drivers/watchdog/ixp2000_wdt.c

   1 /*
   2  * drivers/char/watchdog/ixp2000_wdt.c
   3  *
   4  * Watchdog driver for Intel IXP2000 network processors
   5  *
   6  * Adapted from the IXP4xx watchdog driver by Lennert Buytenhek.
   7  * The original version carries these notices:
   8  *
   9  * Author: Deepak Saxena <dsaxena@plexity.net>
  10  *
  11  * Copyright 2004 (c) MontaVista, Software, Inc.
  12  * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  13  *
  14  * This file is licensed under  the terms of the GNU General Public
  15  * License version 2. This program is licensed "as is" without any
  16  * warranty of any kind, whether express or implied.
  17  */
  18
  19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/types.h>
  24 #include <linux/timer.h>
  25 #include <linux/kernel.h>
  26 #include <linux/fs.h>
  27 #include <linux/miscdevice.h>
  28 #include <linux/watchdog.h>
  29 #include <linux/init.h>
  30 #include <linux/bitops.h>
  31 #include <linux/uaccess.h>
  32 #include <mach/hardware.h>
  33
  34 static bool nowayout = WATCHDOG_NOWAYOUT;
  35 static unsigned int heartbeat = 60;     /* (secs) Default is 1 minute */
  36 static unsigned long wdt_status;
  37 static DEFINE_SPINLOCK(wdt_lock);
  38
  39 #define WDT_IN_USE              0
  40 #define WDT_OK_TO_CLOSE         1
  41
  42 static unsigned long wdt_tick_rate;
  43
  44 static void wdt_enable(void)
  45 {
  46         spin_lock(&wdt_lock);
  47         ixp2000_reg_write(IXP2000_RESET0, *(IXP2000_RESET0) | WDT_RESET_ENABLE);
  48         ixp2000_reg_write(IXP2000_TWDE, WDT_ENABLE);
  49         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
  50         ixp2000_reg_write(IXP2000_T4_CTL, TIMER_DIVIDER_256 | TIMER_ENABLE);
  51         spin_unlock(&wdt_lock);
  52 }
  53
  54 static void wdt_disable(void)
  55 {
  56         spin_lock(&wdt_lock);
  57         ixp2000_reg_write(IXP2000_T4_CTL, 0);
  58         spin_unlock(&wdt_lock);
  59 }
  60
  61 static void wdt_keepalive(void)
  62 {
  63         spin_lock(&wdt_lock);
  64         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
  65         spin_unlock(&wdt_lock);
  66 }
  67
  68 static int ixp2000_wdt_open(struct inode *inode, struct file *file)
  69 {
  70         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  71                 return -EBUSY;
  72
  73         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  74
  75         wdt_enable();
  76
  77         return nonseekable_open(inode, file);
  78 }
  79
  80 static ssize_t ixp2000_wdt_write(struct file *file, const char *data,
  81                                                 size_t len, loff_t *ppos)
  82 {
  83         if (len) {
  84                 if (!nowayout) {
  85                         size_t i;
  86
  87                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  88
  89                         for (i = 0; i != len; i++) {
  90                                 char c;
  91
  92                                 if (get_user(c, data + i))
  93                                         return -EFAULT;
  94                                 if (c == 'V')
  95                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  96                         }
  97                 }
  98                 wdt_keepalive();
  99         }
 100
 101         return len;
 102 }
 103
 104
 105 static const struct watchdog_info ident = {
 106         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 107                                 WDIOF_KEEPALIVEPING,
 108         .identity       = "IXP2000 Watchdog",
 109 };
 110
 111 static long ixp2000_wdt_ioctl(struct file *file, unsigned int cmd,
 112                                                         unsigned long arg)
 113 {
 114         int ret = -ENOTTY;
 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(0, (int *)arg);
 129                 break;
 130
 131         case WDIOC_KEEPALIVE:
 132                 wdt_enable();
 133                 ret = 0;
 134                 break;
 135
 136         case WDIOC_SETTIMEOUT:
 137                 ret = get_user(time, (int *)arg);
 138                 if (ret)
 139                         break;
 140
 141                 if (time <= 0 || time > 60) {
 142                         ret = -EINVAL;
 143                         break;
 144                 }
 145
 146                 heartbeat = time;
 147                 wdt_keepalive();
 148                 /* Fall through */
 149
 150         case WDIOC_GETTIMEOUT:
 151                 ret = put_user(heartbeat, (int *)arg);
 152                 break;
 153         }
 154
 155         return ret;
 156 }
 157
 158 static int ixp2000_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                 pr_crit("Device closed unexpectedly - timer will not stop\n");
 164         clear_bit(WDT_IN_USE, &wdt_status);
 165         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 166
 167         return 0;
 168 }
 169
 170
 171 static const struct file_operations ixp2000_wdt_fops = {
 172         .owner          = THIS_MODULE,
 173         .llseek         = no_llseek,
 174         .write          = ixp2000_wdt_write,
 175         .unlocked_ioctl = ixp2000_wdt_ioctl,
 176         .open           = ixp2000_wdt_open,
 177         .release        = ixp2000_wdt_release,
 178 };
 179
 180 static struct miscdevice ixp2000_wdt_miscdev = {
 181         .minor          = WATCHDOG_MINOR,
 182         .name           = "watchdog",
 183         .fops           = &ixp2000_wdt_fops,
 184 };
 185
 186 static int __init ixp2000_wdt_init(void)
 187 {
 188         if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
 189                 pr_info("Unable to use IXP2000 watchdog due to IXP2800 erratum #25\n");
 190                 return -EIO;
 191         }
 192         wdt_tick_rate = (*IXP2000_T1_CLD * HZ) / 256;
 193         return misc_register(&ixp2000_wdt_miscdev);
 194 }
 195
 196 static void __exit ixp2000_wdt_exit(void)
 197 {
 198         misc_deregister(&ixp2000_wdt_miscdev);
 199 }
 200
 201 module_init(ixp2000_wdt_init);
 202 module_exit(ixp2000_wdt_exit);
 203
 204 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 205 MODULE_DESCRIPTION("IXP2000 Network Processor Watchdog");
 206
 207 module_param(heartbeat, int, 0);
 208 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
 209
 210 module_param(nowayout, bool, 0);
 211 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 212
 213 MODULE_LICENSE("GPL");
 214 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 215