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
  36 #define SBC7240_ENABLE_PORT             0x443
  37 #define SBC7240_DISABLE_PORT            0x043
  38 #define SBC7240_SET_TIMEOUT_PORT        SBC7240_ENABLE_PORT
  39 #define SBC7240_MAGIC_CHAR              'V'
  40
  41 #define SBC7240_TIMEOUT         30
  42 #define SBC7240_MAX_TIMEOUT             255
  43 static int timeout = SBC7240_TIMEOUT;   /* in seconds */
  44 module_param(timeout, int, 0);
  45 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<="
  46                  __MODULE_STRING(SBC7240_MAX_TIMEOUT) ", default="
  47                  __MODULE_STRING(SBC7240_TIMEOUT) ")");
  48
  49 static bool nowayout = WATCHDOG_NOWAYOUT;
  50 module_param(nowayout, bool, 0);
  51 MODULE_PARM_DESC(nowayout, "Disable watchdog when closing device file");
  52
  53 #define SBC7240_OPEN_STATUS_BIT         0
  54 #define SBC7240_ENABLED_STATUS_BIT      1
  55 #define SBC7240_EXPECT_CLOSE_STATUS_BIT 2
  56 static unsigned long wdt_status;
  57
  58 /*
  59  * Utility routines
  60  */
  61
  62 static void wdt_disable(void)
  63 {
  64         /* disable the watchdog */
  65         if (test_and_clear_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
  66                 inb_p(SBC7240_DISABLE_PORT);
  67                 pr_info("Watchdog timer is now disabled\n");
  68         }
  69 }
  70
  71 static void wdt_enable(void)
  72 {
  73         /* enable the watchdog */
  74         if (!test_and_set_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
  75                 inb_p(SBC7240_ENABLE_PORT);
  76                 pr_info("Watchdog timer is now enabled\n");
  77         }
  78 }
  79
  80 static int wdt_set_timeout(int t)
  81 {
  82         if (t < 1 || t > SBC7240_MAX_TIMEOUT) {
  83                 pr_err("timeout value must be 1<=x<=%d\n", SBC7240_MAX_TIMEOUT);
  84                 return -1;
  85         }
  86         /* set the timeout */
  87         outb_p((unsigned)t, SBC7240_SET_TIMEOUT_PORT);
  88         timeout = t;
  89         pr_info("timeout set to %d seconds\n", t);
  90         return 0;
  91 }
  92
  93 /* Whack the dog */
  94 static inline void wdt_keepalive(void)
  95 {
  96         if (test_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status))
  97                 inb_p(SBC7240_ENABLE_PORT);
  98 }
  99
 100 /*
 101  * /dev/watchdog handling
 102  */
 103 static ssize_t fop_write(struct file *file, const char __user *buf,
 104                          size_t count, loff_t *ppos)
 105 {
 106         size_t i;
 107         char c;
 108
 109         if (count) {
 110                 if (!nowayout) {
 111                         clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
 112                                 &wdt_status);
 113
 114                         /* is there a magic char ? */
 115                         for (i = 0; i != count; i++) {
 116                                 if (get_user(c, buf + i))
 117                                         return -EFAULT;
 118                                 if (c == SBC7240_MAGIC_CHAR) {
 119                                         set_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
 120                                                 &wdt_status);
 121                                         break;
 122                                 }
 123                         }
 124                 }
 125
 126                 wdt_keepalive();
 127         }
 128
 129         return count;
 130 }
 131
 132 static int fop_open(struct inode *inode, struct file *file)
 133 {
 134         if (test_and_set_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status))
 135                 return -EBUSY;
 136
 137         wdt_enable();
 138
 139         return nonseekable_open(inode, file);
 140 }
 141
 142 static int fop_close(struct inode *inode, struct file *file)
 143 {
 144         if (test_and_clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT, &wdt_status)
 145             || !nowayout) {
 146                 wdt_disable();
 147         } else {
 148                 pr_crit("Unexpected close, not stopping watchdog!\n");
 149                 wdt_keepalive();
 150         }
 151
 152         clear_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status);
 153         return 0;
 154 }
 155
 156 static const struct watchdog_info ident = {
 157         .options = WDIOF_KEEPALIVEPING|
 158                    WDIOF_SETTIMEOUT|
 159                    WDIOF_MAGICCLOSE,
 160         .firmware_version = 1,
 161         .identity = "SBC7240",
 162 };
 163
 164
 165 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 166 {
 167         switch (cmd) {
 168         case WDIOC_GETSUPPORT:
