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 char buf[3]; 208 int val, rv; 209 210 if (*ppos != 0) 211 return 0; 212 213 sfile = file->private_data; 214 priv = sfile->private; 215 chip = priv->chip; 216 gc = &chip->gc; 217 218 val = gpio_mockup_get(gc, priv->offset); 219 snprintf(buf, sizeof(buf), "%d\n", val); 220 221 rv = copy_to_user(usr_buf, buf, sizeof(buf)); 222 if (rv) 223 return rv; 224 225 return sizeof(buf) - 1; 226 } 227 228 static ssize_t gpio_mockup_debugfs_write(struct file *file, 229 const char __user *usr_buf, 230 size_t size, loff_t *ppos) 231 { 232 struct gpio_mockup_dbgfs_private *priv; 233 int rv, val, curr, irq, irq_type; 234 struct gpio_mockup_chip *chip; 235 struct seq_file *sfile; 236 struct gpio_desc *desc; 237 struct gpio_chip *gc; 238 struct irq_sim *sim; 239 240 if (*ppos != 0) 241 return -EINVAL; 242 243 rv = kstrtoint_from_user(usr_buf, size, 0, &val); 244 if (rv) 245 return rv; 246 if (val != 0 && val != 1) 247 return -EINVAL; 248 249 sfile = file->private_data; 250 priv = sfile->private; 251 chip = priv->chip; 252 gc = &chip->gc; 253 desc = &gc->gpiodev->descs[priv->offset]; 254 sim = &chip->irqsim; 255 256 mutex_lock(&chip->lock); 257 258 if (test_bit(FLAG_REQUESTED, &desc->flags) && 259 !test_bit(FLAG_IS_OUT, &desc->flags)) { 260 curr = __gpio_mockup_get(chip, priv->offset); 261 if (curr == val) 262 goto out; 263 264 irq = irq_sim_irqnum(sim, priv->offset); 265 irq_type = irq_get_trigger_type(irq); 266 267 if ((val == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) || 268 (val == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING))) 269 irq_sim_fire(sim, priv->offset); 270 } 271 272 /* Change the value unless we're actively driving the line. */ 273 if (!test_bit(FLAG_REQUESTED, &desc->flags) || 274 !test_bit(FLAG_IS_OUT, &desc->flags)) 275 __gpio_mockup_set(chip, priv->offset, val); 276 277 out: 278 chip->lines[priv->offset].pull = val; 279 mutex_unlock(&chip->lock); 280 281 return size; 282 } 283 284 static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file) 285 { 286 return single_open(file, NULL, inode->i_private); 287 } 288 289 /* 290 * Each mockup chip is represented by a directory named after the chip's device 291 * name under /sys/kernel/debug/gpio-mockup/. Each line is represented by 292 * a file using the line's offset as the name under the chip's directory. 293 * 294 * Reading from the line's file yields the current *value*, writing to the 295 * line's file changes the current *pull*. Default pull for mockup lines is 296 * down. 297 * 298 * Examples: 299 * - when a line pulled down is requested in output mode and driven high, its 300 * value will return to 0 once it's released 301 * - when the line is requested in output mode and driven high, writing 0 to 302 * the corresponding debugfs file will change the pull to down but the 303 * reported value will still be 1 until the line is released 304 * - line requested in input mode always reports the same value as its pull 305 * configuration 306 * - when the line is requested in input mode and monitored for events, writing 307 * the same value to the debugfs file will be a noop, while writing the 308 * opposite value will generate a dummy interrupt with an appropriate edge 309 */ 310 static const struct file_operations gpio_mockup_debugfs_ops = { 