drivers/gpio/gpio-aggregator.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 //
   3 // GPIO Aggregator
   4 //
   5 // Copyright (C) 2019-2020 Glider bv
   6
   7 #define DRV_NAME       "gpio-aggregator"
   8 #define pr_fmt(fmt)     DRV_NAME ": " fmt
   9
  10 #include <linux/bitmap.h>
  11 #include <linux/bitops.h>
  12 #include <linux/ctype.h>
  13 #include <linux/delay.h>
  14 #include <linux/idr.h>
  15 #include <linux/kernel.h>
  16 #include <linux/mod_devicetable.h>
  17 #include <linux/module.h>
  18 #include <linux/mutex.h>
  19 #include <linux/overflow.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/property.h>
  22 #include <linux/slab.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/string.h>
  25
  26 #include <linux/gpio/consumer.h>
  27 #include <linux/gpio/driver.h>
  28 #include <linux/gpio/machine.h>
  29
  30 #define AGGREGATOR_MAX_GPIOS 512
  31
  32 /*
  33  * GPIO Aggregator sysfs interface
  34  */
  35
  36 struct gpio_aggregator {
  37         struct gpiod_lookup_table *lookups;
  38         struct platform_device *pdev;
  39         char args[];
  40 };
  41
  42 static DEFINE_MUTEX(gpio_aggregator_lock);      /* protects idr */
  43 static DEFINE_IDR(gpio_aggregator_idr);
  44
  45 static int aggr_add_gpio(struct gpio_aggregator *aggr, const char *key,
  46                          int hwnum, unsigned int *n)
  47 {
  48         struct gpiod_lookup_table *lookups;
  49
  50         lookups = krealloc(aggr->lookups, struct_size(lookups, table, *n + 2),
  51                            GFP_KERNEL);
  52         if (!lookups)
  53                 return -ENOMEM;
  54
  55         lookups->table[*n] = GPIO_LOOKUP_IDX(key, hwnum, NULL, *n, 0);
  56
  57         (*n)++;
  58         memset(&lookups->table[*n], 0, sizeof(lookups->table[*n]));
  59
  60         aggr->lookups = lookups;
  61         return 0;
  62 }
  63
  64 static int aggr_parse(struct gpio_aggregator *aggr)
  65 {
  66         char *args = skip_spaces(aggr->args);
  67         char *name, *offsets, *p;
  68         unsigned long *bitmap;
  69         unsigned int i, n = 0;
  70         int error = 0;
  71
  72         bitmap = bitmap_alloc(AGGREGATOR_MAX_GPIOS, GFP_KERNEL);
  73         if (!bitmap)
  74                 return -ENOMEM;
  75
  76         args = next_arg(args, &name, &p);
  77         while (*args) {
  78                 args = next_arg(args, &offsets, &p);
  79
  80                 p = get_options(offsets, 0, &error);
  81                 if (error == 0 || *p) {
  82                         /* Named GPIO line */
  83                         error = aggr_add_gpio(aggr, name, U16_MAX, &n);
  84                         if (error)
  85                                 goto free_bitmap;
  86
  87                         name = offsets;
  88                         continue;
  89                 }
  90
  91                 /* GPIO chip + offset(s) */
  92                 error = bitmap_parselist(offsets, bitmap, AGGREGATOR_MAX_GPIOS);
  93                 if (error) {
  94                         pr_err("Cannot parse %s: %d\n", offsets, error);
  95                         goto free_bitmap;
  96                 }
  97
  98                 for_each_set_bit(i, bitmap, AGGREGATOR_MAX_GPIOS) {
