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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22#include <linux/fs.h>
  23#include <linux/init.h>
  24#include <linux/kernel.h>
  25#include <linux/timer.h>
  26#include <linux/miscdevice.h>
  27#include <linux/of_platform.h>
  28#include <linux/module.h>
  29#include <linux/watchdog.h>
  30#include <linux/io.h>
  31#include <linux/uaccess.h>
  32#include <sysdev/fsl_soc.h>
  33
  34struct mpc8xxx_wdt {
  35        __be32 res0;
  36        __be32 swcrr; /* System watchdog control register */
  37#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
  38#define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
  39#define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
  40#define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
  41        __be32 swcnr; /* System watchdog count register */
  42        u8 res1[2];
  43        __be16 swsrr; /* System watchdog service register */
  44        u8 res2[0xF0];
  45};
  46
  47struct mpc8xxx_wdt_type {
  48        int prescaler;
  49        bool hw_enabled;
  50};
  51
  52static struct mpc8xxx_wdt __iomem *wd_base;
  53static int mpc8xxx_wdt_init_late(void);
  54
  55static u16 timeout = 0xffff;
  56module_param(timeout, ushort, 0);
  57MODULE_PARM_DESC(timeout,
  58        "Watchdog timeout in ticks. (0<timeout<65536, default=65535)");
  59
  60static bool reset = 1;
  61module_param(reset, bool, 0);
  62MODULE_PARM_DESC(reset,
  63        "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
  64
  65static bool nowayout = WATCHDOG_NOWAYOUT;
  66module_param(nowayout, bool, 0);
  67MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  68                 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  69
  70/*
  71 * We always prescale, but if someone really doesn't want to they can set this
  72 * to 0
  73 */
  74static int prescale = 1;
  75static unsigned int timeout_sec;
  76
  77static unsigned long wdt_is_open;
  78static DEFINE_SPINLOCK(wdt_spinlock);
  79
  80static void mpc8xxx_wdt_keepalive(void)
  81{
  82        /* Ping the WDT */
  83        spin_lock(&wdt_spinlock);
  84        out_be16(&wd_base->swsrr, 0x556c);
  85        out_be16(&wd_base->swsrr, 0xaa39);
  86        spin_unlock(&wdt_spinlock);
  87}
  88
  89static void mpc8xxx_wdt_timer_ping(unsigned long arg);
  90static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
  91
  92static void mpc8xxx_wdt_timer_ping(unsigned long arg)
  93{
  94        mpc8xxx_wdt_keepalive();
  95        /* We're pinging it twice faster than needed, just to be sure. */
  96        mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
  97}
  98
  99static void mpc8xxx_wdt_pr_warn(const char *msg)
 100{
 101        pr_crit("%s, expect the %s soon!\n", msg,
 102                reset ? "reset" : "machine check exception");
 103}
 104
 105static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
 106                                 size_t count, loff_t *ppos)
 107{
 108        if (count)
 109                mpc8xxx_wdt_keepalive();
 110        return count;
 111}
 112
 113static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
 114{
 115        u32 tmp = SWCRR_SWEN;
 116        if (test_and_set_bit(0, &wdt_is_open))
 117                return -EBUSY;
 118
 119        /* Once we start the watchdog we can't stop it */
 120        if (nowayout)
 121                __module_get(THIS_MODULE);
 122
 123        /* Good, fire up the show */
 124        if (prescale)
 125                tmp |= SWCRR_SWPR;
 126        if (reset)
 127                tmp |= SWCRR_SWRI;
 128
 129        tmp |= timeout << 16;
 130
 131        out_be32(&wd_base->swcrr, tmp);
 132
 133        del_timer_sync(&wdt_timer);
 134
 135        return nonseekable_open(inode, file);
 136}
 137
 138static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
 139{
 140        if (!nowayout)
 141                mpc8xxx_wdt_timer_ping(0);
 142        else
 143                mpc8xxx_wdt_pr_warn("watchdog closed");
 144        clear_bit(0, &wdt_is_open);
 145        return 0;
 146}
 147
 148static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
 149                                                        unsigned long arg)
 150{
 151        void __user *argp = (void __user *)arg;
 152        int __user *p = argp;
 153        static const struct watchdog_info ident = {
 154                .options = WDIOF_KEEPALIVEPING,
 155                .firmware_version = 1,
 156                .identity = "MPC8xxx",
 157        };
 158
 159        switch (cmd) {
 160        case WDIOC_GETSUPPORT:
 161                return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 162        case WDIOC_GETSTATUS:
 163        case WDIOC_GETBOOTSTATUS:
 164                return put_user(0, p);
 165        case WDIOC_KEEPALIVE:
 166                mpc8xxx_wdt_keepalive();
 167                return 0;
 168        case WDIOC_GETTIMEOUT:
 169                return put_user(timeout_sec, p);
 170        default:
 171                return -ENOTTY;
 172        }
 173}
 174
 175static const struct file_operations mpc8xxx_wdt_fops = {
 176        .owner          = THIS_MODULE,
