drivers/char/watchdog/ixp2000_wdt.c

   1 /*
   2  * drivers/char/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/module.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/types.h>
  22 #include <linux/kernel.h>
  23 #include <linux/fs.h>
  24 #include <linux/miscdevice.h>
  25 #include <linux/watchdog.h>
  26 #include <linux/init.h>
  27 #include <linux/bitops.h>
  28
  29 #include <asm/hardware.h>
  30 #include <asm/uaccess.h>
  31
  32 static int nowayout = WATCHDOG_NOWAYOUT;
  33 static unsigned int heartbeat = 60;     /* (secs) Default is 1 minute */
  34 static unsigned long wdt_status;
  35
  36 #define WDT_IN_USE              0
  37 #define WDT_OK_TO_CLOSE         1
  38
  39 static unsigned long wdt_tick_rate;
  40
  41 static void
  42 wdt_enable(void)
  43 {
  44         ixp2000_reg_write(IXP2000_RESET0, *(IXP2000_RESET0) | WDT_RESET_ENABLE);
  45         ixp2000_reg_write(IXP2000_TWDE, WDT_ENABLE);
  46         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
  47         ixp2000_reg_write(IXP2000_T4_CTL, TIMER_DIVIDER_256 | TIMER_ENABLE);
  48 }
  49
  50 static void
  51 wdt_disable(void)
  52 {
  53         ixp2000_reg_write(IXP2000_T4_CTL, 0);
  54 }
  55
  56 static void
  57 wdt_keepalive(void)
  58 {
  59         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
  60 }
  61
  62 static int
  63 ixp2000_wdt_open(struct inode *inode, struct file *file)
  64 {
  65         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  66                 return -EBUSY;
  67
  68         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  69
  70         wdt_enable();
  71
  72         return nonseekable_open(inode, file);
  73 }
  74
  75 static ssize_t
  76 ixp2000_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  77 {
  78         if (len) {
  79                 if (!nowayout) {
  80                         size_t i;
  81
  82                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  83
  84                         for (i = 0; i != len; i++) {
  85                                 char c;
  86
  87                                 if (get_user(c, data + i))
  88                                         return -EFAULT;
  89                                 if (c == 'V')
  90                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  91                         }
  92                 }
  93                 wdt_keepalive();
  94         }
  95
  96         return len;
  97 }
  98
  99
 100 static struct watchdog_info ident = {
 101         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 102                                 WDIOF_KEEPALIVEPING,
 103         .identity       = "IXP2000 Watchdog",
 104 };
 105
 106 static int
 107 ixp2000_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 108                         unsigned long arg)
 109 {
 110         int ret = -ENOTTY;
 111         int time;
 112
 113         switch (cmd) {
 114         case WDIOC_GETSUPPORT:
 115                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 116                                    sizeof(ident)) ? -EFAULT : 0;
 117                 break;
 118
 119         case WDIOC_GETSTATUS:
 120                 ret = put_user(0, (int *)arg);
 121                 break;
 122
 123         case WDIOC_GETBOOTSTATUS:
 124                 ret = put_user(0, (int *)arg);
 125                 break;
 126
 127         case WDIOC_SETTIMEOUT:
 128                 ret = get_user(time, (int *)arg);
 129                 if (ret)
 130                         break;
 131
 132                 if (time <= 0 || time > 60) {
 133                         ret = -EINVAL;
 134                         break;
 135                 }
 136
 137                 heartbeat = time;
 138                 wdt_keepalive();
 139                 /* Fall through */
 140
 141         case WDIOC_GETTIMEOUT:
 142                 ret = put_user(heartbeat, (int *)arg);
 143                 break;
 144
 145         case WDIOC_KEEPALIVE:
 146                 wdt_enable();
 147                 ret = 0;
 148                 break;
 149         }
 150
 151         return ret;
 152 }
 153
 154 static int
 155 ixp2000_wdt_release(struct inode *inode, struct file *file)
 156 {
 157         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
 158                 wdt_disable();
 159         } else {
 160                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
 161                                         "timer will not stop\n");
 162         }
 163
 164         clear_bit(WDT_IN_USE, &wdt_status);
 165         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 166
 167         return 0;
 168 }
 169
 170
 171 static const struct file_operations ixp2000_wdt_fops =
 172 {
 173         .owner          = THIS_MODULE,
 174         .llseek         = no_llseek,
 175         .write          = ixp2000_wdt_write,
 176         .ioctl          = ixp2000_wdt_ioctl,
 177         .open           = ixp2000_wdt_open,
 178         .release        = ixp2000_wdt_release,
 179 };
 180
 181 static struct miscdevice ixp2000_wdt_miscdev =
 182 {
 183         .minor          = WATCHDOG_MINOR,
 184         .name           = "watchdog",
 185         .fops           = &ixp2000_wdt_fops,
 186 };
 187
 188 static int __init ixp2000_wdt_init(void)
 189 {
 190         if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
 191                 printk(KERN_INFO "Unable to use IXP2000 watchdog due to IXP2800 erratum #25.\n");
 192                 return -EIO;
 193         }
 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