drivers/watchdog/geodewdt.c

   1 /* Watchdog timer for the Geode GX/LX with the CS5535/CS5536 companion chip
   2  *
   3  * Copyright (C) 2006-2007, Advanced Micro Devices, Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; either version
   8  * 2 of the License, or (at your option) any later version.
   9  */
  10
  11
  12 #include <linux/module.h>
  13 #include <linux/moduleparam.h>
  14 #include <linux/types.h>
  15 #include <linux/miscdevice.h>
  16 #include <linux/watchdog.h>
  17 #include <linux/fs.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/reboot.h>
  20 #include <linux/uaccess.h>
  21
  22 #include <asm/geode.h>
  23
  24 #define GEODEWDT_HZ 500
  25 #define GEODEWDT_SCALE 6
  26 #define GEODEWDT_MAX_SECONDS 131
  27
  28 #define WDT_FLAGS_OPEN 1
  29 #define WDT_FLAGS_ORPHAN 2
  30
  31 #define DRV_NAME "geodewdt"
  32 #define WATCHDOG_NAME "Geode GX/LX WDT"
  33 #define WATCHDOG_TIMEOUT 60
  34
  35 static int timeout = WATCHDOG_TIMEOUT;
  36 module_param(timeout, int, 0);
  37 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. 1<= timeout <=131, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
  38
  39 static int nowayout = WATCHDOG_NOWAYOUT;
  40 module_param(nowayout, int, 0);
  41 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  42
  43 static struct platform_device *geodewdt_platform_device;
  44 static unsigned long wdt_flags;
  45 static int wdt_timer;
  46 static int safe_close;
  47
  48 static void geodewdt_ping(void)
  49 {
  50         /* Stop the counter */
  51         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  52
  53         /* Reset the counter */
  54         geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  55
  56         /* Enable the counter */
  57         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
  58 }
  59
  60 static void geodewdt_disable(void)
  61 {
  62         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  63         geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  64 }
  65
  66 static int geodewdt_set_heartbeat(int val)
  67 {
  68         if (val < 1 || val > GEODEWDT_MAX_SECONDS)
  69                 return -EINVAL;
  70
  71         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  72         geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ);
  73         geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  74         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
  75
  76         timeout = val;
  77         return 0;
  78 }
  79
  80 static int geodewdt_open(struct inode *inode, struct file *file)
  81 {
  82         if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags))
  83                 return -EBUSY;
  84
  85         if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags))
  86                 __module_get(THIS_MODULE);
  87
  88         geodewdt_ping();
  89         return nonseekable_open(inode, file);
  90 }
  91
  92 static int geodewdt_release(struct inode *inode, struct file *file)
  93 {
  94         if (safe_close) {
  95                 geodewdt_disable();
  96                 module_put(THIS_MODULE);
  97         } else {
  98                 printk(KERN_CRIT "Unexpected close - watchdog is not stopping.\n");
  99                 geodewdt_ping();
 100
 101                 set_bit(WDT_FLAGS_ORPHAN, &wdt_flags);
 102         }
 103
 104         clear_bit(WDT_FLAGS_OPEN, &wdt_flags);
 105         safe_close = 0;
 106         return 0;
 107 }
 108
 109 static ssize_t geodewdt_write(struct file *file, const char __user *data,
 110                                 size_t len, loff_t *ppos)
 111 {
 112         if (len) {
 113                 if (!nowayout) {
 114                         size_t i;
 115                         safe_close = 0;
 116
 117                         for (i = 0; i != len; i++) {
 118                                 char c;
 119
 120                                 if (get_user(c, data + i))
 121                                         return -EFAULT;
 122
 123                                 if (c == 'V')
 124                                         safe_close = 1;
 125                         }
 126                 }
 127
 128                 geodewdt_ping();
 129         }
 130         return len;
 131 }
 132
 133 static long geodewdt_ioctl(struct file *file, unsigned int cmd,
 134                                 unsigned long arg)
 135 {
 136         void __user *argp = (void __user *)arg;
 137         int __user *p = argp;
 138         int interval;
 139
 140         static struct watchdog_info ident = {
 141                 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
 142                 | WDIOF_MAGICCLOSE,
 143                 .firmware_version =     1,
