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
  22 #include "gpiolib.h"
  23
  24 #define GPIO_MOCKUP_NAME        "gpio-mockup"
  25 #define GPIO_MOCKUP_MAX_GC      10
  26 /*
  27  * We're storing two values per chip: the GPIO base and the number
  28  * of GPIO lines.
  29  */
  30 #define GPIO_MOCKUP_MAX_RANGES  (GPIO_MOCKUP_MAX_GC * 2)
  31
  32 #define gpio_mockup_err(...)    pr_err(GPIO_MOCKUP_NAME ": " __VA_ARGS__)
  33
  34 enum {
  35         GPIO_MOCKUP_DIR_IN = 0,
  36         GPIO_MOCKUP_DIR_OUT = 1,
  37 };
  38
  39 /*
  40  * struct gpio_pin_status - structure describing a GPIO status
  41  * @dir:       Configures direction of gpio as "in" or "out", 0=in, 1=out
  42  * @value:     Configures status of the gpio as 0(low) or 1(high)
  43  */
  44 struct gpio_mockup_line_status {
  45         int dir;
  46         int value;
  47 };
  48
  49 struct gpio_mockup_chip {
  50         struct gpio_chip gc;
  51         struct gpio_mockup_line_status *lines;
  52         struct irq_sim irqsim;
  53         struct dentry *dbg_dir;
  54 };
  55
  56 struct gpio_mockup_dbgfs_private {
  57         struct gpio_mockup_chip *chip;
  58         struct gpio_desc *desc;
  59         int offset;
  60 };
  61
  62 struct gpio_mockup_platform_data {
  63         int base;
  64         int ngpio;
  65         int index;
  66         bool named_lines;
  67 };
  68
  69 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
  70 static int gpio_mockup_num_ranges;
  71 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
  72
  73 static bool gpio_mockup_named_lines;
  74 module_param_named(gpio_mockup_named_lines,
  75                    gpio_mockup_named_lines, bool, 0400);
  76
  77 static struct dentry *gpio_mockup_dbg_dir;
  78
  79 static int gpio_mockup_range_base(unsigned int index)
  80 {
  81         return gpio_mockup_ranges[index * 2];
  82 }
  83
  84 static int gpio_mockup_range_ngpio(unsigned int index)
  85 {
  86         return gpio_mockup_ranges[index * 2 + 1];
  87 }
  88
  89 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
  90 {
  91         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
  92
  93         return chip->lines[offset].value;
  94 }
  95
  96 static void gpio_mockup_set(struct gpio_chip *gc,
  97                             unsigned int offset, int value)
  98 {
  99         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 100
 101         chip->lines[offset].value = !!value;
 102 }
 103
 104 static void gpio_mockup_set_multiple(struct gpio_chip *gc,
 105                                      unsigned long *mask, unsigned long *bits)
 106 {
 107         unsigned int bit;
 108
 109         for_each_set_bit(bit, mask, gc->ngpio)
 110                 gpio_mockup_set(gc, bit, test_bit(bit, bits));
 111
 112 }
 113
 114 static int gpio_mockup_dirout(struct gpio_chip *gc,
 115                               unsigned int offset, int value)
 116 {
 117         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 118
 119         gpio_mockup_set(gc, offset, value);
 120         chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT;
 121
 122         return 0;
 123 }
 124
 125 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
 126 {
 127         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 128
 129         chip->lines[offset].dir = GPIO_MOCKUP_DIR_IN;
 130
 131         return 0;
 132 }
 133
 134 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
 135 {
 136         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 137
 138         return !chip->lines[offset].dir;
 139 }
 140
 141 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
 142 {
 143         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 144
 145         return irq_sim_irqnum(&chip->irqsim, offset);
 146 }
 147
 148 static ssize_t gpio_mockup_event_write(struct file *file,
 149                                        const char __user *usr_buf,
 150                                        size_t size, loff_t *ppos)
 151 {
 152         struct gpio_mockup_dbgfs_private *priv;
 153         struct gpio_mockup_chip *chip;
 154         struct seq_file *sfile;
 155         struct gpio_desc *desc;
 156         int rv, val;
 157
 158         rv = kstrtoint_from_user(usr_buf, size, 0, &val);
 159         if (rv)
 160                 return rv;
 161         if (val != 0 && val != 1)
 162                 return -EINVAL;
 163
 164         sfile = file->private_data;
