drivers/watchdog/sbc7240_wdt.c

   1 /*
   2  *      NANO7240 SBC Watchdog device driver
   3  *
   4  *      Based on w83877f.c by Scott Jennings,
   5  *
   6  *      This program is free software; you can redistribute it and/or modify
   7  *      it under the terms of the GNU General Public License version 2 as
   8  *      published by the Free Software Foundation;
   9  *
  10  *      Software distributed under the License is distributed on an "AS IS"
  11  *      basis, WITHOUT WARRANTY OF ANY KIND, either express or
  12  *      implied. See the License for the specific language governing
  13  *      rights and limitations under the License.
  14  *
  15  *      (c) Copyright 2007  Gilles GIGAN <gilles.gigan@jcu.edu.au>
  16  *
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/init.h>
  21 #include <linux/ioport.h>
  22 #include <linux/jiffies.h>
  23 #include <linux/module.h>
  24 #include <linux/moduleparam.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/notifier.h>
  27 #include <linux/reboot.h>
  28 #include <linux/types.h>
  29 #include <linux/watchdog.h>
  30 #include <linux/io.h>
  31 #include <linux/uaccess.h>
  32 #include <asm/atomic.h>
  33 #include <asm/system.h>
  34
  35 #define SBC7240_PREFIX "sbc7240_wdt: "
  36
  37 #define SBC7240_ENABLE_PORT             0x443
  38 #define SBC7240_DISABLE_PORT            0x043
  39 #define SBC7240_SET_TIMEOUT_PORT        SBC7240_ENABLE_PORT
  40 #define SBC7240_MAGIC_CHAR              'V'
  41
  42 #define SBC7240_TIMEOUT         30
  43 #define SBC7240_MAX_TIMEOUT             255
  44 static int timeout = SBC7240_TIMEOUT;   /* in seconds */
  45 module_param(timeout, int, 0);
  46 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<="
  47                  __MODULE_STRING(SBC7240_MAX_TIMEOUT) ", default="
  48                  __MODULE_STRING(SBC7240_TIMEOUT) ")");
  49
  50 static int nowayout = WATCHDOG_NOWAYOUT;
  51 module_param(nowayout, int, 0);
  52 MODULE_PARM_DESC(nowayout, "Disable watchdog when closing device file");
  53
  54 #define SBC7240_OPEN_STATUS_BIT         0
  55 #define SBC7240_ENABLED_STATUS_BIT      1
  56 #define SBC7240_EXPECT_CLOSE_STATUS_BIT 2
  57 static unsigned long wdt_status;
  58
  59 /*
  60  * Utility routines
  61  */
  62
  63 static void wdt_disable(void)
  64 {
  65         /* disable the watchdog */
  66         if (test_and_clear_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
  67                 inb_p(SBC7240_DISABLE_PORT);
  68                 printk(KERN_INFO SBC7240_PREFIX
  69                        "Watchdog timer is now disabled.\n");
  70         }
  71 }
  72
  73 static void wdt_enable(void)
  74 {
  75         /* enable the watchdog */
  76         if (!test_and_set_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
  77                 inb_p(SBC7240_ENABLE_PORT);
  78                 printk(KERN_INFO SBC7240_PREFIX
  79                        "Watchdog timer is now enabled.\n");
  80         }
  81 }
  82
  83 static int wdt_set_timeout(int t)
  84 {
  85         if (t < 1 || t > SBC7240_MAX_TIMEOUT) {
  86                 printk(KERN_ERR SBC7240_PREFIX
  87                        "timeout value must be 1<=x<=%d\n",
  88                        SBC7240_MAX_TIMEOUT);
  89                 return -1;
  90         }
  91         /* set the timeout */
  92         outb_p((unsigned)t, SBC7240_SET_TIMEOUT_PORT);
  93         timeout = t;
  94         printk(KERN_INFO SBC7240_PREFIX "timeout set to %d seconds\n", t);
  95         return 0;
  96 }
  97
  98 /* Whack the dog */
  99 static inline void wdt_keepalive(void)
 100 {
 101         if (test_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status))
 102                 inb_p(SBC7240_ENABLE_PORT);
 103 }
 104
 105 /*
 106  * /dev/watchdog handling
 107  */
 108 static ssize_t fop_write(struct file *file, const char __user *buf,
 109                          size_t count, loff_t *ppos)
 110 {
 111         size_t i;
 112         char c;
 113
 114         if (count) {
 115                 if (!nowayout) {
 116                         clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
 117                                 &wdt_status);
 118
 119                         /* is there a magic char ? */
 120                         for (i = 0; i != count; i++) {
 121                                 if (get_user(c, buf + i))
 122                                         return -EFAULT;
 123                                 if (c == SBC7240_MAGIC_CHAR) {
 124                                         set_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
 125                                                 &wdt_status);
 126                                         break;
 127                                 }
 128                         }
 129                 }
 130
 131                 wdt_keepalive();
 132         }
 133
 134         return count;
 135 }
 136
 137 static int fop_open(struct inode *inode, struct file *file)
 138 {
 139         if (test_and_set_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status))
 140                 return -EBUSY;
 141
 142         wdt_enable();
 143
 144         return nonseekable_open(inode, file);
 145 }
 146
 147 static int fop_close(struct inode *inode, struct file *file)
 148 {
 149         if (test_and_clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT, &wdt_status)
 150             || !nowayout) {
 151                 wdt_disable();
 152         } else {
 153                 printk(KERN_CRIT SBC7240_PREFIX
 154                        "Unexpected close, not stopping watchdog!\n");
 155                 wdt_keepalive();
 156         }
 157
