1 // SPDX-License-Identifier: GPL-2.0+ 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/init.h> 11 #include <linux/module.h> 12 #include <linux/gpio/driver.h> 13 #include <linux/gpio/consumer.h> 14 #include <linux/platform_device.h> 15 #include <linux/slab.h> 16 #include <linux/interrupt.h> 17 #include <linux/irq.h> 18 #include <linux/irq_sim.h> 19 #include <linux/debugfs.h> 20 #include <linux/uaccess.h> 21 #include <linux/property.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 enum { 38 GPIO_MOCKUP_DIR_IN = 0, 39 GPIO_MOCKUP_DIR_OUT = 1, 40 }; 41 42 /* 43 * struct gpio_pin_status - structure describing a GPIO status 44 * @dir: Configures direction of gpio as "in" or "out", 0=in, 1=out 45 * @value: Configures status of the gpio as 0(low) or 1(high) 46 */ 47 struct gpio_mockup_line_status { 48 int dir; 49 int value; 50 int pull; 51 }; 52 53 struct gpio_mockup_chip { 54 struct gpio_chip gc; 55 struct gpio_mockup_line_status *lines; 56 struct irq_sim irqsim; 57 struct dentry *dbg_dir; 58 struct mutex lock; 59 }; 60 61 struct gpio_mockup_dbgfs_private { 62 struct gpio_mockup_chip *chip; 63 struct gpio_desc *desc; 64 unsigned int offset; 65 }; 66 67 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES]; 68 static int gpio_mockup_num_ranges; 69 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400); 70 71 static bool gpio_mockup_named_lines; 72 module_param_named(gpio_mockup_named_lines, 73 gpio_mockup_named_lines, bool, 0400); 74 75 static struct dentry *gpio_mockup_dbg_dir; 76 77 static int gpio_mockup_range_base(unsigned int index) 78 { 79 return gpio_mockup_ranges[index * 2]; 80 } 81 82 static int gpio_mockup_range_ngpio(unsigned int index) 83 { 84 return gpio_mockup_ranges[index * 2 + 1]; 85 } 86 87 static int __gpio_mockup_get(struct gpio_mockup_chip *chip, 88 unsigned int offset) 89 { 90 return chip->lines[offset].value; 91 } 92 93 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset) 94 { 95 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 96 int val; 97 98 mutex_lock(&chip->lock); 99 val = __gpio_mockup_get(chip, offset); 100 mutex_unlock(&chip->lock); 101 102 return val; 103 } 104 105 static int gpio_mockup_get_multiple(struct gpio_chip *gc, 106 unsigned long *mask, unsigned long *bits) 107 { 108 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 109 unsigned int bit, val; 110 111 mutex_lock(&chip->lock); 112 for_each_set_bit(bit, mask, gc->ngpio) { 113 val = __gpio_mockup_get(chip, bit); 114 __assign_bit(bit, bits, val); 115 } 116 mutex_unlock(&chip->lock); 117 118 return 0; 119 } 120 121 static void __gpio_mockup_set(struct gpio_mockup_chip *chip, 122 unsigned int offset, int value) 123 { 124 chip->lines[offset].value = !!value; 125 } 126 127 static void gpio_mockup_set(struct gpio_chip *gc, 128 unsigned int offset, int value) 129 { 130 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 131 132 mutex_lock(&chip->lock); 133 __gpio_mockup_set(chip, offset, value); 134 mutex_unlock(&chip->lock); 135 } 136 137 static void gpio_mockup_set_multiple(struct gpio_chip *gc, 138 unsigned long *mask, unsigned long *bits) 139 { 140 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 141 unsigned int bit; 142 143 mutex_lock(&chip->lock); 144 for_each_set_bit(bit, mask, gc->ngpio) 145 __gpio_mockup_set(chip, bit, test_bit(bit, bits)); 146 mutex_unlock(&chip->lock); 147 } 148 149 static int gpio_mockup_dirout(struct gpio_chip *gc, 150 unsigned int offset, int value) 151 { 152 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 153 154 mutex_lock(&chip->lock); 155 chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT; 