drivers/watchdog/geodewdt.c

   1 /* Watchdog timer for machines with the CS5535/CS5536 companion chip
   2  *
   3  * Copyright (C) 2006-2007, Advanced Micro Devices, Inc.
   4  * Copyright (C) 2009  Andres Salomon <dilinger@collabora.co.uk>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/types.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/watchdog.h>
  18 #include <linux/fs.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/reboot.h>
  21 #include <linux/uaccess.h>
  22
  23 #include <linux/cs5535.h>
  24
  25 #define GEODEWDT_HZ 500
  26 #define GEODEWDT_SCALE 6
  27 #define GEODEWDT_MAX_SECONDS 131
  28
  29 #define WDT_FLAGS_OPEN 1
  30 #define WDT_FLAGS_ORPHAN 2
  31
  32 #define DRV_NAME "geodewdt"
  33 #define WATCHDOG_NAME "Geode GX/LX WDT"
  34 #define WATCHDOG_TIMEOUT 60
  35
  36 static int timeout = WATCHDOG_TIMEOUT;
  37 module_param(timeout, int, 0);
  38 MODULE_PARM_DESC(timeout,
  39         "Watchdog timeout in seconds. 1<= timeout <=131, default="
  40                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
  41
  42 static int nowayout = WATCHDOG_NOWAYOUT;
  43 module_param(nowayout, int, 0);
  44 MODULE_PARM_DESC(nowayout,
  45         "Watchdog cannot be stopped once started (default="
  46                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  47
  48 static struct platform_device *geodewdt_platform_device;
  49 static unsigned long wdt_flags;
  50 static struct cs5535_mfgpt_timer *wdt_timer;
  51 static int safe_close;
  52
  53 static void geodewdt_ping(void)
  54 {
  55         /* Stop the counter */
  56         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  57
  58         /* Reset the counter */
  59         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  60
  61         /* Enable the counter */
  62         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
  63 }
  64
  65 static void geodewdt_disable(void)
  66 {
  67         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  68         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  69 }
  70
  71 static int geodewdt_set_heartbeat(int val)
  72 {
  73         if (val < 1 || val > GEODEWDT_MAX_SECONDS)
  74                 return -EINVAL;
  75
  76         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  77         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ);
  78         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  79         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
  80
  81         timeout = val;
  82         return 0;
  83 }
  84
  85 static int geodewdt_open(struct inode *inode, struct file *file)
  86 {
  87         if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags))
  88                 return -EBUSY;
  89
  90         if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags))
  91                 __module_get(THIS_MODULE);
  92
  93         geodewdt_ping();
  94         return nonseekable_open(inode, file);
  95 }
  96
  97 static int geodewdt_release(struct inode *inode, struct file *file)
  98 {
  99         if (safe_close) {
 100                 geodewdt_disable();
 101                 module_put(THIS_MODULE);
 102         } else {
 103                 printk(KERN_CRIT "Unexpected close - watchdog is not stopping.\n");
 104                 geodewdt_ping();
 105
 106                 set_bit(WDT_FLAGS_ORPHAN, &wdt_flags);
 107         }
 108
 109         clear_bit(WDT_FLAGS_OPEN, &wdt_flags);
 110         safe_close = 0;
 111         return 0;
 112 }
 113
 114 static ssize_t geodewdt_write(struct file *file, const char __user *data,
 115                                 size_t len, loff_t *ppos)
 116 {
 117         if (len) {
 118                 if (!nowayout) {
 119                         size_t i;
 120                         safe_close = 0;
 121
 122                         for (i = 0; i != len; i++) {
 123                                 char c;
 124
 125                                 if (get_user(c, data + i))
 126                                         return -EFAULT;
 127
 128                                 if (c == 'V')
 129                                         safe_close = 1;
 130                         }
 131                 }
 132
 133                 geodewdt_ping();
 134         }
 135         return len;
 136 }
 137
 138 static long geodewdt_ioctl(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 const 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_SETOPTIONS:
