drivers/watchdog/sbc7240_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *      NANO7240 SBC Watchdog device driver
   4  *
   5  *      Based on w83877f.c by Scott Jennings,
   6  *
   7  *      (c) Copyright 2007  Gilles GIGAN <gilles.gigan@jcu.edu.au>
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/fs.h>
  13 #include <linux/init.h>
  14 #include <linux/ioport.h>
  15 #include <linux/jiffies.h>
  16 #include <linux/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/notifier.h>
  20 #include <linux/reboot.h>
  21 #include <linux/types.h>
  22 #include <linux/watchdog.h>
  23 #include <linux/io.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/atomic.h>
  26
  27 #define SBC7240_ENABLE_PORT             0x443
  28 #define SBC7240_DISABLE_PORT            0x043
  29 #define SBC7240_SET_TIMEOUT_PORT        SBC7240_ENABLE_PORT
  30 #define SBC7240_MAGIC_CHAR              'V'
  31
  32 #define SBC7240_TIMEOUT         30
  33 #define SBC7240_MAX_TIMEOUT             255
  34 static int timeout = SBC7240_TIMEOUT;   /* in seconds */
  35 module_param(timeout, int, 0);
  36 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<="
  37                  __MODULE_STRING(SBC7240_MAX_TIMEOUT) ", default="
  38                  __MODULE_STRING(SBC7240_TIMEOUT) ")");
  39
  40 static bool nowayout = WATCHDOG_NOWAYOUT;
  41 module_param(nowayout, bool, 0);
  42 MODULE_PARM_DESC(nowayout, "Disable watchdog when closing device file");
  43
  44 #define SBC7240_OPEN_STATUS_BIT         0
  45 #define SBC7240_ENABLED_STATUS_BIT      1
  46 #define SBC7240_EXPECT_CLOSE_STATUS_BIT 2
  47 static unsigned long wdt_status;
  48
  49 /*
  50  * Utility routines
  51  */
  52
  53 static void wdt_disable(void)
  54 {
  55         /* disable the watchdog */
  56         if (test_and_clear_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
  57                 inb_p(SBC7240_DISABLE_PORT);
  58                 pr_info("Watchdog timer is now disabled\n");
  59         }
  60 }
  61
  62 static void wdt_enable(void)
  63 {
  64         /* enable the watchdog */
  65         if (!test_and_set_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
  66                 inb_p(SBC7240_ENABLE_PORT);
  67                 pr_info("Watchdog timer is now enabled\n");
  68         }
  69 }
  70
  71 static int wdt_set_timeout(int t)
  72 {
  73         if (t < 1 || t > SBC7240_MAX_TIMEOUT) {
  74                 pr_err("timeout value must be 1<=x<=%d\n", SBC7240_MAX_TIMEOUT);
  75                 return -1;
  76         }
  77         /* set the timeout */
  78         outb_p((unsigned)t, SBC7240_SET_TIMEOUT_PORT);
  79         timeout = t;
  80         pr_info("timeout set to %d seconds\n", t);
  81         return 0;
  82 }
  83
  84 /* Whack the dog */
  85 static inline void wdt_keepalive(void)
  86 {
  87         if (test_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status))
  88                 inb_p(SBC7240_ENABLE_PORT);
  89 }
  90
  91 /*
  92  * /dev/watchdog handling
  93  */
  94 static ssize_t fop_write(struct file *file, const char __user *buf,
  95                          size_t count, loff_t *ppos)
  96 {
  97         size_t i;
  98         char c;
  99
 100         if (count) {
 101                 if (!nowayout) {
 102                         clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
 103                                 &wdt_status);
 104
 105                         /* is there a magic char ? */
 106                         for (i = 0; i != count; i++) {
 107                                 if (get_user(c, buf + i))
 108                                         return -EFAULT;
 109                                 if (c == SBC7240_MAGIC_CHAR) {
 110                                         set_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
 111                                                 &wdt_status);
 112                                         break;
 113                                 }
 114                         }
 115                 }
 116
 117                 wdt_keepalive();
 118         }
 119
 120         return count;
 121 }
 122
 123 static int fop_open(struct inode *inode, struct file *file)
 124 {
 125         if (test_and_set_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status))
 126                 return -EBUSY;
 127
 128         wdt_enable();
 129
 130         return stream_open(inode, file);
 131 }
 132
 133 static int fop_close(struct inode *inode, struct file *file)
 134 {
 135         if (test_and_clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT, &wdt_status)
 136             || !nowayout) {
 137                 wdt_disable();
 138         } else {
 139                 pr_crit("Unexpected close, not stopping watchdog!\n");
 140                 wdt_keepalive();
 141         }
 142
 143         clear_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status);
 144         return 0;
 145 }
 146
 147 static const struct watchdog_info ident = {
 148         .options = WDIOF_KEEPALIVEPING|