156 __gpio_mockup_set(chip, offset, value); 157 mutex_unlock(&chip->lock); 158 159 return 0; 160 } 161 162 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset) 163 { 164 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 165 166 mutex_lock(&chip->lock); 167 chip->lines[offset].dir = GPIO_MOCKUP_DIR_IN; 168 mutex_unlock(&chip->lock); 169 170 return 0; 171 } 172 173 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset) 174 { 175 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 176 int direction; 177 178 mutex_lock(&chip->lock); 179 direction = !chip->lines[offset].dir; 180 mutex_unlock(&chip->lock); 181 182 return direction; 183 } 184 185 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset) 186 { 187 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 188 189 return irq_sim_irqnum(&chip->irqsim, offset); 190 } 191 192 static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset) 193 { 194 struct gpio_mockup_chip *chip = gpiochip_get_data(gc); 195 196 __gpio_mockup_set(chip, offset, chip->lines[offset].pull); 197 } 198 199 static ssize_t gpio_mockup_debugfs_read(struct file *file, 200 char __user *usr_buf, 201 size_t size, loff_t *ppos) 202 { 203 struct gpio_mockup_dbgfs_private *priv; 204 struct gpio_mockup_chip *chip; 205 struct seq_file *sfile; 206 struct gpio_chip *gc; 207 int val, rv, cnt; 208 char buf[3]; 209 210 211 if (*ppos != 0) 212 return 0; 213 214 sfile = file->private_data; 215 priv = sfile->private; 216 chip = priv->chip; 217 gc = &chip->gc; 218 219 val = gpio_mockup_get(gc, priv->offset); 220 cnt = snprintf(buf, sizeof(buf), "%d\n", val); 221 222 rv = copy_to_user(usr_buf, buf, cnt); 223 if (rv) 224 return rv; 225 226 *ppos += cnt; 227 return cnt; 228 } 229 230 static ssize_t gpio_mockup_debugfs_write(struct file *file, 231 const char __user *usr_buf, 232 size_t size, loff_t *ppos) 233 { 234 struct gpio_mockup_dbgfs_private *priv; 235 int rv, val, curr, irq, irq_type; 236 struct gpio_mockup_chip *chip; 237 struct seq_file *sfile; 238 struct gpio_desc *desc; 239 struct gpio_chip *gc; 240 struct irq_sim *sim; 241 242 if (*ppos != 0) 243 return -EINVAL; 244 245 rv = kstrtoint_from_user(usr_buf, size, 0, &val); 246 if (rv) 247 return rv; 248 if (val != 0 && val != 1) 249 return -EINVAL; 250 251 sfile = file->private_data; 252 priv = sfile->private; 253 chip = priv->chip; 254 gc = &chip->gc; 255 desc = &gc->gpiodev->descs[priv->offset]; 256 sim = &chip->irqsim; 257 258 mutex_lock(&chip->lock); 259 260 if (test_bit(FLAG_REQUESTED, &desc->flags) && 261 !test_bit(FLAG_IS_OUT, &desc->flags)) { 262 curr = __gpio_mockup_get(chip, priv->offset); 263 if (curr == val) 264 goto out; 265 266 irq = irq_sim_irqnum(sim, priv->offset); 267 irq_type = irq_get_trigger_type(irq); 268 269 if ((val == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) || 270 (val == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING))) 271 irq_sim_fire(sim, priv->offset); 272 } 273 274 /* Change the value unless we're actively driving the line. */ 275 if (!test_bit(FLAG_REQUESTED, &desc->flags) || 276 !test_bit(FLAG_IS_OUT, &desc->flags)) 277 __gpio_mockup_set(chip, priv->offset, val); 278 279 out: 280 chip->lines[priv->offset].pull = val; 281 mutex_unlock(&chip->lock); 282 283 return size; 284 } 285 286 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file) 287 { 288 return single_open(file, NULL, inode->i_private); 289 } 290 291 /* 292 * Each mockup chip is represented by a directory named after the chip's device 293 * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by 294 * a file using the line's offset as the name under the chip's directory. 