linux/drivers/watchdog/mpcore_wdt.c
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   1/*
   2 *      Watchdog driver for the mpcore watchdog timer
   3 *
   4 *      (c) Copyright 2004 ARM Limited
   5 *
   6 *      Based on the SoftDog driver:
   7 *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
   8 *                                              All Rights Reserved.
   9 *
  10 *      This program is free software; you can redistribute it and/or
  11 *      modify it under the terms of the GNU General Public License
  12 *      as published by the Free Software Foundation; either version
  13 *      2 of the License, or (at your option) any later version.
  14 *
  15 *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  16 *      warranty for any of this software. This material is provided
  17 *      "AS-IS" and at no charge.
  18 *
  19 *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  20 *
  21 */
  22
  23#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  24
  25#include <linux/module.h>
  26#include <linux/moduleparam.h>
  27#include <linux/types.h>
  28#include <linux/miscdevice.h>
  29#include <linux/watchdog.h>
  30#include <linux/fs.h>
  31#include <linux/reboot.h>
  32#include <linux/init.h>
  33#include <linux/interrupt.h>
  34#include <linux/platform_device.h>
  35#include <linux/uaccess.h>
  36#include <linux/slab.h>
  37#include <linux/io.h>
  38
  39#include <asm/smp_twd.h>
  40
  41struct mpcore_wdt {
  42        unsigned long   timer_alive;
  43        struct device   *dev;
  44        void __iomem    *base;
  45        int             irq;
  46        unsigned int    perturb;
  47        char            expect_close;
  48};
  49
  50static struct platform_device *mpcore_wdt_pdev;
  51static DEFINE_SPINLOCK(wdt_lock);
  52
  53#define TIMER_MARGIN    60
  54static int mpcore_margin = TIMER_MARGIN;
  55module_param(mpcore_margin, int, 0);
  56MODULE_PARM_DESC(mpcore_margin,
  57        "MPcore timer margin in seconds. (0 < mpcore_margin < 65536, default="
  58                                __MODULE_STRING(TIMER_MARGIN) ")");
  59
  60static bool nowayout = WATCHDOG_NOWAYOUT;
  61module_param(nowayout, bool, 0);
  62MODULE_PARM_DESC(nowayout,
  63        "Watchdog cannot be stopped once started (default="
  64                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  65
  66#define ONLY_TESTING    0
  67static int mpcore_noboot = ONLY_TESTING;
  68module_param(mpcore_noboot, int, 0);
  69MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, "
  70        "set to 1 to ignore reboots, 0 to reboot (default="
  71                                        __MODULE_STRING(ONLY_TESTING) ")");
  72
  73/*
  74 *      This is the interrupt handler.  Note that we only use this
  75 *      in testing mode, so don't actually do a reboot here.
  76 */
  77static irqreturn_t mpcore_wdt_fire(int irq, void *arg)
  78{
  79        struct mpcore_wdt *wdt = arg;
  80
  81        /* Check it really was our interrupt */
  82        if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
  83                dev_crit(wdt->dev, "Triggered - Reboot ignored\n");
  84                /* Clear the interrupt on the watchdog */
  85                writel(1, wdt->base + TWD_WDOG_INTSTAT);
  86                return IRQ_HANDLED;
  87        }
  88        return IRQ_NONE;
  89}
  90
  91/*
  92 *      mpcore_wdt_keepalive - reload the timer
  93 *
  94 *      Note that the spec says a DIFFERENT value must be written to the reload
  95 *      register each time.  The "perturb" variable deals with this by adding 1
  96 *      to the count every other time the function is called.
  97 */
  98static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
  99{
 100        unsigned long count;
 101
 102        spin_lock(&wdt_lock);
 103        /* Assume prescale is set to 256 */
 104        count =  __raw_readl(wdt->base + TWD_WDOG_COUNTER);
 105        count = (0xFFFFFFFFU - count) * (HZ / 5);
 106        count = (count / 256) * mpcore_margin;
 107
 108        /* Reload the counter */
 109        writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
 110        wdt->perturb = wdt->perturb ? 0 : 1;
 111        spin_unlock(&wdt_lock);
 112}
 113
 114static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
 115{
 116        spin_lock(&wdt_lock);
 117        writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
 118        writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
 119        writel(0x0, wdt->base + TWD_WDOG_CONTROL);
 120        spin_unlock(&wdt_lock);
 121}
 122
 123static void mpcore_wdt_start(struct mpcore_wdt *wdt)
 124{
 125        dev_info(wdt->dev, "enabling watchdog\n");
 126
 127        /* This loads the count register but does NOT start the count yet */
 128        mpcore_wdt_keepalive(wdt);
 129
 130        if (mpcore_noboot) {
 131                /* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
 132                writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
 133        } else {
 134                /* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
 135                writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
 136        }
 137}
 138
 139static int mpcore_wdt_set_heartbeat(int t)
 140{
 141        if (t < 0x0001 || t > 0xFFFF)
 142                return -EINVAL;
 143
 144        mpcore_margin = t;
 145        return 0;
 146}
 147
 148/*
 149 *      /dev/watchdog handling
 150 */
 151static int mpcore_wdt_open(struct inode *inode, struct file *file)
 152{
 153        struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_pdev);
 154
 155        if (test_and_set_bit(0, &wdt->timer_alive))
 156                return -EBUSY;
 157
 158        if (nowayout)
 159                __module_get(THIS_MODULE);
 160
 161        file->private_data = wdt;
 162
 163        /*
 164         *      Activate timer
 165         */
 166        mpcore_wdt_start(wdt);
 167
 168        return nonseekable_open(inode, file);
 169}
 170
 171static int mpcore_wdt_release(struct inode *inode, struct file *file)
 172{
 173        struct mpcore_wdt *wdt = file->private_data;
 174
 175        /*
 176         *      Shut off the timer.