 149                    WDIOF_SETTIMEOUT|
 150                    WDIOF_MAGICCLOSE,
 151         .firmware_version = 1,
 152         .identity = "SBC7240",
 153 };
 154
 155
 156 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 157 {
 158         switch (cmd) {
 159         case WDIOC_GETSUPPORT:
 160                 return copy_to_user((void __user *)arg, &ident, sizeof(ident))
 161                                                  ? -EFAULT : 0;
 162         case WDIOC_GETSTATUS:
 163         case WDIOC_GETBOOTSTATUS:
 164                 return put_user(0, (int __user *)arg);
 165         case WDIOC_SETOPTIONS:
 166         {
 167                 int options;
 168                 int retval = -EINVAL;
 169
 170                 if (get_user(options, (int __user *)arg))
 171                         return -EFAULT;
 172
 173                 if (options & WDIOS_DISABLECARD) {
 174                         wdt_disable();
 175                         retval = 0;
 176                 }
 177
 178                 if (options & WDIOS_ENABLECARD) {
 179                         wdt_enable();
 180                         retval = 0;
 181                 }
 182
 183                 return retval;
 184         }
 185         case WDIOC_KEEPALIVE:
 186                 wdt_keepalive();
 187                 return 0;
 188         case WDIOC_SETTIMEOUT:
 189         {
 190                 int new_timeout;
 191
 192                 if (get_user(new_timeout, (int __user *)arg))
 193                         return -EFAULT;
 194
 195                 if (wdt_set_timeout(new_timeout))
 196                         return -EINVAL;
 197         }
 198                 fallthrough;
 199         case WDIOC_GETTIMEOUT:
 200                 return put_user(timeout, (int __user *)arg);
 201         default:
 202                 return -ENOTTY;
 203         }
 204 }
 205
 206 static const struct file_operations wdt_fops = {
 207         .owner = THIS_MODULE,
 208         .llseek = no_llseek,
 209         .write = fop_write,
 210         .open = fop_open,
 211         .release = fop_close,
 212         .unlocked_ioctl = fop_ioctl,
 213         .compat_ioctl = compat_ptr_ioctl,
 214 };
 215
 216 static struct miscdevice wdt_miscdev = {
 217         .minor = WATCHDOG_MINOR,
 218         .name = "watchdog",
 219         .fops = &wdt_fops,
 220 };
 221
 222 /*
 223  *      Notifier for system down
 224  */
 225
 226 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 227                           void *unused)
 228 {
 229         if (code == SYS_DOWN || code == SYS_HALT)
 230                 wdt_disable();
 231         return NOTIFY_DONE;
 232 }
 233
 234 static struct notifier_block wdt_notifier = {
 235         .notifier_call = wdt_notify_sys,
 236 };
 237
 238 static void __exit sbc7240_wdt_unload(void)
 239 {
 240         pr_info("Removing watchdog\n");
 241         misc_deregister(&wdt_miscdev);
 242
 243         unregister_reboot_notifier(&wdt_notifier);
 244         release_region(SBC7240_ENABLE_PORT, 1);
 245 }
 246
 247 static int __init sbc7240_wdt_init(void)
 248 {
 249         int rc = -EBUSY;
 250
 251         if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
 252                 pr_err("I/O address 0x%04x already in use\n",
 253                        SBC7240_ENABLE_PORT);
 254                 rc = -EIO;
 255                 goto err_out;
 256         }
 257
 258         /* The IO port 0x043 used to disable the watchdog
 259          * is already claimed by the system timer, so we
 260          * can't request_region() it ...*/
 261
 262         if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
 263                 timeout = SBC7240_TIMEOUT;
 264                 pr_info("timeout value must be 1<=x<=%d, using %d\n",
 265                         SBC7240_MAX_TIMEOUT, timeout);
 266         }
 267         wdt_set_timeout(timeout);
 268         wdt_disable();
 269
 270         rc = register_reboot_notifier(&wdt_notifier);
 271         if (rc) {
 272                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
 273                 goto err_out_region;
 274         }
 275
 276         rc = misc_register(&wdt_miscdev);
 277         if (rc) {
 278                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 279                        wdt_miscdev.minor, rc);
 280                 goto err_out_reboot_notifier;
 281         }
 282
 283         pr_info("Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
 284                 nowayout);
 285
 286         return 0;
 287
 288 err_out_reboot_notifier:
 289         unregister_reboot_notifier(&wdt_notifier);
 290 err_out_region:
 291         release_region(SBC7240_ENABLE_PORT, 1);
 292 err_out:
 293         return rc;
 294 }
 295
 296 module_init(sbc7240_wdt_init);
 297 module_exit(sbc7240_wdt_unload);
 298
 299 MODULE_AUTHOR("Gilles Gigan");
 300 MODULE_DESCRIPTION("Watchdog device driver for single board"
 301                    " computers EPIC Nano 7240 from iEi");
 302 MODULE_LICENSE("GPL");