  99                         error = aggr_add_gpio(aggr, name, i, &n);
 100                         if (error)
 101                                 goto free_bitmap;
 102                 }
 103
 104                 args = next_arg(args, &name, &p);
 105         }
 106
 107         if (!n) {
 108                 pr_err("No GPIOs specified\n");
 109                 error = -EINVAL;
 110         }
 111
 112 free_bitmap:
 113         bitmap_free(bitmap);
 114         return error;
 115 }
 116
 117 static ssize_t new_device_store(struct device_driver *driver, const char *buf,
 118                                 size_t count)
 119 {
 120         struct gpio_aggregator *aggr;
 121         struct platform_device *pdev;
 122         int res, id;
 123
 124         /* kernfs guarantees string termination, so count + 1 is safe */
 125         aggr = kzalloc(sizeof(*aggr) + count + 1, GFP_KERNEL);
 126         if (!aggr)
 127                 return -ENOMEM;
 128
 129         memcpy(aggr->args, buf, count + 1);
 130
 131         aggr->lookups = kzalloc(struct_size(aggr->lookups, table, 1),
 132                                 GFP_KERNEL);
 133         if (!aggr->lookups) {
 134                 res = -ENOMEM;
 135                 goto free_ga;
 136         }
 137
 138         mutex_lock(&gpio_aggregator_lock);
 139         id = idr_alloc(&gpio_aggregator_idr, aggr, 0, 0, GFP_KERNEL);
 140         mutex_unlock(&gpio_aggregator_lock);
 141
 142         if (id < 0) {
 143                 res = id;
 144                 goto free_table;
 145         }
 146
 147         aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, id);
 148         if (!aggr->lookups->dev_id) {
 149                 res = -ENOMEM;
 150                 goto remove_idr;
 151         }
 152
 153         res = aggr_parse(aggr);
 154         if (res)
 155                 goto free_dev_id;
 156
 157         gpiod_add_lookup_table(aggr->lookups);
 158
 159         pdev = platform_device_register_simple(DRV_NAME, id, NULL, 0);
 160         if (IS_ERR(pdev)) {
 161                 res = PTR_ERR(pdev);
 162                 goto remove_table;
 163         }
 164
 165         aggr->pdev = pdev;
 166         return count;
 167
 168 remove_table:
 169         gpiod_remove_lookup_table(aggr->lookups);
 170 free_dev_id:
 171         kfree(aggr->lookups->dev_id);
 172 remove_idr:
 173         mutex_lock(&gpio_aggregator_lock);
 174         idr_remove(&gpio_aggregator_idr, id);
 175         mutex_unlock(&gpio_aggregator_lock);
 176 free_table:
 177         kfree(aggr->lookups);
 178 free_ga:
 179         kfree(aggr);
 180         return res;
 181 }
 182
 183 static DRIVER_ATTR_WO(new_device);
 184
 185 static void gpio_aggregator_free(struct gpio_aggregator *aggr)
 186 {
 187         platform_device_unregister(aggr->pdev);
 188         gpiod_remove_lookup_table(aggr->lookups);
 189         kfree(aggr->lookups->dev_id);
 190         kfree(aggr->lookups);
 191         kfree(aggr);
 192 }
 193
 194 static ssize_t delete_device_store(struct device_driver *driver,
 195                                    const char *buf, size_t count)
 196 {
 197         struct gpio_aggregator *aggr;
 198         unsigned int id;
 199         int error;
 200
 201         if (!str_has_prefix(buf, DRV_NAME "."))
