drivers/watchdog/iop_wdt.c

   1 /*
   2  * drivers/char/watchdog/iop_wdt.c
   3  *
   4  * WDT driver for Intel I/O Processors
   5  * Copyright (C) 2005, Intel Corporation.
   6  *
   7  * Based on ixp4xx driver, Copyright 2004 (c) MontaVista, Software, Inc.
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms and conditions of the GNU General Public License,
  11  * version 2, as published by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope it will be useful, but WITHOUT
  14  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  16  * more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along with
  19  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  20  * Place - Suite 330, Boston, MA 02111-1307 USA.
  21  *
  22  *      Curt E Bruns <curt.e.bruns@intel.com>
  23  *      Peter Milne <peter.milne@d-tacq.com>
  24  *      Dan Williams <dan.j.williams@intel.com>
  25  */
  26
  27 #include <linux/module.h>
  28 #include <linux/kernel.h>
  29 #include <linux/fs.h>
  30 #include <linux/init.h>
  31 #include <linux/device.h>
  32 #include <linux/miscdevice.h>
  33 #include <linux/watchdog.h>
  34 #include <linux/uaccess.h>
  35 #include <mach/hardware.h>
  36
  37 static int nowayout = WATCHDOG_NOWAYOUT;
  38 static unsigned long wdt_status;
  39 static unsigned long boot_status;
  40 static spinlock_t wdt_lock;
  41
  42 #define WDT_IN_USE              0
  43 #define WDT_OK_TO_CLOSE         1
  44 #define WDT_ENABLED             2
  45
  46 static unsigned long iop_watchdog_timeout(void)
  47 {
  48         return (0xffffffffUL / get_iop_tick_rate());
  49 }
  50
  51 /**
  52  * wdt_supports_disable - determine if we are accessing a iop13xx watchdog
  53  * or iop3xx by whether it has a disable command
  54  */
  55 static int wdt_supports_disable(void)
  56 {
  57         int can_disable;
  58
  59         if (IOP_WDTCR_EN_ARM != IOP_WDTCR_DIS_ARM)
  60                 can_disable = 1;
  61         else
  62                 can_disable = 0;
  63
  64         return can_disable;
  65 }
  66
  67 static void wdt_enable(void)
  68 {
  69         /* Arm and enable the Timer to starting counting down from 0xFFFF.FFFF
  70          * Takes approx. 10.7s to timeout
  71          */
  72         spin_lock(&wdt_lock);
  73         write_wdtcr(IOP_WDTCR_EN_ARM);
  74         write_wdtcr(IOP_WDTCR_EN);
  75         spin_unlock(&wdt_lock);
  76 }
  77
  78 /* returns 0 if the timer was successfully disabled */
  79 static int wdt_disable(void)
  80 {
  81         /* Stop Counting */
  82         if (wdt_supports_disable()) {
  83                 spin_lock(&wdt_lock);
  84                 write_wdtcr(IOP_WDTCR_DIS_ARM);
  85                 write_wdtcr(IOP_WDTCR_DIS);
  86                 clear_bit(WDT_ENABLED, &wdt_status);
  87                 spin_unlock(&wdt_lock);
  88                 printk(KERN_INFO "WATCHDOG: Disabled\n");
  89                 return 0;
  90         } else
  91                 return 1;
  92 }
  93
  94 static int iop_wdt_open(struct inode *inode, struct file *file)
  95 {
  96         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  97                 return -EBUSY;
  98
  99         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 100         wdt_enable();
 101         set_bit(WDT_ENABLED, &wdt_status);
 102         return nonseekable_open(inode, file);
 103 }
 104
 105 static ssize_t iop_wdt_write(struct file *file, const char *data, size_t len,
 106                   loff_t *ppos)
 107 {
 108         if (len) {
 109                 if (!nowayout) {
 110                         size_t i;
 111
 112                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 113
 114                         for (i = 0; i != len; i++) {
 115                                 char c;
 116
 117                                 if (get_user(c, data + i))
 118                                         return -EFAULT;
 119                                 if (c == 'V')
 120                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 121                         }
 122                 }
 123                 wdt_enable();
 124         }
 125         return len;
 126 }
 127
 128 static const struct watchdog_info ident = {
 129         .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 130         .identity = "iop watchdog",
 131 };
 132
 133 static long iop_wdt_ioctl(struct file *file,
 134                                 unsigned int cmd, unsigned long arg)
