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 #include <linux/debugfs.h>
  11 #include <linux/gpio/consumer.h>
  12 #include <linux/gpio/driver.h>
  13 #include <linux/init.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/irq.h>
  16 #include <linux/irq_sim.h>
  17 #include <linux/module.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/property.h>
  20 #include <linux/slab.h>
  21 #include <linux/uaccess.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 /*
  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_sim irqsim;
  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         struct gpio_desc *desc;
 148         struct gpio_chip *gc;
 149         struct irq_sim *sim;
 150         int curr, irq, irq_type;
 151
 152         gc = &chip->gc;
 153         desc = &gc->gpiodev->descs[offset];
 154         sim = &chip->irqsim;
 155
 156         mutex_lock(&chip->lock);
 157
 158         if (test_bit(FLAG_REQUESTED, &desc->flags) &&
 159             !test_bit(FLAG_IS_OUT, &desc->flags)) {
 160                 curr = __gpio_mockup_get(chip, offset);
 161                 if (curr == value)
 162                         goto out;
 163
 164                 irq = irq_sim_irqnum(sim, offset);
 165                 irq_type = irq_get_trigger_type(irq);
 166
 167                 if ((value == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
 168                     (value == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING)))
 169                         irq_sim_fire(sim, offset);
 170         }
 171
 172         /* Change the value unless we're actively driving the line. */
 173         if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
 174                 !test_bit(FLAG_IS_OUT, &desc->flags))
 175                 __gpio_mockup_set(chip, offset, value);
 176
 177 out:
 178         chip->lines[offset].pull = value;
 179         mutex_unlock(&chip->lock);
 180         return 0;
 181 }
 182
 183 static int gpio_mockup_set_config(struct gpio_chip *gc,
 184                                   unsigned int offset, unsigned long config)
 185 {
 186         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 187
 188         switch (pinconf_to_config_param(config)) {
 189         case PIN_CONFIG_BIAS_PULL_UP:
 190                 return gpio_mockup_apply_pull(chip, offset, 1);
 191         case PIN_CONFIG_BIAS_PULL_DOWN:
 192                 return gpio_mockup_apply_pull(chip, offset, 0);
 193         default:
 194                 break;
 195         }
 196         return -ENOTSUPP;
 197 }
 198
 199 static int gpio_mockup_dirout(struct gpio_chip *gc,
 200                               unsigned int offset, int value)
 201 {
 202         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 203
 204         mutex_lock(&chip->lock);
 205         chip->lines[offset].dir = GPIO_LINE_DIRECTION_OUT;
 206         __gpio_mockup_set(chip, offset, value);
 207         mutex_unlock(&chip->lock);
 208
 209         return 0;
 210 }
 211
 212 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
 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_IN;
 218         mutex_unlock(&chip->lock);
 219
 220         return 0;
 221 }
 222
 223 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
 224 {
 225         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 226         int direction;
 227
 228         mutex_lock(&chip->lock);
 229         direction = chip->lines[offset].dir;
 230         mutex_unlock(&chip->lock);
 231
 232         return direction;
 233 }
 234
 235 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
 236 {
 237         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 238
 239         return irq_sim_irqnum(&chip->irqsim, offset);
 240 }
 241
 242 static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
 243 {
 244         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 245
 246         __gpio_mockup_set(chip, offset, chip->lines[offset].pull);
 247 }
 248
 249 static ssize_t gpio_mockup_debugfs_read(struct file *file,
 250                                         char __user *usr_buf,
 251                                         size_t size, loff_t *ppos)
 252 {
 253         struct gpio_mockup_dbgfs_private *priv;
 254         struct gpio_mockup_chip *chip;
 255         struct seq_file *sfile;
 256         struct gpio_chip *gc;
 257         int val, cnt;
 258         char buf[3];
 259
 260         if (*ppos != 0)
 261                 return 0;
 262
 263         sfile = file->private_data;
 264         priv = sfile->private;
 265         chip = priv->chip;
 266         gc = &chip->gc;
 267
 268         val = gpio_mockup_get(gc, priv->offset);
 269         cnt = snprintf(buf, sizeof(buf), "%d\n", val);
 270
 271         return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt);
 272 }
 273
 274 static ssize_t gpio_mockup_debugfs_write(struct file *file,
 275                                          const char __user *usr_buf,
 276                                          size_t size, loff_t *ppos)
 277 {
 278         struct gpio_mockup_dbgfs_private *priv;
 279         int rv, val;
 280         struct seq_file *sfile;
 281
 282         if (*ppos != 0)
 283                 return -EINVAL;
 284
 285         rv = kstrtoint_from_user(usr_buf, size, 0, &val);
 286         if (rv)
 287                 return rv;
 288         if (val != 0 && val != 1)
 289                 return -EINVAL;
 290
 291         sfile = file->private_data;
 292         priv = sfile->private;
 293         rv = gpio_mockup_apply_pull(priv->chip, priv->offset, val);
 294         if (rv)
 295                 return rv;
 296
 297         return size;
 298 }
 299
 300 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
 301 {
 302         return single_open(file, NULL, inode->i_private);
 303 }
 304
 305 /*
 306  * Each mockup chip is represented by a directory named after the chip's device
 307  * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
 308  * a file using the line's offset as the name under the chip's directory.