311 .owner = THIS_MODULE, 312 .open = gpio_mockup_debugfs_open, 313 .read = gpio_mockup_debugfs_read, 314 .write = gpio_mockup_debugfs_write, 315 .llseek = no_llseek, 316 }; 317 318 static void gpio_mockup_debugfs_setup(struct device *dev, 319 struct gpio_mockup_chip *chip) 320 { 321 struct gpio_mockup_dbgfs_private *priv; 322 struct dentry *evfile; 323 struct gpio_chip *gc; 324 const char *devname; 325 char *name; 326 int i; 327 328 gc = &chip->gc; 329 devname = dev_name(&gc->gpiodev->dev); 330 331 chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir); 332 if (IS_ERR_OR_NULL(chip->dbg_dir)) 333 goto err; 334 335 for (i = 0; i < gc->ngpio; i++) { 336 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i); 337 if (!name) 338 goto err; 339 340 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 341 if (!priv) 342 goto err; 343 344 priv->chip = chip; 345 priv->offset = i; 346 priv->desc = &gc->gpiodev->descs[i]; 347 348 evfile = debugfs_create_file(name, 0200, chip->dbg_dir, priv, 349 &gpio_mockup_debugfs_ops); 350 if (IS_ERR_OR_NULL(evfile)) 351 goto err; 352 } 353 354 return; 355 356 err: 357 dev_err(dev, "error creating debugfs files\n"); 358 } 359 360 static int gpio_mockup_name_lines(struct device *dev, 361 struct gpio_mockup_chip *chip) 362 { 363 struct gpio_chip *gc = &chip->gc; 364 char **names; 365 int i; 366 367 names = devm_kcalloc(dev, gc->ngpio, sizeof(char *), GFP_KERNEL); 368 if (!names) 369 return -ENOMEM; 370 371 for (i = 0; i < gc->ngpio; i++) { 372 names[i] = devm_kasprintf(dev, GFP_KERNEL, 373 "%s-%d", gc->label, i); 374 if (!names[i]) 375 return -ENOMEM; 376 } 377 378 gc->names = (const char *const *)names; 379 380 return 0; 381 } 382 383 static int gpio_mockup_probe(struct platform_device *pdev) 384 { 385 struct gpio_mockup_chip *chip; 386 struct gpio_chip *gc; 387 struct device *dev; 388 const char *name; 389 int rv, base; 390 u16 ngpio; 391 392 dev = &pdev->dev; 393 394 rv = device_property_read_u32(dev, "gpio-base", &base); 395 if (rv) 396 base = -1; 397 398 rv = device_property_read_u16(dev, "nr-gpios", &ngpio); 399 if (rv) 400 return rv; 401 402 rv = device_property_read_string(dev, "chip-name", &name); 403 if (rv) 404 name = NULL; 405 406 chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL); 407 if (!chip) 408 return -ENOMEM; 409 410 if (!name) { 411 name = devm_kasprintf(dev, GFP_KERNEL, 412 "%s-%c", pdev->name, pdev->id + 'A'); 413 if (!name) 414 return -ENOMEM; 415 } 416 417 mutex_init(&chip->lock); 418 419 gc = &chip->gc; 420 gc->base = base; 421 gc->ngpio = ngpio; 422 gc->label = name; 423 gc->owner = THIS_MODULE; 424 gc->parent = dev; 425 gc->get = gpio_mockup_get; 426 gc->set = gpio_mockup_set; 427 gc->get_multiple = gpio_mockup_get_multiple; 428 gc->set_multiple = gpio_mockup_set_multiple; 429 gc->direction_output = gpio_mockup_dirout; 430 gc->direction_input = gpio_mockup_dirin; 431 gc->get_direction = gpio_mockup_get_direction; 432 gc->to_irq = gpio_mockup_to_irq; 433 gc->free = gpio_mockup_free; 434 435 chip->lines = devm_kcalloc(dev, gc->ngpio, 436 sizeof(*chip->lines), GFP_KERNEL); 437 if (!chip->lines) 438 return -ENOMEM; 439 440 if (device_property_read_bool(dev, "named-gpio-lines")) { 441 rv = gpio_mockup_name_lines(dev, chip); 442 if (rv) 443 return rv; 444 } 445 446 rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio); 