 163         {
 164                 int options, ret = -EINVAL;
 165
 166                 if (get_user(options, p))
 167                         return -EFAULT;
 168
 169                 if (options & WDIOS_DISABLECARD) {
 170                         geodewdt_disable();
 171                         ret = 0;
 172                 }
 173
 174                 if (options & WDIOS_ENABLECARD) {
 175                         geodewdt_ping();
 176                         ret = 0;
 177                 }
 178
 179                 return ret;
 180         }
 181         case WDIOC_KEEPALIVE:
 182                 geodewdt_ping();
 183                 return 0;
 184
 185         case WDIOC_SETTIMEOUT:
 186                 if (get_user(interval, p))
 187                         return -EFAULT;
 188
 189                 if (geodewdt_set_heartbeat(interval))
 190                         return -EINVAL;
 191         /* Fall through */
 192         case WDIOC_GETTIMEOUT:
 193                 return put_user(timeout, p);
 194
 195         default:
 196                 return -ENOTTY;
 197         }
 198
 199         return 0;
 200 }
 201
 202 static const struct file_operations geodewdt_fops = {
 203         .owner          = THIS_MODULE,
 204         .llseek         = no_llseek,
 205         .write          = geodewdt_write,
 206         .unlocked_ioctl = geodewdt_ioctl,
 207         .open           = geodewdt_open,
 208         .release        = geodewdt_release,
 209 };
 210
 211 static struct miscdevice geodewdt_miscdev = {
 212         .minor = WATCHDOG_MINOR,
 213         .name = "watchdog",
 214         .fops = &geodewdt_fops,
 215 };
 216
 217 static int __devinit geodewdt_probe(struct platform_device *dev)
 218 {
 219         int ret;
 220
 221         wdt_timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
 222         if (!wdt_timer) {
 223                 printk(KERN_ERR "geodewdt:  No timers were available\n");
 224                 return -ENODEV;
 225         }
 226
 227         /* Set up the timer */
 228
 229         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP,
 230                           GEODEWDT_SCALE | (3 << 8));
 231
 232         /* Set up comparator 2 to reset when the event fires */
 233         cs5535_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);
 234
 235         /* Set up the initial timeout */
 236
 237         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,
 238                 timeout * GEODEWDT_HZ);
 239
 240         ret = misc_register(&geodewdt_miscdev);
 241
 242         return ret;
 243 }
 244
 245 static int __devexit geodewdt_remove(struct platform_device *dev)
 246 {
 247         misc_deregister(&geodewdt_miscdev);
 248         return 0;
 249 }
 250
 251 static void geodewdt_shutdown(struct platform_device *dev)
 252 {
 253         geodewdt_disable();
 254 }
 255
 256 static struct platform_driver geodewdt_driver = {
 257         .probe          = geodewdt_probe,
 258         .remove         = __devexit_p(geodewdt_remove),
 259         .shutdown       = geodewdt_shutdown,
 260         .driver         = {
 261                 .owner  = THIS_MODULE,
 262                 .name   = DRV_NAME,
 263         },
 264 };
 265
 266 static int __init geodewdt_init(void)
 267 {
 268         int ret;
 269
 270         ret = platform_driver_register(&geodewdt_driver);
 271         if (ret)
 272                 return ret;
 273
 274         geodewdt_platform_device = platform_device_register_simple(DRV_NAME,
 275                                                                 -1, NULL, 0);
 276         if (IS_ERR(geodewdt_platform_device)) {
 277                 ret = PTR_ERR(geodewdt_platform_device);
 278                 goto err;
 279         }
 280
 281         return 0;
 282 err:
 283         platform_driver_unregister(&geodewdt_driver);
 284         return ret;
 285 }
 286
 287 static void __exit geodewdt_exit(void)
 288 {
 289         platform_device_unregister(geodewdt_platform_device);
 290         platform_driver_unregister(&geodewdt_driver);
 291 }
 292
 293 module_init(geodewdt_init);
 294 module_exit(geodewdt_exit);
 295
 296 MODULE_AUTHOR("Advanced Micro Devices, Inc");
 297 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");
 298 MODULE_LICENSE("GPL");
 299 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);