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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/moduleparam.h>
  16 #include <linux/types.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/watchdog.h>
  19 #include <linux/fs.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/reboot.h>
  22 #include <linux/uaccess.h>
  23
  24 #include <linux/cs5535.h>
  25
  26 #define GEODEWDT_HZ 500
  27 #define GEODEWDT_SCALE 6
  28 #define GEODEWDT_MAX_SECONDS 131
  29
  30 #define WDT_FLAGS_OPEN 1
  31 #define WDT_FLAGS_ORPHAN 2
  32
  33 #define DRV_NAME "geodewdt"
  34 #define WATCHDOG_NAME "Geode GX/LX WDT"
  35 #define WATCHDOG_TIMEOUT 60
  36
  37 static int timeout = WATCHDOG_TIMEOUT;
  38 module_param(timeout, int, 0);
  39 MODULE_PARM_DESC(timeout,
  40         "Watchdog timeout in seconds. 1<= timeout <=131, default="
  41                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
  42
  43 static bool nowayout = WATCHDOG_NOWAYOUT;
  44 module_param(nowayout, bool, 0);
  45 MODULE_PARM_DESC(nowayout,
  46         "Watchdog cannot be stopped once started (default="
  47                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  48
  49 static struct platform_device *geodewdt_platform_device;
  50 static unsigned long wdt_flags;
  51 static struct cs5535_mfgpt_timer *wdt_timer;
  52 static int safe_close;
  53
  54 static void geodewdt_ping(void)
  55 {
  56         /* Stop the counter */
  57         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  58
  59         /* Reset the counter */
  60         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  61
  62         /* Enable the counter */
  63         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
  64 }
  65
  66 static void geodewdt_disable(void)
  67 {
  68         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  69         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  70 }
  71
  72 static int geodewdt_set_heartbeat(int val)
  73 {
  74         if (val < 1 || val > GEODEWDT_MAX_SECONDS)
  75                 return -EINVAL;
  76
  77         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  78         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ);
  79         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  80         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
  81
  82         timeout = val;
  83         return 0;
  84 }
  85
  86 static int geodewdt_open(struct inode *inode, struct file *file)
  87 {
  88         if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags))
  89                 return -EBUSY;
  90
  91         if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags))
  92                 __module_get(THIS_MODULE);
  93
  94         geodewdt_ping();
  95         return nonseekable_open(inode, file);
  96 }
  97
  98 static int geodewdt_release(struct inode *inode, struct file *file)
  99 {
 100         if (safe_close) {
 101                 geodewdt_disable();
 102                 module_put(THIS_MODULE);
 103         } else {
 104                 pr_crit("Unexpected close - watchdog is not stopping\n");
 105                 geodewdt_ping();
 106
 107                 set_bit(WDT_FLAGS_ORPHAN, &wdt_flags);
 108         }
 109
 110         clear_bit(WDT_FLAGS_OPEN, &wdt_flags);
 111         safe_close = 0;
 112         return 0;
 113 }
 114
 115 static ssize_t geodewdt_write(struct file *file, const char __user *data,
 116                                 size_t len, loff_t *ppos)
 117 {
 118         if (len) {
 119                 if (!nowayout) {
 120                         size_t i;
 121                         safe_close = 0;
 122
 123                         for (i = 0; i != len; i++) {
 124                                 char c;
 125
 126                                 if (get_user(c, data + i))
 127                                         return -EFAULT;
 128
 129                                 if (c == 'V')
 130                                         safe_close = 1;
 131                         }
 132                 }
 133
 134                 geodewdt_ping();
 135         }
 136         return len;
 137 }
 138
 139 static long geodewdt_ioctl(struct file *file, unsigned int cmd,
 140                                 unsigned long arg)
 141 {
 142         void __user *argp = (void __user *)arg;
 143         int __user *p = argp;
 144         int interval;
 145
 146         static const struct watchdog_info ident = {
 147                 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
 148                 | WDIOF_MAGICCLOSE,
 149                 .firmware_version =     1,
 150                 .identity =             WATCHDOG_NAME,
