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 int i, n = 0; 69 int error = 0; 70 71 unsigned long *bitmap __free(bitmap) = 72 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 return error; 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 return error; 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 return error; 102 } 103 104 args = next_arg(args, &name, &p); 105 } 106 107 if (!n) { 108 pr_err("No GPIOs specified\n"); 109 return -EINVAL; 110 } 111 112 return 0; 113 } 114 115 static ssize_t new_device_store(struct device_driver *driver, const char *buf, 116 size_t count) 117 { 118 struct gpio_aggregator *aggr; 119 struct platform_device *pdev; 120 int res, id; 121 122 if (!try_module_get(THIS_MODULE)) 123 return -ENOENT; 124 125 /* kernfs guarantees string termination, so count + 1 is safe */ 126 aggr = kzalloc(sizeof(*aggr) + count + 1, GFP_KERNEL); 127 if (!aggr) { 128 res = -ENOMEM; 129 goto put_module; 130 } 131 132 memcpy(aggr->args, buf, count + 1); 133 134 aggr->lookups = kzalloc(struct_size(aggr->lookups, table, 1), 135 GFP_KERNEL); 136 if (!aggr->lookups) { 137 res = -ENOMEM; 138 goto free_ga; 139 } 140 141 mutex_lock(&gpio_aggregator_lock); 142 id = idr_alloc(&gpio_aggregator_idr, aggr, 0, 0, GFP_KERNEL); 143 mutex_unlock(&gpio_aggregator_lock); 144 145 if (id < 0) { 146 res = id; 147 goto free_table; 148 } 149 150 aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, id); 151 if (!aggr->lookups->dev_id) { 152 res = -ENOMEM; 153 goto remove_idr; 154 } 155 156 res = aggr_parse(aggr); 157 if (res) 158 goto free_dev_id; 159 160 gpiod_add_lookup_table(aggr->lookups); 161 162 pdev = platform_device_register_simple(DRV_NAME, id, NULL, 0); 163 if (IS_ERR(pdev)) { 164 res = PTR_ERR(pdev); 165 goto remove_table; 166 } 167 168 aggr->pdev = pdev; 169 module_put(THIS_MODULE); 170 return count; 171 172 remove_table: 173 gpiod_remove_lookup_table(aggr->lookups); 174 free_dev_id: 175 kfree(aggr->lookups->dev_id); 176 remove_idr: 177 mutex_lock(&gpio_aggregator_lock); 178 idr_remove(&gpio_aggregator_idr, id); 179 mutex_unlock(&gpio_aggregator_lock); 180 free_table: 181 kfree(aggr->lookups); 182 free_ga: 183 kfree(aggr); 184 put_module: 185 module_put(THIS_MODULE); 186 return res; 187 } 188 189 static DRIVER_ATTR_WO(new_device); 190 191 static void gpio_aggregator_free(struct gpio_aggregator *aggr) 192 { 193 platform_device_unregister(aggr->pdev); 194 gpiod_remove_lookup_table(aggr->lookups); 195 kfree(aggr->lookups->dev_id); 196 kfree(aggr->lookups); 197 kfree(aggr); 198 } 199 200 static ssize_t delete_device_store(struct device_driver *driver, 201 const char *buf, size_t count) 202 { 203 struct gpio_aggregator *aggr; 204 unsigned int id; 205 int error; 206 207 if (!str_has_prefix(buf, DRV_NAME ".")) 