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 .llseek = no_llseek, 351 .release = single_release, 352 }; 353 354 static void gpio_mockup_debugfs_setup(struct device *dev, 355 struct gpio_mockup_chip *chip) 356 { 357 struct device *child __free(put_device) = NULL; 358 struct gpio_mockup_dbgfs_private *priv; 359 struct gpio_chip *gc; 360 const char *devname; 361 char *name; 362 int i; 363 364 gc = &chip->gc; 365 366 /* 367 * There can only be a single GPIO device per platform device in 368 * gpio-mockup so using device_find_any_child() is OK. 369 */ 370 child = device_find_any_child(dev); 371 if (!child) 372 return; 373 374 devname = dev_name(child); 375 chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir); 376 377 for (i = 0; i < gc->ngpio; i++) { 378 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i); 379 if (!name) 380 return; 381 382 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 383 if (!priv) 384 return; 385 386 priv->chip = chip; 387 priv->offset = i; 388 389 debugfs_create_file(name, 0600, chip->dbg_dir, priv, 390 &gpio_mockup_debugfs_ops); 391 } 392 } 393 394 static void gpio_mockup_debugfs_cleanup(void *data) 395 { 396 struct gpio_mockup_chip *chip = data; 397 398 debugfs_remove_recursive(chip->dbg_dir); 399 } 400 401 static void gpio_mockup_dispose_mappings(void *data) 402 { 403 struct gpio_mockup_chip *chip = data; 404 struct gpio_chip *gc = &chip->gc; 405 int i, irq; 406 407 for (i = 0; i < gc->ngpio; i++) { 408 irq = irq_find_mapping(chip->irq_sim_domain, i); 409 if (irq) 410 irq_dispose_mapping(irq); 411 } 412 } 413 414 static int gpio_mockup_probe(struct platform_device *pdev) 415 { 416 struct gpio_mockup_chip *chip; 417 struct gpio_chip *gc; 418 struct device *dev; 419 const char *name; 420 int rv, base, i; 421 u16 ngpio; 422 423 dev = &pdev->dev; 424 425 rv = device_property_read_u32(dev, "gpio-base", &base); 426 if (rv) 427 base = -1; 428 429 rv = device_property_read_u16(dev, "nr-gpios", &ngpio); 430 if (rv) 431 return rv; 432 433 rv = device_property_read_string(dev, "chip-label", &name); 434 if (rv) 435 name = dev_name(dev); 436 437 chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL); 438 if (!chip) 439 return -ENOMEM; 440 441 mutex_init(&chip->lock); 442 443 gc = &chip->gc; 444 gc->base = base; 445 gc->ngpio = ngpio; 446 gc->label = name; 447 gc->owner = THIS_MODULE; 448 gc->parent = dev; 449 gc->get = gpio_mockup_get; 450 gc->set = gpio_mockup_set; 451 gc->get_multiple = gpio_mockup_get_multiple; 452 gc->set_multiple = gpio_mockup_set_multiple; 453 gc->direction_output = gpio_mockup_dirout; 454 gc->direction_input = gpio_mockup_dirin; 455 gc->get_direction = gpio_mockup_get_direction; 456 gc->set_config = gpio_mockup_set_config; 457 gc->to_irq = gpio_mockup_to_irq; 458 gc->request = gpio_mockup_request; 459 gc->free = gpio_mockup_free; 460 461 chip->lines = devm_kcalloc(dev, gc->ngpio, 462 sizeof(*chip->lines), GFP_KERNEL); 463 if (!chip->lines) 464 return -ENOMEM; 465 466 for (i = 0; i < gc->ngpio; i++) 467 chip->lines[i].dir = GPIO_LINE_DIRECTION_IN; 468 469 chip->irq_sim_domain = devm_irq_domain_create_sim(dev, NULL, 470 gc->ngpio); 471 if (IS_ERR(chip->irq_sim_domain)) 472 return PTR_ERR(chip->irq_sim_domain); 473 474 rv = devm_add_action_or_reset(dev, gpio_mockup_dispose_mappings, chip); 475 if (rv) 476 return rv; 477 478 rv = devm_gpiochip_add_data(dev, &chip->gc, chip); 479 if (rv) 480 return rv; 481 482 gpio_mockup_debugfs_setup(dev, chip); 483 484 return devm_add_action_or_reset(dev, gpio_mockup_debugfs_cleanup, chip); 485 } 486 487 static const struct of_device_id gpio_mockup_of_match[] = { 488 { .compatible = "gpio-mockup", }, 489 {}, 490 }; 491 MODULE_DEVICE_TABLE(of, gpio_mockup_of_match); 492 493 static struct platform_driver gpio_mockup_driver = { 494 .driver = { 495 .name = "gpio-mockup", 496 .of_match_table = gpio_mockup_of_match, 497 }, 498 .probe = gpio_mockup_probe, 499 }; 500 501 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC]; 502 503 static void gpio_mockup_unregister_pdevs(void) 504 { 505 struct platform_device *pdev; 506 struct fwnode_handle *fwnode; 507 int i; 508 509 for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) { 510 pdev = gpio_mockup_pdevs[i]; 511 if (!pdev) 512 continue; 513 514 fwnode = dev_fwnode(&pdev->dev); 515 platform_device_unregister(pdev); 516 fwnode_remove_software_node(fwnode); 517 } 518 } 519 520 static int __init gpio_mockup_register_chip(int idx) 521 { 522 struct property_entry properties[GPIO_MOCKUP_MAX_PROP]; 523 struct platform_device_info pdevinfo; 524 struct platform_device *pdev; 525 struct fwnode_handle *fwnode; 526 char **line_names = NULL; 527 char chip_label[32]; 528 int prop = 0, base; 529 u16 ngpio; 530 531 memset(properties, 0, sizeof(properties)); 532 memset(&pdevinfo, 0, sizeof(pdevinfo)); 533 534 snprintf(chip_label, sizeof(chip_label), "gpio-mockup-%c", idx + 'A'); 535 properties[prop++] = PROPERTY_ENTRY_STRING("chip-label", chip_label); 536 537 base = gpio_mockup_range_base(idx); 538 if (base >= 0) 539 properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", base); 540 541 ngpio = base < 0 ? gpio_mockup_range_ngpio(idx) 542 : gpio_mockup_range_ngpio(idx) - base; 543 properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio); 544 545 if (gpio_mockup_named_lines) { 546 line_names = kasprintf_strarray(GFP_KERNEL, chip_label, ngpio); 547 if (!line_names) 548 return -ENOMEM; 549 550 properties[prop++] = PROPERTY_ENTRY_STRING_ARRAY_LEN( 551 "gpio-line-names", line_names, ngpio); 552 } 553 554 fwnode = fwnode_create_software_node(properties, NULL); 555 if (IS_ERR(fwnode)) { 556 kfree_strarray(line_names, ngpio); 557 return PTR_ERR(fwnode); 558 } 559 560 pdevinfo.name = "gpio-mockup"; 561 pdevinfo.id = idx; 562 pdevinfo.fwnode = fwnode; 563 564 pdev = platform_device_register_full(&pdevinfo); 565 kfree_strarray(line_names, ngpio); 566 if (IS_ERR(pdev)) { 567 fwnode_remove_software_node(fwnode); 568 pr_err("error registering device"); 569 return PTR_ERR(pdev); 570 } 571 572 gpio_mockup_pdevs[idx] = pdev; 573 574 return 0; 575 } 576 577 static int __init gpio_mockup_init(void) 578 { 579 int i, num_chips, err; 580 581 if ((gpio_mockup_num_ranges % 2) || 582 (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES)) 583 return -EINVAL; 584 585 /* Each chip is described by two values. */ 586 num_chips = gpio_mockup_num_ranges / 2; 587 588 /* 589 * The second value in the <base GPIO - number of GPIOS> pair must 590 * always be greater than 0. 591 */ 592 for (i = 0; i < num_chips; i++) { 593 if (gpio_mockup_range_ngpio(i) < 0) 594 return -EINVAL; 595 } 596 597 gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL); 598 599 err = platform_driver_register(&gpio_mockup_driver); 600 if (err) { 601 pr_err("error registering platform driver\n"); 602 debugfs_remove_recursive(gpio_mockup_dbg_dir); 603 return err; 604 } 605 606 for (i = 0; i < num_chips; i++) { 607 err = gpio_mockup_register_chip(i); 608 if (err) { 609 platform_driver_unregister(&gpio_mockup_driver); 610 gpio_mockup_unregister_pdevs(); 611 debugfs_remove_recursive(gpio_mockup_dbg_dir); 612 return err; 613 } 614 } 615 616 return 0; 617 } 618 619 static void __exit gpio_mockup_exit(void) 620 { 621 gpio_mockup_unregister_pdevs(); 622 debugfs_remove_recursive(gpio_mockup_dbg_dir); 623 platform_driver_unregister(&gpio_mockup_driver); 624 } 625 626 module_init(gpio_mockup_init); 627 module_exit(gpio_mockup_exit); 628 629 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>"); 630 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>"); 631 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>"); 632 MODULE_DESCRIPTION("GPIO Testing driver"); 633 MODULE_LICENSE("GPL v2"); 634