 309  *
 310  * Reading from the line's file yields the current *value*, writing to the
 311  * line's file changes the current *pull*. Default pull for mockup lines is
 312  * down.
 313  *
 314  * Examples:
 315  * - when a line pulled down is requested in output mode and driven high, its
 316  *   value will return to 0 once it's released
 317  * - when the line is requested in output mode and driven high, writing 0 to
 318  *   the corresponding debugfs file will change the pull to down but the
 319  *   reported value will still be 1 until the line is released
 320  * - line requested in input mode always reports the same value as its pull
 321  *   configuration
 322  * - when the line is requested in input mode and monitored for events, writing
 323  *   the same value to the debugfs file will be a noop, while writing the
 324  *   opposite value will generate a dummy interrupt with an appropriate edge
 325  */
 326 static const struct file_operations gpio_mockup_debugfs_ops = {
 327         .owner = THIS_MODULE,
 328         .open = gpio_mockup_debugfs_open,
 329         .read = gpio_mockup_debugfs_read,
 330         .write = gpio_mockup_debugfs_write,
 331         .llseek = no_llseek,
 332         .release = single_release,
 333 };
 334
 335 static void gpio_mockup_debugfs_setup(struct device *dev,
 336                                       struct gpio_mockup_chip *chip)
 337 {
 338         struct gpio_mockup_dbgfs_private *priv;
 339         struct gpio_chip *gc;
 340         const char *devname;
 341         char *name;
 342         int i;
 343
 344         gc = &chip->gc;
 345         devname = dev_name(&gc->gpiodev->dev);
 346
 347         chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
 348
 349         for (i = 0; i < gc->ngpio; i++) {
 350                 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
 351                 if (!name)
 352                         return;
 353
 354                 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 355                 if (!priv)
 356                         return;
 357
 358                 priv->chip = chip;
 359                 priv->offset = i;
 360                 priv->desc = &gc->gpiodev->descs[i];
 361
 362                 debugfs_create_file(name, 0200, chip->dbg_dir, priv,
 363                                     &gpio_mockup_debugfs_ops);
 364         }
 365
 366         return;
 367 }
 368
 369 static int gpio_mockup_name_lines(struct device *dev,
 370                                   struct gpio_mockup_chip *chip)
 371 {
 372         struct gpio_chip *gc = &chip->gc;
 373         char **names;
 374         int i;
 375
 376         names = devm_kcalloc(dev, gc->ngpio, sizeof(char *), GFP_KERNEL);
 377         if (!names)
 378                 return -ENOMEM;
 379
 380         for (i = 0; i < gc->ngpio; i++) {
 381                 names[i] = devm_kasprintf(dev, GFP_KERNEL,
 382                                           "%s-%d", gc->label, i);
 383                 if (!names[i])
 384                         return -ENOMEM;
 385         }
 386
 387         gc->names = (const char *const *)names;
 388
 389         return 0;
 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-name", &name);
 412         if (rv)
 413                 name = NULL;
 414
 415         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 416         if (!chip)
 417                 return -ENOMEM;
 418
 419         if (!name) {
 420                 name = devm_kasprintf(dev, GFP_KERNEL,
 421                                       "%s-%c", pdev->name, pdev->id + 'A');
 422                 if (!name)
 423                         return -ENOMEM;
 424         }
 425
 426         mutex_init(&chip->lock);
 427
 428         gc = &chip->gc;
 429         gc->base = base;
 430         gc->ngpio = ngpio;
 431         gc->label = name;
 432         gc->owner = THIS_MODULE;
 433         gc->parent = dev;
 434         gc->get = gpio_mockup_get;
 435         gc->set = gpio_mockup_set;
 436         gc->get_multiple = gpio_mockup_get_multiple;
 437         gc->set_multiple = gpio_mockup_set_multiple;
 438         gc->direction_output = gpio_mockup_dirout;
 439         gc->direction_input = gpio_mockup_dirin;
 440         gc->get_direction = gpio_mockup_get_direction;
 441         gc->set_config = gpio_mockup_set_config;
 442         gc->to_irq = gpio_mockup_to_irq;
 443         gc->free = gpio_mockup_free;
 444
 445         chip->lines = devm_kcalloc(dev, gc->ngpio,
 446                                    sizeof(*chip->lines), GFP_KERNEL);
 447         if (!chip->lines)
 448                 return -ENOMEM;
 449
 450         for (i = 0; i < gc->ngpio; i++)