208 return -EINVAL; 209 210 error = kstrtouint(buf + strlen(DRV_NAME "."), 10, &id); 211 if (error) 212 return error; 213 214 if (!try_module_get(THIS_MODULE)) 215 return -ENOENT; 216 217 mutex_lock(&gpio_aggregator_lock); 218 aggr = idr_remove(&gpio_aggregator_idr, id); 219 mutex_unlock(&gpio_aggregator_lock); 220 if (!aggr) { 221 module_put(THIS_MODULE); 222 return -ENOENT; 223 } 224 225 gpio_aggregator_free(aggr); 226 module_put(THIS_MODULE); 227 return count; 228 } 229 static DRIVER_ATTR_WO(delete_device); 230 231 static struct attribute *gpio_aggregator_attrs[] = { 232 &driver_attr_new_device.attr, 233 &driver_attr_delete_device.attr, 234 NULL 235 }; 236 ATTRIBUTE_GROUPS(gpio_aggregator); 237 238 static int __exit gpio_aggregator_idr_remove(int id, void *p, void *data) 239 { 240 gpio_aggregator_free(p); 241 return 0; 242 } 243 244 static void __exit gpio_aggregator_remove_all(void) 245 { 246 mutex_lock(&gpio_aggregator_lock); 247 idr_for_each(&gpio_aggregator_idr, gpio_aggregator_idr_remove, NULL); 248 idr_destroy(&gpio_aggregator_idr); 249 mutex_unlock(&gpio_aggregator_lock); 250 } 251 252 253 /* 254 * GPIO Forwarder 255 */ 256 257 struct gpiochip_fwd_timing { 258 u32 ramp_up_us; 259 u32 ramp_down_us; 260 }; 261 262 struct gpiochip_fwd { 263 struct gpio_chip chip; 264 struct gpio_desc **descs; 265 union { 266 struct mutex mlock; /* protects tmp[] if can_sleep */ 267 spinlock_t slock; /* protects tmp[] if !can_sleep */ 268 }; 269 struct gpiochip_fwd_timing *delay_timings; 270 unsigned long tmp[]; /* values and descs for multiple ops */ 271 }; 272 273 #define fwd_tmp_values(fwd) &(fwd)->tmp[0] 274 #define fwd_tmp_descs(fwd) (void *)&(fwd)->tmp[BITS_TO_LONGS((fwd)->chip.ngpio)] 275 276 #define fwd_tmp_size(ngpios) (BITS_TO_LONGS((ngpios)) + (ngpios)) 277 278 static int gpio_fwd_get_direction(struct gpio_chip *chip, unsigned int offset) 279 { 280 struct gpiochip_fwd *fwd = gpiochip_get_data(chip); 281 282 return gpiod_get_direction(fwd->descs[offset]); 283 } 284 285 static int gpio_fwd_direction_input(struct gpio_chip *chip, unsigned int offset) 286 { 287 struct gpiochip_fwd *fwd = gpiochip_get_data(chip); 288 289 return gpiod_direction_input(fwd->descs[offset]); 290 } 291 292 static int gpio_fwd_direction_output(struct gpio_chip *chip, 293 unsigned int offset, int value) 294 { 295 struct gpiochip_fwd *fwd = gpiochip_get_data(chip); 296 297 return gpiod_direction_output(fwd->descs[offset], value); 298 } 299 300 static int gpio_fwd_get(struct gpio_chip *chip, unsigned int offset) 301 { 302 struct gpiochip_fwd *fwd = gpiochip_get_data(chip); 303 304 return chip->can_sleep ? gpiod_get_value_cansleep(fwd->descs[offset]) 305 : gpiod_get_value(fwd->descs[offset]); 306 } 307 308 static int gpio_fwd_get_multiple(struct gpiochip_fwd *fwd, unsigned long *mask, 309 unsigned long *bits) 310 { 311 struct gpio_desc **descs = fwd_tmp_descs(fwd); 312 unsigned long *values = fwd_tmp_values(fwd); 313 unsigned int i, j = 0; 314 int error; 315 316 bitmap_clear(values, 0, fwd->chip.ngpio); 317 for_each_set_bit(i, mask, fwd->chip.ngpio) 318 descs[j++] = fwd->descs[i]; 319 320 if (fwd->chip.can_sleep) 321 error = gpiod_get_array_value_cansleep(j, descs, NULL, values); 322 else 323 error = gpiod_get_array_value(j, descs, NULL, values); 324 if (error) 325 return