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 <asm/hardware.h>
  36
  37 static int nowayout = WATCHDOG_NOWAYOUT;
  38 static unsigned long wdt_status;
  39 static unsigned long boot_status;
  40
  41 #define WDT_IN_USE              0
  42 #define WDT_OK_TO_CLOSE         1
  43 #define WDT_ENABLED             2
  44
  45 static unsigned long iop_watchdog_timeout(void)
  46 {
  47         return (0xffffffffUL / get_iop_tick_rate());
  48 }
  49
  50 /**
  51  * wdt_supports_disable - determine if we are accessing a iop13xx watchdog
  52  * or iop3xx by whether it has a disable command
  53  */
  54 static int wdt_supports_disable(void)
  55 {
  56         int can_disable;
  57
  58         if (IOP_WDTCR_EN_ARM != IOP_WDTCR_DIS_ARM)
  59                 can_disable = 1;
  60         else
  61                 can_disable = 0;
  62
  63         return can_disable;
  64 }
  65
  66 static void wdt_enable(void)
  67 {
  68         /* Arm and enable the Timer to starting counting down from 0xFFFF.FFFF
  69          * Takes approx. 10.7s to timeout
  70          */
  71         write_wdtcr(IOP_WDTCR_EN_ARM);
  72         write_wdtcr(IOP_WDTCR_EN);
  73 }
  74
  75 /* returns 0 if the timer was successfully disabled */
  76 static int wdt_disable(void)
  77 {
  78         /* Stop Counting */
  79         if (wdt_supports_disable()) {
  80                 write_wdtcr(IOP_WDTCR_DIS_ARM);
  81                 write_wdtcr(IOP_WDTCR_DIS);
  82                 clear_bit(WDT_ENABLED, &wdt_status);
  83                 printk(KERN_INFO "WATCHDOG: Disabled\n");
  84                 return 0;
  85         } else
  86                 return 1;
  87 }
  88
  89 static int iop_wdt_open(struct inode *inode, struct file *file)
  90 {
  91         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  92                 return -EBUSY;
  93
  94         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  95
  96         wdt_enable();
  97
  98         set_bit(WDT_ENABLED, &wdt_status);
  99
 100         return nonseekable_open(inode, file);
 101 }
 102
 103 static ssize_t
 104 iop_wdt_write(struct file *file, const char *data, size_t len,
 105                   loff_t *ppos)
 106 {
 107         if (len) {
 108                 if (!nowayout) {
 109                         size_t i;
 110
 111                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 112
 113                         for (i = 0; i != len; i++) {
 114                                 char c;
 115
 116                                 if (get_user(c, data + i))
 117                                         return -EFAULT;
 118                                 if (c == 'V')
 119                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 120                         }
 121                 }
 122                 wdt_enable();
 123         }
 124
 125         return len;
 126 }
 127
 128 static struct watchdog_info ident = {
 129         .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 130         .identity = "iop watchdog",
 131 };
 132
 133 static int
 134 iop_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 135                   unsigned long arg)
 136 {
 137         int options;
 138         int ret = -ENOTTY;
 139
 140         switch (cmd) {
 141         case WDIOC_GETSUPPORT:
 142                 if (copy_to_user
 143                     ((struct watchdog_info *)arg, &ident, sizeof ident))
 144                         ret = -EFAULT;
 145                 else
 146                         ret = 0;
 147                 break;
 148
 149         case WDIOC_GETSTATUS:
 150                 ret = put_user(0, (int *)arg);
 151                 break;
 152
 153         case WDIOC_GETBOOTSTATUS:
 154                 ret = put_user(boot_status, (int *)arg);
 155                 break;
 156
 157         case WDIOC_GETTIMEOUT:
 158                 ret = put_user(iop_watchdog_timeout(), (int *)arg);
 159                 break;
 160
 161         case WDIOC_KEEPALIVE:
 162                 wdt_enable();
 163                 ret = 0;
 164                 break;
 165
 166         case WDIOC_SETOPTIONS:
 167                 if (get_user(options, (int *)arg))
 168                         return -EFAULT;
 169
 170                 if (options & WDIOS_DISABLECARD) {
 171                         if (!nowayout) {
 172                                 if (wdt_disable() == 0) {
 173                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 174                                         ret = 0;
 175                                 } else
 176                                         ret = -ENXIO;
 177                         } else
 178                                 ret = 0;
 179                 }
 180
 181                 if (options & WDIOS_ENABLECARD) {
 182                         wdt_enable();
 183                         ret = 0;
 184                 }
 185                 break;
 186         }
 187
 188         return ret;
 189 }
 190
 191 static int iop_wdt_release(struct inode *inode, struct file *file)
 192 {
 193         int state = 1;
 194         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 195                 if (test_bit(WDT_ENABLED, &wdt_status))
 196                         state = wdt_disable();
 197
 198         /* if the timer is not disbaled reload and notify that we are still
 199          * going down
 200          */
 201         if (state != 0) {
 202                 wdt_enable();
 203                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
 204                        "reset in %lu seconds\n", iop_watchdog_timeout());
 205         }
 206
 207         clear_bit(WDT_IN_USE, &wdt_status);
 208         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 209
 210         return 0;
 211 }
 212
 213 static const struct file_operations iop_wdt_fops = {
 214         .owner = THIS_MODULE,
 215         .llseek = no_llseek,
 216         .write = iop_wdt_write,
 217         .ioctl = iop_wdt_ioctl,
 218         .open = iop_wdt_open,
 219         .release = iop_wdt_release,
 220 };
 221
 222 static struct miscdevice iop_wdt_miscdev = {
 223         .minor = WATCHDOG_MINOR,
 224         .name = "watchdog",
 225         .fops = &iop_wdt_fops,
 226 };
 227
 228 static int __init iop_wdt_init(void)
 229 {
 230         int ret;
 231
 232         ret = misc_register(&iop_wdt_miscdev);
 233         if (ret == 0)
 234                 printk("iop watchdog timer: timeout %lu sec\n",
 235                        iop_watchdog_timeout());
 236
 237         /* check if the reset was caused by the watchdog timer */
 238         boot_status = (read_rcsr() & IOP_RCSR_WDT) ? WDIOF_CARDRESET : 0;
 239
 240         /* Configure Watchdog Timeout to cause an Internal Bus (IB) Reset
 241          * NOTE: An IB Reset will Reset both cores in the IOP342
 242          */
 243         write_wdtsr(IOP13XX_WDTCR_IB_RESET);
 244
 245         return ret;
 246 }
 247
 248 static void __exit iop_wdt_exit(void)
 249 {
 250         misc_deregister(&iop_wdt_miscdev);
 251 }
 252
 253 module_init(iop_wdt_init);
 254 module_exit(iop_wdt_exit);
 255
 256 module_param(nowayout, int, 0);
 257 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 258
 259 MODULE_AUTHOR("Curt E Bruns <curt.e.bruns@intel.com>");
 260 MODULE_DESCRIPTION("iop watchdog timer driver");
 261 MODULE_LICENSE("GPL");
 262 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);