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
  26 #include <asm/hardware.h>
  27 #include <asm/bitops.h>
  28 #include <asm/uaccess.h>
  29
  30 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  31 static int nowayout = 1;
  32 #else
  33 static int nowayout = 0;
  34 #endif
  35 static int heartbeat = 60;      /* (secs) Default is 1 minute */
  36 static unsigned long wdt_status;
  37 static unsigned long boot_status;
  38
  39 #define WDT_TICK_RATE (IXP4XX_PERIPHERAL_BUS_CLOCK * 1000000UL)
  40
  41 #define WDT_IN_USE              0
  42 #define WDT_OK_TO_CLOSE         1
  43
  44 static void
  45 wdt_enable(void)
  46 {
  47         *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  48         *IXP4XX_OSWE = 0;
  49         *IXP4XX_OSWT = WDT_TICK_RATE * heartbeat;
  50         *IXP4XX_OSWE = IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE;
  51         *IXP4XX_OSWK = 0;
  52 }
  53
  54 static void
  55 wdt_disable(void)
  56 {
  57         *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  58         *IXP4XX_OSWE = 0;
  59         *IXP4XX_OSWK = 0;
  60 }
  61
  62 static int
  63 ixp4xx_wdt_open(struct inode *inode, struct file *file)
  64 {
  65         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  66                 return -EBUSY;
  67
  68         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  69
  70         wdt_enable();
  71
  72         return 0;
  73 }
  74
  75 static ssize_t
  76 ixp4xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  77 {
  78         /* Can't seek (pwrite) on this device  */
  79         if (ppos != &file->f_pos)
  80                 return -ESPIPE;
  81
  82         if (len) {
  83                 if (!nowayout) {
  84                         size_t i;
  85
  86                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  87
  88                         for (i = 0; i != len; i++) {
  89                                 char c;
  90
  91                                 if (get_user(c, data + i))
  92                                         return -EFAULT;
  93                                 if (c == 'V')
  94                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  95                         }
  96                 }
  97                 wdt_enable();
  98         }
  99
 100         return len;
 101 }
 102
 103 static struct watchdog_info ident = {
 104         .options        = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
 105                           WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 106         .identity       = "IXP4xx Watchdog",
 107 };
 108
 109
 110 static int
 111 ixp4xx_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 112                         unsigned long arg)
 113 {
 114         int ret = -ENOIOCTLCMD;
 115         int time;
 116
 117         switch (cmd) {
 118         case WDIOC_GETSUPPORT:
 119                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 120                                    sizeof(ident)) ? -EFAULT : 0;
 121                 break;
 122
 123         case WDIOC_GETSTATUS:
 124                 ret = put_user(0, (int *)arg);
 125                 break;
 126
 127         case WDIOC_GETBOOTSTATUS:
 128                 ret = put_user(boot_status, (int *)arg);
 129                 break;
 130
 131         case WDIOC_SETTIMEOUT:
 132                 ret = get_user(time, (int *)arg);
 133                 if (ret)
 134                         break;
 135
 136                 if (time <= 0 || time > 60) {
 137                         ret = -EINVAL;
 138                         break;
 139                 }
 140
 141                 heartbeat = time;
 142                 wdt_enable();
 143                 /* Fall through */
 144
 145         case WDIOC_GETTIMEOUT:
 146                 ret = put_user(heartbeat, (int *)arg);
 147                 break;
 148
 149         case WDIOC_KEEPALIVE:
 150                 wdt_enable();
 151                 ret = 0;
 152                 break;
 153         }
 154         return ret;
 155 }
 156
 157 static int
 158 ixp4xx_wdt_release(struct inode *inode, struct file *file)
 159 {
 160         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
 161                 wdt_disable();
 162         } else {
 163                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectdly - "
 164                                         "timer will not stop\n");
 165         }
 166
 167         clear_bit(WDT_IN_USE, &wdt_status);
 168         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 169
 170         return 0;
 171 }
 172
 173
 174 static struct file_operations ixp4xx_wdt_fops =
 175 {
 176         .owner          = THIS_MODULE,
 177         .write          = ixp4xx_wdt_write,
 178         .ioctl          = ixp4xx_wdt_ioctl,
 179         .open           = ixp4xx_wdt_open,
 180         .release        = ixp4xx_wdt_release,
 181 };
 182
 183 static struct miscdevice ixp4xx_wdt_miscdev =
 184 {
 185         .minor          = WATCHDOG_MINOR,
 186         .name           = "IXP4xx Watchdog",
 187         .fops           = &ixp4xx_wdt_fops,
 188 };
 189
 190 static int __init ixp4xx_wdt_init(void)
 191 {
 192         int ret;
 193         unsigned long processor_id;
 194
 195         asm("mrc p15, 0, %0, cr0, cr0, 0;" : "=r"(processor_id) :);
 196         if (!(processor_id & 0xf)) {
 197                 printk("IXP4XXX Watchdog: Rev. A0 CPU detected - "
 198                         "watchdog disabled\n");
 199
 200                 return -ENODEV;
 201         }
 202
 203         ret = misc_register(&ixp4xx_wdt_miscdev);
 204         if (ret == 0)
 205                 printk("IXP4xx Watchdog Timer: heartbeat %d sec\n", heartbeat);
 206
 207         boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ?
 208                         WDIOF_CARDRESET : 0;
 209
 210         return ret;
 211 }
 212
 213 static void __exit ixp4xx_wdt_exit(void)
 214 {
 215         misc_deregister(&ixp4xx_wdt_miscdev);
 216 }
 217
 218
 219 module_init(ixp4xx_wdt_init);
 220 module_exit(ixp4xx_wdt_exit);
 221
 222 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net">);
 223 MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
 224
 225 module_param(heartbeat, int, 0);
 226 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 227
 228 module_param(nowayout, int, 0);
 229 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 230
 231 MODULE_LICENSE("GPL");
 232 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 233