linux/drivers/watchdog/ixp4xx_wdt.c
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   1/*
   2 * drivers/char/watchdog/ixp4xx_wdt.c
   3 *
   4 * Watchdog driver for Intel IXP4xx network processors
   5 *
   6 * Author: Deepak Saxena <dsaxena@plexity.net>
   7 *
   8 * Copyright 2004 (c) MontaVista, Software, Inc.
   9 * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17
  18#include <linux/module.h>
  19#include <linux/moduleparam.h>
  20#include <linux/types.h>
  21#include <linux/kernel.h>
  22#include <linux/fs.h>
  23#include <linux/miscdevice.h>
  24#include <linux/watchdog.h>
  25#include <linux/init.h>
  26#include <linux/bitops.h>
  27#include <linux/uaccess.h>
  28#include <mach/hardware.h>
  29
  30static bool nowayout = WATCHDOG_NOWAYOUT;
  31static int heartbeat = 60;      /* (secs) Default is 1 minute */
  32static unsigned long wdt_status;
  33static unsigned long boot_status;
  34static DEFINE_SPINLOCK(wdt_lock);
  35
  36#define WDT_TICK_RATE (IXP4XX_PERIPHERAL_BUS_CLOCK * 1000000UL)
  37
  38#define WDT_IN_USE              0
  39#define WDT_OK_TO_CLOSE         1
  40
  41static void wdt_enable(void)
  42{
  43        spin_lock(&wdt_lock);
  44        *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  45        *IXP4XX_OSWE = 0;
  46        *IXP4XX_OSWT = WDT_TICK_RATE * heartbeat;
  47        *IXP4XX_OSWE = IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE;
  48        *IXP4XX_OSWK = 0;
  49        spin_unlock(&wdt_lock);
  50}
  51
  52static void wdt_disable(void)
  53{
  54        spin_lock(&wdt_lock);
  55        *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  56        *IXP4XX_OSWE = 0;
  57        *IXP4XX_OSWK = 0;
  58        spin_unlock(&wdt_lock);
  59}
  60
  61static int ixp4xx_wdt_open(struct inode *inode, struct file *file)
  62{
  63        if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  64                return -EBUSY;
  65
  66        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  67        wdt_enable();
  68        return nonseekable_open(inode, file);
  69}
  70
  71static ssize_t
  72ixp4xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  73{
  74        if (len) {
  75                if (!nowayout) {
  76                        size_t i;
  77
  78                        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  79
  80                        for (i = 0; i != len; i++) {
  81                                char c;
  82
  83                                if (get_user(c, data + i))
  84                                        return -EFAULT;
  85                                if (c == 'V')
  86                                        set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  87                        }
  88                }
  89                wdt_enable();
  90        }
  91        return len;
  92}
  93
  94static const struct watchdog_info ident = {
  95        .options        = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
  96                          WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  97        .identity       = "IXP4xx Watchdog",
  98};
  99
 100
 101static long ixp4xx_wdt_ioctl(struct file *file, unsigned int cmd,
 102                                                        unsigned long arg)
 103{
 104        int ret = -ENOTTY;
 105        int time;
 106
 107        switch (cmd) {
 108        case WDIOC_GETSUPPORT:
 109                ret = copy_to_user((struct watchdog_info *)arg, &ident,
 110                                   sizeof(ident)) ? -EFAULT : 0;
 111                break;
 112
 113        case WDIOC_GETSTATUS:
 114                ret = put_user(0, (int *)arg);
 115                break;
 116
 117        case WDIOC_GETBOOTSTATUS:
 118                ret = put_user(boot_status, (int *)arg);
 119                break;
 120
 121        case WDIOC_KEEPALIVE:
 122                wdt_enable();
 123                ret = 0;
 124                break;
 125
 126        case WDIOC_SETTIMEOUT:
 127                ret = get_user(time, (int *)arg);
 128                if (ret)
 129                        break;
 130
 131                if (time <= 0 || time > 60) {
 132                        ret = -EINVAL;
 133                        break;
 134                }
 135
 136                heartbeat = time;
 137                wdt_enable();
 138                /* Fall through */
 139
 140        case WDIOC_GETTIMEOUT:
 141                ret = put_user(heartbeat, (int *)arg);
 142                break;
 143        }
 144        return ret;
 145}
 146
 147static int ixp4xx_wdt_release(struct inode *inode, struct file *file)
 148{
 149        if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 150                wdt_disable();
 151        else
 152                pr_crit("Device closed unexpectedly - timer will not stop\n");
 153        clear_bit(WDT_IN_USE, &wdt_status);
 154        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 155
 156        return 0;
 157}
 158
 159
 160static const struct file_operations ixp4xx_wdt_fops = {
 161        .owner          = THIS_MODULE,
 162        .llseek         = no_llseek,
 163        .write          = ixp4xx_wdt_write,
 164        .unlocked_ioctl = ixp4xx_wdt_ioctl,
 165        .open           = ixp4xx_wdt_open,
 166        .release        = ixp4xx_wdt_release,
 167};
 168
 169static struct miscdevice ixp4xx_wdt_miscdev = {
 170        .minor          = WATCHDOG_MINOR,
 171        .name           = "watchdog",
 172        .fops           = &ixp4xx_wdt_fops,
 173};
 174
 175static int __init ixp4xx_wdt_init(void)
 176{
 177        int ret;
 178
 179        if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) {
 180                pr_err("Rev. A0 IXP42x CPU detected - watchdog disabled\n");
 181
 182                return -ENODEV;
 183        }
 184        boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ?
 185                        WDIOF_CARDRESET : 0;
 186        ret = misc_register(&ixp4xx_wdt_miscdev);
 187        if (ret == 0)
 188                pr_info("timer heartbeat %d sec\n", heartbeat);
 189        return ret;
 190}
 191
 192static void __exit ixp4xx_wdt_exit(void)
 193{
 194        misc_deregister(&ixp4xx_wdt_miscdev);
 195}
 196
 197
 198module_init(ixp4xx_wdt_init);
 199module_exit(ixp4xx_wdt_exit);
 200
 201MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 202MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
 203
 204module_param(heartbeat, int, 0);
 205MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 206
 207module_param(nowayout, bool, 0);
 208MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 209
 210MODULE_LICENSE("GPL");
 211MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 212
 213
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