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   1 /*
   2  * drivers/char/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/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/types.h>
  19 #include <linux/kernel.h>
  20 #include <linux/fs.h>
  21 #include <linux/miscdevice.h>
  22 #include <linux/watchdog.h>
  23 #include <linux/init.h>
  24 #include <linux/bitops.h>
  25 #include <linux/uaccess.h>
  26 #include <mach/hardware.h>
  27
  28 static int nowayout = WATCHDOG_NOWAYOUT;
  29 static int heartbeat = 60;      /* (secs) Default is 1 minute */
  30 static unsigned long wdt_status;
  31 static unsigned long boot_status;
  32 static DEFINE_SPINLOCK(wdt_lock);
  33
  34 #define WDT_TICK_RATE (IXP4XX_PERIPHERAL_BUS_CLOCK * 1000000UL)
  35
  36 #define WDT_IN_USE              0
  37 #define WDT_OK_TO_CLOSE         1
  38
  39 static void wdt_enable(void)
  40 {
  41         spin_lock(&wdt_lock);
  42         *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  43         *IXP4XX_OSWE = 0;
  44         *IXP4XX_OSWT = WDT_TICK_RATE * heartbeat;
  45         *IXP4XX_OSWE = IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE;
  46         *IXP4XX_OSWK = 0;
  47         spin_unlock(&wdt_lock);
  48 }
  49
  50 static void wdt_disable(void)
  51 {
  52         spin_lock(&wdt_lock);
  53         *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  54         *IXP4XX_OSWE = 0;
  55         *IXP4XX_OSWK = 0;
  56         spin_unlock(&wdt_lock);
  57 }
  58
  59 static int 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         wdt_enable();
  66         return nonseekable_open(inode, file);
  67 }
  68
  69 static ssize_t
  70 ixp4xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  71 {
  72         if (len) {
  73                 if (!nowayout) {
  74                         size_t i;
  75
  76                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  77
  78                         for (i = 0; i != len; i++) {
  79                                 char c;
  80
  81                                 if (get_user(c, data + i))
  82                                         return -EFAULT;
  83                                 if (c == 'V')
  84                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  85                         }
  86                 }
  87                 wdt_enable();
  88         }
  89         return len;
  90 }
  91
  92 static struct watchdog_info ident = {
  93         .options        = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
  94                           WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  95         .identity       = "IXP4xx Watchdog",
  96 };
  97
  98
  99 static long ixp4xx_wdt_ioctl(struct file *file, unsigned int cmd,
 100                                                         unsigned long arg)
 101 {
 102         int ret = -ENOTTY;
 103         int time;
 104
 105         switch (cmd) {
 106         case WDIOC_GETSUPPORT:
 107                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 108                                    sizeof(ident)) ? -EFAULT : 0;
 109                 break;
 110
 111         case WDIOC_GETSTATUS:
 112                 ret = put_user(0, (int *)arg);
 113                 break;
 114
 115         case WDIOC_GETBOOTSTATUS:
 116                 ret = put_user(boot_status, (int *)arg);
 117                 break;
 118
 119         case WDIOC_KEEPALIVE:
 120                 wdt_enable();
 121                 ret = 0;
 122                 break;
 123
 124         case WDIOC_SETTIMEOUT:
 125                 ret = get_user(time, (int *)arg);
 126                 if (ret)
 127                         break;
 128
 129                 if (time <= 0 || time > 60) {
 130                         ret = -EINVAL;
 131                         break;
 132                 }
 133
 134                 heartbeat = time;
 135                 wdt_enable();
 136                 /* Fall through */
 137
 138         case WDIOC_GETTIMEOUT:
 139                 ret = put_user(heartbeat, (int *)arg);
 140                 break;
 141         }
 142         return ret;
 143 }
 144
 145 static int ixp4xx_wdt_release(struct inode *inode, struct file *file)
 146 {
 147         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 148                 wdt_disable();
 149         else
 150                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
 151                                         "timer will not stop\n");
 152         clear_bit(WDT_IN_USE, &wdt_status);
 153         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 154
 155         return 0;
 156 }
 157
 158
 159 static const struct file_operations ixp4xx_wdt_fops = {
 160         .owner          = THIS_MODULE,
 161         .llseek         = no_llseek,
 162         .write          = ixp4xx_wdt_write,
 163         .unlocked_ioctl = ixp4xx_wdt_ioctl,
 164         .open           = ixp4xx_wdt_open,
 165         .release        = ixp4xx_wdt_release,
 166 };
 167
 168 static struct miscdevice ixp4xx_wdt_miscdev = {
 169         .minor          = WATCHDOG_MINOR,
 170         .name           = "watchdog",
 171         .fops           = &ixp4xx_wdt_fops,
 172 };
 173
 174 static int __init ixp4xx_wdt_init(void)
 175 {
 176         int ret;
 177         unsigned long processor_id;
 178
 179         asm("mrc p15, 0, %0, cr0, cr0, 0;" : "=r"(processor_id) :);
 180         if (!(processor_id & 0xf) && !cpu_is_ixp46x()) {
 181                 printk(KERN_ERR "IXP4XXX Watchdog: Rev. A0 IXP42x CPU detected"
 182                         " - watchdog disabled\n");
 183
 184                 return -ENODEV;
 185         }
 186         spin_lock_init(&wdt_lock);
 187         boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ?
 188                         WDIOF_CARDRESET : 0;
 189         ret = misc_register(&ixp4xx_wdt_miscdev);
 190         if (ret == 0)
 191                 printk(KERN_INFO "IXP4xx Watchdog Timer: heartbeat %d sec\n",
 192                         heartbeat);
 193         return ret;
 194 }
 195
 196 static void __exit ixp4xx_wdt_exit(void)
 197 {
 198         misc_deregister(&ixp4xx_wdt_miscdev);
 199 }
 200
 201
 202 module_init(ixp4xx_wdt_init);
 203 module_exit(ixp4xx_wdt_exit);
 204
 205 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 206 MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
 207
 208 module_param(heartbeat, int, 0);
 209 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 210
 211 module_param(nowayout, int, 0);
 212 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 213
 214 MODULE_LICENSE("GPL");
 215 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 216