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/debugfs.h> 13 #include <linux/gpio/driver.h> 14 #include <linux/interrupt.h> 15 #include <linux/irq.h> 16 #include <linux/irq_sim.h> 17 #include <linux/irqdomain.h> 18 #include <linux/mod_devicetable.h> 19 #include <linux/module.h> 20 #include <linux/platform_device.h> 21 #include <linux/property.h> 22 #include <linux/slab.h> 23 #include <linux/string_helpers.h> 24 #include <linux/uaccess.h> 25 26 #include "gpiolib.h" 27 28 #define GPIO_MOCKUP_MAX_GC 10 29 /* 30 * We're storing two values per chip: the GPIO base and the number 31 * of GPIO lines. 32 */ 33 #define GPIO_MOCKUP_MAX_RANGES (GPIO_MOCKUP_MAX_GC * 2) 34 /* Maximum of four properties + the sentinel. */ 35 #define GPIO_MOCKUP_MAX_PROP 5 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_domain *irq_sim_domain; 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 int curr, irq, irq_type, ret = 0; 148 struct gpio_desc *desc; 149 struct gpio_chip *gc; 150 151 gc = &chip->gc; 152 desc = &gc->gpiodev->descs[offset]; 153 154 mutex_lock(&chip->lock); 155 156 if (test_bit(FLAG_REQUESTED, &desc->flags) && 157 !test_bit(FLAG_IS_OUT, &desc->flags)) { 158 curr = __gpio_mockup_get(chip, offset); 159 if (curr == value) 160 goto out; 161 162 irq = irq_find_mapping(chip->irq_sim_domain, offset); 163 if (!irq) 164 /* 165 * This is fine - it just means, nobody is listening 166 * for interrupts on this line, otherwise 167 * irq_create_mapping() would have been called from 168 * the to_irq() callback. 169 */ 170 goto set_value; 171 172 irq_type = irq_get_trigger_type(irq); 173 174 if ((value == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) || 175 (value == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING))) { 176 ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, 177 true); 178 if (ret) 179 goto out; 180 } 181 } 182 183 set_value: 184 /* Change the value unless we're actively driving the line. */ 185 if (!test_bit(FLAG_REQUESTED, &desc->flags) || 186 !test_bit(FLAG_IS_OUT, &desc->flags)) 187 __gpio_mockup_set(chip, offset, value); 188 189 out: 190 chip->lines[offset].pull = value; 191 mutex_unlock(&chip->lock); 192 return ret; 193 } 194 195 static int gpio_mockup_set_config(struct gpio_chip *gc, 196 unsigned int offset, unsigned long config) 197 { 198 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 199 200 switch (pinconf_to_config_param(config)) { 201 case PIN_CONFIG_BIAS_PULL_UP: 202 return gpio_mockup_apply_pull(chip, offset, 1); 203 case PIN_CONFIG_BIAS_PULL_DOWN: 204 return gpio_mockup_apply_pull(chip, offset, 0); 205 default: 206 break; 207 } 208 return -ENOTSUPP; 209 } 210 211 static int gpio_mockup_dirout(struct gpio_chip *gc, 212 unsigned int offset, int value) 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_OUT; 218 __gpio_mockup_set(chip, offset, value); 219 mutex_unlock(&chip->lock); 220 221 return 0; 222 } 223 224 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset) 225 { 226 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 227 228 mutex_lock(&chip->lock); 229 chip->lines[offset].dir = GPIO_LINE_DIRECTION_IN; 230 mutex_unlock(&chip->lock); 231 232 return 0; 233 } 234 235 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset) 236 { 237 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 238 int direction; 239 240 mutex_lock(&chip->lock); 241 direction = chip->lines[offset].dir; 242 mutex_unlock(&chip->lock); 243 244 return direction; 245 } 246 247 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset) 248 { 249 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 250 251 return irq_create_mapping(chip->irq_sim_domain, offset); 252 } 253 254 static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset) 255 { 256 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 257 258 __gpio_mockup_set(chip, offset, chip->lines[offset].pull); 259 } 260 261 static ssize_t gpio_mockup_debugfs_read(struct file *file, 262 char __user *usr_buf, 263 size_t size, loff_t *ppos) 264 { 265 struct gpio_mockup_dbgfs_private *priv; 266 struct gpio_mockup_chip *chip; 267 struct seq_file *sfile; 268 struct gpio_chip *gc; 269 int val, cnt; 270 char buf[3]; 271 272 if (*ppos != 0) 273 return 0; 274 275 sfile = file->private_data; 276 priv = sfile->private; 277 chip = priv->chip; 278 gc = &chip->gc; 279 280 val = gpio_mockup_get(gc, priv->offset); 281 cnt = snprintf(buf, sizeof(buf), "%d\n", val); 282 283 