 169                 return copy_to_user((void __user *)arg, &ident, sizeof(ident))
 170                                                  ? -EFAULT : 0;
 171         case WDIOC_GETSTATUS:
 172         case WDIOC_GETBOOTSTATUS:
 173                 return put_user(0, (int __user *)arg);
 174         case WDIOC_SETOPTIONS:
 175         {
 176                 int options;
 177                 int retval = -EINVAL;
 178
 179                 if (get_user(options, (int __user *)arg))
 180                         return -EFAULT;
 181
 182                 if (options & WDIOS_DISABLECARD) {
 183                         wdt_disable();
 184                         retval = 0;
 185                 }
 186
 187                 if (options & WDIOS_ENABLECARD) {
 188                         wdt_enable();
 189                         retval = 0;
 190                 }
 191
 192                 return retval;
 193         }
 194         case WDIOC_KEEPALIVE:
 195                 wdt_keepalive();
 196                 return 0;
 197         case WDIOC_SETTIMEOUT:
 198         {
 199                 int new_timeout;
 200
 201                 if (get_user(new_timeout, (int __user *)arg))
 202                         return -EFAULT;
 203
 204                 if (wdt_set_timeout(new_timeout))
 205                         return -EINVAL;
 206
 207                 /* Fall through */
 208         }
 209         case WDIOC_GETTIMEOUT:
 210                 return put_user(timeout, (int __user *)arg);
 211         default:
 212                 return -ENOTTY;
 213         }
 214 }
 215
 216 static const struct file_operations wdt_fops = {
 217         .owner = THIS_MODULE,
 218         .llseek = no_llseek,
 219         .write = fop_write,
 220         .open = fop_open,
 221         .release = fop_close,
 222         .unlocked_ioctl = fop_ioctl,
 223 };
 224
 225 static struct miscdevice wdt_miscdev = {
 226         .minor = WATCHDOG_MINOR,
 227         .name = "watchdog",
 228         .fops = &wdt_fops,
 229 };
 230
 231 /*
 232  *      Notifier for system down
 233  */
 234
 235 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 236                           void *unused)
 237 {
 238         if (code == SYS_DOWN || code == SYS_HALT)
 239                 wdt_disable();
 240         return NOTIFY_DONE;
 241 }
 242
 243 static struct notifier_block wdt_notifier = {
 244         .notifier_call = wdt_notify_sys,
 245 };
 246
 247 static void __exit sbc7240_wdt_unload(void)
 248 {
 249         pr_info("Removing watchdog\n");
 250         misc_deregister(&wdt_miscdev);
 251
 252         unregister_reboot_notifier(&wdt_notifier);
 253         release_region(SBC7240_ENABLE_PORT, 1);
 254 }
 255
 256 static int __init sbc7240_wdt_init(void)
 257 {
 258         int rc = -EBUSY;
 259
 260         if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
 261                 pr_err("I/O address 0x%04x already in use\n",
 262                        SBC7240_ENABLE_PORT);
 263                 rc = -EIO;
 264                 goto err_out;
 265         }
 266
 267         /* The IO port 0x043 used to disable the watchdog
 268          * is already claimed by the system timer, so we
 269          * can't request_region() it ...*/
 270
 271         if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
 272                 timeout = SBC7240_TIMEOUT;
 273                 pr_info("timeout value must be 1<=x<=%d, using %d\n",
 274                         SBC7240_MAX_TIMEOUT, timeout);
 275         }
 276         wdt_set_timeout(timeout);
 277         wdt_disable();
 278
 279         rc = register_reboot_notifier(&wdt_notifier);
 280         if (rc) {
 281                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
 282                 goto err_out_region;
 283         }
 284
 285         rc = misc_register(&wdt_miscdev);
 286         if (rc) {
 287                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 288                        wdt_miscdev.minor, rc);
 289                 goto err_out_reboot_notifier;
 290         }
 291
 292         pr_info("Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
 293                 nowayout);
 294
 295         return 0;
 296
 297 err_out_reboot_notifier:
 298         unregister_reboot_notifier(&wdt_notifier);
 299 err_out_region:
 300         release_region(SBC7240_ENABLE_PORT, 1);
 301 err_out:
 302         return rc;
 303 }
 304
 305 module_init(sbc7240_wdt_init);
 306 module_exit(sbc7240_wdt_unload);
 307
 308 MODULE_AUTHOR("Gilles Gigan");
 309 MODULE_DESCRIPTION("Watchdog device driver for single board"
 310                    " computers EPIC Nano 7240 from iEi");
 311 MODULE_LICENSE("GPL");