drivers/char/watchdog/ixp4xx_wdt.c

   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
  26 #include <asm/hardware.h>
  27 #include <asm/uaccess.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
  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
  40 wdt_enable(void)
  41 {
  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 }
  48
  49 static void
  50 wdt_disable(void)
  51 {
  52         *IXP4XX_OSWK = IXP4XX_WDT_KEY;
  53         *IXP4XX_OSWE = 0;
  54         *IXP4XX_OSWK = 0;
  55 }
  56
  57 static int
  58 ixp4xx_wdt_open(struct inode *inode, struct file *file)
  59 {
  60         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  61                 return -EBUSY;
  62
  63         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  64
  65         wdt_enable();
  66
  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
  91         return len;
  92 }
  93
  94 static struct watchdog_info ident = {
  95         .options        = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
  96                           WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  97         .identity       = "IXP4xx Watchdog",
  98 };
  99
 100
 101 static int
 102 ixp4xx_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 103                         unsigned long arg)
 104 {
 105         int ret = -ENOTTY;
 106         int time;
 107
 108         switch (cmd) {
 109         case WDIOC_GETSUPPORT:
 110                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 111                                    sizeof(ident)) ? -EFAULT : 0;
 112                 break;
 113
 114         case WDIOC_GETSTATUS:
 115                 ret = put_user(0, (int *)arg);
 116                 break;
 117
 118         case WDIOC_GETBOOTSTATUS:
 119                 ret = put_user(boot_status, (int *)arg);
 120                 break;
 121
 122         case WDIOC_SETTIMEOUT:
 123                 ret = get_user(time, (int *)arg);
 124                 if (ret)
 125                         break;
 126
 127                 if (time <= 0 || time > 60) {
 128                         ret = -EINVAL;
 129                         break;
 130                 }
 131
 132                 heartbeat = time;
 133                 wdt_enable();
 134                 /* Fall through */
 135
 136         case WDIOC_GETTIMEOUT:
 137                 ret = put_user(heartbeat, (int *)arg);
 138                 break;
 139
 140         case WDIOC_KEEPALIVE:
 141                 wdt_enable();
 142                 ret = 0;
 143                 break;
 144         }
 145         return ret;
 146 }
 147
 148 static int
 149 ixp4xx_wdt_release(struct inode *inode, struct file *file)
 150 {
 151         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
 152                 wdt_disable();
 153         } else {
 154                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
 155                                         "timer will not stop\n");
 156         }
 157
 158         clear_bit(WDT_IN_USE, &wdt_status);
 159         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 160
 161         return 0;
 162 }
 163
 164
 165 static const struct file_operations ixp4xx_wdt_fops =
 166 {
 167         .owner          = THIS_MODULE,
 168         .llseek         = no_llseek,
 169         .write          = ixp4xx_wdt_write,
 170         .ioctl          = ixp4xx_wdt_ioctl,
 171         .open           = ixp4xx_wdt_open,
 172         .release        = ixp4xx_wdt_release,
 173 };
 174
 175 static struct miscdevice ixp4xx_wdt_miscdev =
 176 {
 177         .minor          = WATCHDOG_MINOR,
 178         .name           = "watchdog",
 179         .fops           = &ixp4xx_wdt_fops,
 180 };
 181
 182 static int __init ixp4xx_wdt_init(void)
 183 {
 184         int ret;
 185         unsigned long processor_id;
 186
 187         asm("mrc p15, 0, %0, cr0, cr0, 0;" : "=r"(processor_id) :);
 188         if (!(processor_id & 0xf) && !cpu_is_ixp46x()) {
 189                 printk("IXP4XXX Watchdog: Rev. A0 IXP42x CPU detected - "
 190                         "watchdog disabled\n");
 191
 192                 return -ENODEV;
 193         }
 194
 195         ret = misc_register(&ixp4xx_wdt_miscdev);
 196         if (ret == 0)
 197                 printk("IXP4xx Watchdog Timer: heartbeat %d sec\n", heartbeat);
 198
 199         boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ?
 200                         WDIOF_CARDRESET : 0;
 201
 202         return ret;
 203 }
 204
 205 static void __exit ixp4xx_wdt_exit(void)
 206 {
 207         misc_deregister(&ixp4xx_wdt_miscdev);
 208 }
 209
 210
 211 module_init(ixp4xx_wdt_init);
 212 module_exit(ixp4xx_wdt_exit);
 213
 214 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 215 MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
 216
 217 module_param(heartbeat, int, 0);
 218 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 219
 220 module_param(nowayout, int, 0);
 221 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 222
 223 MODULE_LICENSE("GPL");
 224 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 225