 177        .llseek         = no_llseek,
 178        .write          = mpc8xxx_wdt_write,
 179        .unlocked_ioctl = mpc8xxx_wdt_ioctl,
 180        .open           = mpc8xxx_wdt_open,
 181        .release        = mpc8xxx_wdt_release,
 182};
 183
 184static struct miscdevice mpc8xxx_wdt_miscdev = {
 185        .minor  = WATCHDOG_MINOR,
 186        .name   = "watchdog",
 187        .fops   = &mpc8xxx_wdt_fops,
 188};
 189
 190static const struct of_device_id mpc8xxx_wdt_match[];
 191static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
 192{
 193        int ret;
 194        const struct of_device_id *match;
 195        struct device_node *np = ofdev->dev.of_node;
 196        const struct mpc8xxx_wdt_type *wdt_type;
 197        u32 freq = fsl_get_sys_freq();
 198        bool enabled;
 199
 200        match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
 201        if (!match)
 202                return -EINVAL;
 203        wdt_type = match->data;
 204
 205        if (!freq || freq == -1)
 206                return -EINVAL;
 207
 208        wd_base = of_iomap(np, 0);
 209        if (!wd_base)
 210                return -ENOMEM;
 211
 212        enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
 213        if (!enabled && wdt_type->hw_enabled) {
 214                pr_info("could not be enabled in software\n");
 215                ret = -ENOSYS;
 216                goto err_unmap;
 217        }
 218
 219        /* Calculate the timeout in seconds */
 220        if (prescale)
 221                timeout_sec = (timeout * wdt_type->prescaler) / freq;
 222        else
 223                timeout_sec = timeout / freq;
 224
 225#ifdef MODULE
 226        ret = mpc8xxx_wdt_init_late();
 227        if (ret)
 228                goto err_unmap;
 229#endif
 230
 231        pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n",
 232                reset ? "reset" : "interrupt", timeout, timeout_sec);
 233
 234        /*
 235         * If the watchdog was previously enabled or we're running on
 236         * MPC8xxx, we should ping the wdt from the kernel until the
 237         * userspace handles it.
 238         */
 239        if (enabled)
 240                mpc8xxx_wdt_timer_ping(0);
 241        return 0;
 242err_unmap:
 243        iounmap(wd_base);
 244        wd_base = NULL;
 245        return ret;
 246}
 247
 248static int mpc8xxx_wdt_remove(struct platform_device *ofdev)
 249{
 250        mpc8xxx_wdt_pr_warn("watchdog removed");
 251        del_timer_sync(&wdt_timer);
 252        misc_deregister(&mpc8xxx_wdt_miscdev);
 253        iounmap(wd_base);
 254
 255        return 0;
 256}
 257
 258static const struct of_device_id mpc8xxx_wdt_match[] = {
 259        {
 260                .compatible = "mpc83xx_wdt",
 261                .data = &(struct mpc8xxx_wdt_type) {
 262                        .prescaler = 0x10000,
 263                },
 264        },
 265        {
 266                .compatible = "fsl,mpc8610-wdt",
 267                .data = &(struct mpc8xxx_wdt_type) {
 268                        .prescaler = 0x10000,
 269                        .hw_enabled = true,
 270                },
 271        },
 272        {
 273                .compatible = "fsl,mpc823-wdt",
 274                .data = &(struct mpc8xxx_wdt_type) {
 275                        .prescaler = 0x800,
 276                },
 277        },
 278        {},
 279};
 280MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);
 281
 282static struct platform_driver mpc8xxx_wdt_driver = {
 283        .probe          = mpc8xxx_wdt_probe,
 284        .remove         = mpc8xxx_wdt_remove,
 285        .driver = {
 286                .name = "mpc8xxx_wdt",
 287                .owner = THIS_MODULE,
 288                .of_match_table = mpc8xxx_wdt_match,
 289        },
 290};
 291
 292/*
 293 * We do wdt initialization in two steps: arch_initcall probes the wdt
 294 * very early to start pinging the watchdog (misc devices are not yet
 295 * available), and later module_init() just registers the misc device.
 296 */
 297static int mpc8xxx_wdt_init_late(void)
 298{
 299        int ret;
 300
 301        if (!wd_base)
 302                return -ENODEV;
 303
 304        ret = misc_register(&mpc8xxx_wdt_miscdev);
 305        if (ret) {
 306                pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 307                       WATCHDOG_MINOR, ret);
 308                return ret;
 309        }
 310        return 0;
 311}
 312#ifndef MODULE
 313module_init(mpc8xxx_wdt_init_late);
 314#endif
 315
 316static int __init mpc8xxx_wdt_init(void)
 317{
 318        return platform_driver_register(&mpc8xxx_wdt_driver);
 319}
 320arch_initcall(mpc8xxx_wdt_init);
 321
 322static void __exit mpc8xxx_wdt_exit(void)
 323{
 324        platform_driver_unregister(&mpc8xxx_wdt_driver);
 325}
 326module_exit(mpc8xxx_wdt_exit);
 327
 328MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
 329MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
 330                   "uProcessors");
 331MODULE_LICENSE("GPL");
 332MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 333
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