 202                 return -EINVAL;
 203
 204         error = kstrtouint(buf + strlen(DRV_NAME "."), 10, &id);
 205         if (error)
 206                 return error;
 207
 208         mutex_lock(&gpio_aggregator_lock);
 209         aggr = idr_remove(&gpio_aggregator_idr, id);
 210         mutex_unlock(&gpio_aggregator_lock);
 211         if (!aggr)
 212                 return -ENOENT;
 213
 214         gpio_aggregator_free(aggr);
 215         return count;
 216 }
 217 static DRIVER_ATTR_WO(delete_device);
 218
 219 static struct attribute *gpio_aggregator_attrs[] = {
 220         &driver_attr_new_device.attr,
 221         &driver_attr_delete_device.attr,
 222         NULL
 223 };
 224 ATTRIBUTE_GROUPS(gpio_aggregator);
 225
 226 static int __exit gpio_aggregator_idr_remove(int id, void *p, void *data)
 227 {
 228         gpio_aggregator_free(p);
 229         return 0;
 230 }
 231
 232 static void __exit gpio_aggregator_remove_all(void)
 233 {
 234         mutex_lock(&gpio_aggregator_lock);
 235         idr_for_each(&gpio_aggregator_idr, gpio_aggregator_idr_remove, NULL);
 236         idr_destroy(&gpio_aggregator_idr);
 237         mutex_unlock(&gpio_aggregator_lock);
 238 }
 239
 240
 241 /*
 242  *  GPIO Forwarder
 243  */
 244
 245 struct gpiochip_fwd_timing {
 246         u32 ramp_up_us;
 247         u32 ramp_down_us;
 248 };
 249
 250 struct gpiochip_fwd {
 251         struct gpio_chip chip;
 252         struct gpio_desc **descs;
 253         union {
 254                 struct mutex mlock;     /* protects tmp[] if can_sleep */
 255                 spinlock_t slock;       /* protects tmp[] if !can_sleep */
 256         };
 257         struct gpiochip_fwd_timing *delay_timings;
 258         unsigned long tmp[];            /* values and descs for multiple ops */
 259 };
 260
 261 #define fwd_tmp_values(fwd)     &(fwd)->tmp[0]
 262 #define fwd_tmp_descs(fwd)      (void *)&(fwd)->tmp[BITS_TO_LONGS((fwd)->chip.ngpio)]
 263
 264 #define fwd_tmp_size(ngpios)    (BITS_TO_LONGS((ngpios)) + (ngpios))
 265
 266 static int gpio_fwd_get_direction(struct gpio_chip *chip, unsigned int offset)
 267 {
 268         struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
 269
 270         return gpiod_get_direction(fwd->descs[offset]);
 271 }
 272
 273 static int gpio_fwd_direction_input(struct gpio_chip *chip, unsigned int offset)
 274 {
 275         struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
 276
 277         return gpiod_direction_input(fwd->descs[offset]);
 278 }
 279
 280 static int gpio_fwd_direction_output(struct gpio_chip *chip,
 281                                      unsigned int offset, int value)
 282 {
 283         struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
 284
 285         return gpiod_direction_output(fwd->descs[offset], value);
 286 }
 287
 288 static int gpio_fwd_get(struct gpio_chip *chip, unsigned int offset)
 289 {
 290         struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
 291
 292         return chip->can_sleep ? gpiod_get_value_cansleep(fwd->descs[offset])
 293                                : gpiod_get_value(fwd->descs[offset]);
 294 }
 295
 296 static int gpio_fwd_get_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
 297                                  unsigned long *bits)
 298 {
 299         struct gpio_desc **descs = fwd_tmp_descs(fwd);
 300         unsigned long *values = fwd_tmp_values(fwd);
 301         unsigned int i, j = 0;
 302         int error;
 303
 304         bitmap_clear(values, 0, fwd->chip.ngpio);
 305         for_each_set_bit(i, mask, fwd->chip.ngpio)
 306                 descs[j++] = fwd->descs[i];
 307
 308         if (fwd->chip.can_sleep)
 309                 error = gpiod_get_array_value_cansleep(j, descs, NULL, values);
 310         else
 311                 error = gpiod_get_array_value(j, descs, NULL, values);
 312         if (error)
 313                 return error;
