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