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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  28
  29 #include <linux/module.h>
  30 #include <linux/kernel.h>
  31 #include <linux/fs.h>
  32 #include <linux/init.h>
  33 #include <linux/device.h>
  34 #include <linux/miscdevice.h>
  35 #include <linux/watchdog.h>
  36 #include <linux/uaccess.h>
  37 #include <mach/hardware.h>
  38
  39 static bool nowayout = WATCHDOG_NOWAYOUT;
  40 static unsigned long wdt_status;
  41 static unsigned long boot_status;
  42 static DEFINE_SPINLOCK(wdt_lock);
  43
  44 #define WDT_IN_USE              0
  45 #define WDT_OK_TO_CLOSE         1
  46 #define WDT_ENABLED             2
  47
  48 static unsigned long iop_watchdog_timeout(void)
  49 {
  50         return (0xffffffffUL / get_iop_tick_rate());
  51 }
  52
  53 /**
  54  * wdt_supports_disable - determine if we are accessing a iop13xx watchdog
  55  * or iop3xx by whether it has a disable command
  56  */
  57 static int wdt_supports_disable(void)
  58 {
  59         int can_disable;
  60
  61         if (IOP_WDTCR_EN_ARM != IOP_WDTCR_DIS_ARM)
  62                 can_disable = 1;
  63         else
  64                 can_disable = 0;
  65
  66         return can_disable;
  67 }
  68
  69 static void wdt_enable(void)
  70 {
  71         /* Arm and enable the Timer to starting counting down from 0xFFFF.FFFF
  72          * Takes approx. 10.7s to timeout
  73          */
  74         spin_lock(&wdt_lock);
  75         write_wdtcr(IOP_WDTCR_EN_ARM);
  76         write_wdtcr(IOP_WDTCR_EN);
  77         spin_unlock(&wdt_lock);
  78 }
  79
  80 /* returns 0 if the timer was successfully disabled */
  81 static int wdt_disable(void)
  82 {
  83         /* Stop Counting */
  84         if (wdt_supports_disable()) {
  85                 spin_lock(&wdt_lock);
  86                 write_wdtcr(IOP_WDTCR_DIS_ARM);
  87                 write_wdtcr(IOP_WDTCR_DIS);
  88                 clear_bit(WDT_ENABLED, &wdt_status);
  89                 spin_unlock(&wdt_lock);
  90                 pr_info("Disabled\n");
  91                 return 0;
  92         } else
  93                 return 1;
  94 }
  95
  96 static int iop_wdt_open(struct inode *inode, struct file *file)
  97 {
  98         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  99                 return -EBUSY;
 100
 101         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 102         wdt_enable();
 103         set_bit(WDT_ENABLED, &wdt_status);
 104         return nonseekable_open(inode, file);
 105 }
 106
 107 static ssize_t iop_wdt_write(struct file *file, const char *data, size_t len,
 108                   loff_t *ppos)
 109 {
 110         if (len) {
 111                 if (!nowayout) {
 112                         size_t i;
 113
 114                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 115
 116                         for (i = 0; i != len; i++) {
 117                                 char c;
 118
 119                                 if (get_user(c, data + i))
 120                                         return -EFAULT;
 121                                 if (c == 'V')
 122                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 123                         }
 124                 }
 125                 wdt_enable();
 126         }
 127         return len;
 128 }
 129
 130 static const struct watchdog_info ident = {
 131         .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 132         .identity = "iop watchdog",
 133 };
 134
 135 static long iop_wdt_ioctl(struct file *file,
 136                                 unsigned int cmd, unsigned long arg)
 137 {
 138         int options;
 139         int ret = -ENOTTY;
 140         int __user *argp = (int __user *)arg;
 141
 142         switch (cmd) {
 143         case WDIOC_GETSUPPORT:
 144                 if (copy_to_user(argp, &ident, sizeof(ident)))
 145                         ret = -EFAULT;
 146                 else
 147                         ret = 0;
 148                 break;
 149
 150         case WDIOC_GETSTATUS:
 151                 ret = put_user(0, argp);
 152                 break;
 153
 154         case WDIOC_GETBOOTSTATUS:
 155                 ret = put_user(boot_status, argp);
 156                 break;
 157
 158         case WDIOC_SETOPTIONS:
 159                 if (get_user(options, (int *)arg))
 160                         return -EFAULT;
 161
 162                 if (options & WDIOS_DISABLECARD) {
 163                         if (!nowayout) {
 164                                 if (wdt_disable() == 0) {
 165                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 166                                         ret = 0;
 167                                 } else
 168                                         ret = -ENXIO;
 169                         } else
 170                                 ret = 0;
 171                 }
 172                 if (options & WDIOS_ENABLECARD) {
 173                         wdt_enable();
 174                         ret = 0;
 175                 }
 176                 break;
 177
 178         case WDIOC_KEEPALIVE:
 179                 wdt_enable();
 180                 ret = 0;
 181                 break;
 182
 183         case WDIOC_GETTIMEOUT:
 184                 ret = put_user(iop_watchdog_timeout(), argp);
 185                 break;
 186         }
 187         return ret;
 188 }
 189
 190 static int iop_wdt_release(struct inode *inode, struct file *file)
 191 {
 192         int state = 1;
 193         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 194                 if (test_bit(WDT_ENABLED, &wdt_status))
 195                         state = wdt_disable();
 196
 197         /* if the timer is not disabled reload and notify that we are still
 198          * going down
 199          */
 200         if (state != 0) {
 201                 wdt_enable();
 202                 pr_crit("Device closed unexpectedly - reset in %lu seconds\n",
 203                         iop_watchdog_timeout());
 204         }
 205
 206         clear_bit(WDT_IN_USE, &wdt_status);
 207         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 208
 209         return 0;
 210 }
 211
 212 static const struct file_operations iop_wdt_fops = {
 213         .owner = THIS_MODULE,
 214         .llseek = no_llseek,
 215         .write = iop_wdt_write,
 216         .unlocked_ioctl = iop_wdt_ioctl,
 217         .open = iop_wdt_open,
 218         .release = iop_wdt_release,
 219 };
 220
 221 static struct miscdevice iop_wdt_miscdev = {
 222         .minor = WATCHDOG_MINOR,
 223         .name = "watchdog",
 224         .fops = &iop_wdt_fops,
 225 };
 226
 227 static int __init iop_wdt_init(void)
 228 {
 229         int ret;
 230
 231         /* check if the reset was caused by the watchdog timer */
 232         boot_status = (read_rcsr() & IOP_RCSR_WDT) ? WDIOF_CARDRESET : 0;
 233
 234         /* Configure Watchdog Timeout to cause an Internal Bus (IB) Reset
 235          * NOTE: An IB Reset will Reset both cores in the IOP342
 236          */
 237         write_wdtsr(IOP13XX_WDTCR_IB_RESET);
 238
 239         /* Register after we have the device set up so we cannot race
 240            with an open */
 241         ret = misc_register(&iop_wdt_miscdev);
 242         if (ret == 0)
 243                 pr_info("timeout %lu sec\n", iop_watchdog_timeout());
 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, bool, 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");