drivers/watchdog/ts72xx_wdt.c

   1 /*
   2  * Watchdog driver for Technologic Systems TS-72xx based SBCs
   3  * (TS-7200, TS-7250 and TS-7260). These boards have external
   4  * glue logic CPLD chip, which includes programmable watchdog
   5  * timer.
   6  *
   7  * Copyright (c) 2009 Mika Westerberg <mika.westerberg@iki.fi>
   8  *
   9  * This driver is based on ep93xx_wdt and wm831x_wdt drivers.
  10  *
  11  * This file is licensed under the terms of the GNU General Public
  12  * License version 2. This program is licensed "as is" without any
  13  * warranty of any kind, whether express or implied.
  14  */
  15
  16 #include <linux/fs.h>
  17 #include <linux/io.h>
  18 #include <linux/module.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/mutex.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/slab.h>
  24 #include <linux/watchdog.h>
  25 #include <linux/uaccess.h>
  26
  27 #define TS72XX_WDT_FEED_VAL             0x05
  28 #define TS72XX_WDT_DEFAULT_TIMEOUT      8
  29
  30 static int timeout = TS72XX_WDT_DEFAULT_TIMEOUT;
  31 module_param(timeout, int, 0);
  32 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. "
  33                           "(1 <= timeout <= 8, default="
  34                           __MODULE_STRING(TS72XX_WDT_DEFAULT_TIMEOUT)
  35                           ")");
  36
  37 static bool nowayout = WATCHDOG_NOWAYOUT;
  38 module_param(nowayout, bool, 0);
  39 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  40
  41 /**
  42  * struct ts72xx_wdt - watchdog control structure
  43  * @lock: lock that protects this structure
  44  * @regval: watchdog timeout value suitable for control register
  45  * @flags: flags controlling watchdog device state
  46  * @control_reg: watchdog control register
  47  * @feed_reg: watchdog feed register
  48  * @pdev: back pointer to platform dev
  49  */
  50 struct ts72xx_wdt {
  51         struct mutex    lock;
  52         int             regval;
  53
  54 #define TS72XX_WDT_BUSY_FLAG            1
  55 #define TS72XX_WDT_EXPECT_CLOSE_FLAG    2
  56         int             flags;
  57
  58         void __iomem    *control_reg;
  59         void __iomem    *feed_reg;
  60
  61         struct platform_device *pdev;
  62 };
  63
  64 static struct platform_device *ts72xx_wdt_pdev;
  65
  66 /*
  67  * TS-72xx Watchdog supports following timeouts (value written
  68  * to control register):
  69  *      value   description
  70  *      -------------------------
  71  *      0x00    watchdog disabled
  72  *      0x01    250ms
  73  *      0x02    500ms
  74  *      0x03    1s
  75  *      0x04    reserved
  76  *      0x05    2s
  77  *      0x06    4s
  78  *      0x07    8s
  79  *
  80  * Timeouts below 1s are not very usable so we don't
  81  * allow them at all.
  82  *
  83  * We provide two functions that convert between these:
  84  * timeout_to_regval() and regval_to_timeout().
  85  */
  86 static const struct {
  87         int     timeout;
  88         int     regval;
  89 } ts72xx_wdt_map[] = {
  90         { 1, 3 },
  91         { 2, 5 },
  92         { 4, 6 },
  93         { 8, 7 },
  94 };
  95
  96 /**
  97  * timeout_to_regval() - converts given timeout to control register value
  98  * @new_timeout: timeout in seconds to be converted
  99  *
 100  * Function converts given @new_timeout into valid value that can
 101  * be programmed into watchdog control register. When conversion is
 102  * not possible, function returns %-EINVAL.
