linux/drivers/watchdog/iop_wdt.c
<<
>>
Prefs
   1/*
   2 * drivers/char/watchdog/iop_wdt.c
   3 *
   4 * WDT driver for Intel I/O Processors
   5 * Copyright (C) 2005, Intel Corporation.
   6 *
   7 * Based on ixp4xx driver, Copyright 2004 (c) MontaVista, Software, Inc.
   8 *
   9 * This program is free software; you can redistribute it and/or modify it
  10 * under the terms and conditions of the GNU General Public License,
  11 * version 2, as published by the Free Software Foundation.
  12 *
  13 * This program is distributed in the hope it will be useful, but WITHOUT
  14 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  16 * more details.
  17 *
  18 * You should have received a copy of the GNU General Public License along with
  19 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  20 * Place - Suite 330, Boston, MA 02111-1307 USA.
  21 *
  22 *      Curt E Bruns <curt.e.bruns@intel.com>
  23 *      Peter Milne <peter.milne@d-tacq.com>
  24 *      Dan Williams <dan.j.williams@intel.com>
  25 */
  26
  27#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  28
  29#include <linux/module.h>
  30#include <linux/kernel.h>
  31#include <linux/fs.h>
  32#include <linux/init.h>
  33#include <linux/device.h>
  34#include <linux/miscdevice.h>
  35#include <linux/watchdog.h>
  36#include <linux/uaccess.h>
  37#include <mach/hardware.h>
  38
  39static bool nowayout = WATCHDOG_NOWAYOUT;
  40static unsigned long wdt_status;
  41static unsigned long boot_status;
  42static DEFINE_SPINLOCK(wdt_lock);
  43
  44#define WDT_IN_USE              0
  45#define WDT_OK_TO_CLOSE         1
  46#define WDT_ENABLED             2
  47
  48static unsigned long iop_watchdog_timeout(void)
  49{
  50        return (0xffffffffUL / get_iop_tick_rate());
  51}
  52
  53/**
  54 * wdt_supports_disable - determine if we are accessing a iop13xx watchdog
  55 * or iop3xx by whether it has a disable command
  56 */
  57static int wdt_supports_disable(void)
  58{
  59        int can_disable;
  60
  61        if (IOP_WDTCR_EN_ARM != IOP_WDTCR_DIS_ARM)
  62                can_disable = 1;
  63        else
  64                can_disable = 0;
  65
  66        return can_disable;
  67}
  68
  69static void wdt_enable(void)
  70{
  71        /* Arm and enable the Timer to starting counting down from 0xFFFF.FFFF
  72         * Takes approx. 10.7s to timeout
  73         */
  74        spin_lock(&wdt_lock);
  75        write_wdtcr(IOP_WDTCR_EN_ARM);
  76        write_wdtcr(IOP_WDTCR_EN);
  77        spin_unlock(&wdt_lock);
  78}
  79
  80/* returns 0 if the timer was successfully disabled */
  81static int wdt_disable(void)
  82{
  83        /* Stop Counting */
  84        if (wdt_supports_disable()) {
  85                spin_lock(&wdt_lock);
  86                write_wdtcr(IOP_WDTCR_DIS_ARM);
  87                write_wdtcr(IOP_WDTCR_DIS);
  88                clear_bit(WDT_ENABLED, &wdt_status);
  89                spin_unlock(&wdt_lock);
  90                pr_info("Disabled\n");
  91                return 0;
  92        } else
  93                return 1;
  94}
  95
  96static int iop_wdt_open(struct inode *inode, struct file *file)
  97{
  98        if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  99                return -EBUSY;
 100
 101        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 102        wdt_enable();
 103        set_bit(WDT_ENABLED, &wdt_status);
 104        return nonseekable_open(inode, file);
 105}
 106
 107static ssize_t iop_wdt_write(struct file *file, const char *data, size_t len,
 108                  loff_t *ppos)
 109{
 110        if (len) {
 111                if (!nowayout) {
 112                        size_t i;
 113
 114                        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 115
 116                        for (i = 0; i != len; i++) {
 117                                char c;
 118
 119                                if (get_user(c, data + i))
 120                                        return -EFAULT;
 121                                if (c == 'V')
 122                                        set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 123                        }
 124                }
 125                wdt_enable();
 126        }
 127        return len;
 128}
 129
 130static const struct watchdog_info ident = {
 131        .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 132        .identity = "iop watchdog",
