drivers/gpio/gpio-mockup.c

   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_OUT = 0,
  39         GPIO_MOCKUP_DIR_IN = 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 };
  51
  52 struct gpio_mockup_chip {
  53         struct gpio_chip gc;
  54         struct gpio_mockup_line_status *lines;
  55         struct irq_sim irqsim;
  56         struct dentry *dbg_dir;
  57 };
  58
  59 struct gpio_mockup_dbgfs_private {
  60         struct gpio_mockup_chip *chip;
  61         struct gpio_desc *desc;
  62         int offset;
  63 };
  64
  65 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
  66 static int gpio_mockup_num_ranges;
  67 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
  68
  69 static bool gpio_mockup_named_lines;
  70 module_param_named(gpio_mockup_named_lines,
  71                    gpio_mockup_named_lines, bool, 0400);
  72
  73 static struct dentry *gpio_mockup_dbg_dir;
  74
  75 static int gpio_mockup_range_base(unsigned int index)
  76 {
  77         return gpio_mockup_ranges[index * 2];
  78 }
  79
  80 static int gpio_mockup_range_ngpio(unsigned int index)
  81 {
  82         return gpio_mockup_ranges[index * 2 + 1];
  83 }
  84
  85 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
  86 {
  87         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
  88
  89         return chip->lines[offset].value;
  90 }
  91
  92 static void gpio_mockup_set(struct gpio_chip *gc,
  93                             unsigned int offset, int value)
  94 {
  95         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
  96
  97         chip->lines[offset].value = !!value;
  98 }
  99
 100 static void gpio_mockup_set_multiple(struct gpio_chip *gc,
 101                                      unsigned long *mask, unsigned long *bits)
 102 {
 103         unsigned int bit;
 104
 105         for_each_set_bit(bit, mask, gc->ngpio)
 106                 gpio_mockup_set(gc, bit, test_bit(bit, bits));
 107
 108 }
 109
 110 static int gpio_mockup_dirout(struct gpio_chip *gc,
 111                               unsigned int offset, int value)
 112 {
 113         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 114
 115         gpio_mockup_set(gc, offset, value);
 116         chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT;
 117
 118         return 0;
 119 }
 120
 121 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
 122 {
 123         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 124
 125         chip->lines[offset].dir = GPIO_MOCKUP_DIR_IN;
 126
 127         return 0;
 128 }
 129
 130 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
 131 {
 132         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 133
 134         return chip->lines[offset].dir;
 135 }
 136
 137 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
 138 {
 139         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 140
 141         return irq_sim_irqnum(&chip->irqsim, offset);
 142 }
 143
 144 static ssize_t gpio_mockup_event_write(struct file *file,
 145                                        const char __user *usr_buf,
 146                                        size_t size, loff_t *ppos)
 147 {
 148         struct gpio_mockup_dbgfs_private *priv;
 149         struct gpio_mockup_chip *chip;
 150         struct seq_file *sfile;
 151         struct gpio_desc *desc;
 152         int rv, val;
 153
 154         rv = kstrtoint_from_user(usr_buf, size, 0, &val);
 155         if (rv)
 156                 return rv;
 157         if (val != 0 && val != 1)
 158                 return -EINVAL;
 159
 160         sfile = file->private_data;
 161         priv = sfile->private;
 162         desc = priv->desc;
 163         chip = priv->chip;
 164
 165         gpiod_set_value_cansleep(desc, val);
 166         irq_sim_fire(&chip->irqsim, priv->offset);
 167
 168         return size;
 169 }
 170
 171 static int gpio_mockup_event_open(struct inode *inode, struct file *file)
 172 {
 173         return single_open(file, NULL, inode->i_private);
 174 }
 175
 176 static const struct file_operations gpio_mockup_event_ops = {
 177         .owner = THIS_MODULE,
 178         .open = gpio_mockup_event_open,
 179         .write = gpio_mockup_event_write,
 180         .llseek = no_llseek,
 181 };
 182
 183 static void gpio_mockup_debugfs_setup(struct device *dev,
 184                                       struct gpio_mockup_chip *chip)
 185 {