error; 326 327 j = 0; 328 for_each_set_bit(i, mask, fwd->chip.ngpio) 329 __assign_bit(i, bits, test_bit(j++, values)); 330 331 return 0; 332 } 333 334 static int gpio_fwd_get_multiple_locked(struct gpio_chip *chip, 335 unsigned long *mask, unsigned long *bits) 336 { 337 struct gpiochip_fwd *fwd = gpiochip_get_data(chip); 338 unsigned long flags; 339 int error; 340 341 if (chip->can_sleep) { 342 mutex_lock(&fwd->mlock); 343 error = gpio_fwd_get_multiple(fwd, mask, bits); 344 mutex_unlock(&fwd->mlock); 345 } else { 346 spin_lock_irqsave(&fwd->slock, flags); 347 error = gpio_fwd_get_multiple(fwd, mask, bits); 348 spin_unlock_irqrestore(&fwd->slock, flags); 349 } 350 351 return error; 352 } 353 354 static void gpio_fwd_delay(struct gpio_chip *chip, unsigned int offset, int value) 355 { 356 struct gpiochip_fwd *fwd = gpiochip_get_data(chip); 357 const struct gpiochip_fwd_timing *delay_timings; 358 bool is_active_low = gpiod_is_active_low(fwd->descs[offset]); 359 u32 delay_us; 360 361 delay_timings = &fwd->delay_timings[offset]; 362 if ((!is_active_low && value) || (is_active_low && !value)) 363 delay_us = delay_timings->ramp_up_us; 364 else 365 delay_us = delay_timings->ramp_down_us; 366 if (!delay_us) 367 return; 368 369 if (chip->can_sleep) 370 fsleep(delay_us); 371 else 372 udelay(delay_us); 373 } 374 375 static void gpio_fwd_set(struct gpio_chip *chip, unsigned int offset, int value) 376 { 377 struct gpiochip_fwd *fwd = gpiochip_get_data(chip); 378 379 if (chip->can_sleep) 380 gpiod_set_value_cansleep(fwd->descs[offset], value); 381 else 382 gpiod_set_value(fwd->descs[offset], value); 383 384 if (fwd->delay_timings) 385 gpio_fwd_delay(chip, offset, value); 386 } 387 388 static void gpio_fwd_set_multiple(struct gpiochip_fwd *fwd, unsigned long *mask, 389 unsigned long *bits) 390 { 391 struct gpio_desc **descs = fwd_tmp_descs(fwd); 392 unsigned long *values = fwd_tmp_values(fwd); 393 unsigned int i, j = 0; 394 395 for_each_set_bit(i, mask, fwd->chip.ngpio) { 396 __assign_bit(j, values, test_bit(i, bits)); 397 descs[j++] = fwd->descs[i]; 398 } 399 400 if (fwd->chip.can_sleep) 401 gpiod_set_array_value_cansleep(j, descs, NULL, values); 402 else 403 gpiod_set_array_value(j, descs, NULL, values); 404 } 405 406 static void gpio_fwd_set_multiple_locked(struct gpio_chip *chip, 407 unsigned long *mask, unsigned long *bits) 408 { 409 struct gpiochip_fwd *fwd = gpiochip_get_data(chip); 410 unsigned long flags; 411 412 if (chip->can_sleep) { 413 mutex_lock(&fwd->mlock); 414 gpio_fwd_set_multiple(fwd, mask, bits); 415 mutex_unlock(&fwd->mlock); 416 } else { 417 spin_lock_irqsave(&fwd->slock, flags); 418 gpio_fwd_set_multiple(fwd, mask, bits); 419 spin_unlock_irqrestore(&fwd->slock, flags); 420 } 421 } 422 423 static int gpio_fwd_set_config(struct gpio_chip *chip, unsigned int offset, 424 unsigned long config) 425 { 426 struct gpiochip_fwd *fwd = gpiochip_get_data(chip); 427 428 return gpiod_set_config(fwd->descs[offset], config); 429 } 430 431 static int gpio_fwd_to_irq(struct gpio_chip *chip, unsigned