 133};
 134
 135static long iop_wdt_ioctl(struct file *file,
 136                                unsigned int cmd, unsigned long arg)
 137{
 138        int options;
 139        int ret = -ENOTTY;
 140        int __user *argp = (int __user *)arg;
 141
 142        switch (cmd) {
 143        case WDIOC_GETSUPPORT:
 144                if (copy_to_user(argp, &ident, sizeof(ident)))
 145                        ret = -EFAULT;
 146                else
 147                        ret = 0;
 148                break;
 149
 150        case WDIOC_GETSTATUS:
 151                ret = put_user(0, argp);
 152                break;
 153
 154        case WDIOC_GETBOOTSTATUS:
 155                ret = put_user(boot_status, argp);
 156                break;
 157
 158        case WDIOC_SETOPTIONS:
 159                if (get_user(options, (int *)arg))
 160                        return -EFAULT;
 161
 162                if (options & WDIOS_DISABLECARD) {
 163                        if (!nowayout) {
 164                                if (wdt_disable() == 0) {
 165                                        set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 166                                        ret = 0;
 167                                } else
 168                                        ret = -ENXIO;
 169                        } else
 170                                ret = 0;
 171                }
 172                if (options & WDIOS_ENABLECARD) {
 173                        wdt_enable();
 174                        ret = 0;
 175                }
 176                break;
 177
 178        case WDIOC_KEEPALIVE:
 179                wdt_enable();
 180                ret = 0;
 181                break;
 182
 183        case WDIOC_GETTIMEOUT:
 184                ret = put_user(iop_watchdog_timeout(), argp);
 185                break;
 186        }
 187        return ret;
 188}
 189
 190static int iop_wdt_release(struct inode *inode, struct file *file)
 191{
 192        int state = 1;
 193        if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 194                if (test_bit(WDT_ENABLED, &wdt_status))
 195                        state = wdt_disable();
 196
 197        /* if the timer is not disabled reload and notify that we are still
 198         * going down
 199         */
 200        if (state != 0) {
 201                wdt_enable();
 202                pr_crit("Device closed unexpectedly - reset in %lu seconds\n",
 203                        iop_watchdog_timeout());
 204        }
 205
 206        clear_bit(WDT_IN_USE, &wdt_status);
 207        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 208
 209        return 0;
 210}
 211
 212static const struct file_operations iop_wdt_fops = {
 213        .owner = THIS_MODULE,
 214        .llseek = no_llseek,
 215        .write = iop_wdt_write,
 216        .unlocked_ioctl = iop_wdt_ioctl,
 217        .open = iop_wdt_open,
 218        .release = iop_wdt_release,
 219};
 220
 221static struct miscdevice iop_wdt_miscdev = {
 222        .minor = WATCHDOG_MINOR,
 223        .name = "watchdog",
 224        .fops = &iop_wdt_fops,
 225};
 226
 227static int __init iop_wdt_init(void)
 228{
 229        int ret;
 230
 231        /* check if the reset was caused by the watchdog timer */
 232        boot_status = (read_rcsr() & IOP_RCSR_WDT) ? WDIOF_CARDRESET : 0;
 233
 234        /* Configure Watchdog Timeout to cause an Internal Bus (IB) Reset
 235         * NOTE: An IB Reset will Reset both cores in the IOP342
 236         */
 237        write_wdtsr(IOP13XX_WDTCR_IB_RESET);
 238
 239        /* Register after we have the device set up so we cannot race
 240           with an open */
 241        ret = misc_register(&iop_wdt_miscdev);
 242        if (ret == 0)
 243                pr_info("timeout %lu sec\n", iop_watchdog_timeout());
 244
 245        return ret;
 246}
 247
 248static void __exit iop_wdt_exit(void)
 249{
 250        misc_deregister(&iop_wdt_miscdev);
 251}
 252
 253module_init(iop_wdt_init);
 254module_exit(iop_wdt_exit);
 255
 256module_param(nowayout, bool, 0);
 257MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 258
 259MODULE_AUTHOR("Curt E Bruns <curt.e.bruns@intel.com>");
 260MODULE_DESCRIPTION("iop watchdog timer driver");
 261MODULE_LICENSE("GPL");
 262MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 263
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.