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   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 #include <linux/uaccess.h>
  29 #include <mach/hardware.h>
  30
  31 static int nowayout = WATCHDOG_NOWAYOUT;
  32 static unsigned int heartbeat = 60;     /* (secs) Default is 1 minute */
  33 static unsigned long wdt_status;
  34 static spinlock_t wdt_lock;
  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 wdt_enable(void)
  42 {
  43         spin_lock(&wdt_lock);
  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         spin_unlock(&wdt_lock);
  49 }
  50
  51 static void wdt_disable(void)
  52 {
  53         spin_lock(&wdt_lock);
  54         ixp2000_reg_write(IXP2000_T4_CTL, 0);
  55         spin_unlock(&wdt_lock);
  56 }
  57
  58 static void wdt_keepalive(void)
  59 {
  60         spin_lock(&wdt_lock);
  61         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
  62         spin_unlock(&wdt_lock);
  63 }
  64
  65 static int ixp2000_wdt_open(struct inode *inode, struct file *file)
  66 {
  67         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  68                 return -EBUSY;
  69
  70         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  71
  72         wdt_enable();
  73
  74         return nonseekable_open(inode, file);
  75 }
  76
  77 static ssize_t ixp2000_wdt_write(struct file *file, const char *data,
  78                                                 size_t len, loff_t *ppos)
  79 {
  80         if (len) {
  81                 if (!nowayout) {
  82                         size_t i;
  83
  84                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  85
  86                         for (i = 0; i != len; i++) {
  87                                 char c;
  88
  89                                 if (get_user(c, data + i))
  90                                         return -EFAULT;
  91                                 if (c == 'V')
  92                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  93                         }
  94                 }
  95                 wdt_keepalive();
  96         }
  97
  98         return len;
  99 }
 100
 101
 102 static struct watchdog_info ident = {
 103         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 104                                 WDIOF_KEEPALIVEPING,
 105         .identity       = "IXP2000 Watchdog",
 106 };
 107
 108 static long ixp2000_wdt_ioctl(struct file *file, unsigned int cmd,
 109                                                         unsigned long arg)
 110 {
 111         int ret = -ENOTTY;
 112         int time;
 113
 114         switch (cmd) {
 115         case WDIOC_GETSUPPORT:
 116                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 117                                    sizeof(ident)) ? -EFAULT : 0;
 118                 break;
 119
 120         case WDIOC_GETSTATUS:
 121                 ret = put_user(0, (int *)arg);
 122                 break;
 123
 124         case WDIOC_GETBOOTSTATUS:
 125                 ret = put_user(0, (int *)arg);
 126                 break;
 127
 128         case WDIOC_KEEPALIVE:
 129                 wdt_enable();
 130                 ret = 0;
 131                 break;
 132
 133         case WDIOC_SETTIMEOUT:
 134                 ret = get_user(time, (int *)arg);
 135                 if (ret)
 136                         break;
 137
 138                 if (time <= 0 || time > 60) {
 139                         ret = -EINVAL;
 140                         break;
 141                 }
 142
 143                 heartbeat = time;
 144                 wdt_keepalive();
 145                 /* Fall through */
 146
 147         case WDIOC_GETTIMEOUT:
 148                 ret = put_user(heartbeat, (int *)arg);
 149                 break;
 150         }
 151
 152         return ret;
 153 }
 154
 155 static int 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         clear_bit(WDT_IN_USE, &wdt_status);
 163         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 164
 165         return 0;
 166 }
 167
 168
 169 static const struct file_operations ixp2000_wdt_fops = {
 170         .owner          = THIS_MODULE,
 171         .llseek         = no_llseek,
 172         .write          = ixp2000_wdt_write,
 173         .unlocked_ioctl = ixp2000_wdt_ioctl,
 174         .open           = ixp2000_wdt_open,
 175         .release        = ixp2000_wdt_release,
 176 };
 177
 178 static struct miscdevice ixp2000_wdt_miscdev = {
 179         .minor          = WATCHDOG_MINOR,
 180         .name           = "watchdog",
 181         .fops           = &ixp2000_wdt_fops,
 182 };
 183
 184 static int __init ixp2000_wdt_init(void)
 185 {
 186         if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
 187                 printk(KERN_INFO "Unable to use IXP2000 watchdog due to IXP2800 erratum #25.\n");
 188                 return -EIO;
 189         }
 190         wdt_tick_rate = (*IXP2000_T1_CLD * HZ) / 256;
 191         spin_lock_init(&wdt_lock);
 192         return misc_register(&ixp2000_wdt_miscdev);
 193 }
 194
 195 static void __exit ixp2000_wdt_exit(void)
 196 {
 197         misc_deregister(&ixp2000_wdt_miscdev);
 198 }
 199
 200 module_init(ixp2000_wdt_init);
 201 module_exit(ixp2000_wdt_exit);
 202
 203 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 204 MODULE_DESCRIPTION("IXP2000 Network Processor Watchdog");
 205
 206 module_param(heartbeat, int, 0);
 207 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 208
 209 module_param(nowayout, int, 0);
 210 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 211
 212 MODULE_LICENSE("GPL");
 213 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 214