int offset) 432 { 433 struct gpiochip_fwd *fwd = gpiochip_get_data(chip); 434 435 return gpiod_to_irq(fwd->descs[offset]); 436 } 437 438 /* 439 * The GPIO delay provides a way to configure platform specific delays 440 * for the GPIO ramp-up or ramp-down delays. This can serve the following 441 * purposes: 442 * - Open-drain output using an RC filter 443 */ 444 #define FWD_FEATURE_DELAY BIT(0) 445 446 #ifdef CONFIG_OF_GPIO 447 static int gpiochip_fwd_delay_of_xlate(struct gpio_chip *chip, 448 const struct of_phandle_args *gpiospec, 449 u32 *flags) 450 { 451 struct gpiochip_fwd *fwd = gpiochip_get_data(chip); 452 struct gpiochip_fwd_timing *timings; 453 u32 line; 454 455 if (gpiospec->args_count != chip->of_gpio_n_cells) 456 return -EINVAL; 457 458 line = gpiospec->args[0]; 459 if (line >= chip->ngpio) 460 return -EINVAL; 461 462 timings = &fwd->delay_timings[line]; 463 timings->ramp_up_us = gpiospec->args[1]; 464 timings->ramp_down_us = gpiospec->args[2]; 465 466 return line; 467 } 468 469 static int gpiochip_fwd_setup_delay_line(struct device *dev, struct gpio_chip *chip, 470 struct gpiochip_fwd *fwd) 471 { 472 fwd->delay_timings = devm_kcalloc(dev, chip->ngpio, 473 sizeof(*fwd->delay_timings), 474 GFP_KERNEL); 475 if (!fwd->delay_timings) 476 return -ENOMEM; 477 478 chip->of_xlate = gpiochip_fwd_delay_of_xlate; 479 chip->of_gpio_n_cells = 3; 480 481 return 0; 482 } 483 #else 484 static int gpiochip_fwd_setup_delay_line(struct device *dev, struct gpio_chip *chip, 485 struct gpiochip_fwd *fwd) 486 { 487 return 0; 488 } 489 #endif /* !CONFIG_OF_GPIO */ 490 491 /** 492 * gpiochip_fwd_create() - Create a new GPIO forwarder 493 * @dev: Parent device pointer 494 * @ngpios: Number of GPIOs in the forwarder. 495 * @descs: Array containing the GPIO descriptors to forward to. 496 * This array must contain @ngpios entries, and must not be deallocated 497 * before the forwarder has been destroyed again. 498 * @features: Bitwise ORed features as defined with FWD_FEATURE_*. 499 * 500 * This function creates a new gpiochip, which forwards all GPIO operations to 501 * the passed GPIO descriptors. 502 * 503 * Return: An opaque object pointer, or an ERR_PTR()-encoded negative error 504 * code on failure. 505 */ 506 static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev, 507 unsigned int ngpios, 508 struct gpio_desc *descs[], 509 unsigned long features) 510 { 511 const char *label = dev_name(dev); 512 struct gpiochip_fwd *fwd; 513 struct gpio_chip *chip; 514 unsigned int i; 515 int error; 516 517 fwd = devm_kzalloc(dev, struct_size(fwd, tmp, fwd_tmp_size(ngpios)), 518 GFP_KERNEL); 519 if (!fwd) 520 return ERR_PTR(-ENOMEM); 521 522 chip = &fwd->chip; 523 524 /* 525 * If any of the GPIO lines are sleeping, then the entire forwarder 526 * will be sleeping. 527 * If any of the chips support .set_config(), then the forwarder will 528 * support setting configs. 