return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt); 284 } 285 286 static ssize_t gpio_mockup_debugfs_write(struct file *file, 287 const char __user *usr_buf, 288 size_t size, loff_t *ppos) 289 { 290 struct gpio_mockup_dbgfs_private *priv; 291 int rv, val; 292 struct seq_file *sfile; 293 294 if (*ppos != 0) 295 return -EINVAL; 296 297 rv = kstrtoint_from_user(usr_buf, size, 0, &val); 298 if (rv) 299 return rv; 300 if (val != 0 && val != 1) 301 return -EINVAL; 302 303 sfile = file->private_data; 304 priv = sfile->private; 305 rv = gpio_mockup_apply_pull(priv->chip, priv->offset, val); 306 if (rv) 307 return rv; 308 309 return size; 310 } 311 312 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file) 313 { 314 return single_open(file, NULL, inode->i_private); 315 } 316 317 /* 318 * Each mockup chip is represented by a directory named after the chip's device 319 * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by 320 * a file using the line's offset as the name under the chip's directory. 321 * 322 * Reading from the line's file yields the current *value*, writing to the 323 * line's file changes the current *pull*. Default pull for mockup lines is 324 * down. 325 * 326 * Examples: 327 * - when a line pulled down is requested in output mode and driven high, its 328 * value will return to 0 once it's released 329 * - when the line is requested in output mode and driven high, writing 0 to 330 * the corresponding debugfs file will change the pull to down but the 331 * reported value will still be 1 until the line is released 332 * - line requested in input mode always reports the same value as its pull 333 * configuration 334 * - when the line is requested in input mode and monitored for events, writing 335 * the same value to the debugfs file will be a noop, while writing the 336 * opposite value will generate a dummy interrupt with an appropriate edge 337 */ 338 static const struct file_operations gpio_mockup_debugfs_ops = { 339 .owner = THIS_MODULE, 340 .open = gpio_mockup_debugfs_open, 341 .read = gpio_mockup_debugfs_read, 342 .write = gpio_mockup_debugfs_write, 343 .llseek = no_llseek, 344 .release = single_release, 345 }; 346 347 static void gpio_mockup_debugfs_setup(struct device *dev, 348 struct gpio_mockup_chip *chip) 349 { 350 struct gpio_mockup_dbgfs_private *priv; 351 struct gpio_chip *gc; 352 const char *devname; 353 char *name; 354 int i; 355 356 gc = &chip->gc; 357 devname = dev_name(&gc->gpiodev->dev); 358 359 chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir); 360 361 for (i = 0; i < gc->ngpio; i++) { 362 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i); 363 if (!name) 364 return; 365 366 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 367 if (!priv) 368 return; 369 370 priv->chip = chip; 371 priv->offset = i; 372 priv->desc = &gc->gpiodev->descs[i]; 373 374 debugfs_create_file(name, 0200, chip->dbg_dir, priv, 375 &gpio_mockup_debugfs_ops); 376 } 377 } 378 379 static void gpio_mockup_dispose_mappings(void *data) 380 { 381 struct gpio_mockup_chip *chip = data; 382 struct gpio_chip *gc = &chip->gc; 383 int i, irq; 384 385 for (i = 0; i < gc->ngpio; i++) { 386 irq = irq_find_mapping(chip->irq_sim_domain, i); 387 if (irq) 388 irq_dispose_mapping(irq); 389 } 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-label", &name); 412 if (rv) 413 name = dev_name(dev); 414 415 chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL); 416 if (!chip) 417 return -ENOMEM; 418 419 mutex_init(&chip->lock); 420 421 gc = &chip->gc; 422 gc->base = base; 423 gc->ngpio = ngpio; 424 gc->label = name; 425 gc->owner = THIS_MODULE; 426 gc->parent = dev; 427 gc->get = gpio_mockup_get; 428 gc->set = gpio_mockup_set; 429 gc->get_multiple = gpio_mockup_get_multiple; 430 gc->set_multiple = gpio_mockup_set_multiple; 431 gc->direction_output = gpio_mockup_dirout; 432 gc->direction_input = gpio_mockup_dirin; 433 gc->get_direction = gpio_mockup_get_direction; 434 gc->set_config = gpio_mockup_set_config; 435 gc->to_irq = gpio_mockup_to_irq; 436 gc->free = gpio_mockup_free; 437 438 chip->lines = devm_kcalloc(dev, gc->ngpio, 439 sizeof(*chip->lines), GFP_KERNEL); 440 if (!chip->lines) 441 return -ENOMEM; 442 443 for (i = 0; i < gc->ngpio; i++) 444 chip->lines[i].dir = GPIO_LINE_DIRECTION_IN; 445 446 chip->irq_sim_domain = devm_irq_domain_create_sim(dev, NULL, 447 gc->ngpio); 448 if (IS_ERR(chip->irq_sim_domain)) 449 return PTR_ERR(chip->irq_sim_domain); 450 