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,
  38         "Watchdog timeout in seconds. 1<= timeout <=131, default="
  39                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
  40
  41 static int nowayout = WATCHDOG_NOWAYOUT;
  42 module_param(nowayout, int, 0);
  43 MODULE_PARM_DESC(nowayout,
  44         "Watchdog cannot be stopped once started (default="
  45                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  46
  47 static struct platform_device *geodewdt_platform_device;
  48 static unsigned long wdt_flags;
  49 static int wdt_timer;
  50 static int safe_close;
  51
  52 static void geodewdt_ping(void)
  53 {
  54         /* Stop the counter */
  55         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  56
  57         /* Reset the counter */
  58         geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  59
  60         /* Enable the counter */
  61         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
  62 }
  63
  64 static void geodewdt_disable(void)
  65 {
  66         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  67         geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  68 }
  69
  70 static int geodewdt_set_heartbeat(int val)
  71 {
  72         if (val < 1 || val > GEODEWDT_MAX_SECONDS)
  73                 return -EINVAL;
  74
  75         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  76         geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ);
  77         geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  78         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
  79
  80         timeout = val;
  81         return 0;
  82 }
  83
  84 static int geodewdt_open(struct inode *inode, struct file *file)
  85 {
  86         if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags))
  87                 return -EBUSY;
  88
  89         if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags))
  90                 __module_get(THIS_MODULE);
  91
  92         geodewdt_ping();
  93         return nonseekable_open(inode, file);
  94 }
  95
  96 static int geodewdt_release(struct inode *inode, struct file *file)
  97 {
  98         if (safe_close) {
  99                 geodewdt_disable();
 100                 module_put(THIS_MODULE);
 101         } else {
 102                 printk(KERN_CRIT "Unexpected close - watchdog is not stopping.\n");
 103                 geodewdt_ping();
 104
 105                 set_bit(WDT_FLAGS_ORPHAN, &wdt_flags);
 106         }
 107
 108         clear_bit(WDT_FLAGS_OPEN, &wdt_flags);
 109         safe_close = 0;
 110         return 0;
 111 }
 112
 113 static ssize_t geodewdt_write(struct file *file, const char __user *data,
 114                                 size_t len, 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 long geodewdt_ioctl(struct file *file, unsigned int cmd,
 138                                 unsigned long arg)
 139 {
 140         void __user *argp = (void __user *)arg;
 141         int __user *p = argp;
 142         int interval;
 143
 144         static struct watchdog_info ident = {
 145                 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
 146                 | WDIOF_MAGICCLOSE,
 147                 .firmware_version =     1,
 148                 .identity =             WATCHDOG_NAME,
 149         };
 150
 151         switch (cmd) {
 152         case WDIOC_GETSUPPORT:
 153                 return copy_to_user(argp, &ident,
 154                                     sizeof(ident)) ? -EFAULT : 0;
 155                 break;
 156
 157         case WDIOC_GETSTATUS:
 158         case WDIOC_GETBOOTSTATUS:
 159                 return put_user(0, p);
 160
 161         case WDIOC_SETOPTIONS:
 162         {
 163                 int options, ret = -EINVAL;
 164
 165                 if (get_user(options, p))
 166                         return -EFAULT;
 167
 168                 if (options & WDIOS_DISABLECARD) {
 169                         geodewdt_disable();
 170                         ret = 0;
 171                 }
 172
 173                 if (options & WDIOS_ENABLECARD) {
 174                         geodewdt_ping();
 175                         ret = 0;
 176                 }
 177
 178                 return ret;
 179         }
 180         case WDIOC_KEEPALIVE:
 181                 geodewdt_ping();
 182                 return 0;
 183
 184         case WDIOC_SETTIMEOUT:
 185                 if (get_user(interval, p))
 186                         return -EFAULT;
 187
 188                 if (geodewdt_set_heartbeat(interval))
 189                         return -EINVAL;
 190         /* Fall through */
 191         case WDIOC_GETTIMEOUT:
 192                 return put_user(timeout, p);
 193
 194         default:
 195                 return -ENOTTY;
 196         }
 197
 198         return 0;
 199 }
 200
 201 static const struct file_operations geodewdt_fops = {
 202         .owner          = THIS_MODULE,
 203         .llseek         = no_llseek,
 204         .write          = geodewdt_write,
 205         .unlocked_ioctl = geodewdt_ioctl,
 206         .open           = geodewdt_open,
 207         .release        = geodewdt_release,
 208 };
 209
 210 static struct miscdevice geodewdt_miscdev = {
 211         .minor = WATCHDOG_MINOR,
 212         .name = "watchdog",
 213         .fops = &geodewdt_fops,
 214 };
 215
 216 static int __devinit geodewdt_probe(struct platform_device *dev)
 217 {
 218         int ret, timer;
 219
 220         timer = geode_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
 221
 222         if (timer == -1) {
 223                 printk(KERN_ERR "geodewdt:  No timers were available\n");
 224                 return -ENODEV;
 225         }
 226
 227         wdt_timer = timer;
 228
 229         /* Set up the timer */
 230
 231         geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP,
 232                           GEODEWDT_SCALE | (3 << 8));
 233
 234         /* Set up comparator 2 to reset when the event fires */
 235         geode_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);
 236
 237         /* Set up the initial timeout */
 238
 239         geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,
 240                 timeout * GEODEWDT_HZ);
 241
 242         ret = misc_register(&geodewdt_miscdev);
 243
 244         return ret;
 245 }
 246
 247 static int __devexit geodewdt_remove(struct platform_device *dev)
 248 {
 249         misc_deregister(&geodewdt_miscdev);
 250         return 0;
 251 }
 252
 253 static void geodewdt_shutdown(struct platform_device *dev)
 254 {
 255         geodewdt_disable();
 256 }
 257
 258 static struct platform_driver geodewdt_driver = {
 259         .probe          = geodewdt_probe,
 260         .remove         = __devexit_p(geodewdt_remove),
 261         .shutdown       = geodewdt_shutdown,
 262         .driver         = {
 263                 .owner  = THIS_MODULE,
 264                 .name   = DRV_NAME,
 265         },
 266 };
 267
 268 static int __init geodewdt_init(void)
 269 {
 270         int ret;
 271
 272         ret = platform_driver_register(&geodewdt_driver);
 273         if (ret)
 274                 return ret;
 275
 276         geodewdt_platform_device = platform_device_register_simple(DRV_NAME,
 277                                                                 -1, NULL, 0);
 278         if (IS_ERR(geodewdt_platform_device)) {
 279                 ret = PTR_ERR(geodewdt_platform_device);
 280                 goto err;
 281         }
 282
 283         return 0;
 284 err:
 285         platform_driver_unregister(&geodewdt_driver);
 286         return ret;
 287 }
 288
 289 static void __exit geodewdt_exit(void)
 290 {
 291         platform_device_unregister(geodewdt_platform_device);
 292         platform_driver_unregister(&geodewdt_driver);
 293 }
 294
 295 module_init(geodewdt_init);
 296 module_exit(geodewdt_exit);
 297
 298 MODULE_AUTHOR("Advanced Micro Devices, Inc");
 299 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");
 300 MODULE_LICENSE("GPL");
 301 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);