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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
  27 #include <asm/hardware.h>
  28
  29 static int nowayout = WATCHDOG_NOWAYOUT;
  30 static int heartbeat = 60;      /* (secs) Default is 1 minute */
  31 static unsigned long wdt_status;
  32 static unsigned long boot_status;
  33 static spin_lock_t wdt_lock;
  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 wdt_enable(void)
  41 {
  42         spin_lock(&wdt_lock);
  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         spin_unlock(&wdt_lock);
  49 }
  50
  51 static void wdt_disable(void)
  52 {
  53         spin_lock(&wdt_lock);
  54         *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  55         *IXP4XX_OSWE = 0;
  56         *IXP4XX_OSWK = 0;
  57         spin_unlock(&wdt_lock);
  58 }
  59
  60 static int ixp4xx_wdt_open(struct inode *inode, struct file *file)
  61 {
  62         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  63                 return -EBUSY;
  64
  65         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  66         wdt_enable();
  67         return nonseekable_open(inode, file);
  68 }
  69
  70 static ssize_t
  71 ixp4xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  72 {
  73         if (len) {
  74                 if (!nowayout) {
  75                         size_t i;
  76
  77                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  78
  79                         for (i = 0; i != len; i++) {
  80                                 char c;
  81
  82                                 if (get_user(c, data + i))
  83                                         return -EFAULT;
  84                                 if (c == 'V')
  85                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  86                         }
  87                 }
  88                 wdt_enable();
  89         }
  90         return len;
  91 }
  92
  93 static struct watchdog_info ident = {
  94         .options        = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
  95                           WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  96         .identity       = "IXP4xx Watchdog",
  97 };
  98
  99
 100 static long ixp4xx_wdt_ioctl(struct file *file, unsigned int cmd,
 101                                                         unsigned long arg)
 102 {
 103         int ret = -ENOTTY;
 104         int time;
 105
 106         switch (cmd) {
 107         case WDIOC_GETSUPPORT:
 108                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 109                                    sizeof(ident)) ? -EFAULT : 0;
 110                 break;
 111
 112         case WDIOC_GETSTATUS:
 113                 ret = put_user(0, (int *)arg);
 114                 break;
 115
 116         case WDIOC_GETBOOTSTATUS:
 117                 ret = put_user(boot_status, (int *)arg);
 118                 break;
 119
 120         case WDIOC_SETTIMEOUT:
 121                 ret = get_user(time, (int *)arg);
 122                 if (ret)
 123                         break;
 124
 125                 if (time <= 0 || time > 60) {
 126                         ret = -EINVAL;
 127                         break;
 128                 }
 129
 130                 heartbeat = time;
 131                 wdt_enable();
 132                 /* Fall through */
 133
 134         case WDIOC_GETTIMEOUT:
 135                 ret = put_user(heartbeat, (int *)arg);
 136                 break;
 137
 138         case WDIOC_KEEPALIVE:
 139                 wdt_enable();
 140                 ret = 0;
 141                 break;
 142         }
 143         return ret;
 144 }
 145
 146 static int ixp4xx_wdt_release(struct inode *inode, struct file *file)
 147 {
 148         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 149                 wdt_disable();
 150         else
 151                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
 152                                         "timer will not stop\n");
 153         clear_bit(WDT_IN_USE, &wdt_status);
 154         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 155
 156         return 0;
 157 }
 158
 159
 160 static const struct file_operations ixp4xx_wdt_fops =
 161 {
 162         .owner          = THIS_MODULE,
 163         .llseek         = no_llseek,
 164         .write          = ixp4xx_wdt_write,
 165         .unlocked_ioctl = ixp4xx_wdt_ioctl,
 166         .open           = ixp4xx_wdt_open,
 167         .release        = ixp4xx_wdt_release,
 168 };
 169
 170 static struct miscdevice ixp4xx_wdt_miscdev =
 171 {
 172         .minor          = WATCHDOG_MINOR,
 173         .name           = "watchdog",
 174         .fops           = &ixp4xx_wdt_fops,
 175 };
 176
 177 static int __init ixp4xx_wdt_init(void)
 178 {
 179         int ret;
 180         unsigned long processor_id;
 181
 182         asm("mrc p15, 0, %0, cr0, cr0, 0;" : "=r"(processor_id) :);
 183         if (!(processor_id & 0xf) && !cpu_is_ixp46x()) {
 184                 printk("IXP4XXX Watchdog: Rev. A0 IXP42x CPU detected - "
 185                         "watchdog disabled\n");
 186
 187                 return -ENODEV;
 188         }
 189         spin_lock_init(&wdt_lock);
 190         boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ?
 191                         WDIOF_CARDRESET : 0;
 192         ret = misc_register(&ixp4xx_wdt_miscdev);
 193         if (ret == 0)
 194                 printk("IXP4xx Watchdog Timer: heartbeat %d sec\n", heartbeat);
 195         return ret;
 196 }
 197
 198 static void __exit ixp4xx_wdt_exit(void)
 199 {
 200         misc_deregister(&ixp4xx_wdt_miscdev);
 201 }
 202
 203
 204 module_init(ixp4xx_wdt_init);
 205 module_exit(ixp4xx_wdt_exit);
 206
 207 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 208 MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
 209
 210 module_param(heartbeat, int, 0);
 211 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 212
 213 module_param(nowayout, int, 0);
 214 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 215
 216 MODULE_LICENSE("GPL");
 217 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 218