451 rv = devm_add_action_or_reset(dev, gpio_mockup_dispose_mappings, chip); 452 if (rv) 453 return rv; 454 455 rv = devm_gpiochip_add_data(dev, &chip->gc, chip); 456 if (rv) 457 return rv; 458 459 gpio_mockup_debugfs_setup(dev, chip); 460 461 return 0; 462 } 463 464 static const struct of_device_id gpio_mockup_of_match[] = { 465 { .compatible = "gpio-mockup", }, 466 {}, 467 }; 468 MODULE_DEVICE_TABLE(of, gpio_mockup_of_match); 469 470 static struct platform_driver gpio_mockup_driver = { 471 .driver = { 472 .name = "gpio-mockup", 473 .of_match_table = gpio_mockup_of_match, 474 }, 475 .probe = gpio_mockup_probe, 476 }; 477 478 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC]; 479 480 static void gpio_mockup_unregister_pdevs(void) 481 { 482 int i; 483 484 for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) 485 platform_device_unregister(gpio_mockup_pdevs[i]); 486 } 487 488 static __init char **gpio_mockup_make_line_names(const char *label, 489 unsigned int num_lines) 490 { 491 unsigned int i; 492 char **names; 493 494 names = kcalloc(num_lines + 1, sizeof(char *), GFP_KERNEL); 495 if (!names) 496 return NULL; 497 498 for (i = 0; i < num_lines; i++) { 499 names[i] = kasprintf(GFP_KERNEL, "%s-%u", label, i); 500 if (!names[i]) { 501 kfree_strarray(names, i); 502 return NULL; 503 } 504 } 505 506 return names; 507 } 508 509 static int __init gpio_mockup_register_chip(int idx) 510 { 511 struct property_entry properties[GPIO_MOCKUP_MAX_PROP]; 512 struct platform_device_info pdevinfo; 513 struct platform_device *pdev; 514 char **line_names = NULL; 515 char chip_label[32]; 516 int prop = 0, base; 517 u16 ngpio; 518 519 memset(properties, 0, sizeof(properties)); 520 memset(&pdevinfo, 0, sizeof(pdevinfo)); 521 522 snprintf(chip_label, sizeof(chip_label), "gpio-mockup-%c", idx + 'A'); 523 properties[prop++] = PROPERTY_ENTRY_STRING("chip-label", chip_label); 524 525 base = gpio_mockup_range_base(idx); 526 if (base >= 0) 527 properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", base); 528 529 ngpio = base < 0 ? gpio_mockup_range_ngpio(idx) 530 : gpio_mockup_range_ngpio(idx) - base; 531 properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio); 532 533 if (gpio_mockup_named_lines) { 534 line_names = gpio_mockup_make_line_names(chip_label, ngpio); 535 if (!line_names) 536 return -ENOMEM; 537 538 properties[prop++] = PROPERTY_ENTRY_STRING_ARRAY_LEN( 539 "gpio-line-names", line_names, ngpio); 540 } 541 542 pdevinfo.name = "gpio-mockup"; 543 pdevinfo.id = idx; 544 pdevinfo.properties = properties; 545 546 pdev = platform_device_register_full(&pdevinfo); 547 kfree_strarray(line_names, ngpio); 548 if (IS_ERR(pdev)) { 549 pr_err("error registering device"); 550 return PTR_ERR(pdev); 551 } 552 553 gpio_mockup_pdevs[idx] = pdev; 554 555 return 0; 556 } 557 558 static int __init gpio_mockup_init(void) 559 { 560 int i, num_chips, err; 561 562 if ((gpio_mockup_num_ranges % 2) || 563 (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES)) 564 return -EINVAL; 565 566 /* Each chip is described by two values. */ 567 num_chips = gpio_mockup_num_ranges / 2; 568 569 /* 570 * The second value in the <base GPIO - number of GPIOS> pair must 571 * always be greater than 0. 572 */ 573 for (i = 0; i < num_chips; i++) { 574 if (gpio_mockup_range_ngpio(i) < 0) 575 return -EINVAL; 576 } 577 578 gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL); 579 580 err = platform_driver_register(&gpio_mockup_driver); 581 if (err) { 582 pr_err("error registering platform driver\n"); 583 debugfs_remove_recursive(gpio_mockup_dbg_dir); 584 return err; 585 } 586 587 for (i = 0; i < num_chips; i++) { 588 err = gpio_mockup_register_chip(i); 589 if (err) { 590 platform_driver_unregister(&gpio_mockup_driver); 591 gpio_mockup_unregister_pdevs(); 592 debugfs_remove_recursive(gpio_mockup_dbg_dir); 593 return err; 594 } 595 } 596 597 return 0; 598 } 599 600 static void __exit gpio_mockup_exit(void) 601 { 602 debugfs_remove_recursive(gpio_mockup_dbg_dir); 603 platform_driver_unregister(&gpio_mockup_driver); 604 gpio_mockup_unregister_pdevs(); 605 } 606 607 module_init(gpio_mockup_init); 608 module_exit(gpio_mockup_exit); 609 610 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>"); 611 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>"); 612 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>"); 613 MODULE_DESCRIPTION("GPIO Testing driver"); 614 MODULE_LICENSE("GPL v2"); 615