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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/fs.h>
  22 #include <linux/init.h>
  23 #include <linux/ioport.h>
  24 #include <linux/jiffies.h>
  25 #include <linux/module.h>
  26 #include <linux/moduleparam.h>
  27 #include <linux/miscdevice.h>
  28 #include <linux/notifier.h>
  29 #include <linux/reboot.h>
  30 #include <linux/types.h>
  31 #include <linux/watchdog.h>
  32 #include <linux/io.h>
  33 #include <linux/uaccess.h>
  34 #include <linux/atomic.h>
  35 #include <asm/system.h>
  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 bool nowayout = WATCHDOG_NOWAYOUT;
  51 module_param(nowayout, bool, 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                 pr_info("Watchdog timer is now disabled\n");
  69         }
  70 }
  71
  72 static void wdt_enable(void)
  73 {
  74         /* enable the watchdog */
  75         if (!test_and_set_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
  76                 inb_p(SBC7240_ENABLE_PORT);
  77                 pr_info("Watchdog timer is now enabled\n");
  78         }
  79 }
  80
  81 static int wdt_set_timeout(int t)
  82 {
  83         if (t < 1 || t > SBC7240_MAX_TIMEOUT) {
  84                 pr_err("timeout value must be 1<=x<=%d\n", SBC7240_MAX_TIMEOUT);
  85                 return -1;
  86         }
  87         /* set the timeout */
  88         outb_p((unsigned)t, SBC7240_SET_TIMEOUT_PORT);
  89         timeout = t;
  90         pr_info("timeout set to %d seconds\n", t);
  91         return 0;
  92 }
  93
  94 /* Whack the dog */
  95 static inline void wdt_keepalive(void)
  96 {
  97         if (test_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status))
  98                 inb_p(SBC7240_ENABLE_PORT);
  99 }
 100
 101 /*
 102  * /dev/watchdog handling
 103  */
 104 static ssize_t fop_write(struct file *file, const char __user *buf,
 105                          size_t count, loff_t *ppos)
 106 {
 107         size_t i;
 108         char c;
 109
 110         if (count) {
 111                 if (!nowayout) {
 112                         clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
 113                                 &wdt_status);
 114
 115                         /* is there a magic char ? */
 116                         for (i = 0; i != count; i++) {
 117                                 if (get_user(c, buf + i))
 118                                         return -EFAULT;
 119                                 if (c == SBC7240_MAGIC_CHAR) {
 120                                         set_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
 121                                                 &wdt_status);
 122                                         break;
 123                                 }
 124                         }
 125                 }
 126
 127                 wdt_keepalive();
 128         }
 129
 130         return count;
 131 }
 132
 133 static int fop_open(struct inode *inode, struct file *file)
 134 {
 135         if (test_and_set_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status))
 136                 return -EBUSY;
 137
 138         wdt_enable();
 139
 140         return nonseekable_open(inode, file);
 141 }
 142
 143 static int fop_close(struct inode *inode, struct file *file)
 144 {
 145         if (test_and_clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT, &wdt_status)
 146             || !nowayout) {
 147                 wdt_disable();
 148         } else {
 149                 pr_crit("Unexpected close, not stopping watchdog!\n");
 150                 wdt_keepalive();
 151         }
 152
 153         clear_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status);
 154         return 0;
 155 }
 156
 157 static const struct watchdog_info ident = {
 158         .options = WDIOF_KEEPALIVEPING|
 159                    WDIOF_SETTIMEOUT|
 160                    WDIOF_MAGICCLOSE,
 161         .firmware_version = 1,
 162         .identity = "SBC7240",
 163 };
 164
 165
 166 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 167 {
 168         switch (cmd) {
 169         case WDIOC_GETSUPPORT:
 170                 return copy_to_user((void __user *)arg, &ident, sizeof(ident))
 171                                                  ? -EFAULT : 0;
 172         case WDIOC_GETSTATUS:
 173         case WDIOC_GETBOOTSTATUS:
 174                 return put_user(0, (int __user *)arg);
