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 <linux/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_SETOPTIONS:
 181         {
 182                 int options;
 183                 int retval = -EINVAL;
 184
 185                 if (get_user(options, (int __user *)arg))
 186                         return -EFAULT;
 187
 188                 if (options & WDIOS_DISABLECARD) {
 189                         wdt_disable();
 190                         retval = 0;
 191                 }
 192
 193                 if (options & WDIOS_ENABLECARD) {
 194                         wdt_enable();
 195                         retval = 0;
 196                 }
 197
 198                 return retval;
 199         }
 200         case WDIOC_KEEPALIVE:
 201                 wdt_keepalive();
 202                 return 0;
 203         case WDIOC_SETTIMEOUT:
 204         {
 205                 int new_timeout;
 206
 207                 if (get_user(new_timeout, (int __user *)arg))
 208                         return -EFAULT;
 209
 210                 if (wdt_set_timeout(new_timeout))
 211                         return -EINVAL;
 212
 213                 /* Fall through */
 214         }
 215         case WDIOC_GETTIMEOUT:
 216                 return put_user(timeout, (int __user *)arg);
 217         default:
 218                 return -ENOTTY;
 219         }
 220 }
 221
 222 static const struct file_operations wdt_fops = {
 223         .owner = THIS_MODULE,
 224         .llseek = no_llseek,
 225         .write = fop_write,
 226         .open = fop_open,
 227         .release = fop_close,
 228         .unlocked_ioctl = fop_ioctl,
 229 };
 230
 231 static struct miscdevice wdt_miscdev = {
 232         .minor = WATCHDOG_MINOR,
 233         .name = "watchdog",
 234         .fops = &wdt_fops,
 235 };
 236
 237 /*
 238  *      Notifier for system down
 239  */
 240
 241 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 242                           void *unused)
 243 {
 244         if (code == SYS_DOWN || code == SYS_HALT)
 245                 wdt_disable();
 246         return NOTIFY_DONE;
 247 }
 248
 249 static struct notifier_block wdt_notifier = {
 250         .notifier_call = wdt_notify_sys,
 251 };
 252
 253 static void __exit sbc7240_wdt_unload(void)
 254 {
 255         printk(KERN_INFO SBC7240_PREFIX "Removing watchdog\n");
 256         misc_deregister(&wdt_miscdev);
 257
 258         unregister_reboot_notifier(&wdt_notifier);
 259         release_region(SBC7240_ENABLE_PORT, 1);
 260 }
 261
 262 static int __init sbc7240_wdt_init(void)
 263 {
 264         int rc = -EBUSY;
 265
 266         if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
 267                 printk(KERN_ERR SBC7240_PREFIX
 268                        "I/O address 0x%04x already in use\n",
 269                        SBC7240_ENABLE_PORT);
 270                 rc = -EIO;
 271                 goto err_out;
 272         }
 273
 274         /* The IO port 0x043 used to disable the watchdog
 275          * is already claimed by the system timer, so we
 276          * can't request_region() it ...*/
 277
 278         if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
 279                 timeout = SBC7240_TIMEOUT;
 280                 printk(KERN_INFO SBC7240_PREFIX
 281                        "timeout value must be 1<=x<=%d, using %d\n",
 282                        SBC7240_MAX_TIMEOUT, timeout);
 283         }
 284         wdt_set_timeout(timeout);
 285         wdt_disable();
 286
 287         rc = register_reboot_notifier(&wdt_notifier);
 288         if (rc) {
 289                 printk(KERN_ERR SBC7240_PREFIX
 290                        "cannot register reboot notifier (err=%d)\n", rc);
 291                 goto err_out_region;
 292         }
 293
 294         rc = misc_register(&wdt_miscdev);
 295         if (rc) {
 296                 printk(KERN_ERR SBC7240_PREFIX
 297                        "cannot register miscdev on minor=%d (err=%d)\n",
 298                        wdt_miscdev.minor, rc);
 299                 goto err_out_reboot_notifier;
 300         }
 301
 302         printk(KERN_INFO SBC7240_PREFIX
 303                "Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
 304                nowayout);
 305
 306         return 0;
 307
 308 err_out_reboot_notifier:
 309         unregister_reboot_notifier(&wdt_notifier);
 310 err_out_region:
 311         release_region(SBC7240_ENABLE_PORT, 1);
 312 err_out:
 313         return rc;
 314 }
 315
 316 module_init(sbc7240_wdt_init);
 317 module_exit(sbc7240_wdt_unload);
 318
 319 MODULE_AUTHOR("Gilles Gigan");
 320 MODULE_DESCRIPTION("Watchdog device driver for single board"
 321                    " computers EPIC Nano 7240 from iEi");
 322 MODULE_LICENSE("GPL");
 323 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 324