drivers/watchdog/wm831x_wdt.c

   1 /*
   2  * Watchdog driver for the wm831x PMICs
   3  *
   4  * Copyright (C) 2009 Wolfson Microelectronics
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/moduleparam.h>
  13 #include <linux/types.h>
  14 #include <linux/kernel.h>
  15 #include <linux/fs.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/watchdog.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/gpio.h>
  21
  22 #include <linux/mfd/wm831x/core.h>
  23 #include <linux/mfd/wm831x/pdata.h>
  24 #include <linux/mfd/wm831x/watchdog.h>
  25
  26 static int nowayout = WATCHDOG_NOWAYOUT;
  27 module_param(nowayout, int, 0);
  28 MODULE_PARM_DESC(nowayout,
  29                  "Watchdog cannot be stopped once started (default="
  30                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  31
  32 static unsigned long wm831x_wdt_users;
  33 static struct miscdevice wm831x_wdt_miscdev;
  34 static int wm831x_wdt_expect_close;
  35 static DEFINE_MUTEX(wdt_mutex);
  36 static struct wm831x *wm831x;
  37 static unsigned int update_gpio;
  38 static unsigned int update_state;
  39
  40 /* We can't use the sub-second values here but they're included
  41  * for completeness.  */
  42 static struct {
  43         int time;  /* Seconds */
  44         u16 val;   /* WDOG_TO value */
  45 } wm831x_wdt_cfgs[] = {
  46         {  1, 2 },
  47         {  2, 3 },
  48         {  4, 4 },
  49         {  8, 5 },
  50         { 16, 6 },
  51         { 32, 7 },
  52         { 33, 7 },  /* Actually 32.768s so include both, others round down */
  53 };
  54
  55 static int wm831x_wdt_set_timeout(struct wm831x *wm831x, u16 value)
  56 {
  57         int ret;
  58
  59         mutex_lock(&wdt_mutex);
  60
  61         ret = wm831x_reg_unlock(wm831x);
  62         if (ret == 0) {
  63                 ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
  64                                       WM831X_WDOG_TO_MASK, value);
  65                 wm831x_reg_lock(wm831x);
  66         } else {
  67                 dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
  68                         ret);
  69         }
  70
  71         mutex_unlock(&wdt_mutex);
  72
  73         return ret;
  74 }
  75
  76 static int wm831x_wdt_start(struct wm831x *wm831x)
  77 {
  78         int ret;
  79
  80         mutex_lock(&wdt_mutex);
  81
  82         ret = wm831x_reg_unlock(wm831x);
  83         if (ret == 0) {
  84                 ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
  85                                       WM831X_WDOG_ENA, WM831X_WDOG_ENA);
  86                 wm831x_reg_lock(wm831x);
  87         } else {
  88                 dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
  89                         ret);
  90         }
  91
  92         mutex_unlock(&wdt_mutex);
  93
  94         return ret;
  95 }
  96
  97 static int wm831x_wdt_stop(struct wm831x *wm831x)
  98 {
  99         int ret;
 100
 101         mutex_lock(&wdt_mutex);
 102
 103         ret = wm831x_reg_unlock(wm831x);
 104         if (ret == 0) {
 105                 ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
 106                                       WM831X_WDOG_ENA, 0);
 107                 wm831x_reg_lock(wm831x);
 108         } else {
 109                 dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
 110                         ret);
 111         }
 112
 113         mutex_unlock(&wdt_mutex);
 114
 115         return ret;
 116 }
 117
 118 static int wm831x_wdt_kick(struct wm831x *wm831x)
 119 {
 120         int ret;
 121         u16 reg;
 122
 123         mutex_lock(&wdt_mutex);
 124
 125         if (update_gpio) {
 126                 gpio_set_value_cansleep(update_gpio, update_state);
 127                 update_state = !update_state;
 128                 ret = 0;
 129                 goto out;
 130         }
 131
 132
 133         reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
 134
 135         if (!(reg & WM831X_WDOG_RST_SRC)) {
 136                 dev_err(wm831x->dev, "Hardware watchdog update unsupported\n");
 137                 ret = -EINVAL;
 138                 goto out;
 139         }
 140
 141         reg |= WM831X_WDOG_RESET;
 142
 143         ret = wm831x_reg_unlock(wm831x);
 144         if (ret == 0) {
 145                 ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
 146                 wm831x_reg_lock(wm831x);
 147         } else {
 148                 dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
 149                         ret);
 150         }
 151
 152 out:
 153         mutex_unlock(&wdt_mutex);
 154
 155         return ret;
 156 }
 157
 158 static int wm831x_wdt_open(struct inode *inode, struct file *file)
 159 {
 160         int ret;
 161
 162         if (!wm831x)
 163                 return -ENODEV;
 164
 165         if (test_and_set_bit(0, &wm831x_wdt_users))
 166                 return -EBUSY;
