release/src-rt-6.x.4708/linux/linux-2.6.36/drivers/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/timer.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 #include <linux/uaccess.h>
  30 #include <mach/hardware.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 static spinlock_t wdt_lock;
  36
  37 #define WDT_IN_USE              0
  38 #define WDT_OK_TO_CLOSE         1
  39
  40 static unsigned long wdt_tick_rate;
  41
  42 static void wdt_enable(void)
  43 {
  44         spin_lock(&wdt_lock);
  45         ixp2000_reg_write(IXP2000_RESET0, *(IXP2000_RESET0) | WDT_RESET_ENABLE);
  46         ixp2000_reg_write(IXP2000_TWDE, WDT_ENABLE);
  47         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
  48         ixp2000_reg_write(IXP2000_T4_CTL, TIMER_DIVIDER_256 | TIMER_ENABLE);
  49         spin_unlock(&wdt_lock);
  50 }
  51
  52 static void wdt_disable(void)
  53 {
  54         spin_lock(&wdt_lock);
  55         ixp2000_reg_write(IXP2000_T4_CTL, 0);
  56         spin_unlock(&wdt_lock);
  57 }
  58
  59 static void wdt_keepalive(void)
  60 {
  61         spin_lock(&wdt_lock);
  62         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
  63         spin_unlock(&wdt_lock);
  64 }
  65
  66 static int ixp2000_wdt_open(struct inode *inode, struct file *file)
  67 {
  68         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  69                 return -EBUSY;
  70
  71         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  72
  73         wdt_enable();
  74
  75         return nonseekable_open(inode, file);
  76 }
  77
  78 static ssize_t ixp2000_wdt_write(struct file *file, const char *data,
  79                                                 size_t len, loff_t *ppos)
  80 {
  81         if (len) {
  82                 if (!nowayout) {
  83                         size_t i;
  84
  85                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  86
  87                         for (i = 0; i != len; i++) {
  88                                 char c;
  89
  90                                 if (get_user(c, data + i))
  91                                         return -EFAULT;
  92                                 if (c == 'V')
  93                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  94                         }
  95                 }
  96                 wdt_keepalive();
  97         }
  98
  99         return len;
 100 }
 101
 102
 103 static const struct watchdog_info ident = {
 104         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 105                                 WDIOF_KEEPALIVEPING,
 106         .identity       = "IXP2000 Watchdog",
 107 };
 108
 109 static long ixp2000_wdt_ioctl(struct file *file, unsigned int cmd,
 110                                                         unsigned long arg)
 111 {
 112         int ret = -ENOTTY;
 113         int time;
 114
 115         switch (cmd) {
 116         case WDIOC_GETSUPPORT:
 117                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 118                                    sizeof(ident)) ? -EFAULT : 0;
 119                 break;
 120
 121         case WDIOC_GETSTATUS:
 122                 ret = put_user(0, (int *)arg);
 123                 break;
 124
 125         case WDIOC_GETBOOTSTATUS:
 126                 ret = put_user(0, (int *)arg);
 127                 break;
 128
 129         case WDIOC_KEEPALIVE:
 130                 wdt_enable();
 131                 ret = 0;
 132                 break;
 133
 134         case WDIOC_SETTIMEOUT:
 135                 ret = get_user(time, (int *)arg);
 136                 if (ret)
 137                         break;
 138
 139                 if (time <= 0 || time > 60) {
 140                         ret = -EINVAL;
 141                         break;
 142                 }
 143
 144                 heartbeat = time;
 145                 wdt_keepalive();
 146                 /* Fall through */
 147
 148         case WDIOC_GETTIMEOUT:
 149                 ret = put_user(heartbeat, (int *)arg);
 150                 break;
 151         }
 152
 153         return ret;
 154 }
 155
 156 static int ixp2000_wdt_release(struct inode *inode, struct file *file)
 157 {
 158         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 159                 wdt_disable();
 160         else
 161                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
 162                                         "timer will not stop\n");
 163         clear_bit(WDT_IN_USE, &wdt_status);
 164         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 165
 166         return 0;
 167 }
 168
 169
 170 static const struct file_operations ixp2000_wdt_fops = {
 171         .owner          = THIS_MODULE,
 172         .llseek         = no_llseek,
 173         .write          = ixp2000_wdt_write,
 174         .unlocked_ioctl = ixp2000_wdt_ioctl,
 175         .open           = ixp2000_wdt_open,
 176         .release        = ixp2000_wdt_release,
 177 };
 178
 179 static struct miscdevice ixp2000_wdt_miscdev = {
 180         .minor          = WATCHDOG_MINOR,
 181         .name           = "watchdog",
 182         .fops           = &ixp2000_wdt_fops,
 183 };
 184
 185 static int __init ixp2000_wdt_init(void)
 186 {
 187         if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
 188                 printk(KERN_INFO "Unable to use IXP2000 watchdog due to IXP2800 erratum #25.\n");
 189                 return -EIO;
 190         }
 191         wdt_tick_rate = (*IXP2000_T1_CLD * HZ) / 256;
 192         spin_lock_init(&wdt_lock);
 193         return misc_register(&ixp2000_wdt_miscdev);
 194 }
 195
 196 static void __exit ixp2000_wdt_exit(void)
 197 {
 198         misc_deregister(&ixp2000_wdt_miscdev);
 199 }
 200
 201 module_init(ixp2000_wdt_init);
 202 module_exit(ixp2000_wdt_exit);
 203
 204 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 205 MODULE_DESCRIPTION("IXP2000 Network Processor Watchdog");
 206
 207 module_param(heartbeat, int, 0);
 208 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 209
 210 module_param(nowayout, int, 0);
 211 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 212
 213 MODULE_LICENSE("GPL");
 214 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);