drivers/gpio/gpio-mockup.c

   1 /*
   2  * GPIO Testing Device Driver
   3  *
   4  * Copyright (C) 2014  Kamlakant Patel <kamlakant.patel@broadcom.com>
   5  * Copyright (C) 2015-2016  Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>
   6  * Copyright (C) 2017 Bartosz Golaszewski <brgl@bgdev.pl>
   7  *
   8  * This program is free software; you can redistribute  it and/or modify it
   9  * under  the terms of  the GNU General  Public License as published by the
  10  * Free Software Foundation;  either version 2 of the  License, or (at your
  11  * option) any later version.
  12  *
  13  */
  14
  15 #include <linux/init.h>
  16 #include <linux/module.h>
  17 #include <linux/gpio/driver.h>
  18 #include <linux/gpio/consumer.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/slab.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/irq.h>
  23 #include <linux/irq_sim.h>
  24 #include <linux/debugfs.h>
  25 #include <linux/uaccess.h>
  26
  27 #include "gpiolib.h"
  28
  29 #define GPIO_MOCKUP_NAME        "gpio-mockup"
  30 #define GPIO_MOCKUP_MAX_GC      10
  31 /*
  32  * We're storing two values per chip: the GPIO base and the number
  33  * of GPIO lines.
  34  */
  35 #define GPIO_MOCKUP_MAX_RANGES  (GPIO_MOCKUP_MAX_GC * 2)
  36
  37 #define gpio_mockup_err(...)    pr_err(GPIO_MOCKUP_NAME ": " __VA_ARGS__)
  38
  39 enum {
  40         GPIO_MOCKUP_DIR_OUT = 0,
  41         GPIO_MOCKUP_DIR_IN = 1,
  42 };
  43
  44 /*
  45  * struct gpio_pin_status - structure describing a GPIO status
  46  * @dir:       Configures direction of gpio as "in" or "out", 0=in, 1=out
  47  * @value:     Configures status of the gpio as 0(low) or 1(high)
  48  */
  49 struct gpio_mockup_line_status {
  50         int dir;
  51         int value;
  52 };
  53
  54 struct gpio_mockup_chip {
  55         struct gpio_chip gc;
  56         struct gpio_mockup_line_status *lines;
  57         struct irq_sim irqsim;
  58         struct dentry *dbg_dir;
  59 };
  60
  61 struct gpio_mockup_dbgfs_private {
  62         struct gpio_mockup_chip *chip;
  63         struct gpio_desc *desc;
  64         int offset;
  65 };
  66
  67 struct gpio_mockup_platform_data {
  68         int base;
  69         int ngpio;
  70         int index;
  71         bool named_lines;
  72 };
  73
  74 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
  75 static int gpio_mockup_num_ranges;
  76 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
  77
  78 static bool gpio_mockup_named_lines;
  79 module_param_named(gpio_mockup_named_lines,
  80                    gpio_mockup_named_lines, bool, 0400);
  81
  82 static struct dentry *gpio_mockup_dbg_dir;
  83
  84 static int gpio_mockup_range_base(unsigned int index)
  85 {
  86         return gpio_mockup_ranges[index * 2];
  87 }
  88
  89 static int gpio_mockup_range_ngpio(unsigned int index)
  90 {
  91         return gpio_mockup_ranges[index * 2 + 1];
  92 }
  93
  94 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
  95 {
  96         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
  97
  98         return chip->lines[offset].value;
  99 }
 100
 101 static void gpio_mockup_set(struct gpio_chip *gc,
 102                             unsigned int offset, int value)
 103 {
 104         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 105
 106         chip->lines[offset].value = !!value;
 107 }
 108
 109 static void gpio_mockup_set_multiple(struct gpio_chip *gc,
 110                                      unsigned long *mask, unsigned long *bits)
 111 {
 112         unsigned int bit;
 113
 114         for_each_set_bit(bit, mask, gc->ngpio)
 115                 gpio_mockup_set(gc, bit, test_bit(bit, bits));
 116
 117 }
 118
 119 static int gpio_mockup_dirout(struct gpio_chip *gc,
 120                               unsigned int offset, int value)
 121 {
 122         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 123
 124         gpio_mockup_set(gc, offset, value);
 125         chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT;
 126
 127         return 0;
 128 }
 129
 130 static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
 131 {
 132         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 133
 134         chip->lines[offset].dir = GPIO_MOCKUP_DIR_IN;
 135
 136         return 0;
 137 }
 138
 139 static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
 140 {
 141         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 142
 143         return chip->lines[offset].dir;
 144 }
 145
 146 static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
 147 {
 148         struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 149
 150         return irq_sim_irqnum(&chip->irqsim, offset);
 151 }
 152
