drivers/char/watchdog/ixp4xx_wdt.c

   1 /*
   2  * drivers/watchdog/ixp4xx_wdt.c
   3  *
   4  * Watchdog driver for Intel IXP4xx network processors
   5  *
   6  * Author: Deepak Saxena <dsaxena@plexity.net>
   7  *
   8  * Copyright 2004 (c) MontaVista, Software, Inc.
   9  * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  10  *
  11  * This file is licensed under  the terms of the GNU General Public
  12  * License version 2. This program is licensed "as is" without any
  13  * warranty of any kind, whether express or implied.
  14  */
  15
  16 #include <linux/config.h>
  17 #include <linux/module.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/types.h>
  20 #include <linux/kernel.h>
  21 #include <linux/fs.h>
  22 #include <linux/miscdevice.h>
  23 #include <linux/watchdog.h>
  24 #include <linux/init.h>
  25 #include <linux/bitops.h>
  26
  27 #include <asm/hardware.h>
  28 #include <asm/uaccess.h>
  29
  30 static int nowayout = WATCHDOG_NOWAYOUT;
  31 static int heartbeat = 60;      /* (secs) Default is 1 minute */
  32 static unsigned long wdt_status;
  33 static unsigned long boot_status;
  34
  35 #define WDT_TICK_RATE (IXP4XX_PERIPHERAL_BUS_CLOCK * 1000000UL)
  36
  37 #define WDT_IN_USE              0
  38 #define WDT_OK_TO_CLOSE         1
  39
  40 static void
  41 wdt_enable(void)
  42 {
  43         *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  44         *IXP4XX_OSWE = 0;
  45         *IXP4XX_OSWT = WDT_TICK_RATE * heartbeat;
  46         *IXP4XX_OSWE = IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE;
  47         *IXP4XX_OSWK = 0;
  48 }
  49
  50 static void
  51 wdt_disable(void)
  52 {
  53         *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  54         *IXP4XX_OSWE = 0;
  55         *IXP4XX_OSWK = 0;
  56 }
  57
  58 static int
  59 ixp4xx_wdt_open(struct inode *inode, struct file *file)
  60 {
  61         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  62                 return -EBUSY;
  63
  64         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  65
  66         wdt_enable();
  67
  68         return nonseekable_open(inode, file);
  69 }
  70
  71 static ssize_t
  72 ixp4xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  73 {
  74         if (len) {
  75                 if (!nowayout) {
  76                         size_t i;
  77
  78                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  79
  80                         for (i = 0; i != len; i++) {
  81                                 char c;
  82
  83                                 if (get_user(c, data + i))
  84                                         return -EFAULT;
  85                                 if (c == 'V')
  86                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  87                         }
  88                 }
  89                 wdt_enable();
  90         }
  91
  92         return len;
  93 }
  94
  95 static struct watchdog_info ident = {
  96         .options        = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
  97                           WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  98         .identity       = "IXP4xx Watchdog",
  99 };
 100
 101
 102 static int
 103 ixp4xx_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 104                         unsigned long arg)
 105 {
 106         int ret = -ENOIOCTLCMD;
 107         int time;
 108
 109         switch (cmd) {
 110         case WDIOC_GETSUPPORT:
 111                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 112                                    sizeof(ident)) ? -EFAULT : 0;
 113                 break;
 114
 115         case WDIOC_GETSTATUS:
 116                 ret = put_user(0, (int *)arg);
 117                 break;
 118
 119         case WDIOC_GETBOOTSTATUS:
 120                 ret = put_user(boot_status, (int *)arg);
 121                 break;
 122
 123         case WDIOC_SETTIMEOUT:
 124                 ret = get_user(time, (int *)arg);
 125                 if (ret)
 126                         break;
 127
 128                 if (time <= 0 || time > 60) {
 129                         ret = -EINVAL;
 130                         break;
 131                 }
 132
 133                 heartbeat = time;
 134                 wdt_enable();
 135                 /* Fall through */
 136
 137         case WDIOC_GETTIMEOUT:
 138                 ret = put_user(heartbeat, (int *)arg);
 139                 break;
 140
 141         case WDIOC_KEEPALIVE:
 142                 wdt_enable();
 143                 ret = 0;
 144                 break;
 145         }
 146         return ret;
 147 }
 148
 149 static int
 150 ixp4xx_wdt_release(struct inode *inode, struct file *file)
 151 {
 152         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
 153                 wdt_disable();
 154         } else {
 155                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
 156                                         "timer will not stop\n");
 157         }
 158
 159         clear_bit(WDT_IN_USE, &wdt_status);
 160         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 161
 162         return 0;
 163 }
 164
 165
 166 static struct file_operations ixp4xx_wdt_fops =
 167 {
 168         .owner          = THIS_MODULE,
 169         .llseek         = no_llseek,
 170         .write          = ixp4xx_wdt_write,
 171         .ioctl          = ixp4xx_wdt_ioctl,
 172         .open           = ixp4xx_wdt_open,
 173         .release        = ixp4xx_wdt_release,
 174 };
 175
 176 static struct miscdevice ixp4xx_wdt_miscdev =
 177 {
 178         .minor          = WATCHDOG_MINOR,
 179         .name           = "watchdog",
 180         .fops           = &ixp4xx_wdt_fops,
 181 };
 182
 183 static int __init ixp4xx_wdt_init(void)
 184 {
 185         int ret;
 186         unsigned long processor_id;
 187
 188         asm("mrc p15, 0, %0, cr0, cr0, 0;" : "=r"(processor_id) :);
 189         if (!(processor_id & 0xf) && !cpu_is_ixp46x()) {
 190                 printk("IXP4XXX Watchdog: Rev. A0 IXP42x CPU detected - "
 191                         "watchdog disabled\n");
 192
 193                 return -ENODEV;
 194         }
 195
 196         ret = misc_register(&ixp4xx_wdt_miscdev);
 197         if (ret == 0)
 198                 printk("IXP4xx Watchdog Timer: heartbeat %d sec\n", heartbeat);
 199
 200         boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ?
 201                         WDIOF_CARDRESET : 0;
 202
 203         return ret;
 204 }
 205
 206 static void __exit ixp4xx_wdt_exit(void)
 207 {
 208         misc_deregister(&ixp4xx_wdt_miscdev);
 209 }
 210
 211
 212 module_init(ixp4xx_wdt_init);
 213 module_exit(ixp4xx_wdt_exit);
 214
 215 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 216 MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
 217
 218 module_param(heartbeat, int, 0);
 219 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 220
 221 module_param(nowayout, int, 0);
 222 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 223
 224 MODULE_LICENSE("GPL");
 225 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 226