 144                 .identity =             WATCHDOG_NAME,
 145         };
 146
 147         switch (cmd) {
 148         case WDIOC_GETSUPPORT:
 149                 return copy_to_user(argp, &ident,
 150                                     sizeof(ident)) ? -EFAULT : 0;
 151                 break;
 152
 153         case WDIOC_GETSTATUS:
 154         case WDIOC_GETBOOTSTATUS:
 155                 return put_user(0, p);
 156
 157         case WDIOC_SETOPTIONS:
 158         {
 159                 int options, ret = -EINVAL;
 160
 161                 if (get_user(options, p))
 162                         return -EFAULT;
 163
 164                 if (options & WDIOS_DISABLECARD) {
 165                         geodewdt_disable();
 166                         ret = 0;
 167                 }
 168
 169                 if (options & WDIOS_ENABLECARD) {
 170                         geodewdt_ping();
 171                         ret = 0;
 172                 }
 173
 174                 return ret;
 175         }
 176         case WDIOC_KEEPALIVE:
 177                 geodewdt_ping();
 178                 return 0;
 179
 180         case WDIOC_SETTIMEOUT:
 181                 if (get_user(interval, p))
 182                         return -EFAULT;
 183
 184                 if (geodewdt_set_heartbeat(interval))
 185                         return -EINVAL;
 186         /* Fall through */
 187         case WDIOC_GETTIMEOUT:
 188                 return put_user(timeout, p);
 189
 190         default:
 191                 return -ENOTTY;
 192         }
 193
 194         return 0;
 195 }
 196
 197 static const struct file_operations geodewdt_fops = {
 198         .owner          = THIS_MODULE,
 199         .llseek         = no_llseek,
 200         .write          = geodewdt_write,
 201         .unlocked_ioctl = geodewdt_ioctl,
 202         .open           = geodewdt_open,
 203         .release        = geodewdt_release,
 204 };
 205
 206 static struct miscdevice geodewdt_miscdev = {
 207         .minor = WATCHDOG_MINOR,
 208         .name = "watchdog",
 209         .fops = &geodewdt_fops,
 210 };
 211
 212 static int __devinit geodewdt_probe(struct platform_device *dev)
 213 {
 214         int ret, timer;
 215
 216         timer = geode_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
 217
 218         if (timer == -1) {
 219                 printk(KERN_ERR "geodewdt:  No timers were available\n");
 220                 return -ENODEV;
 221         }
 222
 223         wdt_timer = timer;
 224
 225         /* Set up the timer */
 226
 227         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP,
 228                           GEODEWDT_SCALE | (3 << 8));
 229
 230         /* Set up comparator 2 to reset when the event fires */
 231         geode_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);
 232
 233         /* Set up the initial timeout */
 234
 235         geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,
 236                 timeout * GEODEWDT_HZ);
 237
 238         ret = misc_register(&geodewdt_miscdev);
 239
 240         return ret;
 241 }
 242
 243 static int __devexit geodewdt_remove(struct platform_device *dev)
 244 {
 245         misc_deregister(&geodewdt_miscdev);
 246         return 0;
 247 }
 248
 249 static void geodewdt_shutdown(struct platform_device *dev)
 250 {
 251         geodewdt_disable();
 252 }
 253
 254 static struct platform_driver geodewdt_driver = {
 255         .probe          = geodewdt_probe,
 256         .remove         = __devexit_p(geodewdt_remove),
 257         .shutdown       = geodewdt_shutdown,
 258         .driver         = {
 259                 .owner  = THIS_MODULE,
 260                 .name   = DRV_NAME,
 261         },
 262 };
 263
 264 static int __init geodewdt_init(void)
 265 {
 266         int ret;
 267
 268         ret = platform_driver_register(&geodewdt_driver);
 269         if (ret)
 270                 return ret;
 271
 272         geodewdt_platform_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0);
 273         if (IS_ERR(geodewdt_platform_device)) {
 274                 ret = PTR_ERR(geodewdt_platform_device);
 275                 goto err;
 276         }
 277
 278         return 0;
 279 err:
 280         platform_driver_unregister(&geodewdt_driver);
 281         return ret;
 282 }
 283
 284 static void __exit geodewdt_exit(void)
 285 {
 286         platform_device_unregister(geodewdt_platform_device);
 287         platform_driver_unregister(&geodewdt_driver);
 288 }
 289
 290 module_init(geodewdt_init);
 291 module_exit(geodewdt_exit);
 292
 293 MODULE_AUTHOR("Advanced Micro Devices, Inc");
 294 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");
 295 MODULE_LICENSE("GPL");
 296 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);