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
  21 #include <asm/uaccess.h>
  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
  81 geodewdt_open(struct inode *inode, struct file *file)
  82 {
  83         if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags))
  84                 return -EBUSY;
  85
  86         if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags))
  87                 __module_get(THIS_MODULE);
  88
  89         geodewdt_ping();
  90         return nonseekable_open(inode, file);
  91 }
  92
  93 static int
  94 geodewdt_release(struct inode *inode, struct file *file)
  95 {
  96         if (safe_close) {
  97                 geodewdt_disable();
  98                 module_put(THIS_MODULE);
  99         }
 100         else {
 101                 printk(KERN_CRIT "Unexpected close - watchdog is not stopping.\n");
 102                 geodewdt_ping();
 103
 104                 set_bit(WDT_FLAGS_ORPHAN, &wdt_flags);
 105         }
 106
 107         clear_bit(WDT_FLAGS_OPEN, &wdt_flags);
 108         safe_close = 0;
 109         return 0;
 110 }
 111
 112 static ssize_t
 113 geodewdt_write(struct file *file, const char __user *data, size_t len,
 114                loff_t *ppos)
 115 {
 116         if(len) {
 117                 if (!nowayout) {
 118                         size_t i;
 119                         safe_close = 0;
 120
 121                         for (i = 0; i != len; i++) {
 122                                 char c;
 123
 124                                 if (get_user(c, data + i))
 125                                         return -EFAULT;
 126
 127                                 if (c == 'V')
 128                                         safe_close = 1;
 129                         }
 130                 }
 131
 132                 geodewdt_ping();
 133         }
 134         return len;
 135 }
 136
 137 static int
 138 geodewdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 139                unsigned long arg)
 140 {
 141         void __user *argp = (void __user *)arg;
 142         int __user *p = argp;
 143         int interval;
 144
 145         static struct watchdog_info ident = {
 146                 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
 147                 | WDIOF_MAGICCLOSE,
 148                 .firmware_version =     1,
 149                 .identity =             WATCHDOG_NAME,
 150         };
 151
 152         switch(cmd) {
 153         case WDIOC_GETSUPPORT:
 154                 return copy_to_user(argp, &ident,
 155                                     sizeof(ident)) ? -EFAULT : 0;
 156                 break;
 157
 158         case WDIOC_GETSTATUS:
 159         case WDIOC_GETBOOTSTATUS:
 160                 return put_user(0, p);
 161
 162         case WDIOC_KEEPALIVE:
 163                 geodewdt_ping();
 164                 return 0;
 165
 166         case WDIOC_SETTIMEOUT:
 167                 if (get_user(interval, p))
 168                         return -EFAULT;
 169
 170                 if (geodewdt_set_heartbeat(interval))
 171                         return -EINVAL;
 172
 173 /* Fall through */
 174
 175         case WDIOC_GETTIMEOUT:
 176                 return put_user(timeout, p);
 177
 178         case WDIOC_SETOPTIONS:
 179         {
 180                 int options, ret = -EINVAL;
 181
 182                 if (get_user(options, p))
 183                         return -EFAULT;
 184
 185                 if (options & WDIOS_DISABLECARD) {
 186                         geodewdt_disable();
 187                         ret = 0;
 188                 }
 189
 190                 if (options & WDIOS_ENABLECARD) {
 191                         geodewdt_ping();
 192                         ret = 0;
 193                 }
 194
 195                 return ret;
 196         }
 197         default:
 198                 return -ENOTTY;
 199         }
 200
 201         return 0;
 202 }
 203
 204 static const struct file_operations geodewdt_fops = {
 205         .owner          = THIS_MODULE,
 206         .llseek         = no_llseek,
 207         .write          = geodewdt_write,
 208         .ioctl          = geodewdt_ioctl,
 209         .open           = geodewdt_open,
 210         .release        = geodewdt_release,
 211 };
 212
 213 static struct miscdevice geodewdt_miscdev = {
 214         .minor = WATCHDOG_MINOR,
 215         .name = "watchdog",
 216         .fops = &geodewdt_fops
 217 };
 218
 219 static int __devinit
 220 geodewdt_probe(struct platform_device *dev)
 221 {
 222         int ret, timer;
 223
 224         timer = geode_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
 225
 226         if (timer == -1) {
 227                 printk(KERN_ERR "geodewdt:  No timers were available\n");
 228                 return -ENODEV;
 229         }
 230
 231         wdt_timer = timer;
 232
 233         /* Set up the timer */
 234
 235         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP,
 236                           GEODEWDT_SCALE | (3 << 8));
 237
 238         /* Set up comparator 2 to reset when the event fires */
 239         geode_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);
 240
 241         /* Set up the initial timeout */
 242
 243         geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,
 244                 timeout * GEODEWDT_HZ);
 245
 246         ret = misc_register(&geodewdt_miscdev);
 247
 248         return ret;
 249 }
 250
 251 static int __devexit
 252 geodewdt_remove(struct platform_device *dev)
 253 {
 254         misc_deregister(&geodewdt_miscdev);
 255         return 0;
 256 }
 257
 258 static void
 259 geodewdt_shutdown(struct platform_device *dev)
 260 {
 261         geodewdt_disable();
 262 }
 263
 264 static struct platform_driver geodewdt_driver = {
 265         .probe          = geodewdt_probe,
 266         .remove         = __devexit_p(geodewdt_remove),
 267         .shutdown       = geodewdt_shutdown,
 268         .driver         = {
 269                 .owner  = THIS_MODULE,
 270                 .name   = DRV_NAME,
 271         },
 272 };
 273
 274 static int __init
 275 geodewdt_init(void)
 276 {
 277         int ret;
 278
 279         ret = platform_driver_register(&geodewdt_driver);
 280         if (ret)
 281                 return ret;
 282
 283         geodewdt_platform_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0);
 284         if (IS_ERR(geodewdt_platform_device)) {
 285                 ret = PTR_ERR(geodewdt_platform_device);
 286                 goto err;
 287         }
 288
 289         return 0;
 290 err:
 291         platform_driver_unregister(&geodewdt_driver);
 292         return ret;
 293 }
 294
 295 static void __exit
 296 geodewdt_exit(void)
 297 {
 298         platform_device_unregister(geodewdt_platform_device);
 299         platform_driver_unregister(&geodewdt_driver);
 300 }
 301
 302 module_init(geodewdt_init);
 303 module_exit(geodewdt_exit);
 304
 305 MODULE_AUTHOR("Advanced Micro Devices, Inc");
 306 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");
 307 MODULE_LICENSE("GPL");
 308 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);