linux/drivers/watchdog/mpc8xxx_wdt.c
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   1/*
   2 * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface
   3 *
   4 * Authors: Dave Updegraff <dave@cray.org>
   5 *          Kumar Gala <galak@kernel.crashing.org>
   6 *              Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>
   7 *                              ..and from sc520_wdt
   8 * Copyright (c) 2008  MontaVista Software, Inc.
   9 *                     Anton Vorontsov <avorontsov@ru.mvista.com>
  10 *
  11 * Note: it appears that you can only actually ENABLE or DISABLE the thing
  12 * once after POR. Once enabled, you cannot disable, and vice versa.
  13 *
  14 * This program is free software; you can redistribute  it and/or modify it
  15 * under  the terms of  the GNU General  Public License as published by the
  16 * Free Software Foundation;  either version 2 of the  License, or (at your
  17 * option) any later version.
  18 */
  19
  20#include <linux/fs.h>
  21#include <linux/init.h>
  22#include <linux/kernel.h>
  23#include <linux/timer.h>
  24#include <linux/miscdevice.h>
  25#include <linux/of_platform.h>
  26#include <linux/module.h>
  27#include <linux/watchdog.h>
  28#include <linux/io.h>
  29#include <linux/uaccess.h>
  30#include <sysdev/fsl_soc.h>
  31
  32struct mpc8xxx_wdt {
  33        __be32 res0;
  34        __be32 swcrr; /* System watchdog control register */
  35#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
  36#define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
  37#define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
  38#define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
  39        __be32 swcnr; /* System watchdog count register */
  40        u8 res1[2];
  41        __be16 swsrr; /* System watchdog service register */
  42        u8 res2[0xF0];
  43};
  44
  45struct mpc8xxx_wdt_type {
  46        int prescaler;
  47        bool hw_enabled;
  48};
  49
  50static struct mpc8xxx_wdt __iomem *wd_base;
  51static int mpc8xxx_wdt_init_late(void);
  52
  53static u16 timeout = 0xffff;
  54module_param(timeout, ushort, 0);
  55MODULE_PARM_DESC(timeout,
  56        "Watchdog timeout in ticks. (0<timeout<65536, default=65535)");
  57
  58static int reset = 1;
  59module_param(reset, bool, 0);
  60MODULE_PARM_DESC(reset,
  61        "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
  62
  63static int nowayout = WATCHDOG_NOWAYOUT;
  64module_param(nowayout, int, 0);
  65MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  66                 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  67
  68/*
  69 * We always prescale, but if someone really doesn't want to they can set this
  70 * to 0
  71 */
  72static int prescale = 1;
  73static unsigned int timeout_sec;
  74
  75static unsigned long wdt_is_open;
  76static DEFINE_SPINLOCK(wdt_spinlock);
  77
  78static void mpc8xxx_wdt_keepalive(void)
  79{
  80        /* Ping the WDT */
  81        spin_lock(&wdt_spinlock);
  82        out_be16(&wd_base->swsrr, 0x556c);
  83        out_be16(&wd_base->swsrr, 0xaa39);
  84        spin_unlock(&wdt_spinlock);
  85}
  86
  87static void mpc8xxx_wdt_timer_ping(unsigned long arg);
  88static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
  89
  90static void mpc8xxx_wdt_timer_ping(unsigned long arg)
  91{
  92        mpc8xxx_wdt_keepalive();
  93        /* We're pinging it twice faster than needed, just to be sure. */
  94        mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
  95}
  96
  97static void mpc8xxx_wdt_pr_warn(const char *msg)
  98{
  99        pr_crit("mpc8xxx_wdt: %s, expect the %s soon!\n", msg,
 100                reset ? "reset" : "machine check exception");
 101}
 102
 103static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
 104                                 size_t count, loff_t *ppos)
 105{
 106        if (count)
 107                mpc8xxx_wdt_keepalive();
 108        return count;
 109}
 110
 111static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
 112{
 113        u32 tmp = SWCRR_SWEN;
 114        if (test_and_set_bit(0, &wdt_is_open))
 115                return -EBUSY;
 116
 117        /* Once we start the watchdog we can't stop it */
 118        if (nowayout)
 119                __module_get(THIS_MODULE);
 120
 121        /* Good, fire up the show */
 122        if (prescale)
 123                tmp |= SWCRR_SWPR;
 124        if (reset)
 125                tmp |= SWCRR_SWRI;
 126
 127        tmp |= timeout << 16;
 128
 129        out_be32(&wd_base->swcrr, tmp);
 130
 131        del_timer_sync(&wdt_timer);
 132
 133        return nonseekable_open(inode, file);
 134}
 135
 136static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
 137{
 138        if (!nowayout)
 139                mpc8xxx_wdt_timer_ping(0);
 140        else
 141                mpc8xxx_wdt_pr_warn("watchdog closed");
 142        clear_bit(0, &wdt_is_open);
 143        return 0;
 144}
 145
 146static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
 147                                                        unsigned long arg)
 148{
 149        void __user *argp = (void __user *)arg;
 150        int __user *p = argp;
 151        static const struct watchdog_info ident = {
 152                .options = WDIOF_KEEPALIVEPING,
 153                .firmware_version = 1,
 154                .identity = "MPC8xxx",
 155        };
 156
 157        switch (cmd) {
 158        case WDIOC_GETSUPPORT:
 159                return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 160        case WDIOC_GETSTATUS:
 161        case WDIOC_GETBOOTSTATUS:
 162                return put_user(0, p);
 163        case WDIOC_KEEPALIVE:
 164                mpc8xxx_wdt_keepalive();
 165                return 0;
 166        case WDIOC_GETTIMEOUT:
 167                return put_user(timeout_sec, p);
 168        default:
 169                return -ENOTTY;
 170        }
 171}
 172
 173static const struct file_operations mpc8xxx_wdt_fops = {
 174        .owner          = THIS_MODULE,
 175        .llseek         = no_llseek,
 176        .write          = mpc8xxx_wdt_write,
 177        .unlocked_ioctl = mpc8xxx_wdt_ioctl,
 178        .open           = mpc8xxx_wdt_open,
 179        .release        = mpc8xxx_wdt_release,
 180};
 181
 182static struct miscdevice mpc8xxx_wdt_miscdev = {
 183        .minor  = WATCHDOG_MINOR,
 184        .name   = "watchdog",
 185        .fops   = &mpc8xxx_wdt_fops,
 186};
 187
 188static int __devinit mpc8xxx_wdt_probe(struct platform_device *ofdev,
 189                                       const struct of_device_id *match)
 190{
 191        int ret;
 192        struct device_node *np = ofdev->dev.of_node;
 193        struct mpc8xxx_wdt_type *wdt_type = match->data;
 194        u32 freq = fsl_get_sys_freq();
 195        bool enabled;
 196
 197        if (!freq || freq == -1)
 198                return -EINVAL;
 199
 200        wd_base = of_iomap(np, 0);
 201        if (!wd_base)
 202                return -ENOMEM;
 203
 204        enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
 205        if (!enabled && wdt_type->hw_enabled) {
 206                pr_info("mpc8xxx_wdt: could not be enabled in software\n");
 207                ret = -ENOSYS;
 208                goto err_unmap;
 209        }
 210
 211        /* Calculate the timeout in seconds */
 212        if (prescale)
 213                timeout_sec = (timeout * wdt_type->prescaler) / freq;
 214        else
 215                timeout_sec = timeout / freq;
 216
 217#ifdef MODULE
 218        ret = mpc8xxx_wdt_init_late();
 219        if (ret)
 220                goto err_unmap;
 221#endif
 222
 223        pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d "
 224                "(%d seconds)\n", reset ? "reset" : "interrupt", timeout,
 225                timeout_sec);
 226
 227        /*
 228         * If the watchdog was previously enabled or we're running on
 229         * MPC8xxx, we should ping the wdt from the kernel until the
 230         * userspace handles it.
 231         */
 232        if (enabled)
 233                mpc8xxx_wdt_timer_ping(0);
 234        return 0;
 235err_unmap:
 236        iounmap(wd_base);
 237        wd_base = NULL;
 238        return ret;
 239}
 240
 241static int __devexit mpc8xxx_wdt_remove(struct platform_device *ofdev)
 242{
 243        mpc8xxx_wdt_pr_warn("watchdog removed");
 244        del_timer_sync(&wdt_timer);
 245        misc_deregister(&mpc8xxx_wdt_miscdev);
 246        iounmap(wd_base);
 247
 248        return 0;
 249}
 250
 251static const struct of_device_id mpc8xxx_wdt_match[] = {
 252        {
 253                .compatible = "mpc83xx_wdt",
 254                .data = &(struct mpc8xxx_wdt_type) {
 255                        .prescaler = 0x10000,
 256                },
 257        },
 258        {
 259                .compatible = "fsl,mpc8610-wdt",
 260                .data = &(struct mpc8xxx_wdt_type) {
 261                        .prescaler = 0x10000,
 262                        .hw_enabled = true,
 263                },
 264        },
 265        {
 266                .compatible = "fsl,mpc823-wdt",
 267                .data = &(struct mpc8xxx_wdt_type) {
 268                        .prescaler = 0x800,
 269                },
 270        },
 271        {},
 272};
 273MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
 274
 275static struct of_platform_driver mpc8xxx_wdt_driver = {
 276        .probe          = mpc8xxx_wdt_probe,
 277        .remove         = __devexit_p(mpc8xxx_wdt_remove),
 278        .driver = {
 279                .name = "mpc8xxx_wdt",
 280                .owner = THIS_MODULE,
 281                .of_match_table = mpc8xxx_wdt_match,
 282        },
 283};
 284
 285/*
 286 * We do wdt initialization in two steps: arch_initcall probes the wdt
 287 * very early to start pinging the watchdog (misc devices are not yet
 288 * available), and later module_init() just registers the misc device.
 289 */
 290static int mpc8xxx_wdt_init_late(void)
 291{
 292        int ret;
 293
 294        if (!wd_base)
 295                return -ENODEV;
 296
 297        ret = misc_register(&mpc8xxx_wdt_miscdev);
 298        if (ret) {
 299                pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 300                        WATCHDOG_MINOR, ret);
 301                return ret;
 302        }
 303        return 0;
 304}
 305#ifndef MODULE
 306module_init(mpc8xxx_wdt_init_late);
 307#endif
 308
 309static int __init mpc8xxx_wdt_init(void)
 310{
 311        return of_register_platform_driver(&mpc8xxx_wdt_driver);
 312}
 313arch_initcall(mpc8xxx_wdt_init);
 314
 315static void __exit mpc8xxx_wdt_exit(void)
 316{
 317        of_unregister_platform_driver(&mpc8xxx_wdt_driver);
 318}
 319module_exit(mpc8xxx_wdt_exit);
 320
 321MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
 322MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
 323                   "uProcessors");
 324MODULE_LICENSE("GPL");
 325MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 326