295 * 296 * Reading from the line's file yields the current *value*, writing to the 297 * line's file changes the current *pull*. Default pull for mockup lines is 298 * down. 299 * 300 * Examples: 301 * - when a line pulled down is requested in output mode and driven high, its 302 * value will return to 0 once it's released 303 * - when the line is requested in output mode and driven high, writing 0 to 304 * the corresponding debugfs file will change the pull to down but the 305 * reported value will still be 1 until the line is released 306 * - line requested in input mode always reports the same value as its pull 307 * configuration 308 * - when the line is requested in input mode and monitored for events, writing 309 * the same value to the debugfs file will be a noop, while writing the 310 * opposite value will generate a dummy interrupt with an appropriate edge 311 */ 312 static const struct file_operations gpio_mockup_debugfs_ops = { 313 .owner = THIS_MODULE, 314 .open = gpio_mockup_debugfs_open, 315 .read = gpio_mockup_debugfs_read, 316 .write = gpio_mockup_debugfs_write, 317 .llseek = no_llseek, 318 }; 319 320 static void gpio_mockup_debugfs_setup(struct device *dev, 321 struct gpio_mockup_chip *chip) 322 { 323 struct gpio_mockup_dbgfs_private *priv; 324 struct dentry *evfile; 325 struct gpio_chip *gc; 326 const char *devname; 327 char *name; 328 int i; 329 330 gc = &chip->gc; 331 devname = dev_name(&gc->gpiodev->dev); 332 333 chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir); 334 if (IS_ERR_OR_NULL(chip->dbg_dir)) 335 goto err; 336 337 for (i = 0; i < gc->ngpio; i++) { 338 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i); 339 if (!name) 340 goto err; 341 342 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 343 if (!priv) 344 goto err; 345 346 priv->chip = chip; 347 priv->offset = i; 348 priv->desc = &gc->gpiodev->descs[i]; 349 350 evfile = debugfs_create_file(name, 0200, chip->dbg_dir, priv, 351 &gpio_mockup_debugfs_ops); 352 if (IS_ERR_OR_NULL(evfile)) 353 goto err; 354 } 355 356 return; 357 358 err: 359 dev_err(dev, "error creating debugfs files\n"); 360 } 361 362 static int gpio_mockup_name_lines(struct device *dev, 363 struct gpio_mockup_chip *chip) 364 { 365 struct gpio_chip *gc = &chip->gc; 366 char **names; 367 int i; 368 369 names = devm_kcalloc(dev, gc->ngpio, sizeof(char *), GFP_KERNEL); 370 if (!names) 371 return -ENOMEM; 372 373 for (i = 0; i < gc->ngpio; i++) { 374 names[i] = devm_kasprintf(dev, GFP_KERNEL, 375 "%s-%d", gc->label, i); 376 if (!names[i]) 377 return -ENOMEM; 378 } 379 380 gc->names = (const char *const *)names; 381 382 return 0; 383 } 384 385 static int gpio_mockup_probe(struct platform_device *pdev) 386 { 387 struct gpio_mockup_chip *chip; 388 struct gpio_chip *gc; 389 struct device *dev; 390 const char *name; 391 int rv, base; 392 u16 ngpio; 393 394 dev = &pdev->dev; 395 396 rv = device_property_read_u32(dev, "gpio-base", &base); 397 if (rv) 398 base = -1; 399 400 rv = device_property_read_u16(dev, "nr-gpios", &ngpio); 401 if (rv) 402 return rv; 403 404 rv = device_property_read_string(dev, "chip-name", &name); 405 if (rv) 406 name = NULL; 407 408 chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL); 409 if (!chip) 410 return -ENOMEM; 411 412 if (!name) { 413 name = devm_kasprintf(dev, GFP_KERNEL, 414 "%s-%c", pdev->name, pdev->id + 'A'); 415 if (!name) 416 return -ENOMEM; 417 } 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->to_irq = gpio_mockup_to_irq; 435 gc->free = gpio_mockup_free; 436 437 chip->lines = devm_kcalloc(dev, gc->ngpio, 