447 if (rv < 0) 448 return rv; 449 450 rv = devm_gpiochip_add_data(dev, &chip->gc, chip); 451 if (rv) 452 return rv; 453 454 if (!IS_ERR_OR_NULL(gpio_mockup_dbg_dir)) 455 gpio_mockup_debugfs_setup(dev, chip); 456 457 return 0; 458 } 459 460 static struct platform_driver gpio_mockup_driver = { 461 .driver = { 462 .name = GPIO_MOCKUP_NAME, 463 }, 464 .probe = gpio_mockup_probe, 465 }; 466 467 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC]; 468 469 static void gpio_mockup_unregister_pdevs(void) 470 { 471 struct platform_device *pdev; 472 int i; 473 474 for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) { 475 pdev = gpio_mockup_pdevs[i]; 476 477 if (pdev) 478 platform_device_unregister(pdev); 479 } 480 } 481 482 static int __init gpio_mockup_init(void) 483 { 484 struct property_entry properties[GPIO_MOCKUP_MAX_PROP]; 485 int i, prop, num_chips, err = 0, base; 486 struct platform_device_info pdevinfo; 487 struct platform_device *pdev; 488 u16 ngpio; 489 490 if ((gpio_mockup_num_ranges < 2) || 491 (gpio_mockup_num_ranges % 2) || 492 (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES)) 493 return -EINVAL; 494 495 /* Each chip is described by two values. */ 496 num_chips = gpio_mockup_num_ranges / 2; 497 498 /* 499 * The second value in the <base GPIO - number of GPIOS> pair must 500 * always be greater than 0. 501 */ 502 for (i = 0; i < num_chips; i++) { 503 if (gpio_mockup_range_ngpio(i) < 0) 504 return -EINVAL; 505 } 506 507 gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL); 508 if (IS_ERR_OR_NULL(gpio_mockup_dbg_dir)) 509 gpio_mockup_err("error creating debugfs directory\n"); 510 511 err = platform_driver_register(&gpio_mockup_driver); 512 if (err) { 513 gpio_mockup_err("error registering platform driver\n"); 514 return err; 515 } 516 517 for (i = 0; i < num_chips; i++) { 518 memset(properties, 0, sizeof(properties)); 519 memset(&pdevinfo, 0, sizeof(pdevinfo)); 520 prop = 0; 521 522 base = gpio_mockup_range_base(i); 523 if (base >= 0) 524 properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", 525 base); 526 527 ngpio = base < 0 ? gpio_mockup_range_ngpio(i) 528 : gpio_mockup_range_ngpio(i) - base; 529 properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio); 530 531 if (gpio_mockup_named_lines) 532 properties[prop++] = PROPERTY_ENTRY_BOOL( 533 "named-gpio-lines"); 534 535 pdevinfo.name = GPIO_MOCKUP_NAME; 536 pdevinfo.id = i; 537 pdevinfo.properties = properties; 538 539 pdev = platform_device_register_full(&pdevinfo); 540 if (IS_ERR(pdev)) { 541 gpio_mockup_err("error registering device"); 542 platform_driver_unregister(&gpio_mockup_driver); 543 gpio_mockup_unregister_pdevs(); 544 return PTR_ERR(pdev); 545 } 546 547 gpio_mockup_pdevs[i] = pdev; 548 } 549 550 return 0; 551 } 552 553 static void __exit gpio_mockup_exit(void) 554 { 555 debugfs_remove_recursive(gpio_mockup_dbg_dir); 556 platform_driver_unregister(&gpio_mockup_driver); 557 gpio_mockup_unregister_pdevs(); 558 } 559 560 module_init(gpio_mockup_init); 561 module_exit(gpio_mockup_exit); 562 563 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>"); 564 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>"); 565 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>"); 566 MODULE_DESCRIPTION("GPIO Testing driver"); 567 MODULE_LICENSE("GPL v2"); 568