 103  */
 104 static int timeout_to_regval(int new_timeout)
 105 {
 106         int i;
 107
 108         /* first limit it to 1 - 8 seconds */
 109         new_timeout = clamp_val(new_timeout, 1, 8);
 110
 111         for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
 112                 if (ts72xx_wdt_map[i].timeout >= new_timeout)
 113                         return ts72xx_wdt_map[i].regval;
 114         }
 115
 116         return -EINVAL;
 117 }
 118
 119 /**
 120  * regval_to_timeout() - converts control register value to timeout
 121  * @regval: control register value to be converted
 122  *
 123  * Function converts given @regval to timeout in seconds (1, 2, 4 or 8).
 124  * If @regval cannot be converted, function returns %-EINVAL.
 125  */
 126 static int regval_to_timeout(int regval)
 127 {
 128         int i;
 129
 130         for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
 131                 if (ts72xx_wdt_map[i].regval == regval)
 132                         return ts72xx_wdt_map[i].timeout;
 133         }
 134
 135         return -EINVAL;
 136 }
 137
 138 /**
 139  * ts72xx_wdt_kick() - kick the watchdog
 140  * @wdt: watchdog to be kicked
 141  *
 142  * Called with @wdt->lock held.
 143  */
 144 static inline void ts72xx_wdt_kick(struct ts72xx_wdt *wdt)
 145 {
 146         __raw_writeb(TS72XX_WDT_FEED_VAL, wdt->feed_reg);
 147 }
 148
 149 /**
 150  * ts72xx_wdt_start() - starts the watchdog timer
 151  * @wdt: watchdog to be started
 152  *
 153  * This function programs timeout to watchdog timer
 154  * and starts it.
 155  *
 156  * Called with @wdt->lock held.
 157  */
 158 static void ts72xx_wdt_start(struct ts72xx_wdt *wdt)
 159 {
 160         /*
 161          * To program the wdt, it first must be "fed" and
 162          * only after that (within 30 usecs) the configuration
 163          * can be changed.
 164          */
 165         ts72xx_wdt_kick(wdt);
 166         __raw_writeb((u8)wdt->regval, wdt->control_reg);
 167 }
 168
 169 /**
 170  * ts72xx_wdt_stop() - stops the watchdog timer
 171  * @wdt: watchdog to be stopped
 172  *
 173  * Called with @wdt->lock held.
 174  */
 175 static void ts72xx_wdt_stop(struct ts72xx_wdt *wdt)
 176 {
 177         ts72xx_wdt_kick(wdt);
 178         __raw_writeb(0, wdt->control_reg);
 179 }
 180
 181 static int ts72xx_wdt_open(struct inode *inode, struct file *file)
 182 {
 183         struct ts72xx_wdt *wdt = platform_get_drvdata(ts72xx_wdt_pdev);
 184         int regval;
 185
 186         /*
 187          * Try to convert default timeout to valid register
 188          * value first.
 189          */
 190         regval = timeout_to_regval(timeout);
 191         if (regval < 0) {
 192                 dev_err(&wdt->pdev->dev,
 193                         "failed to convert timeout (%d) to register value\n",
 194                         timeout);
 195                 return regval;
 196         }
 197
 198         if (mutex_lock_interruptible(&wdt->lock))
 199                 return -ERESTARTSYS;
 200
 201         if ((wdt->flags & TS72XX_WDT_BUSY_FLAG) != 0) {
 202                 mutex_unlock(&wdt->lock);
 203                 return -EBUSY;
 204         }
 205
 206         wdt->flags = TS72XX_WDT_BUSY_FLAG;
 207         wdt->regval = regval;
 208         file->private_data = wdt;
 209
 210         ts72xx_wdt_start(wdt);
 211
 212         mutex_unlock(&wdt->lock);
 213         return nonseekable_open(inode, file);
 214 }
 215
 216 static int ts72xx_wdt_release(struct inode *inode, struct file *file)
 217 {
 218         struct ts72xx_wdt *wdt = file->private_data;
 219
 220         if (mutex_lock_interruptible(&wdt->lock))
 221                 return -ERESTARTSYS;
 222
 223         if ((wdt->flags & TS72XX_WDT_EXPECT_CLOSE_FLAG) != 0) {
 224                 ts72xx_wdt_stop(wdt);
 225         } else {
 226                 dev_warn(&wdt->pdev->dev,
 227                          "TS-72XX WDT device closed unexpectly. "
 228                          "Watchdog timer will not stop!\n");
 229                 /*
 230                  * Kick it one more time, to give userland some time
 231                  * to recover (for example, respawning the kicker
 232                  * daemon).