 167
 168         ret = wm831x_wdt_start(wm831x);
 169         if (ret != 0)
 170                 return ret;
 171
 172         return nonseekable_open(inode, file);
 173 }
 174
 175 static int wm831x_wdt_release(struct inode *inode, struct file *file)
 176 {
 177         if (wm831x_wdt_expect_close)
 178                 wm831x_wdt_stop(wm831x);
 179         else {
 180                 dev_warn(wm831x->dev, "Watchdog device closed uncleanly\n");
 181                 wm831x_wdt_kick(wm831x);
 182         }
 183
 184         clear_bit(0, &wm831x_wdt_users);
 185
 186         return 0;
 187 }
 188
 189 static ssize_t wm831x_wdt_write(struct file *file,
 190                                 const char __user *data, size_t count,
 191                                 loff_t *ppos)
 192 {
 193         size_t i;
 194
 195         if (count) {
 196                 wm831x_wdt_kick(wm831x);
 197
 198                 if (!nowayout) {
 199                         /* In case it was set long ago */
 200                         wm831x_wdt_expect_close = 0;
 201
 202                         /* scan to see whether or not we got the magic
 203                            character */
 204                         for (i = 0; i != count; i++) {
 205                                 char c;
 206                                 if (get_user(c, data + i))
 207                                         return -EFAULT;
 208                                 if (c == 'V')
 209                                         wm831x_wdt_expect_close = 42;
 210                         }
 211                 }
 212         }
 213         return count;
 214 }
 215
 216 static const struct watchdog_info ident = {
 217         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 218         .identity = "WM831x Watchdog",
 219 };
 220
 221 static long wm831x_wdt_ioctl(struct file *file, unsigned int cmd,
 222                              unsigned long arg)
 223 {
 224         int ret = -ENOTTY, time, i;
 225         void __user *argp = (void __user *)arg;
 226         int __user *p = argp;
 227         u16 reg;
 228
 229         switch (cmd) {
 230         case WDIOC_GETSUPPORT:
 231                 ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 232                 break;
 233
 234         case WDIOC_GETSTATUS:
 235         case WDIOC_GETBOOTSTATUS:
 236                 ret = put_user(0, p);
 237                 break;
 238
 239         case WDIOC_SETOPTIONS:
 240         {
 241                 int options;
 242
 243                 if (get_user(options, p))
 244                         return -EFAULT;
 245
 246                 ret = -EINVAL;
 247
 248                 /* Setting both simultaneously means at least one must fail */
 249                 if (options == WDIOS_DISABLECARD)
 250                         ret = wm831x_wdt_start(wm831x);
 251
 252                 if (options == WDIOS_ENABLECARD)
 253                         ret = wm831x_wdt_stop(wm831x);
 254                 break;
 255         }
 256
 257         case WDIOC_KEEPALIVE:
 258                 ret = wm831x_wdt_kick(wm831x);
 259                 break;
 260
 261         case WDIOC_SETTIMEOUT:
 262                 ret = get_user(time, p);
 263                 if (ret)
 264                         break;
 265
 266                 if (time == 0) {
 267                         if (nowayout)
 268                                 ret = -EINVAL;
 269                         else
 270                                 wm831x_wdt_stop(wm831x);
 271                         break;
 272                 }
 273
 274                 for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
 275                         if (wm831x_wdt_cfgs[i].time == time)
 276                                 break;
 277                 if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
 278                         ret = -EINVAL;
 279                 else
 280                         ret = wm831x_wdt_set_timeout(wm831x,
 281                                                      wm831x_wdt_cfgs[i].val);
 282                 break;
 283
 284         case WDIOC_GETTIMEOUT:
 285                 reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
 286                 reg &= WM831X_WDOG_TO_MASK;
 287                 for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
 288                         if (wm831x_wdt_cfgs[i].val == reg)
 289                                 break;
 290                 if (i == ARRAY_SIZE(wm831x_wdt_cfgs)) {
 291                         dev_warn(wm831x->dev,
 292                                  "Unknown watchdog configuration: %x\n", reg);
 293                         ret = -EINVAL;
 294                 } else
 295                         ret = put_user(wm831x_wdt_cfgs[i].time, p);
 296
 297         }
 298
 299         return ret;
 300 }
 301
 302 static const struct file_operations wm831x_wdt_fops = {