 451                 chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
 452
 453         if (device_property_read_bool(dev, "named-gpio-lines")) {
 454                 rv = gpio_mockup_name_lines(dev, chip);
 455                 if (rv)
 456                         return rv;
 457         }
 458
 459         rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio);
 460         if (rv < 0)
 461                 return rv;
 462
 463         rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
 464         if (rv)
 465                 return rv;
 466
 467         gpio_mockup_debugfs_setup(dev, chip);
 468
 469         return 0;
 470 }
 471
 472 static struct platform_driver gpio_mockup_driver = {
 473         .driver = {
 474                 .name = GPIO_MOCKUP_NAME,
 475         },
 476         .probe = gpio_mockup_probe,
 477 };
 478
 479 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
 480
 481 static void gpio_mockup_unregister_pdevs(void)
 482 {
 483         struct platform_device *pdev;
 484         int i;
 485
 486         for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
 487                 pdev = gpio_mockup_pdevs[i];
 488
 489                 if (pdev)
 490                         platform_device_unregister(pdev);
 491         }
 492 }
 493
 494 static int __init gpio_mockup_init(void)
 495 {
 496         struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
 497         int i, prop, num_chips, err = 0, base;
 498         struct platform_device_info pdevinfo;
 499         struct platform_device *pdev;
 500         u16 ngpio;
 501
 502         if ((gpio_mockup_num_ranges < 2) ||
 503             (gpio_mockup_num_ranges % 2) ||
 504             (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
 505                 return -EINVAL;
 506
 507         /* Each chip is described by two values. */
 508         num_chips = gpio_mockup_num_ranges / 2;
 509
 510         /*
 511          * The second value in the <base GPIO - number of GPIOS> pair must
 512          * always be greater than 0.
 513          */
 514         for (i = 0; i < num_chips; i++) {
 515                 if (gpio_mockup_range_ngpio(i) < 0)
 516                         return -EINVAL;
 517         }
 518
 519         gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
 520
 521         err = platform_driver_register(&gpio_mockup_driver);
 522         if (err) {
 523                 gpio_mockup_err("error registering platform driver\n");
 524                 return err;
 525         }
 526
 527         for (i = 0; i < num_chips; i++) {
 528                 memset(properties, 0, sizeof(properties));
 529                 memset(&pdevinfo, 0, sizeof(pdevinfo));
 530                 prop = 0;
 531
 532                 base = gpio_mockup_range_base(i);
 533                 if (base >= 0)
 534                         properties[prop++] = PROPERTY_ENTRY_U32("gpio-base",
 535                                                                 base);
 536
 537                 ngpio = base < 0 ? gpio_mockup_range_ngpio(i)
 538                                  : gpio_mockup_range_ngpio(i) - base;
 539                 properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
 540
 541                 if (gpio_mockup_named_lines)
 542                         properties[prop++] = PROPERTY_ENTRY_BOOL(
 543                                                 "named-gpio-lines");
 544
 545                 pdevinfo.name = GPIO_MOCKUP_NAME;
 546                 pdevinfo.id = i;
 547                 pdevinfo.properties = properties;
 548
 549                 pdev = platform_device_register_full(&pdevinfo);
 550                 if (IS_ERR(pdev)) {
 551                         gpio_mockup_err("error registering device");
 552                         platform_driver_unregister(&gpio_mockup_driver);
 553                         gpio_mockup_unregister_pdevs();
 554                         return PTR_ERR(pdev);
 555                 }
 556
 557                 gpio_mockup_pdevs[i] = pdev;
 558         }
 559
 560         return 0;
 561 }
 562
 563 static void __exit gpio_mockup_exit(void)
 564 {
 565         debugfs_remove_recursive(gpio_mockup_dbg_dir);
 566         platform_driver_unregister(&gpio_mockup_driver);
 567         gpio_mockup_unregister_pdevs();
 568 }
 569
 570 module_init(gpio_mockup_init);
 571 module_exit(gpio_mockup_exit);
 572
 573 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
 574 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
 575 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
 576 MODULE_DESCRIPTION("GPIO Testing driver");
 577 MODULE_LICENSE("GPL v2");