 314
 315         j = 0;
 316         for_each_set_bit(i, mask, fwd->chip.ngpio)
 317                 __assign_bit(i, bits, test_bit(j++, values));
 318
 319         return 0;
 320 }
 321
 322 static int gpio_fwd_get_multiple_locked(struct gpio_chip *chip,
 323                                         unsigned long *mask, unsigned long *bits)
 324 {
 325         struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
 326         unsigned long flags;
 327         int error;
 328
 329         if (chip->can_sleep) {
 330                 mutex_lock(&fwd->mlock);
 331                 error = gpio_fwd_get_multiple(fwd, mask, bits);
 332                 mutex_unlock(&fwd->mlock);
 333         } else {
 334                 spin_lock_irqsave(&fwd->slock, flags);
 335                 error = gpio_fwd_get_multiple(fwd, mask, bits);
 336                 spin_unlock_irqrestore(&fwd->slock, flags);
 337         }
 338
 339         return error;
 340 }
 341
 342 static void gpio_fwd_delay(struct gpio_chip *chip, unsigned int offset, int value)
 343 {
 344         struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
 345         const struct gpiochip_fwd_timing *delay_timings;
 346         bool is_active_low = gpiod_is_active_low(fwd->descs[offset]);
 347         u32 delay_us;
 348
 349         delay_timings = &fwd->delay_timings[offset];
 350         if ((!is_active_low && value) || (is_active_low && !value))
 351                 delay_us = delay_timings->ramp_up_us;
 352         else
 353                 delay_us = delay_timings->ramp_down_us;
 354         if (!delay_us)
 355                 return;
 356
 357         if (chip->can_sleep)
 358                 fsleep(delay_us);
 359         else
 360                 udelay(delay_us);
 361 }
 362
 363 static void gpio_fwd_set(struct gpio_chip *chip, unsigned int offset, int value)
 364 {
 365         struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
 366
 367         if (chip->can_sleep)
 368                 gpiod_set_value_cansleep(fwd->descs[offset], value);
 369         else
 370                 gpiod_set_value(fwd->descs[offset], value);
 371
 372         if (fwd->delay_timings)
 373                 gpio_fwd_delay(chip, offset, value);
 374 }
 375
 376 static void gpio_fwd_set_multiple(struct gpiochip_fwd *fwd, unsigned long *mask,
 377                                   unsigned long *bits)
 378 {
 379         struct gpio_desc **descs = fwd_tmp_descs(fwd);
 380         unsigned long *values = fwd_tmp_values(fwd);
 381         unsigned int i, j = 0;
 382
 383         for_each_set_bit(i, mask, fwd->chip.ngpio) {
 384                 __assign_bit(j, values, test_bit(i, bits));
 385                 descs[j++] = fwd->descs[i];
 386         }
 387
 388         if (fwd->chip.can_sleep)
 389                 gpiod_set_array_value_cansleep(j, descs, NULL, values);
 390         else
 391                 gpiod_set_array_value(j, descs, NULL, values);
 392 }
 393
 394 static void gpio_fwd_set_multiple_locked(struct gpio_chip *chip,
 395                                          unsigned long *mask, unsigned long *bits)
 396 {
 397         struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
 398         unsigned long flags;
 399
 400         if (chip->can_sleep) {
 401                 mutex_lock(&fwd->mlock);
 402                 gpio_fwd_set_multiple(fwd, mask, bits);
 403                 mutex_unlock(&fwd->mlock);
 404         } else {
 405                 spin_lock_irqsave(&fwd->slock, flags);
 406                 gpio_fwd_set_multiple(fwd, mask, bits);
 407                 spin_unlock_irqrestore(&fwd->slock, flags);
 408         }
 409 }
 410
 411 static int gpio_fwd_set_config(struct gpio_chip *chip, unsigned int offset,
 412                                unsigned long config)
 413 {
 414         struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
 415