 303         .owner = THIS_MODULE,
 304         .llseek = no_llseek,
 305         .write = wm831x_wdt_write,
 306         .unlocked_ioctl = wm831x_wdt_ioctl,
 307         .open = wm831x_wdt_open,
 308         .release = wm831x_wdt_release,
 309 };
 310
 311 static struct miscdevice wm831x_wdt_miscdev = {
 312         .minor = WATCHDOG_MINOR,
 313         .name = "watchdog",
 314         .fops = &wm831x_wdt_fops,
 315 };
 316
 317 static int __devinit wm831x_wdt_probe(struct platform_device *pdev)
 318 {
 319         struct wm831x_pdata *chip_pdata;
 320         struct wm831x_watchdog_pdata *pdata;
 321         int reg, ret;
 322
 323         wm831x = dev_get_drvdata(pdev->dev.parent);
 324
 325         ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
 326         if (ret < 0) {
 327                 dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
 328                         ret);
 329                 goto err;
 330         }
 331         reg = ret;
 332
 333         if (reg & WM831X_WDOG_DEBUG)
 334                 dev_warn(wm831x->dev, "Watchdog is paused\n");
 335
 336         /* Apply any configuration */
 337         if (pdev->dev.parent->platform_data) {
 338                 chip_pdata = pdev->dev.parent->platform_data;
 339                 pdata = chip_pdata->watchdog;
 340         } else {
 341                 pdata = NULL;
 342         }
 343
 344         if (pdata) {
 345                 reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK |
 346                          WM831X_WDOG_RST_SRC);
 347
 348                 reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
 349                 reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
 350                 reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;
 351
 352                 if (pdata->update_gpio) {
 353                         ret = gpio_request(pdata->update_gpio,
 354                                            "Watchdog update");
 355                         if (ret < 0) {
 356                                 dev_err(wm831x->dev,
 357                                         "Failed to request update GPIO: %d\n",
 358                                         ret);
 359                                 goto err;
 360                         }
 361
 362                         ret = gpio_direction_output(pdata->update_gpio, 0);
 363                         if (ret != 0) {
 364                                 dev_err(wm831x->dev,
 365                                         "gpio_direction_output returned: %d\n",
 366                                         ret);
 367                                 goto err_gpio;
 368                         }
 369
 370                         update_gpio = pdata->update_gpio;
 371
 372                         /* Make sure the watchdog takes hardware updates */
 373                         reg |= WM831X_WDOG_RST_SRC;
 374                 }
 375
 376                 ret = wm831x_reg_unlock(wm831x);
 377                 if (ret == 0) {
 378                         ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
 379                         wm831x_reg_lock(wm831x);
 380                 } else {
 381                         dev_err(wm831x->dev,
 382                                 "Failed to unlock security key: %d\n", ret);
 383                         goto err_gpio;
 384                 }
 385         }
 386
 387         wm831x_wdt_miscdev.parent = &pdev->dev;
 388
 389         ret = misc_register(&wm831x_wdt_miscdev);
 390         if (ret != 0) {
 391                 dev_err(wm831x->dev, "Failed to register miscdev: %d\n", ret);
 392                 goto err_gpio;
 393         }
 394
 395         return 0;
 396
 397 err_gpio:
 398         if (update_gpio) {
 399                 gpio_free(update_gpio);
 400                 update_gpio = 0;
 401         }
 402 err:
 403         return ret;
 404 }
 405
 406 static int __devexit wm831x_wdt_remove(struct platform_device *pdev)
 407 {
 408         if (update_gpio) {
 409                 gpio_free(update_gpio);
 410                 update_gpio = 0;
 411         }
 412
 413         misc_deregister(&wm831x_wdt_miscdev);
 414
 415         return 0;
 416 }
 417
 418 static struct platform_driver wm831x_wdt_driver = {
 419         .probe = wm831x_wdt_probe,
 420         .remove = __devexit_p(wm831x_wdt_remove),
 421         .driver = {
 422                 .name = "wm831x-watchdog",
 423         },
 424 };
 425
 426 static int __init wm831x_wdt_init(void)
 427 {
 428         return platform_driver_register(&wm831x_wdt_driver);
 429 }
 430 module_init(wm831x_wdt_init);
 431
 432 static void __exit wm831x_wdt_exit(void)
 433 {
 434         platform_driver_unregister(&wm831x_wdt_driver);
 435 }
 436 module_exit(wm831x_wdt_exit);
 437
 438 MODULE_AUTHOR("Mark Brown");
 439 MODULE_DESCRIPTION("WM831x Watchdog");
 440 MODULE_LICENSE("GPL");
 441 MODULE_ALIAS("platform:wm831x-watchdog");