 186         struct gpio_mockup_dbgfs_private *priv;
 187         struct dentry *evfile, *link;
 188         struct gpio_chip *gc;
 189         const char *devname;
 190         char *name;
 191         int i;
 192
 193         gc = &chip->gc;
 194         devname = dev_name(&gc->gpiodev->dev);
 195
 196         chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
 197         if (IS_ERR_OR_NULL(chip->dbg_dir))
 198                 goto err;
 199
 200         link = debugfs_create_symlink(gc->label, gpio_mockup_dbg_dir, devname);
 201         if (IS_ERR_OR_NULL(link))
 202                 goto err;
 203
 204         for (i = 0; i < gc->ngpio; i++) {
 205                 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
 206                 if (!name)
 207                         goto err;
 208
 209                 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 210                 if (!priv)
 211                         goto err;
 212
 213                 priv->chip = chip;
 214                 priv->offset = i;
 215                 priv->desc = &gc->gpiodev->descs[i];
 216
 217                 evfile = debugfs_create_file(name, 0200, chip->dbg_dir, priv,
 218                                              &gpio_mockup_event_ops);
 219                 if (IS_ERR_OR_NULL(evfile))
 220                         goto err;
 221         }
 222
 223         return;
 224
 225 err:
 226         dev_err(dev, "error creating debugfs event files\n");
 227 }
 228
 229 static int gpio_mockup_name_lines(struct device *dev,
 230                                   struct gpio_mockup_chip *chip)
 231 {
 232         struct gpio_chip *gc = &chip->gc;
 233         char **names;
 234         int i;
 235
 236         names = devm_kcalloc(dev, gc->ngpio, sizeof(char *), GFP_KERNEL);
 237         if (!names)
 238                 return -ENOMEM;
 239
 240         for (i = 0; i < gc->ngpio; i++) {
 241                 names[i] = devm_kasprintf(dev, GFP_KERNEL,
 242                                           "%s-%d", gc->label, i);
 243                 if (!names[i])
 244                         return -ENOMEM;
 245         }
 246
 247         gc->names = (const char *const *)names;
 248
 249         return 0;
 250 }
 251
 252 static int gpio_mockup_probe(struct platform_device *pdev)
 253 {
 254         struct gpio_mockup_chip *chip;
 255         struct gpio_chip *gc;
 256         struct device *dev;
 257         const char *name;
 258         int rv, base;
 259         u16 ngpio;
 260
 261         dev = &pdev->dev;
 262
 263         rv = device_property_read_u32(dev, "gpio-base", &base);
 264         if (rv)
 265                 base = -1;
 266
 267         rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
 268         if (rv)
 269                 return rv;
 270
 271         rv = device_property_read_string(dev, "chip-name", &name);
 272         if (rv)
 273                 name = NULL;
 274
 275         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 276         if (!chip)
 277                 return -ENOMEM;
 278
 279         if (!name) {
 280                 name = devm_kasprintf(dev, GFP_KERNEL,
 281                                       "%s-%c", pdev->name, pdev->id + 'A');
 282                 if (!name)
 283                         return -ENOMEM;
 284         }
 285
 286         gc = &chip->gc;
 287         gc->base = base;
 288         gc->ngpio = ngpio;
 289         gc->label = name;
 290         gc->owner = THIS_MODULE;
 291         gc->parent = dev;
 292         gc->get = gpio_mockup_get;
 293         gc->set = gpio_mockup_set;
 294         gc->set_multiple = gpio_mockup_set_multiple;
 295         gc->direction_output = gpio_mockup_dirout;
 296         gc->direction_input = gpio_mockup_dirin;
 297         gc->get_direction = gpio_mockup_get_direction;
 298         gc->to_irq = gpio_mockup_to_irq;
 299
 300         chip->lines = devm_kcalloc(dev, gc->ngpio,
 301                                    sizeof(*chip->lines), GFP_KERNEL);
 302         if (!chip->lines)
 303                 return -ENOMEM;
 304
 305         if (device_property_read_bool(dev, "named-gpio-lines")) {
 306                 rv = gpio_mockup_name_lines(dev, chip);
 307                 if (rv)
 308                         return rv;
 309         }
 310
 311         rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio);
 312         if (rv < 0)
 313                 return rv;
 314
