309  */
 310 static const struct file_operations gpio_mockup_debugfs_ops = {
 311         .owner = THIS_MODULE,
 312         .open = gpio_mockup_debugfs_open,
 313         .read = gpio_mockup_debugfs_read,
 314         .write = gpio_mockup_debugfs_write,
 315         .llseek = no_llseek,
 316 };
 317
 318 static void gpio_mockup_debugfs_setup(struct device *dev,
 319                                       struct gpio_mockup_chip *chip)
 320 {
 321         struct gpio_mockup_dbgfs_private *priv;
 322         struct dentry *evfile;
 323         struct gpio_chip *gc;
 324         const char *devname;
 325         char *name;
 326         int i;
 327
 328         gc = &chip->gc;
 329         devname = dev_name(&gc->gpiodev->dev);
 330
 331         chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
 332         if (IS_ERR_OR_NULL(chip->dbg_dir))
 333                 goto err;
 334
 335         for (i = 0; i < gc->ngpio; i++) {
 336                 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
 337                 if (!name)
 338                         goto err;
 339
 340                 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 341                 if (!priv)
 342                         goto err;
 343
 344                 priv->chip = chip;
 345                 priv->offset = i;
 346                 priv->desc = &gc->gpiodev->descs[i];
 347
 348                 evfile = debugfs_create_file(name, 0200, chip->dbg_dir, priv,
 349                                              &gpio_mockup_debugfs_ops);
 350                 if (IS_ERR_OR_NULL(evfile))
 351                         goto err;
 352         }
 353
 354         return;
 355
 356 err:
 357         dev_err(dev, "error creating debugfs files\n");
 358 }
 359
 360 static int gpio_mockup_name_lines(struct device *dev,
 361                                   struct gpio_mockup_chip *chip)
 362 {
 363         struct gpio_chip *gc = &chip->gc;
 364         char **names;
 365         int i;
 366
 367         names = devm_kcalloc(dev, gc->ngpio, sizeof(char *), GFP_KERNEL);
 368         if (!names)
 369                 return -ENOMEM;
 370
 371         for (i = 0; i < gc->ngpio; i++) {
 372                 names[i] = devm_kasprintf(dev, GFP_KERNEL,
 373                                           "%s-%d", gc->label, i);
 374                 if (!names[i])
 375                         return -ENOMEM;
 376         }
 377
 378         gc->names = (const char *const *)names;
 379
 380         return 0;
 381 }
 382
 383 static int gpio_mockup_probe(struct platform_device *pdev)
 384 {
 385         struct gpio_mockup_chip *chip;
 386         struct gpio_chip *gc;
 387         struct device *dev;
 388         const char *name;
 389         int rv, base;
 390         u16 ngpio;
 391
 392         dev = &pdev->dev;
 393
 394         rv = device_property_read_u32(dev, "gpio-base", &base);
 395         if (rv)
 396                 base = -1;
 397
 398         rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
 399         if (rv)
 400                 return rv;
 401
 402         rv = device_property_read_string(dev, "chip-name", &name);
 403         if (rv)
 404                 name = NULL;
 405
 406         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 407         if (!chip)
 408                 return -ENOMEM;
 409
 410         if (!name) {
 411                 name = devm_kasprintf(dev, GFP_KERNEL,
 412                                       "%s-%c", pdev->name, pdev->id + 'A');
 413                 if (!name)
 414                         return -ENOMEM;
 415         }
 416
 417         mutex_init(&chip->lock);
 418
 419         gc = &chip->gc;
 420         gc->base = base;
 421         gc->ngpio = ngpio;
 422         gc->label = name;
 423         gc->owner = THIS_MODULE;
 424         gc->parent = dev;
 425         gc->get = gpio_mockup_get;
 426         gc->set = gpio_mockup_set;
 427         gc->get_multiple = gpio_mockup_get_multiple;
 428         gc->set_multiple = gpio_mockup_set_multiple;
 429         gc->direction_output = gpio_mockup_dirout;
 430         gc->direction_input = gpio_mockup_dirin;
 431         gc->get_direction = gpio_mockup_get_direction;
 432         gc->to_irq = gpio_mockup_to_irq;
 433         gc->free = gpio_mockup_free;
 434
 435         chip->lines = devm_kcalloc(dev, gc->ngpio,
 436                                    sizeof(*chip->lines), GFP_KERNEL);
 437         if (!chip->lines)
 438                 return -ENOMEM;
 439
 440         if (device_property_read_bool(dev, "named-gpio-lines")) {
 441                 rv = gpio_mockup_name_lines(dev, chip);
 442                 if (rv)