 165         priv = sfile->private;
 166         desc = priv->desc;
 167         chip = priv->chip;
 168
 169         gpiod_set_value_cansleep(desc, val);
 170         irq_sim_fire(&chip->irqsim, priv->offset);
 171
 172         return size;
 173 }
 174
 175 static int gpio_mockup_event_open(struct inode *inode, struct file *file)
 176 {
 177         return single_open(file, NULL, inode->i_private);
 178 }
 179
 180 static const struct file_operations gpio_mockup_event_ops = {
 181         .owner = THIS_MODULE,
 182         .open = gpio_mockup_event_open,
 183         .write = gpio_mockup_event_write,
 184         .llseek = no_llseek,
 185 };
 186
 187 static void gpio_mockup_debugfs_setup(struct device *dev,
 188                                       struct gpio_mockup_chip *chip)
 189 {
 190         struct gpio_mockup_dbgfs_private *priv;
 191         struct dentry *evfile, *link;
 192         struct gpio_chip *gc;
 193         const char *devname;
 194         char *name;
 195         int i;
 196
 197         gc = &chip->gc;
 198         devname = dev_name(&gc->gpiodev->dev);
 199
 200         chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
 201         if (IS_ERR_OR_NULL(chip->dbg_dir))
 202                 goto err;
 203
 204         link = debugfs_create_symlink(gc->label, gpio_mockup_dbg_dir, devname);
 205         if (IS_ERR_OR_NULL(link))
 206                 goto err;
 207
 208         for (i = 0; i < gc->ngpio; i++) {
 209                 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
 210                 if (!name)
 211                         goto err;
 212
 213                 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 214                 if (!priv)
 215                         goto err;
 216
 217                 priv->chip = chip;
 218                 priv->offset = i;
 219                 priv->desc = &gc->gpiodev->descs[i];
 220
 221                 evfile = debugfs_create_file(name, 0200, chip->dbg_dir, priv,
 222                                              &gpio_mockup_event_ops);
 223                 if (IS_ERR_OR_NULL(evfile))
 224                         goto err;
 225         }
 226
 227         return;
 228
 229 err:
 230         dev_err(dev, "error creating debugfs event files\n");
 231 }
 232
 233 static int gpio_mockup_name_lines(struct device *dev,
 234                                   struct gpio_mockup_chip *chip)
 235 {
 236         struct gpio_chip *gc = &chip->gc;
 237         char **names;
 238         int i;
 239
 240         names = devm_kcalloc(dev, gc->ngpio, sizeof(char *), GFP_KERNEL);
 241         if (!names)
 242                 return -ENOMEM;
 243
 244         for (i = 0; i < gc->ngpio; i++) {
 245                 names[i] = devm_kasprintf(dev, GFP_KERNEL,
 246                                           "%s-%d", gc->label, i);
 247                 if (!names[i])
 248                         return -ENOMEM;
 249         }
 250
 251         gc->names = (const char *const *)names;
 252
 253         return 0;
 254 }
 255
 256 static int gpio_mockup_probe(struct platform_device *pdev)
 257 {
 258         struct gpio_mockup_platform_data *pdata;
 259         struct gpio_mockup_chip *chip;
 260         struct gpio_chip *gc;
 261         int rv, base, ngpio;
 262         struct device *dev;
 263         char *name;
 264
 265         dev = &pdev->dev;
 266         pdata = dev_get_platdata(dev);
 267         base = pdata->base;
 268         ngpio = pdata->ngpio;
 269
 270         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 271         if (!chip)
 272                 return -ENOMEM;
 273
 274         name = devm_kasprintf(dev, GFP_KERNEL, "%s-%c",
 275                               pdev->name, pdata->index);
 276         if (!name)
 277                 return -ENOMEM;
 278
 279         gc = &chip->gc;
 280         gc->base = base;
 281         gc->ngpio = ngpio;
 282         gc->label = name;
 283         gc->owner = THIS_MODULE;
 284         gc->parent = dev;
 285         gc->get = gpio_mockup_get;
 286         gc->set = gpio_mockup_set;
 287         gc->set_multiple = gpio_mockup_set_multiple;
 288         gc->direction_output = gpio_mockup_dirout;
 289         gc->direction_input = gpio_mockup_dirin;
 290         gc->get_direction = gpio_mockup_get_direction;
 291         gc->to_irq = gpio_mockup_to_irq;
 292
 293         chip->lines = devm_kcalloc(dev, gc->ngpio,