 416         return gpiod_set_config(fwd->descs[offset], config);
 417 }
 418
 419 static int gpio_fwd_to_irq(struct gpio_chip *chip, unsigned int offset)
 420 {
 421         struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
 422
 423         return gpiod_to_irq(fwd->descs[offset]);
 424 }
 425
 426 /*
 427  * The GPIO delay provides a way to configure platform specific delays
 428  * for the GPIO ramp-up or ramp-down delays. This can serve the following
 429  * purposes:
 430  *   - Open-drain output using an RC filter
 431  */
 432 #define FWD_FEATURE_DELAY               BIT(0)
 433
 434 #ifdef CONFIG_OF_GPIO
 435 static int gpiochip_fwd_delay_of_xlate(struct gpio_chip *chip,
 436                                        const struct of_phandle_args *gpiospec,
 437                                        u32 *flags)
 438 {
 439         struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
 440         struct gpiochip_fwd_timing *timings;
 441         u32 line;
 442
 443         if (gpiospec->args_count != chip->of_gpio_n_cells)
 444                 return -EINVAL;
 445
 446         line = gpiospec->args[0];
 447         if (line >= chip->ngpio)
 448                 return -EINVAL;
 449
 450         timings = &fwd->delay_timings[line];
 451         timings->ramp_up_us = gpiospec->args[1];
 452         timings->ramp_down_us = gpiospec->args[2];
 453
 454         return line;
 455 }
 456
 457 static int gpiochip_fwd_setup_delay_line(struct device *dev, struct gpio_chip *chip,
 458                                          struct gpiochip_fwd *fwd)
 459 {
 460         fwd->delay_timings = devm_kcalloc(dev, chip->ngpio,
 461                                           sizeof(*fwd->delay_timings),
 462                                           GFP_KERNEL);
 463         if (!fwd->delay_timings)
 464                 return -ENOMEM;
 465
 466         chip->of_xlate = gpiochip_fwd_delay_of_xlate;
 467         chip->of_gpio_n_cells = 3;
 468
 469         return 0;
 470 }
 471 #else
 472 static int gpiochip_fwd_setup_delay_line(struct device *dev, struct gpio_chip *chip,
 473                                          struct gpiochip_fwd *fwd)
 474 {
 475         return 0;
 476 }
 477 #endif  /* !CONFIG_OF_GPIO */
 478
 479 /**
 480  * gpiochip_fwd_create() - Create a new GPIO forwarder
 481  * @dev: Parent device pointer
 482  * @ngpios: Number of GPIOs in the forwarder.
 483  * @descs: Array containing the GPIO descriptors to forward to.
 484  *         This array must contain @ngpios entries, and must not be deallocated
 485  *         before the forwarder has been destroyed again.
 486  * @features: Bitwise ORed features as defined with FWD_FEATURE_*.
 487  *
 488  * This function creates a new gpiochip, which forwards all GPIO operations to
 489  * the passed GPIO descriptors.
 490  *
 491  * Return: An opaque object pointer, or an ERR_PTR()-encoded negative error
 492  *         code on failure.
 493  */
 494 static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
 495                                                 unsigned int ngpios,
 496                                                 struct gpio_desc *descs[],
 497                                                 unsigned long features)
 498 {
 499         const char *label = dev_name(dev);
 500         struct gpiochip_fwd *fwd;
 501         struct gpio_chip *chip;
 502         unsigned int i;
 503         int error;
 504
 505         fwd = devm_kzalloc(dev, struct_size(fwd, tmp, fwd_tmp_size(ngpios)),
 506                            GFP_KERNEL);
 507         if (!fwd)
 508                 return ERR_PTR(-ENOMEM);
 509
 510         chip = &fwd->chip;
 511
 512         /*
 513          * If any of the GPIO lines are sleeping, then the entire forwarder
 514          * will be sleeping.
 515          * If any of the chips support .set_config(), then the forwarder will
 516          * support setting configs.