 177         *      Lock it in if it's a module and we set nowayout
 178         */
 179        if (wdt->expect_close == 42)
 180                mpcore_wdt_stop(wdt);
 181        else {
 182                dev_crit(wdt->dev,
 183                         "unexpected close, not stopping watchdog!\n");
 184                mpcore_wdt_keepalive(wdt);
 185        }
 186        clear_bit(0, &wdt->timer_alive);
 187        wdt->expect_close = 0;
 188        return 0;
 189}
 190
 191static ssize_t mpcore_wdt_write(struct file *file, const char *data,
 192                                                size_t len, loff_t *ppos)
 193{
 194        struct mpcore_wdt *wdt = file->private_data;
 195
 196        /*
 197         *      Refresh the timer.
 198         */
 199        if (len) {
 200                if (!nowayout) {
 201                        size_t i;
 202
 203                        /* In case it was set long ago */
 204                        wdt->expect_close = 0;
 205
 206                        for (i = 0; i != len; i++) {
 207                                char c;
 208
 209                                if (get_user(c, data + i))
 210                                        return -EFAULT;
 211                                if (c == 'V')
 212                                        wdt->expect_close = 42;
 213                        }
 214                }
 215                mpcore_wdt_keepalive(wdt);
 216        }
 217        return len;
 218}
 219
 220static const struct watchdog_info ident = {
 221        .options                = WDIOF_SETTIMEOUT |
 222                                  WDIOF_KEEPALIVEPING |
 223                                  WDIOF_MAGICCLOSE,
 224        .identity               = "MPcore Watchdog",
 225};
 226
 227static long mpcore_wdt_ioctl(struct file *file, unsigned int cmd,
 228                                                        unsigned long arg)
 229{
 230        struct mpcore_wdt *wdt = file->private_data;
 231        int ret;
 232        union {
 233                struct watchdog_info ident;
 234                int i;
 235        } uarg;
 236
 237        if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
 238                return -ENOTTY;
 239
 240        if (_IOC_DIR(cmd) & _IOC_WRITE) {
 241                ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
 242                if (ret)
 243                        return -EFAULT;
 244        }
 245
 246        switch (cmd) {
 247        case WDIOC_GETSUPPORT:
 248                uarg.ident = ident;
 249                ret = 0;
 250                break;
 251
 252        case WDIOC_GETSTATUS:
 253        case WDIOC_GETBOOTSTATUS:
 254                uarg.i = 0;
 255                ret = 0;
 256                break;
 257
 258        case WDIOC_SETOPTIONS:
 259                ret = -EINVAL;
 260                if (uarg.i & WDIOS_DISABLECARD) {
 261                        mpcore_wdt_stop(wdt);
 262                        ret = 0;
 263                }
 264                if (uarg.i & WDIOS_ENABLECARD) {
 265                        mpcore_wdt_start(wdt);
 266                        ret = 0;
 267                }
 268                break;
 269
 270        case WDIOC_KEEPALIVE:
 271                mpcore_wdt_keepalive(wdt);
 272                ret = 0;
 273                break;
 274
 275        case WDIOC_SETTIMEOUT:
 276                ret = mpcore_wdt_set_heartbeat(uarg.i);
 277                if (ret)
 278                        break;
 279
 280                mpcore_wdt_keepalive(wdt);
 281                /* Fall */
 282        case WDIOC_GETTIMEOUT:
 283                uarg.i = mpcore_margin;
 284                ret = 0;
 285                break;
 286
 287        default:
 288                return -ENOTTY;
 289        }
 290
 291        if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
 292                ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
 293                if (ret)
 294                        ret = -EFAULT;
 295        }
 296        return ret;
 297}
 298
 299/*
 300 *      System shutdown handler.  Turn off the watchdog if we're
 301 *      restarting or halting the system.