 135 {
 136         int options;
 137         int ret = -ENOTTY;
 138         int __user *argp = (int __user *)arg;
 139
 140         switch (cmd) {
 141         case WDIOC_GETSUPPORT:
 142                 if (copy_to_user(argp, &ident, sizeof(ident)))
 143                         ret = -EFAULT;
 144                 else
 145                         ret = 0;
 146                 break;
 147
 148         case WDIOC_GETSTATUS:
 149                 ret = put_user(0, argp);
 150                 break;
 151
 152         case WDIOC_GETBOOTSTATUS:
 153                 ret = put_user(boot_status, argp);
 154                 break;
 155
 156         case WDIOC_SETOPTIONS:
 157                 if (get_user(options, (int *)arg))
 158                         return -EFAULT;
 159
 160                 if (options & WDIOS_DISABLECARD) {
 161                         if (!nowayout) {
 162                                 if (wdt_disable() == 0) {
 163                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 164                                         ret = 0;
 165                                 } else
 166                                         ret = -ENXIO;
 167                         } else
 168                                 ret = 0;
 169                 }
 170                 if (options & WDIOS_ENABLECARD) {
 171                         wdt_enable();
 172                         ret = 0;
 173                 }
 174                 break;
 175
 176         case WDIOC_KEEPALIVE:
 177                 wdt_enable();
 178                 ret = 0;
 179                 break;
 180
 181         case WDIOC_GETTIMEOUT:
 182                 ret = put_user(iop_watchdog_timeout(), argp);
 183                 break;
 184         }
 185         return ret;
 186 }
 187
 188 static int iop_wdt_release(struct inode *inode, struct file *file)
 189 {
 190         int state = 1;
 191         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 192                 if (test_bit(WDT_ENABLED, &wdt_status))
 193                         state = wdt_disable();
 194
 195         /* if the timer is not disabled reload and notify that we are still
 196          * going down
 197          */
 198         if (state != 0) {
 199                 wdt_enable();
 200                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
 201                        "reset in %lu seconds\n", iop_watchdog_timeout());
 202         }
 203
 204         clear_bit(WDT_IN_USE, &wdt_status);
 205         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 206
 207         return 0;
 208 }
 209
 210 static const struct file_operations iop_wdt_fops = {
 211         .owner = THIS_MODULE,
 212         .llseek = no_llseek,
 213         .write = iop_wdt_write,
 214         .unlocked_ioctl = iop_wdt_ioctl,
 215         .open = iop_wdt_open,
 216         .release = iop_wdt_release,
 217 };
 218
 219 static struct miscdevice iop_wdt_miscdev = {
 220         .minor = WATCHDOG_MINOR,
 221         .name = "watchdog",
 222         .fops = &iop_wdt_fops,
 223 };
 224
 225 static int __init iop_wdt_init(void)
 226 {
 227         int ret;
 228
 229         spin_lock_init(&wdt_lock);
 230
 231
 232         /* check if the reset was caused by the watchdog timer */
 233         boot_status = (read_rcsr() & IOP_RCSR_WDT) ? WDIOF_CARDRESET : 0;
 234
 235         /* Configure Watchdog Timeout to cause an Internal Bus (IB) Reset
 236          * NOTE: An IB Reset will Reset both cores in the IOP342
 237          */
 238         write_wdtsr(IOP13XX_WDTCR_IB_RESET);
 239
 240         /* Register after we have the device set up so we cannot race
 241            with an open */
 242         ret = misc_register(&iop_wdt_miscdev);
 243         if (ret == 0)
 244                 printk(KERN_INFO "iop watchdog timer: timeout %lu sec\n",
 245                        iop_watchdog_timeout());
 246
 247         return ret;
 248 }
 249
 250 static void __exit iop_wdt_exit(void)
 251 {
 252         misc_deregister(&iop_wdt_miscdev);
 253 }
 254
 255 module_init(iop_wdt_init);
 256 module_exit(iop_wdt_exit);
 257
 258 module_param(nowayout, int, 0);
 259 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 260
 261 MODULE_AUTHOR("Curt E Bruns <curt.e.bruns@intel.com>");
 262 MODULE_DESCRIPTION("iop watchdog timer driver");
 263 MODULE_LICENSE("GPL");
 264 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);