438 sizeof(*chip->lines), GFP_KERNEL); 439 if (!chip->lines) 440 return -ENOMEM; 441 442 if (device_property_read_bool(dev, "named-gpio-lines")) { 443 rv = gpio_mockup_name_lines(dev, chip); 444 if (rv) 445 return rv; 446 } 447 448 rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio); 449 if (rv < 0) 450 return rv; 451 452 rv = devm_gpiochip_add_data(dev, &chip->gc, chip); 453 if (rv) 454 return rv; 455 456 if (!IS_ERR_OR_NULL(gpio_mockup_dbg_dir)) 457 gpio_mockup_debugfs_setup(dev, chip); 458 459 return 0; 460 } 461 462 static struct platform_driver gpio_mockup_driver = { 463 .driver = { 464 .name = GPIO_MOCKUP_NAME, 465 }, 466 .probe = gpio_mockup_probe, 467 }; 468 469 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC]; 470 471 static void gpio_mockup_unregister_pdevs(void) 472 { 473 struct platform_device *pdev; 474 int i; 475 476 for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) { 477 pdev = gpio_mockup_pdevs[i]; 478 479 if (pdev) 480 platform_device_unregister(pdev); 481 } 482 } 483 484 static int __init gpio_mockup_init(void) 485 { 486 struct property_entry properties[GPIO_MOCKUP_MAX_PROP]; 487 int i, prop, num_chips, err = 0, base; 488 struct platform_device_info pdevinfo; 489 struct platform_device *pdev; 490 u16 ngpio; 491 492 if ((gpio_mockup_num_ranges < 2) || 493 (gpio_mockup_num_ranges % 2) || 494 (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES)) 495 return -EINVAL; 496 497 /* Each chip is described by two values. */ 498 num_chips = gpio_mockup_num_ranges / 2; 499 500 /* 501 * The second value in the <base GPIO - number of GPIOS> pair must 502 * always be greater than 0. 503 */ 504 for (i = 0; i < num_chips; i++) { 505 if (gpio_mockup_range_ngpio(i) < 0) 506 return -EINVAL; 507 } 508 509 gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL); 510 if (IS_ERR_OR_NULL(gpio_mockup_dbg_dir)) 511 gpio_mockup_err("error creating debugfs directory\n"); 512 513 err = platform_driver_register(&gpio_mockup_driver); 514 if (err) { 515 gpio_mockup_err("error registering platform driver\n"); 516 return err; 517 } 518 519 for (i = 0; i < num_chips; i++) { 520 memset(properties, 0, sizeof(properties)); 521 memset(&pdevinfo, 0, sizeof(pdevinfo)); 522 prop = 0; 523 524 base = gpio_mockup_range_base(i); 525 if (base >= 0) 526 properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", 527 base); 528 529 ngpio = base < 0 ? gpio_mockup_range_ngpio(i) 530 : gpio_mockup_range_ngpio(i) - base; 531 properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio); 532 533 if (gpio_mockup_named_lines) 534 properties[prop++] = PROPERTY_ENTRY_BOOL( 535 "named-gpio-lines"); 536 537 pdevinfo.name = GPIO_MOCKUP_NAME; 538 pdevinfo.id = i; 539 pdevinfo.properties = properties; 540 541 pdev = platform_device_register_full(&pdevinfo); 542 if (IS_ERR(pdev)) { 543 gpio_mockup_err("error registering device"); 544 platform_driver_unregister(&gpio_mockup_driver); 545 gpio_mockup_unregister_pdevs(); 546 return PTR_ERR(pdev); 547 } 548 549 gpio_mockup_pdevs[i] = pdev; 550 } 551 552 return 0; 553 } 554 555 static void __exit gpio_mockup_exit(void) 556 { 557 debugfs_remove_recursive(gpio_mockup_dbg_dir); 558 platform_driver_unregister(&gpio_mockup_driver); 559 gpio_mockup_unregister_pdevs(); 560 } 561 562 module_init(gpio_mockup_init); 563 module_exit(gpio_mockup_exit); 564 565 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>"); 566 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>"); 567 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>"); 568 MODULE_DESCRIPTION("GPIO Testing driver"); 569 MODULE_LICENSE("GPL v2"); 570