529 */ 530 for (i = 0; i < ngpios; i++) { 531 struct gpio_chip *parent = gpiod_to_chip(descs[i]); 532 533 dev_dbg(dev, "%u => gpio %d irq %d\n", i, 534 desc_to_gpio(descs[i]), gpiod_to_irq(descs[i])); 535 536 if (gpiod_cansleep(descs[i])) 537 chip->can_sleep = true; 538 if (parent && parent->set_config) 539 chip->set_config = gpio_fwd_set_config; 540 } 541 542 chip->label = label; 543 chip->parent = dev; 544 chip->owner = THIS_MODULE; 545 chip->get_direction = gpio_fwd_get_direction; 546 chip->direction_input = gpio_fwd_direction_input; 547 chip->direction_output = gpio_fwd_direction_output; 548 chip->get = gpio_fwd_get; 549 chip->get_multiple = gpio_fwd_get_multiple_locked; 550 chip->set = gpio_fwd_set; 551 chip->set_multiple = gpio_fwd_set_multiple_locked; 552 chip->to_irq = gpio_fwd_to_irq; 553 chip->base = -1; 554 chip->ngpio = ngpios; 555 fwd->descs = descs; 556 557 if (chip->can_sleep) 558 mutex_init(&fwd->mlock); 559 else 560 spin_lock_init(&fwd->slock); 561 562 if (features & FWD_FEATURE_DELAY) { 563 error = gpiochip_fwd_setup_delay_line(dev, chip, fwd); 564 if (error) 565 return ERR_PTR(error); 566 } 567 568 error = devm_gpiochip_add_data(dev, chip, fwd); 569 if (error) 570 return ERR_PTR(error); 571 572 return fwd; 573 } 574 575 576 /* 577 * GPIO Aggregator platform device 578 */ 579 580 static int gpio_aggregator_probe(struct platform_device *pdev) 581 { 582 struct device *dev = &pdev->dev; 583 struct gpio_desc **descs; 584 struct gpiochip_fwd *fwd; 585 unsigned long features; 586 int i, n; 587 588 n = gpiod_count(dev, NULL); 589 if (n < 0) 590 return n; 591 592 descs = devm_kmalloc_array(dev, n, sizeof(*descs), GFP_KERNEL); 593 if (!descs) 594 return -ENOMEM; 595 596 for (i = 0; i < n; i++) { 597 descs[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS); 598 if (IS_ERR(descs[i])) 599 return PTR_ERR(descs[i]); 600 } 601 602 features = (uintptr_t)device_get_match_data(dev); 603 fwd = gpiochip_fwd_create(dev, n, descs, features); 604 if (IS_ERR(fwd)) 605 return PTR_ERR(fwd); 606 607 platform_set_drvdata(pdev, fwd); 608 return 0; 609 } 610 611 static const struct of_device_id gpio_aggregator_dt_ids[] = { 612 { 613 .compatible = "gpio-delay", 614 .data = (void *)FWD_FEATURE_DELAY, 615 }, 616 /* 617 * Add GPIO-operated devices controlled from userspace below, 618 * or use "driver_override" in sysfs. 619 */ 620 {} 621 }; 622 MODULE_DEVICE_TABLE(of, gpio_aggregator_dt_ids); 623 624 static struct platform_driver gpio_aggregator_driver = { 625 .probe = gpio_aggregator_probe, 626 .driver = { 627 .name = DRV_NAME, 628 .groups = gpio_aggregator_groups, 629 .of_match_table = gpio_aggregator_dt_ids, 630 }, 631 }; 632 633 static int __init gpio_aggregator_init(void) 634 { 635 return platform_driver_register(&gpio_aggregator_driver); 636 } 637 module_init(gpio_aggregator_init); 638 639 static void __exit gpio_aggregator_exit(void) 640 { 641 gpio_aggregator_remove_all(); 642 platform_driver_unregister(&gpio_aggregator_driver); 643 } 644 module_exit(gpio_aggregator_exit); 645 646 MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>"); 647 MODULE_DESCRIPTION("GPIO Aggregator"); 648 MODULE_LICENSE("GPL v2"); 649