drivers/char/watchdog/ixp2000_wdt.c

   1 /*
   2  * drivers/watchdog/ixp2000_wdt.c
   3  *
   4  * Watchdog driver for Intel IXP2000 network processors
   5  *
   6  * Adapted from the IXP4xx watchdog driver by Lennert Buytenhek.
   7  * The original version carries these notices:
   8  *
   9  * Author: Deepak Saxena <dsaxena@plexity.net>
  10  *
  11  * Copyright 2004 (c) MontaVista, Software, Inc.
  12  * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  13  *
  14  * This file is licensed under  the terms of the GNU General Public
  15  * License version 2. This program is licensed "as is" without any
  16  * warranty of any kind, whether express or implied.
  17  */
  18
  19 #include <linux/config.h>
  20 #include <linux/module.h>
  21 #include <linux/moduleparam.h>
  22 #include <linux/types.h>
  23 #include <linux/kernel.h>
  24 #include <linux/fs.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/watchdog.h>
  27 #include <linux/init.h>
  28 #include <linux/bitops.h>
  29
  30 #include <asm/hardware.h>
  31 #include <asm/uaccess.h>
  32
  33 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  34 static int nowayout = 1;
  35 #else
  36 static int nowayout = 0;
  37 #endif
  38 static unsigned int heartbeat = 60;     /* (secs) Default is 1 minute */
  39 static unsigned long wdt_status;
  40
  41 #define WDT_IN_USE              0
  42 #define WDT_OK_TO_CLOSE         1
  43
  44 static unsigned long wdt_tick_rate;
  45
  46 static void
  47 wdt_enable(void)
  48 {
  49         ixp2000_reg_write(IXP2000_RESET0, *(IXP2000_RESET0) | WDT_RESET_ENABLE);
  50         ixp2000_reg_write(IXP2000_TWDE, WDT_ENABLE);
  51         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
  52         ixp2000_reg_write(IXP2000_T4_CTL, TIMER_DIVIDER_256 | TIMER_ENABLE);
  53 }
  54
  55 static void
  56 wdt_disable(void)
  57 {
  58         ixp2000_reg_write(IXP2000_T4_CTL, 0);
  59 }
  60
  61 static void
  62 wdt_keepalive(void)
  63 {
  64         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
  65 }
  66
  67 static int
  68 ixp2000_wdt_open(struct inode *inode, struct file *file)
  69 {
  70         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  71                 return -EBUSY;
  72
  73         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  74
  75         wdt_enable();
  76
  77         return nonseekable_open(inode, file);
  78 }
  79
  80 static ssize_t
  81 ixp2000_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  82 {
  83         if (len) {
  84                 if (!nowayout) {
  85                         size_t i;
  86
  87                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  88
  89                         for (i = 0; i != len; i++) {
  90                                 char c;
  91
  92                                 if (get_user(c, data + i))
  93                                         return -EFAULT;
  94                                 if (c == 'V')
  95                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  96                         }
  97                 }
  98                 wdt_keepalive();
  99         }
 100
 101         return len;
 102 }
 103
 104
 105 static struct watchdog_info ident = {
 106         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 107                                 WDIOF_KEEPALIVEPING,
 108         .identity       = "IXP2000 Watchdog",
 109 };
 110
 111 static int
 112 ixp2000_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 113                         unsigned long arg)
 114 {
 115         int ret = -ENOIOCTLCMD;
 116         int time;
 117
 118         switch (cmd) {
 119         case WDIOC_GETSUPPORT:
 120                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 121                                    sizeof(ident)) ? -EFAULT : 0;
 122                 break;
 123
 124         case WDIOC_GETSTATUS:
 125                 ret = put_user(0, (int *)arg);
 126                 break;
 127
 128         case WDIOC_GETBOOTSTATUS:
 129                 ret = put_user(0, (int *)arg);
 130                 break;
 131
 132         case WDIOC_SETTIMEOUT:
 133                 ret = get_user(time, (int *)arg);
 134                 if (ret)
 135                         break;
 136
 137                 if (time <= 0 || time > 60) {
 138                         ret = -EINVAL;
 139                         break;
 140                 }
 141
 142                 heartbeat = time;
 143                 wdt_keepalive();
 144                 /* Fall through */
 145
 146         case WDIOC_GETTIMEOUT:
 147                 ret = put_user(heartbeat, (int *)arg);
 148                 break;
 149
 150         case WDIOC_KEEPALIVE:
 151                 wdt_enable();
 152                 ret = 0;
 153                 break;
 154         }
 155
 156         return ret;
 157 }
 158
 159 static int
 160 ixp2000_wdt_release(struct inode *inode, struct file *file)
 161 {
 162         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
 163                 wdt_disable();
 164         } else {
 165                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectdly - "
 166                                         "timer will not stop\n");
 167         }
 168
 169         clear_bit(WDT_IN_USE, &wdt_status);
 170         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 171
 172         return 0;
 173 }
 174
 175
 176 static struct file_operations ixp2000_wdt_fops =
 177 {
 178         .owner          = THIS_MODULE,
 179         .llseek         = no_llseek,
 180         .write          = ixp2000_wdt_write,
 181         .ioctl          = ixp2000_wdt_ioctl,
 182         .open           = ixp2000_wdt_open,
 183         .release        = ixp2000_wdt_release,
 184 };
 185
 186 static struct miscdevice ixp2000_wdt_miscdev =
 187 {
 188         .minor          = WATCHDOG_MINOR,
 189         .name           = "IXP2000 Watchdog",
 190         .fops           = &ixp2000_wdt_fops,
 191 };
 192
 193 static int __init ixp2000_wdt_init(void)
 194 {
 195         wdt_tick_rate = (*IXP2000_T1_CLD * HZ)/ 256;;
 196
 197         return misc_register(&ixp2000_wdt_miscdev);
 198 }
 199
 200 static void __exit ixp2000_wdt_exit(void)
 201 {
 202         misc_deregister(&ixp2000_wdt_miscdev);
 203 }
 204
 205 module_init(ixp2000_wdt_init);
 206 module_exit(ixp2000_wdt_exit);
 207
 208 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net">);
 209 MODULE_DESCRIPTION("IXP2000 Network Processor Watchdog");
 210
 211 module_param(heartbeat, int, 0);
 212 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 213
 214 module_param(nowayout, int, 0);
 215 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 216
 217 MODULE_LICENSE("GPL");
 218 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 219