 175         case WDIOC_SETOPTIONS:
 176         {
 177                 int options;
 178                 int retval = -EINVAL;
 179
 180                 if (get_user(options, (int __user *)arg))
 181                         return -EFAULT;
 182
 183                 if (options & WDIOS_DISABLECARD) {
 184                         wdt_disable();
 185                         retval = 0;
 186                 }
 187
 188                 if (options & WDIOS_ENABLECARD) {
 189                         wdt_enable();
 190                         retval = 0;
 191                 }
 192
 193                 return retval;
 194         }
 195         case WDIOC_KEEPALIVE:
 196                 wdt_keepalive();
 197                 return 0;
 198         case WDIOC_SETTIMEOUT:
 199         {
 200                 int new_timeout;
 201
 202                 if (get_user(new_timeout, (int __user *)arg))
 203                         return -EFAULT;
 204
 205                 if (wdt_set_timeout(new_timeout))
 206                         return -EINVAL;
 207
 208                 /* Fall through */
 209         }
 210         case WDIOC_GETTIMEOUT:
 211                 return put_user(timeout, (int __user *)arg);
 212         default:
 213                 return -ENOTTY;
 214         }
 215 }
 216
 217 static const struct file_operations wdt_fops = {
 218         .owner = THIS_MODULE,
 219         .llseek = no_llseek,
 220         .write = fop_write,
 221         .open = fop_open,
 222         .release = fop_close,
 223         .unlocked_ioctl = fop_ioctl,
 224 };
 225
 226 static struct miscdevice wdt_miscdev = {
 227         .minor = WATCHDOG_MINOR,
 228         .name = "watchdog",
 229         .fops = &wdt_fops,
 230 };
 231
 232 /*
 233  *      Notifier for system down
 234  */
 235
 236 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 237                           void *unused)
 238 {
 239         if (code == SYS_DOWN || code == SYS_HALT)
 240                 wdt_disable();
 241         return NOTIFY_DONE;
 242 }
 243
 244 static struct notifier_block wdt_notifier = {
 245         .notifier_call = wdt_notify_sys,
 246 };
 247
 248 static void __exit sbc7240_wdt_unload(void)
 249 {
 250         pr_info("Removing watchdog\n");
 251         misc_deregister(&wdt_miscdev);
 252
 253         unregister_reboot_notifier(&wdt_notifier);
 254         release_region(SBC7240_ENABLE_PORT, 1);
 255 }
 256
 257 static int __init sbc7240_wdt_init(void)
 258 {
 259         int rc = -EBUSY;
 260
 261         if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
 262                 pr_err("I/O address 0x%04x already in use\n",
 263                        SBC7240_ENABLE_PORT);
 264                 rc = -EIO;
 265                 goto err_out;
 266         }
 267
 268         /* The IO port 0x043 used to disable the watchdog
 269          * is already claimed by the system timer, so we
 270          * can't request_region() it ...*/
 271
 272         if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
 273                 timeout = SBC7240_TIMEOUT;
 274                 pr_info("timeout value must be 1<=x<=%d, using %d\n",
 275                         SBC7240_MAX_TIMEOUT, timeout);
 276         }
 277         wdt_set_timeout(timeout);
 278         wdt_disable();
 279
 280         rc = register_reboot_notifier(&wdt_notifier);
 281         if (rc) {
 282                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
 283                 goto err_out_region;
 284         }
 285
 286         rc = misc_register(&wdt_miscdev);
 287         if (rc) {
 288                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 289                        wdt_miscdev.minor, rc);
 290                 goto err_out_reboot_notifier;
 291         }
 292
 293         pr_info("Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
 294                 nowayout);
 295
 296         return 0;
 297
 298 err_out_reboot_notifier:
 299         unregister_reboot_notifier(&wdt_notifier);
 300 err_out_region:
 301         release_region(SBC7240_ENABLE_PORT, 1);
 302 err_out:
 303         return rc;
 304 }
 305
 306 module_init(sbc7240_wdt_init);
 307 module_exit(sbc7240_wdt_unload);
 308
 309 MODULE_AUTHOR("Gilles Gigan");
 310 MODULE_DESCRIPTION("Watchdog device driver for single board"
 311                    " computers EPIC Nano 7240 from iEi");
 312 MODULE_LICENSE("GPL");
 313 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 314