 158         clear_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status);
 159         return 0;
 160 }
 161
 162 static const struct watchdog_info ident = {
 163         .options = WDIOF_KEEPALIVEPING|
 164                    WDIOF_SETTIMEOUT|
 165                    WDIOF_MAGICCLOSE,
 166         .firmware_version = 1,
 167         .identity = "SBC7240",
 168 };
 169
 170
 171 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 172 {
 173         switch (cmd) {
 174         case WDIOC_GETSUPPORT:
 175                 return copy_to_user((void __user *)arg, &ident, sizeof(ident))
 176                                                  ? -EFAULT : 0;
 177         case WDIOC_GETSTATUS:
 178         case WDIOC_GETBOOTSTATUS:
 179                 return put_user(0, (int __user *)arg);
 180         case WDIOC_KEEPALIVE:
 181                 wdt_keepalive();
 182                 return 0;
 183         case WDIOC_SETOPTIONS:{
 184                         int options;
 185                         int retval = -EINVAL;
 186
 187                         if (get_user(options, (int __user *)arg))
 188                                 return -EFAULT;
 189
 190                         if (options & WDIOS_DISABLECARD) {
 191                                 wdt_disable();
 192                                 retval = 0;
 193                         }
 194
 195                         if (options & WDIOS_ENABLECARD) {
 196                                 wdt_enable();
 197                                 retval = 0;
 198                         }
 199
 200                         return retval;
 201                 }
 202         case WDIOC_SETTIMEOUT:{
 203                         int new_timeout;
 204
 205                         if (get_user(new_timeout, (int __user *)arg))
 206                                 return -EFAULT;
 207
 208                         if (wdt_set_timeout(new_timeout))
 209                                 return -EINVAL;
 210
 211                         /* Fall through */
 212                 }
 213         case WDIOC_GETTIMEOUT:
 214                 return put_user(timeout, (int __user *)arg);
 215         default:
 216                 return -ENOTTY;
 217         }
 218 }
 219
 220 static const struct file_operations wdt_fops = {
 221         .owner = THIS_MODULE,
 222         .llseek = no_llseek,
 223         .write = fop_write,
 224         .open = fop_open,
 225         .release = fop_close,
 226         .unlocked_ioctl = fop_ioctl,
 227 };
 228
 229 static struct miscdevice wdt_miscdev = {
 230         .minor = WATCHDOG_MINOR,
 231         .name = "watchdog",
 232         .fops = &wdt_fops,
 233 };
 234
 235 /*
 236  *      Notifier for system down
 237  */
 238
 239 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 240                           void *unused)
 241 {
 242         if (code == SYS_DOWN || code == SYS_HALT)
 243                 wdt_disable();
 244         return NOTIFY_DONE;
 245 }
 246
 247 static struct notifier_block wdt_notifier = {
 248         .notifier_call = wdt_notify_sys,
 249 };
 250
 251 static void __exit sbc7240_wdt_unload(void)
 252 {
 253         printk(KERN_INFO SBC7240_PREFIX "Removing watchdog\n");
 254         misc_deregister(&wdt_miscdev);
 255
 256         unregister_reboot_notifier(&wdt_notifier);
 257         release_region(SBC7240_ENABLE_PORT, 1);
 258 }
 259
 260 static int __init sbc7240_wdt_init(void)
 261 {
 262         int rc = -EBUSY;
 263
 264         if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
 265                 printk(KERN_ERR SBC7240_PREFIX
 266                        "I/O address 0x%04x already in use\n",
 267                        SBC7240_ENABLE_PORT);
 268                 rc = -EIO;
 269                 goto err_out;
 270         }
 271
 272         /* The IO port 0x043 used to disable the watchdog
 273          * is already claimed by the system timer, so we
 274          * cant request_region() it ...*/
 275
 276         if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
 277                 timeout = SBC7240_TIMEOUT;
 278                 printk(KERN_INFO SBC7240_PREFIX
 279                        "timeout value must be 1<=x<=%d, using %d\n",
 280                        SBC7240_MAX_TIMEOUT, timeout);
 281         }
 282         wdt_set_timeout(timeout);
 283         wdt_disable();
 284
 285         rc = register_reboot_notifier(&wdt_notifier);
 286         if (rc) {
 287                 printk(KERN_ERR SBC7240_PREFIX
 288                        "cannot register reboot notifier (err=%d)\n", rc);
 289                 goto err_out_region;
 290         }
 291
 292         rc = misc_register(&wdt_miscdev);
 293         if (rc) {
 294                 printk(KERN_ERR SBC7240_PREFIX
 295                        "cannot register miscdev on minor=%d (err=%d)\n",
 296                        wdt_miscdev.minor, rc);
 297                 goto err_out_reboot_notifier;
 298         }
 299
 300         printk(KERN_INFO SBC7240_PREFIX
 301                "Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
 302                nowayout);
 303
 304         return 0;
 305
 306 err_out_reboot_notifier:
 307         unregister_reboot_notifier(&wdt_notifier);
 308 err_out_region:
 309         release_region(SBC7240_ENABLE_PORT, 1);
 310 err_out:
 311         return rc;
 312 }
 313
 314 module_init(sbc7240_wdt_init);
 315 module_exit(sbc7240_wdt_unload);
 316
 317 MODULE_AUTHOR("Gilles Gigan");
 318 MODULE_DESCRIPTION("Watchdog device driver for single board"
 319                    " computers EPIC Nano 7240 from iEi");
 320 MODULE_LICENSE("GPL");
 321 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 322