 151         };
 152
 153         switch (cmd) {
 154         case WDIOC_GETSUPPORT:
 155                 return copy_to_user(argp, &ident,
 156                                     sizeof(ident)) ? -EFAULT : 0;
 157                 break;
 158
 159         case WDIOC_GETSTATUS:
 160         case WDIOC_GETBOOTSTATUS:
 161                 return put_user(0, p);
 162
 163         case WDIOC_SETOPTIONS:
 164         {
 165                 int options, ret = -EINVAL;
 166
 167                 if (get_user(options, p))
 168                         return -EFAULT;
 169
 170                 if (options & WDIOS_DISABLECARD) {
 171                         geodewdt_disable();
 172                         ret = 0;
 173                 }
 174
 175                 if (options & WDIOS_ENABLECARD) {
 176                         geodewdt_ping();
 177                         ret = 0;
 178                 }
 179
 180                 return ret;
 181         }
 182         case WDIOC_KEEPALIVE:
 183                 geodewdt_ping();
 184                 return 0;
 185
 186         case WDIOC_SETTIMEOUT:
 187                 if (get_user(interval, p))
 188                         return -EFAULT;
 189
 190                 if (geodewdt_set_heartbeat(interval))
 191                         return -EINVAL;
 192         /* Fall through */
 193         case WDIOC_GETTIMEOUT:
 194                 return put_user(timeout, p);
 195
 196         default:
 197                 return -ENOTTY;
 198         }
 199
 200         return 0;
 201 }
 202
 203 static const struct file_operations geodewdt_fops = {
 204         .owner          = THIS_MODULE,
 205         .llseek         = no_llseek,
 206         .write          = geodewdt_write,
 207         .unlocked_ioctl = geodewdt_ioctl,
 208         .open           = geodewdt_open,
 209         .release        = geodewdt_release,
 210 };
 211
 212 static struct miscdevice geodewdt_miscdev = {
 213         .minor = WATCHDOG_MINOR,
 214         .name = "watchdog",
 215         .fops = &geodewdt_fops,
 216 };
 217
 218 static int geodewdt_probe(struct platform_device *dev)
 219 {
 220         int ret;
 221
 222         wdt_timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
 223         if (!wdt_timer) {
 224                 pr_err("No timers were available\n");
 225                 return -ENODEV;
 226         }
 227
 228         /* Set up the timer */
 229
 230         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP,
 231                           GEODEWDT_SCALE | (3 << 8));
 232
 233         /* Set up comparator 2 to reset when the event fires */
 234         cs5535_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);
 235
 236         /* Set up the initial timeout */
 237
 238         cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,
 239                 timeout * GEODEWDT_HZ);
 240
 241         ret = misc_register(&geodewdt_miscdev);
 242
 243         return ret;
 244 }
 245
 246 static int geodewdt_remove(struct platform_device *dev)
 247 {
 248         misc_deregister(&geodewdt_miscdev);
 249         return 0;
 250 }
 251
 252 static void geodewdt_shutdown(struct platform_device *dev)
 253 {
 254         geodewdt_disable();
 255 }
 256
 257 static struct platform_driver geodewdt_driver = {
 258         .probe          = geodewdt_probe,
 259         .remove         = geodewdt_remove,
 260         .shutdown       = geodewdt_shutdown,
 261         .driver         = {
 262                 .owner  = THIS_MODULE,
 263                 .name   = DRV_NAME,
 264         },
 265 };
 266
 267 static int __init geodewdt_init(void)
 268 {
 269         int ret;
 270
 271         ret = platform_driver_register(&geodewdt_driver);
 272         if (ret)
 273                 return ret;
 274
 275         geodewdt_platform_device = platform_device_register_simple(DRV_NAME,
 276                                                                 -1, NULL, 0);
 277         if (IS_ERR(geodewdt_platform_device)) {
 278                 ret = PTR_ERR(geodewdt_platform_device);
 279                 goto err;
 280         }
 281
 282         return 0;
 283 err:
 284         platform_driver_unregister(&geodewdt_driver);
 285         return ret;
 286 }
 287
 288 static void __exit geodewdt_exit(void)
 289 {
 290         platform_device_unregister(geodewdt_platform_device);
 291         platform_driver_unregister(&geodewdt_driver);
 292 }
 293
 294 module_init(geodewdt_init);
 295 module_exit(geodewdt_exit);
 296
 297 MODULE_AUTHOR("Advanced Micro Devices, Inc");
 298 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");
 299 MODULE_LICENSE("GPL");
 300 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);