 233                  */
 234                 ts72xx_wdt_kick(wdt);
 235         }
 236
 237         wdt->flags = 0;
 238
 239         mutex_unlock(&wdt->lock);
 240         return 0;
 241 }
 242
 243 static ssize_t ts72xx_wdt_write(struct file *file,
 244                                 const char __user *data,
 245                                 size_t len,
 246                                 loff_t *ppos)
 247 {
 248         struct ts72xx_wdt *wdt = file->private_data;
 249
 250         if (!len)
 251                 return 0;
 252
 253         if (mutex_lock_interruptible(&wdt->lock))
 254                 return -ERESTARTSYS;
 255
 256         ts72xx_wdt_kick(wdt);
 257
 258         /*
 259          * Support for magic character closing. User process
 260          * writes 'V' into the device, just before it is closed.
 261          * This means that we know that the wdt timer can be
 262          * stopped after user closes the device.
 263          */
 264         if (!nowayout) {
 265                 int i;
 266
 267                 for (i = 0; i < len; i++) {
 268                         char c;
 269
 270                         /* In case it was set long ago */
 271                         wdt->flags &= ~TS72XX_WDT_EXPECT_CLOSE_FLAG;
 272
 273                         if (get_user(c, data + i)) {
 274                                 mutex_unlock(&wdt->lock);
 275                                 return -EFAULT;
 276                         }
 277                         if (c == 'V') {
 278                                 wdt->flags |= TS72XX_WDT_EXPECT_CLOSE_FLAG;
 279                                 break;
 280                         }
 281                 }
 282         }
 283
 284         mutex_unlock(&wdt->lock);
 285         return len;
 286 }
 287
 288 static const struct watchdog_info winfo = {
 289         .options                = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 290                                   WDIOF_MAGICCLOSE,
 291         .firmware_version       = 1,
 292         .identity               = "TS-72XX WDT",
 293 };
 294
 295 static long ts72xx_wdt_ioctl(struct file *file, unsigned int cmd,
 296                              unsigned long arg)
 297 {
 298         struct ts72xx_wdt *wdt = file->private_data;
 299         void __user *argp = (void __user *)arg;
 300         int __user *p = (int __user *)argp;
 301         int error = 0;
 302
 303         if (mutex_lock_interruptible(&wdt->lock))
 304                 return -ERESTARTSYS;
 305
 306         switch (cmd) {
 307         case WDIOC_GETSUPPORT:
 308                 if (copy_to_user(argp, &winfo, sizeof(winfo)))
 309                         error = -EFAULT;
 310                 break;
 311
 312         case WDIOC_GETSTATUS:
 313         case WDIOC_GETBOOTSTATUS:
 314                 error = put_user(0, p);
 315                 break;
 316
 317         case WDIOC_KEEPALIVE:
 318                 ts72xx_wdt_kick(wdt);
 319                 break;
 320
 321         case WDIOC_SETOPTIONS: {
 322                 int options;
 323
 324                 error = get_user(options, p);
 325                 if (error)
 326                         break;
 327
 328                 error = -EINVAL;
 329
 330                 if ((options & WDIOS_DISABLECARD) != 0) {
 331                         ts72xx_wdt_stop(wdt);
 332                         error = 0;
 333                 }
 334                 if ((options & WDIOS_ENABLECARD) != 0) {
 335                         ts72xx_wdt_start(wdt);
 336                         error = 0;
 337                 }
 338
 339                 break;
 340         }
 341