 443                         return rv;
 444         }
 445
 446         rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio);
 447         if (rv < 0)
 448                 return rv;
 449
 450         rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
 451         if (rv)
 452                 return rv;
 453
 454         if (!IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
 455                 gpio_mockup_debugfs_setup(dev, chip);
 456
 457         return 0;
 458 }
 459
 460 static struct platform_driver gpio_mockup_driver = {
 461         .driver = {
 462                 .name = GPIO_MOCKUP_NAME,
 463         },
 464         .probe = gpio_mockup_probe,
 465 };
 466
 467 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
 468
 469 static void gpio_mockup_unregister_pdevs(void)
 470 {
 471         struct platform_device *pdev;
 472         int i;
 473
 474         for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
 475                 pdev = gpio_mockup_pdevs[i];
 476
 477                 if (pdev)
 478                         platform_device_unregister(pdev);
 479         }
 480 }
 481
 482 static int __init gpio_mockup_init(void)
 483 {
 484         struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
 485         int i, prop, num_chips, err = 0, base;
 486         struct platform_device_info pdevinfo;
 487         struct platform_device *pdev;
 488         u16 ngpio;
 489
 490         if ((gpio_mockup_num_ranges < 2) ||
 491             (gpio_mockup_num_ranges % 2) ||
 492             (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
 493                 return -EINVAL;
 494
 495         /* Each chip is described by two values. */
 496         num_chips = gpio_mockup_num_ranges / 2;
 497
 498         /*
 499          * The second value in the <base GPIO - number of GPIOS> pair must
 500          * always be greater than 0.
 501          */
 502         for (i = 0; i < num_chips; i++) {
 503                 if (gpio_mockup_range_ngpio(i) < 0)
 504                         return -EINVAL;
 505         }
 506
 507         gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
 508         if (IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
 509                 gpio_mockup_err("error creating debugfs directory\n");
 510
 511         err = platform_driver_register(&gpio_mockup_driver);
 512         if (err) {
 513                 gpio_mockup_err("error registering platform driver\n");
 514                 return err;
 515         }
 516
 517         for (i = 0; i < num_chips; i++) {
 518                 memset(properties, 0, sizeof(properties));
 519                 memset(&pdevinfo, 0, sizeof(pdevinfo));
 520                 prop = 0;
 521
 522                 base = gpio_mockup_range_base(i);
 523                 if (base >= 0)
 524                         properties[prop++] = PROPERTY_ENTRY_U32("gpio-base",
 525                                                                 base);
 526
 527                 ngpio = base < 0 ? gpio_mockup_range_ngpio(i)
 528                                  : gpio_mockup_range_ngpio(i) - base;
 529                 properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
 530
 531                 if (gpio_mockup_named_lines)
 532                         properties[prop++] = PROPERTY_ENTRY_BOOL(
 533                                                 "named-gpio-lines");
 534
 535                 pdevinfo.name = GPIO_MOCKUP_NAME;
 536                 pdevinfo.id = i;
 537                 pdevinfo.properties = properties;
 538
 539                 pdev = platform_device_register_full(&pdevinfo);
 540                 if (IS_ERR(pdev)) {
 541                         gpio_mockup_err("error registering device");
 542                         platform_driver_unregister(&gpio_mockup_driver);
 543                         gpio_mockup_unregister_pdevs();
 544                         return PTR_ERR(pdev);
 545                 }
 546
 547                 gpio_mockup_pdevs[i] = pdev;
 548         }
 549
 550         return 0;
 551 }
 552
 553 static void __exit gpio_mockup_exit(void)
 554 {
 555         debugfs_remove_recursive(gpio_mockup_dbg_dir);
 556         platform_driver_unregister(&gpio_mockup_driver);
 557         gpio_mockup_unregister_pdevs();
 558 }
 559
 560 module_init(gpio_mockup_init);
 561 module_exit(gpio_mockup_exit);
 562
 563 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
 564 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
 565 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
 566 MODULE_DESCRIPTION("GPIO Testing driver");
 567 MODULE_LICENSE("GPL v2");