 153 static ssize_t gpio_mockup_event_write(struct file *file,
 154                                        const char __user *usr_buf,
 155                                        size_t size, loff_t *ppos)
 156 {
 157         struct gpio_mockup_dbgfs_private *priv;
 158         struct gpio_mockup_chip *chip;
 159         struct seq_file *sfile;
 160         struct gpio_desc *desc;
 161         int rv, val;
 162
 163         rv = kstrtoint_from_user(usr_buf, size, 0, &val);
 164         if (rv)
 165                 return rv;
 166         if (val != 0 && val != 1)
 167                 return -EINVAL;
 168
 169         sfile = file->private_data;
 170         priv = sfile->private;
 171         desc = priv->desc;
 172         chip = priv->chip;
 173
 174         gpiod_set_value_cansleep(desc, val);
 175         irq_sim_fire(&chip->irqsim, priv->offset);
 176
 177         return size;
 178 }
 179
 180 static int gpio_mockup_event_open(struct inode *inode, struct file *file)
 181 {
 182         return single_open(file, NULL, inode->i_private);
 183 }
 184
 185 static const struct file_operations gpio_mockup_event_ops = {
 186         .owner = THIS_MODULE,
 187         .open = gpio_mockup_event_open,
 188         .write = gpio_mockup_event_write,
 189         .llseek = no_llseek,
 190 };
 191
 192 static void gpio_mockup_debugfs_setup(struct device *dev,
 193                                       struct gpio_mockup_chip *chip)
 194 {
 195         struct gpio_mockup_dbgfs_private *priv;
 196         struct dentry *evfile, *link;
 197         struct gpio_chip *gc;
 198         const char *devname;
 199         char *name;
 200         int i;
 201
 202         gc = &chip->gc;
 203         devname = dev_name(&gc->gpiodev->dev);
 204
 205         chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
 206         if (IS_ERR_OR_NULL(chip->dbg_dir))
 207                 goto err;
 208
 209         link = debugfs_create_symlink(gc->label, gpio_mockup_dbg_dir, devname);
 210         if (IS_ERR_OR_NULL(link))
 211                 goto err;
 212
 213         for (i = 0; i < gc->ngpio; i++) {
 214                 name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
 215                 if (!name)
 216                         goto err;
 217
 218                 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 219                 if (!priv)
 220                         goto err;
 221
 222                 priv->chip = chip;
 223                 priv->offset = i;
 224                 priv->desc = &gc->gpiodev->descs[i];
 225
 226                 evfile = debugfs_create_file(name, 0200, chip->dbg_dir, priv,
 227                                              &gpio_mockup_event_ops);
 228                 if (IS_ERR_OR_NULL(evfile))
 229                         goto err;
 230         }
 231
 232         return;
 233
 234 err:
 235         dev_err(dev, "error creating debugfs event files\n");
 236 }
 237
 238 static int gpio_mockup_name_lines(struct device *dev,
 239                                   struct gpio_mockup_chip *chip)
 240 {
 241         struct gpio_chip *gc = &chip->gc;
 242         char **names;
 243         int i;
 244
 245         names = devm_kcalloc(dev, gc->ngpio, sizeof(char *), GFP_KERNEL);
 246         if (!names)
 247                 return -ENOMEM;
 248
 249         for (i = 0; i < gc->ngpio; i++) {
 250                 names[i] = devm_kasprintf(dev, GFP_KERNEL,
 251                                           "%s-%d", gc->label, i);
 252                 if (!names[i])
 253                         return -ENOMEM;
 254         }
 255
 256         gc->names = (const char *const *)names;
 257
 258         return 0;
 259 }
 260
 261 static int gpio_mockup_probe(struct platform_device *pdev)
 262 {
 263         struct gpio_mockup_platform_data *pdata;
 264         struct gpio_mockup_chip *chip;
 265         struct gpio_chip *gc;
 266         int rv, base, ngpio;
 267         struct device *dev;
 268         char *name;
 269
 270         dev = &pdev->dev;
 271         pdata = dev_get_platdata(dev);
 272         base = pdata->base;
 273         ngpio = pdata->ngpio;
 274
 275         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 276         if (!chip)
 277                 return -ENOMEM;
 278
 279         name = devm_kasprintf(dev, GFP_KERNEL, "%s-%c",
 280                               pdev->name, pdata->index);
 281         if (!name)
 282                 return -ENOMEM;
 283
 284         gc = &chip->gc;
 285         gc->base = base;
 286         gc->ngpio = ngpio;
 287         gc->label = name;
 288         gc->owner = THIS_MODULE;
 289         gc->parent = dev;
 290         gc->get = gpio_mockup_get;
 291         gc->set = gpio_mockup_set;