 342         case WDIOC_SETTIMEOUT: {
 343                 int new_timeout;
 344                 int regval;
 345
 346                 error = get_user(new_timeout, p);
 347                 if (error)
 348                         break;
 349
 350                 regval = timeout_to_regval(new_timeout);
 351                 if (regval < 0) {
 352                         error = regval;
 353                         break;
 354                 }
 355                 ts72xx_wdt_stop(wdt);
 356                 wdt->regval = regval;
 357                 ts72xx_wdt_start(wdt);
 358
 359                 /*FALLTHROUGH*/
 360         }
 361
 362         case WDIOC_GETTIMEOUT:
 363                 error = put_user(regval_to_timeout(wdt->regval), p);
 364                 break;
 365
 366         default:
 367                 error = -ENOTTY;
 368                 break;
 369         }
 370
 371         mutex_unlock(&wdt->lock);
 372         return error;
 373 }
 374
 375 static const struct file_operations ts72xx_wdt_fops = {
 376         .owner          = THIS_MODULE,
 377         .llseek         = no_llseek,
 378         .open           = ts72xx_wdt_open,
 379         .release        = ts72xx_wdt_release,
 380         .write          = ts72xx_wdt_write,
 381         .unlocked_ioctl = ts72xx_wdt_ioctl,
 382 };
 383
 384 static struct miscdevice ts72xx_wdt_miscdev = {
 385         .minor          = WATCHDOG_MINOR,
 386         .name           = "watchdog",
 387         .fops           = &ts72xx_wdt_fops,
 388 };
 389
 390 static int ts72xx_wdt_probe(struct platform_device *pdev)
 391 {
 392         struct ts72xx_wdt *wdt;
 393         struct resource *r1, *r2;
 394         int error = 0;
 395
 396         wdt = devm_kzalloc(&pdev->dev, sizeof(struct ts72xx_wdt), GFP_KERNEL);
 397         if (!wdt)
 398                 return -ENOMEM;
 399
 400         r1 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 401         wdt->control_reg = devm_ioremap_resource(&pdev->dev, r1);
 402         if (IS_ERR(wdt->control_reg))
 403                 return PTR_ERR(wdt->control_reg);
 404
 405         r2 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 406         wdt->feed_reg = devm_ioremap_resource(&pdev->dev, r2);
 407         if (IS_ERR(wdt->feed_reg))
 408                 return PTR_ERR(wdt->feed_reg);
 409
 410         platform_set_drvdata(pdev, wdt);
 411         ts72xx_wdt_pdev = pdev;
 412         wdt->pdev = pdev;
 413         mutex_init(&wdt->lock);
 414
 415         /* make sure that the watchdog is disabled */
 416         ts72xx_wdt_stop(wdt);
 417
 418         error = misc_register(&ts72xx_wdt_miscdev);
 419         if (error) {
 420                 dev_err(&pdev->dev, "failed to register miscdev\n");
 421                 return error;
 422         }
 423
 424         dev_info(&pdev->dev, "TS-72xx Watchdog driver\n");
 425
 426         return 0;
 427 }
 428
 429 static int ts72xx_wdt_remove(struct platform_device *pdev)
 430 {
 431         int error;
 432
 433         error = misc_deregister(&ts72xx_wdt_miscdev);
 434
 435         return error;
 436 }
 437
 438 static struct platform_driver ts72xx_wdt_driver = {
 439         .probe          = ts72xx_wdt_probe,
 440         .remove         = ts72xx_wdt_remove,
 441         .driver         = {
 442                 .name   = "ts72xx-wdt",
 443                 .owner  = THIS_MODULE,
 444         },
 445 };
 446
 447 module_platform_driver(ts72xx_wdt_driver);
 448
 449 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>");
 450 MODULE_DESCRIPTION("TS-72xx SBC Watchdog");
 451 MODULE_LICENSE("GPL");
 452 MODULE_ALIAS("platform:ts72xx-wdt");