 302 */
 303static void mpcore_wdt_shutdown(struct platform_device *pdev)
 304{
 305        struct mpcore_wdt *wdt = platform_get_drvdata(pdev);
 306
 307        if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
 308                mpcore_wdt_stop(wdt);
 309}
 310
 311/*
 312 *      Kernel Interfaces
 313 */
 314static const struct file_operations mpcore_wdt_fops = {
 315        .owner          = THIS_MODULE,
 316        .llseek         = no_llseek,
 317        .write          = mpcore_wdt_write,
 318        .unlocked_ioctl = mpcore_wdt_ioctl,
 319        .open           = mpcore_wdt_open,
 320        .release        = mpcore_wdt_release,
 321};
 322
 323static struct miscdevice mpcore_wdt_miscdev = {
 324        .minor          = WATCHDOG_MINOR,
 325        .name           = "watchdog",
 326        .fops           = &mpcore_wdt_fops,
 327};
 328
 329static int mpcore_wdt_probe(struct platform_device *pdev)
 330{
 331        struct mpcore_wdt *wdt;
 332        struct resource *res;
 333        int ret;
 334
 335        /* We only accept one device, and it must have an id of -1 */
 336        if (pdev->id != -1)
 337                return -ENODEV;
 338
 339        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 340        if (!res)
 341                return -ENODEV;
 342
 343        wdt = devm_kzalloc(&pdev->dev, sizeof(struct mpcore_wdt), GFP_KERNEL);
 344        if (!wdt)
 345                return -ENOMEM;
 346
 347        wdt->dev = &pdev->dev;
 348        wdt->irq = platform_get_irq(pdev, 0);
 349        if (wdt->irq >= 0) {
 350                ret = devm_request_irq(wdt->dev, wdt->irq, mpcore_wdt_fire, 0,
 351                                "mpcore_wdt", wdt);
 352                if (ret) {
 353                        dev_err(wdt->dev,
 354                                "cannot register IRQ%d for watchdog\n",
 355                                wdt->irq);
 356                        return ret;
 357                }
 358        }
 359
 360        wdt->base = devm_ioremap(wdt->dev, res->start, resource_size(res));
 361        if (!wdt->base)
 362                return -ENOMEM;
 363
 364        mpcore_wdt_miscdev.parent = &pdev->dev;
 365        ret = misc_register(&mpcore_wdt_miscdev);
 366        if (ret) {
 367                dev_err(wdt->dev,
 368                        "cannot register miscdev on minor=%d (err=%d)\n",
 369                        WATCHDOG_MINOR, ret);
 370                return ret;
 371        }
 372
 373        mpcore_wdt_stop(wdt);
 374        platform_set_drvdata(pdev, wdt);
 375        mpcore_wdt_pdev = pdev;
 376
 377        return 0;
 378}
 379
 380static int mpcore_wdt_remove(struct platform_device *pdev)
 381{
 382        platform_set_drvdata(pdev, NULL);
 383
 384        misc_deregister(&mpcore_wdt_miscdev);
 385
 386        mpcore_wdt_pdev = NULL;
 387
 388        return 0;
 389}
 390
 391#ifdef CONFIG_PM
 392static int mpcore_wdt_suspend(struct platform_device *pdev, pm_message_t msg)
 393{
 394        struct mpcore_wdt *wdt = platform_get_drvdata(pdev);
 395        mpcore_wdt_stop(wdt);           /* Turn the WDT off */
 396        return 0;
 397}
 398
 399static int mpcore_wdt_resume(struct platform_device *pdev)
 400{
 401        struct mpcore_wdt *wdt = platform_get_drvdata(pdev);
 402        /* re-activate timer */
 403        if (test_bit(0, &wdt->timer_alive))
 404                mpcore_wdt_start(wdt);
 405        return 0;
 406}
 407#else
 408#define mpcore_wdt_suspend      NULL
 409#define mpcore_wdt_resume       NULL
 410#endif
 411
 412/* work with hotplug and coldplug */
 413MODULE_ALIAS("platform:mpcore_wdt");
 414
 415static struct platform_driver mpcore_wdt_driver = {
 416        .probe          = mpcore_wdt_probe,
 417        .remove         = mpcore_wdt_remove,
 418        .suspend        = mpcore_wdt_suspend,
 419        .resume         = mpcore_wdt_resume,
 420        .shutdown       = mpcore_wdt_shutdown,
 421        .driver         = {
 422                .owner  = THIS_MODULE,
 423                .name   = "mpcore_wdt",
 424        },
 425};
 426
 427static int __init mpcore_wdt_init(void)
 428{
 429        /*
 430         * Check that the margin value is within it's range;
 431         * if not reset to the default
 432         */
 433        if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
 434                mpcore_wdt_set_heartbeat(TIMER_MARGIN);
 435                pr_info("mpcore_margin value must be 0 < mpcore_margin < 65536, using %d\n",
 436                        TIMER_MARGIN);
 437        }
 438
 439        pr_info("MPcore Watchdog Timer: 0.1. mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)\n",
 440                mpcore_noboot, mpcore_margin, nowayout);
 441
 442        return platform_driver_register(&mpcore_wdt_driver);
 443}
 444
 445static void __exit mpcore_wdt_exit(void)
 446{
 447        platform_driver_unregister(&mpcore_wdt_driver);
 448}
 449
 450module_init(mpcore_wdt_init);
 451module_exit(mpcore_wdt_exit);
 452
 453MODULE_AUTHOR("ARM Limited");
 454MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
 455MODULE_LICENSE("GPL");
 456MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 457
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