 292         gc->set_multiple = gpio_mockup_set_multiple;
 293         gc->direction_output = gpio_mockup_dirout;
 294         gc->direction_input = gpio_mockup_dirin;
 295         gc->get_direction = gpio_mockup_get_direction;
 296         gc->to_irq = gpio_mockup_to_irq;
 297
 298         chip->lines = devm_kcalloc(dev, gc->ngpio,
 299                                    sizeof(*chip->lines), GFP_KERNEL);
 300         if (!chip->lines)
 301                 return -ENOMEM;
 302
 303         if (pdata->named_lines) {
 304                 rv = gpio_mockup_name_lines(dev, chip);
 305                 if (rv)
 306                         return rv;
 307         }
 308
 309         rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio);
 310         if (rv < 0)
 311                 return rv;
 312
 313         rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
 314         if (rv)
 315                 return rv;
 316
 317         if (gpio_mockup_dbg_dir)
 318                 gpio_mockup_debugfs_setup(dev, chip);
 319
 320         return 0;
 321 }
 322
 323 static struct platform_driver gpio_mockup_driver = {
 324         .driver = {
 325                 .name = GPIO_MOCKUP_NAME,
 326         },
 327         .probe = gpio_mockup_probe,
 328 };
 329
 330 static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
 331
 332 static void gpio_mockup_unregister_pdevs(void)
 333 {
 334         struct platform_device *pdev;
 335         int i;
 336
 337         for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
 338                 pdev = gpio_mockup_pdevs[i];
 339
 340                 if (pdev)
 341                         platform_device_unregister(pdev);
 342         }
 343 }
 344
 345 static int __init gpio_mockup_init(void)
 346 {
 347         int i, num_chips, err = 0, index = 'A';
 348         struct gpio_mockup_platform_data pdata;
 349         struct platform_device *pdev;
 350
 351         if ((gpio_mockup_num_ranges < 2) ||
 352             (gpio_mockup_num_ranges % 2) ||
 353             (gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
 354                 return -EINVAL;
 355
 356         /* Each chip is described by two values. */
 357         num_chips = gpio_mockup_num_ranges / 2;
 358
 359         /*
 360          * The second value in the <base GPIO - number of GPIOS> pair must
 361          * always be greater than 0.
 362          */
 363         for (i = 0; i < num_chips; i++) {
 364                 if (gpio_mockup_range_ngpio(i) < 0)
 365                         return -EINVAL;
 366         }
 367
 368         gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup-event", NULL);
 369         if (IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
 370                 gpio_mockup_err("error creating debugfs directory\n");
 371
 372         err = platform_driver_register(&gpio_mockup_driver);
 373         if (err) {
 374                 gpio_mockup_err("error registering platform driver\n");
 375                 return err;
 376         }
 377
 378         for (i = 0; i < num_chips; i++) {
 379                 pdata.index = index++;
 380                 pdata.base = gpio_mockup_range_base(i);
 381                 pdata.ngpio = pdata.base < 0
 382                                 ? gpio_mockup_range_ngpio(i)
 383                                 : gpio_mockup_range_ngpio(i) - pdata.base;
 384                 pdata.named_lines = gpio_mockup_named_lines;
 385
 386                 pdev = platform_device_register_resndata(NULL,
 387                                                          GPIO_MOCKUP_NAME,
 388                                                          i, NULL, 0, &pdata,
 389                                                          sizeof(pdata));
 390                 if (IS_ERR(pdev)) {
 391                         gpio_mockup_err("error registering device");
 392                         platform_driver_unregister(&gpio_mockup_driver);
 393                         gpio_mockup_unregister_pdevs();
 394                         return PTR_ERR(pdev);
 395                 }
 396
 397                 gpio_mockup_pdevs[i] = pdev;
 398         }
 399
 400         return 0;
 401 }
 402
 403 static void __exit gpio_mockup_exit(void)
 404 {
 405         debugfs_remove_recursive(gpio_mockup_dbg_dir);
 406         platform_driver_unregister(&gpio_mockup_driver);
 407         gpio_mockup_unregister_pdevs();
 408 }
 409
 410 module_init(gpio_mockup_init);
 411 module_exit(gpio_mockup_exit);
 412
 413 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
 414 MODULE_AUTHOR("Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>");
 415 MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
 416 MODULE_DESCRIPTION("GPIO Testing driver");
 417 MODULE_LICENSE("GPL v2");