 294                                    sizeof(*chip->lines), GFP_KERNEL);
 295         if (!chip->lines)
 296                 return -ENOMEM;
 297
 298         if (pdata->named_lines) {
 299                 rv = gpio_mockup_name_lines(dev, chip);
 300                 if (rv)
 301                         return rv;
 302         }
 303
 304         rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio);
 305         if (rv < 0)
 306                 return rv;
 307
 308         rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
 309         if (rv)
 310                 return rv;
 311
 312         if (!IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
 313                 gpio_mockup_debugfs_setup(dev, chip);
 314
 315         return 0;
 316 }
 317
 318 static struct platform_driver gpio_mockup_driver = {
 319         .driver = {
 320                 .name = GPIO_MOCKUP_NAME,
 321         },
 322         .probe = gpio_mockup_probe,
 323 };
 324
 325 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
 326
 327 static void gpio_mockup_unregister_pdevs(void)
 328 {
 329         struct platform_device *pdev;
 330         int i;
 331
 332         for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
 333                 pdev = gpio_mockup_pdevs[i];
 334
 335                 if (pdev)
 336                         platform_device_unregister(pdev);
 337         }
 338 }
 339
 340 static int __init gpio_mockup_init(void)
 341 {
 342         int i, num_chips, err = 0, index = 'A';
 343         struct gpio_mockup_platform_data pdata;
 344         struct platform_device *pdev;
 345
 346         if ((gpio_mockup_num_ranges < 2) ||
 347             (gpio_mockup_num_ranges % 2) ||
 348             (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
 349                 return -EINVAL;
 350
 351         /* Each chip is described by two values. */
 352         num_chips = gpio_mockup_num_ranges / 2;
 353
 354         /*
 355          * The second value in the <base GPIO - number of GPIOS> pair must
 356          * always be greater than 0.
 357          */
 358         for (i = 0; i < num_chips; i++) {
 359                 if (gpio_mockup_range_ngpio(i) < 0)
 360                         return -EINVAL;
 361         }
 362
 363         gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup-event", NULL);
 364         if (IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
 365                 gpio_mockup_err("error creating debugfs directory\n");
 366
 367         err = platform_driver_register(&gpio_mockup_driver);
 368         if (err) {
 369                 gpio_mockup_err("error registering platform driver\n");
 370                 return err;
 371         }
 372
 373         for (i = 0; i < num_chips; i++) {
 374                 pdata.index = index++;
 375                 pdata.base = gpio_mockup_range_base(i);
 376                 pdata.ngpio = pdata.base < 0
 377                                 ? gpio_mockup_range_ngpio(i)
 378                                 : gpio_mockup_range_ngpio(i) - pdata.base;
 379                 pdata.named_lines = gpio_mockup_named_lines;
 380
 381                 pdev = platform_device_register_resndata(NULL,
 382                                                          GPIO_MOCKUP_NAME,
 383                                                          i, NULL, 0, &pdata,
 384                                                          sizeof(pdata));
 385                 if (IS_ERR(pdev)) {
 386                         gpio_mockup_err("error registering device");
 387                         platform_driver_unregister(&gpio_mockup_driver);
 388                         gpio_mockup_unregister_pdevs();
 389                         return PTR_ERR(pdev);
 390                 }
 391
 392                 gpio_mockup_pdevs[i] = pdev;
 393         }
 394
 395         return 0;
 396 }
 397
 398 static void __exit gpio_mockup_exit(void)
 399 {
 400         debugfs_remove_recursive(gpio_mockup_dbg_dir);
 401         platform_driver_unregister(&gpio_mockup_driver);
 402         gpio_mockup_unregister_pdevs();
 403 }
 404
 405 module_init(gpio_mockup_init);
 406 module_exit(gpio_mockup_exit);
 407
 408 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
 409 MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
 410 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
 411 MODULE_DESCRIPTION("GPIO Testing driver");
 412 MODULE_LICENSE("GPL v2");