 315         rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
 316         if (rv)
 317                 return rv;
 318
 319         if (!IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
 320                 gpio_mockup_debugfs_setup(dev, chip);
 321
 322         return 0;
 323 }
 324
 325 static struct platform_driver gpio_mockup_driver = {
 326         .driver = {
 327                 .name = GPIO_MOCKUP_NAME,
 328         },
 329         .probe = gpio_mockup_probe,
 330 };
 331
 332 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
 333
 334 static void gpio_mockup_unregister_pdevs(void)
 335 {
 336         struct platform_device *pdev;
 337         int i;
 338
 339         for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
 340                 pdev = gpio_mockup_pdevs[i];
 341
 342                 if (pdev)
 343                         platform_device_unregister(pdev);
 344         }
 345 }
 346
 347 static int __init gpio_mockup_init(void)
 348 {
 349         struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
 350         int i, prop, num_chips, err = 0, base;
 351         struct platform_device_info pdevinfo;
 352         struct platform_device *pdev;
 353         u16 ngpio;
 354
 355         if ((gpio_mockup_num_ranges < 2) ||
 356             (gpio_mockup_num_ranges % 2) ||
 357             (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
 358                 return -EINVAL;
 359
 360         /* Each chip is described by two values. */
 361         num_chips = gpio_mockup_num_ranges / 2;
 362
 363         /*
 364          * The second value in the <base GPIO - number of GPIOS> pair must
 365          * always be greater than 0.
 366          */
 367         for (i = 0; i < num_chips; i++) {
 368                 if (gpio_mockup_range_ngpio(i) < 0)
 369                         return -EINVAL;
 370         }
 371
 372         gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup-event", NULL);
 373         if (IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
 374                 gpio_mockup_err("error creating debugfs directory\n");
 375
 376         err = platform_driver_register(&gpio_mockup_driver);
 377         if (err) {
 378                 gpio_mockup_err("error registering platform driver\n");
 379                 return err;
 380         }
 381
 382         for (i = 0; i < num_chips; i++) {
 383                 memset(properties, 0, sizeof(properties));
 384                 memset(&pdevinfo, 0, sizeof(pdevinfo));
 385                 prop = 0;
 386
 387                 base = gpio_mockup_range_base(i);
 388                 if (base >= 0)
 389                         properties[prop++] = PROPERTY_ENTRY_U32("gpio-base",
 390                                                                 base);
 391
 392                 ngpio = base < 0 ? gpio_mockup_range_ngpio(i)
 393                                  : gpio_mockup_range_ngpio(i) - base;
 394                 properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
 395
 396                 if (gpio_mockup_named_lines)
 397                         properties[prop++] = PROPERTY_ENTRY_BOOL(
 398                                                 "named-gpio-lines");
 399
 400                 pdevinfo.name = GPIO_MOCKUP_NAME;
 401                 pdevinfo.id = i;
 402                 pdevinfo.properties = properties;
 403
 404                 pdev = platform_device_register_full(&pdevinfo);
 405                 if (IS_ERR(pdev)) {
 406                         gpio_mockup_err("error registering device");
 407                         platform_driver_unregister(&gpio_mockup_driver);
 408                         gpio_mockup_unregister_pdevs();
 409                         return PTR_ERR(pdev);
 410                 }
 411
 412                 gpio_mockup_pdevs[i] = pdev;
 413         }
 414
 415         return 0;
 416 }
 417
 418 static void __exit gpio_mockup_exit(void)
 419 {
 420         debugfs_remove_recursive(gpio_mockup_dbg_dir);
 421         platform_driver_unregister(&gpio_mockup_driver);
 422         gpio_mockup_unregister_pdevs();
 423 }
 424
 425 module_init(gpio_mockup_init);
 426 module_exit(gpio_mockup_exit);
 427
 428 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
 429 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
 430 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
 431 MODULE_DESCRIPTION("GPIO Testing driver");
 432 MODULE_LICENSE("GPL v2");