 517          */
 518         for (i = 0; i < ngpios; i++) {
 519                 struct gpio_chip *parent = gpiod_to_chip(descs[i]);
 520
 521                 dev_dbg(dev, "%u => gpio %d irq %d\n", i,
 522                         desc_to_gpio(descs[i]), gpiod_to_irq(descs[i]));
 523
 524                 if (gpiod_cansleep(descs[i]))
 525                         chip->can_sleep = true;
 526                 if (parent && parent->set_config)
 527                         chip->set_config = gpio_fwd_set_config;
 528         }
 529
 530         chip->label = label;
 531         chip->parent = dev;
 532         chip->owner = THIS_MODULE;
 533         chip->get_direction = gpio_fwd_get_direction;
 534         chip->direction_input = gpio_fwd_direction_input;
 535         chip->direction_output = gpio_fwd_direction_output;
 536         chip->get = gpio_fwd_get;
 537         chip->get_multiple = gpio_fwd_get_multiple_locked;
 538         chip->set = gpio_fwd_set;
 539         chip->set_multiple = gpio_fwd_set_multiple_locked;
 540         chip->to_irq = gpio_fwd_to_irq;
 541         chip->base = -1;
 542         chip->ngpio = ngpios;
 543         fwd->descs = descs;
 544
 545         if (chip->can_sleep)
 546                 mutex_init(&fwd->mlock);
 547         else
 548                 spin_lock_init(&fwd->slock);
 549
 550         if (features & FWD_FEATURE_DELAY) {
 551                 error = gpiochip_fwd_setup_delay_line(dev, chip, fwd);
 552                 if (error)
 553                         return ERR_PTR(error);
 554         }
 555
 556         error = devm_gpiochip_add_data(dev, chip, fwd);
 557         if (error)
 558                 return ERR_PTR(error);
 559
 560         return fwd;
 561 }
 562
 563
 564 /*
 565  *  GPIO Aggregator platform device
 566  */
 567
 568 static int gpio_aggregator_probe(struct platform_device *pdev)
 569 {
 570         struct device *dev = &pdev->dev;
 571         struct gpio_desc **descs;
 572         struct gpiochip_fwd *fwd;
 573         unsigned long features;
 574         int i, n;
 575
 576         n = gpiod_count(dev, NULL);
 577         if (n < 0)
 578                 return n;
 579
 580         descs = devm_kmalloc_array(dev, n, sizeof(*descs), GFP_KERNEL);
 581         if (!descs)
 582                 return -ENOMEM;
 583
 584         for (i = 0; i < n; i++) {
 585                 descs[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
 586                 if (IS_ERR(descs[i]))
 587                         return PTR_ERR(descs[i]);
 588         }
 589
 590         features = (uintptr_t)device_get_match_data(dev);
 591         fwd = gpiochip_fwd_create(dev, n, descs, features);
 592         if (IS_ERR(fwd))
 593                 return PTR_ERR(fwd);
 594
 595         platform_set_drvdata(pdev, fwd);
 596         return 0;
 597 }
 598
 599 static const struct of_device_id gpio_aggregator_dt_ids[] = {
 600         {
 601                 .compatible = "gpio-delay",
 602                 .data = (void *)FWD_FEATURE_DELAY,
 603         },
 604         /*
 605          * Add GPIO-operated devices controlled from userspace below,
 606          * or use "driver_override" in sysfs.
 607          */
 608         {}
 609 };
 610 MODULE_DEVICE_TABLE(of, gpio_aggregator_dt_ids);
 611
 612 static struct platform_driver gpio_aggregator_driver = {
 613         .probe = gpio_aggregator_probe,
 614         .driver = {
 615                 .name = DRV_NAME,
 616                 .groups = gpio_aggregator_groups,
 617                 .of_match_table = gpio_aggregator_dt_ids,
 618         },
 619 };
 620
 621 static int __init gpio_aggregator_init(void)
 622 {
 623         return platform_driver_register(&gpio_aggregator_driver);
 624 }
 625 module_init(gpio_aggregator_init);
 626
 627 static void __exit gpio_aggregator_exit(void)
 628 {
 629         gpio_aggregator_remove_all();
 630         platform_driver_unregister(&gpio_aggregator_driver);
 631 }
 632 module_exit(gpio_aggregator_exit);
 633
 634 MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
 635 MODULE_DESCRIPTION("GPIO Aggregator");
 636 MODULE_LICENSE("GPL v2");