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 static int nowayout = WATCHDOG_NOWAYOUT;
  34 static unsigned int heartbeat = 60;     /* (secs) Default is 1 minute */
  35 static unsigned long wdt_status;
  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
  43 wdt_enable(void)
  44 {
  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 }
  50
  51 static void
  52 wdt_disable(void)
  53 {
  54         ixp2000_reg_write(IXP2000_T4_CTL, 0);
  55 }
  56
  57 static void
  58 wdt_keepalive(void)
  59 {
  60         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
  61 }
  62
  63 static int
  64 ixp2000_wdt_open(struct inode *inode, struct file *file)
  65 {
  66         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  67                 return -EBUSY;
  68
  69         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  70
  71         wdt_enable();
  72
  73         return nonseekable_open(inode, file);
  74 }
  75
  76 static ssize_t
  77 ixp2000_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  78 {
  79         if (len) {
  80                 if (!nowayout) {
  81                         size_t i;
  82
  83                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  84
  85                         for (i = 0; i != len; i++) {
  86                                 char c;
  87
  88                                 if (get_user(c, data + i))
  89                                         return -EFAULT;
  90                                 if (c == 'V')
  91                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  92                         }
  93                 }
  94                 wdt_keepalive();
  95         }
  96
  97         return len;
  98 }
  99
 100
 101 static struct watchdog_info ident = {
 102         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 103                                 WDIOF_KEEPALIVEPING,
 104         .identity       = "IXP2000 Watchdog",
 105 };
 106
 107 static int
 108 ixp2000_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 109                         unsigned long arg)
 110 {
 111         int ret = -ENOIOCTLCMD;
 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_SETTIMEOUT:
 129                 ret = get_user(time, (int *)arg);
 130                 if (ret)
 131                         break;
 132
 133                 if (time <= 0 || time > 60) {
 134                         ret = -EINVAL;
 135                         break;
 136                 }
 137
 138                 heartbeat = time;
 139                 wdt_keepalive();
 140                 /* Fall through */
 141
 142         case WDIOC_GETTIMEOUT:
 143                 ret = put_user(heartbeat, (int *)arg);
 144                 break;
 145
 146         case WDIOC_KEEPALIVE:
 147                 wdt_enable();
 148                 ret = 0;
 149                 break;
 150         }
 151
 152         return ret;
 153 }
 154
 155 static int
 156 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         }
 164
 165         clear_bit(WDT_IN_USE, &wdt_status);
 166         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 167
 168         return 0;
 169 }
 170
 171
 172 static struct file_operations ixp2000_wdt_fops =
 173 {
 174         .owner          = THIS_MODULE,
 175         .llseek         = no_llseek,
 176         .write          = ixp2000_wdt_write,
 177         .ioctl          = ixp2000_wdt_ioctl,
 178         .open           = ixp2000_wdt_open,
 179         .release        = ixp2000_wdt_release,
 180 };
 181
 182 static struct miscdevice ixp2000_wdt_miscdev =
 183 {
 184         .minor          = WATCHDOG_MINOR,
 185         .name           = "watchdog",
 186         .fops           = &ixp2000_wdt_fops,
 187 };
 188
 189 static int __init ixp2000_wdt_init(void)
 190 {
 191         if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
 192                 printk(KERN_INFO "Unable to use IXP2000 watchdog due to IXP2800 erratum #25.\n");
 193                 return -EIO;
 194         }
 195
 196         wdt_tick_rate = (*IXP2000_T1_CLD * HZ) / 256;
 197
 198         return misc_register(&ixp2000_wdt_miscdev);
 199 }
 200
 201 static void __exit ixp2000_wdt_exit(void)
 202 {
 203         misc_deregister(&ixp2000_wdt_miscdev);
 204 }
 205
 206 module_init(ixp2000_wdt_init);
 207 module_exit(ixp2000_wdt_exit);
 208
 209 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net">);
 210 MODULE_DESCRIPTION("IXP2000 Network Processor Watchdog");
 211
 212 module_param(heartbeat, int, 0);
 213 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 214
 215 module_param(nowayout, int, 0);
 216 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 217
 218 MODULE_LICENSE("GPL");
 219 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 220